Immediate function dental implants inserted with less than 30 N·cm of torque in full-arch maxillary rehabilitations using the All-on-4 concept: retrospective study

The aim of this retrospective clinical study was to evaluate the short-term implant success rate and marginal bone loss in full-arch fixed prosthetic maxillary rehabilitations supported by implants in immediate function with the All-on-4 treatment concept placed with insertion torque of <30 N·cm or ≥30 N·cm. This study included 83 patients (69 female, 14 male) with 332 implants placed (120 inserted with <30 N·cm and 212 inserted with ≥30 N·cm) who were treated between January 2010 and March 2013. Outcome measures were implant success and marginal bone loss at 1 year of follow-up. Ten patients (12.0%; 13 implants inserted with <30 N·cm and 27 implants with ≥30 N·cm) were lost to follow-up. The cumulative implant success rate was 97.5% at the patient level, and 98.3% for implants inserted with <30 N·cm and 97.5% for implants inserted with ≥30 N·cm. The mean ± standard deviation marginal bone loss at 1 year was 1.14 ± 0.38 mm for implants inserted with <30 N·cm and 1.39 ± 0.49 mm for implants inserted with ≥30 N·cm (significant difference; P < 0.001, Wilcoxon signed rank test). These results indicate that implants with insertion torques of <30 N·cm may render comparable success rates and marginal bone loss at 1 year compared to implants inserted with insertion torques of ≥30 N·cm.