Paracrystalline disorder of biological and synthetic carbonate-substituted apatites.

Paracrystalline disorder, a type of lattice imperfection which results in a loss of long-range crystalline order, was assessed in a range of biological and synthetic apatites using x-ray diffraction data. Carbonate substitution in the apatite lattice increased the amount of paracrystalline disorder in synthetic precipitated apatites, whereas trace amounts of fluoride and, to a lesser extent, zinc and strontium partially offset the disorder induced by carbonate. Paracrystalline disorder was significantly reduced in synthetic apatites prepared by high-temperature solid-state reaction. Human dental enamel was less disordered than either dentin or bone.