Outcomes of One‐Piece and Two‐Piece Dental Implants After 15–17 Years: Follow‐Up of a Randomized Clinical Trial

OBJECTIVES: To compare the biological, technical, and esthetic outcomes of one-piece and two-piece dental implant systems after 15-17 years in the follow-up of a previously conducted randomized clinical trial. MATERIAL AND METHODS: This study represents the 15-17-year follow-up of a previously conducted randomized clinical trial included 60 patients requiring dental implant therapy. They were randomly assigned to receive either a one-piece (STM) or two-piece (BRA) implant system. Final restoration delivery served as baseline, after which all patients entered a structured maintenance program. Clinical re-evaluations were performed at 1, 5, 10, 12, 15, and 17 years. Biological, technical, radiographic, and esthetic parameters were assessed at each follow-up visit using standardized clinical and radiographic protocols. RESULTS: Thirty-nine patients with 95 implants, all of whom had completed a 15- or 17-year follow-up visit, were included in the final analysis (STM: 22 patients/45 implants; BRA: 17 patients/50 implants), with a mean follow-up of 16.4 ± 1.1 years. The cumulative implant survival rate was 95.0% (STM: 91.8%; BRA: 98.0%). Marginal bone levels at 15-17 years were 0.08 ± 1.15 mm (STM) and 1.53 ± 0.81 mm (BRA). Clinical parameters remained stable in both groups, although BOP was higher in the STM group. Peri-implant mucositis was observed in 49.7% of all implants and peri-implantitis in 13.3%, with higher rates in the STM group. Technical complications occurred in 28 implants (STM: 23; BRA: 5), with the STM group showing a higher complication rate (implant level: 35.4% vs. 5.8%). Esthetic observations included visible crown margins in 62 implants and mucosal shimmering in 54 implants, with no implant fractures reported. CONCLUSIONS: Both implant systems demonstrated favorable long-term outcomes with high survival rates. While the one-piece system showed superior marginal bone preservation, it was associated with a higher rate of technical complications. TRIAL REGISTRATION: ClinicalTrials.gov identifier: KEK-ZH-Nr 2014-0201.