TEMPOROMANDIBULAR JOINT

TEMPOROMANDIBULAR JOINTDr Bhaumik ThakkarMDS-Part 1.Dept. Of Periodontology and Implantology.

INTRODUCTIONThe most important functions of the temporomandibular joint (TMJ) are mastication and speech and are of great interest to dentists, orthodontists, clinicians, and radiologists.

The TMJ is a ginglymoarthrodial joint, a term that is derived from ginglymus, meaning a hinge joint, allowing motion only backward and forward in one plane, and arthrodia, meaning a joint of which permits a gliding motion of the surfaces.

Temporomandibular joint

Only mobile joint of skull formed between head of mandible and articular fossa of temporal bone.

Peculiarity of TMJBilateral diarthrosis right & left function together

Articular surface covered by fibrocartilage-instead of hyaline cartilage

Only joint in human body to have a rigid endpoint of closure (that of the teeth making occlusal contact).

In contrast to other diarthrodial joints TMJ is last joint to start develop in- about 7th week in utero.

Develops from two distinct blastema. i) Temporal. ii) Condylar.

T- 1st to develop C-rapid growth in dorsolateral dirctn. Blastema is mass of cells for grwtn n regnrtn of body parts.5

LigamentsFibrous capsuleArticular discLateral ligament of jawSphenomandibular ligamentStylomandibular ligament

Fibrous capsuleAbove to the anterior edge of the preglenoid plane.

Posteriorly to the squamotympanic fissure, between these to the edges of the articular fossa.

Below to the periphery of the neck of the mandible.

Squamotympanic-seperates tympanic part or temporal from squamous part.7

Articular discFibrocartilaginous disc dividing joint cavity in upper and lower compartment.Shape: OvalMakes articular surface congruent.In sagittal section- a thin intermediate zone and thickened anterior and posterior bands, and its upper surface appears concavo-convex. Posteriorly- Attached to a region of loose vascular and nervous tissue which splits into two laminae, the bilaminar region.

Congruent is same shape n size. 8

Functions of Articular disc Stabilize the TMJ.

Makes articular surfaces congruent.

Reduce wear of TMJ.

Aid lubrication of the joint.

Lateral ligament of Jaw Attached above to the articular tubercle on the root of the zygomatic process of the temporal bone. It extends downwards and backwards at an angle of 45 to the horizontal, to attach to the lateral surface and posterior border of the neck of the condyle, deep to the parotid gland.Function: To prevent posterior displacement of the resting condyle.

Sphenomandibular ligamentMedial to, and normally separate from, the capsule. It is a flat, thin band that descends from the spine of the sphenoid.

Widens at the lingula of the mandibular foramen. This part is a vestige of the dorsal end of Meckel's cartilage.

It is separated from the pharynx by fat and a pharyngeal vein.

Meckels cartilage-cartilaginous bar of mand. arch12

Stylomandibular ligament

A thickened band of deep cervical fascia that stretches from the apex and adjacent anterior aspect of the styloid process to the angle and posterior border of the mandible.

Along with sphenomandibular ligament it is responsible for limitation of mandibular movement.

Limits excessive opening.14

Blood supply & Innervation

Auriculotemporal nervemaxillary arteryMasseteric nerveSuperficial temporal arteryArterial supply : Superficial temporal artery laterally and the maxillary artery medially.Nerve supply: Masseteric and auriculotemporal nerves

STA- arises from ext carotid art. Supllies blood to scalp. Masseteric from mand.nerve innervates masseter and tmj. Auriculo from mand nerve innervates side of head.15

VASCULARIZATIONPredominant vessals supplying tmj are:

Superficial temporal artery from the posteriorMiddle meningeal artery from the anteriorInternal maxillary artery from the inferior

HISTOLOGY OF ARTICULAR SURFACE OF TMJ

The Articular zoneDense fibrous connective tissuePoor blood supplyBetter ability to repair Good adaption to sliding movementShock absorberLess susceptible to the effect of aging time & breakdown over time.

Collagen fibers are less susceptible than hyaline cartilage to the effect of ageing and therefore less likely to breakdown over time.

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2. The proliferative zone

Mainly cellular zoneUndifferentiated mesenchymal cellsProliferation & regeneration throughout life

3. The cartilagenous zoneCollagen fibers arranged in criss -cross pattern of bundlesFibrocartilage appears in a random orientation, providing a three-dimensional network that offers resistance against compressive and lateral forces.

Offers considerable resistance against compressive & lateral forces

But becomes thinner with age.

4. The calcified zone

Deepest zoneChondrocytes, chondroblasts & osteoblasts

Active site for remodeling activity as bone growth proceeds.

Movements of TMJRotational / hinge movement in first 20-25mm of mouth opening

Translational movement after that when the mouth is excessively opened.

