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WHAT IS? It is a clinical hands-on training for experienced surgeons who have already taken the ZYGOMA 2.0 Online Training. In this exclusive one to one program you will be guided through the entire process, from planning, surgical execution on the patient and delivery of the prosthesis (immediate loading). You will have one of the greatest experts in zygomatic implants in Brazil operating on your side explaining the step-by-step of the entire process. HOW IT WORKS? Dr. Fernando Giovanella will select a patient for you to operate in Brazil under his direct guidance. We will send the CT for you to plan and discuss with Dr. Fernando Giovanella and you will come to Brazil to perform the surgery, under local or general anesthesia. WHERE? The surgeries can be performed in the city of Blumenau, Santa Catarina or surrounding cities. •Hospital Unimed Blumenau - R. Ingo Hering, 20 - Centro, Blumenau - SC, 89010-205 •Dr. Fernando Giovanella Clinic - Rua Armando Odebrecht, 70 Salas 902, Bairro Garcia, Blumenau - SC, CEP 89020-4030 google maps TRAVELING INFORMATION How to get to BLUMENAU-SC? Even though Blumenau has its own airport (private), normally passengers use scheduled flights operated from Ministro Victor Konder International Airport, located in the nearby municipality of Navegantes. If you choose not to rent a car, Gol Airlines, Azul Brazilian Airlines, Latam offer for its passengers bus transfers between Navegantes and Blumenau at regular times. Navegantes Victor Konder International Airport - 60 min (54,1 km) to Blumenau-SC - Check the transfers options at https://www.transportesexecutivo.com.br recommend hotel VILA DA VALE BOUTIQUE HOTEL - https://www.villadovalehotel.com.br WHERE TO EAT? MOINHO DO VALE - https://www.restaurantemoinhodovale.com.br FIGUEIRA - https://www.figueirarestaurante.com.br ATALIBA - http://www.ataliba.com.br SABOR IMPERIAL - https://saborimperialrestaurante.com.br WHAT'S INCLUDED Patients, Implants, Instruments and assistants Prototypes Teaching fee WHAT IS NOT INCLUDED - Airfare - Hotel Accommodations - Meals Follow me on Instagram: @drfernandogio Clínica Dr. Fernando Giovanella Rua Armando Odebrecht, 70 Salas 902, Bairro Garcia, Blumenau - SC, CEP 89020-403 Brazil +55 47 99782-2642 (only text) - https://api.whatsapp.com/send?phone=5547997822642 atendimento@fernandogiovanella.com

A perfect zygomatic implant system will bring terrible results in untrained hands. A not so good zygomatic implant system can provide excellent results if handled correctly. However, let's imagine the ideal situation. It would be the sum of a highly trained surgeon using a state-of-the-art zygomatic implant system. But what should an ideal zygomatic implant system be? It is kind of question that the beginner cannot properly answer. It is necessary to experience some situations to understand what differentiates a sound system from a system that leaves something missing. The ideal zygomatic implant system allows the surgeon to achieve his goal during the surgery, providing ideal solutions for each clinical situation, with good mechanical and biological performance. It must promote biological longevity and optimal prosthetic outcome. Several companies worldwide manufacture and sell zygomatic implants. Given so many options and possibilities, what is the best zygomatic implant system in the world? Beforehand, I can say that there is still not what we could call the "perfect" zygomatic implant system. However, some systems have certain advantages over others, which is exactly what we will cover in this post. Zygomatic implant surgery is an advanced implant dentistry technique. The surgeon must be entirely focused on the surgical technique and install the implant in the ideal position from an anatomical and prosthetic perspective. An inadequate zygomatic implant system can bring complications both immediately, in the trans-surgical period, as well as in the late postoperative period. So you have several ways to get this information. One way is to test various systems yourself and draw your conclusions until you find a system that meets your needs. Another option is to read this post to the end. Understand that what I wrote in the sequence represents my point of view, but we certainly have here how to listen to the experiences of countless other experts in zygomatic implantation around the world. Many opinions will have a commercial bias since many experts are linked to implant systems companies; however, our critical census and scientific debate will always prevail. Let us get to the point. What is the best zygomatic implant system? Complex questions require complex answers, and maybe this post will be a little long, but it will undoubtedly open your mind to what matters. To better guide our choice, we will first define the selection criteria: the ideal characteristics that a zygomatic implant system should present to best solve our clinical needs. 1) Zygomatic Implant Lengths In the case of conventional dental implants, this is not usually a big issue. However, in the case of zygomatic implants, there are essential differences between the various implant systems. In practice, when installing four zygomatic implants, the anterior implants will always be larger than the posterior implants, for anatomical reasons. It may seem like a minor detail, and it may even be in some cases, especially when it comes to hybrid Allon4, but when we are facing Allon4 Zygoma (Quad-Zygoma), the lengths of the implants can become something decisive for the resolution of some cases in an ideal way. The sizes of the zygomatic implants to be used in each case do not depend only on each patient's anatomy but also on the implants' three-dimensional positioning. The BIC (bone-to-implant contact) varies between patients, but it can also vary in the same patient, depending on the position in which the implant is installed. It is currently possible to determine the zygomatic implant's maximum anchorage area in the zygoma body with virtual planning. From there, position the implant's head in the most favorable position concerning the residual ridge and screw prosthetic emergence. Also, there is the possibility of more advanced adjustment, a fine adjustment of the three-dimensional position in the implant in the zygomatic bone. In 3D virtual planning, it is possible to plan, under an axial view, about the distance between the osteotomy/implant and the zygomatic bone's internal and external cortical. It can be a crucial factor in stabilizing zygomatic implants and preventing even a possible fracture of the zygomatic bone's outer cortical. With this degree of planning, the use of "longer than usual" implants is very common in cases of quad zygomatic implants (quad zygoma). As much as such concepts may seem to be just a personal preference, the scientific literature supports such clinical perceptions (we will see later). What about zygomatic implant companies? Are they placing implants in their production line that meet all the surgeon's clinical needs in this regard? Some companies stand out in this regard, such as SIN Implant System, which has zygomatic implants with lengths up to 62.5mm. At the other extremes, we have implant systems that are highly regarded over time, such as Nobel Biocare, but which have maximum implant lengths of 52.5mm. I have compiled the lengths of the main companies' zygomatic implants that produce and market this type of implant in the table below. Note that the minimum length of zygomatic implants varies between 30 to 35mm (variation of 5mm). On the other hand, the maximum length varies between 52.5 to 62.5mm (variation of 10mm). Why is there so much variation, especially when it comes to maximum length? What is the clinical relevance of it? It seems like a simple answer, but it is not, and to not make this post even longer, I wrote a specific post about zygomatic implant lengths. We can conclude this subtopic with the following assumption: the ideal zygomatic implant system must cover a wide range of implant lengths to have the ideal solution for each clinical situation. See more about zygomatic implant length here in this post 2) Zygomatic Implants Design & Surface For the general design of zygomatic implants, some points are critical and others desirable. For didactic purposes, we will separate by areas of the zygomatic implant. The apex of the zygomatic implants. The apex is the part of the zygomatic implant where most of the zygomatic implant insertion will take place in the bone. In some situations, there is a residual bone in the region of the maxillary ridge, but it is in the region of the zygoma body that the largest area of osseointegration will occur. As zygomatic implant surgery aims to promote immediate loading, many surgeons can immediately imagine an apex with aggressive thread design to promote optimal primary stability. Therefore, the immediate loading could be done without fear of micro-movements during the masticatory function. When installing a zygomatic implant, we must always keep in mind that the type of bone we will find during the osteotomy is a bone with a strong tendency to be corticalized. For those who have never had zygomatic implant surgery, we can make an analogy to tactile perceptions when milling an anterior region of the mandible. Most of the time, we will find a bone of excellent quality. Little corticalized bone in the mandible's anterior region can also be found, but this is the exception. If you go for mandibular protocol surgery, would you choose which dental implant design beforehand? Would you do an underpreparation and use an implant that promotes significant bone expansion? Not. The insertion torque would increase so much that it could even damage the implant connection (as for the biological part, we will address the torque issue in this other post). Keep in mind that we have a significant difference in the mandible surgery concerning the zygomatic implant. In mandible, the implant's apex is completely intraosseous (unless you bicorticalize the chin and install it beyond the mandible basal bone). Such a situation is unlikely in lower jaw surgery, but in zygomatic implants, it does happen in the zygomatic bone. During an osteotomy, we externalized the drill tip through the outer cortical of the zygomatic bone. After measurement of it, a zygomatic implant is selected. Sometimes, the implant may be installed, and the implant's apex may slightly exceed the limit of the zygoma's outer cortical. It is not a desirable and intensive maneuver, but it can happen. I had a case of a short face patient in which I selected the smallest zygomatic implant available by the company - 32.5mm - and even so, the implant's apex was slightly prominent on the outer region of the zygoma body. It's here where we need to pay attention to the detail of an ideal apex for zygomatic implant. It needs to promote a good insertion torque, but it needs to be designed for corticalized bone. It means that we need less aggressive threads. It is not uncommon for zygomatic implant surgery to have excess installation torque. If the surgeon insists on attempting to continue installing the implant with much higher than typical torques, there may be mechanical problems in the implant assembler, such as a broken screw or even fracture of the zygomatic bone. I have experienced all these situations a few times, and I can assure you that this is not a pleasant surprise. I've 'discussed these topics specifically in other posts - installation torque - fracture of the screw - fracture of the zygoma during the installation of a zygomatic implant. When we evaluate some zygomatic implants' apexes on the market, it is clear that many of them present excessively aggressive threads. Some of them have threads shape designed for soft bone, which is not suitable for the dense bone. It can make the implant installation a little difficulty in type I or II bone. See some examples below and draw your conclusions. Other zygomatic implant companies opt for an apex optimized for locking; however, the apex's end portion remains sharp. If an insertion occurs beyond the limit of the zygoma body's external cortical, this apex may be more noticeable on cutaneous palpation. See below the similarity between the NobelSpeed implant's apex concerning to the Nobel zygomatic implants' apex shape. NobelSpeed was design for osseoexpansion and underpreparation. Is it the clinical reality that we find in most cases of zygomatic implants? Finally, there are zygomatic implants whose threads are not as aggressive, and the final apex is rounded. I have been using a zygomatic implant model with a rounded apex and soft threads for more than 10 years. I can guarantee that locking these implants was never a problem. 2) Cervical Region Most companies have focused a lot of attention and study on the cervical region of conventional implants. We can say that this is possibly the most discussed millimeter in implantology worldwide. The type of connection, platform, design, and surface treatment are some variations studied to optimize osseointegration in this region as much as possible and maintain tissue stability in the long term. In this respect, it seems that the surface treatment has advantages to maintaining the peri-implant bone stability. The problem is that this same way of thinking is applied to zygomatic implants. However, many concepts applied to conventional implants cannot be directly transported to zygomatic implants, as we will see below. The first concept that we have to understand is that the zygomatic implant's main osseointegration area will occur in the body of the zygoma bone. Osseointegration in the cervical region would be desirable only when there is a residual bone in that region, which is not always the case. It is prevalent for zygomatic implants to be completely externalized (extra sinus technique), only with slight support on the maxilla's residual bone. Some zygomatic implants companies produce only one model of zygomatic implant for all clinical situations. However, others offer 3 implant design options that can be selected according to each specific situation. For didactic purposes concerning the different possibilities, we will classify the zygomatic implants in 3 modalities according to the design of the cervical region: Model I In this zygomatic implant model, there are threads and surface treatment in the apical portion, the surface is polished in the intermediate region, and in the cervical portion, the implant have surface treatment and threads. This kind of implant is indicated for situations where there is a large residual bone in the alveolar ridge region. Thus, it is possible to install the zygomatic implant so that the cervical region remains with complete bone insertion. The surface treatment and threads aim to favor osseointegration in this region. In conventional implants, the presence of this collar can decrease bone loss (1). Although this osseointegration at the level of the alveolar ridge does not have many contributions in the final stabilization of the zygomatic implant as a whole, since the main anchorage will be in the body of the zygoma, this situation is theoretically desirable due to the tissue stability that osseointegration promotes in this region. But why did I use the term "theoretically"? Because such a concept makes sense, but there are one crucial factor to consider. The precise case selection for zygomatic implant. If we look at the zygomatic implant cervical portion where the threads and surface treatment exist, ideally, a good part of this segment should be intra-bony. However, a warning signal sounds here! Probably you are likely treating a case with a zygomatic implant in which you did not need a zygomatic implant! Take a look at the case below. I haven't understood the Allon4 concept at that time yet, and I treated the patient with zygomatic implant (what I would not do today). I just needed to tilt the distal implants a little and the case could be resolved without any zygomatic implant. If there is such bone availability in this region of the ridge, it would probably be possible to tilt the conventional distal implants and solve the case with Allon4 Standard, I mean, without the need for zygomatic implants. Even in thin alveolar ridge cases in the premolar region, it is possible to use the palatal approach in distal implants. The implant head is left with the palatal turns exposed, and the implant is anchored in the canine pillar region. But, what would be the ideal indication for this zygomatic implant design? Situations where there is a thin residual bone in the premolar region, where the implant head needs a more posterior position (due to the maxillomandibular relationship), not allowing a conventional implant to be angled to the anterior one, that is, in a case where it is not it is possible to perform Allon4 Standard (unusual situation). Here there is another subtle but also clinically relevant detail. When we think about installing the implant, maintaining this residual bone crest to maintain osseointegration throughout the implant's cervical, we need to leave this implant with the head palatal displaced concerning the residual ridge. It is a reasonable position, but it is possible to let the prosthetic screw's emergence strictly at the alveolar rim level, which further improves the prosthetic outcome. If we do that, notice that the entire cervical region treated from the implant ends up being out of the bone. As a result, in addition to losing the purpose of this surface (which would be cervical osseointegration), this area is now covered only with soft tissue. The friction generated by the movement of the soft tissue (during the speech, chewing, and brushing) over the threads can lead to tissue dehiscence. If you could choose from one of the following possibilities, what would you prefer? 1) have tissue dehiscence with an implant with a threaded design and with surface treatment, or 2) have dehiscence with a zygomatic implant with a smooth and polished cervical surface. Which would accumulate less food debris and plaque? Which would promote the patient the best ability to maintain hygiene? Which would respond best to possible future soft tissue covering procedures? The answer is obvious. So this type of zygomatic implant conceptually makes sense but in practice, not so much. In virtual planning, it is possible to foresee the characteristics and nuances of each case and thus define whether this implant model will make sense or not. Regarding the range of sizes available, these implants with this configuration come in various sizes, ranging from 35mm to 60mm. It means that we have solutions for the majority of cases of Hybrid Allon4 and Zygoma. When we do Allon4 Zygoma, the anterior implants are almost always wholly externalized. Because of that, this kind of zygomatic implant cervical threads and surface treatment would not bring any advantage (neither for osseointegration nor for tissue stability). These implants commonly end up being much longer than the posterior ones. It raises a question about whether it makes sense to have this model's zygomatic implants larger than 52.5 mm with this cervical treatment. Model II This zygomatic implant model has surface treatment only in the apical portion and is indicated for severe atrophy cases where we will have fully exteriorized zygomatic implants (extra sinus technique). In these situations, we recommend installing the implants so that the implant's head is supported by the residual bone. A subtle detail to be questioned in this model is the reason for the cervical step. A small change in the cervical area, letting it slightly concave, could promote better tissue accommodation and improve the prognosis of tissue stability. I proposed this implant design in 2018, and we hope that soon some company will think about this possibility. Model III That is the design of the zygomatic implants traditionally used. They have threads in all their extension, being able to be machined or with surface treatment. Neodent/Straumann recently launched a new line of zygomatic implants where it maintained the threads and surface treatment throughout the implants but left a segment of the cervical region without threads, which may favor tissue accommodation. Nobel Biocare has a line of zygomatic implants with surface treatment but without threads. No randomized studies are comparing which of these alternatives is the best in the long run. Therefore, clinical sense and individual experiences are our only forms of decision. I have seen clinically that there is a tendency for migration of soft tissue when the implants are completely externalized, and we use implants with threads. Because of it, I decide to opt for smooth implants in such situations until we have some scientific evidence of the best alternative. 3) The Thickness of Zygomatic implants As with the lengths, there is a wide variation between the zygomatic implants' thickness between the different brands. The table below compiled the implant body dimension of the main zygomatic implant systems: Zygomatic implant fracture is rare, but there are some reports in the literature. It may be related to the lack of splinting of the implants with the metal bar, excess of the anterior cantilever, or lack of support of the implant head in the cervical region. For more than 12 years, I have been using a zygomatic implant with an apical thickness of 3.85mm and have never had this type of complication. The use of wider zygomatic implants (like NobelZygoma 0) in my vision is not justified. It can be challenging to install in some patients in quad-zygomatic implants or even could let the zygoma's outer cortical too thin, causing cracks or even complete cortical fracture. The unique zygomatic implant company that offers different alternatives for implant thickness is the SouthernImplants (3.4 e 4.1mm). 4) Zygomatic Implant Surface Treatment Before thinking about whether surface treatment is essential in zygomatic implants, we must ask ourselves what type of bone we are inserting into our implant. The zygomatic bone is different from the posterior maxilla bone (3). In the zygomatic region, there is a high tendency to corticalization due to the powerful masseter muscle's insertion. If we were to make an analogy, we could say that the zygomatic bone is a mandible-like bone. Surface treatment improves osseointegration in the case of low-quality bone (2). In the case of good-quality bone, the surface treatment does not present any additional gain, or may, according to Balshe (4), even be worse in certain situations. In addition to being a corticalized bone, there is a peculiarity of zygomatic implants, which is the possibility of tetra-corticalization; that is, the zygomatic implant passes through the zygomatic region from anterior to posterior and may have an anchorage in 4 bone cortical. In such a condition, where we have an excellent cortical bone and an implant anchored in 4 cortical, is surface treatment essential? What would be the reason? Osseointegration is not a problem in the zygoma area. Companies sometimes seem to seek solutions to problems that do not exist. But would the surface treatment have any disadvantages? Maybe. There is a frantic rush to increase BIC (bone-to-implant-contact) in implants. BIC increases have been placed as the holy grail in biomaterials research, geometry, and surface treatment. It is here that the "super-specialist" problems begin. The more graduated and the more the advancement in the academic career, the greater the tendency to have what we can call a kind of "tunnel vision." The professional delves so profoundly into specific detail of a system and forgets to see the whole. He starts to study only one specific plant and forgets to look at the forest. What do we seek with osseointegration? Anesthetic, functional and stable rehabilitation over time. It has to do with BIC, but to some extent. After spending years studying how to increase BIC by x%, it may not have the slightest clinical repercussion. In this respect, Balshe elegantly pointed out: In other words, other factors contribute to the success of osseointegration in addition to BIC, and here we may have the downside of surface treatment. In case of the need to remove the zygomatic implant for any reason, the surface treatment will promote an increase in torque for removal of the implant. From a scientific point of view, personal experience reports have little validity but can serve as a starting point for investigation. After 12 years of performing a zygomatic implant without surface treatment, according to my case series, I can say that this is the kind of surface I want to continue using unless I come across scientific evidence that proves otherwise. 