DISORDERS OF THE TEMPORO-MANDIBULAR JOINT (TMJ)Dr. Mohamed ShokryBDS-MSc-PhDOral & Maxillofacial SurgeryFaculty of Dentistry- Alexandria

Unique joint, its structure allowing for three different groups of movements: 1. The up and down, or elevation and depression, of the jaw.2. The protraction &retraction of the mandible .3. Side to side motion, or lateral deviation. Bony articulation and interposed disc The condyle is roughly elliptical in cross section with the medio-lateral dimension equal to about twice its antero-posterior width.The articular surfaces are covered with avascular fibrous tissue.The primary concave temporal articular surface is limited anteriorly by the convex articular eminence and posteriorly by the articular lip.Interposed between the osseous structures is the meniscus (disc).It is composed of avascular, aneural, fibrous connective tissue.

Disc And Its Attachments:The disc separates the superior and inferior joint cavities.It is lined with synovial tissues that produce fluid necessary for lubrication of articular surfaces.The upper cavity is larger.The disc composed of three regions:-3 mm: Posterior band.1 mm: Intermediate zone.2 mm: Anterior band.It is thinnest centrally (1mm) and somewhat heavier along its periphery.The greatest bulk is at the posterior attachment (the bilaminar zone)The bilaminar zone consists of two strata of fibers separated by loose areolar connective tissue Superior strata is composed mainly of elastic fibersInferior strata is made up mainly by fibrous tissue.The posterior attachment tissues are highly innervated by the auriculo-temporal nerve.The superior surface of the disc is concavo-convex, whereas the undersurface is concave antero-posteriorly.The meniscus (disc) is attached tightly to the medial and lateral poles of the condyle.Posteriorly the attachment is elastic to allow it to translate forward with the condyleAnteriorly, the disc is continuous with the capsule and the lateral pterygoid fascia.

Capsule:Is a ligamentous structureIt extends from the temporal portion of glenoid fossa , fuses with the margins of the disc, reach the neck of condyle to invest the entire joint.It is reinforced laterally by the TM ligament. The temporomandibular ligament:It is composed of horizontal oblique and deep horizontal connective tissue fibers.It reinforces the capsule laterally.It acts to limit anterior and posterior condylar movements.It is designed to prevent the mandible from opening too far on a pure hinge rotation at the uppermost position.As the jaw opens on a pure hinge movement, the floor of the mouth is directed back into the airway.To prevent this the ligament reach its full length at about 15 to 20mm of the jaw opening.At this point, the site of attachment of the TML to condyle becomes a pivot that initiate forward translation of the rotating condyle.This requires the mandible to move forward away from any airway obstruction during full opening.The temporomandibular ligament: Normal function The condyle disc interface of the joint is the site of primary hinge movement.This is made possible by fixation of the disc to condyle by the discal ligaments.Contraction of the inferior lateral pterygoid muscle occurs during opening movement and result in anterior condylar translation.During closure the inferior lateral pterygoid releases contraction to allow the condyle to be pulled back by the elevator muscles.During closure the superior lateral pterygoid activate its contraction to hold the disc forward, to oppose the pull of elastic fibers.The superior lateral pterygoid muscle is essentially passive; contracting during forced closure, or in the presence of occlusal interferences.Centric relation:The relationship of the mandible to the maxilla when the properly aligned condyle-disc assembly is in the most superior position against the eminence, irrespective of tooth position or vertical dimension.Centric Occlusion:The relationship of the mandible to maxilla when the teeth are in maximum occlusal contact, irrespective of position or alignment of condyle disc- assembly.

The Temporomandibular Joint DisordersThe ADA classification of TMJ disorders (developed by Weldon Bell)Masticatory muscle disorders :1. Protective muscle splinting.2. Myofacial pain dysfunction syndrome.3. Muscle hyper activity or spasm.4. Myositis (muscle inflammation)Intra-articular problems: (internal derangement):1. Anterior disc displacement with reduction (clicking).2. Anterior disc displacement without reduction (closed lock)

Degenerative joint disease Arthrosis. Arthritis.

Inflammatory joint disorders: Rheumatoid arthritisInfectious arthritis.Metabolic arthritis.

Functional disorders:Dislocation & subluxation.TMJ Ankylosis.

