Prevalence and associated factors of myofascial pain in orthognathic patients with skeletal class II malocclusion

Orthognathic patients with skeletal class II malocclusion frequently suffer from myofascial pain (MP).

Purpose: This study aimed to evaluate the prevalence and associated factors of MP in these patients.

Methods: This cross-sectional study was performed in adult patients with skeletal Class II malocclusion requiring orthognathic surgery. They were divided according to the presence or absence of MP. The predictor variables were craniofacial morphology, sex, temporomandibular disorders, chronic pain, depression, and polymorphisms of dopamine receptors DRD2 (rs6275 and rs6276) and ANKK1 (rs1800497) genes. Data were submitted to statistical analyses using the linear regression model and Poisson regression with a significance level of 0.05.

Results: Sixty-five individuals were selected, of which 50 (76.92%) were females. A total of 21 (32.3%) patients had MP. Individuals with MP showed a decrease in the mandible gonial angle (p = 0.042) and an increased risk of having temporomandibular joint (TMJ) disc displacement (p = 0.003), TMJ pain (p = 0.030), chronic pain (p = 0.001), and severe depression (p = 0.015). Additionally, individuals carrying AA and AG genotypes in rs6275, and CC genotype in rs6276, were more likely to have MP (p < 0.05).

Conclusion: In this study, 32.3% of skeletal class II orthognathic patients had MP, which was associated with a decreased gonial angle, TMJ disc displacement, TMJ pain, chronic pain, depression, and polymorphisms in the DRD2 gene.