Three-Year Prospective Randomized Comparative Assessment of Anterior Maxillary Single Implants with Different Abutment Interfaces

Abstract

The goal of this investigation was to define time-dependent peri-implant tissue changes at implants with different abutment interface designs. Participants requiring replacement of single maxillary anterior and first premolar teeth were recruited and treated under an institutional review board (IRB)-approved protocol. Implants, titanium abutments, and provisional crowns were placed in healed ridges 5 months following preservation after tooth extraction with recombinant human bone morphogenetic protein-2 (rhBMP-2). Twelve weeks later, permanent crowns were placed on patient-specific abutments and evaluated at 6, 12, and 36 months following implant placement. Clinical and radiographic assessments of abutments and crowns, peri-implant mucosa, and marginal bone levels were recorded. The 3-year assessment included 45 conical interface (CI), 34 flat-to-flat interface (FI), and 32 platform-switched interface (PS) implants in 111 participants. At 3 years, the mean marginal bone level (MBL) change at CI, FI, and PS implants was -0.12, -1.02, and -1.04 mm, respectively (P = .014). "Zero" MBL loss or gain was measured over the 3-year period at 72.1% CI, 3.0% FI, and 16.6% PS implants. There was a minor change (0.0 to 0.3 mm) in peri-implant mucosal zenith positions over time and between groups. Eighty percent of CI implants, 61% of FI implants, and 84% of PS implants were observed to have a clinically stable peri-implant mucosal zenith position with less than 0.5 mm of measured recession. Over the 36-month period, there were no significant changes in the location of mesial or distal papilla in any group. Significant differences in MBLs were observed at different implant interfaces. Conical implant interfaces, but not flat-to-flat or platform-switched implant interfaces, were associated with no MBL changes over 3 years. Peri-implant mucosal stability was generally observed. The relationship of marginal bone responses and peri-implant mucosal stability requires further evaluation.