Muscles involved in movement.DepressionLateral pterygoid, Digastric, Geniohyoid, Mylohyoid.ElevationTemporalis, Masseter, Medial pterygoid.ProtrusionMedial pterygoid, lateral pterygoid.RetractionPosterior fibres of temporalis.

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Age changes of the TMJ:Condyle:Becomes more flattenedFibrous capsule becomes thicker.Osteoporosis of underlying bone.Thinning or absence of cartilaginous zone.

Disk:Becomes thinner.Shows hyalinization and chondroid changes.

Synovial fold:Become fibrotic with thick basement membrane.

Blood vessels and nerves:Walls of blood vessels thickened.Nerves decrease in number

Age changes lead to:Decrease in the synovial fluid formation

Impairment of motion due to decrease in the disc and capsule extensibility

Decrease the resilience during mastication due to chondroid changes into collagenous elements

Dysfunction in older people

Symmetrical opening Associated with preparation for incising.

At the start, each mandibular condyle rotates in the lower joint compartment inside the annulus of its disc. After a few degrees of opening, the condyle continues rotating inside its disc, and, in addition, both slide forward down the articular eminence of the upper joint compartment.

Without this forward slide, it rapidly becomes impossible to continue opening the jaw.

Annulus-ring like anatomical parts27

Eccentric jaw openingPreparation for power stroke of mastication.

Condyle on the non-working side slide back and forth during lateral movements.

Temporomandibular and Sphenomandibular ligament keep condyle firmly against articular eminence.

Eccentric and symmetrical jaw closingJaw closing muscles have a component of force that forces joint surfaces together.

Joint tissues compressed- ligaments shortened- no constraint on movements.

Non-working condyle moves further and is most heavily loaded during power stroke.

Jaw close-masseter temporalis medial ptery.29

Temporomandibular Joint Disorder

Various terms have been used to describe disturbances of the masticatory system.

1934 James costen described group of symptoms centering around ear and TMJ- Costen syndrome.

1959 Shore introduced TMJ Dysfunction

Ash & Ramfjord- functional TMJ disturbances

Terminology

Costen synd- loss of hearing tinnitis dizziness headache etc. Mandibular joint neuralgia.31

Limited nature of these terms lead to a broader term- Craniomandibular disorders.

Bell coined the term Temporomandibular disorders.

Describes both problems associated with the joint & disturbances associated with function of masticatory system.

Problems in chewing muscles and associated struc.32

EventEvents can be either local or systemic.

Local: a change in proprioceptive input e.g improper crown.

Can be secondary to trauma- too wide opening of mouth; unaccustomed use- bruxism.

Proprio- realted to stimuli.33

Also deep pain input- alters muscle function by way of central excitatory effects.

Systemic events; that alter normal function occurs at a systemic level; emotional stress.

Central excitatory- exciatatory and depressant effect of pilocarpine due to direct central acion of drug.changes in pH,plasma co2 etc.34

Physiologic toleranceInfluenced by local and systemic factors.Local: orthopedic stability-relation between mandible and maxilla- good stability; mandible closes with the condyles in their most superior and anterior position against posterior slopes of articular eminence- even contact of all possible teeth. Here masticatory system is best able to tolerate local and systemic events.

Poor stability: one way by which occlusal condition influences symptoms associated with TMD.

Instability can be in occlusion/joints/both.

Can be genetic/developmental/iatrogenic. Also related to alterations in normal anatomic form.

Systemic: multiple systemic factors influence physiologic tolerance; genetic/gender diet/chronic & acute diseases.

Etiologic considerations for TMD.5 major factors associated with TMDOcclusal condition:TraumaEmotional stressDeep pain inputPara-functional activities.

Occlusal conditionExcessive load on the system due to orthopedic instability may lead to intracapsular disorders.2 factors that determine it are: degree of instability and amount of loading.Changes can be acute/ sudden or chronic.

TraumaMacro and micro

Macro: sudden face that can result in structural alterations. Eg blow to face.

Micro : small force applied repeatedly to structures over a long periods. Bruxism/ clenching.

Deep pain input.Centrally excites a brainstem produces muscle response- protective co-contraction.

Functional disorders of masticatory system 2 symptoms: Pain and dysfunction.

In case of presence of pain. Evaluated based on chief complaintQuestions askedChief complaint.Location of pain.Onset of pain.Associated factors.Progression.

C. Characterstics of painQuality Behavior Temporal Duration Localization.3. Intensity of painConcomitant symptoms.Flow of pain.

D. Aggrevating and alleviating factorsFunction and parafunctionPhysical modalitiesMedicationsEmotional stressSleep disturbancesE. Past consulations or treatment

II Medical historyIII. Review of systems

Interpretation;0- no pain or tenderness1- uncomfortable on palpation2- definite discomfort3- eye tearing/ extreme discomfort

Tmj palpation : digital palpation of joint with mandible in both static and dynamic positions.

