The most common symptoms of TMJ disorders are headaches (including common migraines), facial pain, difficulty chewing and swallowing, limited mouth opening, "phantom" tooth pain, blocked eustachian tubes (stuffy ears), dizziness, ringing or buzzing sounds in the ears, subjective hearing loss, and postural stresses such as chronic neck tension. All these symptoms rarely occur together in one patient, and most patients suffer from only a few of them. For example, some only experience headaches, some only experience facial pain, and some only experience ear problems. A few people also suffer from symptoms such as facial twitching and visual problems that are apparently related to the TMJ condition, because they respond quickly to treatment of the TMJ condition, even though we do not fully understand the mechanism of their involvement.
Dislocated disks and arthritic degeneration of the TMJs usually do not cause pain directly in the TMJs. Since joint surfaces are designed to withstand large compressive forces, they do not have sensory nerves in the area between the bones. Instead, their pain sensitive nerves are confined to the capsule at the outer edges of the joint. These sensory nerves signal pain only when the joint capsule is stretched by swelling inside the joint. Swelling inside the joint also pushes the affected condyle down and away from the skull, thereby slightly changing the cant of the long lower jawbone and causing the teeth to fit differently or not at all. Most frequently, the back teeth cannot touch on the affected side because of the swelling, and biting forcefully to make them touch causes pain directly in the TMJ area, because the condyle is being driven into the area of inflammation.
JAW MUSCLE TENSION
Perhaps the most common symptom in TMJ disorders and the most direct effect of dislocated disks and arthritic degeneration of the TMJ is jaw muscle tension. Damage to tissue in any joint produces a reflex tightening of the muscles which cross that joint. You can see this effect in the way walking on a hurt knee automatically produces leg muscle tightening that results in limping. The muscles which cross the TMJ are the jaw muscles. When they must function on a dislocated TMJ, they hold themselves braced in readiness to protect the damaged joint, so they can never fully relax. As a result, their resting circulation is impaired and they may not be able to adequately flush the waste products out of their tissues.
The reflex tightening of the jaw muscles caused by TMJ disk dislocation explains why earlier muscle oriented TMJ treatments usually provided only limited success. Treating the jaw muscles provided short term relief, because it helped flush waste products out of muscles which had been operating with insufficient circulation, but it ignored the cause of the muscle tightness. Treating the jaw muscles without also improving the conditions in the joint was like massaging the leg muscles of someone who has an untreated broken ankle. The massage helps relieve the pain, but the muscles tighten up again as soon as the patient gets off the table and starts walking again. Muscles are full of sensory nerves and all connected in long functional chains, so pockets of accumulated waste products which build up in the jaw muscles can cause pain at locations far from the jaw area.
Since the jaw muscles attach all over the sides of the head, jaw muscle tension can apply significant pressure to the head. In monkeys, biting forcefully causes the whole head to bend measureably. Human jaw muscles are less powerful, but they are still important regulators of blood flow to and from the head. We do not understand much about the mechanisms behind headache, but disruption of blood flow regulation from excessive resting tonus of the temporalis muscles is likely one of the reasons that headaches have proven to be a primary symptom of TMJ disorders. The headaches which can be caused by TMJ disorders do not seem limited to certain types. It seems like to more we use sophisticated equipment to evalaute headaches, the fewer differences we can find between them. A surprising number of different headache types (including common migraine) have proven responsive to TMJ disorder treatment.
The tightening of the jaw muscles always affects head posture, because the jaw muscles form an integral part of the head posture mechanism. The interdependent relationship between jaw posture, head posture, and full body posture is explained in detail in the paper entitled JAW AND BODY POSTURE.
TMJ disorders can also cause a number of ear symptoms, although we do not always understand the mechanism. Many TMJ disorder patients have ear symptoms that worsen along with the other TMJ symptoms when a triggering event causes an exacerbation of the TMJ disorder and disappear when the TMJ disorder is relieved.
