Changes in bite force and muscle forces in the upper extremities after counter irritation

Today, physical therapy is recognized as an effective, reversible, and conservative treatment for temporomandibular disorders (TMD). The purpose of this investigation is to explore the feasibility of utilizing counter irritation with ischemic pain at a remote site outside of the head and neck region as a method for restoring muscle force in a course of physical therapy. Twenty healthy asymptomatic female subjects were recruited for this study. The experiments were performed over two days, with the two experimental days randomly assigned to the experiment performed with or without counter irritation. The counter irritation was applied to the subject's left hand using a submaximal effort tourniquet procedure. The maximal bite, finger-pinch, and handgrip forces were measured on the right side, and the results from the days with and without the counter irritation were compared. As a result, a significantly higher mean maximal bite force and a trend toward higher finger-pinch force were observed with the irritation than without the irritation, while there was no significant difference in the handgrip force. These findings indicate that counter irritation outside of the head and neck may be useful for increasing bite force, and may be applicable in the treatment of TMD for the restoration of masticatory muscle force.