Regulation of enamel and dentin mineralization by vitamin D receptor

Vitamin D plays an important role in bone mineralization. Enamel and dentin are two mineralized tissues of different origins that are part of the tooth structure, but the mechanism by which vitamin D regulates the mineralization of these tissues remains unclear. We examined the mineral deposition pattern of enamel and dentin in continuously erupting incisors in a vitamin D receptor (VDR) deficient mouse model to determine the effect of vitamin D receptor pathway on enamel and dentin mineralization.

VDR wild-type mice (VDR+/+) and VDR-deficient (VDR--/--) littermates were sacrificed at 70.5 days of age, and their mandibles were dissected. Immunostaining of biglycan and decorin was used to evaluate the dentin maturation. Micro-computerized tomography (micro-CT) was used to compare the mineral density (MD) of enamel and dentin of the two groups at different regions along the axis of the mandibular incisors. Scanning electronic microscopy (SEM) was employed to examine the ultrastructure of enamel and dentin at the levels corresponding to those examined in the micro-CT studies. Furthermore, an accelerated eruption procedure was performed to exclude the effect of delayed eruption on enamel and dentin mineralization.

Different mineral deposition patterns of enamel and dentin were observed at different levels of the incisors in the VDR+/+ and VDR--/-- groups. Early enamel maturation and mineralization, and dentin hypomineralization were observed in the VDR--/-- group.

Vitamin D affects enamel and dentin mineralization through different mechanisms. It may affect the mineralization of dentin systemically while enamel mineralization may be regulated locally.