TMJ DISORDERS

GUIDE: DR. SANJEEV KUMAR (PROF & HEAD) PRESTED BY: UDAY KAKADIA

CLASSIFICATION SYSTEM:

1. Masticatory muscle disorders

- Protective co-contraction- Local muscle soreness- Myospasm- Myofascial pain

2. TMJ disorders

a. Derangement of condyle-disc complexA. Disc displacemetB. Disc dislocation with reductionC. Disc dislocation without reduction

b. Structural inciompatibility of articular surfacesA. Deviation in formB. Adherence & adhesionsC. SubluxationD. Spontaneous dislocation

c. Inflammatory disorders of TMJA. Synovitis & capsulitisB. RetrodiscitisC. Arthritis

- Osteoarthritis- Osteoarthrosis- Polyarthritis

d. Inflammatory disorder of associated structureA. Temporal tendonitisB. Stylomandibular ligament inflammation

3. Chronic mandibular hypomobility

a. Ankylosis

b. Muscle contracture- Myostatic

- Myofibrotic c. Coronal impadance

4. Growth disorders

- Aplasia - Hypoplasia- Hyperplasia

5. TMJ tumors

a. Benign tumors- Chondroblastoma- Chondroma- Fibrous dysplasia- Giant cell tumor- Hemangioma- Osteochondroma & Osteoma

b. Malignant tumors- Chondrosarcoma- Multiple myeloma- Osteosarcoma- Synovial sarcoma

MASTICATORY MUSCLE DISORDERS:

1. Protective co-contraction:-

It is the initial response of a muscle to altered sensory or proprioceptive input or injury, also called protective muscle splinting or co-activation.

Altered sensory input → antagonist muscle group seem to fire during movement → attempt to protect the injured part. It is not a pathologic condition.

CAUSE:-

- Altered sensory or proprioceptive input.- Presence of constant deep pain input.- ↑ Emotional stress.

HISTORY: - It remains a few days. If not resolved, local muscle soreness is likely follows;

- A recent alteration in local structure.- A recent source of constant deep pain.- A recent ↑ in stress.

CLINICAL FEATURES:-

↓ Movement but can achieve a relatively normal range when requested to do so. Minimal pain at rest, ↑ pain to function, feeling of muscle weakness.

DEFINITIVE TREATMENT:-

Normal CNS response, so treatment is not indicated. Treatment is directed towards reason of co-contraction.

Poorly fitting restoration – Altering the restoration

Deep pain – pain to be addressed appropriately.

SUPPORTIVE THERAPY:-

Instructing the pt to restrict the use of mandible within painless limit. Soft diet, short term pain medication. Muscle exercises & physiotherapy contraindicated.

2. LOCAL MUSCLE SORENESS:-

It is primary non-0inflammatory myogenous pain disorder. It is first response of muscle to continued co-contraction.

CAUSE:-

Protective co-contraction secondary to a recent alteration in local structure.

Local tissue trauma of unaccustomed use of muscle.

↑ stress.

HISTORY:-

Pain begin several hours after event asso, with protective co-contraction.

Pain begin asso. with tissue injury (injection, opening widely)

Pain begin secondary to another source of deep pain. ↑ stress.

CLINICAL FEATURES:-

↓ velocity & range of movement. Minimum pain at rest which ↑with function. Actual muscle weakness. Local tenderness when involved muscle is palpated.

DEFINITIVE TREATMENT:- Primary goal : ↓ sensory input should be eliminated.

Any altered sensory input should be eliminated. Any source of deep pain is eliminated. Restricted mandibular use within painless limit.

↓ non functional teeth contact, occlusal appliance at night for bruxism.

SUPPORTIVE THERAPY:-

NSAIDs, manual physical therapy – passive muscle stretching & gentle massage. Relaxation therapy also helpful.

3. MYOSPASM:-

An involuntary CNS induced tonic muscle contraction often asso. with local metabolic condition within muscle tissue.

CAUSE:-

Continued deep pain input.

Local metabolic factors within muscle tisslue asso. with fatigue or overuse.

Idiopathic myospasm mechanics.

HISTORY:- A sudden onset of restricted jaw movement accompanied by muscle rigidity.

CLINICAL FEATURES:-

Marked restriction in range of movement according to muscle involved, acute malocclusion. Pain at rest which ↑ with function.

Affected muscle is firm & painful to palpation with gen. muscle tightness.

DEFINITIVE TREATMENT:-

- Reduction of spasm itself.- Addresses the cause.

Reducing the pain & passively lengthening/stretching of involved muscle. Reduction of pain with manual massage, coolant spray, ice or injection of LA into muscle. Once pain is reduced, muscle is passively stretch to full length.

When obvious cause is present, eliminate it. If secondary to fatigue/overuse, rest is advised.

SUPPORTIVE THERAPY:- Physical therapy

4. MYOFASCIAL PAIN:-

Referred from a localized tender area, a trigger point, is a taut band of skeletal muscle. Any skeletal muscle of body including masticatory muscle. head and neck, shoulder & lower back is most involved.

Area to which pain is referred – ‘Zone of referrance’

Occurs due to acute injury or frequently overuse and chronic micortrauma.

Travel in 1940s first theorized that skeletal muscle is spasm could be source of pain. Schwatz postulated the TMJ pain dysfunction syndrome. He was first to implicate psychologic makeup as predisposing factor.

In 1969, Laskin gave more comprehensive explanation of the problem. Stress was the significant cause of clinching & grinding habits which cause spasm of the muscle. occlusal abnormalities also has secondary role in etiology.

SIGNS & SYMPTOMS:-

Unilateral dull pain in ear or preauricular region that is commonly worse on awaking. Tenderness of one or more muscle of mastication, on palpation. Limitation or deviation of mandible on opening.

Degenerative changes in TMJ if become chronic. Irregularity in occlusion → Precipitating factor → Occlusal interfere post. Bite collapse & deep overbite – overjet.

