7-mm-Diamater Versus 5-mm-Diameter Immediate Post-Extraction Implants in the Molar Region: 1-Year Results from a Multicenter Randomized Controlled Trial

Introduction and aims: This multicenter randomized controlled trial compared the clinical effectiveness of 7.0-mm wide-diameter implants with 5.0-mm conventional-diameter implants placed immediately after molar extraction. Methods: Thirty-nine patients needing a single immediate post-extraction implant in a molar site were recruited at five centers. Patients were randomly assigned to receive either a 7.0-mm implant (n = 19) or a 5.0-mm implant (n = 20). Any gaps between bone and implant were grafted with a bone substitute. Definitive zirconia crowns were delivered 4 months after implant placement. Outcomes were assessed 1 year after loading and included implant failures, complications, patient satisfaction, changes in peri-implant marginal bone level (MBL), and pink esthetic score (PES). Results: No patient dropped out. No implant failed in the 7-mm group, whereas one implant failed in the 5-mm group (difference = 5.0%; 95% CI: -4.6% to 14.6%; P = 1.000). Four complications occurred in four patients in the 7-mm group versus zero in the 5-mm group, with the difference being statistically significant (difference = 21.1%; 95% CI: 2.7% to 39.4%; P = 0.047). At loading, mean PES was 5.84 ± 2.34 in the 7-mm group and 6.06 ± 4.04 in the 5-mm group, with no significant difference between groups (mean difference = 0.21; 95% CI: -2.03 to 2.45; P = 0.847). At 1 year, the mean PES score was 9.16 ± 2.22 in the 7-mm group and 9.21 ± 2.88 in the 5-mm group (mean difference = 0.05; 95% CI: -1.64 to 1.75; P = 0.950). Mean peri-implant marginal bone loss was 0.83 ± 1.56 mm and 0.45 ± 1.19 mm, respectively (mean difference = 0.39 mm; 95% CI: -0.53 to 1.30; P = 0.396). Conclusion: Preliminary 1-year data showed similar implant survival, esthetic outcomes, and marginal bone loss between 7-mm and 5-mm diameter implants. However, a higher number of minor complications was observed in the 7-mm group. Given the small sample size, larger randomized clinical trials are needed to confirm these findings.