Early healing outcomes of re-entry sinus floor elevation after prior complete sinus membrane perforation: a pilot preclinical study in a rabbit sinus model

Purpose: To determine the early healing outcomes of re-entry sinus floor elevation (SFE) after previous complete sinus membrane perforation. Methods: In six rabbits, the sinus membrane of one maxillary sinus was intentionally perforated (≥10 mm), and a collagen matrix was applied. SFE was performed on both sinuses after 8 weeks, establishing 2 groups: SFE after previous complete sinus membrane perforation (group SFE_ComPerf) and SFE with an intact sinus membrane (group SFE). The animals were euthanized 4 weeks after SFE. Micro-computed tomographic (micro-CT), histological, and histomorphometric analyses were performed. Results: On micro-CT, no statistically significant differences were observed in total augmented volume or mineralized tissue volume. Histologically, impaired new bone formation was observed near the sinus membrane in the SFE_ComPerf group. Histomorphometric analysis revealed that the area of newly formed bone was significantly smaller in group SFE_ComPerf than in group SFE (5.8±2.7 mm² vs. 10.5±1.9 mm², P<0.05). Such reduced bone formation in the SFE_ComPerf group was also evident in one region of interest (P<0.05). Conclusions: Complete sinus membrane perforation (>10 mm) may compromise new bone formation in re-entry SFE.