Marginal Bone Changes at Bone-Level Implants With Narrow or Standard Diameter Abutments: 1-Year Results of a Randomised Controlled Trial

Abstract

Aim: To evaluate changes in the peri-implant marginal bone level at implants restored with narrow or standard-diameter abutments after 12 months. Material & Methods: Twenty-eight partially edentulous patients were randomly allocated to two groups. The test group consisted of 14 patients restored with a 2.9 mm diameter abutment (21 implants), while the control group included 14 patients restored with a 4.1 mm diameter abutment (17 implants). The primary outcome variable was the radiographic change in the peri-implant marginal bone level at 12 months, measured as the distance from the implant shoulder to the first bone-to-implant contact (fBIC). Secondary outcome variables included clinical peri-implant parameters, the papilla index, biological and mechanical complications, patient-reported outcomes (PROs) and professional aesthetic assessment. Results: A per-protocol analysis was conducted on the 22 patients who completed all scheduled follow-up visits. At the patient level, the change in mean radiographic bone level from definitive prosthesis placement to 12 months showed a reduction in the distance from the implant shoulder to the fBIC of 0.16 ± 0.31 mm in the test group and 0.21 ± 0.34 mm in the control group, with no statistically significant differences between the groups. No statistically significant differences were observed between the two groups for any of the secondary outcomes. Conclusions: Considering the limitations of this study, no significant differences in peri-implant marginal bone levels were found between bone-level implants restored with narrow and standard diameter abutments after 12-month follow-up. Additionally, no differences were observed in clinical variables, patient-reported outcomes, or complications.