A Multicenter Randomized Comparative Trial of Implants with Different Abutment Interfaces to Replace Anterior Maxillary Single Teeth

Purpose: The implant-abutment interface may affect peri-implant mucosal architecture, and influence health and esthetics. The goal of this 1-year follow-up report of a 5-year clinical investigation was to examine the periimplant mucosal tissue responses to different implant-abutment interface designs. Materials and Methods: Subjects requiring an anterior maxillary implant were recruited. Tooth extractions, with or without preservation or ridge augmentation procedures, were performed as required. After 5 months of healing, one of three different implant-abutment combinations (conical interface [CI] n = 48); flat-to-flat interface [FI] n = 49); or platform switch interface [PS] n = 44) was placed and provisionalized. Twelve weeks later, permanent crowns were placed and data gathered throughout the first year. Peri-implant mucosal architecture and bone levels were evaluated clinically, photographically, and radiographically. Results: At 1 year, seven FI and six PS implants failed and two FI and two PS implant participants were lost to follow-up, resulting in survival rates of 100% (CI), 85.7% (FI), and 86.4% (PS) (90.8% overall). Marginal bone level changes were -0.22 mm (CI, P .05), -1.2 mm (FI, P .05), and -1.32 mm (PS, P .05) after 1 year. Marginal bone level stability (≤ 0.5-mm bone loss or gain) was recorded for 87% (CI), 8% (FI), and 27% (PS) of implants. Measurement of midbuccal mucosal zenith and papilla positions revealed no change in the mucosal positions and 0.2 to 0.3 mm of gain in papilla dimensions in all groups. Conclusion: Significant differences in marginal bone loss were observed among the three implant-abutment interfaces. At 1 year follow-up, changes in the buccal mucosal zenith position or papilla dimensions were not discernable. A continued longitudinal evaluation of peri-implant bone and mucosal changes around these different interfaces is ongoing. Keywords: immediate provisionalization, esthetics, marginal bone levels, peri-implant mucosa