Different enamel and dentin mineralization observed in VDR deficient mouse model

Abstract

Vitamin D plays an important role in the bone mineralization process. Enamel and dentin are two mineralized tissues of different origins that combine to form teeth, but the mechanism by which vitamin D regulates these tissues remains unclear. We hypothesized that vitamin D affects enamel and dentin mineralization through different mechanisms. Objective To examine enamel and dentin mineralization in a vitamin D receptor (VDR) deficient mouse model by micro-computerized tomography (micro-CT) and scanning electronic microscopy (SEM). Methods VDR wild type mice (VDR+/+) and VDR deficient (VDR−/−) littermates were sacrificed at 70.5 days old, and their mandibles were dissected. Micro-CT was used to compare mineral density (MD) of enamel and dentin of the two groups at different levels along the axis of mandibular incisors. SEM was employed to examine the ultrastructure of incisors at the levels corresponding to the levels used for the micro-CT studies. Furthermore, an accelerated eruption procedure was performed to exclude the effect of delayed eruption on enamel and dentin mineralization. Results Different distribution patterns of enamel and dentin MD were observed between VDR+/+ and VDR−/− groups. Early enamel maturation, mineralization, and hypomineralization in dentin were observed in the VDR deficient mice. Conclusion Vitamin D may affect the mineralization of dentin systemically, and enamel mineralization may be regulated locally.