Temporomandibular Disorders Quiz

Temporomandibular Joint (TMJ) Disorders

• The TMJ is a bilateral synovial joint formed by the articulation of the temporal bone and the mandibular condyle.
• Temporomandibular disorders (TMDs) encompass a range of problems involving the masticatory muscles, the temporomandibular joints, and associated structures.

Learning Outcomes

• Define the TMJ
• Classify TMJ diseases
• Assess TMJ
• Manage TMJ disorders

Functional Anatomy of the TMJ

• The TMJ exhibits hinge and gliding movements.
• The fossa and eminence develop fully by the second decade.
• Condylar rotation is more significant for mouth opening than translation.
• Synovial fluid facilitates lubrication (weeping lubrication).
• Fibrocartilage covers the articulating surfaces.

Articular Disc

• The articular disc is composed of dense collagen fibers.
• It fills the space between the fibrocartilage coverings of the condyle and mandibular fossa.
• The disc is primarily avascular and has limited sensory nerve innervation.
• The disc attaches to the medial and lateral aspects of the condyle
• The disc consists of anterior and posterior bands, thickest in the intermediate zone.
• Fibers from the temporalis, masseter, and lateral pterygoid muscles insert into the anterolateral and anteromedial two-thirds of the disc.

Retrodiscal Tissue

• Retrodiscal tissue is soft tissue positioned behind the disc and condyle, often referred to as the posterior attachment.
• A superior lamina connects the posterior band of the disc to the squamotympanic fissure and tympanic part of the temporal bone.
• An inferior lamina connects to the inferior margin of the posterior slope of the condyle.

TMJ Ligaments

• Capsular ligament
• Lateral temporomandibular ligament
• Sphenomandibular ligament
• Stylomandibular ligament

Muscles of Mastication

• Mandibular movements toward tooth contact are driven by masseter, temporalis, and medial pterygoid muscles.
• Masseter forms a sling that generates significant forces for chewing.
• The masseter muscle, with superficial and deep heads, elevates the mandible.
• Temporalis muscle has anterior, middle, and posterior segments, inserting into the coronoid process and anterior aspect of the mandibular ramus.
• Medial pterygoid muscle, with superficial and deep heads, participates in jaw movement and excursion.
• Lateral pterygoid muscle helps in jaw protrusion and lateral movement.

Other Muscles Related to TMJ Function

• Contraction of the anterior belly of diagastric muscle results in mandible depression.
• Mylohyoid and geniohyoid muscles contribute to mandibular depression.
• Buccinator assists in cheek positioning during chewing.

Vascular Supply of Masticatory System

• The external carotid artery bifurcates into superficial temporal and internal maxillary arteries at the level of the condyle.
• These arteries supply the masticatory muscles and the TMJ.

Nerve Supply of Masticatory System

• The mandibular division of the trigeminal nerve provides motor innervation to mastication muscles.
• The auriculotemporal nerve innervates the TMJ.
• Deep temporal and masseteric nerves supply the anterior part of the joint.

Anatomy of Clinical Interest

• Jaw jerk reflex is a monosynaptic reflex of jaw closing muscles.
• Jaw opening reflex inhibits jaw closing muscles.
• Rest position / centric relation is the maxillomandibular relationship where each condyle articulates with the thinnest portion of the disc against the posterior slope of the articular eminence.
• The mandibular range of motion includes rotation and translation of the condyle and varies in individuals.
• Articular covering is thickest at areas with greatest functional load.

Disc Displacement

• Injury to the inferior lamina of posterior attachment is considered a cause of disc displacement.
• The angle of mandibular fossa might contribute to intra-articular disorders and chronic subluxation or dislocation of the condyle.
• Disc adhesions in the fossa could cause acute closed lock syndrome.

Clinical Tests for TMJ Assessment

• Muscle palpation
• Jaw jerk reflex
• Electromyography (EMG) activity
• Identifying the silent period

Joint Noises and Nerve Entrapment

• TMJ clicking might be due to condylar hypermobility, lateral pole enlargement, intra-articular bodies, and dysfunctional movement patterns.
• Nerve entrapment can occur.

Ear Symptoms Associated with TMDs

• Possible symptoms include earache, tinnitus, and fullness, or feeling of stiffness.

Etiology, Epidemiology, Classification of TMJ Disorders

• Etiology includes premature occlusal contacts, masticatory muscle hyperactivity (bruxism and parafunction), psychological distress, trauma, and rheumatic disorders.

• Prevalence of TMJ disorders is higher in women between the ages of 20 and 40 years.

• Classification is based on the taxonomy of joint disorders, disc disorders, masticatory muscle disorders, and associated structures.

Diagnostic Imaging

• Plain film radiography
• Plain film tomography
• Arthrography
• CT scan
• MRI
• Single photon emission CT
• Radioisotope scanning

Diagnostic Local Anesthetic Nerve Blocks

• Injections in the TMJ, masticatory muscles, or trigger areas.

Prediction of TMD Chronicity

• Pain that extends beyond a certain period.
• Pain persisting beyond usual healing time.
• Pain not responding to usual treatment.

General Principles of Treating TMDs

• Patient categorisation (remission, recurring, persistent symptoms).
• Implement surgical intervention.
• Use relaxation and cognitive behavioral therapy (CBT).
• Consulting a specialist when necessary.

Specific Disorders and their Management

• Myalgia and Myofascial Pain - Education, self-management, physiotherapy (active/passive modalities).
• Instructions to patients for self-care.
• Intra oral appliances (splints, orthotics).
• Pharmacotherapy (NSAIDs, muscle relaxants).
• Behavioral therapy (relaxation techniques, biofeedback, hypnosis).
• Trigger point therapy, injections of local anesthetic.
• Restorative dental procedures.

Intra Oral Appliances

• Splints, orthotics, night guards, bite guards.

Articular Disc Disorders

• Abnormal relationships between the disc, condyle, and articular eminence.
• Common disc displacement is anterior and medial.
• Classified based on signs, symptoms, (e.g., ADD with/without reduction, intermittent locking) and diagnostic imaging.

Types of Disc Displacement

• Anterior disc displacement with reduction
• Anterior disc displacement without reduction
• Posterior disc displacement

Temporomandibular Joint Arthritis

• Degenerative joint diseases involve cartilage and subchondral bone, with secondary synovial membrane inflammation.
• Risk factors include gender, diet, genetics, and psychological stress.
• Presentation can include joint space narrowing, irregular joint space, flattening of articular surfaces, osteophyte formation, and anterior condylar lipping.

Other Types of TMJ Disorders

• Rheumatoid arthritis (primarily affecting periarticular tissue then bone, bilateral involvement, morning stiffness)
• Synovial chondromatosis (rare, cartilage nodules, progressive swelling)
• Septic arthritis (infection)
• Developmental disturbances (hyperplasia, hypoplasia, agenesis)
• Fractures (trauma)
• Dislocation
• Ankylosis (fusion) (bone fusion)

Sleep Bruxism

• Oral appliance therapy,
• Selective serotonin uptake inhibitors,
• Botulinum toxin

Oral Dyskinesia and Dystonia

• Abnormal, involuntary movements of tongue, lips, and jaw.
• Often related to poor fitting dentures associated with lack of replacement of teeth (important to manage).
• Emphasize management, including Botulinum toxin and neurosurgery.