Tapered Submerged Implants in an Augmented Posterior Maxilla After Oroantral Fistula Closure

Dental implantation in the posterior maxilla is challenging due to anatomic proximity to the sinuses, relative bone quality, and pre-existing sinus diseases. An oroantral fistula (OAF) acts as a pathologic pathway of bacteria and can cause sinus infections and complicate dental implant management. Bony augmentation between the sinus floor mucosa and the oral mucosa at the OAF closure site is another critical consideration. The purpose of this study was to elucidate the sequential patient management protocol from surgical closure of OAF and bone grafting to implant installation. The authors also aimed to evaluate the clinical effectiveness of dental implants in the augmented posterior maxilla. A retrospective study was designed for patients receiving the tapered bone-level dental implants in the posterior maxilla after OAF closure performed by a single surgeon at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital, by applying specific inclusion criteria. Implant survival was determined by the presence of a functioning implant in the oral cavity at the time of assessment. In total, 13 implants were installed in 4 OAF patients with different etiologies. The method of OAF closure differed according to OAF cause and size. Three patients underwent concomitant modified endoscopic sinus surgery. Two patients underwent autogenous bone grafting from the ramus and symphysis, and 2 patients received sequential allogeneic onlay bone grafting. Implant survival was not affected by the type of graft material. The implant survival rate was 100%. An implant diameter of 4 mm (92.3%) and an implant length of 7 mm (69.23%) were most common. Careful separate sinus membrane and oral mucosa closure with sequential bone grafting between ensures stable and predictable outcomes for subsequent implantations. The tapered submerged implants, particularly the 7-mm length, can be reliably installed in the augmented posterior maxilla after OAF closure.