Epithelial attachment and downgrowth on dental implant abutments--a comprehensive review

The soft tissues around dental implants are enlarged compared with the gingiva because of the longer junctional epithelium and the hemidesmosonal attachments are fewer, suggestive of a poorer quality attachment. Inflammatory infiltrates caused by bacterial colonization of the implant-abutment interface are thought to be one of the factors causing epithelial downgrowth and subsequent peri-implant bone loss. Gold alloys and dental ceramics as well as the contamination of the implant surface with amino alcohols, appear to promote epithelial downgrowth. Physical manipulaton of the abutment surfaces, including concave abutment designs, platform switching, and microgrooved surfaces are believed to inhibit epithelial downgrowth and minimizes bone loss at the implant shoulder. This paper reviews the factors that are believed to influence the migration of epithelial attachment the dental implant and abutment surfaces. Exploration of innovative computer-aided design/computer-aided manufacturing-based concepts such as "one abutment-one time" and their effect on epithelial downgrowth are discussed.

Based on the review of current literature, the authors recommend inserting definitive abutments at the time of surgical uncovering. To implement this concept, registration of the implant position should to be taken at the time of surgical implant placement.