Overuse of muscle, general sign of bruxism, tooth wear, mobility, thickening of PDL, hyperactivity of muscle of mastication.

INITIAL TREATMENT:-

1. EDUCATION: Explanation of diagnosis & treatment. Reassurance about good prognosis for recovery & natural course. Explanation of doctor’s & pt’s role in therapy. Information to enable pt to perform self care.

2. SELF CARE: Eliminate oral habits (clinching, chewing), provide information on jaw care asso. with daily activity.

3. PHYSICAL THERAPY: Education regarding biomechanics of jaw, neck & head posture. Passive modalities (Heat & cold therapy, ultrasound, TENS), range of motion exercises (Active & passive), posture therapy, passive stretching, general exercises, conditioning programme.

4. INTRAORAL APPLIANCE: Cover all teeth in arch the appliance is seated on. Adjust to achieve simultaneous contact. Adjust stable, comfortable mandibular posture. Avoid long term use.

5. PHARMACOTHERAPY: NSAIDs, acetoaminophen, muscle relaxants, antianxiety agents.

6. BEHAVIORAL/RELAXATION TECHNIQUES: relaxation therapy, hypnosis, biofeedback, cognitive behavioral therapy.

7. TRIGGER POINT THERAPY: Cooling of skin (Flomethane) & stratching, injection of LA, saline or sterile water (procaine diluting with 0.5% saline – low toxicity).

- Spray & stretch therapy – 3-5 weekly sessions.

INFLAMMATORY JOINT DISORDER

Characterized by deep pain usually accentuated by function.

1. SYNOVITIS & CAPSULITIS:-

An inflammation of synovial tissue or capsular ligament which differentiate only by arthroscopy.

CAUSE:- Followed by trauma to tissue (Microtrauma & macrotrauma) or inflammation from adjacent tissue.

HISTORY:- Incidence of trauma or abuse. Continuous pain originates in the joint area & with movement it increases.

CLINICAL FEATURES:- Capsular ligament can be palpated by finger pressure over lateral pole of the condyle. Pain caused by this indicates capsulitis. Limited opening secondary to pain.

Soft end feel noted. If edema present, condyle displaced inferiorly causing disocclusion of ipsilateral posterior teeth.

2. RETRODISCITIS:-

Inflammation of retrodiscal tissue due to macrotrauma. This trauma suddenly forces the condyle posteriorly into retrodiscal tissue & secondary inflammation may results.

Microtrauma may also cause this, such as in the progressive phase of disc displacement. During this condyle gradually encroached on inferior retrodiscal lamina.

HISTORY:- Incidence of trauma. Constant pain, accentuated by movement. Clenching of teeth → ↑ pain.

CLINICAL FEATURES:- limited opening, soft end feel. If retrodiscal tissue swells, condyle moves forward & downwards which cause malocclusion or disocclusion of ipsilateral post & heavy contact of contralateral side.

3. ARTHRITIS:- Inflammation of articular surfaces of the joint. Several types of arthritis affect the joint.

a. OSTEOARTHRITIS & OSTEOARTHROSIS:-

CAUSE:-

OSTEOARTHRITIS: A destructive process by which the bony articular surfaces of condyle & fossa become altered.

It is body’s response to loading. Due to loading the articular surfaces become soften, subarticular bone begun to resorb. Progressive destruction results in loss of subchondral cortical layer, bone erosion & radiographic evidence of osteoarthritis.

OSTEOARTHROSIS: Once loading is ↓, the arthritic condition becomes adaptive, yet morphology remains altered.

Most commonly osteoarthritis associated with disc dislocation or perforation. Once disc is dislocated & retrodiscal tissue breakdown, condyle begins to articulate directly with fossa accelerating the destructive process. Overloading of joint may be result of high levels of parafunctional activity.

HISTORY:- Unilateral joint pain aggravated by movement. Pain is constant but may be worsen in late afternoon or evening. In osteoarthrosis. it represents a stable adaptive phase, the pt doesnot report symptoms.

CLINICAL FEATURES:- Joint pain, limited opening, soft end feel, crepitation typically felt.

TMJ radiographs ; evidence of structural changes in subarticular bone.(erosions, flattening)

4. POLYARTHRITIS:-

A group of disorders in which articular surfaces become inflamed. Each is identified according to causative factors.

A. TRAUMATIC ARTHRITIS:- Macrotrauma to jaws can cause surface changes that produce inflammation.

Positive history of macrotrauma & can be closely related to onset of symptoms. Reports constant arthralgia accentuated with movement.

Limited opening secondary to pain, soft end feel, acute malocclusion if swelling is present.

B. INFECTIOUS ARTHRITIS:- Asso. With a systemic disease as immunologic response. Non sterile type results from bacterial invasion by penetrating wounds.

HISTORY:- Infection of adjacent tissue or wound with constant pain accentuated with movement. Joint swelling with increase temp sometimes.

C. RHEUMATOID ARTHRITIS:- The precise cause is unknown. Inflammation of synovial membrane that extends into surrounding CT & articular surfaces which become thicken & tender.

As force is placed of this surface, synovial cells release enzymes that damage joint tissue especially cartilage. In severe cases, osseous tissue can resorb with significant loss of condylar support.

HISTORY:- always bilateral, multiple joints complaint. Acute malocclusion in severe cases with heavy posterior contacts & anterior open bite.

INTERNAL DERRANGEMENT OF CONDYLE-DISC COMPLEX

Derangements of the condyle-disc complex present as a range of conditions, most of which can be viewed as a continuum of progressive events. They occur because the relationship between the articular disc and the condyle changes.

The disc is laterally and medially bound to the condyle by the discal ligaments; thus translatory movement in the joint can occur only between the condyle-disc complex and the mandibular fossa. The only physiologic movement that can occur between the condyle and the articular disc is rotation.The disc can rotate on the condyle around the attachments of the discal ligaments to the poles of the condyle. The extent of rotational movement is limited by the length of the discal ligaments and by the inferior retrodiscal lamina posteriorly and the anterior capsular ligament anteriorly. The amount of rotation of the disc on the condyle is also determined by the morphology of the disc, the degree of interarticular pressure, and the superior lateral pterygoid muscle, as well as the superior retrodiscal lamina.

