Temporomandibular disorders: arthrogenous

Inflammation

Inflammation can originate from TMJ tissues, such as the capsule, medial, and lateral collateral ligaments, TMJ ligament, or posterior attachment. TMJ tissue inflammation can result from blunt trauma and microtrauma that are caused by parafunctional activity. Parafunctional activity is nonfunctional activity, which, when in the orofacial region, includes nail biting, lip or cheek chewing, abnormal posturing of the jaw, and bruxism . Bruxism is diurnal or nocturnal clenching, bracing, gnashing, and grinding of the teeth Inflammation also can result from arthritic conditions.

Physical therapy treatment for TMJ inflammation involves patient education regarding dietary and oral habits . Iontophoresis, phonophoresis, and interferential electric stimulation are therapeutic modalities that are used to decrease TMJ inflammation . Patients who are diagnosed with TMJ inflammation may have altered mandibular dynamics that are due to intracapsular swelling and resultant joint pain. Physical therapists teach patients range of motion exercises that maintain functional mandibular dynamics during the rehabilitation phase without causing more inflammation.

Hypermobility

Hypermobility is excessive translation of the mandibular condyle during opening of the mouth . With condylar hypermobility, the condyle translates anteriorly during opening following the slope of the articular eminence past the articular crest onto the articular tubercle . Hypermobility that occurs unilaterally may be associated with deviation of the mandible, which is observed during mouth opening. Deviation is the mandible moving away from midline, but returning to midline at the end of opening . Although hypermobility may cause disc displacement of the TMJ, the cause and effect relationship has not been established . Hypermobility is a common, and, frequently, benign, condition.

Patients who exhibit hypermobility without pain do not require treatment . Controlling hypermobility is necessary only when other TMJ conditions exist. If the patient has TMJ inflammation, hypermobility may perpetuate the inflammation when the patient opens his/her mouth wide during yawning. In the presence of TMJ inflammation, full mouth opening, regardless of whether hypermobility exists, needs to be avoided.

Dislocation of the condyle can result from uncontrolled hypermobility. Diagnosis of condylar dislocation is made if a patient complains that his or her jaw catches on closing from a full, open mouth position. Hypermobility also may be accompanied by palpable joint noises. Palpable joint noises are noises that are heard by the patient and felt by the clinician while palpating over the TMJ during opening and closing movements of the mandible. Joint noises that are associated with hypermobility need to be differentiated from joint noises that are associated with a disc displacement. Although the patient may not have pain with jaw movement, the experience of joint noise, the feeling of a condyle catching on closing, and an awareness of deviation of the mandible on opening are events that are disconcerting to the patient.

The most important aspect regarding treatment for hypermobility is patient education. Physical therapists should inform their patients that noises and deviations of the jaw are not necessarily signs of significant pathology, and that they can be controlled with proper muscular re-education strategies. When mouth closing is associated with catching, the amount of mouth opening needs to be controlled through neuromuscular coordination exercises that are taught by a physical therapist who is knowledgeable in exercise interventions for TMJ hypermobility .

Disc displacement

Disc displacement can be classified into three stages: disc displacement with reduction, disc displacement without reduction, and chronic disc displacement without reduction . Not all disc displacements are painful or interfere with functional movements of the mandible. Treatment is necessary when a patient experiences pain with or without functional limitations of the jaw . Treatment choices for disc displacements that are painful or interfere with function consist of repositioning the disc to the condyle or allowing the disc to remain displaced while improving the function and decreasing the pain in the intra-articular and associated periarticular/myofascial tissues about the TMJ.

When choosing to reposition the disc to the condyle, the options are arthrotomy or an anterior-repositioning appliance. Because of the progressive nature of disc displacement, which is accompanied by increasing pathologic changes in the disc itself and its peripheral attachments, restoring a satisfactory functional disc–condyle relationship may be difficult . Consequently, arthrotomy and anterior-repositioning appliances have led to mixed results in maintaining a normal long-term disc–condyle relationship .

Arthrotomy is a treatment choice for patients who do not respond to conservative care. Conservative care consists of physical therapy, medication, and a full-coverage acrylic appliance that does not reposition the mandible .

