Effect of Maxillary Sinus Membrane Perforation on Implant Survival Rate: A Retrospective Study

Purpose: The aim of this retrospective study was to evaluate implant survival rates (ISRs) for implants placed in grafted sinuses where a membrane perforation occurred during augmentation using exclusively anorganic bovine bone (ABB) by means of clinical and radiographic examinations. Histologic information of five biopsy specimens taken from large membrane perforations is also presented. Materials and Methods: Consecutive patients who underwent sinus augmentation procedures at a private practice Dental Institute between 2004 and 2013 were collected from a computer database. The following profiles were selected for data analysis: computed tomography prior to treatment; perforated membrane information according to size: not perforated, small (≤ 5 mm), medium (> 5 and 10 mm), or large (≥ 10 mm); sinuses grafted exclusively with ABB and lateral window covered with a collagen membrane (CM); and implant survival after at least 2 years of functional loading placed in augmented sinuses. Implants were considered survivals in the absence of infection, mobility, or pain. Results: The sample in this retrospective study comprised 531 patients; 214 required bilateral sinus augmentation, and 317 required unilateral sinus augmentation (total = 745 sinuses). A total of 1,588 implants were placed. From 745 augmented sinuses, 237 (31.8%; 523 implants) were perforated during the procedure. Among these, 48 perforations were large (20.2%; 107 implants), 67 (28.3%; 150 implants) were medium, and 122 were small (51.5%; 266 implants). Of 523 implants placed in perforated sinuses, 15 were lost (ISR = 97.1%). Comparison of the ISRs for small (97.7%), medium (97.3%), and large (95.3%) perforations with 1,065 implants placed in nonperforated sinuses (ISR = 97.7%) was not statistically significant. The histomorphometric analysis of the five biopsy specimens showed 24.52% ± 6.99% of new bone, 24.32% ± 6.42% of marrow space, and 51.2% ± 3.75% of the remaining ABB. Conclusion: The difference in ISR for implants placed in perforated and nonperforated sinuses was not statistically significant. Within the limits of the histologic data, histomorphometric results with 24.52% ± 6.99% of new bone formation in sinuses with large perforations showed similar bone formation compatible with nonperforated sinuses described in the literature. The authors attributed the high ISR shown in perforated sinuses in this study to the proper management of the perforations. Keywords: bone substitutes, intraoperative complications, maxillary sinus, osseointegration, sinus floor augmentation, sinus membrane