When the mouth opens and the condyle moves forward, the superior retrodiscal lamina becomes more tight, rotating the disc posteriorly on the condyle. Interarticular pressure provided by the elevator muscles maintains the condyle on the thinner intermediate zone of the articular disc and prevents the thicker anterior border from passing posteriorly through the discal space between the condyle and the articular surface of the articular eminence. When a person bites on something resistant, the interarticular pressure decreases on the biting side. To stabilize the joint during this power stroke, the superior lateral pterygoid muscle pulls the condyle-disc complex forward. The fibers of the superior lateral pterygoid muscle that are attached to the disc produce a forward rotation of the disc, allowing the thicker posterior border to maintain intimate contact between the two articular surfaces.

The superior retrodiscal lamina is the only structure that can retract the disc posteriorly. In the healthy joint the surfaces of the condyle, disc, and mandibular fossa are smooth and slippery and allow easy friction less movement. The disc therefore maintains its position on the condyle during movement because of its morphology and interarticular pressure. Its morphology (i.e., the thicker anterior and posterior borders) provides a self positioning feature that, in conjunction with the interarticular pressure, centers it on the condyle.

If the morphology of the disc is altered and the discal ligaments become elongated, the disc is then permitted to slide (translate) across the articular surface of the condyle. In the normal closed joint position and during function, interarticular pressure still allows the disc to position itself on the condyle and no unusual symptoms are noted. Alteration in the morphology of the disc accompanied by elongation of the discal ligaments can change this normal functioning relationship.

In the resting closed joint position the interarticular pressure is very low. If the discal ligaments become elongated, the disc is free to move on the articular surface of the condyle. As the mouth opens and the condyle moves forward, a short distance of translatory movement can occur between the condyle and the disc until the condyle once again assumes its normal position on the thinnest area of the disc (intermediate zone), in which, the interarticular pressure maintains this relationship and the disc is again carried forward with the condyle through the remaining portion of the translatory movement.The important feature of this functional relationship is that the condyle translates across the disc to some degree when movement begins. This type of movement does not occur in the normal joint. During such movement, the increased interarticular pressure may prevent the articular surfaces from sliding across each other smoothly. The disc can stick or be bunched slightly, causing an abrupt movement of the condyle over it into the normal condyle-disc relationship, often accompanied by a clicking sound.

During closing of the mouth, the normal relationship of the disc and the condyle is maintained because of interarticular pressure. However, once the mouth is closed and the interarticular pressure is lower, the disc can once again be displaced forward by tonicity of the superior lateral pterygoid muscle. The single click observed during opening movement represents the very early stages of disc derangement disorder what is also called internal derangement. If this condition persists, a second stage of derangement is noted. As the disc is more chronically repositioned forward and medially by muscle action of the superior lateral pterygoid muscle, the discal ligaments are further elongated. Continued forward positioning of the disc also causes elongation of the inferior retrodiscal lamina. Accompanying this breakdown is a continued thinning of the posterior border of the disc, which permits the disc to be repositioned more anteriorly, resulting in the condyle being positioned more posteriorly on the posterior border. The morphologic changes of the disc at the area where the condyIe rests can create a second click during the later stages of condylar return just prior to the closed joint position. This stage of derangement is called the reciprocal click.

Reciprocal clicking is characterized as follows:

1. During mandibular opening a sound is heard that represents the condyle moving across the posterior border of the disc to its normal position on the intermediate zone. The normal condyle-disc relationship is maintained through the remaining opening movement..

2. During closing the normal disc position is maintained until the condyle returns to very near the closed joint position.

3. As the closed joint position is approached, the posterior pull of the superior retrodiscal lamina is decreased.

4. The combination of disc morphology and pull of the superior lateral pterygoid muscle allows the disc to slip back into the more anterior position, where movement began. This final movement of the condyle across the posterior border of the disc creates a second clicking sound and thus the reciprocal click.

The opening click can occur at any time during that movement depending on condyle-disc morphology, muscle pull, and the pull of the superior retrodiscal lamina. The closing click almost always occurs very near the closed or intercuspal position. The longer the disc is displaced anteriorly and medially, the greater the thinning of its posterior border and the more the lateral discal ligament and inferior retrodiscal lamina will be elongated. Also, protracted anterior displacement of the disc leads to a greater loss of elasticity in the superior retrodiscal lamina. The more the shape of the disc changes to accommodate the pull of the muscle and position of the condyle, the greater the likelihood that the disc will be forced through the discal space, collapsing the joint space behind. In other words, if the posterior border of the disc becomes thin, the superior lateral pterygoid muscle can pull the disc completely through the discal space.

When this occurs, interarticular pressure collapses the discal space, trapping the disc in the forward position. Then the next full translation of the condyle is inhibited by the anterior and medial position of the disc. The person feels the joint being locked in a limited closed position. Since the articular surfaces have actually been separated this condition is referred to as a functional dislocation of the disc.

Some persons with a functional dislocation, of the disc are able to move the mandible in various lateral directions to accommodate the movement of the condyle over the posterior border of the disc, and the locked condition is resolved. If the lock occurs only occasionally and the person can resolve it with no assistance, it is referred to as a functional dislocation with reduction. Often a patient reports that the jaw "catches" when opening wide. This condition may or may not be painful depending on the severity and duration of the lock and the integrity of the structures in the joint. If it is acute, having a short history and duration, joint pain may only be associated with elongation of the joint ligaments (such as trying to force the jaw open). As episodes of catching or locking become more frequent and chronic,

ligaments break down and innervations is lost. Pain becomes less associated with ligaments and more related to forces placed on the retrodiscal tissues.

