Fluoridated apatite coatings on titanium obtained by electron-beam deposition

In this report, a series of fluoridated apatite coatings were obtained by the electron-beam deposition method. The fluoridation of the apatite was aimed to improve the stability of the coating and elicit the fluorine effect, which is useful in the dental restoration area. Apatites fluoridated at different levels were used as initial evaporants for the coatings. The as-deposited coatings were amorphous, but after heat treatment at 500 °C for 1 h, the coatings crystallized well to an apatite phase without forming any cracks. The adhesion strengths of the as-deposited coatings were about 40 MPa. After heat treatment at 500 °C, the strengths of the pure HA and FA coatings decreased to about 20 MPa, however, the partially fluoridated coatings maintained their initial strength. The dissolution rate of the fluoridated coatings was lower than that of the pure HA coating, and the rate was the lowest in the coatings with 25% and 50% fluorine substitutions. The osteoblast-like cells responded to the coatings in a similar manner to the dissolution behavior. The cells on the fluoridated coatings showed a lower (p<0.05) proliferation level compared to those on the pure HA coating. The alkaline phosphatase activity of the cells was slightly lower than that on the pure HA coating, but this difference was not statistically significant.