Static Balance in Participants with Temporomandibular Joint Disc Displacement without Reduction Versus Healthy Participants: A Cross-Sectional Study

Background: There is no consensus on the association between body posture and temporomandibular disorders (TMDs). This study aimed to assess differences in static balance between healthy participants and patients with temporomandibular joint disc displacement without reduction. Material/Methods: Sixteen patients with temporomandibular joint disc displacement without reduction and 14 healthy participants were included. Static balance tests were performed in the rest and "cotton rolls" (participants biting 2 cotton rolls with their upper and lower teeth) mandibular positions. The mean body's center of gravity (COG) sway velocity was tested in each mandibular position on a firm surface with and without eyes open and on a foam surface with and without eyes open. Results: The COG sway velocity did not differ between the TMD and healthy groups regarding mandibular position or testing condition (P>0.05). However, in the control group, the COG sway velocity in the mandibular rest position was significantly higher than that in the "cotton rolls" mandibular position when standing on a foam surface with the eyes closed (P=0.024). In the TMD group, there was no difference in the COG sway velocity between the 2 mandible positions under any condition (P>0.05). Conclusions: This study provides new evidence for static balance alterations in patients with temporomandibular joint disc displacement without reduction. Further studies are needed to investigate postural control changes in patients with arthrogenous TMDs. This study was registered in the Chinese Clinical Trial Registry (no. ChiCTR1800018369).