Body posture and hand strength of patients with temporomandibular disorder

The aim of this study was to observe the difference between patients of craniocervical muscle pain and nonpatients in head-neck posture, masticatory muscle activity, and the force exerted by the hand. Fifty-one patients and 28 nonpatients were observed. The electric activity of the masseter muscles was recorded when the subjects were doing pinching or grasping with the jaw in positions of rest, clenched, and clenched with gauze. Measurement of right and left tilting or extension and flexion of the head and neck was made from photographs of frontal and lateral views. It was found that the pinching and grasping force was much stronger in men than in women and in nonpatients than in patients with pain. The pinching and grasping force was more powerful with the teeth clenched. Clenching with gauze did not increase, but more often decreased the strength of the hand. The activity of the masseter muscle during clenching was about 10 to 26 times that of the resting activity. The activity decreased slightly when clenching with pinching or grasping. Patients were more likely to have a stretched neck with more extension of the head. Their masseter muscle activity and hand force were significantly weaker than that of the nonpatients.