5) Zygomatic Implant Assemblers It is prevalent to install zygomatic implants with a high insertion torque value. Too high torque values can damage the prosthetic connection or cause the assembler or screw to fracture. For this reason, it is crucial, during the surgical installation of the zygomatic implant, that the surgeon does not insist on proceeding with the installation if the torque is too high. Some surgeons prefer to start the installation with the handpiece and, after reaching 45N torque, the installation of the zygomatic implant is completed with the manual installation key. The installation key allows the use of high manual torque values. As it does not give us the possibility of an accurate reading of the insertion torque, this perception ends up being something subjective, and very high torques can be reached exceeding the assembler's mechanical tolerance threshold. But what would that threshold be? What can we consider a torque too high? The most of the zygomatic implant companies do not give us objective information about the zygomatic implant maximum installation torque. Evaluating the zygomatic implant main companies catalog, most of them do not provide surgeons with this information. I found this information only in the catalog of SIN Implant System and Titaniumfix. SIN Implant System guides a maximum installation torque of 80N. (Print from the SIN Implant System catalog) I have had several cases of problems with the assemblers of the zygomatic implants of SIN Implant System. Screw strength problems during installation may have occurred due to the high torques, and, perhaps, I have exceeded the maximum values. However, the problems occurred both during the installation of the implants, but there has also been a problem with the screw locking during the removal of the assembler BEFORE the installation (performing a pre-test before installing the implant in the mouth). Recently, SIN Implant System completely modified its zygomatic implant line, and we will wait to see the problem has been solved. If we think of values of 80N.cm of insertion torque in zygomatic implants, this could not be considered too high value, but something that we can control, even subjectively. However, the ideal would be for the systems to support higher values for our security (despite being unnecessary from a biological point of view). Titaniumfix recommends a maximum installation torque for the zygomatic implant of only 45N.cm. It represents an unfavorable situation in a zygomatic implant system. Having to install a zygomatic implant that cannot exceed 45N.cm would be like having a Ferrari on a race track and not exceeding the speed limit of 80km/h. It does not make any sense. What draws attention is that these implants have an internal connection and as the platform is 0o they can be installed without an assembler, which theoretically would have more resistance compared to implants with assemblers. The subject of insertion torque is something, to some extent, a little open to much discussion. On the one hand, some surgeons value and prioritize implant design optimized for maximum primary stability. On the other hand, some surgeons point out that high torques are not desirable and prefer smaller insertion torques. In that case, they plan to assign part of the responsibility to the surface treatment. However, regarding the possibility of immediate loading, the search for primary stability is a consensus among the majority. But what would be the minimum torque to load immediately safely? Is it possible to load immediately even with lower torques? In a zygomatic implant, can we apply the same way of thinking as conventional implants? Furthermore, is excess torque harmful to osseointegration? We still do not have all the answers objectively. However, we have a lot of information that needs to be compiled, digested, and disseminated so that we clinicians can put this knowledge into practice. We discussed this subject in more depth in this post. The fracture of the assembler's screw during the installation of the zygomatic implant is extremely unpleasant. It generates stress for the surgeon and can significantly increase the surgical time. When such a problem occurs, we have no other choice but to go for the solution. In this other post, we discussed the screw fracture problem and possible methods of solving this problem in more detail. 5) Zygomatic Implants Prosthetics components The case's ideal prosthetic resolution will depend mainly on the final position in which the zygomatic implant was installed. The choice of the ideal prosthetic component aims to optimize the prosthetic screw's emergence and maintain a vertical position compatible with the thickness of the soft tissues. Thus, the greater the range of possibilities for heights and angulations, the better for the surgeon or prosthetist to ideally end the case. Most zygomatic implant systems have implants with the implant head already angled to the implant body. This angle can be 45 ° (SIN, Brånemark System, NobelZygoma 45 °) or 55 ° degrees (SouthernImplants, ImplantSwiss). We have noticed in clinical practice that there is a tendency for zygomatic implants with a 45 ° head to promote good prosthetic resolution, but an increase in this angle would improve this relationship with the ridge. Therefore, perhaps implants with a 55 ° pre-angled head can be an advantageous alternative. Once the implant is installed, it is necessary to choose the prosthetic component with the ideal height. Sometimes when using the externalized technique (extra sinus), the implant head is only supported by a slight touch in the alveolar ridge. In such situations, the lower 2mm components are usually needed. The important thing is to individualize each case accordingly; therefore, several heights must be available by the implant system. Even with zygomatic implants having the head already angled 45° or 55°, the possibility of installing angled components on these implants can further optimize the ideal ratio of the emergence of the prosthetic screw. Some companies offer this alternative. More recently, some zygomatic implant systems have started to produce 0° head implants (JDentalCare, Noris, NobelZygoma 0°, IDCImplants, Titaniumfix, Neodent). An advantage would be greater flexibility of options in prosthetic resolution in addition to the connections being internal. Another advantage is that these implants can be installed without the need for assemblers, which minimizes the chance of mechanical complications during installation under high torque. Once the zygomatic implant is installed, the prosthetic emergency's anteroposterior position can be selected with the fitting of the prosthetic component. However, we have made this fine adjustment in the implants that already have a 45 ° angled head, just rotating the implant itself (with an assembler) without any significant problems. The supposed flexibility of installing 0 ° implants can only be real if there is a wide range of prosthetic component alternatives. We have to understand that we need options that give us both angles and heights alternatives. It is not always true for some systems. Let's take a look, for example, at the Neodent zygomatic implant system. 0 ° implants with internal connection. However, take a look at the prosthetic components available for these zygomatic implants. From what we have seen in our clinical situations, at least 45 ° angulation is what we need to solve our cases. Ideally, this angle could be 55 ° or even higher. The use of 30 ° and 17 ° angled mini-abutments on 0 ° zygomatic implants is rare, and, straight mini-abutments, we can say that they will never be used in zygomatic implants. So why do companies manufacture them? This type of straight abutment has its indication only for implants installed in the paranasal region, that is, they are not zygomatic implants, they are long implants (around 20 to 26mm). Thinking that we will use a minimum angulation of 45o in zygomatic implants, the system offers us only 2 prosthetic component height options, 1.5 and 2.5 mm, which could be an important limiting feature of this system. Besides, this component is fixed with a lateral through the screw and leaves a hole in the abutment side surface. Can this orifice be a plaque retentive factor if the gingival recession occurs in this region? We do not yet know the relevance of this, and long-term studies are non-existent. Some companies have a choice of components with an angle of 45 or 60 ° like NobelZygoma0 °. In addition to the 45 or 60 ° options, the Noris implant system features an intermediate 52 ° option. Some advantage of Noris Multi-Unit is the absence of lateral screw cavity. Noris seems to be a perfect solution for all clinical situations. However, when we evaluate in more detail, we see that we still don't have a perfect zygomatic implant system. Although this mini-abutment (Multi-Unit) is sold as having different transmucosal heights, it works like an extension of the implant length and not an abutment with different gengival heights. It causes the emergence of the prosthetic screw to move in the buccal-palatal direction while defining the ideal height according to the soft tissue's thickness, as in the picture below. An angled abutment with real height variation would be like that from Nobel Biocare. In this way, it is possible to select the ideal height without interfering with the prosthetic screw emergence's buccal-palatal position. So that way, we have the ideal solution? NO! A potential problem to be investigated in this type of abutment is that the fixation screw's orifice remains in the palatal region. The palatine mucosa is resistant to tissue dehiscence, so much so that it is routine to install implants with a palatal approach, leaving some exposed threads. However, we still do not know whether this orifice in this kind of mini-abutment will cause plaque accumulation or potential complications in tissue stability, mostly when located more superficially about the gingival margin. TitaniumFix components, in addition to only 17 and 30-degree angles, have only two heights available of 2 and 3mm. But the worst aspect of this system is that the screw is inserted into the abutment side. Any small tissue dehiscence may expose this hole to the oral environment. If using zygomatic implants with an angle of 45o, we have an optimal position concerning prosthetic emergence; the possibility of using angled components is an advantage of the Nobel and DSP systems. 6) Scientific publications Regarding scientific publications and time on the market, no zygomatic implant system can match Nobel Biocare. Among the zygomatic implant models currently available, undoubtedly the zygomatic implants with head 45o and external hexagonal connection are the types of zygomatic implants most researched. All-new forms of 0o prosthetic connection are still being validated by the clinical studies to come. It is worth evaluating whether you will want to participate in these "tests" of these new systems or use something already established in the literature in your private clinic. When it comes to dentistry, I never want to be the first to use something recently launched on my patients or be the last who is still using a specific product. 7) Zygomatic Implant Surgical kit It is interesting to note that some zygomatic implant systems still insist on the initial drill in the spherical shape, which is terrible for the initial drilling. In addition to promoting more significant oscillation, this type of drill has great difficulty and instability for cutting oblique surfaces. Significant advances have taken place in recent years, and most companies have evolved in this regard and have started to offer a lance format for initial drilling. However, the pioneer Nobel Biocare, SIN Implant System and Dental Care, still provide spherical drills for initial drilling in their zygomatic implant systems. Some companies like SouthernImplants and TitaniumFix commercialize both initial spherical drills and spear. Regarding the subsequent drill sequence, there is significant variation about the thickness of the drills (due to the variation in the implants' thickness between the different zygomatic implant systems), and the most of systems only provide a single length of drills. It is necessary to use lip protector in some clinical situations when osteotomy is performed on patients with reduced facial dimensions. On the other hand, zygomatic implant systems such as Implance, Nobel Biocare (NobelZygoma), ShoutherImplants, JDentalCare and ImplantSwiss offer 2 options for drill sizes, which facilitate milling in specific clinical situations. On the other hand, Noris offers the most complete system of zygomatic implant drills, offering drills of various sizes for the most different clinical situations. See below the main designs of the drills of the different zygomatic implant systems. Conclusion There is no ideal zygomatic implant system. Mastering the concepts discussed above will make you understand the advantages and limitations of each system. The dental implant company that attends to these concepts can create a unique zygomatic implant system on the market and will undoubtedly promote great help so that the surgeon can solve the most diverse clinical situations in the best possible way. In the meantime, we need to adapt to the limitations of the zygomatic implant systems available on the market. What zygomatic implant systems have you been using? What have been your challenges? Share your experiences below, and we will together evolve our technique and pressure companies to evolve for us and with us. REFERENCES (1) Koodaryan R, Hafezeqoran A. Evaluation of Implant Collar Surfaces for Marginal Bone Loss: A Systematic Review and Meta-Analysis. Biomed Res Int. 2016;2016:4987526. doi:10.1155/2016/4987526 - https://pubmed.ncbi.nlm.nih.gov/27493957/ (2) Goiato MC, dos Santos DM, Santiago JF Jr, Moreno A, Pellizzer EP. Longevity of dental implants in type IV bone: a systematic review. Int J Oral Maxillofac Surg. 2014;43(9):1108-1116. doi:10.1016/j.ijom.2014.02.016 - https://pubmed.ncbi.nlm.nih.gov/24679842/ (3) Bertl, K. et al. MicroCT-based evaluation of the trabecular bone quality of different implant anchorage sites for masticatory rehabilitation of the maxilla. J Craniomaxillofac Surg 43, 961-968, doi:10.1016/j.jcms.2015.04.008 (2015). https://pubmed.ncbi.nlm.nih.gov/26027862/ (4) Balshe AA, Assad DA, Eckert SE, Koka S, Weaver AL. A retrospective study of the survival of smooth- and rough-surface dental implants. Int J Oral Maxillofac Implants. 2009;24(6):1113-1118. https://pubmed.ncbi.nlm.nih.gov/20162117/

Yes, it is. That's why the zygomatic implant doesn't work! Many professionals still believe that zygomatic implants are outdated and do not bring good clinical results. But is this a problem with the zygomatic implant technique, the misuse of the method, or the product of bad science? There is only one thing more dangerous than the professional who does not study. That is the professional who blindly believes in everything he read, and in this post, you will practically understand this through 2 weird examples when it comes to zygomatic implants. Understand: There are two extremes. At one extreme, we have dentistry that does not follow evidence-based conduct, which is a problem. At the other extreme, we have the repeaters of ideas, those who only recite excerpts from books and articles literally and confuse information with knowledge. And we have a third area, which is the optimum area, where reality, practical experimentation, and clinical results reside. It is here that there is the so-called critical thinking and systemic thinking. You base your conduct on evidence, but at the same time, you triangulate them with practical insights and assess situations from various perspectives. You can contextualize what you are reading and not passively accept everything. The zygomatic implant has been the dentistry area most affected by this simplistic approach and later claims that the zygomatic implant does not work. Let's see this in practice. Take a look at this article published in the Journal of Prosthodontics (1). The authors propose a way to optimize the trajectory of the zygomatic implant. But take a look at this zygomatic implant on the right side. The zygomatic implant is already violating the orbital cavity in virtual planning! We all know that it can have a tremendous apical deviation in the trajectory of a long implant (as a zygomatic implant). You add a potentially significant apical variation with such bad planning, which can result in a catastrophic error! Do you understand now why they say that zygomatic implants don't work? If that's what they publish, imagine the rest. Is that why the zygomatic implant doesn't work? But let's go ahead, an article published in the renowned International Journal of Oral & Maxillofacial Implants (2). They wanted to evaluate the influence of alveolar defects in the distribution of stress when using 4 zygomatic implants (Quad Zygoma). Now let's assess how these implants were installed. We can see that all zygomatic implants were installed in an excessively posterior position in the alveolar ridge region. The prosthetic screw emergence of the posterior zygomatic implants would come out there in the third molar region, or even far beyond. Another problem: the distal implants were installed crossing the infratemporal fossa, taking only a small portion of the most terminal part of the zygomatic bone, close to the zygomatic arch, where the bone is much thinner and has a bad bone anchorage. In such conditions, the implants may even be unstable and have movement on pressure, then I ask: Is that why the zygomatic implant doesn't work? This unfavorable, more posterior position makes shorter zygomatic implants necessary. Do you understand now why companies make zygomatic implants that are shorter than ideal? They don't know about these technical details. This issue is critical, and I talk more about zygomatic implant lengths in this post and zygomatic implant systems in this post here. Take a look at the disposition of the implants' emergence concerning the prosthesis and look at the anterior cantilever's size. This is bizarre and clinically unviable. Then a zygomatic implant fracture occurs, and companies think the solution is to create thicker zygomatic implants. It's a mistake, Nobel Biocare! It's not a problem with the thickness of zygomatic implants. It is a problem with the length of the implants. When the head of the zygomatic implants is more anterior in the ridge, the anterior cantilever is much smaller. However, to do this, we need zygomatic implants larger than 52.5mm. (I talk more about that in my book ZYGOMA 2.0 - The New Age of Zygomatic Implants [sold out]) and also in this post. But anyway, the zygomatic implant is an incredible technique; it removes the patient from the bone graft and allows immediate loading with a high success rate in the short and long term (around 95% success after 12 years(3)). However, if you really want to learn zygomatic implants, start studying and be critical of what you see in Facebook groups and even in scientific articles. It is not because something is published that it is an absolute truth. Another issue is that scientific articles that published long-term follow-up often used techniques for installing zygomatic implants that we no longer use today (such as the Brånemark Technique). In the future, new publications will most likely show an even more significant increase in success rates and a massive decrease in the rate of complications. Only by having the courage to apply a critical way of evaluating studies will we perform and teach zygomatic implants responsibly and with a commitment to our clinical outcome and our patients. This post is not a personal criticism of any company or author but a way to stimulate the advancement of science, critical thinking, and, consequently, the truth. Share your thoughts below! References (1) Wang CI, Cho SH, Cho D, Ducote C, Reddy LV, Sinada N. A 3D-Printed Guide to Assist in Sinus Slot Preparation for the Optimization of Zygomatic Implant Axis Trajectory. J Prosthodont. 2020 Feb; 29 (2): 179-184. doi: 10.1111 / jopr.13139. Epub 2020 Jan 11. PMID 31889369. https://onlinelibrary.wiley.com/doi/abs/10.1111/jopr.13139 (2) Duan Y, Chandran R, Cherry D. Influence of Alveolar Bone Defects on the Stress Distribution in Quad Zygomatic Implant-Supported Maxillary Prosthesis. Int J Oral Maxillofac Implants 7 , 203-211 (1992). 2018 May / Jun; 33 (3): 693-700. doi: 10.11607 / jomi.4692. PMID 29763505. http://quintpub.com/journals/omi/abstract.php?iss2_id=1533&article_id=18448#.X8ThKi2cZGM (3) Chrcanovic BR, Albrektsson T, Wennerberg A. Survival and Complications of Zygomatic Implants: An Updated Systematic Review. J Oral Maxillofac Surg. 2016 Oct; 74 (10): 1949-64. doi: 10.1016 / j.joms.2016.06.166. Epub 2016 Jun 18. PMID 27422530. https://pubmed.ncbi.nlm.nih.gov/24679842/