The next stage of disc derangement is known as functional disc dislocation without reduction. This condition occurs when the person is unable to return the dislocated disc to its normal position on the condyle. The mouth cannot be opened maximally because the position of the disc does not allow full translation of the condyle. Typically the initial opening is only 25 to 30 mm interincisally, which represents tile maximum rotation of tile joint. The person usually is aware of which joint is involved and can remember the occasion that led to the locked feeling. Since only one joint usually becomes locked, a distinct pattern of mandibular movement is observed clinically.

The joint with the functionally dislocated disc without reduction does not allow complete translation of its condyle, whereas the other joint functions normally. Therefore when the patient opens the mouth widely, the midline of the mandible is deflected to the affected side. Also the patient is able to perform a normal lateral movement to the affected side (the condyle on the affected side only rotates). However, when movement is attempted to the unaffected side, a restriction develops (the condyle on the affected side cannot translate past the anterior functionally' dislocated disc). The dislocation without reduction has also been termed a closed lock. Patients may report pain when the mandible is moved to the point of limitation, but pain does not necessarily accompany this condition.

Any condition or event that leads to elongation of the discal ligaments or thinning of the disc can cause these derangements of the condyle-disc complex disorders. Certainly one of the most common factors is trauma. Two general types of trauma must be considered: Macrotrauma and microtrauma.

Macrotrauma:- Macrotrauma is considered any sudden force to the joint that can result in structural alterations. Macrotrauma can be subdivided into two types: direct trauma or indirect trauma.

Direct trauma: There is little question that significant direct trauma to the mandible, such as a blow to the chin, can instantly create an intracapsular disorder. If this trauma occurs when the teeth are separated (open mouth trauma) the condyle can be suddenly displaced within the fossa. This sudden movement of the condyle is resisted by the ligaments. If the force is great, the ligaments can become elongated, which may compromise normal condyle-disc mechanics. The resulting increased

looseness can lead to discal displacement and to the symptoms of clicking and catching. If trauma occurs to the mandible when the teeth are together, the intercuspation of the teeth maintains the jaw position, resisting joint displacement. Closed mouth trauma is not likely to be without some consequence.

Although ligaments may not be elongated, articular surfaces can certainly receive sudden traumatic loading. This type of impact loading may disrupt the articular surface of the condyle, fossa, or disc, which may lead to alterations in the smooth sliding surfaces of the joint, causing roughness and even sticking during movement. This type of trauma therefore may result in adhesionsDirect trauma may also be iatrogenic. A few common examples of iatrogenic trauma are intubation procedures, third molar extraction procedures, and a long dental appointment. In fact, any extended wide opening of the mouth (e,g., a yawn) lias the potential of elongating the discal ligaments.

Indirect trauma: Indirect trauma refers to injury that may occur to the TMJ secondary to a sudden force, that does not directly Impact or contact the mandible.The most common type of indirect trauma reported is associated with a cervical flexion-extension injury (whiplash injury).

Microtrauma:- Microtrauma refers to any small force that is repeatedly applied to the joint structures over a long period of time. The dense fibrous connective tissues that cover the articular surfaces of the joints can well tolerate loading forces. In fact, these tissues need a certain amount loading to survive, since loading forces drive synovial fluid in and out of the articular surfaces passing with it nutrients coming in and waste products going out. If, however, loading exceeds the functional limit of the tissue, irreversible changes or damage can result.

When the functional limitation has been exceeded the collagen fibrils become fragmented, resulting in a decrease in the stiffness of the collagen network. This allows the proteoglycan water gel to swell and flow out into the joint space, leading to a softening of the articular surface. This softening is called chondromalacia. This early stage of chondromalacia is reversible if the excessive loading is reduced. If, however, the loading continues to exceed the capacity of the articular tissues, irreversible changes can occur. Regions of fibrillation can begin to develop, resulting in focal roughening of the articular surfaces. This alters the frictional characteristics of the surface and may lead to sticking of the articular surfaces, causing changes in the mechanics of condyle-disc movement. Continued sticking or roughening leads to strains on the discal ligaments during movements and eventually disc displacements.

Microtrauma can result from joint loading associated with muscle hyperactivity such as bruxism or clenching. Another type of microtrauma results from mandibular orthopedic instability. As previously described, orthopedic stability exists when the stable intercuspal position of the teeth is in harmony with the musculoskeletally stable position of the condyles. When this condition does not exist, microtrauma can result.

FACTORS THAT PREDISPOSE TO DISC DERANGEMENT DISORDERS :-

1) Steepness of the articular eminence: The degree of steepness of the posterior slope greatly influences condyle disc function. In a patient with a flat eminence, there is a minimum amount of posterior rotation of the disc on the condyle during opening. As the steepness increases, more rotational movement is required between the disc and the condyle during translation of the condyle. Therefore, patient's with steep articular eminence are more likely to demonstrate greater condyle disc movement during function. This exaggerated condyle-disc movement may increase the risk of ligament elongation that leads to disc-derangement disorders.

2) Morphology of the condyle and fossa: Flat or gable like condyles that articulate against inverted V-shaped temporal components seem to have an increased incidence of disc derangement disorders and degenerative joint diseases.

3) Joint Laxity: Ligaments act as guide wires to restrict certain movements of the joint. Although the purpose of ligaments is to restrict movement, the quality and integrity of these collagenous fibres vary from patient to patient. As a result, some joints show slightly more freedom or laxity than others. Several studies suggest a relationship between generalized joint laxity and certain TMD symptoms. Some generalized laxity may be due to increased levels of estrogen. For e.g. women's joints are generally more flexible and lax than men's.

The derangements are divided into two subcategories for the purpose of treatment :- (1) disc displacement and disc dislocation with reduction, and (2) disc dislocation without reduction.

A. DISC DISPLACEMENT AND DISC DISLOCATION WITH REDUCTION

These represent the early stage of disc derangement disorders.Clinical characteristics:

The clinical examination reveals a relatively normal range of movement with restriction only associated with the pain. Discal movement can be felt by palpation of the joints during opening and closing. Deviations in the opening pathway are common.

