[Application of modified lateral window for maxillary sinus floor augmentation].

Objective: To evaluate the clinical efficacy of modified lateral window for maxillary sinus floor augmentation (MSFA). Methods: Fifty-five patients who visited the Stomatology Hospital Affiliated to Zhejiang University School of Medicine between June 2012 and October 2014 were enrolled in the study. Patients underwent MSFA with Bio-Oss grafts based on modified access window. During the operation the vertical height of the bony window was reduced from 6-8 mm of conventional oval window to 4-5 mm of slot-shaped window. The sinus membrane was detached completely via the lateral access and large particle Bio-Oss graft was placed in the sub-mucosal space. The implant survival, graft height, graft volume and resorption rates were measured. Intra-op and post-op complications were recorded. Results: There were 86 implants inserted. The 2-4 year cumulative survival rates were 97.67% by implant-based analysis and 96.36% by patient-based analysis. The residual bone height was (4.7±2.6) mm and bone width was (8.4±2.7) mm. The bone height of implantation site immediately after operation was (16.1±2.5) mm and it was (16.2±2.2) mm at restoration. The bone heights at 1 and 2 years after operation were (14.9±2.5) mm and (13.6±2.6) mm, respectively. The graft height was (10.6±2.8) mm and the graft volume was (1569±745) mm3 immediately after operation. The resorption rate of graft height 6 months after operation was 3.79% and that of graft volume was 7.87%. The 1-year accumulative resorption rate of graft height was 6.63% and that of graft volume was 10.89%. The 2-year accumulative resorption rate of graft height was 7.58% and that of graft volume was 15.26%. Small membrane perforation during MSFA was observed in 5 cases and all were successfully repaired by a collagen Bio-Gide membrane. Conclusion: The modified lateral technique obtains high implant survival rate, excellent graft stability and low complication rate at 2-4 year clinical follow-up, indicating that it is a safe, predictable and minimally invasive surgical method for severe atrophic maxillary posterior dentition.