Polymorphisms of genes encoding P 2 X 7R, IL ‐1 B , OPG and RANK in orthodontic‐induced apical root resorption

Objective Orthodontic‐induced external apical root resorption ( EARR ) is a complex phenotype determined by poorly defined mechanical and patient intrinsic factors. The aim of this work was to construct a multifactorial integrative model, including clinical and genetic susceptibility factors, to analyze the risk of developing this common orthodontic complication. Materials and Methods This retrospective study included 195 orthodontic patients. Using a multiple‐linear regression model, where the dependent variable was the maximum% of root resorption (% EARR max) for each patient, we assessed the contribution of nine clinical variables and four polymorphisms of genes involved in bone and tooth root remodeling (rs1718119 from P2 RX 7 , rs1143634 from IL 1B , rs3102735 from TNFRSF 11B , encoding OPG , and rs1805034 from TNFRSF 11A , encoding RANK ). Results Clinical and genetic variables explained 30% of% EARR max variability. The variables with the most significant unique contribution to the model were: gender ( P  <   0.05), treatment duration ( P  <   0.001), premolar extractions ( P  <   0.01), Hyrax appliance ( P  <   0.001) and GG genotype of rs1718119 from P2 RX 7 gene ( P  <   0.01). Age, overjet, tongue thrust, skeletal class II and the other polymorphisms made minor contributions. Conclusion This study highlights the P2 RX 7 gene as a possible factor of susceptibility to EARR . A more extensive genetic profile may improve this model.