Definitive Treatment:It aims at re-establishing a normal condyle-disc relationship. In early 1970s, Farrar introduced the anterior positioning appliance that provided an occlusal relationship that required the mandible to be maintained in a forward position. The position selected for the appliance is one that positions the mandible in the least protruded position that re-establishes the normal condyle-disc relationship. This is usually achieved clinically by monitoring the clicking joint. Although eliminating the click does not always denote successful reduction of the disc, it is a good clinical reference point for beginning therapy. The idea behind the anterior positioning appliance was to reposition the condyle back on the disc ("recapture the disc"). Joint sounds are very common in the general population. In most cases, they do not appear to be related to pain or decreased joint mobility. If all clicking joints always progressed to more serious disorders, this would be a good indication that each and every joint that clicked should be treated. The presence of unchanging joint sounds over time, however, indicates that some structures can adapt to less than optimum functional occlusion.It was also found that long term osseous changes in the condyle were commonly associated with disc dislocation without reduction and not so commonly associated with disc dislocation with reduction. The treatment goal of definitive therapy is to reduce intracapsular pain, not to recapture the disc. A stabilization appliance should be used whenever possible because adverse long-term effects are minimized.

When this appliance is not effective, an anterior positioning appliance should be fabricated. The patient should be initially instructed to wear the appliance every night during sleep and during the day only when needed to reduce symptoms. This part-time use minimizes adverse occlusal changes. The patient should be encouraged to wear the appliance more only if it is the only way the pain can be controlled. As symptoms resolve, the patient is encouraged to decrease use of the appliance. With adaptive changes, most patients can gradually reduce the use of the appliance with no need for any dental changes. These adaptive changes can take 8 to 10 weeks or even longer.

Supportive Therapy:

The patient should be educated about the mechanics of the disorder and the adaptive process that is essential for treatment. The patient must be encouraged to decrease loading of the joint whenever possible. Softer foods, slower chewing, and smaller bites should be promoted. The patient should be told, when possible, not to allow the joint to click. If inflammation is suspected, an NSAID should be prescribed. Moist heat or ice can be used if the patient finds either helpful. Active exercises are not usually helpful, since they cause joint movements that often increase pain. Passive jaw movements may be helpful, and on occasion distractive manipulation by a physical therapist may assist in healing.

B. DISC DISLOCATION WITHOUT REDUCTION It represents the clinical condition in which the disc is dislocated, most frequently anteromedially, from the condyle and does not return to normal position with condylar movement.

Clinical Characteristics:Examination reveals limited mandibular opening (25- 30 mm) with normal eccentric movement to the ipsilateral side and restricted eccentric movement to the contralateral side.

Definitive Treatment:In such cases, the anterior positioning appliance will only aggravate the condition by forcing the disc even more forward and is therefore contraindicated.When the condition is acute, the initial therapy should include an attempt to reduce or recapture the disc by manual manipulation. In patients with a longer history, success begins to decrease rapidly (as they are likely to present with disc and ligaments that have undergone changes that will not allow reduction of the disc).If the disc is not successfully reduced, a second and possibly a third attempt is needed. Failure to reduce the disc may indicate a dysfunctional superior retrodiscal lamina. Once this tissue has lost its elasticity and ability to retract the disc, the dislocation becomes permanent.

Supportive Therapy:It should begin with educating the patient about the condition. If the patient's attempt to force their mouth strongly to open wider, it only aggravates the intracapsular tissues, producing more pain. Patients should be encouraged not to open wide especially immediately following the dislocation. With time and tissue adaptation, they will be able to return to a more normal range of movement (usually more than 40 mm).

The patient should also be told to decrease hard biting, never chew gum and generally avoid anything that aggravates the condition. If pain is present, heat or Ice may be used. NSAIDs are indicated for pain and inflammation. Joint distraction and phonopheresis over the joint area may be helpful.

STRUCTURAL INCOMPATIBILITY OF THE ARTICULAR SURFACES

It can be divided into four categories;

I} Deviation in formIt depicts a group of disorders that is created by changes in smooth articular surface of the joint and disc. These changes produce an alteration in the normal pathway of condylar movement.

Clinical Characteristics:A repeated alteration in the pathway of the opening and closing movements is seen. When a click or deviation in opening is noted, it always occurs at the same position of opening and closing. Deviations in form may or may not be painful.

Definitive Treatment:Definitive approach is to return the altered structure to normal form (often accomplished by a surgical procedure). In the case of bony incompatibility, the structures are smoothed and rounded. If the disc is perforated, it is repaired (discoplasty).

Supportive Therapy:The patient should be encouraged, when possible, to learn a manner of opening and chewing that avoids or minimizes the dysfunction. In some cases, the increased interarticular pressure associated with bruxism can accentuate the dysfunction associated with deviations in form. In such a case, a stabilization appliance is indicted to decrease the muscle hyperactivity. If pain is associated, analgesics may be necessary to prevent the development of secondary central excitatory effects.

2} Adherences and AdhesionsThese represent a temporary sticking of the articular surfaces during normal joint movements. Adhesions are more permanent and are caused by a fibrotic attachment of the articular surfaces. Adherences and adhesions may occur between the disc and condyle or the disc and fossa.

Clinical Characteristics:

The presenting symptom for adherences is temporary restriction in mouth opening until the click occurs, whereas the presenting symptom in adhesions is a more permanent restriction in mouth opening. If the adhesions affect only one joint, the opening movement deflects to the ipsilateral side, When adhesions are permanent, the dysfunction can be great. Adhesions in the inferior joint cavity cause a sudden jerky movement during opening. Those in the superior joint cavity restrict movement to rotation. During mouth opening adhesions between disc and fossa tend to force the condyle across the anterior border of the disc.With a posterior dislocation, the patient opens normally but has difficulty getting the teeth back into occlusion. Pain mayor may not be present. If pain is a symptom, it is normally associated with attempts to increase opening that elongate ligaments.

