Objectives: The centric relation (CR) before and after a single physiotherapy session in patients with myalgia and controls without craniomandibular disorders (CMD) was compared using a controlled clinical trial.
Materials and methods: Twenty-two patients diagnosed with myalgia according to the Diagnostic Criteria for Temporomandibular Disorders were included. Five controls showed no symptoms of CMD. All participants were seated on an Orthas chair. The CR was determined with an intraoral process registration (IPR) electronic central bearing device using three methods: a) The adduction point before deprogramming (AP); b) The adduction point after deprogramming by movements on the registration sensor (APD); and c) The manually (hand-)guided centric relation (CRM). Immediately after the first IPR, the participants underwent a physiotherapy session, followed by a second IPR. Cronbach’s α was used as a measurement for internal consistency to evaluate the repeatability of the IPR and the registration methods. The t test was used to analyze the measurable differences between the CR positions of the patients with myalgia and the controls without CMD before and after physiotherapy. Physiotherapy included manual techniques such as massage; stretching; and mobilization of the soft tissue, the temporomandibular joint, and the upper cervical joints.
Results: The internal consistency of all CR methods varied from acceptable for APD (0.65 ≤ α ≤ 0.99) to excellent for AD and CRM (0.79 ≤ α ≤ 0.99). The CR position did not differ significantly in patients before and after physiotherapy (P > 0.05). In controls without CMD, the APD after physiotherapy was significantly more anterior (P = 0.001).
Conclusion: A single physiotherapy session could not change the CR in patients with myalgia.