Normalisation of calcium status reverses the phenotype in dentin, but not in enamel of VDR-deficient mice.
OBJECTIVE
To determine the effects of vitamin D receptor (VDR) deficiency on mouse dentin and enamel mineralisation, and how normalisation of serum calcium level affects dentin and enamel phenotypes in VDR knockout mice.


METHODS
Groups of VDR wild-type (VDR+/+), VDR deficient (VDR-/-) and VDR-/- rescued mice were sacrificed at 70.5 days of life. The rescued group was established by a high-calcium diet feeding the VDR-/- mice from postnatal 19 days. Micro-CT was used to compare enamel and dentin mineralisation density (MD) at different levels of mandibular incisors among the groups. The scanning electron microscope (SEM) was used to examine the ultrastructure of the enamel and dentin in the corresponding levels and of surface enamel after acidic treatment.


RESULTS
Micro-CT showed that in VDR-/- rescued group, dentin phenotype was reversed and dentin MD was reversed to normal; however, enamel mineralisation was not reversible, and remained as hypermineralisation in molar region and apical region of the incisors. SEM also revealed enamel hypermineralisation in the VDR-/- rescued group. This early enamel hypermineralisation was more susceptible to acidic erosion.


CONCLUSIONS
Vitamin D affects dentin mineralisation systemically, and it regulates enamel mineralisation locally.
Department of Prosthodontics, University of Alabama at Birmingham, 35294-2170, USA. zhangxm@uab.edu
Xueming
X
Zhang
Firoz
F
Rahemtulla
Ping
P
Zhang
Xingsheng
X
Li
Preston
P
Beck
Huw F
HF
Thomas
D000818:Animals; D050071:Bone Density Conservation Agents / Q000097:blood / Q000494:pharmacology; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary / Q000494:pharmacology*; D003743:Dental Enamel / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003804:Dentin / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D018345:Mice, Knockout; D010641:Phenotype; D018167:Receptors, Calcitriol / Q000172:deficiency*; D014074:Tooth Calcification / Q000187:drug effects / Q000502:physiology*; D014807:Vitamin D / Q000502:physiology*; D055114:X-Ray Microtomography
D050071:Bone Density Conservation Agents; D002136:Calcium, Dietary; D018167:Receptors, Calcitriol; D014807:Vitamin D; D002118:Calcium