Principles of Cortically Fixed At Once (CF@O) Dr.Henri Diederich, doctor in dental medecine Luxembourg 1. Introduction Whenever the use of implants is being considered or has been decided upon, the perennial issue of possible bone insufficiency will have to be addressed. Any type of bone insufficiency - quantitative or qualitative, localized or more general - is a major obstacle to the use of implants, and so to prosthetic restoration. Practitioners use various methods to resolve this problem, either by increasing bone volume (bone grafts, sinus lift, etc.) or adapting to the patient’s bone volume by changing the size or shape of implants, implant sites and operative protocols. We will describe the Principles of the Cortically Fixed at Once, which is a useful alternative to conventional implant placement in cases where there is substantial bone resorption (atrophic maxillae, resorption caused by trauma, substantial pneumatisation of the sinuses, etc.) However, it is important to emphasize that this technique needs special training, complete mastery of the surgery involved and a very good knowledge of craniofacial anatomy. It is therefore intended for use by an experienced implantologist, or even a very highly experienced implant specialist, rather than a beginner. 2. Background There were a number of different stages in the journey towards cortical implant placement and the foundations of CF@O; amongst other names, the discipline was called basal implantology in France, and indeed that name is still used today. The term basal implantology was first used in 1972 by Jean-Marc Juliet. He described the advantages of using two cortical anchorages and developed an implant (T3D) consisting of a perforated rectangular titanium plate with a vertical pillar soldered onto it (Fig. 2.1). In 1975, another French practitioner, Dr Clunet-Coste applied for a patent for an implant that was similar, but with a more rounded plate design with larger holes. He also proposed a system in which the pillar was screwed onto the implant (1). Fig. 2.1 Implant designed by Dr Jean-Marc Juliet Fig. 2.2 Lateral insertion of the implant designed by Dr G.Scortecci Fig. 2.3 Self-tapping disc implant. However, basal implantology really began to develop with Dr.Gerard Scortecci; in the early 1980s he proposed the Diskimplant®, disc implant system that was inserted laterally (Fig. 2.2), and which he refined over the next few years. In 1985, self-tapping disk- implants (Fig. 2.3) were a very attractive idea, but they were not widely used because the pillar diameter had to be the same as the diameter of the drill bit on the handpiece, or 1.6 mm, which often led to implant fractures at this point. The shape, size and holes of disc implants were modified many times by their inventor to improve implant osseointegration and to offer a more satisfactory response to the constraints of the prosthesis. In 1982, a Belgian dentist called Robert Streel patented an implant which was similar, but with variable geometry (it was pliable) to improve primary stability. A number of basal implants were developed during the 1980s, some of which (such as the implant designed by A. Kurtis) made use of innovative geometric properties to divert or redistribute the various forces, and to give the implant a certain elasticity, while others (such as Kawahara’s implant designed in 1989) had irregular perforations over the surface to improve the blood supply around the implant. The 1990s and 2000s brought many improvements and variants, too numerous to describe here; however, as an example we would mention two- or three-plate disk- implants (Scortecci), asymmetrical disc- implants (Spahn, Ihde) and disc- implants using osteosynthesis plates (Fig. 2.6) (1). Fig. 2.6 Disc-implants by Dr. Stefan Ihde Two plate disc-implants (Spahn) Plate implant with osteosyntheis screw (Scortecci) 3. Anatomical and physiological considerations 3.1 Characteristics and dynamics of bone tissue in the various areas used for implants 3.1.1 Dynamics of facial bone tissues As far back as 1771, Hunter stated that the alveolar processes were part of the teeth rather than the maxilla; they were born with the teeth, accompanied them when they erupted and when they moved within the arch throughout the individual’s life, and they disappeared when they did. Over time, and as teeth are lost, the alveolar bone is remodelled, gradually reducing in volume and density. As shown by Lindhe’s studies, resorption of alveolar bone is a normal consequence of tooth loss, taking place centripetally in the maxilla and centrifugally in the mandible. These bone losses affect an average 40–60% of the original height and thickness, with maximum loss during the first year (2). The speed of this bone softening also varies according to a number of parameters such as age, quality of healing, degree of edentulousness and the presence of bone stimulation (non-iatrogenic effects) or conversely, with the application of excessive forces that accelerate osteolysis. Subsequently, implantologists have to use different ways of reconstituting the bone (onlay grafts, Summers’ osteotome technique, sinus lift, etc.) to restore good conditions for axial implant placement. However, these methods still require sufficient residual bone. Fig. 3.1 Bone resorption cycle in the maxilla and the mandible (3) The facial pillars consist of this basal or cortical bone; they are areas of thickened bone and multiple muscle insertions that are the first choice sites for cortical implant placement: The various regions are (Fig. 3.2): In the maxilla: The pterygoid pillars The zygomatic pillars The canine pillars and the nasal spine In the mandible: The retromolar areas The area of the mandibular symphysis Fig. 3.2 The pterygoid, zygomatic and canine pillars identified by implants on a CT scan (3) 3.1.2 Physiological characteristics of basal bone 3.1.2.1 General summary Basal bone is compact bone, i.e. Haversian bone, consisting of osteons surrounding the Haversian canals. Osteoblasts are located on the periphery of the osteon, producing bone by gradually becoming enclosed in a bone matrix; they then become osteocytes, which communicate between themselves via canaliculi. They form concentric layers around the central canal. They live for ten years and regulate the activity of osteoblasts and osteoclasts (Fig. 3.3). Fig. 3.3 Haversian bone (2) Bone density is measured using the Lekholm and Zarb classification (Fig. 3.4) (2). Fig. 3.4 Lekholm and Zarb classification of bone quality (1985) Type I: Consists almost entirely of homogeneous compact bone Type II: A thick layer of compact bone surrounds a core of dense trabecular bone Type III: A thin layer of cortical bone surrounds a core of dense trabecular bone Type IV: A thin layer of cortical bone surrounds a core of low density trabecular bone 3.1.2.2 Characteristics of basal bone Basal bone may be one of two types of bone, i.e. very dense type I bone that can fracture easily, or conversely, low-density type IV bone with yellow bone marrow filled with fat cells. Cortical basal bone has a very high mineral content (99% hydroxyapatite and type I collagen), they have few cells and a sparse vascular network (vascular supply is mainly via the periosteum). Although basal bone generally has good mechanical properties, it is very thin (1–8 mm high and 1–5 mm wide), and its reduced blood supply means there is a higher risk of infection (osteitis) and slower healing. So basal implantology procedures must be carried out in rigorously aseptic conditions, identical to those used in orthopaedic surgery, and the periosteum must remain intact. 3.1.2.3 Anatomical sites where the CF@O protocol is applied 3.1.3 Pterygoid-maxillary region The pterygoid region is a very useful site. It offers sufficient bone volume for solid posterior anchorage, while avoiding the need for cantilevers in prosthetic structures. The area is defined anteriorly by the posterior wall of the maxillary sinus, by the posterior or pterygopalatine surface of the maxilla in contact with the pterygoid process of the sphenoid bone and the pyramidal process of the palatine bone posteriorly, and the perpendicular plate of the palatine bone medially (4). The maxillary tuberosity consists of areas of thin cortical bone onto which the anterior fibres of the medial and lateral pterygoid muscles insert, on its lateral surface. The presence of these powerful muscle insertions often makes it bulky. The maxillary bone has a flat suture with the pterygoid process of the sphenoid bone and the pyramidal process of the palatine bone; this suture forms a very resistant buttress. A knowledge and understanding of this architecture are needed for safe insertion of implants. The anatomical hazards of this region may involve bleeding because of (4, 5): The descending palatine artery, whose path goes through its canal on the posterior border of the maxilla. It travels downwards and enters the palatine canal (or posterior palate) with the greater and lesser palatine nerves (the sensory branch originating in the pterygopalatine ganglion of V2; it innervates the gums, the mucosa and the glands of most of the hard palate). It then divides into the greater and lesser palatine arteries, which irrigate the mucosa and the glands of the palate. The position of the canal must be correctly identified as it governs the incision, dissection and, of course, the axis of the implant (Fig. 3.6). The internal maxillary artery is situated externally and very high in the pterygoid (it extends from the neck of the condyle to the top of the zygomatic or infratemporal fossa). Fig. 3.6 Maxillary and palatine artery. left Nasal septum (raised) Diagrammatic hinge Anterior septal branch Anterior lateral nasal branch Lateral nasal branch of anterior ethmoidal artery Alar branches of the lateral nasal artery (lateral nasal branch of the facial artery) Anastomosis between the posterior septal branch of the sphenopalatine artery and the greater palatine artery in the incisive canal Greater palatine artery Lateral wall of the nasal cavity right Branch of the nasal septum of the superior labial artery (superior labial branch of the facial artery) Anastomosis between the septal branch of the sphenopalatine artery and the greater palatine artery in the incisive canal Septal and lateral nasal branches of the posterior ethmoidal artery Posterior septal branch of the sphenopalatine artery Sphenopalatine artery Sphenopalatine foramen Posterior lateral branches of the maxillary artery Maxillary artery External carotid artery Lesser palatine foramen and lesser palatine artery Greater palatine foramen and greater palatine artery Bone quality in the area of the tuberosity is usually poor (Lekholm and Zarb classification Type IV), unlike that of the pterygoid-palatine buttress (dense type I bone). Bone density can be measured radiologically. It is possible to analyze this complex region preoperatively using modern imaging methods (cone beam or CT scan) and by constructing a stereolithographic model (three-dimensional reconstruction of the bone Fig. 3.7). Fig. 3.7 Stereolithographic model produced from a scan 3.1.4 2 Zygomatic process of the zygomatic bone The body of the zygomatic bone (also called the malar bone or the zygoma) corresponds to the palpable raised area of the cheekbone (Fig. 3.8). This body is connected to the other facial bones by four extensions known as processes (4): A medial extension towards the lower orbital margin A superior extension towards the lateral orbital margin, joining the frontal bone An inferior extension towards the maxillary bone; this process can be felt in the mouth Right zygomatic bone A posterior extension connecting it with the narrow extension of the temporal bone Fig. 3.8 Zygomatic bone left articulates with the frontal bone Frontal process Zygomaticofacial foramen articulates with the temporal bone Greater zygomatic muscle Lesser zygomatic muscl right articulates with the sphenoid Orbital margin Orbital surface Zygomatico-orbital foramen Levator muscle of upper lip articulates with the sphenoid Right zygomatic bone The zygomatic bone could be likened to a pyramid, providing a solid anatomical structure for implant anchorage. Histological analysis of this region has shown that the bone is homogeneous and dense, with very high bone density (up to 98%) (8). According to an anatomical study, the mean length of available bone in this region is 14 mm. 3.1.5 Canine pillar This is a pyramid-shaped space with three walls, with: a superficial anterolateral surface an anteromedial surface corresponding to the medial wall of the nasal cavities a posteromedial surface corresponding to the extension of the sinus a base which is the canine/premolar segment a summit which merges into the rising process of the maxilla. This pyramid goes upwards, inwards, and slightly forwards. The canine pillar is part of the functional anatomy of the skull, located in front of the maxillary sinus, in the lateral part of the maxillary bone. It is a bony framework by which forces applied to the teeth are transmitted to the facial skeleton (Fig. 3.9) (3, 4) Fig. 3.9 Vertical pillars of the face After teeth are lost, the residual bone volume retains the biomechanical property that makes it a valuable anchorage in basal implantology. However, in an individual with total or subtotal edentulousness, the bone volume is not always related to the biomechanical properties of the canine pillar. That pillar is located at the border of two air cavities, the maxillary sinus posteriorly and the nasal cavity anteriorly and medially. If there has been major bone resorption, the pillar is reduced to being a simple septum consisting of three contiguous plates, the medial wall of the maxillary sinus, the septum sinuum sphenoidalis and the lateral surface of the maxillary bone at the posterior border of the piriform aperture. In the event of major bone resorption, anchorage will have to be found at the junction of these three bony walls. The force lines of the canine pillar correspond to the position of the tooth in its socket. The root is located very superficially, and the labial cortical bone forming the canine eminence is very thin. This cortical bone is often damaged when a tooth is lost, increasing the effect of centripetal resorption of the alveolar crest, with the result that the implant is positioned more medially in relation to the site of the natural tooth; however, to ensure good occlusal relationships and good mechanical behaviour of the implant-plus-prosthesis assembly, it is better for canine implants to be placed as close as possible to tooth roots. This basic concept of implant biomechanics ensures that osseointegration will be maintained after loading. Canine pillar bone is generally type II bone; a CT scan is needed to establish bone volume and identify the various bone septa bordering it. The main anatomical hazards in this region are (4): The anterior and superior dental canal About five millimetres behind the emergence of the infraorbital foramen, a narrow canaliculus takes off from the floor of the canal and travels downwards, crossing the canine pillar. It provides a passage for the dental blood vessels and nerves serving the canine and the incisors on the same side. Damage to these arterioles during drilling may lead to non-negligible bleeding. Implant insertion will stem the bleeding immediately. The arteries are visible on axial CT sections above the floor of the nasal cavities. There is no reason to look for them routinely. No special precautions are needed during the procedure, as any trauma caused to them is minor. At the least, in the event of substantial bleeding, the procedure should be speeded up and the direction indicators should be replaced in the drill socket between bursts of drilling, to reduce bleeding. The infraorbital foramen This is located on the anterior surface of the upper maxilla; it terminates in front of the infraorbital canal. It is generally located five to six millimetres underneath the orbital margin, about three centimetres from the midline. A lesion of the infraorbital nerves and blood vessels causes anaesthesia or paraesthesia of the upper lip and the incisors/canines on the same side. In normal clinical situations, there is no risk of this structure being damaged. The nasal cavities At this level, the medial wall of the nasal cavity is the anterior medial surface of the canine pillar. There is a considerable risk of penetrating the nose during drilling, and then during implant placement. A lesion of the highly vascularized nasal mucosa may cause epistaxis (bleeding to the exterior via the nostrils, and sometimes flowing into the pharynx) and a potential risk of infection in the apical part of the implant. 3.1.6 Nasal spine The anterior nasal spine of the maxilla is a small protuberance at the base of the nasal cavity, just above the teeth. The spine juts out slightly from the maxilla in the vertical plane and acts as an anchorage point for nasal cartilage. By extrapolation, in cortical implantology the nasal spine region extends from the floor of the nasal cavity upwards, from the two canine eminences laterally, the palatal arch of the maxilla posteriorly and the lateral part of the premaxilla anteriorly. In this region, the lateral part of the premaxilla may take one of two very different forms. It may either be a flat table, gradually thickening from the crest to the base of the nostrils. This situation, unfortunately the less common of the two, is very favourable for implant placement, as the implant is protected by an area of bone that gradually gets thicker. Alternatively, the lateral part of the premaxilla may be more or less concave, requiring accurate knowledge of bone volume to avoid going through the lateral part of the bone. In fact, the main anatomical problem in the region of the incisors is not the height of the bone, which is often quite substantial, but its thickness (2, 4). Anatomical risks of the region: Anterior palatine canal Situated behind the central incisors, its path is almost perpendicular. It divides into two canals as it reaches the bony part of the palate. The palatine canal is crossed by the nasopalatine nerves and vessels. An unavoidable consequence of damage to the anterior palatine canal is the risk of the implant not becoming osseointegrated. There is a risk of bleeding, but this is easily controlled. It may lead to transient loss of feeling in the incisive papilla. Its diameter varies; it can only be seen on axial CT sections. Nasal cavities At this level, only the floor of a nasal cavity is likely to be damaged during implant placement. The anterior part of the nasal cavity is made up of the palatine process of the upper maxilla. It is covered with periosteum and a thick mucosa with a good blood supply. In order to reinforce primary stability it is sometimes necessary to cross the floor of the nasal cavity; if the drill slips, it may perforate the nasal mucosa and cause epistaxis (as described earlier for the canine pillar). The distance between the crest and the floor of the nasal cavity can be established by sagittal CT sections. Regions of the retromolar triangle Anterior part of the mandible 4. CF@O Principles and Protocol The Cortically Fixed at Once (CF@O) approach is based on concepts that differ radically from those of axial implant placement (Brånemark). The idea of using bone width rather than height was put forward by Jean-Marc Juliet in 1972 with his T3D implant with tricortical anchorage. This founding concept of the discipline involved looking for cortical anchorages in basal bone, which is histologically and physiologically different from crestal bone. The principles that have been used by orthopaedic specialists for decades can be transposed to the principles of CF@O, i.e. that the structure of the bone means that it can safely take a titanium implant and heal even after immediate loading and under the effect of measured stresses without shear forces (1, 3, 9). The current principles are: Anatomical and physiological concepts: Anchorage in the facial pillars Surgery guided by the anatomy (use of existing bone) Implant adapted to the existing bone (leading to the need to have a range of implants of different shapes and sizes, or even implants that can be adjusted as with hybrid plates Preservation of the maxillary sinus No major surgery Biomechanical and prosthetic concepts: Primary stability is crucial Immediate loading (major advantage made possible by multiple cortical anchorage in dense bones) A very rigid and screw-retained external fixator that encourages bone healing (L-shaped titanium or cobalt-chromium frame) 4.1. Preparation and surgical protocol Implant placement remains primarily a treatment for tooth loss. The cosmetic aspect is important, but above all it has to stay within the bounds of what is possible and reasonable. Examination of documents and articulator models Biochemical tests Analysis of radiology and CT images Hard copy: transparent implant placement manual Computer support (navigation, simulation) Resin modelling: stereolithographic models Aesthetic and functional analysis of the assembly All these factors are involved in decisions about the final prosthesis and the number and type of implants. Actual procedure The patient will have been told not to arrive in a fasted state if they are to have local anaesthesia 100 mg of Atarax® ((hydroxyzine) given orally one hour before they are taken to the chair in the operating room. However, if the patient develops an infectious disease shortly before the procedure (sinusitis with discharge, sore throat, bronchitis, fever, etc.), the procedure should be postponed. Typical sequences of operative stages Give regional and local anaesthesia. Make a full-thickness crestal incision (open-flap) Dissect the covering mucosa and periosteum and make a full-thickness labial and lingual (or palatal) flap. Cover the plates in the maxilla with a buccal fat pad or biomaterial Cover the plates in the mandible with biomaterial, PRF or MPM Close the mucosal and periosteal flap with interrupted sutures. Take an impression for immediate loading 4.2 Placement of single-piece axial implants The axial implants used have certain characteristics: (Fig. 5.1) Nature and texture These implants are machined in grade 5 titanium with an HA/BTCP surface (hydroxyapatite/beta tricalcium phosphate) Implants: Shape and size The implants may be conical or may have a cylindrical thread and conical core; they may be single-piece implants or have a separate abutment; dimensions are generally 3–5.5 mm for diameter and 8–22 mm for length. Some axial implants are double-threaded, with a wide thread in the lower section and a narrower thread in the upper section, which gives them the advantage of being simultaneously self-tapping and compressive. So the shape of these implants already provides mechanical retention after they have been placed. Other specific axial implants used in conjunction with bone probing allow bone crests to be expanded (6, 11). Mechanical properties These implants resist lateral movement well. Insertion The axial implants used are generally intended for the anterior part of the mandible or the maxilla (apart from pterygoid implants, which are also axial implants but will be treated separately) where there is sufficient bone height. They allow bicortical or even tricortical anchorage and provide very good stability, even in medium-dense bone. The practitioner should choose an implant appropriate for the bone density at the site (compressive, self-tapping) sometimes perioperatively, hence the benefit of having a wide range of axial implants available. Insertion of these implants is similar to that of crestal implants, but it must result in primary stability, for which a minimum torque of 35 Ncm is recommended. Drilling is done from the top of the crest with a low-speed contra angle handpiece. The implant is screwed into a crest > 7 mm high and > 6 mm wide. The axis of the prosthesis follows that of the crest (9). 