You may hear from time to time someone say “I’ve got TMJ.” TMJ is neither a disease, nor a disorder. The disorder they are often referring to is “TMJ Dysfunction,” or “TMD.”
TMJ stands for “temporo-mandibular joint.” It is the joint that controls the opening and closing of your mouth; with the temporal bone being above your ear, and the mandible: commonly referred to as the lower jaw. Where they come together is the temporo-mandibular joint.
TMJ Dysfunction (TMD) can range from simple tooth and muscle pain to more advanced problems involving the misalignment and degeneration of the temporo-mandibular joint. When you have pain or noise in your TMJ, something is out of place and your joint is not working properly. Healthy joints are pain-free and do not make any noise.
Joint noise can be a popping, clicking or grating noise, depending on the stage of dysfunction. The noises indicate that the pad between the bones is either out of place (popping and clicking) or completely gone (grating noise) and the patient is now bone on bone.
Causes, symptoms, and the progression of TMD
Clenching and grinding: problems without pain
Although there can be several causes contributing to TMD, one of the most common is Clenching and Grinding your Teeth (Bruxism) The medical term for grinding is bruxism. Some people have no pain following a night of bruxing and are completely unaware that they have developed this habit. Bruxers are usually told by a partner who has been awakened by an especially loud and intense episode.
The signs of wear are seen on molars that have become flat, shortened front teeth, and front that appear flat, chipped, thin, or indented. Your dentist can see the wear on your teeth, as the signs of bruxism are quite vivid to the experienced clinician.
While grinding occurs predominately during sleep, clenching can occur while sleeping or while awake. Your dentist may recommend a simple “nightguard” as the appliance of choice to prevent any further “wear and tear” to your teeth. A simple OTC nightguard is not recommended when there is pain or noise in your TMJ as a result of the bruxing habit.
Clenching and grinding: the onset of pain
The most common problem involving pain is myofacial pain or masticatory muscle disorder. Myofacial pain is pain in the muscles of the face. When simple Clenching or Grinding becomes a chronic problem and pain develops, patients may complain of “TMJ.” When questioned where they are experiencing the pain, they may put their hands on their cheeks and/or describe difficulty in opening and closing the mouth. This area is the masseter muscle (found on the side of the face from the cheekbone to the edge of the lower jaw), and it is one of the muscles of closure.
Neuromuscular headaches, often misdiagnosed as migraines, can also be a symptom of clenching. When questioned where they experience the pain of their headaches, patients’ hands often go directly to their temples, or the temporalis muscle, another muscle of closure.
A knowledgeable doctor of dentistry may recommend an appliance called a “flat-planed, canine-guided splint.” This type of nightguard allows the muscles to relax, prevents them from contracting fully, and protects the teeth. These appliances usually require a period of adjusting as the muscles relax over time.
What may compound the problem of TMD are teeth that come together inappropriately. The biting surfaces of teeth are a series of hills and valleys termed cusps and fossae. The cusps have slopes, or inclines, from the cusp tip down into the valley, or fossa. If your teeth come together and a cusp tip hits on a slope or incline rather than in the fossa as you squeeze your teeth together, your teeth slide down these slopes in an effort to chew food. Biting on these slopes is called an interference; interferences can cause the muscles that operate the TMJ to fire antagonistically.
Initially, a splint may be worn for an extended period of time to allow the muscles of the joint to relax, allowing the joint to go into the proper position. This splint is constructed specifically for your mouth by a knowledgeable dentist with advanced training in TMD. This is usually followed by an adjustment of the teeth, with the goal of removing all interferences. An over-the-counter nightguard is an inappropriate device for the treatment of TMD.
If your teeth are coming together improperly, an occlusal adjustment (an adjustment to the biting surfaces of the teeth) may be required to eliminate any inappropriate movement of the mandible triggering the muscle pain. Reshaping of the enamel surface (usually less than 1 mm) may be performed, allowing the bite to stop in a fossa rather than on an incline.
In rare cases, a crown may be necessary to accomplish the proper positioning of the tooth, thereby removing the interferences. Braces (Orthodontics) can also provide the desired rearranging of the cusps and fossae.
Ongoing joint disease and degeneration
Other causes of TMD other than clenching, grinding, or interferences may include trauma to the face, fracture, dislocation, muscle inflammation, muscle spasm, arthritis, infection, and/or growth disorders. TMD itself can lead to a number of dental problems, including joint noise, joint pain, tooth pain, tooth fracture, tooth death, bone loss, bone hypertrophy, space development/tooth movement, tooth sensitivity, limited opening, receding gums, and more.
To summarize, this dysfunction can cause damage to teeth and surrounding structures, pain in the muscles of the face or can go well into five stages of breakdown, with Stage 5 demonstrating complete degeneration of the joint.
Pain in the TMJ is directly in front of or just inside and in front of the ear. Progressive TMD is a multifaceted disorder that can be debilitating and should only be treated by someone with advanced training in its evaluation, diagnosis, and treatment and/or a team of medical, dental, and psychology professionals.
The Mouth/Body Connection
If pain is experienced when chewing, it is not difficult to imagine how one would avoid diet of healthy, crunchy vegetables and nuts to softer, less nutritious foods. Over time, a poor diet can contribute to a number of illnesses, including diabetes and cancer. It is not difficult to see the relationship between diet and a healthy mouth.