An electromyographic and cephalometric study on facial pains and facial morphology in children.

Abstract

Twelve children, five girls and seven boys with a mean age of 12 years, exercised maximal voluntary tooth clenching until intolerable pains and total subjective exhaustion of at least the right masseter muscle forced the children to stop the isometric muscle exercise; that is, the pain tolerance, or the isometric endurance time, of at least the right masseter muscle was determined in seconds, and it amounted to an average of 100 s. Concomitantly, the electrical activity in the right masseter muscle was recorded by bipolar surface electrodes and integrated, and it showed a significant decrease of 32% during the endurance test, probably as an expression of progressive physiological muscle fatigue. A large ANB angle was associated with relatively little decline of the contractile activity and a trend not to endure pains, possibly because isometric tension was generated predominantly by muscle fibres with a high anaerobic capacity.