4.3 Tuberosity and Pterygoid implants Pterygoid implants were first proposed by Linkow in 1975. A pterygoid implant is defined as an axial implant placed through the maxillary tuberosity with fixation apically in the pterygoid process of the sphenoid bone and in the pyramidal process of the palatine bone. The method was taken up and described by JF Tulasne in 1992. The properties of tuberosity and pterygoid implants are adapted for the region: They are relatively long so that they can cross the mucosa (which is often thick in this region) and the tuberosity, and then lodge the implant apex in the cortical bone of the pterygopalatine suture. According to a (cone-beam) radiology study carried out in a cohort of 100 patients (Rodriguez and co-authors, 2014), the mean length of implant site (from the tuberosity to the most apical part of the pterygoid process) is 22.5 ± 4.8 mm. This suggests that 16 and 20 mm implants would be adequate for most measurements and would allow cortical anchorage while retaining a comfortable safety margin (4–7). They have a pointed, self-tapping apex to ensure strong anchorage when inserted, which is done manually with under-drilling (both diameter and depth). They have a wide thread profile at the neck to provide compression in the region of the tuberosity, where the bone is often of low density. Tuberosity and pterygoid implants may be single-piece (easier to handle in this region) or conventional implants. Their use requires careful preoperative studies (stereolithography, 3D modelling software, identification of anatomical hazards, working length, trajectory), together with experience acquired in a team setting and a high skill level. A full-thickness crestal incision is made on an edentulous crest as far as the back of the tuberosity, and extended by a vestibular releasing incision. The drill entry point is often marked 5–6 mm in front of the posterior region of the tuberosity. The drill axis runs towards the palate about 20–30° in the horizontal plane and about 45° from the maxillary plane. Drilling with a pilot drill only continues up to the pterygopalatine-tuberosity suture, which is the anchorage region for a pterygoid implant. Three different types of drills are used for insertion. All preparation is done in an underprepared mode, at a working speed of 600 rpm or manually. The implant is then inserted manually using a bone condensation technique, as it is self-tapping and compressive (Figs. 5.4 and 5.5). Many studies carried out with this type of implant have demonstrated a very good success rate - 96.45% (Monteiro and co-authors) and 98.6% for Rodriguez and co-authors (for 454 implants), with a recommended implant diameter of 3.75 mm for 18 mm length. Depending on the actual anatomy, 3.3–4.1 mm diameter, 16–21 mm long implants may be used. Fig. 5.4 Insertion axis of pterygoid implant Fig. 5.5 Pterygoid implant and implant holder Fig. 5.6 Pre-implantation study using SIMPLANT® software (15) New Pterygoid implants were designed under the guidance of Henri Diederich, Luxembourg with the collaboration of the Swiss company TRATE. These implants have a surface treatment HA/TCP and have a conical shape with compressive threads. 4.4 Hybrid plates The first Hybrid Plates were introduced by G. Scortecci in July 2000; they had a large base plate (25, 33 or 43 mm long, 7, 9 or 12 mm wide) (Fig. 5.7). The first procedure using these plates was carried out in 2000 in a patient with a fractured atrophic mandible. Insertion of these Diskimplants®name given by Scortecci with a plate into the posterior parts of the triangles made it possible to reduce the mandibular fracture, heal it and retain almost all of the implants. Since September 2002, they have all been fitted with osteosynthesis screws; their design is based on both asymmetrical disc- implants and the screwed-in osteosynthesis plates used in traumatology and maxillofacial surgery. Since then, the spectrum of indications for this type of implant has grown much broader than was originally intended, extending to the canine region, the region of the first molars and the zygomatic region in the maxilla, and the retromolar triangle with cortical anchorage in the ascending ramus in the mandible (3, 11) (12) These implants were developed further and modified by Dr Ansel-France and Dr Diederich and PHOENIX®, Germany (Fig. 5.7). Plate implants are manufactured in grade 2 pure titanium (345 N/mm2 less mechanical resistance than grade 4 titanium at 550 N/mm2, but better malleability) (11). Their thin profile (0.6 mm section for Phoenix® plate implants) and the specific features of their manufacture make them very flexible and allow the plates to be fitted to any shape of bone. The implants are designed to be endosseous or subperiosteal, fixed mainly by osteosynthesis screws depending on the conditions and regions concerned. They offer a screwed-in connection platform in with an external hexagonal screw (Scortecci) or morse taper (Ansel/Diederich). Fig. 5.7 Plate implants designed by Scortecci (left) and Ansel/Diederich (right) A new plate design is performed by Henri Diederich with the collaboration of TRATE (Switzerland) HENGG1 (Huge Efficiency No Graft Gear) (2016) Hengg-1, Hengg-3 and Hengg-2 (left to right) Insertion of hybrid plates implants according to the implant zone Canine plate implant Insertion of a hybride-plate (in general) starts with a midline crestal incision and dissection of a mucosal and periosteal flap for maximum visibility of the region concerned. In the case of the canine region, the plate implant will be placed perpendicularly to the crest. When the amount of residual bone allows the creation of a bone pocket, the plate section will be inserted endosseously to provide primary stability, the arm section with holes will be fitted to and then screwed palatally into palatal cortical bone, and buccally the arm will be bent to 90° and fixed into the very compact bone of the lateral cortical bone of the canine pillar, providing secondary stability (Figs. 5.8 and 5.9). Fig. 5.8 Bending the buccal arm to 90° (14) Fig. 5.9 Insertion in the canine region (3) Hybrid plates are used in the molar and premolar regions of the maxilla, when there is very substantial bone resorption often combined with pneumatisation of the sinus; the height of the residual crest is often 0–3 mm. The longest part of these implants is subperiosteal, while they are endosseous at the crest. Two 7 mm osteosynthesis screws (true endosseous mini-implants) will give the implant primary stability, with one in the cortical bone of the zygomatic arch and the other in the cortical bone of the palatal arch. The recommandation is to cover the branches of the plate using bone recovered from drilling combined with other filling materials (BioOss®, Interpore®, Matribone etc) and a membrane. This covering layer will support the buccal mucosa at this level. In most situations, this reduces or completely eliminates the bulky artificial gingiva characteristic of dentures used for atrophic maxillae. The thinness of the plate makes it malleable, making it possible to fit the plate of the implant closely to the bone walls of the sinus. The implant is practically horizontal because of very substantial bone resorption in the maxilla (Fig. 5.10). Fig. 5.10 Fitting the plates onto a stereolithographic model and insertion in the zygomatic arch (3–4) Hengg-1 in place Hengg-1 and Hengg-2 in place Hengg-1 prepared Hybrid plates in the mandible These plates are designed to be inserted lengthways along the axis of the crest in the retromolar triangle region in patients with advanced recession of the mandibular crests and/or involvement of the tooth canal, which avoids a procedure to move the latter. The plate implants come in two widths (7 and 9 mm) and the number of holes may be adjusted to fit the space available, or they may be twisted to follow the shape of the bone. In this area, plates are inserted laterally if possible, in a bone “pocket” created for the purpose using an osteotome; so they are endosseous in some places and subperiosteal in others; 4–6 mm osteosynthesis screws are then fixed in cortical bone through the holes to provide stability (Fig. 5.11). Because of their lengthways position in the mandible, these plate implants must be combined with axial implants to minimize the impact of shear forces on them. Fig. 5.11 Placement of the implant in a bone pocket created for the purpose (14) 5. The Prosthesis in Cortically Fixed At Once In CF@O, the prosthesis has to satisfy a specific and very demanding list of specifications in terms of speed of execution and precision of the work. The effectiveness of the prosthetist and practitioner team is crucial to the success of the prosthesis, which in the end is the only visible and measurable part of cortical implantology. Immediate loading (within two weeks of insertion placement) is both an advantage and a requirement in cortical implantology; the prosthesis acts as a rigid external fixator for the implants, so ensuring optimal osseointegration. However, it is often better to include a stage of making a temporary resin prosthesis, to introduce occlusal loading of implants gradually and to visualize the amount of artificial gingiva required to compensate for any bone loss following the procedure, while retaining harmonious dental proportions. The final ceramic or zirconia prosthesis is manufactured after osseointegration has been checked, in 12–24 months. The frame supporting the prosthesis is manufactured in a single piece, and must provide good rigidity to the whole assembly. It is usually made of cobalt-chromium, with an L-shaped section and sufficient thickness (Fig. 6.2). The temporary prosthesis is screwed flat onto the implants, irrespective of their orientation. The two pterygoid implants are the most obvious representation with an orientation of 45° in the mesiodistal and buccolingual direction. Prosthetic protocol: (directly after suturing if the situation so allows, or the same day) (3, 9, 19, 12, 15) Place screwed-in transfers (pick-up transfers) onto the implant abutments Take an open impression (without impression tray) using DuraLay® resin (or other material with very low shrinkage). Inject light silicone (or alginate) around the implants and underneath the stabilizer bar; apply silicone putty to the rest of the arch, covering it completely (leaving space around the spaces for the screws) Impression with a closed tray may be used too. Record the VDO using a replica of the ideal assembly (or old denture if available) made of transparent resin filled with alginate in the inside of the arch on the healing abutments and wedged in occlusion with silicone. Cast the master model with extra hard stone analogues. Mount on an articulator using the occlusion model Cast the frame in rigid alloy with an L-shaped profile to increase resistance to bending. The inside of the framework arch is designed to take rings machined in titanium. This system of flat connectors allows the titanium connecting rings to be screwed flat so that they fit perfectly onto the head of the implants irrespective of axis (the titanium rings will be cemented in using special cement and will allow the prosthesis to be screwed-in uniformly while avoiding the corrosion related to using two different metals) (Fig. 6.2) Make a temporary prosthesis in resin with an artificial gingiva in contact with the crest. The bite model is made using a balanced occlusion method. A temporary prosthesis is screwed-in manually to 10 Ncm, the gold screws will be tightened again after 24 hours (about 1,000 bite cycles), the access holes will be filled with composite after the screw heads have been protected with wax or Teflon. Once implant osseointegration has been verified, the final prosthesis (in ceramic or cosmetic-grade zirconia) is made using the temporary prosthesis as a model (the frame may be kept or changed for another in zirconia, depending on the case) (Figs. 6.3 and 6.4). Fig. 6.1 Taking the pick-up impression (15) Fig. 6.2 L-profile Cr-Co framework (15) Figs. 6.3 and 6.4 Final zirconia bridge showing the titanium rings allowing the assembly to be screwed-in flat (15) 6. Conclusion For a long time, basal implantology was regarded as a risky procedure, but today there is a market increase in interest by both practitioners and patients attracted by its many benefits. As a result of all the hard work by the founders the discipline and its most experienced practitioners, Cortically Fixed at Once has a well-established protocol and offers reproducible results. This means that it can incorporate the whole range of treatment procedures available to the implantologist, and it has become a reliable alternative or addition to bone grafts in situations where there is substantial bone resorption. CF@O adapts to the volume of residual bone volume by exploiting it in all directions, thanks to the concept of tricortical support anchorage. With its foundations in the fundamental concepts of modern osseointegration, the contribution of orthopaedic surgery and clinical experience, CF@O today allows immediate loading with restoration of function and aesthetics within a few days for edentulous patients who used to be rejected for treatment. However, in spite of the contribution of modern imaging methods, the wide range of implants used, and the different specific insertion methods into the appropriate anatomic regions, Cortically Fixed at Once remains an essentially surgical discipline, requiring a long learning curve. https://www.corticallyfixed.com References 1. Scortecci G, Misch CE, Benner KU. Implants and Restorative Dentistry. London, UK: Martin Dunitz; 2001:79–85. 2. Misch CE, Qu Z, Bidez MW. Mechanical properties of trabecular bone in the human mandible. Implications of dental implant planning and surgical placement. J Oral Maxillofac Surg. 1999;57:700–706. 3. Misch CE. Contemporary Implant Dentistry. St Louis, Mo: Mosby Elsevier; 2008:1034–1035.Odin et al 4. Wilderman MN. Repair after a periosteal retention procedure. J Periodontol. 1963;34:487–503. 5. Frost HM. The biology of fracture healing: an overview for clinicians. Part I. Clin Orthop. 1989;248:283–293. 6. Axhausen W. The osteogenic phases of regeneration of bone: a historical and experimental study. J Bone Joint Surg Am. 1956;38:593–600. 7. Wolff J. The Law of Bone Remodeling. Berlin, Germany: Springer; 1986 [translation of the 1892 German edition]. 8. Urist MR. Bone formation by autoinduction. Science. 1965; 150:893–899. 9. Robling AG, Burr DB, Turner CH. Skeletal loading in animals. J Musculoskelet Neuron Interact. 2001;1:249–262. 10. Morgan EF, Longaker M, Carter DR. Relationships between tissue dilatation and differentiation in distraction osteogenesis. Matrix Biol. 2006;25:94–103. 11. Binderman I, Zor U, Kaye AM, Shisushoni Z, Harell A, Somjen D. The transduction of mechanical force into biochemical events in bone cells may involve activation of phospholipidase A2. Calcif Tissue Int. 1988;42:261–266. 12. Ingber DE. Mechanobiology and diseases of mechanotransduction. Review. Ann Med. 2003;35:564–577. 13. Ingber DE. Tensegrity: the architectural basis of cellular mechanotransduction. Ann Rev Physiol. 1997;59:575–599. 14. Suya H. Corticotomy in orthodontics. In: Hosl E, Baldauf A,eds. Mechanical and Biological Basics in Orthodontic Therapy. Heidelberg, Germany: Hu ¨tlig Buch; 1991:207–226. 15. Sebaoun JD, Kantarci A, Turner JW, et al. Modeling of trabecular bone and lamina dura following selective alveolar decortication in rats. J Periodontol. 2008;79:1679–1688. 16. Ilizarov GA. The tension stress effect on the genesis and the growth of tissues. Part II. The influence of the rate and frequency of distraction. Clin Orthopaed Rel Res. 1989b;239:263– 285. 17. Marx JL. Angiogenesis research comes of age. Science. 1987;237:23–24. 18. Doglioli P, Scortecci G. Characterization of endosteal osteoblasts isolated from human maxilla and mandible: an experimental system for biocompatibility tests. Cytotechnology. 1991;7:39–48. 19. Frost MH. The biology of fracture healing: an overview for clinicians. Part II. Clin Orthop. 1989;248:294–309. 20. Spiessl B. Internal Fixation of the Mandible: A Manual of AO/ ASIF Principles. New York, NY: Springer-Verlag; 1989: 68. 21. Branemark PI, Hansson BO, Adell R, et al. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg. 1977;16(suppl):1–132.

Yes, the installation of zygomatic implants by the Stella Technique is a Russian roulette. Perhaps you were lucky in your first cases where you followed the "success recipe" and had an excellent bone anchorage of the zygomatic implant in the body of the zygoma. However, randomness and probability will sooner or later be expressed, and you will install the zygomatic implant too far or even dangerously out of the ideal position, despite having strictly followed the technique. If you believe that this finding does not make sense, I invite you to read this post and then draw your own conclusions. The original technique for installing zygomatic implants proposed by Branemark recommended installing a totally intra-sinus zygomatic implant path. This hindered the surgical procedure and promotes a palatal displaced position prosthesis screw. Stella (1) proposed the Slot Technique for installing zygomatic implants. In this technique, we would have a possible improvement in the emergence of the prosthetic screw, a disposition of the antrostomy that can be obliterated by the implant installation itself, and a greater facility for the surgical execution technique. If we compare the Branemark technique, where the installation of the zygomatic implant was totally intra-sinus, the Stella Technique really was a significant advance and, in fact, facilitated the surgical approach. But there is a hazardous one. This attempt to create reproducible anatomical references to "facilitate" and standardize the surgical technique can cause significant problems in zygomatic implants' proper direction. The Stella Technique recommends the creation of a slot in the region of the zygomatic pillar. Following this slot, the zygomatic implant drill entrance into the body of the zygoma would happen naturally. In the image below, we can see the complete sequence, where initially the demarcations are made, the points are joined to create the slot, and in the sequence, the drill is introduced for drilling into the zygoma body until the complete exteriorization of the drill occurs through the outer bone cortical of the zygomatic bone body. The right direction of the drill following the slot may do happen, but it can also lead the surgeon to introduce the drill into the infratemporal fossa or even to perforate the posterior wall of the maxillary sinus. The violation of the infratemporal fossa can have several consequences and even some indications, and I explain this subject in more detail in this post. The surgical installation of the zygomatic implant without understanding this concept can be problematic. Perforation of the maxillary sinus's posterior wall and installing the zygomatic implant in this place makes the implant unstable and mobile when receiving pressure, even when it is osseointegrated. This is because the anchorage of the zygomatic implant in such cases is extremely low. Despite that, I received a patient in my clinic with rehabilitation with a zygomatic implant over 10 years old and complaining to the prosthetist that the zygomatic implant was swinging. Take a look at the right position of the zygomatic implant concerning the slot. It seems perfect. The surgeon strictly follows the principles of the Slot Technique. But, on CT scan, it was clear that the zygomatic implant installation was entirely outside the zygomatic bone! It was inside the infratemporal fossa, and both zygomatic implants were only osseointegrated in the thin cortical of the posterior wall of the maxillary sinus. In these cases, the treatment choice is to remove all implants and install new zygomatic implants with the proper planning and execution, placing the implants in maximum bone availability in the zygoma bone body. Many surgeons make the basic mistake of worrying too much about anchoring the zygomatic implant in the alveolar ridge region, the anterior wall of the maxillary sinus, and/or zygomatic buttress. Even with the anchorage of the zygomatic implant in this region, this anchorage is small, in most cases, negligible compared to the possibility of bone anchoring of the zygomatic implant in the zygomatic bone body. Stella's technique passes this false sensation to the surgeon, where filling the slot with the zygomatic implant gives us a feeling of increased bone anchorage, which is not always true. Another problem with the Stella Zygomatic Implant Technique. Believing that the Slot will always lead you to the region of maximum bone availability in the body of the zygoma bone is like believing that you can always install 8mm implants in the posterior part of the mandible because you read a review that said the average distance from the mandibular canal to the top of the crest is 7mm. You would be right in some cases and wrong in others. Using the Stella Technique, you are making use of that same way of thinking. The most important, and that needs to be repeated systematically, is that the zygomatic maxillary region's anatomy is hugely variable between individuals and even in the same individual. Following a "success recipe" when installing the zygomatic implant is like playing Russian roulette. It is not uncommon to install a totally extra-maxillary (extra-sinus) zygomatic implant on one side and the position of the zygomatic implant on the opposite side to follow a completely different path. The ideal position of the zygomatic implant is defined taking into account two factors: 1) the position of the zygomatic implant head in the region of the residual ridge 2) the area of maximum bone availability in the zygomatic bone body When these two factors are considered, it is clear that the personal choice of a specific technique is not possible, whatever it may be, but the patient's anatomy. It is easy to give a theoretical class on zygomatic implants based on theory only. But in practice, things are entirely different. The surgeon learns the Slot technique, and in his first zygomatic implant surgery, he could anchor the implant with an excellent bone insertion and high torque. So, he believes that he discovered the path to "infinite success," that he learned the infallible technique, and that from now on, just follow the same technique, and everything turns out just OK. He goes to the second surgery, follows the same technique, and his osteotomy falls entirely in the infratemporal fossa, and anxiety sets in. At that moment, he doesn't know what to do anymore because his foolproof technique proved to be fallible for the case in question. Guess how I learned this? Going through it all. It was there that the ZYGOMA 2.0 concept started to be developed. Most surgeons give up the zygomatic implant because they believe it is difficult and "not very predictable." In fact, they are victims of a flawed teaching process of the zygomatic implant technique. That is why we believe so much in need to expand the surgeon's way of thinking when it comes to zygomatic implant placement. It is essential not to be attached to dogmas based on medium distances or "all size fit all" formulas. Of course, planning in 3D software is more complicated; it takes work, mental energy, and time. It is much easier to follow a standard formula. It is easier just to take a look at the panoramic radiograph. However, the installation of a zygomatic implant is the most challenging procedure in implant dentistry. It is not for lazy surgeons. In the same way that orthognathic surgery was only predictable with virtual planning, the same can be said about zygomatic implants. Subsequently, installing externalized zygomatic implants (extra sinus technique) was introduced and brought a significant advance in installing zygomatic implants. But even so, the anatomy is what ends up telling us the best positioning of the implants. After understanding and experiencing this concept, we will see cases where it is totally possible to position the zygomatic implants completely outside the maxillary sinus. Still, already in others, the implants will be entirely inside the maxillary sinus, inevitably. The individualization of each case is essential. Merely choosing a technique and applying it in all cases does not make the least sense from a prosthetic, anatomical, and surgical point of view. The surgical procedure for installing a zygomatic implant is a science. You need to use technology to optimize results; otherwise, we could playing Russian roulette. And as we know, sooner or later, in Russian roulette, the worst will always come; it is only a matter of time. REFERENCES (1) Stella JP, Warner MR. Sinus slot technique for simplification and improved orientation of zygomaticus dental implants: a technical note. Int J Oral Maxillofac Implants. 2000 Nov-Dec;15(6):889-93. PMID: 11151591.