Finger tips are placed over the lateral aspects of joint areas- lateral poles of condyles passing downward and forward felt.

joint sounds: Clicks / crepitation

Crepitation- crackling sound.46

Click is a single sound of short duration; if relatively loud referred to as POP.

Crepitation multiple gravel like sound grating and complicated

Can be done using digits / stethoscope.

TMJ DISLOCATIONThe mandible can dislocate in the anterior, posterior, lateral, or superior position. Anterior dislocations are the most common These dislocations are classified as acute, chronic recurrent, or chronicTMJ dislocation may occur with trauma, extreme opening of the mouth during yawning, laughing, singing, vomiting, or dental treatment . Symmetric mandibular dislocation is most common, but unilateral dislocation with the jaw deviating to the opposite side also can occur.TMJ dislocation is painful and frightening for the patient.

TMJ DISLOCATION.

TMJ ANKYLOSISAnkylosis of the TMJ most often results from trauma or infection.True bilateral congenital ankylosis of the TMJ leads to micrognathia or bird face. If ankylosis affects only one side, it produces a lateral deviation of the jaw to the non-affected side, due to the fact that this side continues its growth normally.

LAB INVESTIGATIONS1.Blood tests: ESR, CRP for inflammation.2.Plain radiographs - show gross bony pathology such as degeneration or trauma.3.CT or MRI scan of the joint. MRI scan shows the soft tissues and intra-articular disc well.4.Ultrasound - this is a useful alternative imaging technique for monitoring TMJ disorders.5.Diagnostic nerve block.6.Arthroscopy.

Esr is erythrocyte sedimen rate reveals inflammatory act. Crp is c reactive protein for inflammation.51

Management.

Conservative reversible therapy. CounselExercisePhysical therapyMedicationsAppliancesSelective Grinding

Non conservative irreversible therapy.High CondylectomyMeniscectomyDisectomyOrthodontic surgeryHigh CondylotomyHyaluronic acidReconstructionArthrocentisis

Long term studies for TMD treatment have given 2 kinds of approaches ;

Meniscectomy- removal of torn meniscus(thin fibre cartilage betwn joints) arthrocentisis-joint aspiration. For arthritis gout etc53

Definitive treatmentOcclusal conditions- occlusal therapy(occlusal splint)

Reversible-stabilization appliance

Irreversible selective grinding, restorative procedures.

Emotional Stress: Restrictive use, Voluntary avoidance, Relaxation therapy.

Supportive therapyDirected toward the reduction of pain and dysfunction.Pharmacologic or Physical therapy.

Pharmacologic:AnalgesicsNSAIDsCorticosteroidsMuscle relaxantsAntidepressants.

Analgesic-Aspirin,tylenol. Nsaid-ibuprofen, naproxen corticosteriod-omnacortil muscle rela-diazepam antidepp-anxit .25mg55

Physical therapy. Group of supportive actions, usually instituted as an adjunct to definitive treatment. 2 types- Modalities & Manual techniques

Modalities: Thermotherapy, ultrasound, phonophoresis, iontophoresis, laser

Manual techniques: provided by physical therapist; 3 types- soft tissue & joint mobilization, muscle conditioning.

Temporomandibular joint surgery: what does it mean to the dental practitioner

In March 2011, G Dimitroulis in vincents hospital melbourne assesed why dental practioners should be aware of benefits and risks of TMJ surgeries.They concluded that all dental practitioners should be aware of the benefits of TMJ surgery so that patients do not suffer unnecessarily from ongoing non-surgical treatments that ultimately prove to be ineffective in the management of their condition.

Temporomandibular joint problems and periodontal condition in rheumatoid arthritis patients In December 2011, Garib BT1 and Qaradaxi SS in College of Dentistry, University of Sulaimani, Kurdistan assesedTemporomandibular joint problems and periodontal condition in rheumatoid arthritis patients in relation to their rheumatologic status.They took plaque index, bleeding index, clinical attachment loss, radiographic bone loss, tooth loss, and TMJ problems were assessed in the 2 groups.They concluded that Patients with advanced RA are more likely to develop more significant periodontal and TMJ problems compared with patients with PD and without RA. There is a great need to instruct patients with RA to consult a dentist to at least decrease PD severity.

CONCLUSIONIt is impossible to comprehend the fine points of occlusion without an in depth awareness of anatomy ,physiology ,and biomechanics of the TMJ.

The first requirement for successful occlusal treatment is stable, comfortable TMJ.

The jaw joints must be able to accept maximum loading by the elevator muscles with no signs of discomfort.

It is only through an understanding of how the normal, healthy TMJ functions that we can make sense out of what is wrong when it isn't functioning comfortably.

This understanding of TMJ is foundational to diagnosis and treatment.

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