Myogenous TMD is more common. In its pure form, it lacks apparent destructive changes of the TMJ on radiograph and can be caused by multiple etiologies, such as bruxism and daytime jaw clenching. The cause of the symptomatology (ie, pain, tenderness, and spasm of the mastication muscles) is muscular hyperactivity and dysfunction due to malocclusion of variable degree and duration. Psychological factors may also play a role. In TMD of articular origin, disk displacement is the most common cause.
An important development may connect some of the psychosocial aspects of the disease to underlying neurobiology. This is the discovery that the likelihood of a patient being diagnosed with TMD is related to genetic variations in the gene coding for catecholamine-O-methyltransferase (COMT), a gene related to some aspects of pain sensitivity.
For more on the background of TMD, read here.
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Cite this: Amy Kao. Fast Five Quiz: Test Yourself on Temporomandibular Disorder - Medscape - Mar 01, 2017.