DIAGNOSIS OF TMJ DISORDERSDiagnosis of TMJ disease or dysfunction depends upon thorough history and clinical examination, plus radiographic imaging. TMJ disease / dysfunction are intimately related to occlusion.History Taking History of the present complaint (onset & course) is taken .Ascertain the effect of function on the symptoms, its relation to daytime and stresses. The general past history including medical, surgical, psychological, occupational, social and family background.

Physical examination Examination of the joint itself.The range of opening anteriorly is measured. Opening, closing, protrusive, and lateral movements are evaluated. Direct examination of the condyles both in the periauricular area and via external auditory meatus (endaural).Sounds whether audible to the examiner or heard by the stethoscope.Palpation of the muscles of mastication for areas of tenderness, rigidity, or masses.Examination of dentition and other hard and soft tissues of oral cavity.Radiographic diagnosisPlain radiography; orthopantomogram (Panoramic x-ray), oblique lateral transcranial views, and transpharyngeal views in the open and closed positions.Tomography; Tomograms offer the best results of plain radiography because of the elimination of superimposition found in conventional radiographs.Tomographic section of TMJ are done with mouth closed and opened.Arthrography; Arthrograms, where radiographs are taken after a radio-opaque dye has been injected into the synovial spaces, can demonstrate the position of soft tissues within a joint by negative image. It has the disadvantage of being invasive.Computed Tomography (CT Scan); It is a non-invasive technique helpful in diagnosis of abnormalities in hard / soft tissue components of the joint

Magnetic resonance imaging (MRI); it is an imaging procedure with vast clinical potential, as it offers detailed views of internal anatomy without ionizing radiation or invasion. More helpful in diagnosis of soft tissue ( disk ) diseases. Arthroscopy; it allows direct visualization .TMJ is a difficult joint for arthroscopy; not only being small in size, but it has two compartments with the line of entry of the instrument from the lateral side shielded by the tip of the root of zygoma. Radiographic diagnosis Ultrasound (US); the wavelengths available for diagnostic ultrasound do not permit visualization of soft tissues in close apposition to bone . Ultrasound in its present form has no value.

Laboratory examination Laboratory examination; such as complete blood cell count, serum calcium, phosphorous, and alkaline phosphatase. Also serum uric acid, serum rheumatoid factor RF. The ADA classification of TMJ disorders (developed by Weldon Bell)Masticatory muscle disorders :1. Protective muscle splinting.2. Myofascial pain dysfunction syndrome.3. Muscle hyper activity or spasm.4. Myositis (muscle inflammation)

Protective muscle splintingThe lateral pterygoid muscles are capable of holding the condyles in an advanced position during protrusive function.The mechanism that forces this prolonged contraction of the lateral pterygoid muscles is sensitive protective reflex system that guards the teeth and their supporting structures against excessive stress. This proprioceptive receptors are designed to program the lateral pterygoid muscle to position the jaw so that the elevator muscles can close directly into maximum occlusal contact. This unique relationship between the lateral pterygoid muscles and the proprioceptive periodontal receptors is so definite that is even override the normal tendency of the muscle to rest when it becomes fatigued. The muscles cannot relax the protective bracing contraction as long as the occlusal interference is present.The pattern of deviation is reinforced every time the contact is made, and it is retained in the brains memory bank (muscle engram) so that muscular closure into the deviated jaw relationship becomes automatic One important fact of the proprio-ceptive memory, however, is that it fades rapidly if continual reinforcement of the pattern ceases.Elimination of interfering contacts permits an almost immediate return to normal muscle function The fatigue or spasm that occur from prolonged hyperactivity often produces pain in the muscle. Sensory nerve endings in the muscles are highly sensitive to lactic acid buildup and also to ischemia. When the nerve endings are stimulated, they report such stimulation as pain. Ischemia can occur in the muscle because of the tight spastic contraction around its own blood supply.Occlusal splints can perform one basic function. They can prevent the existing occlusion from controlling the jaw to jaw relationship at maximum intercuspation by providing a smooth surface, which gives a chance for correcting the position of the condyle-disk assemblies and relief of any spasm in the masticatory muscles.Types of occlusal splints:Soft Occlusal Splint Hard Occlusal SplintPermissive splint: Designed to unlock the occlusion to remove the deviating tooth inclines from contact.Directive splint: Designed to position the mandible in a specific relation to maxilla.

