Temporomandibular joint (TMJ) (Figure 1) disorders may be encountered in a dental office during the diagnosis and treatment planning phase or may occur during dental treatment.1 These disorders may consist of 1) TMJ sounds, 2) change in jaw range of motion, 3) referred pain to the TMJs, masticatory muscles, teeth, and ears, and 4) changes in the occlusion. This presentation will highlight the former while leaving the reader to explore Part II for information on motion, pain, and occlusion.
Temporomandibular joint sounds are common in any population, regardless of age or gender. These sounds may take the form of articular crepitus (a grating noise) or may consist of distinct popping or clicking sounds. Crepitus-type sounds are usually associated with degenerative joint disease or osteoarthritis, whereas popping sounds may be associated with TMJ disc displacement or morphologic changes in the articular surfaces of the joint. There are other types of sounds that may be felt or heard in the TMJs, with or without any amplification, that are usually difficult to classify or diagnose.
Crepitus-Type Joint Sounds
Osteoarthritis of the TMJ, as in other synovial joints, is probably caused by overloading that exceeds the adaptive capacity of the joint.2 Osteoarthritis3 may be primary (ie, without a known cause) or secondary to trauma, infection, rheumatoid arthritis, or disc displacement. Signs and symptoms of osteoarthritis vary, depending on the amount of inflammation or destruction present. Generally, the main symptoms are joint pain and tenderness on palpation, joint sounds, and limitation of jaw movement. Diagnosis is based on these symptoms, particularly in the presence of radiographic evidence of structural bony changes, such as articular surface sclerosis or flattening, osteophytes (Figure 2), and erosive changes (Figure 3).
Lesions due to osteoarthritis increase with age and are asymptomatic for long periods of time.4 Toller believed that pain symptoms of osteoarthritis of the TMJ are often confined to a period of a “couple” of years, after which time the pain disappears.5 Patients may seek treatment due to pain or difficulty with jaw movements. For those patients, pharmacologic management with nonsteroidal antiinflammatory drugs, physical therapy, soft diet, and occlusal splints may be helpful. In cases where the symptoms continue, relief may be obtained with intraarticular injections or sometimes by surgery. When symptoms abate, replacement of the missing teeth and occlusal adjustment of the remaining teeth may become necessary.
The role of occlusal interferences and partial loss of teeth in the causation or progression of osteoarthritis is debatable, however, due to the variation in the adaptive capability of the individual and the tendency of osteoarthritis to reach a stage where destruction is no longer progressive. In the 38-year-old male patient presented, the posterior teeth never erupted to occlude with the opposing teeth (Figure 4). Other than fragmentation of the anterior teeth, no complaints or symptoms were present. A metal/acrylic prosthesis was fabricated that provided posterior occlusal contact and slightly discluded the anterior teeth (Figure 5). The appliance depended on the morphologic undercuts of the facial and lingual surfaces of the posterior teeth for retention. It required relining once a year; self-curing acrylic resin was used with acceptable results (Figure 6).
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Popping-Type Joint Sounds Caused by Disc Displacement
The most common source of popping sounds of the TMJ is probably anterior displacement of its articular disc. Definitive diagnosis of disc displacement is made by magnetic resonance imaging (MRI) of the TMJ,6 which is noninvasive and has a high degree of specificity and sensitivity. However, MRI is not usually utilized, due to the high cost and the ability of the clinician to arrive at a correct diagnosis using the clinical criteria. Clinical diagnosis of anterior displacement of the TMJ disc is based on finding: 1) an opening click, 2) a closing click that occurs at a much smaller interincisal distance than the opening click, 3) a click on translatory condylar movement but not on rotatory movements, and 4) abatement of the click when the vertical dimension of occlusion is increased by a few millimeters (as when biting on a cotton roll) or opening and closing the mandible in a slightly protruded position (Figures 7 and 8).
In absence of pain or dysfunction, such as locking or limitation of jaw opening, anterior displacement of the TMJ disc does not require any direct treatment, since: 1) The retrodiscal tissues of the TMJ change to nonvascularized, noninnervated, fibrous tissues, capable of performing the functions of the disc. 2) Clicking noises have been demonstrated to return following splint therapy or surgical intervention, regardless of the improvement in pain and dysfunction. 3) A significant percentage7,8 of asymptomatic TMJs have been found to have anterior disc displacement in magnetic resonance surveys.
