Design features that may influence bacterial plaque retention: a retrospective analysis of failed implants

The purpose of this study was to conduct a postmortem examination of retrieved failed dental implants to identify design characteristics that may have contributed to premature loss.

Forty-five failed implants retrieved from 40 patients with no significant risk factors for implant failure (e.g., history of smoking or diabetes) were examined by scanning electron microscopy. All implants were placed by general dentists or periodontists in private practice and had functioned for an average of 4 years.

Several design features of currently used implants present plaque-retentive areas. Plaque accumulation occurred along the implant-transmucosal abutment interfaces, transmucosal abutment-prosthesis interfaces, implant-prosthesis interfaces, and on surfaces of the abutment, the implant, and the prosthesis. The size of the microgap between the various components, the degree of surface roughness of the restorations and abutments, the exposure of plasma-sprayed coatings and threaded surfaces of implants, and overcontouring of implant restorations contributed to plaque accumulation and provided an ideal environment for bacterial colonization.

These implant features may be key precipitating or exacerbating factors in the development of peri-implant inflammation, predisposing patients to implant failure.