What are patients looking for? The patient has an extremely unstable upper denture and is looking for a solution to his problem. What does he seek, what does he imagine, and what is offered to him? In short, he seeks a solution to his problem. He does not seek surgery. Just keep in mind he is not a surgeon, and, unlike us, he does not like to see blood, surgical procedures, or pictures of dental implants. If there were a non-surgical alternative that could solve his problem, he would certainly choose it. But he already knows that it doesn't exist. He has already changed prostheses several times and even started using denture fixing creams, and nothing solves the problem as he expects. As all patients nowadays search for solutions on the internet, he already knows that, in such circumstances, the only alternative is a dental implant treatment. He already imagines and understands in advance that a surgical procedure will be necessary. Despite the fear, he decides to face the treatment, after all, it's just one surgery and everything will be just fine. He'll have his life back. Then he gets ready to evaluate with his trusted dentist to face this surgery procedure right away and solve his troublesome problem at once. He has researched possibilities like immediate loading and knows that in just a few days, or even on the same day, everything can be done. After the clinical and tomographic examination comes to the diagnosis: There is not enough bone in your upper jaw for the immediate installation of dental implants. It is another case of atrophic maxilla. There is no doubt in the surgeon's mind and the treatment method is automatically selected. Just like 2 +2 = 4, atrophic maxilla = bone graft. What is offered to him? Bone grafting. Not just one surgery, but at least three surgeries until the end of the treatment and more than one year of treatment (if everything turns out fine). But don't worry, Mr. Patient, I have many titles, and I am a great surgeon. I will show you how I can reconstruct your entire jaw, I have a lot of experience in advanced bone grafting surgery, and we can remove a piece of bone from your pelvis under general anesthesia and screw several blocks of bone in your whole upper jaw. It will be an incredible surgery! After limping and unable to use your dentures for several weeks, we will schedule a second surgery to install the dental implants and, after a couple of months, we will schedule the third surgery to reopen these implants, and we will start making your dream fixed full-arch rehabilitation. At this point, what is going on in the patient's head? Fear, disappointment, and deception. The initial courage to perform a surgery is overwhelmed by the news about the necessity of a bone graft procedure and at least three surgeries. Here is the mismatch: The patient seeks a solution and imagines one quick and straightforward surgery. The surgeon offers three surgeries, bone graft, weeks without using the denture, more than one year of treatment. But Doctor, are there any alternatives? Yes, there are! We have several bone graft alternatives! The problem of the "I have a hammer" approach From a legal point of view, the patient has the right to choose among the different treatment options. The professional knows about it and the range of options is sometimes open to the patient. However, in the case of the atrophic maxilla, several treatment possibilities are not usually offered, but just several bone graft possibilities. Mr. Patient, we have several options. We have several types of bone grafts that we could use. We can choose autogenous, allogeneic, xenogenous, or alloplastic bone, but there is no doubt and no treatment method except the bone graft! We all know that the gold standard is the autogenous bone graft, but morbidity and availability is a limitation of this modality. Biomaterials work well in the maxillary sinus, but for block use, we still need more evidence. Allogeneic bone, available in some countries, is not without risks(1,2). The lyophilization process does not entirely eliminate the immunogenic potential and may bring future problems to the patient. Regardless of the type of graft, the patient will always need to undergo at least three surgeries and more than one year of treatment. We all know that the patient has the right to know about all treatment alternatives, but when it comes to the atrophic maxilla, it is different. The bone graft has been presented with the only option. Why? It is the traditional mindset. A type of conduct that we can say is to treat atrophic maxilla thinking inside the box, following common sense, and omitting important information about the possibility of treating atrophic maxilla WITHOUT bone graft. For those who have a hammer in hand, every problem is a nail. It is prevalent to have two classes of surgeons. Those who hate zygomatic implants and those who love them. It is rare to find a middle ground. How is it possible, on the one hand, some surgeons having incredible results with zygomatic implants, rehabilitating atrophic jaws without bone graft and with immediate loading, to the point of using this technique as a routine in their clinical practice and, at the same time, having another group of surgeons who just don't want to hear about this type of implant? Often they do not even consider this possibility of treatment with their patients. But after all, if both are talking about the same technique, is this technique feasible or not? Is it predictable or not? Why so much variance of opinion? From a scientific point of view, there is a scale of evidence levels, where the lowest possible evidence is the level of personal opinion, and the top of the pyramid is the results of randomized clinical trials or systematic reviews and meta-analyses of randomized clinical trials. Therefore, if our objective is to offer our patients an evidence-based clinical practice, these discussions and divergence of personal opinions have a very low level of scientific validity and should never be taken into account in our decision-making process. When we go further to the top of the pyramid of evidence levels, we find that there are plenty of scientific studies corroborating with the high success rate of graftless rehabilitation techniques(3-15). In summary: the zygomatic implant is a highly predictable technique and promotes a substantial decrease in treatment time and patient satisfaction. This is the scientific truth that we have up to date. However, if you or any other surgeon has not yet convinced yourself about this, know that this is your personal opinion, and it has no scientific validity. In the recent past, the patient had only professional guidance regarding knowledge of all treatment possibilities, but this is not true today. The same scientific article available to you is also available to your patient. Nowadays, it is quite normal for patients coming to the dental office extremely well-oriented about treatment possibilities and with extremely advanced technical questions. In the case of atrophic jaws, it is increasingly common for patients to start looking for professionals focused on graftless rehabilitation. Great surgeons, minimally invasive surgeries There is a perception that at the beginning of an oral surgeon career, one learns basic implant dentistry. The dental implant is installed when there is a favorable availability of bone and soft tissues. At the level of basic implant dentistry, the focus is on acquiring basic knowledge, developing initial surgical skills; that is, the focus is on learning. However, this favorable condition does not always exist, and the professional begins to face more complex cases, such as, for example, cases of atrophic maxilla. He then sees himself in need to take advanced surgical training, that is, he needs to learn how also to perform bone graft procedures. At this stage, he feels superior in the hierarchy; he is at a high level; he is a surgeon who makes graft procedures. I remember my feeling at oral and maxillofacial surgical training when I did my first maxillary bone reconstruction using an iliac crest graft. I felt like a great surgeon. But for the patient, it was terrible. A large segment of the iliac crest was removed (much more than necessary for the maxilla graft). At hospital discharge, the patient could not even put his foot on the floor because of the pain he felt in his hip area. He had to go home in a wheelchair. Despite this, my ego as a great aspiring surgeon inflated, and I loved to tell other colleagues about the greatness of the surgery just performed. The ego only began to deflate when the patient, progressively, lost the implants one by one. Anyway, at this stage, it is common to focus on the surgeon, who, after all, wants to do big and complex surgeries. What we believe is that there is a stage above this level of the surgeon who performs bone graft. The highest level would be the surgeon who rehabilitates atrophic maxilla without bone graft. The big change happens when our focus shifts from the surgeon and goes to focus on the patient. We start to seek solutions in more predictable and less traumatic ways. It truly is a high level. It's here where the game change and, once you've tried this type of approach and its results, it's impossible to go back. There is no way to ignore graftless methods. Great surgeons, minimally invasive surgeries Less is more. And that was a great lesson that I learned during my Masters in Implant Dentistry at the University of Sagrado Coração in Baurú-SP. I came to Professor Dr. Carlos Eduardo Francischone with a tomography of an atrophic maxilla to explain my treatment planning and convince him that we could offer the patient an iliac crest graft. Assertively, lovingly and elegantly, he replies: "-Let's just tilt two implants in the posterior region and place two implants in the anterior part and immediately solve the patient's problem in a simple and fast way, and, under local anesthesia." At that time, I was formally introduced to the concept that would radically change the path of my clinical practice - The Allon4 concept. We did rehabilitate the patient with immediate loading, and, from there, my view of the atrophic maxilla was never the same. To further consolidate this view, Dr. Paulo Maló was presenting his doctoral thesis at that institution, and I had the opportunity to attend in person the nearly 5 hours of presentation and arguments from the board. My practice surrendered to the simplicity and sophistication of rehabilitation of atrophic maxilla without bone graft, and today, I have this as my main professional activity. Knowing these treatment possibilities, would the patient choose for bone graft? Are the clinical results the same as bone graft in the long run? Long-term 9 to 14 years follow-up studies show us a 90% survival rate for autogenous bone graft reconstructed maxilla implants(16). Not bad, but let's think about the patient's point of view. If I told him that there is a possibility to solve his problem with immediate load and with a 95% or higher chance of success in the long run, what would he choose? If Mother Nature presented us with a type of dense bone that provides us with an excellent anchorage, why look for them elsewhere using more invasive methods? Per-Ingvar Brånemark The focus on the patient makes us invariably think of techniques without bone graft. In addition to the benefits mentioned, this treatment philosophy brings us another positive side effect in our practice: we have a huge differential from competitors. Become a reference in your market In the business world, there is a term called Unique Selling Proposition, or USP. It refers to a differentiator that you have from your competitors. What would be a great USP? Focus on the patient! Remember: the patient seeks a single surgery, seeks immediate loading, wants a technique with a high success rate, and aesthetic longevity. Can we offer it all? Yes! It's a win-win treatment. The surgeon who learns how to rehabilitate atrophic jaws without bone graft quickly becomes a reference in his city and region. Over time, you will likely receive a patient from several states or even from other countries to be rehabilitated. Understand that: every surgeon who dominates the zygomatic implants technique also dominates the bone graft procedures, but not everyone who dominates the bone graft procedure dominates the zygomatic implants technique. Which group do you want to be part of? The first step in learning this treatment philosophy is to get rid of the old paradigms to which we have been exposed throughout our professional journey. That is what we will learn in this post. REFERENCES 1 de Lacerda, P. E. et al. Homologous transplantation with fresh frozen bone for dental implant placement can induce HLA sensitization: a preliminary study. Cell Tissue Bank 17, 465-472, doi:10.1007/s10561-016-9562-9 (2016). 2 Coutinho, L. F. et al. Presence of Cells in Fresh-Frozen Allogeneic Bone Grafts from Different Tissue Banks. Braz Dent J 28, 152-157, doi:10.1590/0103-6440201701206 (2017). 3 Malo, P., Rangert, B. & Nobre, M. All-on-4 immediate-function concept with Branemark System implants for completely edentulous maxillae: a 1-year retrospective clinical study. Clin Implant Dent Relat Res 7 Suppl 1, S88-94, doi:10.1111/j.1708-8208.2005.tb00080.x (2005). 4 Malo, P., de Araujo Nobre, M., Lopes, A., Moss, S. M. & Molina, G. J. A longitudinal study of the survival of All-on-4 implants in the mandible with up to 10 years of follow-up. J Am Dent Assoc 142, 310-320, doi:10.14219/jada.archive.2011.0170 (2011). 5 Grandi, T., Guazzi, P., Samarani, R. & Grandi, G. Immediate loading of four (all-on-4) post-extractive implants supporting mandibular cross-arch fixed prostheses: 18-month follow-up from a multicentre prospective cohort study. Eur J Oral Implantol 5, 277-285 (2012). 6 Malo, P., de Araujo Nobre, M., Lopes, A., Francischone, C. & Rigolizzo, M. "All-on-4" immediate-function concept for completely edentulous maxillae: a clinical report on the medium (3 years) and long-term (5 years) outcomes. Clin Implant Dent Relat Res 14 Suppl 1, e139-150, doi:10.1111/j.1708-8208.2011.00395.x (2012). 7 Malo, P., Nobre, M. & Lopes, A. Immediate loading of 'All-on-4' maxillary prostheses using trans-sinus tilted implants without sinus bone grafting: a retrospective study reporting the 3-year outcome. Eur J Oral Implantol 6, 273-283 (2013). 8 Babbush, C. A., Kanawati, A., Kotsakis, G. A. & Hinrichs, J. E. Patient-related and financial outcomes analysis of conventional full-arch rehabilitation versus the All-on-4 concept: a cohort study. Implant Dent 23, 218-224, doi:10.1097/ID.0000000000000034 (2014). 9 Ho, C. C. & Jovanovic, S. A. The "All-on-4" concept for implant rehabilitation of an edentulous jaw. Compend Contin Educ Dent 35, 255-259; quiz 260 (2014). 10 Chan, M. H. & Holmes, C. Contemporary "All-on-4" concept. Dent Clin North Am 59, 421-470, doi:10.1016/j.cden.2014.12.001 (2015). 11 Lopes, A., Malo, P., de Araujo Nobre, M. & Sanchez-Fernandez, E. The NobelGuide(R) All-on-4(R) Treatment Concept for Rehabilitation of Edentulous Jaws: A Prospective Report on Medium- and Long-Term Outcomes. Clin Implant Dent Relat Res 17 Suppl 2, e406-416, doi:10.1111/cid.12260 (2015). 12 Malo, P., de Araujo Nobre, M., Lopes, A., Ferro, A. & Gravito, I. All-on-4(R) Treatment Concept for the Rehabilitation of the Completely Edentulous Mandible: A 7-Year Clinical and 5-Year Radiographic Retrospective Case Series with Risk Assessment for Implant Failure and Marginal Bone Level. Clin Implant Dent Relat Res 17 Suppl 2, e531-541, doi:10.1111/cid.12282 (2015). 13 Malo, P., de Araujo Nobre, M. A., Lopes, A. V. & Rodrigues, R. Immediate loading short implants inserted on low bone quantity for the rehabilitation of the edentulous maxilla using an All-on-4 design. J Oral Rehabil 42, 615-623, doi:10.1111/joor.12291 (2015). 14 Najafi, H., Siadat, H., Akbari, S. & Rokn, A. Effects of Immediate and Delayed Loading on the Outcomes of All-on-4 Treatment: A Prospective Study. J Dent (Tehran) 13, 415-422 (2016). 16 Nystrom, E., Nilson, H., Gunne, J. & Lundgren, S. A 9-14 year follow-up of onlay bone grafting in the atrophic maxilla. Int J Oral Maxillofac Surg 38, 111-116, doi:10.1016/j.ijom.2008.10.008 (2009).