MYOFASCIAL PAIN DYSFUNCTION SYNDROMEIt is not a disease entity rather than a set of etiologically non-related disorders. Normal TMJ / Muscle pain.This explains why this syndrome is defined on the basis of the symptoms rather than on the basis or the principle etiologic factor (cause and effect). MPDS :Signs and symptoms:PainTenderness of the masticatory muscles.Clicking.Limitation of mandibular movements.Absence of clinical or radiographic evidence of organic changes in the TMJ.Lack of tenderness in TMJ on endaural examination.

The Trigger points are signature mark of MPDS diagnosis. By spot palpation of all muscles suspected pain is present.Painful limits of the range of motion of opening. Etiology: Occlusal Disharmony Psychological Disturbance TREATMENT: (it's multidisciplinary)1- Pharmacological line of treatment : - NSAIDS (aspirin, ibuprofen) - Tricyclic anti-depressant drugs in low doses - Potent muscles relaxant (diazepam, skelaxin )2- Injection therapy : into trigger points:a) local analgesic (bupivacaine, lidocaine )b) Skeletal muscle relaxant ( botulinum toxin BO-TOX )as it cuts innervation into muscles. 3- Role of Dentist : Breaking up bad habits (bruxism, clinching, grinding). Treatment of occlusal disharmony / occlusal adjustment.Occlusal splints : Occlusal splints can perform one basic function. They can prevent the existing occlusion from controlling the jaw to jaw relationship at maximum intercuspation by providing a smooth surface, which gives a chance for correcting the position of the condyle-disk assemblies and relief of any spasm in the masticatory muscles.

Types of occlusal splints:1. Soft.2. Hard3. Permissive: Designed to unlock the occlusion to remove the deviating tooth inclines from contact.4. Directive: Designed to position the mandible in a specific relation to maxilla.

4- Improvement of nutrition: - Soft diet - Increase of intake of vitamins 5- Psychological line of treatment : The role of psychiatric specialist will takes place in elimination of stress.

Intra-articular problems: (internal derangement):1. Anterior disc displacement with reduction (clicking).2. Anterior disc displacement without reduction (closed lock)Internal derangementInternal derangement of the TMJ can be defined as a mal-relation of the meniscus to the condylar head and articular eminence.It is categorized as:1. Anterior displacement of the disc with reduction (reciprocal clicking of the joint)2. Anterior displacement of the disc without reduction (locked joint). Anterior disc displacement(With reduction)If the normally secure attachment of the meniscus to the lateral condylar pole is slack or detached.Or if the bilaminar zone has been destroyed or degenerated from trauma or joint disease.As the interincisal opening increases; a spontaneous reduction of the anteriorly displaced disc occurs producing the characteristic click. The origin of the joint click is related to the passage of the condyle over the thick posterior meniscal band. On closure, a subsequent resumption of anterior meniscal displacement occurs, a second click is noted (reciprocal clicking). Anterior disc displacementwithout reduction(closed lock)Closed lock is the result of unreduced, persistent anterior displacement of the disc.When the posterior band of the deformed disc is trapped anterior to the condyle, it forms a mechanical barrier to normal condylar translation. Interincisal opening is seldom greater than 25 mm.Translation is absent.Clicking phenomenon is lost. The condition may progress to perforation of the disc accompanied by osteoarthrosis of the condyle and articular eminence.MRI done for diagnosis.Closed lock.No translation.No clicking.Deformed disc.Painful joint.

Acute closed lockIt is the result of trauma in which the condyle is driven posteriorly with subsequent injury to the posterior attachment. The resultant pain/discomfort may be severe, and the condition is sometimes identified as discitis. It is an inflammation of the discal attachments rather than the relatively avascular/aneural disc itself.

Treatment Of Internal Derangement Of TMJConservative treatmentOcclusal therapy: This line of treatment consists of occlusal splints, occlusal equilibration (selective grinding of teeth) and dental reconstruction.A full occlusal splint harmonized to the most comfortable joint position may produce acceptable results. Physiotherapy !!!.Psychotherapy !!!.

surgical treatmentHigh condylar shave.Eminectomy.Capsular rearrangement.Menisectomy.Subcondylar osteotomy.Meniscoplasty; transaction and plication of posterior attachment.Recently arthrocentesis.ArthrocentesisConsists of anesthezing the affected TMJ with local anaesthetic followed by flushing the joint with a sterile solution such as Lactate ringers solution anti-inflammatory steroids.Used to lubricate the joint surfaces and reduce inflammation.

