Temporomandibular disorders: a clinical update

History

The main complaint may include orofacial pain, joint noises, restricted mouth opening, or a combination of these, in addition to other less specific problems such as headache and tinnitus. Pain should be evaluated carefully in terms of its onset, nature, intensity, site, duration, aggravating and relieving factors, and, especially, how it relates to the other features such as joint noise and restricted mandibular movements. More specifically, pain that is centred immediately in front of the tragus of the ear and projects to the ear, temple, cheek, and along the mandible is highly diagnostic for temporomandibular disorder. The pain may be accompanied by a click or grating sound in the preauricular region during mandibular functions such as chewing or yawning. A history of limited mouth opening, which may be intermittent or progressive, is also a key feature of temporomandibular disorders.

Chronic head, neck, and back pain; irritable bowel syndrome; and idiopathic pruritus are sometimes found in patients with temporomandibular disorders and should be sought by the doctor to help establish the possibility of a psychogenic cause. The doctor should also ask the patient about underlying influences such as stress, anxiety, depression, or important life events so that he or she can get a clearer picture of any psychogenic basis to the disorder.11131516 In general, the longer the duration of the symptoms and the greater the number of treatments, and in particular “failed” treatments, the smaller the likelihood that the patient will respond well to further treatment.16

Clinical examination

The patient should be evaluated for tenderness in those areas of the head and neck that are accessible to palpation. Palpation is accomplished by placing the finger tips in the preauricular region just in front of the tragus of the ear. The patient is then asked to open their mouth and the finger tip will fall into the depression left by the translating condyle. Examination of the masticatory musculature may also be accomplished by digital palpation. Areas of tenderness, trigger points, and patterns of pain referral should be noted.

Joint sounds and their location during opening, closing, and lateral excursions of the mandible may be either palpated or detected with a stethoscope placed over the preauricular area. Mandibular function may be evaluated by noting whether the line of vertical opening is straight and smooth or deviates with jerky movements. The range of painless maximal vertical opening (normal range 42-55 mm interincisal distance) should be recorded.

Investigations

Investigations are mainly required to eliminate the possibility of other abnormailties that may mimic temporomandibular disorder symptoms.214 Despite the limitations, plain radiographs of the temporomandibular joint such as high level orthopantomograms and transcranial projections are useful ways of visualising any gross pathological, degenerative, or traumatic changes in the bony component of the temporomandibular joint complex.17 In recent years, magnetic resonance imaging has been used increasingly to investigate temporomandibular disorders, in particular, internal derangements of the temporomandibular joint. 1819 Many other investigations such as computed tomography2021 and arthroscopy 2223 have been advocated, but arranging these should be left to specialist oral and maxillofacial surgeons.

Diagnosis

Myofascial pain and dysfunction generally presents with diffuse pain that is cyclic and found in several sites in the head and neck, particularly the muscles of mastication. Pain is frequently worst in the morning, and the patient will often report sore teeth from clenching. There is often a history of stress and difficulty in sleeping. The patient will present with diffuse muscle tenderness and a decreased range of mandibular movements with wear facets on the teeth.

Internal joint derangement, however, presents with continuous pain that is localised to the temporomandibular joint and is exacerbated by jaw movement. Mechanical interferences in the joint, such as clicking and locking, will often result in restricted mandibular opening or deviation of mandibular movements during opening and closing.

Crepitus or grating sounds emanating from the joint(s) during mandibular function is pathognomonic of temporomandibular joint osteoarthrosis in the elderly. Where the condition is painful, it is referred to as osteoarthritis. Computed tomograms of the temporomandibular joint will often show degeneration and flattening of the condylar head. Most patients seem to cope well with osteoarthrosis as it rarely leads to limited mandibular function. Where computed tomograms show similar condylar changes in younger patients, other arthridities, such as rheumatoid arthritis, should be considered and investigated further.

Differential diagnosis

When examining patients with suspected temporomandibular disorders, the practitioner must bear in mind the possibility of other common disorders such as dental pain; disorders of the ears, nose, and sinuses; neuralgias; headaches; and diseases of the major salivary glands all of which may mimic the symptoms of temporomandibular pain and dysfunction. What distinguishes temporomandibular disorders from other possible diseases is the pain, which is specifically centred in and around the preauricular region and may be accompanied by clicking or grating sounds with mandibular function and restricted mouth opening.

Treatment planning

The clinical course of temporomandibular disorders does not reflect a progressive disease, but rather a complex disorder moulded by many interacting factors that serve to maintain the disease.1 8122426 The main goals of treatment for temporomandibular disorders are to reduce or eliminate pain or joint noises, or both, and to restore normal mandibular function. This is best achieved when other contributing factors such as stress, depression, and oral parafunctional habits (such as bruxism) are addressed and incorporated into the overall treatment strategy.27 The doctor must establish whether the fundamental problem is organic or psychogenic as this will dictate treatment. Psychogenic disorders are mostly found in patients with myofascial pain and dysfunction. These patients need psychotropic medication and psychotherapy, which is described below.

