Diseases of the temporomandibular joint

Surgical anatomy The temporomandibular joint consists of

glenoid fossa on the skull base, the condyle, the articular disk separating the fossa and the tubercle, a capsule, and ligaments connected to the capsule. Both the glenoid fossa and the condyle are covered by hard, fibrotic, cartilaginous tissue, which is the thickest deep in the fossa.

The condyle of the mandible is cylindrical, it becomes narrower in the posterior direction, its greatest diameter, in the mediolateral direction is about 2 cm. With a narrow neck, it passes through into the condylar process.

It was earlier believed that the cartilaginous surface covering the condyle behaved as the epiphyseal plate, and that the growth centre of the mandible was situated here. It has recently been proved, however, that the growth of the capitulum is a function of the functional matrix surrouning it. This functional matrix involves the joint function of the articulation, the masticatory muscles and the soft tissues. If some restraining effect is experienced anywhere in the matrix, the condyle and also the whole of the mandible undergo a retardation of growth.

Surgical anatomy From a side view the articular disc

covering the mandibular condyle is like a biconcave cap. The joint space is divided into an upper and a lower compartment. The disk consists of dense, fibrotic, cartilaginous tissue.

The capsule of the articulation joint is supported by temporomandibular, stylomandibular and sphenomandibular ligaments. The last has an important role as a surgical indicator, for the maxillary artery and the auriculotemporal nerve run between the mandibular neck and the sphenomandibular ligament.

The blood supply of the condyle is ensured from the superficial temporal artery and the branches of the maxillar artery

Diagnostic imaging procedures Diagnostic imaging procedures relating to the TMJrelating to the TMJ

Many types of diseases can affect the TMJ, but the location and structure of the normal TMJ mean that it is extremely difficult to examine it with some imaging system. At present however numerous devices and methods are available that can help to get the diagnosis.

Diagnostic imaging procedures relating to TMJ

Conventional X-ray techniques

Panoramic X-ray techniques

arthrography Computer tomographic

imaging (CT) 2-3D Magnetic resonance

imaging (MRI) arthroscopy

Functions of TMJ The TMJ is the only

paired joint in the body that performs its functions in a syncronised and coordinated way.

It functions are influenced by three fundamental factors – Anatomic structure

of the TMJ– Neuromuscular

mechanism– Dental occlusion

The functions of TMJ As a result of the hinge movement, the mouth opens

about 20-25 mm, in consequence of combination of rotating and gliding movements, the distance rises to 35-45 mm.

The rotation is produced by the contraction of the anterior belly of the digastric muscle and the geniohyoid muscle

Sliding in the anterior direction is mainly due to the lateral pterygoid muscle

Sliding to posterior direction depends on the functions of the deep fibers of the masseteric muscle and the posterior fibres of the temporal muscle

Parts are played in the closure by the paravertebral muscles and by the stylohyoid, geniohyoid and infrahyoid muscles. The most important roles are played by the masseteric muscle and the medial pterygoid and temporal muscles.

Temporomandibular disorders

Keith classification Congenital and acquired growth

disturbances Infections Ankylosis Traumatic laesions Dislocation (luxation) Internal derangement Degenerative diseases Tumors

Congenital growth disturbances Unilateral disorders Hemifacial microsomiaHemifacial microsomia is unilateral hypoplasia or

aplasia of the TMJ, it is an asymmetric, progressive deficiency which relates to both soft tissues and the bony sceleton of the scull. The developmntal problem of the first and second branchial arches can cause this disease.

It is classified in three groups– Type I. :”minimanbible” All parts of

the mandible are present and the arch is normal, but they are small

– Type II.: Small and anomalously arched ramus, and hypoplastic, anteriorly and medially situated condyle

– Type III.: total unilateral absence of the condyle and ramus

Congenital grows disturbances

Bilateral developmental anomalies of the first and second branchial arch– Treacher Collins syndrome (mandibulofacial dysostosis)

It is characterized by a bilateral hypoplastic TMJ a short ramus and a decreased face height. This syndrome is a dominantly inherited abnormality. Its rate of occurance is 1:10000. Clinical appearance is always bilateral. Retractions may be observes on eyelids, the lower eyelashes may be missing. The external ear is hypoplastic, hearing disturbance exists.

