Endurance to physical strain in patients with temporomandibular disorders: a case-control study

Abstract

Objective. The hypothesis tested was whether patients with temporomandibular disorders (TMD) have an impaired endurance to motor tasks, under physical strain. Material and methods. The study population included 81 cases with TMD and 75 controls. After giving their informed consent, the participants filled out a questionnaire and performed five endurance trials. Each trial was measured in seconds from start to termination. The tests included: (a) holding the arm in a straight out position with a 2 kg weight in the hand, (b) lifting and lowering the arm with a 2 kg weight in the hand, (c) opening and closing the mandible repeatedly against a resistance of 1.6 kg during the jaw-opening phase, (d) protruding and retracting the mandible repeatedly against a resistance of 1.6 kg during the protruding phase and (e) unilateral chewing of three pieces of chewing gum. Analysis of differences between cases and controls for endurance were evaluated with Mann-Whitney U-test. A p-value < 0.05 was considered statistically significant. Results. The cases had statistically significantly (p < 0.0001) lower endurance time than controls for all tests. Conclusions. Patients with TMD compared to those without signs and symptoms of TMD have an impaired capacity to endure motor tasks that involve physical demand of the jaw muscles and shoulder girdle muscles.