Treatment Factors and VDR Polymorphism Effect on Orthodontic Root Resorption

Objectives: The vitamin D receptor (VDR) is involved in a wide spectrum of functions involving mineral metabolism. The association of VDR DNA polymorphisms with external apical root resorption (EARR) concurrent with orthodontic tooth movement has recently been reported. This sex and age matched Case-Control study will investigate the association of a VDR genetic variation and selected treatment factors with EARR concurrent with orthodontia.
Methods: 134 unrelated Caucasians were selected for this study from a larger data bank sample (~1450 participants). All subjects mean age (16.2 years) elected to be orthodontically treated and consented to participate in research. Pre and post treatment diagnostic panoramic, cephalometric, and occlusal radiographs were obtained. 67 subjects were identified to have moderate to severe EARR (only maxillary incisors were evaluated by three independent evaluators). Each of the affected subjects (38 females and 29 males) was sex and age matched with a control.
The following parameters were evaluated for all subjects: 1) treatment duration, 2) extraction of maxillary premolars, 3) numerous cephalometric measurements, and 4) a DNA polymorphism (rs2248098) within the VDR gene (more SNPs within the VDR will be tested in the future). Stepwise logistic regression was utilized to detect associated factors with EARR occurrence with significance at p<0.05.
Results: Treatment duration and extraction of maxillary premolars were significant factors affecting EARR (p=.0001, and p=.0079 respectively), while the VDR SNP was not.
Conclusions: EARR occurrence is associated with extraction treatment and treatment duration, resulting in a greater likelihood of EARR. Further investigation of the contribution of VDR variation is required.