VDR deficiency affects alveolar bone and cementum apposition in mice

Objective

To compare the mineralisation density (MD), morphology and histology of alveolar bone and cementum amongst VDR +/+, VDR −/−, and VDR −/− groups supplemented with a diet TD 96348, containing 20% lactose, 2.0% calcium and 1.25% phosphorous.

Methods

Four groups of mice (6 mice/group) were identified by genotyping: VDR +/+ mice (VDR wild type), VDR −/− mice (VDR deficient), VDR −/− offsprings derived from VDR −/− parents receiving a supplemental diet (early rescued), and VDR −/− mice fed with a supplemental diet beginning at age one month (late rescued). All mice were sacrificed at age 70.5 days. Micro-CT was used to compare MD and morphology of alveolar bone and cementum. H–E and Toluidine blue staining was used to examine the ultrastructure of the alveolar bone and cementum at matched locations.

Results

In VDR −/− group, alveolar bone and cementum failed to mineralise normally. Early rescue increased MD of alveolar bone in VDR −/− mice with excessive alveolar bone formation, but which not observed in late rescue group. MD and morphology of cementum–dentine complex in both early and late rescue groups were comparable with VDR +/+ group when feeding with high-calcium rescue diet.

Conclusions

VDR affects alveolar bone mineralisation and formation systemically and locally. However, cementum apposition and mineralisation is mainly regulated by calcium concentrations in serum.