The balance mechanism, located in the inner ear, may be affected. Severe injury to the balance mechanism results in dizziness and nausea. Mild injury to that same system produces feelings of disorientation, inability to concentrate, a tendency to bump into things, and "spaciness". Tinnitus (ringing, roaring, or buzzing sounds in the ears) has been shown to respond to TMJ treatment in about half of the patients studied.
One cause of ear symptoms in TMJ disorders is probably sterile inflammation from chronic bruising of the retrodiskal tissues. Anatomical studies of TMJs with dislocated disks have shown that most of the tissue bruising in TMJ disorder patients occurs at the extreme back end of the TMJ, located only 1.5 millimeters from the front of the middle ear. The increased fluid pressure that results from inflammation can transmit pressure across the thin membrane bones separating the ear from the TMJs. Increased fluid pressure can push closed the eustachian tube, which passes very close to the back of the TMJ, or just make it so narrow that it can be blocked by a cold, allergy, or anything else that causes inflammation of the inner lining of the tube and thereby further narrows its lumen. Blockage of a eustachian tube can prevent it from equalizing pressure between the middle ear and the outside air and thereby create a stuffy feeling in the ear and difficulty clearing it after changes in altitude.
Another cause of ear symptoms in TMJ disorders may be tightening or loss of proper resting tonus of the two tiny ear muscles (the tensor tympani and the tensor veli palatini) which are controlled by the same motor nerve that controls the jaw closing muscles. Increased tension in that motor nerve due to reflex protective bracing in response to TMJ tissue damage may caused increased tension in both ear and jaw muscles. In the subjective hearing loss which is frequently found in TMJ disorder patients, hearing tests are normal even though patients report that they frequently miss things people say. This problem could be caused by disruption of the background tonus maintained by the tensor tympani muscles which control hearing by selectively applying tension to the eardrum. The eustachian tube dysfunction that is commonly found in TMJ disorder patients could be caused by disruption of the background tonus of the tensor veli palatini muscles which are necessary for opening the eustachian tube during swallowing.
Still another cause of ear symptoms in TMJ disorders may be Pinto's ligament, a fibrous continuity between the sphenomandibular ligament and the anterior malleolar ligament of the middle ear reported in 1997. The petrotympanic fissure between these structures appears to close at about the age of three, but some fibers may continue to pass through it and exert some pressure across it.
Some TMJ disorder symptoms are good indicator symptoms - they provide a good indication if the treatment is successfully treating the condition. Others symptoms are not good indicators. TMJ disorders have a whole constellation of symptoms associated with them. Some people get only one, some get several. Of the symptoms that you have from your particular TMJ disorder, whatever makes the condition worse will make the symptoms worse, and whatever makes the condition better will make the symptoms better, but some of the symptoms respond faster than others. We can use those more rapidly responding symptoms as indicator symptoms to be sure the treatment is on the right track. Pain is the best responder, tinnitus is the most irregular.
It seems like TMJ disorders have many diverse causes. Often the symptoms are preceeded by an event such as a blow to the head or face, whiplash, a long dental appointment, a period of excessive central nervous system stress, postural strains, or a change in the bite. However, in the vast majority of TMJ disorder patients, such events are triggers like the straw that broke the camel's back. The ultimate cause is a dysfunctional facial growth pattern that produces progressive dysharmony between the jaws and other parts of the face. The dysharmony creates chronic mechanical strains between parts of the face, jaws, and TMJs which lack the goodness of fit normally found in other joints of the body. The role of facial growth in the genesis of TMJ disorders is explained extensively in the chapters 3 and 4 of the paper entitled ETIOLOGY under the drop down menu entitled FOR DOCTORS.
THE ROLE OF ADAPTATION
Because of the role of chronic mechanical strain in TMJ disorders, adaptation is an important factor in the genesis of symptoms. Frequently a bite that forces the lower jawbone into a retrusively strained bracing position with each mouth closing exists without causing symptoms for many years before a failure to adapt to the resulting mechanical strain permits tissue damage and clinical symptoms. Because of the role of adaptation in TMJ disorders, anything that diminishes adaptive capacity (such as central nervous system stress or an unrelated injury) can increase symptoms, and anything that enhances adaptive capacity (including nutritional support, relaxation, aerobic exercise, etc,) can eliminate symptoms.
