Interrelationships of Various Temporomandibular Disorders

The accurate diagnosis and treatment of TM disorders (TMDs) can be difficult and confusing. This is often true primarily because the patient’s symptoms do not always fit into one classification. In many instances several classifications seem to be appropriate because in reality the patient is suffering from more than one disorder. In fact, in many patients, not only do several conditions coexist, one disorder may actually contribute to another. It is appropriate, therefore, when more than one disorder appears to be present, to attempt to distinguish the primary from the secondary disorder. For example, a patient may complain of right temporomandibular joint (TMJ) pain 2 weeks after a fall that traumatized the joint. The pain has been present for 12 days, but during the past week it has been aggravated by a decrease in mouth opening associated with muscle discomfort. The primary diagnosis is a traumatic injury to this joint, whereas the secondary diagnosis is protective co-contraction or local muscle soreness associated with the response of the muscles to restricted movement of the painful joint. During treatment both diagnoses must be considered and appropriately managed.

The interrelationship of the various TMDs must always be considered in the evaluation and treatment of patients. Sometimes it is nearly impossible to identify which disorder preceded which. Often the evidence to determine such an order can be obtained only from a thorough history. The following examples demonstrate the complex interrelationships between several TMDs:

A patient suffering from a masticatory muscle disorder such as local muscle soreness or myofascial pain will commonly report a chief complaint of myalgia. These muscle conditions are likely to increase the tonicity of the elevator muscles, creating an increase in interarticular pressure of the joint. The condition may be further aggravated by hyperactivity of the superior lateral pterygoid muscle (bruxism), which can accentuate a subclinical disc derangement disorder (increased clicking).

Another patient complains of an early disc derangement disorder. If pain is associated with it, secondary muscle co-contraction can result in an attempt to prevent painful movements. If the muscle co-contraction becomes protracted, local muscle soreness can result. In this instance, a disc derangement disorder has created a masticatory muscle disorder.

When some disc derangement disorders progress, the bony articular surfaces of the joint may undergo changes. In other words, disc derangement disorders can lead to inflammatory disorders of the joint.

When masticatory muscle disorders persist, limited mandibular movement can become protracted and lead to chronic mandibular hypomobility disorders. Likewise, inflammatory disorders can also induce chronic mandibular hypomobility disorders.

Trauma is another condition that affects all these disorders. Trauma to any structure of the masticatory system can either cause or contribute to most of the other TMDs.

This diagram begins to depict the complicated interrelationships that may exist among the various TMDs. It demonstrates why many patients have symptoms that are associated with more than one disorder and how these relationships can make diagnosis and treatment decisions very difficult.

Treatment of Temporomandibular Disorders

The treatments that have been suggested for TMDs vary enormously over a great spectrum of modalities. In order for the clinician to confidently select an appropriate treatment he or she should demand adequate scientific evidence to support its use. This support should be found in evidence-based literature documenting the successes and failures of a described treatment. Unfortunately this is not always the case. There are numerous published articles suggesting success of a variety of treatment options that may not be soundly substantiated with scientific evidence. In an attempt to demonstrate this confusion, the present author went to the dental literature and developed a list of treatment options that have received at least some scientific support. When the list grew to 49, the search was ended. No wonder the profession is so confused regarding the management of TMDs.

It is also worth noting that the popularity of certain treatment methods can be found to be geographically regionalized. It is highly unlikely that this is appropriate, since epidemiologic studies do not report regionalization of any particular TMD. It can also be noted that treatment selection correlates strongly with the specialty of the doctor whom the patient has consulted. If the patient comes to an orthodontist, orthodontic treatment is likely to be administered; if to an oral surgeon, a surgical procedure is likely; if to a prosthodontist, occlusal therapy is likely to follow. There is no reason why patients with similar problems should receive different treatments in different regions. Nor is there any reason why patients with similar problems should be treated differently by different specialties.

Another interesting observation is that some treatments presented as new and revolutionary were actually presented to the profession years earlier and found to have little or no value. It seems that once a generation has passed, someone rediscovers the treatment, introduces it as new, and clinicians accept the idea and begin using this treatment for their patients. This is certainly unfortunate since, as a result, our patients must suffer and endure additional expense and sometimes irreversible dental procedures that are doomed to fail.