Acquired TMJ deformities Condylar hyperplasia

– It is the most frequent postnatal abnormality of TMJ . It appears in the years before puberty.

– It is assumed that the cause of the changes lies in the more active metabolism of the condyle

– Two different growth tendencies may be distinguished

Vertical The mandible grows mainly in vertical direction, which results vertically long ramus and body.

Rotational Besides the enlarged condyle and vertically long ramus, the convex enlargement of the body leads to a crossbite and mouth opening deviation. The enhanced metabolism may be proved by bone scintigraphic examination.

Infections Before the advent of antibiotics, infectious

diseases of the TMJ were much common than today. Description from the 19th and 20th centuries revealed that infections of the ear and teeth often spread to the joint. The primary causes of TMJ were infectious diseases of childhood (scarlet fever, chickenpox, diphteria, etc.)

Symptoms:– Intense pain– The most comfortable position for the patient is the

opened mouth – Oedema, erythema above the joint, than

fluctuation– The cronic state was indicated by a fistula in the

region of TMJ.

Ankylosis

 There is a lot of expression, which means the disability of the movement of TMJ– trismus, – pseudoankylosis,– ankylosis.

Trismus: This is an anomaly based on muscle spasm.– Extracapsular process, the TMJ itself is not

effected. Classic examples of the lesion are the complications that arise in the course of conduction anaesthetization. (infection, bleeding or nerve damage)

Pseudoankylosis: – Intraarticular cause: fibrosus ankylosis. – Extraarticular cause: Include the hyperplasia of

the coronoid process or its unification with the maxillary tuber or with the zygomatic bone, or a fractured zygomatic arch. It may occur as a chronic scar contracture of the temporal muscle as a consequence of irradiation or surgery.

Ankylosis: This is a bony unification of the condyle and the glenoid fossa.

Ankylosis Etiology:

– Trauma– Rheumatoid arthritis– Infection– Tumors

In childhood there are a lot of vessels in the joint, which runs between the condyle and the capsule. In the event of trauma haemarthrosis will develop, which undergoes ossification.

In adulthood 51% of the cases of polyarticular rheumatoid arthritis affect the TMJ. ( usually only one) In childhood, the most serious consequece of ankylosis caused by RA is the facial deformity due to the damage to the growth centre. The development of the lower third of the face is retarded and a „birdface” results.

AnkylosisAnkylosis

Infections:Infections: This is now rare as a This is now rare as a cause.cause.

Tumors:Tumors: Are similary rarely observed Are similary rarely observed in the TMJin the TMJ

Diagnosis

History Panoramic

X-ray 3D CT

imaging

Treatment In childhood there are 4 groups in ankilosys and

the treatment vaies group to group, – 1.On the X ray the articular gap is narrowed,

but it can be followed. – 2.The lateral parts of the articular surface

there are much more synostosis but on the medial deeper parts of the TMJ the cartilaginous surfaces are preserved and the disk may be distinguished

– 3. There is a bridge-like synostosis between zygomatic arch and ramus of the mandible. The medial part of the capitulum is intact and able to function.

– 4. The extent of synostosis is such that the TMJ can no longer be recognized.

TreatmentTreatment

The first step in treatment is surgery. The first step in treatment is surgery. The TMJ is usually exposed from The TMJ is usually exposed from preauricular incision. preauricular incision.

In cases belonging to the first two In cases belonging to the first two groups the TMJ can be easily groups the TMJ can be easily recognised after exposure. recognised after exposure.

After closure and postoperative After closure and postoperative period the second step is functional period the second step is functional treatment. treatment.

Treatment

In adulthood– To avoid

reossification some „interposit” is recommended between the reformed articular fossa and condyle. This may be the temporal muscle, cartilage or alloplastic material.

Injuries Dislocation takes place most often in the anterior direction, the

condyle becomes positioned in front of the articular tubercule. Subluxation- The dislocatio is not complete, the condyle can

return to the glenoid fossa Recurrant luxation - The luxation or subluxation occurs on a

number of occasions but there is no psychological factor inducting compulsive movement.

