Comparison of implant stability and peri-implant bone changes following simultaneous lateral sinus floor elevation: A prospective randomized clinical study

Objective: To compare implant stability and peri‑implant bone changes between two bone-level implant systems placed simultaneously with lateral sinus floor elevation (LSFE) in the posterior maxilla. Materials and methods: Sixty patients requiring LSFE with simultaneous implant placement were enrolled in this prospective, randomized clinical study. A total of 92 implants were placed: a predominantly cylindrical implant with a mild apical taper (test group, n = 48) and a parallel-walled cylindrical implant (control group, n = 44). Implant stability quotient (ISQ) values were recorded at placement (T1) and after 6 months of healing (T2). Cone-beam computed tomography was used to assess endo-sinus bone gain (ESBG), marginal bone loss (MBL), and three-dimensional bone-volume (BV) changes. Generalized estimating equations were applied to adjust for clustering of multiple implants within individual patients. Results: All implants healed without complications, yielding a 100% survival rate. The test implant showed higher primary stability than the control implant at T1 (70.48 ± 8.02 vs. 55.04 ± 12.47, p < 0.001). Both groups demonstrated increased ISQ values over 6 months, with a modest but statistically significant difference at T2 (80.83 ± 3.43 vs. 78.98 ± 4.18, p = 0.038). No significant differences were observed between groups in ESBG, MBL, BV, or BV resorption rate at any time point. Conclusions: Within the limitations of this short-term study, both implant systems showed favorable early outcomes following simultaneous lateral sinus floor elevation. The implant system with a mild apical taper showed higher primary and secondary stability in posterior maxillary sites with limited residual bone height. Clinical significance statement: In sites undergoing simultaneous LSFE, implants featuring a mildly tapered apex deliver greater primary stability, whereas early secondary stability and peri‑implant bone remodeling are comparable between the two groups. These results confirm that both implant systems achieve predictable short-term outcomes in posterior maxillary sites with limited bone volume. Clinical trial registration: Clinical Trials.Gov, ChiCTR2100042169 © 2026