Introduction: The present study aimed to determine the association between single nucleotide polymorphisms (SNPs) in RUNX2, SMAD6, BMP2, and BMP4 genes in relation to tooth-size discrepancy (TSD).
Methods: A cross-sectional study of patients undergoing orthodontic treatment measured the mesiodistal width of permanent teeth from pretreatment dental casts. Sixty-two patients were included in the study and TSD was assessed according to the Bolton analysis. The patients were allocated into a control group (without a TSD), an anterior excess group and an overall excess group. Genomic DNA was extracted from saliva samples, and SNPs previously associated with tooth size were evaluated using a real-time polymerase chain reaction (PCR) system. The Fisher exact test was performed to compare genotype and allele frequencies at an α = 0.05. An Odds Ratio (OR) and 95% Confidence Interval (95% CI) were calculated.
Results: The rs59983488 SNP in the RUNX2 gene was significantly related to the presence of anterior mandibular tooth-size excess in allele (T allele: p<0.001; OR = 11.74; 95% CI =2.61–55.80), and genotype models (GT genotype: p = 0.002; OR = 12.69; 95% CI = 2.47–64.83). The rs3934908 SNP in the SMAD6 gene was significantly associated with the presence of an overall maxillary tooth-size excess in allele (T allele: p < 0.001) and genotype models (TT genotype: p = 0.010).
Conclusion: The present results suggest that SNPs in RUNX2 (rs59983488) and SMAD6 (rs3934908) genes may be associated with the presence of tooth-size excess.
