Bone response to dental implants after a 3- to 10-year loading period: a histologic and histomorphometric report of four cases.

The aim of this study was to histologically and histomorphometrically analyze the peri-implant tissue reactions and the bone-titanium interface in loaded Ankylos implants retrieved after loading periods of longer than 1 year. The archives of the Implant Retrieval Center of the Dental School of the University of Chieti- Pescara were searched for Ankylos implants retrieved from humans after a loading period of longer than 1 year. A total of four implants were found: one had been retrieved after 3 years (Friadent plus surface), two after 3.5 years (Friadent plus surface), and one after 10 years (Deep Profile surface). All implants had been loaded; two had been loaded immediately. One implant was retrieved after fracture, one was retrieved after fracture of the superstructure, and the other two were retrieved because of bone resorption with or without infection. Compact bone with few small marrow spaces was present around the three implants retrieved after 3 and 3.5 years; trabecular bone was present around the implant retrieved after 10 years. The bone-implant contact of the three best threads was 35% for the implant retrieved after 10 years, 99% for the implant retrieved after 3 years, and 100% for the implants retrieved after 3.5 years. No untoward effects were present at the interface, and a high bone-implant contact was present around the implants with the microstructured surface. The data show that these implants had the potential to maintain osseointegration under long-term function with continuous and ongoing bone remodeling.