Thoracic spine manipulation did not improve maximal mouth opening in participants with temporomandibular dysfunction

Temporomandibular joint disorders (TMD) have a prevalence of more than 5% in the general population. A positive correlation exists between temporomandibular joint mobility and cervical spine mobility. Similarly, a relationship exists between thoracic and cervical spine mobility. However, it is unknown if interventions to improve the mobility of the thoracic spine positively impact temporomandibular joint motion and pain. This study tested the hypothesis that a single thoracic thrust joint manipulation (TJM) would improve maximum mouth opening (MMO) compared with participants without TMD as well as decrease TMD symptoms.

Forty-eight people with TMD (30.9 years old ±11.3) and 55 people without TMD (28.5 years old ±9.2) participated. Both groups received a seated upper thoracic TJM and were measured for MMO before and immediately following the TJM. The duration of TMD symptoms and pre-thrust current pain, using the 11-point Verbal Pain Rating Scale (VPRS), was recorded in the TMD group. Participants in the TMD group were contacted 2-3 days after TJM to report current VPRS and improvement utilizing the Global Rating of Change (GROC) scale.

No difference in MMO treatment response over time was observed between groups (p = .56). The MMO in the TMD group improved from 40 to 41.3 mm, and the non-TMD similarly improved from 44.5 to 45.4 mm. The VPRS decreased from 2.4 (±1.8) to 1.3 (±1.5) following thoracic TJM (p < .001), and the average GROC score was 1.8 (±2.25), which was statistically different than zero (no change; p < .001). The duration of TMD symptoms prior to TJM was not associated with GROC scores (r = .018, p = .90) or VPRS change scores (r = -.07, p = .64).

The observed treatment effects did not exceed previously reported standards for clinical relevance (5 mm and 2 points, respectively).