Degenerative joint diseaseArthrosis. Arthritis.Inflammatory joint disorders:Rheumatoid arthritisInfectious arthritis.Metabolic arthritis.Degenerative (osteoarthritis).Traumatic.It is an inflammatory systemic disease that produces destructive changes, in more than a single joint. Clinically, there is pain, joint noise, and limitation of motion.Obvious distortion of occlusion may be seen Rheumatoid arthritisIn cases of juvenile rheumatoid arthritis (JRA) there is such an extensive damage to the condyle that the growth of the jaw may be seriously impaired by the development of ankylosis. Diagnosis is established by both laboratory and radiographic studiesA positive rheumatoid factor RF, particularly in the presence of multiple joint involvement is fairly decisive in establishing the diagnosis. The condyles are eroded, and flattened. There is narrowing of the joint space . Arthritis urica (Gout)Is a metabolic disease of unknown etiology.The joint tissue may be inflamed owing to deposition of micro crystals of sodium urate.The acute onset is very characteristic.The affected joint is reddened, warm,swollen, and very tender.The pt. Feels ill and fever.Degenerative arthritis(osteoarthritis)It can occur as the result of prolonged functional abuse (closed lock). Diagnosis of Osteoarthritis is made on the basis of clinical & radiographic evidences Sclerosis of the interposed deformed discFacet on antero-superior surface of condyle with loss of corex.Sclerosis of cortex at summit and inferior surface of condyle.Cyst like destruction posteriorlyFlattened eminenceSmall osteophyte on superior surface of the condyle.Sclerosing of the condyle.The intermediate zone and posterior band of the TMJ disc are ill defined.Infectious arthritisBacterial or fungal disease of the joint.It may be due to local extension of infections from the middle ear, mastoid process, parotid gland and mandible. Eventually, fibrous or even bony ankylosis can occur.Traumatic arthritisIt the result of acute direct trauma and not micro-trauma caused by repeated dental function and mechanical stress. Hemarthrosis or traumatic svnovitis may be the major direct effects of trauma to the joints. Dislocation and subluxationDislocation i.e., luxation, is the displacement of condylar head completely out of glenoid fossa anterior & superior to the summit of articular eminence. It occurs when capsule (collateral ligaments) and temporomandibular ligament are compromised. it cannot be reduced by the patient. It may assume a chronic, recurrent form in which patients suffer numerous episodes with resultant abnormal laxity of the supporting capsule and ligaments (chronic subluxation). Reduced by the patient. Etiology: Most dislocations occur spontaneously on opening the mouth widely for yawning, dental work, during seizure.Trauma may also produce dislocation.Clinical findingsUncomfortable but not severely painful.Inability to close the mouth.Dislocations may be unilateral or bilateralPrognathic appearance to jaw when both are dislocated.Deviation of the mandible to the opposite side in unilateral dislocation. Reduction of TMJ dislocationReduction occurs through downward pressure with the thumbs on the external oblique ridges, and upward pressure with the fingers.Treatment of dislocation1- Eminectomy

2- Dautery operation Preauricular incision. The anterior part of the eminence which is attached to the zygomatic arch is exposed.This anterior portion of the eminence is down-fractured.Because of the increase in eminence height, the condyle is unable to dislocate. Other methods of eminence augmentation have been described, for example bone graft augmentation.

TMJ ankylosisAnkylosis is a chronic hypomobility or immobility of movable articulation. It is considered as one of the most common sequelae following infection or trauma. TMJ ankylosisIt has been classified into:*Unilateral or bilateral*True (intra-articular) * False (extra-articular).*Fibrous or bony.*Partial or complete.

CLINICAL FEATURES Inability to open the jaws. In unilateral ankylosis, the lower jaws shifts towards the affected side on opening of the mouth. In severe cases, there is complete immobilization. Facial deformity (Bird Face). Other bones and joints deformities may be associated.TREATMENT:1- Condylectomy Pre-auricular incision. Horizontal cut carried is out at the level of the condylar neck The head (condyle) should be separated from the superior attachment3- Gap Arthroplasty.2- TMJ Interpositional Arthroplasty : Interpositional arthroplasty using buccal pad of fat4- Total Joint Replacement.

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