Temporomandibular joint dysfunction, or TMD, is a common injury that affects millions of people everyday. In fact, it is estimated that around 50% of the population may be affected by some type of TMD. TMD is defined as pain or tenderness, often accompanied by symptoms including audible clicking, headaches, earaches, and jaw locking, related to the dysfunction of the temporomandibular joint, or TMJ. There are three major types of TMD which include internal derangement, degenerative, and myofascial varieties. It can affect anyone but it seems to affect women more than men in a 4:1 ratio and its peak incidence occurs between the ages of 20-40. It typically presents as jaw or facial pain that can radiate into the neck, jaw, or temporal areas. Often it can be accompanied by a loss of proper range of motion in the jaw, audible clicking with chewing, and even locking. Some patients also get earaches, headaches, and neck pain with it. There are many common causes of TMD that should be considered in order to remove the causative factors. Hypermobility and hypomobility can be a cause for TMD.
Disc displacement inside the joint can cause snapping and popping as well as jaw locking and pain. Patients that grind their teeth at night can cause asymmetrical wear and tear on their teeth which can result in jaw displacement and abnormal stresses during chewing and biting and can lead to TMD. Muscle spasms in the muscles of mastication (chewing) can lead to abnormal placement and movement of the jaw during chewing. Dental conditions such as poorly fitting dentures, toothaches, and long periods of dental work can cause displacement and pain as well as degenerative osteoarthritis and direct trauma as seen in car accidents, boxers, and facial injuries. There are many different orthopedic and exam findings that help to diagnose the cause of TMD by a chiropractor, physical therapist, or medical doctor. Palpation in the TMJ space will most likely be tender and in late stages will involve crepitis or a crunching sound/feeling. There will be increased pain with clenching or chewing and a measure of range of motion of the jaw will reveal a limited range of motion overall, but specifically on the affected side. The normal range of motion of the jaw is around 40 mm, or 3 fingertips, and is measured upon jaw opening by measuring the space between the upper and lower incisors. The jaw may also open and close incorrectly with the appearance of jaw protrusion or lateral deviation of the mandible. Normally the jaw should depress in a straight motion and should not deviate to either side. This is called mandibular tracking. Palpation of the muscles of mastication including the masseter and pterygoid muscles will reveal tenderness and possibly muscle spasms or trigger points. Diagnostic imaging is sometimes used to determine internal structural stability. Normal x-rays are usually not very helpful in the diagnosis but can be used in cases of trauma to determine a fracture of dislocation. An MRI can be useful to determine the position of the intraarticular disc but is often used as a last resort after traditional noninvasive treatments have failed. Videoarthrography is an expensive and painful form of advanced imaging that can also be used to view the TMJ through the process of clenching and chewing but it is rarely used.
Research has shown that chiropractic treatment of TMJ is very effective and should be considered before invasive procedures are incorporated. Chiropractors work with the muscles and the joint to free fixations and restore the proper biomechanical properties in order to reduce the pain and clicking and retrain the muscles to work properly. It is estimated that 75% of TMD patients will have their symptoms fully resolve within three months under multidisciplinary care including chiropractic, dental, and physical therapy. With proper instruction and treatment, the majority will not experience any further issues in the future. Chiropractors use muscle therapy including trigger point therapy, myofascial release, stretching, massage, and Active Release Technique (ART) to relax and lengthen tight and spasmed muscles and simple exercise to strengthen weak muscles in order to restore balance to the jaw and realign the joints. Sometimes gentle manipulations of the TMJ are incorporated to realign the joint and reduce fixation within the joint. Ultrasound and electric muscle stimulation can be helpful, using a small probe applicator to apply the therapy directly to the muscles of mastication and the TMJ. The patient should avoid hard and chewy foods for a period of time and should refrain from chewing gum or hard candy if that proves to be a cause for concern. Stress reduction is another helpful activity which in turn can reduce teeth grinding. In some cases referral to a dental specialist is required to correct dental damage or to negate grinding of the teeth through the use of a night guard or a splint. In any case, patients that experience TMD for a period longer than 3 weeks should seek a medical evaluation by a dentist, chiropractor, or medical doctor.