Crystallisation of calcium phosphates under constant conditions with a double diffusion set-up

The crystallisation of calcium phosphate (apatite) was studied under computer-controlled conditions using a double diffusion set-up: constant pH in both compartments and constant concentrations of calcium, phosphate and fluoride. The influence of fluoride concentration, pH, overall concentration and of additives (cholesterol, magnesium) on the crystal morphology was investigated. The crystallite shapes fell into two main categories: spheres and hexagonal prisms, depending on the supersaturation. This set-up provides a suitable way to simulate biological crystallisation processes in vitro.