Definitive Treatment:It is directed towards decreasing loading of the articular surfaces. Loading may be related to nocturnal clenching. When this is suspected, a stabilization appliance is indicated for decreasing the muscle hyperactivity. .When adhesions are present, breaking the fibrous attachment is the only definitive treatment (can be achieved with arthroscopic surgery) and the lavage used to irrigate the joint during the procedure assists in decreasing symptoms.

Supportive Therapy:The restriction of some adhesion problems can be improved with passive stretching, ultrasound, and distraction of the joint. These type of therapies tend to loosen die fibrous attachments, allowing more freedom for movement. Too aggressive stretching, however, can tear tissues and produce inflammation and pam. When pain and dysfunction are minimal, patient education is the most appropriate treatment. Having the patient limit opening and learn appropriate patterns of movement that do not aggravate the adhesions can lead to normal functioning.

3}Subluxation:Also known as hypermobility is a clinical description of the condyle as it moves anterior to the crest of the articular eminence. It is not a pathologic condition but reflects a variation in anatomic form of the fossa.

Clinical Characteristics:During the final stage of maximal mouth opening, the condyle can be seen to suddenly jump forward with a "thud" sensation. This is not reported as a subtle clicking sensation.

Definitive Treatment:

Only definitive treatment is surgical alteration of the joint itself. Eminectomy reduces the steepness of the articular eminence and thus decreases the amount of posterior rotation of the disc on the condyle during full translation.

Supportive Therapy:It begins by educating the patient regarding the cause of subluxation and which movements create the interference. The patient must also learn to restrict opening. On occasion, when the interference cannot be voluntarily resolved, an intraoral crevice to restrict movement is employed that develops a myostatic contracture of the elevator muscle, thus limiting mouth opening to the point of subluxation.

4} Spontaneous DislocationIt is commonly referred to as an open lock. It can occur following wide open mouth procedures: This condition refers to a spontaneous dislocation of both the condyle and the disc. .

Clinical Characteristics:The patient remains in a wide open mouth condition. Pain is commonly present secondary to the patient's attempts to close the mouth.

Definitive Treatment:It is directed towards increasing the disc space, which allows the superior retrodiscal lamina to retract the disc. Since the mandible locked open, the patient generally tends to contract the elevator muscles in an attempt to close it in the normal manner. This activity aggravates the spontaneous dislocation. When attempts are being made to reduce the dislocation, the patient must open wide as if yawning. This activates the mandibular depressor muscles and inhibits the elevator muscles.If the inferior lateral pterygoid muscle is in a myospasm, preventing posterior positioning of the condyle, it is appropriate to inject the muscle with local anesthetic without a vasoconstrictor in an attempt to eliminate the myospasms and promote relaxation. When spontaneous dislocation becomes chronic or recurrent, definitive treatment may consist of a surgical procedure directed towards correcting the structures that contribute to the disorder.

Supportive Therapy:The most effective method of treating spontaneous dislocation is prevention. When a spontaneous dislocation is recurrent, the patient is taught the reduction technique. Chronic recurrent dislocations can be definitively treated by a surgical procedure only after supportive therapy has failed to eliminate or reduce the problem to an acceptable level.

HYPOMOBILITY OF JOINT:

1. TMJ ankylosis:Ankylosis- greek word- stiff joint

- Incidence in india- high.- Age distribution- 2- 6 years

Mean age: 10 years- Classification:

1. False and true2. Extra articular or intra articular3. Fibrous or bony4. Unilateral or bilateral5. Partial or complete

- Grading of ankylosis by sewhey (1986)Type- 1: Condylar head is present without much distoetion fibrous adhesions made movement imposible.Type 2: bony fusion of misshaped head and articular surface. No involment of sigmoid notch and coronoid process.Type 3: bony block bridging across the ramus and zygomatic arch. Medially an atrophic dislocated fragment of former head is still found. Elongation of coronoid seen.Type 4: normal anatomy is totally destroyed by complete bony block between ramus and skull base.

Etiopathology: 1. Trauma(26- 75%)2. Infection (44- 68%)

Joint infection: septicemia due to osteomyelitis, septic soar throat, scarlet fever, TB, meningitis.

- Direct spread of infection: otitis media, mastoditis, soft tissue abscess, skin infection.

- Diseases affecting joint: rheumatoid arthritis, osteoarthritis, spondylitis.Trauma: at brith: forceps delivery.

- Fracture of condyle- Direct blow at joint or chin cause bleeding. Prolonged immobilization of

Condylar fracture.Pathogenesis:

- Trauma – extravasation of blood in joint. (hemarthrosis)

- Predisposes to calcification and obliteration of joint space.- Immobility of the joint for prolonged period- initially fibrous bands lead

towards bony consolidation to ossification.Clinical manifestation:

- Severity, time of onset, duration.- Early joint involvement: < 15 yrs: severe deformity and loss of function.- Later joint involvement: after 15 yrs: facial deformity marginal or nil,

severe function loss.UNILATERAL ANKYLOSIS:

- Obvious facial asymmetry.- Deviation of mandible and chin of affected side.- Chin is secreted on affected side.- Roundness or fullness of face on affected side.- Appearance of flatness and elongation on unaffected side.- Well defined antegonial notch on affected side.- Some amount of oral opening. Crossbite may be seen.- Affected side: class 2 malocclusion, on ipsilateral side. Unilateral posterior

crossbite.- Affected side Condylar movement absent.

BILATERAL ANKYLOSIS:- Inability to open mouth.(gradual decreasing )( < 5 mm)- Mandible is symmetrical but micrognathic.- Neck chin angle may reduced or absent. Bird face appearance.- Antegonial notch prominent bilaterally.- Class 2 malocclusion.- Upper incisors- protrusive with anterior open bite. Maxilla may be narrow.- Multiple carious teeth with bad periodontal health. Severe malocclusion,

crowding. Diagnosis:H/o trauma, infectionClinical findingsRadiographs: OPG, Lat. Oblique, Cephalomatric radiographs, PA skull, CT scan.