Habitual luxation is coused by compulsive movements. The terms luxation, distorsion and dislocation are used when the

articular surfaces are totally separated from one another and the joint is fixed in this extraarticular position. It may be induced by an external ( hit, extraction) or an internal action (huge yawn, vomiting, singing, dental procedure).

The direct cause of spontaneous luxation is sudden disturbance of the coordination of the muscles movement.

Symptoms

The patient cannot close his or her mouth

The mandible is elastically fixated

The articular fossa is empty Moderate pain in the joint

TreatmentTreatment Acute, chronically persistent, recurrent and habitual

luxation demand different modes of treatment Acute: Reposition- The earlier the repositioning is

attempted the more easily succedes. The thumbs are wrapped in gauze and placed on the occlusal surface of the mndibular molars or alveolar ridges. By pressing firmly on the molars and elevating anteriorly with simultaneous backward pressure, the condyle is relocated.

Chronically persisting luxation: Reposition under general anaesthesia, when the reposition is unsuccessful, condylectomy may be considered

Recurrent: The reposition is generally easy but it is difficult to avoid repetition of the luxation. Conservative or surgical treatment.

Habitual: It is difficult to know how to alter psychological component that includes the compulsive movement.

Internal derangement

 The internal derangement means intracapsular damage of the TMJ which primary arises from the incorrect movement of the articular disk together with the secondary changes of movement. The disease does not belong to developmental anomalies or to other diseases of the TMJ.

Internal derangementInternal derangement

The healthy articular disc allows the appropriate distance between the condyle and the glenoid fossa

Firstly the articular disc displaces, the posterior fibers of the disc becomes loosened, the condyle will be posteriorly positioned

Internal derangement

A further change occure if the disc streches and becomes thinner and the articular gap is reduced progressively in both posterior and anterior direction

The following step is the rupture of the disc, so the glenoid fossa and the condyle come into direct contact

The condyle slowly becomes pointed in the anterior and posterior direction and finally degenerative changes occur in the bone

Internal derangement

Symptoms

pain, deviation, repeated clicking when the mouth is opened and reciprocal clicking when closed

Treatment is primary conservative and only rarely surgical

Medication: NSAID, night bite guard (bite raising appliances)

Degenerative diseases

Osteoarthrosis (arthrosis deformans, osteoarthritis).– It is a non-inflammatory degenerative diseases which mainly

affects the articular surfaces but it also induces reconstruction of and changes in the bone beneath the articular surface.

– Symptoms: Pain, crepitation, restriction of articular movement

 Rheumatoid arthritis– Autoimmune disease of the small periferial joints. In women it

is three times common than in men. In 10-15% of the cases involve a progressive variant with articular destruction and deformities. The inflammation of the synovial membrane is carasteristic. The inflammatoric process damages the joint and the scar tissue impedes the movements.

– Symptoms: Intermittent pain, swelling and progressive restriction of the articular movement. Typical that the small joints of the hand and foot become involve first.

Gout This is a metabolic disease, uric acid

crystals are deposited in and around the joints and these causes inflammatory symptoms. Above the joint the skin is red and swollen and in particular movement gives rise to pain.

Other degenerative diseases– Spondylitis accompanied by ankylosis It

differs from RA that here primarily the ligaments around the joint undergo calcification and osification.

– Psoriatic arthritis: symmetric polyarthritis and negative rheumatoid factors

– Posttraumal arthritis: Arthritis may develop as a consequence of trauma

– Condyle resorption: after bilateral condyle fracture or as a consequence of otitis media

Treatment Conservative -pain killers -normalisation of the occlusion -interocclusal plates -sedatives -steroid intraarticulary Surgical - condylectomy - arthroplasty

Degenerative diseases

Tumors of TMJ  The tumors of TMJ are very rare. These

could develop from some parts of the joint or may spread from the environment of the joint.

Benign tumors The condyle may be enlarged for many reasons, e.g.:– acromegalia, – fibrosus dysplasia, – condylar hypertrophia,– osteoma, osteochondroma, – chondroma stb.

Common typical symptoms:– Slow restriction of the movement of the joint– Painless swelling in the region

Metastases Primer tumor could

be in – prostata, – breast, – kidney, – malignant

melanoma, – lung, – pancreas – etc.

Thank you for your attention!