Effects of an occlusal splint on integrated electromyography of masseter muscle in experimental tooth clenching in man.
Six male subjects exercised maximal voluntary tooth clenching until fatigue appeared in the masseter muscle and until pains and exhaustion of this muscle could no longer be endured; that is, the fatigue threshold and the pain tolerance of the muscle were determined in seconds. An occlusal splint was inserted and the clenching exercises were repeated. During these exercises, and also during 10s of clenching, the electrical activity in the masseter muscle was recorded by bipolar surface electrodes and linearly integrated. Use of the splint did not result in significant changes in the subjective sensations of onset of fatigue and endurance of pain. As the periods of clenching increased, after insertion of the splint, the electrical activity decreased consistently, and use of the splint caused a significant decrease in the electrical activity of the pain tolerance test. As induced by the splint, there was no orderly pattern in changes of the fatigue thresholds and pain tolerances in relation to changes in the electrical activities of these parameters. The mode of action of the splint, in reducing the muscle activity, might have been that of stretching the elevator jaw muscles beyond their resting length.
D000328:Adult; D002012:Bruxism / Q000503:physiopathology*; D003766:Dental Occlusion; D004576:Electromyography; D005221:Fatigue / Q000503:physiopathology; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology*; D009119:Muscle Contraction; D010146:Pain / Q000503:physiopathology; D013165:Splints; D013997:Time Factors