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 systematically examined. The muscles
should be palpated for the presence of tenderness, fasciculations, spasm, or trigger points . The TMJs are examined for tenderness and noise
The location of the joint tenderness (e.g., lateral,
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., multiple 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 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
Radiographs of the TMJ are extremely helpful in the diagnosis
of intraarticular, osseous, and soft tissue pathology.
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
are available that may provide useful information in certain cases.
Transcranial radiographs. A standard dental radiographic
unit combined with a head-holding device can be used to produce a transcranial image of the TMJ.
Although this view will not allow detailed examination of all aspects of the TMJ, excellent evaluation of the lateral pole of the condyle can be accomplished when the proper radiographic technique is used. Because bony
pathology of the TMJ frequently extends to the lateral pole, this technique can be helpful in diagnosing bony internal joint pathology .
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 of view of the TMJ, this can frequently provide a good assessment of the bony anatomy of the articulating surfaces of the mandibular condyle and glenoid fossa , 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 both the open and closed position.
Tomograms. The tomographic technique allows more detailed view of the TMJ.2 This technique allows radiographic sectioning of the joint at different levels of the condyle and fossa complex, which provides individual
views visualizing the joint in "slices" from the medial tothe lateral pole. These views eliminate bony superimposition and overlap and provide a relatively clear picture of the bony anatomy of the joint.
Temporomandibular joint arthrography. This
imaging method was the first technique available that
allowed visualization (indirect) of the intraarticular disk. Arthrography involves the injection of contrast material into the inferior or superior spaces of a joint, after
which the joint is radiographed.-3 Evaluation of the configuration
of the dye in the joint spaces allows evaluation of the position and morphology of the articular disk . This technique also demonstrates the presence of perforations and adhesions of the disk or its attachments.
With the availability of more advanced, less invasive techniques arthrography is rarely used.
Computed tomography. Computed tomography (CT) provides a combination of tomographic views of the joint, combined with computer enhancement of hard
and soft tissue images.4 This technique allows evaluation of a variety of hard and soft tissue pathology in the joint CT images provide the most accurate radiographic assessment of the bony components of the joint . CT
scan reconstruction capabilities allow images obtained in one plane of space to be reconstructed so that the image 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.
Magnetic resonance imaging. The most effective
diagnostic imaging technique to evaluate TMJ soft tissuesm is magnetic resonance imaging (MRI) 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
anatomical components of the joint during function. The fact that this technique does not use ionizing radiation is a significant advantage.
Nuclear imaging. This technique involves injection
of Tc", a gamma-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 computerized tomography (SPECT) images can then be used to determine active areas of bone metabolism.Although this technique is extremely sensitive, the information obtained may be somewhat 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
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.7 To evaluate possible behavioral changes associated with pain and dysfunction, the history should
include questions regarding functional limitation that results from the patient s symptoms. If the functional limitation appears to be excessive when compared with
the patient s clinical signs or the patient appears to be clinically depressed, further psychologic evaluation may be warranted.8
CLASSIFICATION OF TEMPOROMANDIBULAR
Myofascial Pain :Myofasdal 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. This abnormal muscular function is frequently but not always associated with daytime clenching or nocturnal bruxism. The cause of MPD is controversial,although it is
generally considered to be multifactorial.9 One of the
most commonly accepted causes of MPD is bruxism secondary
to stress and anxiety, with occlusion being a modifying
or aggravating factor. MPD may also occur secondary to 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 hitemporal 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
Disk Displacement Disorder
In a normally functioning TMJ the condyle functions in
both 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 . During function the biconcave disk remains interpositioned between the condyle and fossa, with the condyle remaining against the thin intermediate zone during all phases of opening and closing.
Anterior disk displacement with reduction.
In anteriordisk displacement the disk is positioned anterior and medial to the condyle in the closed position. During opening the condyle moves over the posterior band of
the disk and eventually returns to the normal condyle
and disk relationship, resting on the thin intermediate zone. During closing the condyle then slips posteriorly
and rests on the retrodiscal tissue, with the disk returning
to the anterior, medially displaced position Examination of the patient usually reveals joint tenderness, and muscle tenderness may also exist. Jointnoise (i.e., clicking) is commonly heard with opening,
when the condyle moves from the area posterior to the
disk into the thin concave area in the middle of the disk. In some cases clicking can be heard or palpated during the closing cycle. Maximal opening can be normal or slightly limited, with the click occurring during the opening movement. Anatomically the opening click corresponds to the disk reducing to a more normal position.
