TMD is not just a problem, but a group of conditions, often painful, that affect the jaw joint or TMJ and the muscles that control chewing.According to statistics published in the Journal of the American Dental Association in 1990, 44% to 99% of TMJ problems are caused by trauma. This could have been an injury as obvious as a blow to the jaw with a fist or something as subtle as a whiplash injury with direct trauma to the head or jaw.