Sixteen replamineform hydroxyapatite implants were inserted subperiosteally on the residual ridge in five dogs, and various soft-tissue procedures were performed at intervals of one, two, three, and 27 months after implantation. Three implants served as controls. Twelve of the 13 surgical sites healed normally, including four of the five vestibuloplasties and all eight exposure sites. All 16 implants were still in place and firmly attached to the alveolar bone at the time of sacrifice. A normal stratified squamous epithelium was formed in all specimens in which complete healing occurred. No evidence of an inflammatory reaction was found in response to the soft-tissue surgery in the specimens that healed. The favorable results of this study form the basis for proposed human clinical trials to evaluate the response of the implant and the overlying soft tissues to a dental prosthesis.