"The No BS Concept" of the Allon4 technique was written for surgeons, for those who face atrophic jaw from a different perspective. If you do believe that the bone graft is the unique treatment option for atrophic maxilla, you could stop reading here. Otherwise, keeping reading and welcome to the more straightforward guide about Allon4 ever published. Simplicity is the maximum degree of sophistication. Leonardo da Vinci Yes, the Allon4 is a simplified technique, but it is not simple. What we will see later are practical concepts of those who do what they teach and not just replicate what they've read. It is possible to theorize, dive into the preambles of finite element analysis studies, biomechanics, clinical studies, peri-implant bone remodeling, among other factors. All this information is published and serves as a scientific basis for us to be able to execute the technique with a strong scientific basis. We will see it only superficially. If, for you, at this very moment, the most important thing is to fully master all this theoretical information, feel free to read all these articles that are available to you elsewhere. But assuming that all of this publication do exist and what you want is to implement the result of it in your clinical practice, read on. The objective of the Allon4 technique is to use only four implants strategically placed in regions of high bone density, enabling immediate loading. The tendency of bone quality is quite different in distinct areas of the maxillofacial sites. We all know that bone density is one of the main factors responsible for high insertion torques of dental implants and consequently allowing us to perform the immediate load safely. It is a predictable feat in the lower jaw because it is a movable bone with insertions of the powerful masticatory muscles, which stimulates bone corticalization. In the maxilla, the challenge is more remarkable, especially when the dental implants are installed in a region of grafted bone or posterior part of it. It is because the maxilla is a fixed bone, and only insertions of the mimic facial muscles are attached to it. Despite it, there are areas of dissipation of masticatory force where there is a tendency towards greater corticalization. These areas are located in the nasomaxillary, canine, and zygomaticomaxillary buttress regions. It is precisely in these regions where rigid internal fixations are performed to stabilize Le Fort I type fractures (either due to trauma or orthognathic surgery). Zygomatic bone, on the other hand, has a peculiar characteristic. Despite being a fixed bone, it has the insertion of the most potent masticatory muscle - the masseter. It causes a high trend of corticalization in its insertion. Even after the loss of all teeth with consequent alveolar resorption, the stimulus to the masseter muscle will always be present. When it comes to bone consistency, the zygomatic bone is a kind of mandible bone in the middle third of the face. It is the main reason for the high insertion torques in this bone. Anyone who has never had a zygomatic implant surgery has a false feeling that this implant is unstable and, therefore, can cause damage to the future prosthesis. Only after feeling in practice the insertion torque and the final stability of an installed zygomatic implant, the surgeon started to believe what he has read. The basis of the Allon4 concept is to prioritize the quality of the implants over the quantity of it. This better-quality bone will be present in the anterior region of the maxilla and through the whole zygomatic bone(1). There are three basic modalities to rehabilitate atrophic maxilla without bone graft within the Allon4 concept, which will be indicated according to the bone availability of each case. Allon4 types Allon4 Standard. In this modality, we will install four normal implants in the anterior region of the maxilla. It is indicated when we have remaining bone below the piriform aperture and canine buttress region. The distal implants need to be tilted around 45o tangent to the anterior wall of the maxillary sinus, and the emergence of the prosthetic screw will generally come out at the level of the 1st upper premolar or posterior. The central implants are installed using a palatal approach. When we do not have the available bone structure to install these distal implants, but there is a condition to place two implants in the anterior region, usually adjacent to the incisive foramen, we will use the Allon4 Hybrid modality, where we will associate two zygomatic implants to these two central implants. Take a look at this post to know everything about zygomatic implants systems. In cases of severe atrophy where there is no possibility of installing implants on maxilla, we will use the Allon4 Zygoma modality, where four zygomatic implants are placed in the zygomatic bone (quad zygoma). When you perform zygomatic implants but do not understand the Allon4 philosophy, you often overtreat the patient, install zygomatic implants in cases that could be resolved with conventional tilted implants (Allon4 Standard). Finally, understand that the patient is not interested in surgery; he wants to be rehabilitated with an aesthetic and functional implant-supported prosthesis. We should always put the patient first and think that if I can solve the case with Allon4 Standard surgery, why am I going to perform Allon4 Hybrid? Just to share one more case of the zygomatic implant on the Facebook group? Patient first, surgeon later. If it is possible to simplify, do not complicate it. Take the phrase from my master prof. Carlos Eduardo Francischone and take this as a mantra in your planning - just put four implants (Allon4 standard) and solves the patient's problem soon. It is the basis of the ZYGOMA 2.0 concept. Case selection for a zygomatic implant with extreme caution and responsibility. Once indicated, we will learn to plan and perform with maximum safety and results for our patients. From a marketing point of view, it is effortless to acquire new patients. Generally, these patients have already been evaluated by other professionals, and, most of the time, all of them spoke only about bone graft. You then propose to carry out the treatment without bone graft and with immediate loading, and certainly, this is a great differential. It's a kind of win-win treatment. If we could say what the core, the essence, the heart of the Allon4 Standard technique is, I would say there are three pillars: the palatal approach; learn to position the posterior implants on the anterior wall of the maxillary sinus; and maintain the spatial relationship of the initial perforation with the center of the face. Also, we have to take into account that the costs for the patient end up also being lower(2). We will now dive into the Allon4 Standard Technique. You will now understand some technical details that will make a massive difference in the surgery and consequently, in your clinical results. Allon4 Standard If we could say what the core, the essence, the heart of the Allon4 Standard technique is, I would say there are three pillars: the palatal approach; learn to position the posterior implants on the anterior wall of the maxillary sinus and maintain the spatial relationship of the initial perforation with the center of the face. If we could say what the core, the essence, the heart of the Allon4 Standard technique is, I would say there are three pillars: the palatal approach; learn to position the posterior implants on the anterior wall of the maxillary sinus, and maintain the spatial relationship of the initial perforation with the center of the face. Palatal approach After understanding this concept and experiencing it in practice, you will never look at an atrophic maxilla the same way again. There is an automatic impulse always to imagine implants being installed in the center of the alveolar bone crest. When the crest bone is thin, a bone graft is suggested, usually in a block. However, with the palatal approach, we will install the implants by drilling the palatal cortical, paying attention so that no vestibular fenestrations occur, and we will leave the palatal cervical threads of the implant exposed. But won't that be a problem? Not!3 Because the palatal mucosa is exceptionally thick, dense, and keratinized, there is no tissue dehiscence. Exemplifying. Imagine a situation like this below. The "standard" planning would undoubtedly include at least a bilateral maxillary sinus lift and even block grafting in the anterior region. After wanting 6 to 8 months, installation of 6 to 8 implants. After the period of osseointegration, new incision to expose de implants and then the procedures to the final prosthesis. Anyway, three surgeries and more than one year of treatment. But using the Allon4 concept, you will understand that the most central region in yellow is the region where there is a tendency to have a denser bone. The red part represents the place where the bone tends to be less dense. You will then start the drilling process in the region of less dense bone and progress with the drilling, preferably until the drill transfixes the cortical of the floor of the nasal cavity. That's right! There is no complication in this maneuver, but the fact that the implants being bicorticalize, especially when the bone height is reduced, can be the decisive factor between a high or low insertion torque of the implant. In addition to these implants being installed in a region of greater bone density, it is prevalent to use longer distal implants, usually 17mm length. Whenever I teach face-to-face classes, at that point in the class, a question always arises. - But professor, will not be tilting these implants promote bone loss? The answer is: NO! Several studies are supporting that there is no bone loss in these tilted implants(4-12). Understand: Decreasing the cantilever is more important than keeping the implants straight. But the most common question from patients (and also from professionals who do not know the Allon4 technique) is: - Doctor, but only with four implants, does it work? Another dentist said that only four implants are dangerous because if I lose one implant, I will lose the entire rehabilitation, so it is better to place several more implants. When implants are installed in grafted bone, it is common to lose some implants, so the strategy is to place as many as possible, around 6 to 8 implants. Some implants will be lost, and what is left is then used to anchor the prosthesis. However, when we talk about Allon4, we are placing the implants in non-augmented bone, that is, bone that is well vascularized, alive, and of higher quality. Osseointegration is a qualitative question of anchorages and not a quantitative one. A study by Professor Brånemark published in 1995(13) evaluates the rehabilitation with 4, 5, or 6 implants. The patients were followed for 10 years. The result was that there was no statistical difference between the groups evaluated. The studies of the Allon4 technique started in the early 90s, with the first case being performed in the mandible in 1993. The benefits of the decrease in the cantilever were found and a high success rate. In 1996, it was conducted in the maxilla, and they started to have a lower success rate. It drops to only 70%. Then the possible causes and solutions to optimize success in the maxilla began to be investigated. The design of the dental implant was modified, where the Nobel Speedy™ implant was launched. The benefits of seeking bicorticalizations (on the floor of the nasal cavity and anterior wall of the maxillary sinus) and the concept of sub-drilling were established to promote osseocompression during implant installation and optimize insertion torque. Anyway, it took ten years to structure the protocol, and from there, the cases were selected for scientific validation. Sequentially, studies and evidence appeared, and, at the present date, we have a lot of literature supporting us for the success and predictability of this technique(2,7,8,13-33). But the advantages of the Allon4 technique do not end there. We all know that the minimum distance between implants must be at least 3mm to minimize the chance of saucerization. When 6 to 8 implants are installed, according to the traditional protocol, sometimes there may be a decrease in the distance between these implants, which is not ideal. In addition to potential damage to peri-implant tissue stability, such situations generate numerous areas between implants for the patient to floss, making it very difficult to clean these spaces. See below when using just four implants, the time and ease of cleaning are much better. The biomechanics of the future prosthesis are greatly improved when the cantilever is decreased by the inclination of the distal implants(4-12). In the mandible, in most cases, it is possible to arrange the implant head above the mental foramen, and due to the tilting of these distal implants, it is also possible to use longer implants and still deviate from the mental nerve looping. The passivity of the metal infrastructure of the prosthesis also tends to be easier when fewer implants are used. A simple example, which can be explained to the patient, would be to compare the stability of a table with four legs compared to a table with six legs. The latter tend to have more difficulty in attaining stability. Sub instrumentation (under preparation osteotomy) This strategy is common in implant surgery. In the Allon4 technique, it is taken very seriously. To install implants with a thickness of 3.75mm, we usually drill with the pilot drill, drill 2.0, a little bit of the pilot drill 2/3, and, depending on bone consistency, drill 2.8.mm. The implant design must be optimized for osseocompression. Ideally, it should have an active tip, such as a NobelSpeedy™ or NeodentEx™ implant, among many others available on the market. In the preoperative sequence and prosthetic preparation, there is no difference concerning conventional protocols. Preoperative exams are routinely requested, reverse prosthetic planning is performed, and a complete prosthesis is made within the aesthetic and functional parameters. This prosthesis can be used immediately as a temporary prosthesis, capturing that prosthesis on the titanium cylinders, or we can use it as a multifunctional guide and make the prosthesis with a metal infrastructure. After three months, if necessary, a reshaping can be done on the bottom of the prosthesis for a better relationship with the already healed soft tissues. Does the immediate loading need to finish in 3 days? There has always been this concern in the past. It was believed that it was necessary to splint these implants as early as possible. I have realized in practice that this is not the case. We used to remove the prosthesis routinely to remove the suture in 7 days, and we never had any problems because of that. We have to understand that the implants were locked with 35 Ncm or more and, despite the torque dropping in the postoperative period, to remove and reinstall the prosthesis, we will give a torque of only 10 Ncm on the prosthesis cylinder screw. There is even a study that reports that there are no differences between the different types of protocols for immediate loading(8). As our confidence in the technique has increased over the years, even in cases of low torque in some implants, we continue to maintain immediate loading, and this has not reduced our success rate. I have always believed that torque (turning) does not occur with the prosthesis in function, besides the union of all components acting as a whole system. More recently, our clinical perception was as well perceived for others, which just published it, where it was evident that low insertion torques do not decrease the success rate(28). Now let's look at the technical and clinical concepts for carrying out the standard Allon4 technique. Bone leveling After local anesthesia, incision (positioned more towards the palate), and total mucoperiosteal detachment, we must make a bone leveling. This leveling can be almost zero, just smoothing the sharp edges of the residual edge, or it can be quite bulky. How to define the magnitude of this cut? As we are going to perform dentogingival prosthesis, the transition from artificial gums to natural gums must not be exposed during the smile. Because of this, the essential picture you should take in the preoperative period is an image of the patient smiling without the denture. It is possible to evaluate and record the dynamics of the lip and quantify how much bone and gingival tissue will be necessary to remove at the time of surgery. This lack of leveling can also leave little space for the bar, pink resin and teeth, causing the prosthesis to have vestibular overextensions (such as small flanges), which makes the ability to maintain proper oral hygiene difficult. In some patients, the vertical leveling of the ridge will be done up to the maximum limit, which, in the posterior region of the maxilla, will be until we find a bluish part that is the maxillary sinus. An essential tip for you not to lose the reference of how much bone you have already removed with what you need to remove is to wear one hemiarch at a time, so the other hemiarch remains with reference. Facial reference guide Initial drilling reference The establishment of spatial orientation is critical. If you lose your spatial reference of the perforations to the face, you can completely lose the three-dimensional control of the position of the implants. In the image below, our student installed the straight central implants and tilted the distal implants. Then he called me to see if she could continue with the drilling. In her view, the initial perforations were accurate. However, when we zoom out and see the patient's face as a whole, it is clear that the central implants are tilted to the left. This lack of spatial orientation is widespread in those at the beginner level. Such an error in the maxilla can make it very difficult to correctly position the distal implants. How to avoid mistakes like that? We have two ways to stay spatially oriented during surgery: 1) Parallel pins We are all used to using these straight pins. However, there are also these pins with angles of 17o and 30o. 2) Allon4 Guide It is a specific Allon4 implant placement guide marketed by Nobel™. After doing the initial drilling and installing the parallelize pin, you need to move away from the operating field and look at the patient's face from the front. Being ok, just move on, otherwise, just adjust. Getting it right is critical. It is through this reference that all other implants will be installed. A vital tip to facilitate the initial drilling with the palatal approach is to invert the position of the handpiece and look at the maxilla from the bottom up. The drilling with the operator at 9 hours position does not give us an excellent spatial relation and an exact notion of parallelism. With the initial perforations made, we will use the 2.0mm drill that will be deepened until we fall into the void, that is, until we feel that we have completed passed through the nasal cavity cortical floor. With the aid of a probe, we will precisely measure the size of the implant that we will be using. Be aware that, in general, if you have drilled until you fall into the nasal cavity and in your measurement, you have identified that the implant is more than 13mm, you have likely leveled the ridge too little. In this case, level the ridge more and use a maximum 13mm implant. Drilling the distal implants will be performed at 45o to previous implants. Even when the bone is available in the posterior region of the maxilla, there is a strong tendency for this bone to be of low quality. Another way to orient yourself spatially is through the Nobel™ Allon4 drilling guide. After the initial drilling, you will install this guide and see how it is positioned concerning the face and whether it is perpendicularly positioned with the bipupilar plane. This guide is flexible, and you can shape it according to the shape of the ridge and adjust the tilt in the sagittal direction. In this guide, there are vertical lines that will serve as a reference for the installation of central and distal tilted implants. The most critical point for performing the Allon4 technique is the installation of posterior implants. Understanding how to drill these implants on the anterior wall of the maxillary sinus is an important maneuver. There are some strategies for this, and we will see it next. How to tangent the anterior wall of the maxillary sinus Where do we place the initial perforations of the distal implants? In many cases, it is possible to identify a slight bony prominence of the canine buttress. If the canine tooth were in this region in the past, it means that if we enter our drill distally to this bony prominence, it is very likely that the emergence of the prosthetic screw will come out very close to the upper 1st premolar. The apical direction of the drilling, in most cases, can be towards the parallel pin of the anterior implant because we know that in this region, undoubtedly, there is bone. If you want to check the position of the initial perforations with the surgical guide (multifunctional guide), you can then use the angled guide pins of 30o (or 17o if you have not tilted too much the implants). The drill sequence to be used will vary according to bone density and your tactile perceptions, always taking care to perform a sub-drilling. How to tangent the anterior wall of the maxillary sinus There are four strategies to do that: 1) For transparency Immediately after total mucoperiosteal detachment, it might be possible to identify a more bluish region on the outer wall in the posterolateral part of the maxilla. It happens because of the thin thickness of the lateral bony lamina of the maxillary sinus. In such situations, it is easy to define the anterior limit of the maxillary sinus visually. 2) Drilling and probing In cases where the outer cortical bone is thicker, and it is not possible to see a bluish region, we can make a small lateral opening in the maxillary sinus. We can use a probe or curette to touch where the anterior limit of the maxillary sinus is found. As we will not be placing particulate bone, there are no concerns regarding the integrity of the sinus membrane. 3) Post-extraction socket reference When there are associated extraction procedures, it is possible to use the references of the position of the alveoli with surrounding bone availability so that we can define the position where it is possible to make the perforations. 