Abstract
The sol–gel method was employed to synthesize hydroxyapatite (HAp) coatings modified with Ag or Zn ions onto Ti‐6Al‐4V substrate. A bacterial strain Streptococcus mutans (S. mutans) and a human gingival fibroblast (HGF‐1) cell line were used to investigate the antimicrobial effect and biocompatibility, respectively. HAp coatings containing 100 ppm Ag^+^ ions suppressed the growth of S. mutans. An apparent inhibition zone around the HAp coating was further observed at Ag^+^ concentration up to 10,000 ppm. However, for coatings containing Zn^2+^ ions, a clear inhibition zone was observed at Zn^2+^ concentration of 10,000 ppm. Nevertheless, the results of HGF‐1 cultivation demonstrated that the Zn^2+^‐modified HAp coatings exhibited better attachment and spread of HGF‐1 than did the Ag^+^‐modified coatings. Zn^2+^ modified HAp coatings also increased the plating efficiency of HGF‐1 cells. The cytotoxicity associated with the addition of Ag and the cell‐conductive capacity associated with the addition of Zn are proportional to the added concentration, from 100 to 10,000 ppm. The dosages of both Ag^+^ and Zn^2+^ ions that should be added to HAp coatings were considered to prevent infection and improve biocompatibility. The results of this study ensure that HAp coatings modified with a moderate amount of Ag/Zn efficiently resist microorganisms and improve biocompatibility. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006