Degradation of hydroxylapatite, fluorapatite, and fluorhydroxyapatite coatings of dental implants in dogs

Calcium phosphate coatings on dental implants enhance integration of the ma terial. Resorption of the ceramic coatings has raised some concern about th e behavior of the bone-implant interfaces after the coating disappearance. Substitution of the OH- ions by fluoride in the hydroxylapatite (HA) lattic e makes the calcium phosphate more stable. We investigated the degradation rate of dental implants with 50- and 100-mu m coatings of HA, fluorapatite (FA), or fluorhydroxylapatite (FHA), The implants were inserted in dog jaws and retrieved for histological analysis after 3, 6, and 12 months. The thi ckness of the calcium phosphate coatings was evaluated using an image analy sis device. A relative resorption index and its standard deviation were stu died. HA and FA coatings (even at 100-mu m thickness) were almost totally d egraded within the implantation period. In contrast, the FHA coatings did n ot show significant degradation during the same period. The standard deviat ion showed that the resorption process for FHA with thicknesses of 50 or 10 0 mu m was the same, Such a difference was not observed between the 50- and 100-mu m thick coatings of FA and HA. In conclusion, the FHA coatings show ed good integration in the bone tissue and lasted much longer than classic calcium phosphate coatings, (C) 1999 John Wiley & Sons, Inc.