Associations between temporomandibular disorders, pain, jaw and masticatory function in dentofacial deformity...

Patients with dentofacial deformity often present with impaired masticatory function, orofacial pain and temporomandibular disorders (TMD). This study investigates the relationship between TMD, pain, jaw and masticatory function at different stages of orthognathic surgical (OS) treatment.

A total of 120 OS patients were prospectively recruited and grouped as pre-orthodontic (group 1), pre-surgery (group 2), 4-month post-surgery (group 3), 24-month post-surgery (group 4), in addition to 30 controls (group 0). Outcomes were assessed using: Jaw Function Limitation Scale (JFLS), McGill pain questionnaire, DC/TMD instrument, voluntary maximum bite force (MVBF), and masticatory efficiency (ME) using two-coloured chewing gum. Data were analysed using structural equation modelling.

The prevalence of non-painful TMD did not differ between groups (p = .827). However, the prevalence of painful TMD differed between groups (p = .001). Among the painful TMDs, the highest prevalence was observed for masseter myalgia in group 2 (p = .031), and importantly group 4 did not differ from group 0 (p = .948). The MPQ score was significantly higher in group 1 (p = .001) compared to group 0, and the JFLS score was significantly higher in groups 1, 2 and 3 compared to group 0. Notably, MPQ (p = .756) and JFLS (p = .572) scores in group 4 were not different from group 0. However, MVBF (p = .996) and ME (p = .991) did not differ between groups 1 and 4. The association of self-reported pain and jaw function with the masticatory function was observed in OS patients.

OS was not associated with a negative impact on TMD. Jaw function and pain levels were similar to controls at the 24-month follow-up. The masticatory function was further affected by the surgery and seems to require a longer recovery time. Moreover, it was confirmed that pain and TMD were associated with limitations in jaw function and impacts on masticatory function.