Stepwise Modified Transcrestal Sinus Floor Elevation in Sites With 3–5‐mm Residual Bone Height: A Retrospective Study

OBJECTIVES: This retrospective study compared the clinical and radiographic outcomes of a stepwise modified transcrestal sinus floor elevation (SM-TSFE) with the lateral sinus floor elevation (LSFE) for simultaneous implant placement in sites with 3-5 mm of residual bone height (RBH). MATERIALS AND METHODS: A total of 149 patients with 3-5-mm RBH underwent simultaneous implant placement using either SM-TSFE (n = 69) or LSFE (n = 80). The follow-up period ranged from 6 months to 8 years. Evaluated clinical outcomes included implant survival rates, sinus membrane perforation, and postoperative complications. Radiographic assessments included preoperative RBH, marginal bone loss (MBL), and vertical bone height changes. RESULTS: Cumulative implant survival rates were comparable between SM-TSFE (91.30%) and LSFE (93.75%) groups (p = 0.537). However, the SM-TSFE group demonstrated a significantly lower sinus membrane perforation rate (7.24%) compared to the LSFE group (18.75%; p = 0.047). Multivariate analysis identified maxillary sinus septa as the strongest risk factor for perforation (p = 0.002). Regarding implant failure, TiUnite surface (p = 0.035) and membrane perforation (p = 0.039) were significant risk factors, while higher marginal bone height (MBH) was identified as a protective factor (p = 0.003). Both groups exhibited comparable MBL at 2 years post-loading (p > 0.05). CONCLUSION: In sites with 3-5 mm of RBH, SM-TSFE provides implant survival rates comparable to LSFE over the observation period but offers a significant safety advantage due to a substantially lower rate of sinus membrane perforation.