Painful Temporomandibular Joint Clicking: A Genetic Point of View

Aims: To determine whether there is an association between gene polymorphisms and patients with painful temporomandibular joint (TMJ) clicking when compared to patients with painless TMJ clicking and a healthy control group. Methods: In this pilot study, the genotypic and allelic frequencies of candidate single-nucleotide polymorphisms (SNP) were compared among 60 individuals divided equally into three groups: patients with painful TMJ clicking (n = 20); patients with painless TMJ clicking (n = 20); and healthy controls (n = 20). Participants were genotyped for the following SNPs using real-time polymerase chain reaction: MMP1 –16071G/2G, COMT Val158Met, TNFα –308, IL1β +3954, IL6 –174, and IL10 –1082. The pressure pain threshold (PPT) of the TMJ was also assessed. All variables were compared among groups. Results: Patients with painful TMJ clicking had a significant association and a higher frequency of MMP1 –16071G/2G (P =.042), COMT Val158Met (P =.030), and TNFα –308 (P =.016) when compared to the other groups, as well as a lower frequency of IL10 –1082. Considering PPT values, a progressively lower mean was found in individuals with painful TMJ clicking, followed sequentially by the painless TMJ clicking and the control groups. Conclusion: This pilot study showed that patients with painful TMJ clicking had a significant association with mutant genotypes related to degradation of extracellular matrix components, pain, proinflammation, and anti-inflammation.