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

Objective: The purpose of this study was to conduct a postmortem examinatio n of retrieved failed dental implants to identify design characteristics th at may have contributed to premature loss. Method and materials: Forty-five failed implants retrieved from 40 patients with no significant risk factor s for implant failure (eg, 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. Results: Several design features of currently used implants presen t plaque-retentive areas. Plaque accumulation occurred along the implant-tr ansmucosal abutment interfaces, transmucosal abutment-prosthesis interfaces , implant-prosthesis interfaces, and on surfaces of the abutment, the impla nt, and the prosthesis. The size of the microgap between the Various compon ents, the degree of surface roughness of the restorations and abutments, th e exposure of plasma-sprayed coatings and threaded surfaces of implants, an d overcontouring of implant restorations contributed to plaque accumulation and provided an ideal environment for bacterial colonization. Conclusion: These implant features may be key precipitating or exacerbating factors in the development of peri-implant inflammation, predisposing patients to impl ant failure.