The Use of Tilted Implants

In his lecture, Prof. Enrico Agliardi will present us the use of tilted implants in different situations. He reminds us that when we treat an edentulous maxilla, we need to consider different atrophies. We can start the rehabilitation of the patient with no atrophy. In these cases, we can place straight implants, but we need to ensure a minimum of 10mm of residual bone under the sinus level in the region of the first molar. The problem starts when the maxilla shows atrophies, then we have to decide in which way we can use the available residual bone. One possible option is All-on-4. All-on-4 was invented by Paulo Malo and described in 2005 for the maxilla and in 2003 in the mandible. Another option is the V-II-V protocol, which Prof. Agliardi described in 2008 and earlier, and which contains two more implants than All-on-4. In his lecture he will show us the details of this protocol. When the atrophy gets more severe, the patient can be treated with the trans-crestal or the trans-sinus approach, a high-skill V-2-V rehabilitation. If the atrophy continues, and there is only basal bone left, the remaining option is a hybrid or double zygoma rehabilitation. Should we have additionally residual bone of 8-10 mm in the incisal region, we can mix the extra-oral and intra-oral implants, a so-called “hybrid” rehabilitation. And finally, when there is no bone at all, only basal bone left, also in the incisal region, the only way to treat the patient will be a double zygoma rehabilitation. 

Prof. Agliardi starts to explain the different treatment options by presenting some clinical cases. The first case is a patient, who complaint about the aesthetic and masticatory function. There are teeth present, so we need to do a backward preliminary planning of the patient, starting with x-ray analysis. We can see the compromised and healthy teeth. Some teeth need to be removed; some teeth can be maintained. In the presented case, the teeth are so compromised so they could not be saved, and he decided to perform a double All-on-4 rehabilitation. He presents us images of the patient in resting position and with a natural smile. It is visible that the patient is compromised with a class anomaly, this case a dental and skeletal class II anomaly which can be correct with the All-on-4 rehabilitation, thanks to the implant placement and prosthesis. The patient shows a deep bite, 2cm between the inferior incisor and the superior one, the incisal edge is in contact with the palatal tissue. For the patient it is difficult to eat, but also to speak in a proper way. The All-on-4 protocol can help to achieve high aesthetic and functional results. He continues to explain the analysis, continuing with the 3D analysis of the face and the smile. This helps to plan the aesthetic restoration and surgery. Prof. Agliardi reminds us that we need a clear understanding of what we want to achieve at the end of the treatment and will help us to avoid mistakes. The first aspect to look at is the vertical dimension, not only the midline, but also the lip support, considering the natural smile and the relationship between the arches. When all is noted, an accurate analysis needs to follow to create an optimal and effective treatment. The lip competence of the patient was a problem, too. Another point to add when planning the prosthetic outcome of the patient before the surgery. The defect of the smile of the patient needs to be detected before the surgery as we need a clear idea of the smile curve. When all is collected, we have a plan how to correct it during the provisional and final stage and we can deliver to the patient an aesthetic and functional restoration at the day of surgery. Prof. Agliardi presents us an image of the final restoration and how all played out due to proper initial planning. He emphasizes to follow the original protocol for All-on-4 as described by Paulo Malo. We see the OPG at the day of surgery and 6 months post-op the final rehabilitation will start. He shares the pre-op and post-op images; 6 months the patient shows stable hard and soft tissues. For the final phases, he uses the facebow including all information from the provisional for the set-up of the teeth. The supra-structure is a CADCAM bar made from titanium (Procera bar) and individual teeth are set up in wax for the try-in. This helps to verify everything, including lip support, occlusion, laterality, and protrusion. When all is confirmed, the restoration is send back to the lab for the acrylic conversion. The final restoration is then delivered to the patient, we can see the occlusal view and the smile of the patient. He concludes the case with showing before and after images, a 3-year follow-up and a 6- year follow-up. The 8-year follow-up shows stable hard and soft tissues, at this time the restoration was renewed to achieve an aesthetic texture of the teeth and the natural smile of the patient. 

Prof. Agliardi continues with a more complex case to illustrate the use of the All-on-4 in a patient with massive atrophy in the mandible. He shares images of the patient extra-orally without prosthesis. In the lateral view the defect becomes obvious as a compromised vertical dimension is visible, as well as abnormal labial nose corners, thin lips, cheilitis and deep commissural folds. Additionally, the patient presents not only a mandibular antero-rotation, but also a hypertone of the chin muscle. The treatment of this patient includes improvement of the vertical dimension, correction of the occlusion, improvement of the profile leading to a postero-rotation of the mandible. The surgery is not easy, as the nerve does not show a bony roof and is inside the tissue, which makes the organization of the flap difficult. The plan foresees the tilting of the two posterior implants. In this case, the tilting helps to improve the length of the implant, in this case a 8.5mm implant with a diameter of 4mm. The anterior implants are 7mm with 4mm of diameter. After the implants, angulated and straight abutments are placed and the lab phase for immediate loading starts. Comparing the existing denture to the plan, it is clear what needs to be adjusted. For the patient, an improvement of the vertical dimension is important, and it needs to be done correctly. The function of the masticatory muscle needs to be controlled and with the rehabilitation the quality of work of the muscle should be improved. Prof. Agliardi checks on this using electromyography. We can see images of the patient immediately after surgery with the provisional restoration, followed by images of pre- and post-op views of the profile. Thanks to the restoration and the correct function, the quality and quantity of the mandible could be improved after 10 months. At 6 months the soft tissue was checked, looking very good and at 10 months the final restoration is delivered to the patient. The patient was very satisfied with the treatment, so she came back after 3 years to have her maxilla treated, too. He shares a 4-year follow-up of the lower restoration and a 1-year follow-up of the mandible. 

