Research has been done regarding two major behavioral factors, personality traits and emotional states, as they might be related to causation of TMDs.

PERSONALITY TRAITS

Personality traits are considered to be more or less permanent features in individuals. Multiple studies have attempted to identify personality traits that are common to TMD patients. Many personality traits have been tested. Various studies have reported a relationship of this kind but the enormous variation of traits that supposedly demonstrate a correlation makes it impossible to conclude that any one or several traits predominate as common in and /or contributory to TMDs. Taken as a whole, TMD patients demonstrate a normal range of personality traits. Therefore, no personality trait test will aid in selecting treatment for an individual patient.

EMOTIONAL STATES

Emotional states, unlike personality traits, are usually of short duration in human behavior. Here, more consistent research results have been reported. In most studies, high levels of anxiety have been common in TMD patients. These studies have not been able to show whether anxiety is a contributor to the symptoms or has been the result of the pain. Both could be true. Other emotions that have been reported have been apprehension, frustration, hostility, anger and fear. This does not imply, however, that all, or even most, TMD patients exhibit such emotional states.

Although increases in emotional stress in some studies has been associated with increased parafunctional activity (clenching, bruxism), not all studies have demonstrated this association. An increase in muscle tonicity may also result from activation of the sympathetic nervous system that occurs with emotional states. Unfortunately, as with personality traits, no psychologic tests are able to determine whether these emotional states are contributing to muscle hyperactivity nor can they help in determining appropriate treatment.

Another emotional state that has been related to TMD is depression. Again, the presence of depression does not necessarily imply that it is the cause of the TMD symptoms. In fact, when a painful condition has become chronic, it is known that depression can be the result of the chronic pain, rather than the other way around. It is possible that pain and depression may co-exist without being related. If this appears to be the case, particularly if there also appear to be dental contributors, then the two conditions should be addressed simultaneously.

It is also known that a history of physical and/or sexual abuse (particularly in women) is linked to chronic facial pain, including headache. In some patients, a history of abuse can lead to post-traumatic stress disorder that contributes to an up-regulation of the autonomic nervous system, thus decreasing the body’s ability to overcome new challenges, both physical and psychological.

There is a common myth within the dental community that patients with TMD symptoms are somehow emotional invalids. This is unfortunate, because it is generally untrue. However, it is important for dentists to be aware that emotional states and/or a history of emotional trauma, when present, can play a role in the expression of a patient’s TMD symptoms. When appropriate dental approaches to treatment have not produced anticipated outcomes, consideration of the possibility of an emotional component should not be dismissed.

The challenge for a dentist, when emotional stress is suspected, is to know whether this is a result of stress from daily routines or from deeper, more profound emotional issues, in which case referral to a properly trained therapist may be indicated. Initially, however, several techniques that can address the causes of more common sources of stress can be considered. It is useful to introduce a discussion of these at the beginning of any treatment regimen, for all patients.

PATIENT AWARENESS

During the initial evaluation of the patient, if the history and clinical findings suggest primarily a muscular condition, and especially if there is reason to suspect parafunctional activities, some initial discussion is often appropriate to bring to the patient’s awareness the possibility that emotional stress can contribute to muscle hyperactivity and possibly to parafunctional behaviors. This information may be new to the patient. They should be made aware that this is common place and not an indication of neurotic or psychotic disorders. Instruction should focus on making them aware that their teeth should not contact other than when chewing, swallowing and speaking. Although they may initially deny that clenching or bruxing are something that they do, simply bringing this to their awareness and asking them to be more conscious of the possibility will often result in their becoming aware that they do, in fact, clench or brux. This is the first step toward altering such behavior.

RESTRICTIVE USE

Because pain in the masticatory system will tend to increase the protective muscle splinting or co-contraction response and often limits the functional range of motion, the patient should be instructed to avoid any jaw activity that may produce pain. Any such activity such painful activity can also activate central excitatory effects and cyclic muscle pain. All jaw activity should be limited to pain-free movements.

Restricted use of the jaw, in particular, applies to dietary considerations. The patient should be told, “nothing hard, tough, crunchy, or chewy”. They should be instructed to not chew chewing gum. Specifically, they should be told that their diet should consist of soft foods that require very little chewing and they should be instructed to chew slowly. Patient’s will often ask how long they need to continue this type of diet. They should be told that it will be necessary until it can be demonstrated that their jaw muscles are no longer painful to palpation, not just to their own perception that they are not experiencing pain. Patients will often test these limits and may report that they found that what they tried caused pain and was not a good idea. However, it is worthwhile to question them from time to time about their diet throughout treatment to be sure they are in compliance with these restrictions.

VOLUNTARY AVOIDANCE

When the patient has become aware of when they put their teeth together, other than when chewing, swallowing, and speaking, they can begin to take control of this behavior and voluntarily disengage the teeth. To accomplish a relaxed jaw posture they should be instructed to keep the lips passively together and the teeth apart. This relaxed jaw posture is further enhanced by puffing a little air through the lips. They should be encouraged to repeat this throughout the day.

The relaxed jaw posture decreases elevator muscle activity and therefore, with time, tends to decrease muscle pain while simultaneously decreasing intra-articular pressure. Less loading of the joints tends to encourage soft tissue repair.

Other oral habits, (biting on objects such a pencils or holding a telephone under their chin, etc.) should also be discouraged. Once recognized, habits of this kind will be easier for the patient to control than will be the voluntary disengagement of the teeth. Other recognized stress-inducing situations, such as driving in heavy traffic or uncomfortable personal encounters should also be avoided whenever possible.

RELAXATION THERAPY

Two types of relaxation therapy have been shown effective in reducing muscle pain. The first is learning to reduce the stress that leads to increased muscle tension. The second is to learn to relax the muscles directly. The purpose of achieving muscle relaxation is primarily to allow better blood flow through the muscle, thereby flushing out the metabolic waste products that can stimulate nociceptors in the muscle.

Learning to reduce stress is also referred to behavioral modification and can involve any activity that is enjoyed by the patient and allows him / her to let go of the stressful situations in their life. This might include hobbies, sports or other recreational activities. Regular exercise can be a very effective stress-relieving activity for those who enjoy it and are physically able to engage in it. For some individuals, being able to be alone and quiet may be stress relieving. All of these are considered external stress-relieving mechanisms.

Direct muscle relaxation can involve any of several known methods. Jacobson developed a technique in the late 1960s referred to as progressive relaxation. Several other techniques have since been developed that are variations of this method.

One of these involves having the patient lie quietly and listen to a guided relaxation audio recording that is specifically developed for this purpose. Hypnosis, meditation and yoga have all been used for this purpose, as well.

One of the most effective methods of achieving direct muscle relaxation is biofeedback. This employs the use of surface electrodes that are placed over muscles. These are connected to a device that provides either a visual or an audible feedback that lets the patient know when they are achieving a more relaxed muscular state. Many people who have hight levels of muscle tension don’t recognize this because they have lived with it for so long that it feels “normal” to them. Biofeedback training helps them recognize the difference between muscles that are tense and muscles that are relaxed so that they are better able to maintain muscle relaxation during their normal daily activities. Biofeedback training is often an effective adjunct to physical therapy and can be incorporated effectively with physical medicine by therapists who have that training.

There are difficulties in evaluating the role of emotional stress in TMDs. Therefore, other than the stress reduction methods described here, it is usually advisable to rule out all other contributing factors before considering making a referral to a trained professional for extensive emotional therapy.