FIBROUAS ANKYLOASIS: Reduced joint space, hazy appearance, normal anatomy may be appreciated.BONY ANKYLOSIS: Complete obliteration of joint space, normal anatomy distorted, elongated coronoid process.

Management: Always surgical.Aims & objectives:

- Release of ankylosed mass & creation of gap.- Creation of functional joint.- Reconstruct the joint & vertical height of ramus.- To improve esthetics.

Techniques :1. CONDYLECTOMY:

- Commonly used in fibrous ankylosis.- Clinically after exposure can see the demarcation between the roof & head

on condyle.- Osteotomy cut at level of condyle neck. Head should be separated from

the sup. Attachment carefully.- Rest of the stump is smoothen & wound is closed.- Unilateral condylectomy : Deviation towards operated side.- Bilateral : Ant open bite, loss height of vertical ramus.

2. GAP ARTHROPLASTY:- In extensive ankylosis, a broad thick area of bone deposition obliterates

the entire joint.- The level of section is below that of previous joint space and no substances

is interposed.- Two horizontal cuts to create minimum gap of 1 cm to prevent reankylosis.

3. INTERPOSITIONAL GAP ARTHROPLASTY:- Most authorities agree that recurrence is less likely when something is

interposed between to cuts. In gap arthroplasty – 53% recurrence.- Creation of gap but in addition a barriers is inserted between the cut bony

surfaces to minimize resk of recurrence and to maintain the vertical height of ramus.

- Materials used,- AUTOGENOUS:- Cartilaginous grafts: costochondral, metatarsal, sternoclavicular,.- Temporal muscle, temporal fascia, fascia lata, dermis.- HETEROGENOUS:- Chromatized submucosa of pig bladder, lypholized bovine cartilage.- ALLOGRAFTS:- Metallic: tentalium foil, 318L ss, titanium. Gold.- Non-metallic: silastic, teflon, acrylic, nylon, proplast, ceramic implants.

MUSCLE CONTRACTURE:

A painless shortening of muscle. Two types: 1. Myostatic 2. Myofibrotic. Contracture of elevator muscles produce hypomobility.

1. Myostatic contracture:When a muscle is kept from fully lengthening for a prolong time. Full lengthening cause pain in associated structures. Sometimes secondary to other disorder. Patient was on ant repositioning appliance continuously leads to inf lateral pterygoid would not allowed to fully lengthen. A myostatic contracture can develop that disallows the condyle to immediately return to stable position.

History: Long distance of restricted jaw movement. It may began secondary to a pain condition that has now resolved.

Clinical features: painless limitation of mouth opening.

Definitive treatment: Original cause is identified & resolved, then treatment is directed towards the gradual lengthening of involved muscle.If pain : protective co-contraction- treatment will fail.Exercises: passive stretching & resistant opening.Passive stretching: it is accomplished when pt open to the full limit & gently stretching beyond the restriction. Gentle & momentary, not to traumatize the muscle.Resistance opening: Take advantage of neurologic reflex system to aid in relaxation. Mandibular elevators & depressor function according to reciprocal inhibition. Neurologic stretch reflex help in control of this activity.Initiating mild contraction of antagonist muscle groups, when elevators will not properly relax, contraction of depressor provided by resistance to opening feeds neurologic input to elevators tpo relax. Supportive therapy: little use.

- Analgesics, thermotherapy, ultrasound.

TUMORS OF THE TMJ

Benign tumors :ChondroblastomaChondromaCondylar hyperplasiaFibrous dysplasiaGiant cell granulomaHemangioma

Osteochondroma and Osteoma

Malignant tumors: ChondrosarcomaMultiple myelomaOsteosarcomaSynovial sarcoma

BENIGN TUMORS

1. ChondroblastomaIt is a distinct entity that usually involves the long bones but sometimes occurs in the cranial bones and in the mandibular condyle. This benign central bone tumor occurs predominantly in young people. The incidence in males is roughly double that in female. Conservative surgical excision is generally acceptable treatment. Characteristic histological presentation is called chiken-wire pattern.

2. Chondroma:This neoplasm demonstrates no sex predilection and may develop at any age. Chondroma generally presents as a painless, slowly enlarging swelling. The radiographic appearance is that of an irregular radiolucent or mottled region of the bone.. The histopathologic distinction between a chondroma and a well differentiated low grade chondrosarcoma of the TMJ is often difficult, therefore, many pathologists suggest that any chondroma of the jaws should be regarded as potentially a low grade chondrosarcoma.

3. Condylar HyperplasiaAlthough space-occupying benign or malignant lesions can displace the condyle from the fossa and cause asymmetry with malocclusion, Condylar-hyperplasia can have similar presenting symptoms. Its etiology is not well understood. The articular surface of a normal condyle is composed of fibrocartilage that exhibits appositional growth incontrast to endochondral ossification.

It has been categorized into two types :-Type I deformity, or hemimandibular elongation, is the most common variant. The mandible is asymmetric, with deviation of the chin to the contralateral side and a concomitant dental cross-bite.Type II deformity, or hemimandibular hypertrophy, where deviation of chin is not a prominent feature, but a marked vertica1 open-bite is present on the ipsilateral side of the hypertrophy. .

Condylar hyperplasia is not a truly neoplastic process but actually a self-limited disorder. If the disorder is diagnosed early in its active stage, removal shaving of only 5 or 6 mm of the most superior condylar surface is usually adequate, and condylectomy is unnecessarily aggressive. Recontouring the inferior border and the angle of the mandible is sometimes necessary to correct the inferior component of the asymmetry. In an inactive process, orthognathic procedures, such as a vertical subsigmoid osteotomy can be useful in correcting an open bite while maintaining a functional joint articulation.

