Articular Disc Disorder of Temporomandibular Joint

The articular disc, commonly referred to as the meniscus, is a fibro-cartilaginous biconcave structure that provides the sliding surface for any mandibular condyle, leading to smooth joint movement. Temporal bone and mandible of different articular surfaces are separated by various articular discs that split the joint cavity into two small spaces. The most common type of internal temporomandibular joint derangement is anterior misalignment or articular disc disorder related to temporomandibular joint.

When the head of the lateral pterygoid muscle pulls the articular disc out of its place interiorly, it may result in abnormal jaw mechanisms leading to spasms. Articular disc disorder of temporomandibular joint can also be due to acquired or congenital asymmetries or due to arthritis or the sequence of trauma. Restricted jaw opening or locked jaw and pain around the ear and the temporomandibular joint may happen because of articular disc disorder. Disorders with reduction may happen in around one-third of the population at some stage of their lives. Any types of articular disc disorders can cause synovitis or capsulitis, which actually results in inflammation of the tissues around any joints, ligaments, tendons, synovium, connective tissue, etc.

Signs and symptoms of articular disc disorders of temporomandibular joint vary in their presentation. The symptoms usually involve more than one of the different components of the masticatory system including nerves, muscles, ligaments, tendons, connective tissue, bones, or the teeth.

• Tenderness or pain on palpation in the muscles of mastication, or preauricular pain in front of the ear. Pain is usually aggravated by functions like clenching, chewing, or yawning, and become worse after waking. The pain is more usually unilateral rather than bilateral, rarely severe, poorly localized, or sometimes become constant.
• Limited mandibular movement, leading to difficulty in talking or eating. There may be stiffness in the jaw joints and muscles, or locking of the jaw. There may also be asymmetry or in coordination of mandibular movement.
• Articular Disc Disorders with reduction often causes a popping or clicking sound when the mouth is opened. Pain usually occurs at the time of chewing hard foods. The maximum opening of the upper and lower incisors is generally reduced from the actual 45 mm-50 mm to ≤30 mm. Sometimes capsulitis results in tenderness, restricted opening, or localized joint pain.

Other signs and symptoms of Articular Disc Disorders of temporomandibular joint have also been described which are less common or less significant than the symptoms listed above.

• Headache, possibly in the occipital region or the forehead. Some other types of facial pain also occur, such as tension headache, myofascial pain or migraine.
• Pain also occurs in the shoulder, neck, or teeth
• Hearing loss
• Feelings of extreme pressure behind the eyes
• Dizziness
• Sensation of the teeth that do not meet parallel together
• Tinnitus also results occasionally.

A recent study has revealed that young women aged 19-40 years have a higher incidence of facing articular disc disorders and the peak age to get this disorder is around 30 years. However, only in 3.6-7% cases faces the severity to seek for medical assistance. Among these, jaw symptoms and facial pain are less frequently seen in African Americans as compared to Caucasians in whom it is observed very frequently. Articular Disc Disorders most commonly affects women with a male-to-female ratio of 1:4 and the symptoms in female are less likely to get resolved.

It has been reported that the natural history of articular disc disorders is self-limiting and benign with symptoms slowly resolving and improving over time. Therefore, the prognosis is quite good. However, the psychological discomfort, persistent pain symptoms, functional limitations, and physical disability may deteriorate the quality of life. It has been found out that articular disc disorders of temporomandibular joint do not lead to arthritis or any permanent damage in the later stage of life, however, degenerative disorders, such as osteoarthritis may occur within the spectrum of the disorder in some cases.

Articular disc disorder articular disc disorders of temporomandibular joint is a symptom that is thought to be caused by multiple factors, but the exact reason is totally unknown. The factors which are responsible for the causing articular disc disorders of temporomandibular joint are listed below:

• Genetic Factors Causing Articular Disc Disorder of Temporomandibular Joint: The variation of the COMT gene which produces less of catechol-O-methyl transferase enzyme is associated with a high chance of getting articular disc disorders resulting in severe pain. Females with this variation, are generally at 2-3 times greater risk of developing articular disc disorders of temporomandibular joint than females without any variant.
• Hormonal Factors: Studies reveal that female sex hormone estrogen can be correlated with the pain involved in articular disc disorders.
• Articular Disc Disorder of Temporomandibular Joint due to Occlusal Factors: Abnormalities of occlusion, i.e., trouble in biting are often associated with the disorder.
• Bruxism: Bruxism is oral para-functional activities that can occur during sleep or when awake. Bruxism and other para-functional activities like lip and cheek biting, pen chewing, nail biting, excessive gum chewing, jaw thrusting, or eating very hard foods may play a role in perpetuating symptoms of articular disc disorders of temporomandibular joint in some cases.
• Degenerative Joint Diseases: Some conditions like rheumatoid arthritis, osteoarthritis, or arthrosis can also cause articular disc disorders of temporomandibular joint leading to defects in the tissues of the joint, limitation of joint function and excessive pain.
• Psychological Issues: Emotional stress, anxiety, anger, depression, and sleep deficiency etc. are thought to be frequently involved in causing articular disc disorders of temporomandibular joint.
• Trauma: Both micro and macro trauma during violent laughing, yawning, sports injuries, road traffic accidents, and dental treatment or interpersonal violence, may lead to muscular hyperactivity or the articular disc disorders of the temporomandibular joint.
• Other diseases such as polyarthritides such as ankylosis, dislocation of joints, neoplasia, infection, and various congenital anomalies may contribute to articular disc disorders of temporomandibular joint.

