ABSTRACT
The use of phosphates in dental glasses and ceramics for the application as biomaterial is merging. Hdyroxy apatite is characterized by its solubility in the oral fluids. Studying the effect of the dissolution process of hydroxy apatite added to conventional dental porcelain on its mechanical strength was our aim in this work. Five formulations were prepared from Egyptian raw materials and the mechanical strength of each investigated formulation was measured. It is found that addition of bone ash in amounts not exceeding 10 percent raised the tensile strength of the investigated dental porcelain. The rate of dissolution of dental porcelain containing bone ash increases with percentage of bone ash added, as the values of mechanical strength were lowered. The pH of the solution was affected by time of immersion. Calcium ions released from the dissolution of tricalcium phosphate readily react with silicon ions giving calcium silicate which render the solution alkaline