Ten‐Year Post‐Loading Outcomes of Subcrestally Placed Implants With Internal Conical Connections at 0.5 mm Versus 1.5 mm Depth: A Multicentre Within‐Person Randomised Controlled Trial

Objectives To evaluate whether placing single dental implants either 0.5 or 1.5 mm subcrestally in healed bone crests confers any clinical benefits. Materials and Methods Sixty partially edentulous patients requiring two single implant‐supported crowns were enrolled in a split‐mouth design across six centres. Each site was randomly assigned to receive an implant placed either 0.5 or 1.5 mm subcrestally. Patients were followed up to 10 years post‐loading. Outcome measures included crown and implant failures, complications, aesthetics assessed using the Pink Esthetic Score (PES), peri‐implant marginal bone level changes, and patient preference. Results Eight patients were lost to follow‐up. No statistically significant differences were observed between groups regarding implant failures (7 vs. 3; p = 0.125), patients experiencing complications (10 [18.5%] vs. 7 [13%]; p = 0.508), PES (7.66 ± 3.14 vs. 7.46 ± 2.97, p = 0.510). Ten years post‐loading, patients in the 0.5 mm group exhibited an average marginal bone loss of 0.38 ± 0.84 mm, while those in the 1.5 mm group showed 0.17 ± 0.45 mm, a difference that was not statistically significant (difference = −0.21 mm; 95% CI −0.47 to 0.04; p = 0.097). No patient preference for implant placement depth was noted. No significant differences in outcomes were found between centres. Conclusions Subcrestal implant placement at either 0.5 or 1.5 mm, when at least 1 mm of surrounding bone is present, seems not to affect the long‐term outcomes.