Crestal Versus Lateral Window Approaches for Maxillary Sinus Floor Augmentation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background and Objectives: Evidence directly comparing crestal and lateral approaches for maxillary sinus floor augmentation remains uncertain. We compared their outcomes and assessed certainty of evidence. Materials and Methods: Randomized trials directly comparing both approaches were included. MEDLINE/PubMed, Embase, and the Cochrane Library were searched from inception to 30 July 2026, supplemented by non-systematic Google Scholar searches. Risk of bias and evidence certainty were assessed using RoB 2 and GRADE. Outcomes were pooled as risk ratios (RRs), mean differences (MDs), or standardized mean differences (SMDs), with 95% confidence intervals (CIs). The protocol was registered in PROSPERO (CRD420261447905). Results: Thirteen randomized trials (17 reports) were included. No statistically significant differences were found for implant failure (RR 0.50, 95% CI 0.10-2.61), membrane perforation (RR 0.63, 95% CI 0.29-1.38), marginal bone loss at 12 months (MD -0.08 mm, 95% CI -0.31-0.15), vertical bone gain at 12 months (MD -0.81 mm, 95% CI -1.94-0.33) or 6 months (MD -1.07 mm, 95% CI -2.50-0.36), or postoperative pain (SMD -1.56, 95% CI -3.31-0.20). Certainty was low to very low. Conclusions: Current evidence does not establish superiority of either approach. Selection should reflect residual bone height, sinus anatomy, treatment objectives, and operator experience.