Management of Temporomandibular Disorders

Interview

The patient's history may be the most important part of the evaluation because it furnishes clues for the diagnosis. The history begins with the chief complaint, which is a statement of the patient's reasons for seeking consultation or treatment. The history of the present illness should be comprehensive, including an accurate description of the patient's symptoms. The following attributes of symptoms should be explored during the interview: location, quality and severity, quantity, timing, setting in which symptoms occur, remitting or exacerbating factors, and associated manifestations.

It is often helpful to have the patient point to the exact location where the symptom occurs, especially if the symptom is pain. Determining the origin of pain is more reliable if the patient points to one specific location (e.g., the joint capsule), rather than if the patient circles the entire left side of the face with a finger. Qualitative descriptors may also provide a clue as to the source of the symptom. For example, muscular pain is usually described as “dull” and “achy,” whereas acute joint pain may be “sharp” or “shooting.” The use of a visual analog pain scale, rating the pain level on a scale from 1 to 10, may also help obtain an understanding of the patient's perception of the severity of pain. The timing of the patient's perceived pain is also helpful in determining a cause. Pain that occurs primarily in the morning may indicate a systemic arthritis such as rheumatoid arthritis or myofascial pain resulting from nocturnal bruxism. If pain only occurs toward the end of the day, osteoarthritis may be explored as a potential cause. The setting in which a symptom occurs should also be noted. For example, a stressful situation might result in a patient initiating a parafunctional habit such as nail biting. Removing the patient from the stressful situation may be the only treatment indicated. Questioning the patient for remitting or exacerbating factors should also include any previous treatments and the response to those treatments. Lastly, TMDs are usually associated with other manifestations that may need to be addressed during treatment. Some of the more common associated symptoms include headaches, limited ability to open the mouth, and malocclusion. It is often helpful to have the patient fill out a general questionnaire with questions directed toward these issues to ensure that the appropriate information is gathered.

Examination

The physical examination consists of an evaluation of the entire masticatory system. The head and neck should be inspected for soft tissue asymmetry or evidence of muscular hypertrophy. The patient should be observed for signs of jaw clenching or other habits. The masticatory muscles should be examined systematically. The muscles should be palpated for the presence of tenderness, fasciculations, spasm, or trigger points ( Fig. 31.1 ).

The TMJs are examined for tenderness and noise ( Fig. 31.2 ). The location of the joint tenderness (e.g., lateral or posterior) should be noted. If the joint is more painful during different areas of the opening cycle or with different types of functions, this should be recorded. The most common forms of joint noise are clicking (a distinct sound) and crepitus (i.e., scraping or grating sounds). Many joint sounds can be easily heard without special instrumentation or can be felt during palpation of the joint; however, in some cases, auscultation with a stethoscope may allow less obvious joint sounds such as mild crepitus to be appreciated.

The mandibular range of motion should be determined. Normal range of movement of an adult's mandible is about 45 mm vertically (i.e., interincisally) and 10 mm protrusively and laterally ( Fig. 31.3 ). The normal movement is straight and symmetric. In some cases, tenderness in the joint or muscle areas may prevent opening. The clinician should attempt to ascertain not only the painless voluntary opening but also the maximum opening that can be achieved with gentle digital pressure. In some cases, the patient may appear to have a mechanical obstruction in the joint causing limited opening but, with gentle pressure, may actually be able to achieve near-normal opening. This may suggest muscular rather than intracapsular problems.

The dental evaluation is also important. Odontogenic sources of pain should be eliminated. Teeth should be examined for wear facets, soreness, and mobility, which may be evidence of bruxism. Although the significance of occlusal abnormalities is controversial, the occlusal relationship should be evaluated and documented. Missing teeth should be noted, and dental and skeletal classification should be determined. The clinician should note any centric relation (CR) and centric occlusion (CO) discrepancy or significant posturing by the patient. The examination findings can be summarized on a TMD evaluation form and included in the patient's chart. In many cases, a more detailed chart note may be necessary to document adequately all of the history and examination findings described previously.

Radiographic Evaluation

Radiographs of the TMJ are helpful in the diagnosis of intraarticular, osseous, and soft tissue pathologic conditions. The use of radiographs in the evaluation of the patient with TMD should be based on the patient's signs and symptoms instead of routinely ordering a standard set of radiographs. In many cases, the panoramic radiograph provides adequate information as a screening radiograph in evaluation of TMD. A variety of other radiographic techniques that are available may provide useful information in certain cases.

Panoramic Radiography

One of the best overall radiographs for screening evaluation of the TMJs is the panoramic radiograph. This technique allows visualization of both TMJs on the same film. Because a panoramic technique provides a tomographic-type view of the TMJ, this can frequently provide a clear assessment of the bony anatomy of the articulating surfaces of the mandibular condyle and glenoid fossa ( Fig. 31.4 ), and other areas such as the coronoid process can also be visualized. Many machines are equipped to provide special views of the mandible, focusing primarily on the area of the TMJs. These radiographs can often be completed in the open and closed positions.

Computed Tomography

Computed tomography (CT) provides a combination of tomographic views of the joint, combined with computer enhancement of hard and soft tissue images. This technique allows evaluation of a variety of hard and soft tissue pathologic conditions in the joint. CT images provide the most accurate radiographic assessment of the bony components of the joint ( Fig. 31.5 ). CT reconstruction capabilities allow images obtained in one plane of space to be reconstructed so that the images can be evaluated from a different view. Thus evaluation of the joint from a variety of perspectives can be made from a single radiation exposure.

