Hydroxyapatite coating on titanium endosseous implants for improved osseointegration: Physical and chemical considerations.

BACKGROUND: For many years, hydroxyapatite (HA) has been used as a bioactive endosseous dental implant coating to improve osseointegration. As such, the coating needs to be of high purity, adequate thickness, crystalline, and of a certain roughness in order to stimulate rapid fixation and form a strong bond between the host bone and the implant. There are a number of ways of preparing the HA coating, resulting in various coating properties. Herein, we report the preparation of the HA coating using a direct electrochemical method without the need for subsequent heat treatment. OBJECTIVES: The aim of this study was to investigate the physicochemical properties of the HP coating, deposited on titanium implants by a modified electrochemical method. MATERIAL AND METHODS: The coating was characterized in terms of surface chemical composition, structure, morphology, coating thickness and roughness. RESULTS: The coating was found to be composed of homogenous HA with Ca/P and Ca/O ratios of 1.62 and 0.35, respectively. No other forms of calcium phosphate were detected. The degree of crystallinity of HA was 92.4%. The surface roughness was moderate (Sa = 1.04 μm) with the coating thickness of 2-3 μm. The scanning electron microscopy (SEM) analysis revealed a uniform, integrated layer of rod-like HA crystals with the longitudinal axes parallel to the implant surface. CONCLUSIONS: The coating reported herein was found to have potentially favorable chemical and physical characteristics fostering osseointegration.