Effects of the carbonate content in carbonate apatite on bone replacement.

Carbonate apatite (CO Ap), an inorganic component of human bone, has been clinically applied as an artificial bone substitute. In this study, the effects of the CO content in CO Ap on the replacement by new bone were studied by fabricating CO Ap granules containing 0.9-8.3 wt% of CO . The dissolution rate of CO Ap in a weak acidic solution, mimicking the Howship's lacunae, was rapid for the CO Ap granules containing a larger amount of CO . Histological analyses demonstrated the rapid resorption in CO Ap and replacement by natural bone tissue when the CO content was increased. Therefore, the CO content in CO Ap is a key factor that influences the replacement of the bone tissue.