4. Fibrous DysplasiaThis most commonly presents as an asymptomatic, slow enlargement of the involved bone. Monostotic fibrous dysplasia' accounts for up to 80 % of the cases. Jaw involvement is common in this form of the disease. The entire ramus-condyle-complex can be involved and present as facial asymmetry.Clinical presentation is difficult to distinguish from that of condylar hyperplasia. The radiographic presentation is sometimes similar to that of' Garre's osteomyelitis. Once pathologic diagnosis is confirmed by biopsy, the only treatment required may be periodic follow-up. However, if significant cosmetic or functional deformity has occurred, surgical intervention with osseous recontouring may be undertaken.Aneurysmal bone cysts have also been reported in association with fibrous dysplasia. Fibrous dysplasia shares many microscopic features with ossifying fibroma.

5. Giant Cell GranulomaThis disease is seen predominantly in children and young adults, with 75 % of the cases presenting before the age of 30 years. Females are affected approximately twice as frequently as males. Lesions occur more frequently in the mandible than in the maxilla. Giant cell granuloma typically presents as a painless expansion or swelling of the affected jaw. Radiographic appearance is frequently a unilocular or multilocular radioluscency.The clinical behavior is widely variable. Some may progress slowly with only minimal destruction of bone. The more aggressive variety may progress rapidly and result in massive bone loss and cortical perforation. The treatment may vary from simple enucleation of small, slowly enlarging lesions to condylectomy or wide resection of aggressive, rapidly enlarging lesions.

6. HemangiomaThe maxilla and the mandible are the most common sites of occurrence of hemangioma of bones after the vertebrae and skull. The posterior mandible is the most frequent site of incidence in the jaws. The lesion commonly presents as a firm, slowly enlarging, exp-ansile swelling of the bone. Spontaneous intra-oral bleeding

may occur. Bruits and pulsations of large hemangiomas may be detected with careful auscultation or palpation of the thinned cortical plates. Common radiographic presentation is that of a multilocular radioluscency. Its most significant feature if the life-threatening hemorrhage that may occur if these lesions are improperly managed. Management may include embolization, sclerosing agents, and surgery.

7. Osteochondroma and OsteomaThese are the two most common tumors of the TMJ. Radiographic studies frequently reveal an abnormally shaped condyle or a tumor mass attached to an abnormally shaped condyle. The condylar neck is usually of normal length. Also, the growth rate is usually slower than that of Condylar hyperplasia. The anatomic location and size of most benign tumors of the condyle are such that a condylectomy is usually warranted to ensure complete removal.MALIGNANT TUMORS

1. ChondrosarcomaChondrosarcoma of the mandible and maxilla is extremely rare, accounting for approximately 1 % of all chondrosarcomas. Most mandibular chondrosarcomas present in the mandibular body, with an occasional occurrence in the condylar process. No gender predilection has been noted, and it is present predominantly in adulthood. Although the mean age of occurrence is 60 years, almost half of the cases arise in the third and fourth decade of life.The most common presentation is that of a painless swelling, with expansion of the underlying bone. The radiographic appearance varies from moth-eaten radioluscencies that are solitary or multilocular to diffusely radiopaque lesions. Because chondrosarcomas are radio-resistant neoplasms, wide local or radical surgical excision is the treatment of choice. The 5-year survival rate for chondrosarcoma of the mandible is 17 %.

2. Multiple MyelomaPlasma cell neoplasms are derived from bone marrow stem cells of B-Iymphocyte. multiple myeloma occurs after the fifth decade, with a mean range of occurrence of 63 years. Involvement of the jaws may be asymptomatic or may produce pain, swelling, expansion, numbness, and pathologic fracture. The radiographic appearance is typically that of multiple punched out but non-corticated radiolucent areas of bone destruction. Occasionally, the lesions may be expansile or radiographically sclerotic. Treatment usually consists of chemotherapy with radiation directed at painful lesions.

3. OsteosarcomaApproximately 5 % of osteosarcomas occur in the jaws. These are reportedly associated with several pre-existing bone abnormalities, including Paget's disease, fibrous dysplasia, giant cell tumor, multiple osteochondroma, bone infarct, chronic osteomyelitis, and osteogenesis imperfecta. Other osteosarcomas occur subsequent to radiation therapy to the affected region for unrelated or antecedent disease.The peak incidence of osteosarcoma of the jaw is in the third or fourth decade, with a mean age of 34 years. The majority of mandibular osteosarcomas arise in the body (60%), with those arising in the TMJ accounting for a small percentage. Osteosarcomas of the TMJ commonly present as rapidly enlarging, painful localized swelling. Paresthesia may occur secondary to involvement of the trigeminal nerve. Variants of osteosarcoma that ma)' affect the TMJ are osteoblastic, fibroblastic and chondroblastic osteosarcomas. The typical radiographic appearance is that of a lytic lesion. Treatment generally consists of radical wide excision. Radiotherapy and chemotherapy are reserved for recurrence. The 5-year survival rate for osteosarcoma of the jaws IS25% to 50%. The most common sites for metastasis are the lung and the brain, with extremely rare involvement of regional lymph nodes.

4. Synovial Sarcoma Synovial sarcoma of the head and neck area is predominantly a disease of young people, the median age being 19 years. A painless, deep-seated swelling is commonly the presenting complaint. Early radical excision is probably the best treatment for synovial sarcoma of the head and neck. In other sites; the 5year survival rate varies between 25% and 50%.

TMJ begins development in the 10th week of gestation Two mesenchymal condensations develop- one for temporal bone

component(glenoid fossa) and one for condylar component The intervening mesenchyme also shows a condensation of cells that

diffrentiate into the intervening disc(meniscus) The temporal and condylar mesenchymal cells diffrentiate into

osteoblast to lay membranous bone The centre of the condylar component develop s into white

fibrocartilage that facilitates subcondral bone formation thus contributing for condylar growth till adulthood

The meniscus develpos into highly vascular disc that continues anteriorly into the lateral pterygoid muscle and posteriorly as discomalleolar ligament (pintos ligament)