TMJ Pain Temporomandibular Joint Pain
What is TMJ?. The temporomandibular joint (TMJ) is the most regularly used joint in the human body. the TMJ, connects the upper and lower jawbones which allows the jaw to open, move back and forth and sideways. It opens and closes about 1500 to 2000 times a day and is also instrumental in several functional movements such as chewing, swallowing, breathing, talking, or yawning. Because the TMJ is a very regularly used joint, its bone, muscle or cartilage may deteriorate over time, leading to disorders of the TMJ.
If you cover your ears with your palms, your thumbs will be on the base of your skull called the occiput. Your palms and fingers will lie across your temporal bones, and the heels of your hands will rest on the angle of your jaw called the mandible. The temporal bone and mandible interact at the temporomandibular joint called the tmj for short. You can locate this joint by lightly placing two fingers directly in front of your ears and open and close your mouth.
Temporomandibular joint disorders, or TMD, are common in adults; as many as one third of adults report having one or more symptoms, which include jaw or neck pain, headaches, and clicking, popping or grating noises within the joint. The joint has a capsule that contains an articular disc and surrounding muscles have a nerve supply which is thought to be the primary source of pain in TMJ disorders.
The cause of tmj pain, in most cases, is not clear. Some are thought to be joint capsule inflammation or damage and muscle pain or spasm may be caused by abnormal occlusion, teeth grinding (bruxism), teeth clenching, lip biting, stress, anxiety, or abnormalities of the disc in the joint.
The temporomandibular joint has been linked to different parts of the body, particularly the neck. Some suggest that posture training may be a positive impact on the muscles because a proper posture can play a relevant role in the relationship between the temporomandibular joint and the rest of the body. It appears that an intimate functional relationship exists between the jaw (mandibular) and the head and neck systems. Patients with temporomandibular disorders often report symptoms of neck pain. Furthermore, some studies have investigated the relationship between neck symptoms noting that mouth opening is always accompanied by head and neck extension and mouth closing by head and neck flexion. These studies suggest that functional jaw movements use mandibular, head, and neck movements involving the temporomandibular joint, the atlanto-occipital joints between the head and neck, and the lower joints of the neck. The studies have noted the contribution of the upper part of the neck, particularly the atlanto-occipital joint, for proper positioning of the TMJ.
Temporomandibular disorder (TMD) is a term that refers to 1 or more conditions that adversely affect the temporomandibular joint or the surrounding masticatory (chewing) musculature. In general, TMD symptoms consist of pain at rest and/or during jaw function, limited range or disturbances of mandibular motion, and noises from within the temporomandibular joint (TMJ). The most common and general categorization of TMD is to separate it into muscle disorders (myofascial disorders that affect the masticatory musculature) or TMJ articular disorders (those that directly affect the TMJ itself like arthritis). It should be noted that both muscle and joint problems can exist at the same time.
TMJ Joint – Joint disorders include arthritis and joint disc displacement.
The TMJ Joint has a disc which can be displaced and result in clicking or locking.
Patients with TMD who hold their heads farther forward relative to the shoulders (forward head posture) have a high probability of experiencing symptom improvement as a result of posture training and being provided with self-management instructions.
Poor neck posture is widespread in the general population and appears to be an adaptive, self-perpetuating trait that most people lack the cognitive ability or desire to correct by themselves. Many practitioners have speculated that poor posture may have a negative effect on temporomandibular, or TMD, symptoms and treatment outcome.
Forward head posture is the most common form of poor posture and is assumed by many authors to be related to a multitude of myofascial pain disorders. With this posture, the head’s center of gravity is forward of the spine’s weight-bearing axis, which increases the strain within the posterior cervical muscles, ligaments and joints. Studies have demonstrated that when the head is positioned forward, the upper trapezius muscle activity is significantly higher than it is when the head is in normal alignment and indicates that the patient is more likely have pain from overusing the muscles.
It has been demonstrated that neck muscle activity influences masticatory muscle activity. The additional demand that is placed on the neck by the forward head posture alters the masticatory system so that people are more susceptible to tmj muscle strain, spasm and pain. Posture training usually involves posture exercises performed repetitively to stretch structures that poor posture tends to shorten, strengthen structures that poor posture tends to weaken and create an awareness of the desirable posture.
Related to the neck and posture, a study in the Journal of the Canadian Dental Association, September 2008, Vol. 74, No. 7 “This web-based survey provides the first evidence that chronic pain in jaw muscles and other symptoms of TMD are associated with long-term, heavy use of computers. However, the great majority of people with these symptoms probably also suffer from pain in the shoulder and neck.”
