Kinetics of dissolution of calcium phosphate (Ca-P) bioceramics

Hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) are widely used bioceramics for surgical or dental applications. This paper is dealing with dissolution kinetics of synthetically prepared β-TCP and four types of HAp granules. Two groups of HAp, treated at different temperatures, each of them with two different granule sizes, were tested. Three corrosive solutions with different pH and simulated body fl uid (SBF) were used for immersing of the samples. Changes in concentrations of calcium and phosphate ions, pH level and weight changes of the samples were observed. It was found that presence of TRIS buffer enhanced dissolution rate of the β-TCP approximately two times. When exposed to SBF solution, calcium phosphate (most probably hydroxyapatite) precipitation predominates over β-TCP dissolution. Results from HAp samples dissolution showed some unexpected fi ndings. Neither heat treatment nor HAp particle size made any major differences in dissolution rate of the same mass of each HAp sample.