The role of genetic in orofacial pain and temporomandibular disorders
BACKGROUND AND AIM: Pain is the most important feature of temporomandibular disorders (TMD) which after the toothache is second cause of orofacial pain. Genetic, hormonal and anatomical factors predispose persons to TMD and factors such as trauma, occlusal changes and parafunction accelerate it. E-search was done in PubMed. English literature from 2000 to 2014 is used. Several studies have shown correlation between DRD2 genes with bruxism. COMT gene carriers with low sensitivity to pain phenotype, apparently 2.3 times less is prone to TMD. Some studies suggest the effect of C Allele of polymorphism rs6313 of gene encoding HTR2A (serotonin receptor) on reducing serotonin connection to receiver of HTR2A in frontal cortex of brain that are risk indicators to bruxism and TMD. According to the most talented women in the risk TMD, the relationship between polymorphisms of the gene encoding estrogen receptor alpha 1 and the risk of TMD was found in women. Furthermore, polymorphisms in the gene for the delta opioid receptor 1 (OPRD1) Glutamate receptor, inotropic, N-methyl D-aspartate 2A (GRIN2A) is involved in creating the TMD. Multifactorial nature of TMD and bruxism shows that a large number of loci interact with each other, apart from the anatomical and hormonal factors play a significant role in the incidence of this complication.