The closing click (i.e., reciprocal click) corresponds to the disk failing to maintain its normal position between the condylar head and the articular eminence and slipping forward to the anteriorly displaced position. Crepitus may be present and is usually a result of articular movement
across irregular surfaces. The images obtained from plain TMJ radiography in patients with anterior disk displacement may be normal or may demonstrate slight bone abnormalities. MRI images usually demonstrate anterior displacement of the disk.
Anterior disk displacement without reduction. In this type of internal derangement the disk displacement cannot be reduced, and thus the condyle is unable to translate to its full anterior extent, which prevents maximal opening and causes deviation of the mandible to the
In these patients no clicking occurs, because they are
unable to translate the condyle over the posterior aspect of the disk. This lack of translation may result in restricted opening, deviation to the affected side, and decreased lateral excursions to the contralateral side. Some evidence suggests that the limitation of motion may not be directly
related to the actual displacement of the disk but rather
to the adherence of the disk to the fossa, causing a restriction
of the sliding function of the joint.10 Radiographic evaluation of disk displacement without reduction is similar to findings in anterior disk displacement
with reduction. Plain TMJ radiography may appear normal, whereas CT scans and MRIs generally demonstrate anteromedial disk displacement. However, in this disorder, images taken in the maximal open position continue to show anterior disk displacement within the open position.
Degenerative Joint Disease (Arthrosis,
DJD includes a variety of anatomic findings, including
irregular, perforated, or severely damaged disks in association with articular surface abnormalities, such as articular surface flattening, erosions, or osteophyte formation . The mechanisms of TMJ degenerative diseases are not clearly understood but are thought to be multifactorial. Current concepts of DJD incorporate three possible mechanisms of injury: (1) direct mechanical trauma, (2) hypoxia
reperfusion injury, and (3) neurogenic inflammation Mechanical trauma may be a result of significant and obvious trauma to the joint or much less obvious microtrauma, such as excessive mechanical loading. The excessive stress produced in the joint can lead to molecular disruption
and the generation of free radicals, with resulting oxidative stress and intracellular damage. Excess loading can also affect local cell populations and reduce the reparative capacity of the joint. The hypoxia-reperfusion theory suggests that excessive intracapsular hydrostatic pressure within the TMJ may exceed the blood vessel perfusion pressure, resultingin hypoxia. clearly demonstrated in patients during clenching and bruxing.12 When the pressure in the joint is decreased and
perfusion is reestablished, free radicals are formed. These free radicals may interact with other substances in the joint (e.g., hemoglobin) to produce even more damage .Neurogenic inflammation results when a variety of substances are released from peripheral neurons. It is
hypothesized that in cases of disk displacement the compression
or stretching of the nerve-rich retrodiscal tissue
may result in release of proinflammatory neuropeptides.
11 13 The release of cytokines results in the release
and activation of a variety of substances including prostaglandins, leukotrienes, and matrix-degrading enzymes. These compounds not only have a role in the disease process but also may serve as biologic markers that may help to diagnose and eventually treat joint pathology.14 15
It must be emphasized that it is impossible to predict the
progression of joint pathology.. Patients with DJD frequently experience pain associated with clicking or crepitus, located directly over the TMJ.
Usually, an obvious limitation of opening is present, and symptoms usually increase with function. Radiographic findings are variable but generally exhibit decreased joint space, surface erosions, osteophytes, and flattening of the condylar head. Irregularities in the fossa and articular eminence may also be present.
Systemic Arthritic Conditions
A variety of systemic arthritic conditions are known to
affect the TMJ. The most common of these is rheumatoid
arthritis. Other processes, such as systemic lupus, can also affect the TMJ. In these cases symptoms are rarely isolated to the TMJs, and several other signs and symptoms of arthritis are usually present in other areas of the body. In the case of rheumatoid arthritis, an inflammatory process results in abnormal proliferation of synovial tissue in a so-called pannus formation.
