Early Enamel Maturation observed in VDR Deficient Mice

Vitamin D receptor (VDR) mutation has been reported to be associated with bone loss. In our previous studies, we found that it also results in the abnormal mineralization of enamel and dentin. Furthermore, a high enamel mineralization density in the apical region of VDR deficient mouse incisor was observed. However, it is unclear if this defect is caused by abnormal deposition of mineral element or early enamel maturation. Objective: To observe the effect of VDR deficiency on enamel maturation in an animal model by SEM. Methods: Six wild type mice (vdr +/+) and six VDR deficient (vdr -/-) littermates were sacrificed at 70.5 days of life and the mandibles were prepared for this study. Micro-CT was used to compare the enamel mineralization density at different levels along the axis of the mandibular incisors between the two groups. SEM sections were used to examine the ultrastructure of incisors at the levels corresponding to those used for the micro-CT studies. Results: Based on SEM observations, early enamel maturation was present in the apical region of VDR deficient mouse incisor, where a high enamel mineralization density was observed by Micro CT. Conclusion: Our studies show that high enamel mineralization density in the apical region of VDR deficient mouse incisor is due to the early process of enamel maturation.