Implant Failure Rate in Transcrestal and Lateral Window Sinus Augmentations: A Descriptive Retrospective Cohort Study

Objectives: This study aimed to describe implant survival rates and associated risk factors in patients treated with two sinus augmentation techniques-Lateral Window (LW) and Transcrestal (TC)-at a single center. Methods: A retrospective cohort analysis was performed using medical records of patients who underwent maxillary sinus augmentation and subsequent dental implant placement between 2015 and 2019 at the Rambam Healthcare Center. Data on demographic variables, surgical approach, graft materials, implant characteristics, and clinical outcomes were collected from electronic medical records. Results: A total of 135 patients met the inclusion criteria, contributing 144 TC procedures (with 144 implants) and 46 LW procedures (90 implants) to the final analysis. The overall implant failure rate was 7.7%, with a significantly higher failure rate for TC (11.11%) compared to LW (2.22%). Procedure type was a significant predictor of implant survival (OR 1.62); however, as residual bone height (RBH) data were unavailable, confounding by indication cannot be excluded and this finding should be interpreted with caution. Implant length demonstrated a significant influence on outcomes (OR 1.28 per mm increase); shorter implants (8 mm) exhibited lower survival rates (81.3%) compared to 10 mm implants (92.3%). Smoking status was identified as a negative predictor of implant survival (OR 0.23). Schneiderian membrane ruptures occurred in nine cases, seven of which were LW procedures. Smoking was the only factor affecting graft survival (OR 0.29). Conclusions: In this retrospective cohort, implant survival rates were higher in the LW group than in the TC group; however, given that individual residual bone height data were unavailable and case assignment, although governed by standardized departmental criteria, was not randomized, the possibility of confounding by indication cannot be excluded. Smoking and shorter implants were significant risk factors for implant failure. Smoking was also associated with graft failure.