TMD stands for temporomandibular joint disease (commonly referred-to as "TMJ") and it is a term that covers a large number of disorders but the main three categories are Internal joint derangement, Degenerative disc disease and myofacial pain.
Common causes of TMD include, traumatic injury, clenching and grinding, and arthritis of the joint. Traumatic injury includes any force to the face or jaw or even internal tissues within the mouth. Common causes include sports injuries, and motor vehicle accidents. Traumatic injury resulting in fracture of the mandible can lead to eventual TMJ dysfunction.
The cause of clenching and grinding is still being widely studied and not entirely understood. There is evidence that clenching and grinding at night relates to airway resistance in different sleeping positions. The patient's natural anatomy of tonsils, adenoids, tongue and cheek tissue in any way obstruct or cause resistance to clear respiration. When these patients undergo sleep studies that monitor clenching and grinding it is found that times of airway resistance lead to increased jaw repositioning to create a more open airway.
A large known source of clenching/grinding and subsequent facial pain is emotional stress. Individuals with a history of clenching and grinding will notice a significant increase in symptoms through times of emotional stress. Bracing and clenching the jaw during the day is involved as well.
Some individuals seem to be more prone to grinding especially at night. Most of sleep grinding occurs in non-REM light sleep. The early and lightest part of the sleep cycle. With 4-6 cycles a night and these cycles lasting up to 65 minutes per cycle thats roughly 4-6 hours of grinding during a given night. Substances that affect our sleep cycles such as caffeine, alcohol, smoking all negatively affect the sleep cycle. Caffeine has been shown to prolong the lighter stages of
Sleep, shortening of the deep sleep stages and lead to more frequent awakenings throughout the night. Alcohol allows people to fall asleep quickly but with greater sleep disruptions throughout the night and increased cycling through lighter sleep stages. This makes grinding worse because a person who drank alcohol before bed experiences much more time in the light sleep stages than a person who didn’t drink alcohol before bed. Tobacco use can lead to multiple arousals throughout the night and spend more time in the light stages of sleep as well. Reducing or eliminating these substances will lead to a more balanced sleep and a decrease in teeth grinding for those affected.
Patients with arthritis have an increased incidence of TMJ when the joint becomes affected by the systemic inflammation.
Up to 85% of TMD disorders are muscle related in some way. Myofascial pain syndrome is known for muscle pain, radiating pain, tight taught painful muscles sometimes with limited function or movement of the TMJ. Patients can experience pain in the face, jaw joint area neck or shoulders including the ear. This pain can occur during the day, and often times can get worse at the end of the day after a day of eating and speaking. Patients may experience pain in the temples while sleeping, in the morning accompanied by sore teeth. Some patients feel fatigued at the end of the day and want to limit the use of their jaw to avoid talking and chewing. Recurring headaches that are localized to the temples and side of the head.
When a patient who has been experiencing painful symptoms and range of motion limitations presents to the dental office a comprehensive evaluation of the temporomandibular joint complex is performed. First your dentist will perform a dental exam to ensure that the symptoms aren’t due to tooth related causes such as tooth decay, infection or recent dental work. The dentist evaluates how big the patient can open without pain and also evaluate how big the patient can open even with pain. They are looking for limitations to motion that are either due to pain or a physical resistance. They will evaluate any jaw movement side to side or deviation during opening or closing or movement to the side without moving back to the center (known as deflection). They will palpate the joint in motion to determine if there is any grinding activity, painful clicking or popping. Since muscles are the main cause of many symptoms of TMD the dentist will palpate your chewing muscles to determine any pain on palpation or significant firmness of muscle which would indicate prolonged co-contraction and build up of fibrous tissue.
Once the dentist has identified that the TMD is related mostly to muscle pain they will begin conservative therapy. First if the patient came to the office in extreme pain (much more than their baseline) and appear to be experiencing an acute episode of TMD they will instruct the patient to begin a two week course of NSAIDs, frequent warm compresses (warm moist heat) applied to affected areas (temples side of face) for a period of two weeks and a texture soft diet. Limiting any function in the painful range is key to getting through a TMD flare-up. Avoiding overly chewy foods like dried fruits or caramels or overly crunchy foods like raw vegetables and pretzels. If inflammation is suspected a course of steroids might be prescribed or a two week course of muscle relaxers. The muscular pain in TMD has not been shown to be due to over-activity of the muscles through studies however muscle relaxers do allow the system of muscles to relax and the patient to sleep which can help the patient through their acute period and provide some relief. It is important for the patient to have a custom occlusal splint made as soon as possible to prevent frequent recurrence of pain.
Occlusal splints are designed to discourage clenching and grinding during the night and allow the muscles to adopt a more relaxed position. Many patients have success with a decrease in headaches around the temples and other TMD symptoms with wearing a custom splint every night. Occlusal splints are fabricated to cover the biting surface of the teeth covering the whole upper arch. They are made of a hard acrylic and have balanced contact with the lower teeth to avoid muscles tensing on one side to compensate. If these therapies provide significant relief but the patient still has consistent symptoms of pain or headaches around the temples, treatment with BOTOX can be discussed.
BOTOX treatment for TMD can significantly reduce painful symptoms in patients. Botox can be injected into the chewing muscles to decrease the strength of contraction. The dose administered is not high enough to cause muscle paralysis or loss of function. The muscles will still work but they won’t be over-contracting during use and contracting during rest. These muscles involved are in a near constant state of contraction therefore their intensity of contraction is too strong and leading to pain and muscle stiffness. With time and continued treatment every 3-4 months the muscle will lose its stiffness and ability to over-contract. Using the BOTOX to limit the strength of contraction over time will cause shrinking of those muscle fibers and inability of that same muscle to contract as hard. With regular treatment the hope is that as the muscle becomes “weaker” less frequent botox will be needed. It is important that the patient is also wearing their occlusal splint every night as an added measure to limit contraction. This type of therapy can provide significant relief to affected patients.
A question I get asked a lot by patients is “what would happen if I don’t wear a night guard or try conservative therapy?” This is a good question. Early on if the symptoms are limited to chewing muscles with time and without treatment muscles in the neck and shoulders will become involved and areas of referred pain can increase. Since there are a spectrum of TMD disorders there is also a progression of the disease. Up to this point we’ve only discussed muscular dysfunction but with untreated muscular dysfunction the patient can more easily progress to derangement of the joint and degenerative joint disease. Some of these conditions become severe enough to warrant surgery with an oral surgeon or ENT. If you’re having painful symptoms and suspect you may have TMD visit your dentist for an evaluation, it's important not to wait in case the pain is referred from a tooth that needs prompt treatment.