The effect of fluoride, zinc, strontium, magnesium and iron on the crystal-structural disorder in synthetic carbonated apatites

The purpose of this study was to investigate the effect of trace metals and fluoride on structural disorder in carbonated apatites and to consider the relevance of the results to dental apatite (enamel). Synthetic carbonated apatites were precipitated in the presence of low levels of zinc, magnesium, strontium, iron and fluoride. Crystal imperfection, as indicated by X-ray peak half-widths, was altered markedly by the substituents. Fluoride alone was effective and zinc- fluoride was the most effective combination in compensating for disorder caused by carbonate inclusion. These results show that disorder induced by carbonate inclusion can be modified greatly by appropriate elements. Trace-element inclusions may therefore markedly affect dental enamel reactivity. Carbonate content alone cannot be used as an indicator of the reactivity of apatite or of the potential susceptibility of dental enamel to caries.