An anterior-repositioning appliance, which repositions the mandible, is the most controversial treatment option for repositioning the disc to the condyle . The controversy relates to whether the anterior-repositioning appliance actually recaptures the disc . During the use of an anterior-repositioning appliance, the absence of joint noises and pain with functional mouth opening does not necessarily indicate that the disc has been recaptured . Studies using pre- and post-CT and well as MRI showed that permanent long-term disc recapture using an anterior-repositioning appliance was noted in only 10% to 30% of the patients . When an anterior-repositioning appliance is discontinued, some patients may require orthodontics and possible orthognathic surgery. For the most part, an anterior-repositioning appliance should be considered on a case-by-case basis, and only should be used as an infrequent treatment option for repositioning disc displacements .

If the choice is not to reposition the disc to the condyle, the treatment options are arthroscopy (in its simplest format involving lavage/lysis), arthrocentesis, and physical therapy. The therapeutic value common to arthroscopy, arthrocentesis, and physical therapy interventions relates to the facilitation of adaptive responses of the articular tissues to the disc displacement. The human TMJ can adapt or remodel in response to articular disc displacement, regardless of the type of intervention, and often best when there is no intervention. For example, the posterior attachment of the disc (superior and inferior stratum and retrodiscal pad) becomes a pseudo disc that can withstand loading of the condyle during function . Restoring a normal disc position is not a necessary component for treating pain and functional resolution . Nonpainful disc displacements are so prevalent in patient and nonpatient populations that they may be considered a normal anatomic variability . Because adaptive responses of the articular tissues within the TMJ are common secondary to disc displacement—and in most cases lead to pain-free and functional outcomes—perhaps the most therapeutic intervention should be the least invasive (ie, physical therapy).

Disc displacement without reduction

An article that has reviewed the literature comparing arthrocentesis, arthroscopic surgery, and physical therapy for the treatment of disc displacement without reduction has demonstrated no significant difference in the effects of maximum mandibular opening, pain intensity, or mandibular function . The decision to perform arthroscopy or arthrocentesis instead of physical therapy should be based upon an evidence-based evaluation as well as the needs of the informed patient. When noninvasive treatment is recommended, physical therapy that is performed by a licensed physical therapist with an orthopedic specialty—and preferably a subspecialty in TMDs—should be the first choice in the treatment of disc displacements without reduction.

Physical therapy procedures may be successful in the treatment of pain and limited mouth opening that are associated with disc displacement without reduction . Using various active and passive jaw exercises, as well as intraoral mobilization techniques, physical therapists may restore functional mandibular dynamics without pain when the disc is displaced. Inflammation that results from the disc displacement or that coexists with the disc displacement may be treated as identified previously. An oral appliance that is fabricated by a dentist also may facilitate the reduction of inflammation, especially if the patient bruxes. If physical therapy and the use of an oral appliance have not reduced pain to a satisfactory level or regained functional movements of the jaw after 4 to 12 weeks, the patient should consult with an oral surgeon to discuss surgical options.

Disc displacement with reduction and chronic disc displacement without reduction

Patients who experience a disc displacement with reduction or a chronic disc displacement without reduction may have functional movements of the mandible without pain . The first goal of physical therapy consists of educating the patient on the cause of his or her joint noises (ie, reciprocal click or crepitus), so that he or she is aware of the aggravating factors of the condition. If the patient has TMJ pain that is due to inflammation, the goal of physical therapy is to reduce pain and improve mandibular function through manual therapy and exercise interventions, despite the disc displacement. An oral appliance that is fabricated by a dentist also may facilitate the reduction of inflammation, especially if the patient bruxes. A patient who has joint inflammation that does not respond to an oral appliance or 4 to 12 weeks of physical therapy may be referred to an oral surgeon to discuss surgical options.

A physical therapist may attempt to eliminate or decrease joint noises that are associated with a disc displacement with reduction. Clinically, the goal of physical therapy treatment is to have functional mandibular dynamics without pain and without noises, despite the disc being displaced permanently. The following criteria are used for patient selection:

• Joint noises are disturbing to the patient

• Patient experiences intermittent catching/locking with or without pain during mouth opening

• Patient understands that the treatment may (a) cause joint pain or (b) cause limited mouth opening, or (c) result in having TMJ surgery because (a) or (b) could not be resolved.