Chronic Recurrent Dislocation
Dislocation of the TMJ occurs frequently and is caused by
mandibular hypermobility. Subluxation is a displacement
of the condyle, which is self-reducing and generally requires no medical management. A more serious condition occurs when the mandibular condyle translates anteriorly in front of the articular eminence and becomes locked in that position . Dislocation may be
unilateral or bilateral and may occur spontaneously after opening the mouth widely, such as when yawning, eating, or during a dental procedure. Dislocation of the mandibular condyle that persists for more than a few seconds generally becomes painful and is often associated
with severe muscular spasms. Dislocations should be reduced as soon as possible. This reduction is accomplished by applying downward
pressure on the posterior teeth and upward pressure on the chin, accompanied by posterior displacement of the mandible. Usually reduction is not difficult. However, muscular spasms may prevent simple reduction, particularly when the dislocation cannot be reduced immediately. In these cases, anesthesia of the auricular temporal
nerve and the muscles of mastication may be necessary.
Sedation to reduce patient anxiety and provide muscular
relaxation may also be required. After reduction the
patient should be instructed to restrict mandibular opening
for 2 to 4 weeks. Moist heat and nonsteriodal antiinflammatory
drugs (NSAIDs) are also helpful in controlling
pain and inflammation.
Intracapsular ankylosis. Intracapsular ankylosis, or fusion of the joint, leads to reduced mandibular opening that ranges from partial reduction in function to complete immobility of the jaw. Intracapsular ankylosis
results from a fusion of the condyle, disk, and fossa complex, as a result of the formation of fibrous tissue, bone fusion, or a combination of the two. The most common cause of ankylosis involves macrotrauma,
most frequently associated with condylar fractures. Other causes of ankylosis include previous surgical treatment that resulted in scarring and, in very rare cases, infections.
Evaluation of the patient reveals severe restriction of
maximal opening, deviation to the affected side, and
decreased lateral excursions to the contralateral side. If
the ankylosis is the result primarily of fibrous tissue, jaw
mobility will be greater than if the ankylosis is a result of
Extracapsular ankylosis. This type of ankylosis usually
involves the coronoid process and temporalis muscle.
Frequent causes of extracapsular ankylosis are coronoid process enlargement, or hyperplasia, and trauma to the zygomatic arch area. Infection around the temporalis muscle may also produce extracapsular ankylosis. Patients initially have limitation of opening and deviation to the affected side. In these cases, complete restriction of opening is extremely rare, and limited lateral and protrusive movements can usually be performed indicating no intracapsular ankylosis.
Neoplasms in the TMJ are extremely rare. They can occasionally
result in restriction of opening and joint pain.
Tumors within the TMJ may result in an abnormal
condyle and fossa relationship or an intracapsular ankylosis.
A complete discussion of the neoplastic processes
known to occur in the TMJ area is beyond the scope of
Infections in the TMJ area are extremely rare, even in the
case of trauma or surgical intervention in this area. In
third world countries where antibiotic therapy of middle
ear infections is not available, extension of infectious
processes may occasionally involve the TMJ and result in
Four types of medication have been widely used in the
treatment of temporomandibular disorders: (1) NSAlDs, (2) occasional use of stronger analgesics, (3) muscular
relaxants, and (4) tricyclic antidepressants.
NSAIDs not only reduce inflammation but also serve as an excellent analgesic. Some examples of NSAIDs are naproxen (Naprosyn), ibuprofen (Motrin), diflunisal (Dolobid), and piroxicam (Feldene). These medications can be effective in reducing inflammation in both muscles and joints and in most cases provide satisfactory pain
relief. These drugs are not associated with severe addiction problems, and their use as an analgesic is strongly preferred over narcotic medications. It is important to remember that these medications work best when administered on a timetable rather than on a pain-dependent
schedule. Patients should be instructed to take the medicine
on a regular basis, obtaining an adequate blood level
that should then be maintained for a minimum of 7 to 10
days. Discontinuation or tapering of the medicine can then be attempted.
