The objective of this research was to compare the response of bony and soft tissues to three dental implants that are currently used experimentally in human clinical dentistry with that of a biologically active ceramic composite developed at Iowa State University. The three commercial dental implant materials were single-crystal sapphire (Bioceram°ler), pyrolytic carbon (Pyrolite°ler), and a titanium alloy (Core-Vent[superscript] TM). The fourth implant material, that was developed at Iowa State University, was a biologically active ceramic composite consisting of tricalcium phosphate and magnesium aluminate spinel;Ten of each of these implants were inserted into the mandibles of dogs and evaluated clinically and histologically for 18 months. The clinical performance was evaluated using rating scales to assess the gingival health, plaque accumulation, gingival sulcus depth, implant mobility, and radiolucency. The histological response of the bony and soft tissue was evaluated using optical microscopic techniques;A gradual increase in tissue reaction with time was observed adjacent to the sapphire implant. Direct bony contact to this implant increased to a moderate amount by 12 months (59%) after which it fell to a low amount (24%). The pyrolytic carbon implant proved to be unsuitable because it was not retained. The combined influences of initial mobility and inflammation caused 90% of these implants to be lost in six months. The titanium alloy implant was associated with a moderate amount of inflammation early in the study. Bony contact increased to a relatively high amount at 12 months (83%). The osteoceramic implant was generally not associated with inflammation. A high amount of bony contact, approximately 80%, developed by three months; nine months earlier than the maximum bony contact observed for the other three implants. This high amount of bony contact was maintained throughout the remainder of the study. Based on this study, the tissue response of the osteoceramic implant was found to be superior to that of the three commercial implants studied.