Dental calculi attached to human deciduous teeth were investigated by means of decalcified sections, microradiography, scanning electron microscopy, X-ray microanalysis and microhardness tests.
In decalcified sections or microradiograms, calculi were observed on the surfaces of the enamel, cementum and/or the resorption site of dentin. The typical configurations of the structural elements were glubular, lamellar and woven-lamellar and were similar to those of the calculi attached to permannt teeth.
The outer, inner and fractured surfaces of the calculi were observed by means of scanning electron microscopy. On the surfaces, there were calcified bacilli, calcified molds of bacilli and plate like crystals. Hexahedrally based crystals in various sizes were seen on the inner surfaces of the calculi.
X-ray microanalysis revealed that there was a large amount of Ca and P on the surfaces of calculi at various places. At the same sites, small amounts of Zn, S and Cl were frequently detected. The hexahedrally-based crystals contained much Ca, P and a little Mg.
The microhardnss value of the calculus attached to the cervical enamel indicated 144-198 V. H. N.. The V. H. N. are nearly equal to those of calculi on permanent teeth.
Dental calculi were observed in children above 6 years of age. Their surface views showed mainly milky white or greenish white coloring.