Effect of Some Physico-Chemical Properties of Matrix on Lengthwise and Oriented Growth of Octacalcium Phosphate Crystal

Abstract

Relationship between some physicochemical properties of matrix, such as viscosity, density or structure of the framework, and crystal growth of octacalcium phosphate (OCP) was studied using various concentrations of polyacrylamide gels at 37°C and at pH6.5. Reaction was carried out in a model system of enamel formation, where calcium solution (30 mM) and phosphate solution (5 mM) were separated by a cation selective membrane with polyacrylamide gel on the PO₄ side. OCP grew in ribbon-like morphology in 5–20% polyacrylamide gels. Crystal size of OCP decreased with an increase in gel concentration. In 30% gel, growth of OCP was disturbed. In 7.5% polyacrylamide gel, 1% albumin reduced the crystal size of OCP. In contrast, 1% enamel proteins did not much reduce the crystal size of OCP and OCP crystallized in its characteristic ribbon-like morphology.

Key Words:

• Octacalcium phosphate
• apatite
• tooth enamel
• Ca influx
• enamel proteins