TMD and Facial Pain

Many different diseases and dysfunctions can cause facial pain. The head and neck are composed of many nerves, blood vessels, muscles , bones, and connective tissues, all of which can be the primary source of pain. Pain can be originating from; muscles of the temporomandibular joint (TMJ), muscles of the neck, TMJ, teeth, sinus, ear, neuralgia, vascular, lesions of central nervous system, plus many others. Understanding all the different diseases and dysfunctions that can cause facial pain is the first step in developing a list of the possible causes of a specific patients pain.

Temporomandibular disorders (TMD) are a group of diseases and dysfunctions that cause facial pain. TMD is not one disease, but many different diseases grouped into one classification. Why the maxilla was left out is not known. Ideally the term should be Temporo/Mandibular/Maxillary Disorder, as this more accurately describes the anatomic regions involved.

The American Dental Association’s President’s Conference on Temporomandibular Disorders defined TMD as a group of orofacial disorders characterized by:

Pain in the preauricular area (in front of the ear), TMJ, or muscles of mastication

Limitations/deviations in mandibular range of motion

TMJ sounds during jaw function

The classification of TMD is an attempt to group together diseases and dysfunctions together that are in the area of expertise that a dentist would treat. I see two main problems with TMD as presently defined. First is that the inclusion criteria is too broad. Pain in the preauricular area (in front of the ear) will include many disease that a dentist is not qualified to treat. An example would be otitis media (middle ear infection) causing preauricular pain. Second is that  there are no clear cut boundaries where a dentist expertise ends and another specialty begins. An example is muscle splinting to protect a damaged temporomandibular joint (TMJ) will involved neck muscle which will cause a dysfunction in the neck muscles. Alternately damage to the neck bones will cause muscle splinting in the neck that will affect the TMJ and its function.  A list of possible TMDs is seen in table 1.1. While this is not a complete list, it does include the most common.

Problems involving the TMJ are but one of many types of TMD. It is important to emphasize that TMD is not one disease with one treatment. Patients routinely present with a previous diagnosis of “TMJ” or “TMD.” Telling a patient that he or she has “TMJ” is equivalent to a physician telling a patient he or she has “knee.” TMJ and TMD are not accurate orthopaedic diagnoses, and clinicians should not use them as a diagnosis.

Someone experiencing Facial Pain may or may not have a TMD.

Someone with a TMD may or may not have damage to the TMJ, and may or may not have facial pain.

Someone with damage to the TMJ will have a TMD, but may or may not have facial pain.

The majority of patients (70%) with TMD facial pain have myalgia (soreness) of the TMJ muscles. Any therapy that makes muscles feel better will help. These therapies however may only be masking the cause of the problem. While the patient may feel better, therapy is continually needed to maintain a degree of comfort as the cause of the problem has not been identified and resolved. Muscle relaxants are a good example of a treatment that makes the muscles feel better, but is not a long term solution.

Along with the muscles, TMJ damage also plays a significant role in many facial pain patients.

Significantly more patients with TMD facial pain have a damaged TMJ (86%) as compared to non-TMD patients (34%).

You can have a damaged TMJ and not have pain. In fact, a majority (70%) of damaged joints adapt favorably over time with out any therapy. However 30% of damaged TMJ do not adapt favorably, and a few (3%) will have serious problems including chronic pain and facial deformity.