The first group of Axis I, Group I disorders refers to pain in the jaw musculature that may be accompanied by limited range of motion of the mandible. These muscle disorders are based on the presence of persistent pain, usually characterized as a background ache either at rest or during function. Pain is often diffuse and located in the masseter, temporal, and pterygoid muscles. Normal range of motion is 40mm in the vertical plane and can be increased by passively stretching the mandible.
For the muscle disorders , limited motion is defined unassisted opening of less than 40mm and assisted opening of at least 5mm more than the unassisted opening. Muscle pain as a result of myofascial pain is most often bilateral, occurs most frequently in the masseter muscles, and is aggravated by routine jaw use , such as when talking or chewing. The pain is present on a constant and daily basis , and…
