The Physiology of Temporomandibular Joint Dysfunction

Abstract

Temporomandibular joint dysfunction is defined as a noninflammatory disease which has the three major symptoms of temporomandibular joint arthralgia, joint sounds, and abnormalities in mandibular movements. In other words, since this is the name of a set of symptoms and not a disease itself, the origin is not fixed and it has many varieties.
When we historically consider the theories on the origin of temporomandibular joint dysfunction, three main schools appear.
1) The theory of mechanical pressure due to the condyle.
2) The theory of the exacerbation of tension in the muscles of mastication due to occlusal abnormalities.
3) The psychophysiological theory due to stress.
The disease state of temporomandibular joint dysfunction expresses itself as 1) temporomandibular joint arthralgia, and 2) impaired mandibular movements, and although its physiological analyses have been performed, it is difficult at the present stage to give a unified discussion of the origin of the disease since various factors overlap one another creating a vicious cycle.
Concerning the relationship of actions of the mouth closing muscles and irritations in the oral cavity, in particular mechanical irritations to the periodontal membrane and the temporomandibular joint disc, in general sharp stimuli of short duration have an inhibiting effect on the closing muscles while slow, continuous stimuli have an excitatory effect. However, the effect on these muscles varies even with the same stimulus.
Research is presently being carried out into central nervous system activity concerning the question of what types of stimulation at what time exacerbate the activities of the closing muscles.