The COX-2 inhibitors such as celecoxib (Celebrex) and
rofecoxib (Vioxx) have gained popularity in the treatment of inflammation and pain. Prostaglandins produced
by COX-1 activity appear to be required for normal
physiologic function, whereas those produced by COX-2 activation mediate pain and inflammation. The COX-2 inhibitors are intended to reduce pain and inflammation without affecting prostaglandin-dependent functions. These drugs have been associated with significant side
effects, including gastric and cardiac complications. Analgesic medicines for TMJ patients may range from acetaminophen to potent narcotics. One important principle
of treatment for all pain and dysfunction patients is to remember that the problem may be chronic and that medication could produce long-term addiction. Because
of the sedative and depressive effects of narcotics and
their potential for addiction, these medications should be restricted to short-term use in patients with severe, acute pain. In such instances medications such as acetaminophen
with codeine should be sufficient. This medication
should not be used for longer than 10 days to 2 weeks.
Muscle relaxants may provide significant improvement
in jaw function and relief of masticatory pain. However,
muscle relaxants have a significant potential for depression
and sedation and can produce long-term addiction.
In many patients with acute pain or exacerbation of muscular hyperactivity, muscle relaxants can be considered for short periods, such as 10 days to 2 weeks. The lowest effective
dose should be used. Diazepam (Valium) 2 to 5 mg or cyclobenzaprine (Flexeril) 10 mg generally provides adequate
relief of muscular symptoms in patients with TMD. Tricyclic antidepressants in low doses appear to be useful in the management of patients with chronic pain. Tricyclic antidepressants prevent the reuptake of amine neurotransmitters, such as serotonin and norepinephrine,
causing an inhibition of pain transmission. Recently,
anecdotal evidence has suggested that these antidepressants
may be effective in decreasing nocturnal bruxism.
It appears that nighttime bruxing may be in part a
result of disruption of normal sleep patterns. The use of
amitriptyline (Elavil) in small doses (10 to 25 mg at bedtime)
may improve sleep patterns, decrease bruxism, and
result in decreased joint and muscle pain . Medications that must be administered by injection may occasionally be helpful in managing muscular and joint pain and inflammation. Recently the use of Botulinum Toxin A has shown promise in decreasing masticatory muscle hyperactivity.18 19 Botulinum Toxin (Botox) is a neurotoxin produced by the bacterium Clostridium botulinum. This neurotoxin produces a paralytic effect on muscles by inhibiting the release of acetylcholine at the neuromuscular junction. In very low doses, Botox can be safely administered by injection directly into the affected muscle area, decreasing muscle contraction activity and the associated pain. The effect of Botox is temporary.
Physical therapy can be extremely useful in the management of patients with temporomandibular pain and dysfunction. The most common modalities used include EMG biofeedback and relaxation training, ultrasound, spray and stretch, and pressure massage. Relaxation training, although perhaps not physical therapy in the strictest sense, can be extremely effective in reducing symptoms caused by muscular pain and
hyperactivity. During the educational phase, patients are made aware of the contribution of stress and muscular hyperactivity to pain. Relaxation techniques can be used to reduce the effects of stress on muscle and joint pain. EMG monitoring of the patient s muscular activity can be
used as an effective teaching tool by providing instant
feedback demonstrating relaxation therapy, reduction of muscular hyperactivity, and the resultant improvement in symptoms of pain.
