THE EFFECTS OF TITANIUM AND HYDROXYAPATITE ON OSTEOBLASTIC EXPRESSIONAND PROLIFERATION IN RAT PARIETAL BONE CULTURES

Titanium and hydroxyapatite are used for the fabrication of dental and orthopedic implants. The longevity of these implants depends on the a mount and rate of bone formation that occurs around their surfaces. In the present study, the effects of titanium, hydroxyapatite, and polys tyrene (control) on the proliferation of rat calvarial cells, and on t heir capacity to express alkaline phosphatase and respond to parathyro id hormone (PTH) stimulation, were studied. The nature of the substrat e did not affect the DNA and protein contents of experimental and cont rol cultures throughout the experimental period. Alkaline phosphatase expression and PTH response, as assessed by DNA synthesis and adenylat e cyclase activity, were higher in cultures grown on hydroxyapatite an d polystyrene than in those grown on titanium. These results indicate that hydroxyapatite was a more favorable substrate than titanium for t he growth and differentiation of osteoblast-like cells in vitro.