Mechanics of Temporomandibular Joint Dysfunction


The lower jaw may be over closed (too close to the upper jaw), and/or distally displaced (too far back in the joint or socket). Also, the lower jaw may deviate to one side due to interfering tooth cusps (points on the chewing surfaces of teeth that do not meet properly with the opposing teeth).

The cause is multifaceted, i.e., loss of teeth, poor alignment or natural wear of teeth, grinding or clenching of the teeth day and night, poor tongue position, a muscle imbalance in the tongue and the facial muscles, chronic mouth breathing, osteoarthritis, rheumatoid arthritis, trauma, etc.

To determine if an improper relationship exists between upper arch and the lower jaw, it is necessary to relax the muscles of mastication (chewing muscles), then close the relaxed lower jaw on a trajectory that is not strained. In other words, the mouth closes where the muscles are most comfortable. To relax the muscles of mastication, a gentle pulsating stimulus (TENS) is applied to the skin for approximately one hours. Multi-channel electromyography (EMG) is used to verify the degree of muscular relaxation.

Temporomandibular Joint Dysfunction (TMD) is not a rare condition. Every patient has some degree of TMD. It is when symptoms are manifested that people seek help. Many patients tend to clench and/or grind their teeth in response to unconscious stress, creating muscular dysfunction. This usually occurs during sleep, but it may also occur during a stressful daily experience. Resolution of unconscious stress which cause symptoms indicated on a screening questionnaire may require stress counseling. Subconscious stress must be controlled for successful resolution of clenching and/or grinding of teeth.




Posture has an effect on the relationship of the lower jaw to the cranium and can result in a malocclusion (improper bite). If body symmetry is not within normal limits, physical therapy may be necessary to correct body symmetry during treatment.


An airway obstruction must be cleared as it will result in constant mouth breathing. Allergy is a primary cause of chronic mouth breathing. If nasal obstruction is evident, consultation with an Allergist and/or Otolaryngologist will be recommended during treatment. All chronic mouth breathers develop an improper bite (malocclusion).


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