Explanation and reassurance

Probably the most important part of the treatment of temporomandibular disorders is to explain to the patient the cause and nature of the disorder, and to reassure them of the benign nature of the condition. Many patients will benefit from the reassurance that the symptoms of the temporomandibular disorder they are experiencing is not a “cancer.” A thorough evaluation should effectively rule out more sinister possible causes.

Patient education and self care

A self care routine should include the following: limitation of mandibular function, habit awareness and modification, a home exercise programme, and avoiding stress. Voluntary limitation of mandibular function is encouraged to promote rest or immobilisation of muscular and articular structures–much the same as an athlete would rest an injured joint. Hence, the patient is advised to eat soft foods and avoid those that need a lot of chewing, and is discouraged from wide yawning, singing, chewing gum, and any other activities that would cause excessive jaw movement. Massaging the affected muscles and applying moist heat will promote muscle relaxation and help soothe aching or tired muscles. Patients should also be advised to identify the source(s) of stress, and try and change their lifestyle accordingly.

Drug treatment

If used properly as part of a comprehensive management programme, drugs can be a valuable help in relieving symptoms.1252829 No single drug has been proved to be effective for all cases of temporomandibular disorders. Practitioners treating patients with temporomandibular disorders should be conversant with the different families of drugs including non-steroidal anti-inflammatory drugs, opiates, muscle relaxants, tranquillisers, and antidepressants.

The analgesic effects of non-steroidal anti-inflammatory drugs is specific only in cases of temporomandibular disorders where pain is the result of an inflammatory process such as synovitis or myositis. For moderate to severe pain, opiates are best prescribed for a short period because of they can be highly addictive. At the doses usually prescribed clinically, opiates are more effective in dampening the patient's emotional response to pain than eliminating the pain itself. Where high levels of emotional stress are associated with temporomandibular disorders, tranquillising drugs such as benzodiazepines, or less commonly phenothiazines, are used to help the patient cope with stress by reducing their perception or reaction to it. Low doses of tricyclic antidepressants also help chronic orofacial pain such as that found in longstanding cases of temporomandibular disorders (table). Tricyclic antidepressants are best prescribed in gradually increasing doses over three and sometimes up to six months.

The danger of drug abuse is compounded by the “take as needed” philosophy of prescribing. This tends to provide brief periods of relief, but with more frequent pain cycles, decreased effectiveness, and ultimately overuse or abuse of the medication.252829 Medication prescribed for temporomandibular disorders should be taken at regular intervals–not “as required”–and for a specified period of time.29

Occlusal therapy

The most common form of treatment provided by dentists for temporomandibular disorders is occlusal appliance therapy. This may be referred to as a bite raising appliance, occlusal splint, or a bite guard. It is a removable device, usually made of hard acrylic, that is custom made to fit over the occlusal surfaces of the teeth. Although occlusal appliance therapy has been shown clinically to alleviate symptoms of temporomandibular disorders in over 70% of patients, the physiological basis of the response to treatment has never been well understood. 3031

Physiotherapy

The aim of physiotherapy is to restore normal mandibular function by a number of physical techniques that serve to relieve musculoskeletal pain and promote healing of tissues.32 Close cooperation with a physiotherapist who is well versed in the management of musculoskeletal disorders of the head and neck is essential.

Behavioural therapy

Where persistent habits exacerbate or maintain the temporomandibular disorder and these cannot be modified easily by simple patient awareness, a structured programme of cognitive behavioural therapy may be required. Behavioural modification strategies may include counselling on lifestyle, relaxation therapy, hypnosis, and biofeedback.33

Psychotherapy

Occasionally, temporomandibular disorders may be the somatic expression of an underlying psychological or psychiatric disorder such as depression or a conversion disorder.34 35 The best clue to this possibility is when a patient's suffering seems to be excessive or persistent, beyond what would be normal for that condition. In these patients, referral to a psychiatrist or clinical psychologist is a mandatory part of the overall management strategy.

Surgical treatment

Published reports show that about 5% of patients undergoing treatment for temporomandibular disorders require surgery.36 A range of surgical procedures is currently used to treat temporomandibular disorders, ranging from temporomandibular joint arthrocentesis and arthroscopy to the more complex open joint surgical procedures, referred to as arthrotomy.37 Oral and maxillofacial surgeons with a special interest in this area often prefer patients to have undergone a period of non-surgical treatment before seeking a surgical opinion. The benefits and limitations of each of the surgical procedures are readily determined on an individual case basis.3637

Conclusion

The general medical practitioner has an important part to play in the diagnosis and management of patients with temporomandibular disorders since a substantial proportion will attend their general medical practitioner for an initial consultation. General medical practitioners should therefore be familiar with the key features of temporomandibular disorders and be prepared to play a part in managing these patients, especially in the areas of drug treatment and counselling.