Pain, tenderness, and mastication muscles spasm experienced are muscular dysfunction and hyperactivity due to malocclusion of variable duration and degree in the joint. Interposition of the posterior band between the condyle and abnormal anterior displacement are responsible for the prominent cause of pops, pain, and crepitus. The characteristic click or pop is caused due to the sudden posterior band reduction. In articular disc disorders of temporomandibular joint, the spasm experienced in the mastication muscle is basically secondary in nature.

Researches have shown that in patients with chronic inflammatory connective tissue disorder, the tenderness on posterior palpation of mandibular joints and the pain on mandibular movement are related to the level of tumor necrosis factor alpha of the synovial fluid. Some studies found that interleukin 1 receptor antagonist and soluble IL-1 receptor II of the synovial fluid and blood plasma of patients with the involvement of polyarthritis have highly influenced the inflammation.

Some of the psychosocial aspects of the disease are also related to the underlying neurobiology. It is seen that the patient diagnosed with articular disc disorders is related to genetic variations with the gene coding for catecholamine-O-methyltransferase (COMT) that is related to some aspects of pain sensitivity.

The probable risk factors associated with articular disc disorders of temporomandibular joint are mentioned in the following points:

• Past jaw locking episodes
• History of Teeth tightening or Bruxism
• Higher levels of depression, anxiety, sleep deprivation, or somatization
• Chronic ticking on jaw movement.

Articular disc disorders have been suggested to be associated with other complications of varying degrees that are listed as follows:

• Obstructive Sleep Apnea
• Systemic joint laxity
• Irritable bowel syndrome
• Interstitial cystitis
• Chronic back pain
• Chronic neck pain
• Mild to severe headache.

Diagnostic criteria for articular disc disorders are as follows:

• Pain in muscles of mastication, or the periauricular area that becomes worse by manipulation or function.
• Irregular mandibular movement with or without clicking.
• Pain present for a minimum of 2-3 months.
• Limitation of mandibular movements.
• When the jaw doesn’t open >10 mm
• Recurrent pain in one or more regions of the face or head
• X-ray, MRI or bone scintigraphy to confirm the presence of a disc disorders
• Evidence that pain is occurring due to one of the following cause:
  • Pain is associated with chewing of hard food or by jaw movements
  • Clicking or popping noise during the opening of mouth or jaw movements
  • Tenderness of the joint capsules.

Treatment for articular disc disorders of temporomandibular joint are directed towards reduction of pain, improvement of muscular dysfunction, and slowing the progression of the disease.

• Non-Surgical Treatment for Articular Disc Disorder of Temporomandibular Joint: Patients with severe pain and joint dysfunction may also be treated non-surgically by utilizing one of the following methods.
  • Diet: In this, any types of non-chewing diet such as liquid food are prescribed. However, the diet may also include semi-solid food if the joint pain improves.
  • Pharmacologic Agents: The non-steroidal anti-inflammatory drugs or NSAIDs are the main form of the pharmacological treatment of musculoskeletal disorders where pain and inflammation are present prominently.
  • Maxillomandibular Appliances: Maxillomandibular appliances like bite guards, occlusal splints, night guards, or orthotics are widely used to control bruxism.
  • Physiotherapy: Physiotherapy together with other methods of treatment for articular disc disorders of temporomandibular joint is used to relieve skeletal pain and muscular spasms and thus helps to improve different range of motions.
  • Injections: Injections in tender muscles, triggering areas, or in joint spaces are used to provide relief from symptoms. Corticosteroid injection is somewhat effective in reducing capsulitis. Botox is used to eradicate muscle spasm and diminish the strength of contraction.
  • Behavior Modification: Behavior or psychological modification is planned to help patients with articular disc disorders of temporomandibular joint to avoid stress-related lifestyle habits like scrunching, bruxism, and excessive gum chewing.
• Surgical Treatment for Articular Disc Disorder of Temporomandibular Joint: Different surgical procedures are quite effective for the treatment of joints with articular disc disorders such as Arthrocentesis, Arthroscopy, Condylotomy, and Arthrotomy.

Few preventive measures of articular disc disorders are as follows:

• Extra oral or mouth guards should be attached to head in the form of a helmet or wire cage.
• Intraoral mouth guards rest should be fitted to maxillary teeth within dental arches, and thus shaped accordingly.
• The risk of luxation and fractures in anterior dentition by direct blows or posterior dentition should be reduced.
• Protection of soft tissues from being shredded by limits of the teeth.
• The possibility of mandibular and maxillary fractures should be reduced by engrossing the impact force.

Early diagnosis of clinical symptoms of articular disc disorders should be routinely examined by specialist or maxillofacial surgeons and neuro-cognitive tests must be carried out on a regular basis. Accordingly, physical, pharmacological, or surgical process should be executed. The medical professional should make efforts to advise the use of mouth guards by offering active preventive measures in order to reduce this type of incidence further.

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