Does Apico-Coronal Implant Position Influence Peri-Implant Marginal Bone Loss? A 36-Month Follow-Up Randomized Clinical Trial

Abstract

Preserving peri-implant bone and reducing exposure of the rough implant surface might influence long-term outcomes of implant therapy. The aim of this study was to compare peri-implant clinical and radiologic parameters after crestal and subcrestal dental implant placement at 36months' follow-up. We carried out a randomized clinical trial involving partially edentulous patients in need of an implant-supported, partial fixed dental prosthesis or a single crown. Patients were randomized according to the implant insertion depth: implants placed approximately 2mm below the bone crest (test group) or implants placed at bone crest level (control group). They were evaluated 6, 12, 24, and 36months after prosthetic loading. Peri-implant marginal bone loss was the primary outcome, and the following secondary outcomes were registered: coronal bone changes, plaque index, probing depth, modified bleeding index, retraction and width of the peri-implant mucosa, and peri-implant health condition. Implant survival and success rates after 36months' follow-up were calculated. The study comprised 128 patients (83 men and 45 women; mean age, 54.4±12.2years) and a total of 265 implants (133 in control group and 132 in test group). No statistically significant differences in the peri-implant clinical parameters were found. After 3years' follow-up, 53.4% of the crestal implants and 25.8% of the subcrestal implants presented marginal bone loss, with a mean exposed rough surface of -0.2±0.3mm and -0.09±0.1mm, respectively (P=.001). The overall success rate was 99.6%. Crestal and subcrestal implants showed similar clinical outcomes 3years after prosthetic loading. Significant differences were observed in the radiologic parameters, showing less peri-implant marginal bone loss with subcrestal implants.