A Modified Zygomatic Implant Placement Technique: A Prospective Study up to 6-year Follow-up

Abstract

PurposeThis study proposed a new modified technique for zygomatic implant placement and evaluated the up-to-6-year survival rate of endosseous zygomatic implants of the technique and its effects in preventing related complications, such as peri-implantitis, sinusitis, and implant failure. Materials and methodsThis study included 28 patients (15 females, 13 males; mean age: 53.4 years) with a severely atrophic edentulous maxilla (class VI maxillary atrophy, according to the Cawood and Howell classification) combined with a flat buccal sinus wall (zygoma anatomy-guided approach class 0 or 1, according to Aparicio) who received zygomatic implants using the modified technique. There are 3 key points regarding this technique: 1) the zygomatic implant was placed toward the buccal wall of the maxillary sinus, resulting in the implant head being near or on the alveolar crest and allowing less bulky prostheses to facilitate oral hygiene and to prevent soft-tissue infection; 2) autogenous bone block graft material was utilized to reinforce the buccal wall and increase the stability of the implant head; and 3) sinus grafting was performed using a mixture of autogenous particulate bone, bone graft material and platelet-rich fibrin, which created maximum bone coverage around the implant head to consolidate along with the implant. All implant surgeries were carried out under general anesthesia. Implant-supported provisional prostheses were delivered immediately, except in 7 cases in which the zygomatic implant did not achieve initial stability (< 35 N/cm). All patients were scheduled for regular follow-ups every 3 months. Definitive prostheses were provided 6 months after the surgery. ResultsOf the 28 patients treated, a total of 82 zygomatic implants were installed, in conjunction with 52 conventional implants. All of the implants exhibited good osseointegration; in particular, bone coverage was observed around the implant head and the entire length of the implant. Two patients presented complications. One patient exhibited a soft-tissue infection with pus discharge after 1 month of wearing the provisional prosthesis. The other patient exhibited implantitis 4 years after implant placement. Both patients showed buccal bone resorption but no oroantral fistulas, and the sinus membrane remained intact, with no sinusitis. Overall, the survival rate of both the zygomatic and standard implants was 100%. The zygomatic-implant-supported prostheses improved both functional and esthetic aspects for the patients. No cases of sinusitis or soft-tissue inflammation were reported. The mean follow-up period was 35.7 months (range, 0-72 months). ConclusionThis study illustrates that zygomatic implant placement with the new modified technique with the implant head on or near the alveolar bone, onlay bone block augmentation, and extended simultaneous sinus grafting is a successful and important treatment option when rehabilitating the atrophic maxilla. This modified technique yields a high long-term success rate and prevents complications such as peri-implantitis, sinusitis, and implant failure.Intraoral and radiographic images illustrating the procedure A, B, Intraoral images before and after six-month implant placement. C, D, E, F, Intraoral images showed the four zygomatic implants were placed toward the buccal wall of the maxillary sinus resulting in the implant heads were near or on the alveolar crest. Autogenous block bone graft was utilized to reinforce the buccal wall and to increase the stability of the implant head, extended sinus graft was performed to create an maximum bone coverage around implant head to consolidate along the implant. G, H, I, J, K, Radiographic study of the secondary phase of implant placement six months later with bar connecting the four zygomatic implants. G, Orthopantomographic view. H, I, J, K, CT slices showed the osseous integration surrounding all four zygomatic implants.