THE ROLE OF STRESS
Because of the important role of adaptation, stress triggers TMJ disorder symptoms by diminishing adaptive capacity and thereby diminishing the ability to cope with a chronically strained jaw system. Stress also can trigger TMJ disorder symptoms by increasing the resting background tonus in the jaw muscles. Stress increases the resting tensions in all of the body's muscles. If a group of muscles is already operating at bordeline resting circulatory capacity, even a slight elevation in their resting tension from increased central nervous system stress can cause them to become symptomatic by lowering resting circulation below a threshold level.
Stress also affects jaw posture by holding the lower jawbone further closed at rest - sometimes so far that the teeth rest in contact. In other parts of the body, stress does not alter the positions of bones. Instead, it holds bones more tightly between equally strong muscles pulling in opposite directions. However, the jaw muscles are not similarly balanced between openers and closers. Because the powerful jaw closing muscles are all vertically arranged and dwarf the jaw opening muscles, an increase in stress holds the lower jawbone further closed. This may increase the pressure in the TMJs and thereby exacerbate the TMJ condition by increasing tissue damage there, as explained below in the paragraph entitled REACTIVE JAW MUSCLE TIGHTNESS.
THE ROLE OF AGE AND GENDER
TMJ disorders are age and gender dependent conditions. In all TMJ clinics all over the world, the vast majority of patients are women between the ages of 20 and 50. Because children have remarkable adaptive growth capacities, they rarely develop symptoms. No matter how much mechanical strain the jaw system must endure, rapid facial growth accomodates the strain in a way that maintains functional capacity and prevents damage to tissues.
Symptoms usually begin to appear after the teenage growth spurt when male and female facial growth patterns diverge significantly. Females acquire growth patterns that are typical of weaker jaw muscles with a more clockwise facial rotation. Then symptoms persist, especially in females, well into adulthood as slow strained facial growth continues to require adaptation. Finally, symptoms disappear in the elderly, because the decrease in neuromuscular reactivity which naturally occurs in older people means their jaw muscles no longer respond to arthritic changes in the TMJs by reflex bracing that increases resting tensions in the TMJs. Even though their TMJs keep undergoing more arthritic damage every year as seen on imaging like X-rays or MRI, the TMJ disorder symptoms disappear. Older people may have difficulty with mechanical operation of the joints, shifting of the bite, occasional pain, and some ear problems like dizziness or difficulty hearing, but the symptoms almost always just need minimal treatment to resolve. In most cases, all they need is to have their bites adjusted to fit their TMJs so they can chew well.
DISLOCATION OF THE TMJ DISK
The precipitating event for the vast majority of TMJ disorders is a dislocation of the disk from one or both of the TMJs. Joints are designed to hold a cushion (in this case a flexible fibrous disk) between two opposing bones so those bones do not rub directly together. After that disk has become dislocated, it no longer stays between the jawbones, and the affected joint functions like a door off its hinges. However dislocated disks do not necessarily cause significant pain or other symptoms. About 25% of adults have at least one dislocated disk, yet most do not suffer from it. They may report that they had pain for a year or ten years, but the symptoms usually resolve.
REACTIVE JAW MUSCLE TIGHTNESS
The increased jaw muscle tension that automatically results from TMJ damage is often the primary source of symptoms. A dislocated disk can cause jaw muscle tightness due to the reflex splinting or bracing which occurs automatically in the muscles surrounding any injured joint – much like the automatic leg muscle bracing you would experience as limping if you tried to walk on an injured ankle. Since the jaw muscles are oriented vertically, jaw muscle tightness increases the pressure between the uncushioned bones at the TMJ, thereby increasing tissue damage, causing more jaw muscle tightness and resulting in a vicious cycle that maintains the symptoms.
Subsequently, anything that breaks the cycle (even an injury to nearby tissues or a treatment for a different problem) can provide quick temporary relief. The fact that so many different treatments are able to provide similar short term relief by temporarily interrupting the pain cycle has led to much confusion regarding treatment for TMJ problems.