Ultrasound is an effective way to produce tissue heating
with the use of ultrasonic waves, which alter blood flow and metabolic activity at a deeper level than that provided by simple surface moist-heat applications.22 The effect of ultrasonic tissue heating is theoretically related to increase in tissue temperature, increase in circulation,
increase in uptake of painful metabolic by-products, and
disruption of collagen cross-iinking, which may affect adhesion formation. All of these effects may result in a more comfortable manipulation of muscles and a wider
range of motion. In addition, intraarticular inflammation may also be reduced with ultrasonic applications. Ultrasonic treatments are usually provided by a physical therapist
in combination with other treatment modalities. The typical routine for application of ultrasound is the
use of 0.7 to 1.0 watts per cm2 applied for approximately10 minutes over the affected areas (i.e., temporalis and masseter muscles and TMJ) . Ultrasonic treatments are most effective when repeated every other day or every third day for several consecutive treatments. Spray and stretch is an effective method for improving range of motion. The theory behind spray and stretch is the concept that stimulating large cutaneous nerve fibers can produce an overriding or distracting effect on pain
input from smaller fibers that originate in the muscles
and joints.23 By spraying a vapocoolant material, such as fluormethane, over the lateral surface of the face, the muscles of mastication can be passively or actively stretched with a reduced level of pain . Friction massage involves the use of firm cutaneous
pressure sufficient to produce a temporary degree of ischemia. This ischemia and the resultant hyperemia have been described as a method for inactivation of trigger points, which are areas responsible for pain referred to muscles in the head and neck area.23 More frequently this technique may be useful in disrupting small fibrous connective
tissue adhesions that may develop within the muscles during healing after surgery and injury or as a result of
prolonged muscular shortening from restricted motion. Physical therapists and other practitioners sometimes
use transcutaneous electronic nerve stimulation (TENS) to provide pain relief for chronic pain patients when
other techniques have been unable to eliminate or reduce pain symptoms . The exact mechanism of action of TENS is not completely
understood. The technique was initially based on the concept that stimulation of superficial nerve fiber with TENS may be responsible for overriding pain input from structures such as masticatory muscles and the TMJs. Interestingly, many patients who use TENS units experience
pain relief that is longer in duration than the time during which the unit is actually applied. This may be a result of the release of endogenous endorphin compounds that can provide extended periods of decreased pain. Each of the physical therapy modalities may be extremely useful in initial attempts to reduce TMJ pain and increase range of motion. The low cost of physical therapy compared with other medical treatment, the likelihood that some benefit will occur, and the minimal risk
associated with these techniques are strong arguments for frequent use of physical therapy in the management of patients with TMD.
Occlusal splints are generally considered a part of the reversible or conservative treatment phase in the management of TMD patients. Splint designs vary; however, most splints can be classified into two distinct groups: (1) autorepositioning splints and (2) anterior repositioning
Autorepositioning splints. The autorepositioning splints, also called anterior guidance splints, superior repositioning splints, or muscle splints, are most frequently used to treat muscle problems or eliminate TMJ pain when no specific internal derangement or other obvious pathology can be identified. However, these splints may be used
in some cases, such as anterior disk displacement or DJD, in an attempt to unload or reduce the force placed directiy on the TMJ area. Nitzan has shown that properly designed splints can be effective in reducing intraarticular pressure.12 The splint is usually designed to provide
full-arch contact without working or balancing interferences
and without ramps or deep interdigitation, which would force the mandible to function in one specific
occlusal position . This splint allows the patient to seek a comfortable muscle and joint position without excessive influence of the occlusion. An example of this type of splint would be in a patient with a
class II malocclusion and significant overjet who continually postures forward to obtain incisor contact during mastication. Many of these patients complain of muscular symptoms and describe a feeling that they do not have a consistent, repeatable bite relationship. Wearing an autorepositioning splint allows full-arch dental contact with the condyles in a more posterior retruded position, which frequently results in reduction in muscle and joint symptoms.
Anterior repositioning splints. Anterior repositioning splints are constructed so that an anterior ramping effect forces the mandible to function in a protruded
position . This type of splint is most useful in
providing temporary relief and, in rare cases, a long-termcure for anterior disk displacement with reduction. In these cases the anterior position is determined by protrusion of the mandible necessary to produce the proper disk
and condyle relationships (after the protruding or opening click has occurred). The splint is usually worn 24 hours a day for several months. Theoretically after the disk is repositioned for a long period, the posterior ligaments may shorten and
maintain the disk in proper relationship to the condyle. Despite theoretical expectations, these splints are generally ineffective in producing permanent reduction of disk displacement. However, even when the splints are not
curative, they often provide significant relief of discomfort in the acute stages of TMJ dysfunction.
PERMANENT OCCLUSION MODIFICATION
After completion of a course of reversible treatment, many patients may be candidates for permanent modification
of the occlusion. This permanent modification
appears to be most appropriate when patients have had significant improvement in masticatory function and
reduction in pain as a result of temporary alteration of occlusal position with splint therapy. Permanent occlusion modification may include occlusal equilibration,
prosthetic restoration, orthodontics, and orthognathic surgery. Although the relationship between occlusion abnormalities and TMD is unclear, it does appear that permanent modification of the occlusion in indicated patients may provide long-term improvement in symptoms of pain and dysfunction.
Despite the fact that many patients with internal joint pathology will improve with reversible nonsurgical treatment, some patients will eventually require surgical intervention to improve masticatory function and decrease pain. Several techniques are currently available for correction of a variety of TMj derangements.