4) Tactile perception After the installation of the anterior implants, you can measure according to the tomographic exam and make the initial perforation inclined to the anterior one and notice if you have found bone resistance during the entire perforation or felt a sensation of "falling into the void" inside the maxillary sinus. If you have fallen into the void, you have to change the direction of the perforation toward the anterior until you find bone resistance. Does the order of dental implants interfere with the result? It could be yes or it could be no. When there is enough bone, the implants are far from each other, and the tip of these implants is not likely to touch each other. However, in borderline cases, the order of the implants can make a difference. The distal implants are generally more critical and should have priority. The anterior implants, in the worst case, we can even empty the content of the incisive canal to install one of the implants. Imagine that we have already installed two 11mm implants in the central region, and now we are going to drill the distal ones. It may be that one of these central implants made it impossible to install a distal implant with the desired size. It was what happened in the case below, where I had to change the planning in the trans-surgical moment and put a smaller implant on the left side. So, when in doubt, leave the drills in position and make a probe to identify if there is a touch between the implants before to finish drilling. Installation of prosthetic components. As the distal implants are very tilted, we will use 30o angled mini abutments to compensate for these inclinations. However, it is prevalent for you to have difficulty fitting the mini-abutment because it usually ends up touching the bone surrounding the implant head. For this reason, after finishing the preparation of the bone bed, I suggest that you wear the region where the implant head will be a little more. As much as you use the countersink drill, it still doesn't seem to be enough in most cases. It is essential to make sure that the mini abutment is seated correctly during the installation otherwise, you may have some surprise on the control radiograph. In the next post, I will cover some more clinical tips about Allon4 Standard. But before move forward, I would like to hear your opinion in the comments below. Click here for The "No BS Guide" to All-on-4 Technique (Part II) REFERENCES 1 Bertl, K. et al. MicroCT-based evaluation of the trabecular bone quality of different implant anchorage sites for masticatory rehabilitation of the maxilla. J Craniomaxillofac Surg 43, 961-968, doi:10.1016/j.jcms.2015.04.008 (2015). https://pubmed.ncbi.nlm.nih.gov/26027862/ 2 Babbush, C. A., Kanawati, A., Kotsakis, G. A. & Hinrichs, J. E. Patient-related and financial outcomes analysis of conventional full-arch rehabilitation versus the Allon4 concept: a cohort study. Implant Dent 23, 218-224, doi:10.1097/ID.0000000000000034 (2014). https://pubmed.ncbi.nlm.nih.gov/24394342/ 3 Lekholm, U., Sennerby, L., Roos, J. & Becker, W. Soft tissue and marginal bone conditions at osseointegrated implants that have exposed threads: a 5-year retrospective study. Int J Oral Maxillofac Implants 11, 599-604 (1996). https://pubmed.ncbi.nlm.nih.gov/8908857/ 4 Cucchi, A. et al. Evaluation of Crestal Bone Loss Around Straight and Tilted Implants in Patients Rehabilitated by Immediate-Loaded Full-Arch Allon4 or All-on-6: A Prospective Study. J Oral Implantol 45, 434-443, doi:10.1563/aaid-joi-D-18-00152 (2019). https://pubmed.ncbi.nlm.nih.gov/31536710/ 5 Hopp, M., de Araujo Nobre, M. & Malo, P. Comparison of marginal bone loss and implant success between axial and tilted implants in maxillary Allon4 treatment concept rehabilitations after 5 years of follow-up. Clin Implant Dent Relat Res 19, 849-859, doi:10.1111/cid.12526 (2017). https://pubmed.ncbi.nlm.nih.gov/28766312/ 6 Liu, T., Mu, Z., Yu, T., Wang, C. & Huang, Y. Biomechanical comparison of implant inclinations and load times with the Allon4 treatment concept: a three-dimensional finite element analysis. Comput Methods Biomech Biomed Engin 22, 585-594, doi:10.1080/10255842.2019.1572120 (2019). https://pubmed.ncbi.nlm.nih.gov/30821483/ 7 Lofaj, F., Kucera, J., Nemeth, D. & Mincik, J. Optimization of Tilted Implant Geometry for Stress Reduction in Allon4 Treatment Concept: Finite Element Analysis Study. Int J Oral Maxillofac Implants 33, 1287-1295, doi:10.11607/jomi.6371 (2018). https://pubmed.ncbi.nlm.nih.gov/30427959/ 8 Najafi, H., Siadat, H., Akbari, S. & Rokn, A. Effects of Immediate and Delayed Loading on the Outcomes of Allon4 Treatment: A Prospective Study. J Dent (Tehran) 13, 415-422 (2016). https://pubmed.ncbi.nlm.nih.gov/28243303/ 9 Ozan, O. & Kurtulmus-Yilmaz, S. Biomechanical Comparison of Different Implant Inclinations and Cantilever Lengths in Allon4 Treatment Concept by Three-Dimensional Finite Element Analysis. Int J Oral Maxillofac Implants 33, 64-71, doi:10.11607/jomi.6201 (2018). https://pubmed.ncbi.nlm.nih.gov/29340344/ 10 Sannino, G. Allon4 concept: a 3-dimensional finite element analysis. J Oral Implantol 41, 163-171, doi:10.1563/AAID-JOI-D-12-00312 (2015). https://pubmed.ncbi.nlm.nih.gov/23560570/ 11 Shahriari, S. et al. The Effect of Mandibular Flexure on Stress Distribution in the Allon4 Treated Edentulous Mandible: A Comparative Finite-Element Study Based on Mechanostat Theory. J Long Term Eff Med Implants 29, 79-86, doi:10.1615/JLongTermEffMedImplants.2019030866 (2019). https://pubmed.ncbi.nlm.nih.gov/31679205/ 12 Takahashi, T., Shimamura, I. & Sakurai, K. Influence of number and inclination angle of implants on stress distribution in mandibular cortical bone with Allon4 Concept. J Prosthodont Res 54, 179-184, doi:10.1016/j.jpor.2010.04.004 (2010). https://pubmed.ncbi.nlm.nih.gov/20452854/ 13 Branemark, P. I., Svensson, B. & van Steenberghe, D. Ten-year survival rates of fixed prostheses on four or six implants ad modum Branemark in full edentulism. Clin Oral Implants Res 6, 227-231, doi:10.1034/j.1600-0501.1995.060405.x (1995). https://pubmed.ncbi.nlm.nih.gov/8603114/ 14 Malo, P., Rangert, B. & Nobre, M. Allon4 immediate-function concept with Branemark System implants for completely edentulous maxillae: a 1-year retrospective clinical study. Clin Implant Dent Relat Res 7 Suppl 1, S88-94, doi:10.1111/j.1708-8208.2005.tb00080.x (2005). https://pubmed.ncbi.nlm.nih.gov/16137093/ 15 Malo, P., de Araujo Nobre, M., Lopes, A., Moss, S. M. & Molina, G. J. A longitudinal study of the survival of Allon4 implants in the mandible with up to 10 years of follow-up. J Am Dent Assoc 142, 310-320, doi:10.14219/jada.archive.2011.0170 (2011). https://pubmed.ncbi.nlm.nih.gov/21357865/ 16 Grandi, T., Guazzi, P., Samarani, R. & Grandi, G. Immediate loading of four (Allon4) post-extractive implants supporting mandibular cross-arch fixed prostheses: 18-month follow-up from a multicentre prospective cohort study. Eur J Oral Implantol 5, 277-285 (2012). https://pubmed.ncbi.nlm.nih.gov/23000711/ 17 Malo, P., de Araujo Nobre, M., Lopes, A., Francischone, C. & Rigolizzo, M. "Allon4" immediate-function concept for completely edentulous maxillae: a clinical report on the medium (3 years) and long-term (5 years) outcomes. Clin Implant Dent Relat Res 14 Suppl 1, e139-150, doi:10.1111/j.1708-8208.2011.00395.x (2012). https://pubmed.ncbi.nlm.nih.gov/22008153/ 18 Malo, P., Nobre, M. & Lopes, A. Immediate loading of 'Allon4' maxillary prostheses using trans-sinus tilted implants without sinus bone grafting: a retrospective study reporting the 3-year outcome. Eur J Oral Implantol 6, 273-283 (2013). https://pubmed.ncbi.nlm.nih.gov/24179981/ 19 Ho, C. C. & Jovanovic, S. A. The "Allon4" concept for implant rehabilitation of an edentulous jaw. Compend Contin Educ Dent 35, 255-259; quiz 260 (2014). https://pubmed.ncbi.nlm.nih.gov/24773251/ 20 Chan, M. H. & Holmes, C. Contemporary "Allon4" concept. Dent Clin North Am 59, 421-470, doi:10.1016/j.cden.2014.12.001 (2015). https://pubmed.ncbi.nlm.nih.gov/25835803/ 21 Lopes, A., Malo, P., de Araujo Nobre, M. & Sanchez-Fernandez, E. The NobelGuide Allon4 Treatment Concept for Rehabilitation of Edentulous Jaws: A Prospective Report on Medium- and Long-Term Outcomes. Clin Implant Dent Relat Res 17 Suppl 2, e406-416, doi:10.1111/cid.12260 (2015). https://pubmed.ncbi.nlm.nih.gov/27758069/ 22 Malo, P., de Araujo Nobre, M., Lopes, A., Ferro, A. & Gravito, I. Allon4 Treatment Concept for the Rehabilitation of the Completely Edentulous Mandible: A 7-Year Clinical and 5-Year Radiographic Retrospective Case Series with Risk Assessment for Implant Failure and Marginal Bone Level. Clin Implant Dent Relat Res 17 Suppl 2, e531-541, doi:10.1111/cid.12282 (2015). https://pubmed.ncbi.nlm.nih.gov/25536438/ 23 Malo, P., de Araujo Nobre, M. A., Lopes, A. V. & Rodrigues, R. Immediate loading short implants inserted on low bone quantity for the rehabilitation of the edentulous maxilla using an All on 4 design. J Oral Rehabil 42, 615-623, doi:10.1111/joor.12291 (2015). https://pubmed.ncbi.nlm.nih.gov/25757870/ 24 Tallarico, M. et al. An up to 7-Year Retrospective Analysis of Biologic and Technical Complication With the Allon4 Concept. J Oral Implantol 42, 265-271, doi:10.1563/aaid-joi-D-15-00098 (2016). https://pubmed.ncbi.nlm.nih.gov/26652901/ 25 Li, S., Di, P., Zhang, Y. & Lin, Y. Immediate implant and rehabilitation based on Allon4 concept in patients with generalized aggressive periodontitis: A medium-term prospective study. Clin Implant Dent Relat Res 19, 559-571, doi:10.1111/cid.12483 (2017). https://pubmed.ncbi.nlm.nih.gov/28371086/ 26 Lopes, A., Malo, P., de Araujo Nobre, M., Sanchez-Fernandez, E. & Gravito, I. The NobelGuide All on 4 Treatment Concept for Rehabilitation of Edentulous Jaws: A Retrospective Report on the 7-Years Clinical and 5-Years Radiographic Outcomes. Clin Implant Dent Relat Res 19, 233-244, doi:10.1111/cid.12456 (2017). https://pubmed.ncbi.nlm.nih.gov/25195544/ 27 Brignardello-Petersen, R. High proportion of implant and prostheses survive after 5 years in patients treated with the All on 4 strategy in the maxilla. J Am Dent Assoc 149, e38, doi:10.1016/j.adaj.2017.10.021 (2018). https://pubmed.ncbi.nlm.nih.gov/29174277/ 28 Malo, P., Lopes, A., de Araujo Nobre, M. & Ferro, A. Immediate function dental implants inserted with less than 30N.cm of torque in full-arch maxillary rehabilitations using the Allon4 concept: retrospective study. Int J Oral Maxillofac Surg 47, 1079-1085, doi:10.1016/j.ijom.2018.04.008 (2018). https://pubmed.ncbi.nlm.nih.gov/29735198/ 29 Malo, P. S., de Araujo Nobre, M. A., Ferro, A. S. & Parreira, G. G. Five-year outcome of a retrospective cohort study comparing smokers vs. nonsmokers with full-arch mandibular implant-supported rehabilitation using the Allon4 concept. J Oral Sci 60, 177-186, doi:10.2334/josnusd.16-0890 (2018). https://pubmed.ncbi.nlm.nih.gov/29743383/ 30 Abdou, E. M., Elgamal, M., Mohammed Askar, O. & Youssef Al-Tonbary, G. Patient satisfaction and oral health-related quality of life (OHRQoL) of conventional denture, fixed prosthesis and milled bar overdenture for Allon4 implant rehabilitation. A crossover study. Clin Oral Implants Res 30, 1107-1117, doi:10.1111/clr.13524 (2019). https://pubmed.ncbi.nlm.nih.gov/31410893/ 31 Malo, P., de Araujo Nobre, M., Lopes, A., Ferro, A. & Botto, J. The Allon4 treatment concept for the rehabilitation of the completely edentulous mandible: A longitudinal study with 10 to 18 years of follow-up. Clin Implant Dent Relat Res 21, 565-577, doi:10.1111/cid.12769 (2019). https://pubmed.ncbi.nlm.nih.gov/30924309/ 32 Malo, P., de Araujo Nobre, M., Lopes, A., Ferro, A. & Nunes, M. The Allon4 concept for full-arch rehabilitation of the edentulous maxillae: A longitudinal study with 5-13 years of follow-up. Clin Implant Dent Relat Res 21, 538-549, doi:10.1111/cid.12771 (2019). https://pubmed.ncbi.nlm.nih.gov/30924250/

Along with the post The "No BS Guide" to Allon4 Technique (Part I), we have seen a lot of technical concepts about the Allon4 technique. Let dive into the clinical and surgical concepts Surgical technique All-on-4 standard - Technical concepts The local anesthesia can be done with the same technique as for a conventional protocol surgery. We are going to block the infraorbital nerve, upper posterior and middle alveolar nerves, nasopalatine and greater palatine nerves and/or infiltrative anesthesia at the vestibule sulcus. The incision is made with the flap design more palatal to the ridge crest center so that we can have a greater amount of keratinized gingiva around the mini abutments. Two vertical incisions are made in the region of the zygomatic buttress. The detachment is done in the usual way with the elevator, Freer, Molt surgical curette or similar, according to your preference. The nasopalatine nerve can be sectioned to facilitate visualization since the implants will often be installed very close to the incisive canal. The cut of this nerve does not produce negative consequences regarding the vascularization of the palatal region since there are anastomoses with the vascular coming from the greater palatine foramen. After complete detachment, we recommend the use of a temporary X-shaped suture on the palatal flap to keep the tissues retracted and improve the visualization of the operative field without the need for any manual retractor in position. Then, the osteotomy for leveling the ridge begins, according to the initial planning (height of the residual bone and amount of gingival exposure during the patient smiling without the prosthesis). This leveling can be done with a Maxicut drill or, preferably, an inverted pear drill. The initial drilling begins with the start drill with a palatal approach, making sure that this drilling is perpendicular to the bipupilar line; distal perforations are made in 45o with these initial perforations, placing immediately after the canine buttress region. Next, these initial perforations have been made, checked, and adjusted with the face, the standard drill sequence is performed according to bone consistency and always keeping in mind the importance of a sub-drilling to optimize the stability of the implants. It is better to drill less than too much. Too little, correction is possible if the torque is too high to the risk of generating cracks or even a fracture in the ridge. However, too large drilling ends up being something with no possibility of circumventing, as it is not possible drilling in another location most of the time. If you feel the implant may be partially out of the bone tissue, with possible displacement toward the region of the maxillary sinus, when in doubt, make a small lateral opening in the anterior lateral wall of the maxillary sinus and perform probing to orient yourself where it lies. After the osteotomies are finished, it's time to install the implants. It is best to start the installation of the implants using the handpiece with torque calibration on 30Ncm. Once it locks, you finish the installation with the manual device. If the torque is too high, you can make a counter-torque of a few millimeters and, in sequence, go down the implant, redoing this maneuver successively until the implant is fully inserted into the bone. Then, we install the mini abutments in the anterior region, usually with a height of 2 or 3mm. If you have too much gingival tissue, you should gently remove and reshape it accordingly. The distal mini abutments (multi-unit) are generally 30o 3mm high. Completely remove the positioning rods from the angled mini abutments and use the short prosthetic wrench 1.2mm. If you are unsure of the ideal position of these mini abutments, you can remove the stabilization sutures from the palatal flap and check through the surgical guide (or prosthesis with a palatal opening), which will be the best position with the emergence of the prosthetic screw. From that point on, there is nothing new concerning the prosthetic technique. Installation of the mini abutment cover and suture (preferably, we use 4-0 silk and remove the suture in 7 days). Avoid nylon suture, as compression of the nylon not by the prosthesis can cause discomfort in the postoperative period. After the suture has finished, the mini-abutment cover is removed, and the mini-abutment transfers are installed (or titanium cylinders, if you choose to capture the patient's prosthesis). They are splinted with acrylic resin, and this whole complex is joined to the guide (or prosthesis). We recommend using the short transfer screw to not interfere with the patient's occlusion. Three points of acrylic resin are added for the occlusal registration; the antagonistic teeth are isolated with petroleum jelly, and, after the occlusal registration, the silicone impression material is injected with the aid of an elastomer pistol or syringe. After testing the bar and wax teeth set up, the prosthesis is finished within the aesthetic and functional parameters. The prosthesis is then installed. Note the distal implants came out between the premolars, which is excellent from the biomechanics point of view. On the final radiograph, it is possible to assess the magnitude of the inclination of the distal implants. As we installed the implants at 45o with the anterior implants, these emergencies of the screws of the mini abutments of these posterior implants remain slightly distalized, since the mini abutments are of 30o. It does not bring any negative consequences. On the contrary, it tends to further distalize the emergence of the prosthetic screw, further decreasing the size of the cantilever. A widespread situation in the clinical routine is that we have patients with severe periodontal disease with the indication for multiple extraction and implants. Many clinicians are still a little afraid to make implants in the same act due to the possibility of contamination, but there is evidence that this maneuver is possible, reiterating the need for control in the postoperative period(1). Below, we have a case where the ideal tangential position of the implant in the anterior maxillary sinus was critical to achieving optimal anchorage for the All-on-4 Standard. Immediately, the two maxillary sinuses were opened. The performance of the All-on-4 technique in the mandible also has advantages, especially about the distribution of implants and the reduction of the distal cantilever. The surgical sequence is similar to the upper jaw, but it is essential to visualize the emergence of the mental foramen. Generally, the novice surgeon is a little afraid of detaching this region for fear of damaging the nerve; however, as long as the detachment is done with caution, this is not likely. For the treatment of parasymphysis fractures, it is common to dissect this nerve to place two mini plates. Although there is paresthesia in the postoperative period, the sensitivity returns later. Leveling the residual ridge is also essential in the mandible. Although the possibility of the transition from artificial gingiva to natural gingiva is less critical, the lack of bone reduction can leave little space for the metal infrastructure and teeth set up. It can cause future prosthesis to have a small "flange," which will difficult the possibility of hygiene. After the initial reference perforation, we check and adjust the ideal position of this perforation with the patient's face, and also we can use the All-on-4 guide or just the parallelizing pins. As the distal implants will be tilted 45o with the central implants, the prosthetic emergency may be established just above the region of the mental foramen. This clinical situation is not viable in most of the time if straight implants were used in this region. Besides, with the inclination, we can use longer implants. Despite it, implants larger than 15mm are rarely needed. In most cases, we use 3.75x13mm implants in the central region and 3.75x15mm in the posterior part, but obviously, this depends on each case. Many still question us why not put a 5th implant in the midline. The question I ask is: for what? The answer is: if you lose one of the five implants, you don't lose the prosthesis. Could it be? In the paramedian region, we have the highest corticalization. It is rare to loose implants, but when it does, it is usually one of the distal implants. Thus, this implant needs to be reinstalled anyway, regardless of having that extra implant in the anterior region. Possible problems with the Allon4 technique in the jaw. When you do Allon4 but do not work with a zygomatic implant, you are restricted to the All-on-4 Standard mode. Then I ask you: If you have a loss of the distal implant (a rare but possible situation), how will you fix the case? The first option is to reinstall the lost implant in the same region. However, what if there is no bone to redo this distal implant? There is no way; you do need to install zygomatic implants. To master and be safe with the Allon4 Technique, it is imperative to learn to work with zygomatic implants. The Allon4 philosophy tells us WHAT TO DO in the face of the atrophic jaw: All-on-4 Standard, Hybrid, or Zygoma, but there is no clear methodology on HOW TO DO zygomatic implants. With this in mind, we started working on the ZYGOMA 2.0 concept, an objective method of learning to plan and execute zygomatic implants. REFERENCES 1 Malo, P., Nobre Mde, A., Lopes, A., Ferro, A. & Gravito, I. Immediate loading of implants placed in patients with untreated periodontal disease: a 5-year prospective cohort study. Eur J Oral Implantol 7, 295-304 (2014).https://pubmed.ncbi.nlm.nih.gov/25237673/

Is it possible we have zygoma fracture with zygomatic a implant installation? During the osteotomy for the installation of the zygomatic implant, the surgeon must triangulate his vision taking in account the position of the implant in the region of the alveolar ridge, the relation with noble structures (as the orbital cavity and infraorbital nerve), and the ideal position in the area of the body of zygoma. After the total mucoperiosteal detachment, the bone surface often does not provide us the detailed guidance of where it will be the maximum availability of the bone in the region of the body of zygoma. Not rare, the osteotomy falls immediately into the maxillary sinus, and keeping the drill in this direction, it could follow to the infratemporal fossa, without the zygomatic bone being drilled. Using this feeling and judgment, paying attention to the zygomaticomaxillary bone region's external topography, we can decide to go with "a safer" positioning, doing the osteotomy in a more external area concerning the body of zygoma. It anticipates the exit of the zygomatic implant in the body of zygoma, becoming it identifiable and would prevent the entrance of the implant in the infratemporal fossa. However, this approach can bring some significant problems concerning the external cortical of the zygoma. It could become too thin. I already had cases where this thin cortical cracked; however, the zygomatic implant kept stable, and the immediate load was kept successfully. Nevertheless, I had a case where the worst-case scenario just happened. Let's see the case. The zygomatic implants were planned in the 3D model. Once in the perfect position achieved, the zygomatic implants' size was reduced to the initial drill size. After that, the virtual 3D model is "drilled," and we have the "Virtual Osteotomized Prototype." The perfect position guide where we should put os osteotomies. With that prototype in hand, we can study the whole path of the drill during the osteotomy. In this case, we could understand how the challenge would be this case. The drills were slightly passed through the infratemporal fossa, and, at the same time, a thin outer zygomatic bone cortical was left. Under along the osteotomy view, it is possible to check the zygoma external cortical bone after the "virtual zygomatic implant drilling." There was a complete zygoma external cortical breaking, and the implant anchorage was lost. The bone fragment was totally separate from the zygoma, like a piece of bone graft harvested from the mandibular ramus. Situations like that can happen in any case, even though in cases of the bulk zygomatic bone. Just keep the initial osteotomy too displaced toward the external cortical and use a zygomatic implant much thicker than the osteotomy size. If the zygomatic bone is thin, even though the osteotomy passing throws the central area from the internal and external cortical, the cortical fragility is unavoidable. In such situations, our planning must foresee this condition and adjust our planning to keep the outer cortical the most robust possible, preventing its embrittlement and possible breaking. Guess how I found this out? In this case, the patient of low height and presented a zygomatic bone extremely thin. In the virtual planning, the complexity of the case was noticed, where the installation of 4 zygomatic implants would be necessary (Allon4 Zygoma / Quad Zygoma). Immediately after the end of the osteotomy, I realized the challenge (and the problem) that I was facing to install this implant. I started the installation to identify any sudden increase in the installation torque to prevent compression in the cortical. As the implant was being installed, I made a counterclockwise torque movement for the implant itself to function as if it were a screw male. That way, I could have better control of the insertion torque. When I just left about 5 mm for the implant's total insertion, what I feared most occurs— a complete breaking of external cortical of the body of zygoma and the implant's total run down. The zygomatic implant lost its insertion completely. The bone segment of the zygomatic bone's external cortical bone was wholly detached, like detaching a bone block of the mandibular ramus region. In front of such a challenge, the ask is - what to do? Fix the segment with microplates and screws? Abort the procedure? Although all these options came to my mind, I have opted for another one. Reinstall the implant passing through the infratemporal fossa. With the drilling more internal than the previous one, the drill transfixed the infratemporal fossa. During the drilling in this region, it is normal to notice some degree of facial soft tissue trepidation because the drill is being conducted through the muscle, fascia, and fatty tissue. Such segments of the soft tissues can also adhere to the drill's groove after its removal. After passing for this region, the drill initiates the perforation in a more posterior area of the zygomatic bone, going into the zygomatic arch's direction. Although this approach is suitable in extreme situations, such situations are not perfect conditions. Therefore, there is a substantial reduction in the amount of bone insertion of the zygomatic implant, leading to an expressive loss in the insertion torque value. It is essential to notice that the more posterior the zygomatic implant's head is located, the more significant is the trend towards increasing the bone anchorage. That happens because, in such conditions, the osteotomy will pass through zygoma from anterior to posterior. In my case, the anchorage happened, however, as expected, with a low torque concerning a normal situation. It was one of the rare cases of zygomatic implants in which I chose to bury the implants and wait 3 months. After this period, the implants were reopened, and the prosthesis was finished without any issue. What lesson have I learned? In the case of the thin zygomatic bone, we should always make a plan to maintain as much as possible the integrity of the outer cortical. Even when an optimal thickness of zygomatic bone exists, we can plan to displace the osteotomy toward the internal cortical to keep the outer cortical free of damage. Practically we could accept the following. A positioning equidistant or slightly toward the outer cortical can lead to a cortical breaking of the external one. You can completely lose the zygomatic implant's insertion and must have to make new osteotomy in a possible but not ideal position. However, with a dislocated positioning more for the inner cortical, what will happen in the worse of the hypotheses? The zygomatic implant can pass partially through the infratemporal fossa and return immediately toward the more posterior part of the zygoma body. It will promote an anchorage in 4 cortical, and the high torque will be kept. What is the possibility of you to understand this concept without using virtual planning 3D? Zero. The virtual planning allows you to understand the complexity and individuality of each case. It lets you comprehend the zygoma and the path of the drill along the bone and optimize the surgical perceptions that happen in advance. This concept that you've just learned could take years or until decades of practice to be understood, but it is possible to comprehend it with the virtual planning since your first surgeries. That's the reason I keep saying to my students. Put a lot of effort into planning your zygomatic implant cases. It worth it. You will know accurately where it will be the osteotomy, and you will have a smart prototype in your hands (virtually osteotomized prototype). All these tools and knowledge are fully available to everyone. It is worth investing a little time and devotion that the results certainly will be priceless for the surgeon but mainly for the patients. If you want to learn this kind of approach to zygomatic implant click here to know our training.

