Effect of Zn and Mg on the formation of whitlockite in human subgingival calculus.

X-ray diffraction analyses were carried out from pooled samples of old subgingival calculus. Also the concentration of Ca, Mg, Zn, Sr, Pb, Fe and Cu from these samples were determined by means of atomic absorption spectrophotometry. The comparison of the samples containing almost the same Zn concentration and two different concentrations of Mg (9 mg/g and 16 mg/g) showed an increase of 2.0.10 and 220 whitlockite reflections with an increasing Mg concentration. The increase of Mg concentration shifted whitlockite reflections suggesting a contraction of a-axis. The increase of Zn concentration showed an increase of 2.0.10 and 220 reflections indicating the fitness of Zn into the lattice of whitlockite. No changes of a-axis were detectable. When comparing all diffractograms and the results obtained from chemical analyses, the presence of Zn-MG-whitlockite proved evident.