Arthrocentesis involves placing needles into the TMJ and therefore is not actually a surgical procedure. However, because it is somewhat invasive and generally performed by oral and maxillofacial surgeons, it is discusse here. Most patients undergoing arthrocentesis do so with
local anesthesia and intravenous (IV) sedation. Several techniques have been described for TMJ arthrocentesis. The most common method involves initially placing one needle into the superior joint space. A small
amount of lactated Ringer s solution is injected to distend the joint space and can then be withdrawn and evaluated for diagnostic purposes, if desired. The joint is redistended, and a second needle is placed into the superior
joint space. This allows larger amounts of fluid (approximately 200 ml) to lavage the joint. During the arthrocentesis the jaw can be gently
manipulated. At the conclusion of the procedure, steroids, local anesthesia, or a combination of both can be injected into the joint space before the needles are
withdrawn. Discomfort after the procedure is managed with mild analgesics or NSAIDs. Some type of exercise regimen or physical therapy is accomplished during the recovery period. Many types of internal joint pathology appear to
respond well to arthrocentesis. The most common use appears to be in patients with anterior disk displacement without reduction. Treatment appears to be very effective, with results similar to or better than other types of
arthroscopic and open surgical procedures. Nitzan demonstrated that arthrocentesis produced significant improvement in incisal opening and reduction of pain in patients with persistent and severe closed lock.24 The success seen with arthrocentesis has several potential explanations. When disk displacement occurs, negative pressure may develop within the joint, causing a "suction cup" effect between the disk and fossa. Distending the joint obviously eliminates the negative pressure. In some cases of more chronic disk displacement, some
adhesion may develop between the disk and fossa. With arthrocentesis the distension under pressure can release these adhesions. Capsular constriction may occur as a result of joint hypomobility and can be stretched with
pressure distension. Finally, there may be an accumulation of some of the chemical mediators described previously. The simple flushing action in the joint may eliminate or decrease biochemical factors contributing to inflammation and pain.
Arthroscopic surgery has become one of the most popular and effective methods of diagnosing and treating TMJ disorders.25 This technique involves placement of a small cannuia into the superior joint space. An arthroscope with light source is then inserted through the cannula into the superior joint space . The arthroscope
is then connected to a video camera and monitor, which allow excellent visualization of all aspects of the glenoid fossa and superior aspect of the disk.
techniques are limited primarily to visualization of the joint for diagnostic purposes and lysis of fibrous joint adhesions, combined with lavage of the joint.
More sophisticated arthroscopic operative techniques have been developed, increasing the ability of the surgeon to correct a variety of intracapsular disorders. Current surgical techniques usually involve the placement
of at least two cannulas into the superior joint space. One cannula is used for visualization of the procedure with the arthroscope, while instruments are placed
through the other cannula to allow instrumentation in the joint . Instrumentation used through the arthroscope includes forceps, scissors, sutures, medication needles, cautery probes, and motorized instrumentation, such as burs and shavers. Laser fibers can also be used to eliminate adhesions and inflamed
tissue and incise tissue within the joint. Disk manipulation, disk attachment release, posterior band cautery, and suture techniques have been developed in
an attempt to reposition or stabilize displaced disks.26 Although it appears that attempts to reposition displaced disks do not result in anatomic restoration of normal disk position, patients undergoing this type of treatment
appear to have significant clinical improvement after arthroscopic surgery.
Arthroscopic surgery has been advocated for treatment of a variety of TMJ disorders, including internal derangements, hypomobility as a result of fibrosis or
adhesions, DJD, and hypermobility. The efficacy of arthroscopic treatment appears to be very similar to that of open joint procedures, with the advantage of less surgical morbidity and fewer and less severe complications.
Disk Repair or Removal
In some cases the disk is so severely damaged that the remnants of disk tissue must be removed. Diskectomy without replacement was one or the earliest surgical
procedures described for treatment of severe TMJ internal derangements.30 With current technology, the diskectomy procedure can be performed through arthroscopic techniques described earlier. Although this technique
has been widely used, there seems to be a wide variation in clinical results, with some joints showing minimal anatomic changes and significant clinical improvement to joints that demonstrate severe degenerative changes with continued symptoms of pain and dysfunction.