Analysis of the association of IL4 polymorphisms with orthodontic mini-implant loss

The aim of this study was to investigate the association of clinical characteristics and IL4 tag single nucleotide polymorphisms (SNPs; rs2227284 and rs2243268) with orthodontic mini-implant (MI) failure. The sample included 135 subjects of both sexes, mean age 48.7±10years (range 20-76years): 104 in the control group (patients without any MI loss) and 31 in the study group (patients presenting ≥1 MI loss). Genotypes were determined by real-time PCR. Bivariate and multivariate analyses were performed (P<0.05). No association was found between the selected tag SNPs and MI loss. The C allele of the IL4 rs2243268 polymorphism in the recessive model was more frequent in patients who had fewer MIs installed (≤2 vs. >2; P=0.043, odds ratio 0.65, 95% confidence interval 0.58-0.74). On multivariate analysis, smoking habit was significantly associated with the group with multiple MIs installed (P=0.036), however the significance of the association with rs2243268 was not maintained. No association was found between the socio-demographic, smoking, or genetic factors studied and MI loss. This study supports the interaction between host and environmental factors and its influence on susceptibility to orthodontic MI failure.