Convex Versus Concave Emergence Profile of Implant‐Supported Crowns in the Aesthetic Zone: 3‐Year Results of a Randomized Controlled Trial

ABSTRACT Aim To evaluate the 3‐year clinical and radiographic outcomes of implant‐supported restorations with different emergence profiles (CONVEX vs. CONCAVE). Materials and Methods A total of 47 patients received a single implant in the aesthetic zone and were allocated to one of three groups: (1) CONVEX: customized provisional with a convex emergence profile ( n = 15); (2) CONCAVE: customized provisional with a concave profile ( n = 16); (3) Control: no provisional restoration ( n = 16). Final crowns in groups CONVEX and CONCAVE were fabricated to replicate the emergence profile of the respective provisional restorations. Follow‐ups were performed at baseline, 6 months, 1 year and 3 years. The primary outcome was mid‐facial mucosal recession and secondary outcomes included clinical, radiographic and aesthetic outcomes as well as profilometric measurements. Multivariable logistic regressions and mixed‐effects models were used to compare the groups. Results Out of the 47 patients originally included, 42 were available for re‐examination at 3 years follow‐up. At 3 years, the frequency of mucosal recession amounted to 46.7% in group CONVEX, 13.3% in group CONCAVE and 40.0% in group Control. Adjusted logistic regression models revealed that the CONVEX group was significantly more likely to show recessions at 3 years (odds ratios ORs: 7.3, 95% CI: 1.02–52.14, p = 0.048) when compared with the CONCAVE group. No statistically significant difference in recession frequency was observed between the CONVEX and CONCAVE groups between the 1‐ and 3‐year follow‐ups (OR: 3.7, 95% CI: 0.30–46.09, p = 0.303). Conclusion The emergence profile design significantly influences soft tissue stability predominantly within the first year after crown insertion. Whenever clinically feasible, a CONCAVE profile is preferable in the aesthetic zone to maintain the level of the mid‐facial mucosal margin and reduce the frequency of recessions. Trial Registration: German Clinical Trials Register: DRKS00009420