Characterization of Composite Hydroxylapatite (HA) Coatings for Medical and Dental Devices

Abstract

Porous metallic/bioceramic composite coatings, produced by plasma arc deposition incorporating highly crystalline hydroxylapatite (HA) in a porous structure of titanium or cobalt-chromium-molybdenum, have been developed for medical and dental device applications. An otherwise brittle and weak HA coating has been anchored by a porous metallic underlayer which is strongly bonded to the substrate. Implants with such coatings have the advantage of mechanical fixation by bony ingrowth into the porous metallic structure coupled with enhanced biocompatibility achieved through the use of HA. This combination produces a more stable bone/implant interfacial region as compared to that achieved by a HA coating applied directly on the implant surface. Once bony ingrowth has taken place, strong bonding has been achieved even if bone resorption of the HA were to take place. Various thicknesses, densities and pore sizes of such composite coatings have been applied to dental and orthopedic devices and have been implanted in the U.S.A., Japan, and Europe showing excellent post insertion clinical results. Physical, mechanical, and chemical properties of selected coatings have been characterized and are reported herein.