In the journal Clinics (Sao Paulo). 2009 January; 64(1): 35-39. It is indicated there is an association between posture and tmj pain. Therefore evaluation of posture is an important aspect of for evaluating and managing temporomandibular disorders.
Also, relating to the neck, whiplash injury has also been associated with tmj pain. The mechanism is not clear, however, in Dynamic Behavior of the Temporomandibular Joint in 198 Frontiers in Whiplash Trauma N. Yoganandana nd F.A. Pintar (Eds.) IOS Press, 2000, indicate that it is mostly related to the neck. It is stated, “Positioning of a headrest very close to the head would provide a clear means of preventing mouth opening.” The authors indicate that mouth opening is observed during whiplash, but it does not exceed the physiological limits. The authors state “…TMJ dysfunction is more likely due to post-crash neuromuscular changes and/or pain referral of a cervicogenic [neck] nature.” Their reference to headrest positioning is noted to prevent jaw opening and it is also recommended to help prevent whiplash and this is why I highly recommend an add on headrest for vehicles with poorly rated headrests, like the Car Seat Head Support. So if you have neck or tmj problems, this device can help prevent further injury in the event of a rear end auto collision.
In the Journal of the American Dental Association, Vol. 138, August 2007, indicated One out of 3 whiplash trauma sufferers, which often cause neck problems, has a higher risk of having delayed onset TMJ pain within a year following the accident. It is well-known that trauma results in injury and pain. Clenching can be considered a form of microtrauma that results in pain. Third molar removal may involve wide opening of the mouth, application of considerable forces to the mandible, and, if performed under general anesthesia, a reduction in a subject’s protective mechanisms. Any of these could result in trauma to the TMJ or the muscles of mastication.
There is also an association to suggest that anxiety, stress, and other emotional disturbances may worsen TMJ disorders, especially in patients who experience chronic pain. There is also a high prevalence of tmj disorders among females as compared to males and the relationship is thought to be of a hormonal nature.
In a recent study in BMC Ear Nose Throat Disord. 2011 May 25;11(1):5. Signs and symptoms of temporomandibular joint disorders related to the degree of mouth opening and hearing loss. TMJ symptoms were more prevalent and problematic for women than men. The more the degree of mouth opening, the more severe the symptoms of TMJ pain. Mild levels of TMJ pain correlate to normal hearing tests, while more moderate or severe TMJ pain symptoms are related to hearing loss. Grinding of teeth (bruxism), degenerative changes in the joint (ankylosis), joint pain as well as itching of the ear are signs related to TMJ. The study further noted, that movements of the jaw or neck increases pressure on the hair cells in the inner ear which can cause tinnitus and vertigo.
Muscular origins of TMJ pain show 2 main muscles that can can form areas of strain with referred pain. The “x” shows the area of strain and the red indicates the areas of pain referral. Click on the pictures to make larger.
The masseter muscle can have areas of strain that result in restriction of jaw opening (trismus). Tinnitus may be associated with areas of strain in this muscle and is usually one sided. Development of strain in the masseter muscle can be from jaw clenching, sucking the thumb late in childhood, chewing gum habitually, clamping of the jaws on a pipe or cigarette holder, biting off thread by a seamstress, cracking nuts or ice between teeth, poor occlusion of teeth, prolonged dental procedures, emotional tension and referred pain from neck muscle strain of the sternocliedomastoid.
The temporalis muscle can have areas of strain that result in a headache that is felt widely throughout the temple, along the eyebrow, behind the eye and may cause pain in the upper teeth. Development of strain in the temporalis muscle can result from occlusal imbalance, clenching of the teeth, direct trauma from a fall on the head, impact from a golf ball or baseball, or by a car accident, excessive gum chewing, a cold draft over the muscle. Restriction of jaw opening, but not as much as with the masseter.
Determining the level of jaw restriction in TMJ pain.
The Three-knuckle Test. The fully opened jaw should admit the first three knuckles of the non-dominate hand in individuals with normal joint and bone structures and without areas of muscles strain. With areas of strain in the masseter muscle, usually only 2 knuckles can be admitted. If there are areas of strain in the temporalis muscle, usually only 2 and a half knuckles can be admitted. Grating or popping sounds during this test may indicate TMJ joint problems and require expert examination.
Although there is no clear method of treatment, we next explore methods for TMJ Pain Relief.