I could say that in no zygomatic implant book, you will see someone calling attention to this detail, which in my opinion, is one of the most critical factors for effective and predictable rehabilitation with zygomatic implants. With virtual planning, it is currently possible to specify the zygomatic implant's maximum anchorage area in the zygoma body. From there, place the implant's head in the most favorable position concerning the residual ridge and screw prosthetic emergence. More advanced adjustment is possible about the distance between the osteotomy/implant and the internal and external bone cortical. It can be a crucial factor in implant stabilization. The sizes of the zygomatic implants to be selected in each case do not depend only on each patient's anatomy, but also on the three-dimensional positioning of the implants. BIC (bone-implant contact) varies between patients and varies in the same patient, depending on the planning. It is a basic mistake of those who start with zygomatic implants. They believe that only the zygoma thickness will determine precisely the amount of anchorage of the zygomatic implant, which is a mistake. Some surgeons believe that although the zygomatic implant is long, its biomechanics is like a short implant. The zygomatic implant is around 47mm, but the bone's thickness in the region of the zygoma body is only 5mm. Bullshit! I can say that this is one of the main basic errors in understanding the zygomatic implant and its relationship with the zygoma body. The problem is that many surgeons transmit the knowledge applied to conventional implants also to the zygomatic implant, which is a mistake. Let's imagine the following: you will place an implant in the region of tooth 46. When you evaluated the CT scan of this region, you found that it has 6.5mm high and 5mm wide bone. You choose to install a 5mm high and 3.75mm wide implant. Once this implant is perfectly placed, we will have a 5mm bone insertion. Let's assess the zygoma body CT. In the coronal view, we see that the thickness of the zygomatic bone is about 5mm. The surgeon transfers the same form of reasoning to the zygomatic implant; that is, we will have 5mm of insertion into the bone. However, this premise does not apply to the zygomatic implant! The implant position in the maxilla concerning the zygoma body will be from anterior to posterior; that is, it will transfix the zygoma body, from anterior to posterior, and from bottom to top. This implant-bone insertion will be much larger than the thickness of the zygomatic bone and generate high torques, which allows immediate loading. These nuances will be clearly explained, and we will learn to evaluate this amount of bone insertion even before surgery. (a post about it is coming soon). To supply the range of possibilities involving anatomical and planning issues, zygomatic implants must have several dimensions available. Because of it, companies produce various sizes of implants, and ideally, all must be available at the time of the surgical procedure. As much as there is a possibility of preoperative planning, small changes in the initial angulation culminate in considerable differences in the zygomatic implant's final size needed. The ideal position concerning the implant head about the residual ridge and antagonistic teeth also contributes to selecting the exact size of the implant. Sometimes, we have substantial maxillomandibular discrepancies, which is better managed with the most prolonged zygomatic implants (implant's head as anterior as possible). Among the sizes of zygomatic implants available, there is a wide variation from company to company. When it comes to the smallest zygomatic implants available, we have not found any difference by companies, which are zygomatic implants with a length of 30 to 32mm. However, when it comes to maximum size, things change completely. Whenever we performed Allon4 Zygoma (Quad zygoma) cases, the anterior zygomatic implants generally needed to be very long implants to have a good relationship with the residual ridge. Sometimes, the head of the most anterior zygomatic implants is positioned close to the lateral incisor region. From a surgical point of view, it is essential to note that the further anterior the head of the zygomatic implants in the alveolar ridge region, the more the zygomatic implant will cross the body of the zygoma from anterior to posterior, increasing the zygoma bone anchorage. The opposite decreases bone anchorage. Understand that the more posterior the head of the zygomatic implant in the residual ridge, the more vertical the implant will have to be, and the more perpendicular the implant will transfix the body of the zygoma, decreasing the amount of bone anchorage. Maybe these concepts sound a little abstract to you now, but these concepts are experienced and internalized intuitively in virtual planning. The fact is that to have such cases well-conducted, longer zygomatic implants are essential. When I started using Neodent zygomatic implants, this was an aspect that I promptly realize because, in this zygomatic implant system, the longest implant was 52.5mm, very different from the system I had been using (SIN Implant System), which had the most extended implant of 62.5mm. For this reason, I ended up returning to using the implant system from SIN Implant System. I always believed that these clinical perceptions were not seen or commented on among colleagues who work in zygomatic implants until I came across an interesting scientific paper. The authors made a series of virtual planning of zygomatic implant surgery, placing the implants in the area of maximum bone availability in the zygoma body. The authors' conclusion was exactly what I had already experienced in practice: It is worthy to note that when the apex of the previous implant was placed at Point A3, the average lengths of the implant were 55.68 + - 63.41 mm, which were beyond the lengths of the commercial zygomatic implants. Therefore, to obtain the largest BICs, it is suggested to produce longer zygomatic implants. Another study by Pelegrino (2020) also found a similar conclusion (2). I think that the zygomatic implants' size is a crucial factor to be taken into account when deciding which zygomatic implant system you will use. I have compiled all the information regarding zygomatic implant sizes and other important aspects of the world's main implant companies in this post. I recommend that everyone read the article below. After all, the scientific basis is what drives clinical decisions. It is certainly what companies should prioritize when developing new solutions that meet the clinical needs of surgeons. Short size zygomatic implants The use of excessively short zygomatic implants can be used in two different situations. 1) Planning error Take a look at this paper (3), where a virtual plan was made with the implant's head positioned more posterior region (which I do not recommend). Realize that in situations like this, zygomatic implants always end up having a smaller size. The clinical repercussion of it is the formation of a huge anterior cantilever. 2) patients with a short face In patients of short size and short face, the length of the zygomatic implants is proportionally shorter. I had a case where I used the smallest zygomatic implant that I had available in the system I was using - 32.5mm - and the apex of the implant was beyond the external cortical of the zygoma body. Fortunately, the implant's apex was rounded and, although it was possible to feel the prominence with the skin palpation, the patient did not present any complaints. When a surgical planning and execution error is made, the zygomatic implant is installed with its head in a more posterior position to the ridge in short-faced patients; you could need shorter zygomatic implants than those available in the market. The length of the zygomatic implants is critical information and tells us beforehand if the planning is consistent with our case's anatomical reality. Virtual planning (correctly executed) is fundamental not only for an excellent clinical result but also for the surgeon to understand such nuances to accelerate his learning curve regarding installing zygomatic implants. REFERENCES (1) Hung KF, Ai QY, Fan SC, Wang F, Huang W, Wu YQ. Measurement of the zygomatic region for the optimal placement of quad zygomatic implants. Clin Implant Dent Relat Res. 2017 Oct;19(5):841-848. doi: 10.1111/cid.12524. Epub 2017 Aug 1. PMID: 28766912. https://pubmed.ncbi.nlm.nih.gov/28766912/ (2) Pellegrino G, Grande F, Ferri A, Pisi P, Gandolfi MG, Marchetti C. Three-Dimensional Radiographic Evaluation of the Malar Bone Engagement Available for Ideal Zygomatic Implant Placement. Methods Protoc. 2020; 3 (3): E52. Published 2020 Jul 22. doi: 10.3390 / mps3030052 https://pubmed.ncbi.nlm.nih.gov/32707931/ (3) Duan Y, Chandran R, Cherry D. Influence of Alveolar Bone Defects on the Stress Distribution in Quad Zygomatic Implant-Supported Maxillary Prosthesis. Int J Oral Maxillofac Implants. 2018 May/Jun;33(3):693-700. doi: 10.11607/jomi.4692. PMID: 29763505. https://pubmed.ncbi.nlm.nih.gov/29763505/

What happens if I partially pass the zygomatic implant through the infra-temporal fossa? The violation of the infratemporal fossa during the performance of osteotomies for the zygomatic implant can happen due to two situations: 1) Perforation error 2) Intentionally planned maneuver Given this, some questions are unavoidable: will it bring us any problems? Is there any risk in this maneuver? What are the advantages and disadvantages of positioning the zygomatic implant in such a region? Before answering these questions, let's understand when this situation happens. 1) Perforation error When the surgeon finishes the mucoperiosteal detachment and has the maxillozygomatic region exposed, it is time to define where our perforation's initial position will be. Intuitively, we tend to choose regions where there is a bulky bone, which would probably denote more bone volume. The problem is that such areas do not always represent where maximum zygoma bone availability exists. The region with the bulk external bone topography can "be hollow," that is, after the initial perforation, the drill falls directly into the maxillary sinus. Once inside the maxillary sinus, the drill must continue until it finds the entrance to the zygoma body. It is here where the problems begin. As it is a region without direct visualization, the surgeon can progress with the drill only in the "feeling" and end up drilling the maxillary sinus's posterior wall and entering directly into the infratemporal fossa. In these cases, the lack of bone resistance is evident. When removing the drill, you will notice soft tissue in the drill grooves, instead of bone. When it happens, you need to recognize that your clinical judgment is wrong. As much as the clinical judgment by analyzing the external bone topography of the maxillozygomatic region indicates that the zygomatic implant position should be in that location, the result of the drilling process is telling you with absolute certainty that it is not. You are mistaken. It is not uncommon in zygomatic implant surgery. But then, where should I do the new drilling? At this point, some surgeons decide to take a more invasive approach, trying to understand what is happening more visually. The solution is to open a window in the upper-superior-anterior part of the maxillary sinus to identify where exactly the entrance of the zygoma body is. In this way, the exact point of entry of the drill bit can be inspected, which significantly facilitates identifying the precise location of drilling. For a long time, I have always used this approach as a surgical protocol. In the most challenging cases, I would always open this window to optimize the drill's positioning. But is this ideal? NO! Large maxillary sinus openings contribute to a decrease in the capacity of the sinus mucosa's ciliary motility, contributing to the possible development of sinusitis. It is worth reading this paper (1), which, despite not focusing on zygomatic implants but zygoma fractures, brings great insight concerning our surgical technique and the potential consequences of wide sinus openings. Nowadays, with the possibility of 3D virtual planning, it is clear that the zygomatic implant can be installed with a single precise perforation directly in the optimal region without the need for any sinus opening. Even though some are still reluctant to take this new approach, this is the new era of zygomatic implants!. Precise virtual planning allows us to know precisely where we should do our initial drilling and anticipate all synesthetic perceptions. All of it without doing any anthrostomy. The fact is that when you enter the infratemporal fossa due to perforation errors, depending on the magnitude of the error, the implant can reach more posterior locations of the infratemporal fossa, and this can damage soft tissue structures. However, a partial and more anterior violation of the infratemporal fossa can be intentional, as we will see now. 2) Intentionally planned maneuver When planning the installation of zygomatic implants in cases where the zygoma body has a thin thickness, the position of the implant passing equidistant from the internal and external cortical of the zygoma body can cause the external cortical to become very thin. During the installation of the zygomatic implant, this cortical may crack, but the implant may remain stable, or the worst, which may be a total fracture of the outer cortical of the zygoma body, may happen. I wrote a post explaining more details about it. In such situations, a displacement of the drill further towards the zygoma's internal cortical is not only desirable but also fundamental in some cases. In this way, the implant will anchor in four cortices and maintain the external cortical of the zygoma body extremely robust and free of risk of fracture. What is the chance that you can identify and have that kind of clarity without using virtual planning? Zero. That's why many surgeons try to learn zygomatic implants and give up—lack of clarity and an individualized understanding of each case. But after all, is there a problem with the partial violation of the infra-temporal fossa? To answer this question, we need to understand what is the content of the infratemporal fossa. What we have in this region is the insertion of the temporal muscle and fatty tissue. During the drilling process, you will feel a change in drilling pressure, and, when removing the drill, you will notice that you will have fragments of fascia, fat, and / or muscle in the drill grooves. Some facial soft tissue vibration occurs, and the drill lost its bone cut capacity because of soft tissue attached to the drill's groove. It's advisable the clean it. Below, a case in which I pass implant through in the infratemporal fossa. Even authors (2) even suggest this maneuver to increase the number of cortical affected by the implant, and complications or sequelae of it have not been reported. In our virtual planning, we will also have this degree of detail to place the implants and make this fine adjustment, moving our implant slightly towards the inner cortical of the zygoma to protect the outer cortical and optimize our surgical success. Our planning will always seek maximum bone availability to increase the implant's BIC. Some studies have tomographically evaluated the BIC of zygomatic implants, and the variation is immense, ranging from 4.9mm to 32.9mm (3). Indeed, the individual differences in the amount of bone also interfere with this BIC variation, but we firmly believe that the implants' three-dimensional positioning can be even more relevant. Imagine a 4 mm thick zygoma in which a zygomatic implant was installed with its head in the most anterior position possible in the alveolar ridge, which leads to a perforating the zygoma body from anterior to posterior. In this situation, you can easily get around 15mm of implant-bone insertion. Imagine a bulky 7mm zygoma, but a zygomatic implant was installed with the head far posterior on the alveolar ridge, making it crossing the zygoma almost perpendicularly. In such a position, we would do have a 7mm bone insertion. You can already figure out these findings in the virtual planning, visualizing the tomographic slices along the implant axis. In summary, passing the zygomatic implant through the infratemporal fossa has its purpose and indication in cases of the thin zygomatic bone. However, this must be part of pre-established surgical planning and not the result of an inability to conduct surgeries according to plan. Please, share your thoughts and experiences with us on comments. References (1) Ballon A, Landes CA, Zeilhofer HF, Herzog M, Klein C, Sader R. The importance of the primary reconstruction of the traumatized anterior maxillary sinus wall. J Craniofac Surg. 2008; 19 (2): 505-509. doi: 10.1097 / SCS.0b013e318163f2ea https://pubmed.ncbi.nlm.nih.gov/18362733/ (2) Jensen, OT, Brownd, C. & Blacker, J. Nasofacial prostheses supported by osseointegrated implants. Int J Oral Maxillofac Implants 7 , 203-211 (1992). https://pubmed.ncbi.nlm.nih.gov/1398837/ (3) Balshi, TJ, Wolfinger, GJ, Shuscavage, NJ & Balshi, SF Zygomatic bone-to-implant contact in 77 patients with partially or completely edentulous maxillas. J Oral Maxillofac Surg 70, 2065-2069, doi:10.1016/j.joms.2012.05.016 (2012). https://pubmed.ncbi.nlm.nih.gov/22907109/

When the extra sinus zygomatic implant technique started, many questioned themselves about the potential problems with these exposed implants threads. What has been seen is that these exposed threads do not harm the stability of osseointegration of the zygomatic implants. At first, we can believe that this is just a problem caused by the lack of keratinized mucosa around the zygomatic implants; however, even in cases where a reasonable range of keratinized tissue is achieved, such dehiscence might occur. See the case below, recently operated, where a large amount of keratinized tissue was displaced into the buccal region of the implant and, in just three months, there was already a substantial decrease in the amount of gingiva in the same area, which tends in the long term, evolving to exposed implants threads. According to Medrossian(1), in cases of ZAGA 4, the potential soft tissue dehiscence around the zygomatic implant is not preventable, and, preoperatively, the patient must be aware of this possibility and be instructed to perform adequate hygiene in such situations. Should these clinical situations be considered complications, or are they just a kind and side effect of the extra sinus technique? When such situations are evaluated by professionals who do not deal with the zygomatic implant, these professionals generally are promptly concerned with such conditions and even end up using such findings to criticize the zygomatic implant technique. It is because they apply the same way of thinking as conventional implants for the zygomatic implant. In a conventional implant, if you have a 7mm implant, but on clinical examination, you identify that there is around 2mm of bone exposure, you automatically believe that there is only 5mm of bone insertion. However, this mindset does not apply to zygomatic implants, and you will understand why now. When we have a completely extra sinus zygomatic implant installed, the predominant bone insertion (and osseointegration) will occur in the portion of the final third of it, and the soft tissue will be covering the rest of the implant up to the cervical region. If we have tissue dehiscence with exposure of some cervical threads, this does not compromise the bone insertion of the zygomatic implant. Bone insertion is entirely distant from buccal soft tissue dehiscence. Therefore, we can say that: Threads exposed in a zygomatic implant do not compromise the osseointegration of it. The only disadvantage of these situations is that maintaining hygiene can be difficult, especially in implants with surface treatment. Hence the importance of advising patients to use extra soft brushes and oral irrigators with care. If the patient has complaints about the hygiene capacity or some complication, further intervention might be required. One way to prevent tissue dehiscence in a zygomatic implant is to cover the threads with the buccal fat pad right after the implant installation. According to Guennal and Guioll(2), of the 25 patients in which this procedure was performed, all of them had a total absence of dehiscence during the follow-up period. Thus, it is clear that such conduct is valid, especially in risk situations where there is already a lack of keratinized gingiva and in smoking patients. The tissue trauma due to the frictional movement of the mucosa over the implant threads during chewing and brushing is, in our view, one of the main triggers for the emergence of such dehiscence. A possible solution to be investigated would be to modify the zygomatic implants' cervical design, leaving them more receptive to tissue accommodation. In 2018, we proposed a new implant design, which is called Slim Zygomatic Implant (patent pending). In addition to this concavity that precedes the cervical region of the implant, this implant would be totally smooth, without any surface treatment because, from our point of view, osseointegration is not and has never been a problem when it comes to the zygomatic implant, as we are anchoring the implants in a bone with a large amount of cortical bone. In such situations, we know that the surface treatment does not bring so many advantages. In the cervical region, we could accept that the "new normal" of zygomatic implants fully externalized, in the long term, it would be some degree of buccal soft tissue dehiscence. Assuming that possibility, if we have a zygomatic implant fully optimized for such an occurrence, we would have some benefits. It would be ready to maintain hygiene more easily, both by design and by polishing. It would be a "tissue friendly" zugomatic implant. There is also the possibility that its anatomical design prevents the occurrence of such tissue dehiscence. Such probabilities will only be clarified with scientific investigation. References 1. Bedrossian, E. & Bedrossian, E. A. Prevention and the Management of Complications Using the Zygoma Implant: A Review and Clinical Experiences. Int J Oral Maxillofac Implants 33, e135-e145, doi:10.11607/jomi.6539 (2018). https://pubmed.ncbi.nlm.nih.gov/30231096/ 2. Guennal, P. & Guiol, J. Use of buccal fat pads to prevent vestibular gingival recession of zygomatic implants. J Stomatol Oral Maxillofac Surg 119, 161-163, doi:10.1016/j.jormas.2017.10.017 (2018). https://pubmed.ncbi.nlm.nih.gov/29107123/