Some electromyographic parameters of experimental tooth clenching in children

Twelve children exercised maximal voluntary tooth clenching until pains appeared (pain threshold) in the right masseter muscle and could no longer be endured (pain tolerance). Concomitantly the integrated electrical activity of the muscle was determined as a ratio of the isometric muscle exercises. It is possible that the two exercises were accompanied by progressive muscle fatigue. While changes in the pain threshold could not be related to similar changes in the accompanying electrical muscle activity, the pain tolerance seemed to increase with a decrease in electrical muscle activity. To a large, but unknown, extent the pain threshold might have depended on psychological factors, rather than electrical muscle activity, whereas the pain tolerance to a large, but unknown, extent might have dependend on the electrical muscle activity. The muscle activity of the two subjective tests might have been influenced by the same physiological determinants, e.g. progressive muscle fatigue and ischaemia of the muscle tissue. The number of teeth in contact during the isometric muscle exercises and the size of the gonial angle of the mandible did not influence either the pain threshold and pain tolerance or the muscle activity of these tests.