Temporomandibular disorders (TMD) are a group of musculoskeletal and neuromuscular conditions that involve the temporomandibular joints, the masticatory muscles, and all associated tissues. These disorders are characterized by regional pain and limitation of mandibular range of motion. Pain-related TMD affects approximately 5% to 12% of the population and can affect individual's quality of life. The incidence is about 4 percent. Therapeutic ultrasound is a type of physical therapy that delivers energy via propagation of ultrasonic waves. One gap in knowledge is whether 1 megahertz (MHz) treating frequency has the same efficacy as treating with 3 MHz. This research proposes to test that.

See brief summary.

Inclusion Criteria:

• Adult females
• Bilateral myalgia based on Diagnostic Criteria for TMD (DC-TMD) criteria
• An average pain of 5 or more on a 0 to 10 scale over the last 30 days.

Exclusion Criteria:

• A history or diagnosis of systemic musculoskeletal disorders or rheumatologic diseases (e.g. fibromyalgia, muscular atrophy).
• Certain conditions such as neoplasms or fractures.
• Neuropathies or neurological disorders.
• Currently taking muscle relaxants or analgesics.
• Undergone any form of physical therapy within the last 60 days.
• Severe bruxism requiring mouth-guard treatment.

De-identified data may be shared after analysis completed.

The frequency setting on the ultrasound machine will be set and known only to the principal investigator.