Methods: Buccolingual ground sections, which were spread across the cusp point, of the human deciduous teeth were prepared and observed with polarized microscopy. After being etched with HCl, they were observed from the outer layer to the inner layer of the reparative and primary dentins under the scanning electron microscope/SEM. The contents of seven elements (mass %) were analyzed quantitatively using standard samples with an electron probe microanalyzer/EPMA. Measurements were performed at 10 locations in the outer, middle and inner layers of the reparative and primary dentins in the deciduous teeth.
Results: The reparative dentin was observed brighter than the primary dentin, and the dentinal tubules of them were sparse and slender in polarized microscope. The mineralization front of the reparative dentin at the pulp horn was ridges-shaped and porous and the openings of the dentinal tubules were slender and elliptical. The contents of calcium, phosphorus and magnesium of the reparative middle dentin were significantly lower than the primary middle dentin and those in the deciduous incisor were significantly lower than those in the deciduous molar. It is thought that the reparative dentin is lower calcified than the primary dentin and that the reparative dentin of the deciduous incisor is lower calcified than that of the deciduous molar, judging from the contents of calcium and phosphorus. It is considered that the histological structure of the reparative dentin by attrition indicates the return to the immature, mantle dentin stage of the odontoblasts.
Conclusions: The difference was recognized in the histological structure and elemental composition among human deciduous reparative dentins by attrition.