• Patient has consulted with a dentist or oral surgeon previously

Exercises and intraoral manual procedures for treating a reducing disc are not the same as exercises and intraoral manual procedures for increasing limited mouth opening that is associated with a nonreducing disc and fibrous adhesions. Progressing a reducing disc to a nonreducing disc involves the application of exercises and intraoral manual procedures that prevent the disc from reducing on opening. Preventing the disc from reducing on opening elongates the posterior attachment. Once sufficient elongation of the posterior attachment occurs, the patient can achieve functional opening without popping with the disc remaining displaced . The patient may go through a short period with limited opening and possible pain. In the author’s experience, 4 to 12 weeks is a sufficient time to achieve functional mandibular dynamics without pain and with an absence of joint noises with the disc displaced permanently.

Fibrous adhesions

Fibrous adhesions may appear in the capsular-ligament tissues and in the upper joint space of the TMJ . Fibrous adhesions can result from chronic inflammation, blunt trauma, postoperative healing of a capsular incision, or immobility that occurs with intermaxillary fixation or from limited opening that is associated with a disc displacement without reduction. The physiologic changes that are associated with fibrous adhesions are documented in the literature . Physical therapy procedures and modalities for the treatment of fibrous adhesions are similar, but not identical, to those that are used for treating a disc displacement without reduction. Treating fibrous adhesions involves applying an intraoral mobilization technique that is referred to as “lateral glide.” A lateral glide passive intraoral mobilization procedure may be performed at the same time that the patient opens his or her mouth actively. Clinically, this passive/active mobilization force targets the restrictions in the lateral aspect of the capsular–ligament complex of the TMJ. The clinical decisions that are necessary to determine the duration, intensity, frequency, and progression of exercise intervention strategies require skill and experience. The effectiveness of a mobilization technique is related to proper patient selection, appropriate choice of technique, effective execution of the procedure, and making adjustments that are based on tissue response and patient feedback. Inappropriate management of a mechanical dysfunction of the TMJ by untrained personnel may lead to an exacerbation of symptoms and a worsening of the condition.

Temporomandibular disorders: myogenous

Masticatory muscle pain

Masticatory muscle pain is a common clinical finding in patients who experience head and orofacial pain . The relationship between bruxism and masticatory pain is unclear ; however, parafunctional activity, such as bruxism, may be a predisposing, precipitating, or perpetuating factor of masticatory muscle pain . The common treatment for managing bruxism/masticatory pain is an oral appliance . Oral appliances have been shown to be effective in the treatment of masticatory pain .

Physical therapists may provide treatments that offer symptomatic relief in masticatory muscle pain through modalities and therapeutic procedures. Modalities, such as iontophoresis, ultrasound, and electric muscle stimulation, may help to reduce muscle pain . Intraoral and extraoral soft tissue mobilization to the muscles of mastication also may provide symptomatic relief . Therapeutic exercises to the mandible that consist of isometric, isotonic, and eccentric contraction have been observed clinically to reduce masticatory muscle pain . Patient education strategies that are related to oral modifications and enhancing self-awareness about aggravating factors also have been shown to provide relief in masticatory muscle pain . Oral modifications consist of diet changes as well as eliminating or limiting oral habits, such as gum chewing and nail, lip, or cheek biting. Self-awareness strategies also include instructing the patient on the proper rest position of the tongue and mandible. Patients who take an active role in making oral modifications and performing neuromuscular exercises may achieve satisfactory daytime relief from masticatory muscle pain. Decreasing the cumulative loading during the day also may provide relief in nighttime pain that is associated with bruxism. Nocturnal bruxism is more difficult to treat, even when the patient wears an oral appliance. Physical therapists can assist in reducing nocturnal bruxism by addressing head and neck positioning while sleeping. Instructing the patient on proper selection and usage of pillow support that is appropriate for their cervical spine alignment and motion function may help to lessen the tendency for bruxism at night by enabling a more restful mandibular position. Cervical spine disorders that may contribute to bruxism are covered in a later section.