Immediate Loading on Tapered Versus Straight Multiple Implants: A 3-Year Follow-Up of a Randomized Clinical Trial

Abstract

Objective To evaluate the clinical and radiographic outcomes at 3 years following immediate loading of tapered implants (TI) versus straight implants (SI) from a randomized controlled trial (RCT).Materials and Methods Of the 41 patients who received 93 implants in the original RCT (TI group: 23 patients, 50 implants; SI group: 18 patients, 43 implants), those who completed 3-year follow-up were included in this analysis. Implant survival and success rates, as well as changes in marginal bone loss (MBL), were assessed and compared using Kaplan-Meier curves, Cox proportional hazards models, and linear mixed-effects models.Results A total of 28 patients with 61 implants were evaluated (TI group: 15 patients, 32 implants; SI group: 13 patients, 29 implants). At 3 years post-immediate loading, cumulative survival rates at the patient level were 95.8% for the TI group and 78.3% for the SI group (intergroup p = 0.109). At the implant level, survival rates were 96.2% for TI and 90.0% for SI (intergroup p = 0.351). All implant failures occurred within the first year (1 implant in TI; 5 implants in SI), and no further losses were recorded thereafter. However, two TI implants in a single patient exhibited progressive peri-implantitis during follow-up. Mean MBL values were 0.61 +/- 1.70 mm for the TI group and 0.53 +/- 0.53 mm for the SI group, with no statistically significant differences between groups (intergroup p = 0.428).Conclusion It could be cautiously concluded that the TI rather than the SI might be a more predictable option in terms of achieving an optimized initial stability for immediate loading in the posterior region. Once osseointegration was successfully achieved, however, the macro-design of the implant might not have an influence on the clinical and radiographic outcomes including the osseointegrated state during the 3 years of observational period.