Prof. Agliardi continues his lecture with the V-II-V protocol. This protocol includes two more implants than the All-on-4 protocol. The posterior implant of All-on-4 has a disto-mesial inclination, the two posterior implants of the V-2-V protocol, placed distally to the sinus, lead to a mesio-distal inclination. The provisional restoration is placed at the day of surgery. The final restoration will be delivered 6 months after the surgery. He emphasizes that the posterior implant is not a pterygoid implant. A pterygoid implant needs to pass through the maxilla and engage or pass through the pterygoid bone. This is difficult and dangerous, as the procedure can lead to bleeding, difficult to stop. The posterior implant is also not a tuberosity implant, as normally these implants are placed straight and it is difficult to achieve primary stability, needed for immediate loading. Prof. Agliardi places the implant, following the posterior and lateral sinus wall. As the implant is placed close to bone of better quality the stability of the posterior implants will be improved. For the presented case, special implants with a length of 5mm were created. According to Prof. Agliardi, we need to understand when the V-2-V protocol should be used instead of the All-on-4 protocol, i.e. when the opposing jaw has natural teeth or implant supported teeth until the second molar. If such a patient is rehabilitated with All-on-4, we will get a long cantilever. If we have a patient with low density bone in the upper jaw, two additional implants can improve the stability of the rehabilitation. Another reason could be an extensive sinus pneumatization until the canine region. The emergence of the distal implant of an All-on-4 treatment will be in the canine region or between the canine and the first premolar, which also leads to a long cantilever. With two more implants, the cantilever can become negative. Prof. Agliardi shares a case with us, that shows exactly the described scenario: a case with low quality bone. With two more implants, he was able to improve the stability of the restoration. The patient presented herself at the clinic with aesthetic complaints and pain during masticatory function, together with infections all over the maxilla. The protocol was described in 2009, containing immediate loading at the day of surgery (2-3 hours later). 7 days after the surgery, the tissue is healed completely. The process for the final restoration is started 6 months after surgery. As explained before, a facebow is used and all information transferred to an articulator. A wax replica is obtained, helping to improve the aesthetics in the lab. With the digital workflow nowadays, this workflow can even be more simplified. When all is confirmed, the wax-up is duplicated and send for try-in. Aesthetic, occlusion, laterality, protrusion, and lip support are confirmed. The wax-up is send back to the lab for cut-back, the bar is ordered and the individual, ceramic crowns are cemented on in the lab. We see the final restoration in the patient’s mouth and note that everything is covered by the lip. He shares follow-up images of 1 year, 3, 5 and 8 years and besides the patient being older, the aesthetic and function remain the same. 

The next case, Prof. Agliardi shares with us, is a case with only basal bone being present. This is a case for hybrid or double zygoma rehabilitation. As all cases, we start with the thorough analysis of the patient, including the patient in resting position, and during natural smile, analysis of the intra- and extra-oral view as well as OPG and CBCT scans. Also, for these cases we need to have a clear understanding of the result that we want to achieve with the treatment. The start is always the 3D analysis of the face and the smile to best plan the surgery with the best aesthetic and function as possible. The smile line is again an important factor. The presented patient covered her mouth with her hands when smiling, so one aim was for Prof. Agliardi to return the smile to the patient. There is an analysis with teeth, without teeth, with the lips, without the lips. This helps with the visualization of the prosthetic outcome of the patient. The final restoration needs to be exactly as planned for this treatment, event with a compromised patient with maximum atrophy as the presented one. The next step is the surgical phase, with the placement of one implant, a zygoma implant and three more challenging implants as one is in the canine pillar. We see the patient directly after the surgery with the provisional in situ. The patient is already smiling. Also, here the final restoration starts after 6 months. Prof. Agliardi points out the good quality of the soft tissue. He has been performing All-on-4 treatments for 20 years and is placing zygoma implants for 15 years, therefore he knows that it is important to have bone vestibular to the abutment, together with soft tissue. We see images of the patient with stable tissue in the final stage, the smile details, and the lip support. For cases like these, the follow-up is an important part, so he shares images of the 4-year and 7-year follow-up, showing stable hard and soft tissues. This means stable function and stable aesthetics. 

Prof. Agliardi continues his lecture with a case of double zygoma implants. With a more severe bony situation, the achievement of good aesthetic and function is difficult. The patient complains about the masticatory function and aesthetics. The denture is unstable and with a look at the profile, we see a compromised vertical dimension. The analysis of the aesthetic before the surgery is a crucial step, Prof. Agliardi highlights. All these patients show the same signs: abnormal labial nose corners, thin lips, cheilitis, and hypertone of the chin muscle. The function of the masticatory muscle needs to be controlled before the surgery with electromyography, this will be included in the overall analysis. The provisional is created before the surgery with the direct protocol, the surgery with the quad zygoma is done with the extra-sinus protocol. The patient receives the provisional 2 hours after the surgery. The muscle function can be controlled with electromyography, immediately before the final restoration. The occlusion and the work of the masticatory function is correct. The final restoration is delivered 6 months after the surgery. The restoration is made of a titanium CADCAM bar and composite teeth. He concludes the case and his lecture with images 4 years post-op and the restoration showing stable hard tissue and stable function.