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.

Outcome of orthodontic mini-implant loss in relation to interleukin 6 polymorphisms.

Mini-implants (MIs) are used increasingly for orthodontic anchorage and their success may require some osseointegration, which is affected by the underlying host immune-inflammatory response. Interleukin 6 (IL-6) is a cytokine expressed during the host response after a trauma or infection. The aim of this study was to investigate the association of clinical characteristics and IL6 tag single nucleotide polymorphisms (which capture the information of the whole gene in terms of genetic variability) with the loss of MIs for orthodontic anchorage. A total of 487 patients were treated with orthodontic MIs between 2004 and 2010. After the application of inclusion and exclusion criteria, the sample comprised 104 patients with one or more MIs that had been in function for at least 6 months with no loss, and 31 patients who had lost one or more MIs. Allele A of rs2069843 and allele T of rs2069849 were suggestively associated with the loss of MIs for orthodontic anchorage and were in complete linkage disequilibrium, which means that one of them is sufficient to capture the same information. The location of installation (mandible) and the number of MIs installed per patient were also associated with the loss of MIs.