Cone-Beam Computed Tomography

Cone-beam computed tomography (CBCT) scans have recently become a popular diagnostic tool among dentists and oral-maxillofacial surgeons, mostly because of their convenience, accuracy, and reduced cost. CBCT scanners are office-based scanners that are capable of providing tomographic views with three-dimensional reconstructions of the mandibular condyle and articular eminence ( Fig. 31.6 ). When evaluating bony structures, it has the diagnostic accuracy of conventional CT scanners but requires much less radiation exposure to patients. The major limitation to the CBCT scanner is that it does not provide diagnostic images of soft tissue structures.

Magnetic Resonance Imaging

The most effective diagnostic imaging technique to evaluate TMJ soft tissues is magnetic resonance imaging (MRI; Fig. 31.7 ). This technique allows excellent images of intraarticular soft tissue, making MRI a valuable technique for evaluating disk morphology and position. MRI images can be obtained showing dynamic joint function in a cinematic fashion, providing valuable information about the anatomic components of the joint during function. The fact that this technique does not use ionizing radiation is a significant advantage.

Nuclear Imaging

Nuclear medicine studies involve intravenous injection of technetium-99, a γ-emitting isotope that is concentrated in areas of active bone metabolism. Approximately 3 hours after injection of the isotope, images are obtained using a gamma camera. Single-photon emission CT images can then be used to determine active areas of bone metabolism ( Fig. 31.8 ). Although this technique is extremely sensitive, the information obtained may be difficult to interpret. Because bone changes such as degeneration may appear identical to repair or regeneration, this technique must be evaluated cautiously and in combination with clinical findings.

Psychological Evaluation

Many patients with temporomandibular pain and dysfunction of long-standing duration develop manifestations of chronic pain syndrome behavior. This complex may include gross exaggeration of symptoms and clinical depression. The comorbidity of psychiatric illness and temporomandibular dysfunction can be as high as 10% to 20% of patients seeking treatment. A third of these patients are suffering from depression at the time on initial presentation, whereas more than two-thirds have had a severe depressive episode in their history. Psychiatric disorders may elicit somatic components through parafunctional habits resulting in dystonia and myalgia, and individuals with chronic pain commonly have a higher incidence of concomitant anxiety disorders. Behavioral changes associated with pain and dysfunction can be elicited in the history through questions regarding functional limitation that results from the patient's symptoms. If the functional limitation appears to be excessive compared with the patient's clinical signs or the patient appears to be clinically depressed, further psychological evaluation may be warranted.

Myofascial Pain

Myofascial pain and dysfunction (MPD) is the most common cause of masticatory pain and limited function for which patients seek dental consultation and treatment. The source of the pain and dysfunction is muscular, with masticatory muscles developing tenderness and pain as a result of abnormal muscular function or hyperactivity. The muscular pain is frequently, but not always, associated with daytime clenching or nocturnal bruxism. The cause of MPD is multifactorial. One of the most commonly accepted causes of MPD is bruxism resulting from stress and anxiety, with occlusion being a modifying or aggravating factor. MPD may also occur because of internal joint problems such as disk displacement disorders or degenerative joint disease (DJD).

Patients with MPD generally complain of diffuse, poorly localized, preauricular pain that may also involve other muscles of mastication such as the temporalis and medial pterygoid muscles. In patients with nocturnal bruxism, the pain is frequently more severe in the morning. Patients generally describe decreased jaw opening with pain during functions such as chewing. Headaches, usually bitemporal in location, may also be associated with these symptoms. Because of the role of stress, the pain is often more severe during periods of tension and anxiety.

Examination of the patient reveals diffuse tenderness of the masticatory muscles. The TMJs are frequently nontender to palpation. In isolated MPD, joint noises are usually not present. However, as mentioned previously, MPD may be associated with a variety of other joint problems that may produce other TMJ signs and symptoms. The range of mandibular movement in patients with MPD may be decreased. In fact, limited range of motion is often more severe compared with an internal derangement. Also note that teeth frequently have wear facets. However, the absence of such facets does not eliminate bruxism as a cause of the problem.

Radiographs of the TMJs are usually normal. Some patients have evidence of degenerative changes such as altered surface contours, erosion, or osteophytes. These changes, however, may result from or be unassociated with the MPD problem.

Internal Derangements

In a normally functioning TMJ, the condyle functions in a hinge and a sliding fashion. During full opening, the condyle not only rotates on a hinge axis but also translates forward to a position near the most inferior portion of the articular eminence ( Fig. 31.9 ). During function, the biconcave disk remains interpositioned between the condyle and the fossa, with the condyle remaining against the thin intermediate zone during all phases of opening and closing. Frequently, patients with TMJ pain and dysfunction have an abnormal relationship among the condyle, the disk, and the fossa. This abnormal relationship is commonly referred to as internal derangement . Clinical manifestations of internal derangements have been found to vary, but in a characteristic way, according to the degree of pathologic change. As a result, staging criteria were developed with respect to clinical, radiologic, and surgical findings, as seen in Box 31.1 .