Liñares, AntonioMaceiras Pombo, LucíaNóvoa Garrido, LourdesGonzález, AlejandroRodríguez, BorjaBatalla Vázquez, PilarLeira Feijóo, YagoBlanco Carrión, Juan2025-11-072025-11-072025-07-31Liñares, A., Maceiras, L., Nóvoa, L., González, A., Rodríguez, B., Batalla, P., Leira, Y., & Blanco, J. (2025). Marginal Bone Changes at Bone-Level Implants With Narrow or Standard Diameter Abutments: 1-Year Results of a Randomised Controlled Trial. Clinical Oral Implants Research, 36(10), 1335–1345. 10.1111/clr.700050905-7161https://hdl.handle.net/10347/43621Aim: To evaluate changes in the peri-implant marginal bone level at implants restored with narrow or standard-diameter abut-ments after 12 months. Material & Methods: Twenty-eight partially edentulous patients were randomly allocated to two groups. The test group con-sisted of 14 patients restored with a 2.9 mm diameter abutment (21 implants), while the control group included 14 patients restoredwith a 4.1 mm diameter abutment (17 implants). The primary outcome variable was the radiographic change in the peri-implantmarginal 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 complica-tions, 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 patientlevel, the change in mean radiographic bone level from definitive prosthesis placement to 12 months showed a reduction in thedistance 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, withno statistically significant differences between the groups. No statistically significant differences were observed between the twogroups for any of the secondary outcomes. Conclusions: Considering the limitations of this study, no significant differences in peri-implant marginal bone levels were foundbetween bone-level implants restored with narrow and standard diameter abutments after 12-month follow-up. Additionally, nodifferences were observed in clinical variables, patient-reported outcomes, or complications.engThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in anymedium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.© 2025 The Author(s). Clinical Oral Implants Research published by John Wiley & Sons Ltd.Attribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/AbutmentBone lossImplantsMarginal bone levelsjournal article10.1111/clr.70005open access