Patients with painless popping sounds of the TMJ due to disc displacement require counseling in methods that may aid the natural healing of the joint and prevent further deterioration. Such counseling should be directed toward enabling the patient to relax the jaw and to keep the teeth apart at all times except during function. The importance of this advice cannot be overemphasized. Patients should also be reassured that in the majority of cases disc displacement is not necessarily progressive, particularly as it relates to pain.9
Should restorative dentistry be required in patients with asymptomatic popping sounds of the TMJ due to disc displacement, exercising additional precautions may be prudent. These include reduction of the time of each visit, application of moist heat during dental procedures, taking nonsteroidal antiinflammatory drugs prior to and during the procedure, and wearing a passive occlusal splint (stabilization splint) (Figure 9) for a period of time. The need for these precautions varies with the complexity of the restorative procedure planned. A MRI survey of the TMJs is advisable for documentation purposes prior to extensive restorative procedures.
Popping-Type Joint Sounds Caused by the Articular Surfaces
Another common source of popping-type sounds emanates from the articular surfaces of the TMJ. These sounds probably occur due to an abrupt change in the velocity of the movement of the condyle as it passes over the apex of a steep articular eminence when opening the mouth widely. An additional reason for these sounds is the presence of irregularities in the articular surfaces (Figure 10). These sounds are benign and are usually painless, requiring no additional treatment other than patient education and reassurance. These sounds are distinguished from those occurring due to disc displacement by the closing click, which occurs at approximately the same interincisal distance as the opening click. In disc displacement, the closing click almost always occurs closer to maximum intercuspation of the teeth. For example, an opening click at approximately 23 mm of interincisal distance during opening and a closing click, occurring in the same joint at approximately 23 mm of interincisal distance, probably are an indication of an irregularity of the articular surfaces. However, an opening click occurring at 23 mm and a closing click occurring at 5 mm probably indicate an anterior displacement of the TMJ disc.
Other Types of Joint Sounds
Other types of popping-type sounds may be heard or felt by the dentist, with or without amplification. The exact diagnosis of these sounds may not be readily understood; a possible explanation is that bruxism and occlusal interferences, causing joint extraloading or interference with joint lubrication, may be the major etiologic factors. In particular, a bout of nocturnal bruxism may produce a certain type of TMJ sound that is manifested initially in sluggishness or stiffness in jaw movement on awakening. In attempting to open the jaw, a pop may be heard, followed by normal jaw movement. Jaw movement remains normal and without any other symptoms until another bout of nocturnal bruxism occurs. A stabilization splint worn to sleep may be helpful in these circumstances as well as counseling in relaxation techniques.
Other sounds that may be heard in the TMJs may be difficult to classify. A clinical examination and a panoramic radiograph may assist in establishing a diagnosis. If these prove to be within normal limits, in the absence of bruxism, pain, or other signs of dysfunction, no treatment is required. However, if these joint noises are accompanied by pain or joint movement reduction, an MRI may be required, particularly if conservative methods (passive splint, medications, and physical therapy) do not relieve the symptoms.
In an average dental practice, the clinician may encounter signs and symptoms related to the TMJ, the masticatory muscles, or the occlusion. The suggestions in this article—as well as Part II that may be beneficial if reviewed in sequence—will enable the clinician to arrive at a diagnosis, counsel the patient, and administer the treatment, if necessary.
*Private Practice, New Orleans, Louisiana
- Bell WE. Temporomandibular Disorders: Classification, Diagnosis, Management. 3rd. ed. Chicago, IL: Year Book Medical Publishers; 1990:167.
- Stegenga B. Temporomandibular Joint Osteoarthritis and Internal Derangement. Groningen, Netherlands: Drukkerij Van Denderen, BV; 1991:16.
- American Academy of Orofacial Pain. Orofacial Pain: Guidelines for Assessment, Diagnosis, and Management. Carol Stream, IL: Quintessence Publishing; 1996:127-141.
- Widmalm SE, Westesson PL, Kim IK, et al. Temporomandibular joint pathosis related to sex, age, and dentition in autopsy material. Oral Surg Oral Med Oral Path 1994;78(4):416-425.
- Toller PA. Osteoarthritis of the mandibular condyle. Br Dent J 1973;134(6):223-231.
- Dolwick MF. Temporomandibular joint disc displacement: Clinical perspectives. In: Sessle BJ, Bryant PS, Dionne RA, eds. Temporomandibular Disorders and Related Pain Conditions. Seattle, WA: IASP Press; 1995:79-85.
- Kircos LT, Ortendahl DA, Mark AS, Arakawa M. Magnetic resonance imaging of the TMJ disc in asymptomatic volunteers. J Oral Maxillofac Surg 1987;45(10):852-854.
- Tallents RH, Katzberg RW, Murphy W, Proskin H. Magnetic resonance image findings in asymptomatic volunteers and symptomatic patients with temporomandibular disorders. J Prosthet Dent 1996;75(5):529-533.
- de Leeuw R, Boering G, Stegenga B, de Bont LG. Clinical signs of TMJ osteoarthritis and internal derangement 30 years after nonsurgical treatment. J Orofac Pain 1994;8(1):18-24.