The Association of Oxidative Stress-Related Gene Polymorphisms with Pain-Related Temporomandibular Disorders and Oral Behavioural Habits

Abstract

The frequency of selected polymorphisms, one in each gene coding for proteins with antioxidative properties (CAT, SOD2, GPX1, NQO1) was compared between patients suffering from pain-related temporomandibular disorders (TMDp;n=85) and control subjects (CTR;n=85). According to the Oral Behaviours Checklist score participants were divided into high-frequency parafunction (HFP;n=98) and low-frequency parafunction (LFP;n=72) groups. In addition, we have investigated the association of selected polymorphisms with participants' psychological (anxiety, depression) and psychosomatic (hypervigilance, somatosensory amplification) characteristics. Polymorphisms rs1001179, rs4880, rs1050450, rs689452 were genotyped using the genomic DNA extracted from buccal mucosa swabs and real-time TaqMan genotyping assays. No differences in genotype distribution between TMDp patients and control subjects were found. Still, TMDp patients who were homozygous for minor allele A, related to the GPX1 polymorphism rs1050450 reported significantly more waking-state oral behaviours compared to GA+GG genotype carriers (score: 30 vs. 23, p=0.019). Frequency of genotype AA for rs1050450 polymorphism was higher in HFP compared to LFP participants (14.3% vs. 4.2%, p =0.030). Most important predictors of waking-state oral behaviours were depression, anxiety, AA genotype (rs1050450) and female sex. Explored genetic factors were not found to be significant risk factors for either TMDp or sleep-related oral behaviours. The association of waking-state oral behaviours with selected gene polymorphisms additionally supports previous assumptions that the daytime bruxism is more closely linked to various stress manifestations, which might also be reflected through the variability related to cellular antioxidative activity.