Decomposition d'une Bioapatite Phosphocalcique en Milieu Dit Physiologique: Effet de la Sursaturation

Abstract

The effect of saturation of the solution on transformations of a synthetic calcium phosphate was investigated. The solution was shown to have some physicochemical properties equivalent to those of physiological fluid. The Bioapatite is the apatitic octacalcium phosphate (OCPa); it has a low Ca/P atomic ratio identical to that of triclinic octacalcium phosphate (OCPtr). Results of solid analysis coupled with calculations of the degree of saturation of the solution enable us to delimit two saturation domains. In the first domain (low saturation degree), the calcium phosphate evolves only towards an apatitic phase with appreciable improvement of crystallization state. In the second domain (high saturation degree) a monotonous decomposition of the calcium phosphate gives a mixture of an apatitic solide phase and monetite (DCPA). The mechanism of evolution or decomposition process of the OCPa during this in vitro test is discussed.