Investigation of genetic polymorphisms associated with severe root resorption in orthodontic surgery patients.

This study aimed to evaluate the association between genetic polymorphisms in the BMP2, BMP4, RUNX2, and SMAD6 genes and the presence of severe external apical root resorption (EARR) in orthodontic patients undergoing orthognathic surgery. EARR represents a significant adverse outcome in orthodontic treatments, and genetic susceptibility may influence its occurrence. A cross-sectional study was conducted with 158 orthodontic patients treated with fixed appliances and mono or bimaxillary orthognathic surgery. Postoperative panoramic radiographs were used to assess severe EARR. Genomic DNA was extracted from buccal epithelial cells. Seven single-nucleotide polymorphisms (SNPs) in the target genes were genotyped using real-time PCR with TaqMan assays. Statistical analyses were performed with Chi-square or Fisher's exact tests. No significant associations were observed for polymorphisms in BMP2 (rs1005464, rs235768), BMP4 (rs17563), RUNX2 (rs59983488, rs1200425), or SMAD6 (rs2119261). However, a significant association was found for SMAD6 rs3934908 (p < 0.05), with the CC genotype more frequent in patients with severe EARR. No deviations from the Hardy-Weinberg equilibrium were observed. The findings suggest that the SMAD6 rs3934908 polymorphism may be associated with an increased susceptibility to severe EARR in orthodontic surgery patients. While most SNPs showed no association, these results contribute to understanding the genetic factors involved in EARR. Further studies with larger samples are needed to confirm these findings and explore gene-environment interactions.