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Temporomandibular Joint Disorders

Dr. Sonia BhattBDS

April 29, 2020

April 29, 2020

Temporomandibular Joint Disorders
Temporomandibular Joint Disorders

A joint is a connection between two bones in the body. Our joints are responsible for giving our body structure and for allowing a whole range of movements. The joints of the body can be divided into structural joints and functional joints.

  • Structural joints: These are further divided into three types of joints, on the basis of their structure:
    • Fibrous joints: These joints are not flexible at all and are found in bones such as the upper jaw, rib cage, backbone, and pelvic bone. 
    • Cartilaginous joints: These joints are partially flexible and are majorly seen in childhood between two bones that help in the growth of the body.
    • Synovial joints: These joints are present in most of the body. They help us perform a wide range of activities such as walking, running and even typing. Synovial joints are present in the wrist, knee, neck and shoulder. The temporomandibular joint is also a synovial joint.
  • Functional joints: These are further divided into six kinds of joints, based on the type and degree of movement they allow:
    • Pivot joint: This type of joint allows sideways and back-and-forth movement. For instance, a pivotal joint is present in the neck.
    • Hinge joint: Hinge joints are like door hinges - they provide only back and forth movement. Hinge joints are present in the ankle, elbows, temporomandibular joint and knee joints.
    • Saddle joint: Saddle joint allows two movements, bending and straightening of the joint and abduction/adduction of the joint (moving towards and away from the midpoint of the body, respectively). The thumb is the only bone in the body that has a saddle joint.
    • Gliding joint: Gliding joints are the most common type of synovial joint as they allow two or more round or flat bones to move freely together without rubbing or crushing each other. A gliding joint is seen between the lower leg and the ankle and also between the forearm and wrist.
    • Ball and socket joint: In this joint, as the name suggests, the round head of one bone sits into the hollow space of another bone to provide the rotatory movement. Shoulders are a classic example of a ball and socket joint.
    • Condyloid joint: Condyloid joints allow up-down and side-to-side motions. The condyloid joints are found at the base of the index finger, elbow and the wrist. 

The temporomandibular joint (TMJ) is the most used joint in the body. The temporomandibular joint works when you talk, eat, even open and close your mouth. The TMJ is the joint between the temporal bone, present at the base of the skull, and the condylar head (ball-shaped head) of the mandible (lower jaw bone). A disc, known as the articulating disc, is present between both the bones, which helps in easy movement of the two bones.

There are four muscles present on each side of the face (masseter, temporalis, lateral pterygoid and medial pterygoid) which are known as the muscles of mastication (chewing) as they help in chewing the food by opening and closing the mouth. The entire TMJ is surrounded by a layer of fibrous tissue which forms a capsule around the joint.  

You can feel the temporomandibular joint by placing both the index fingers in front of each ear opening, basically in front of the tragus (pointed mountain-like structure in the outer surface of the ear) and continuously open and close the mouth. 

The temporomandibular joint disorder (TMD) are the ones which hamper the ability of the jaw to open, close or chew food along with pain and inflammation around the joint. Here in this article, we will talk about all the temporomandibular disorders which can affect the motion of the temporomandibular joint and the treatments to resolve it.

Temporomandibular joint disorder symptoms

The symptoms seen in temporomandibular joint disorder are as follows:

  • Radiating pain or tenderness in the jaws, joint area, neck and shoulders, around the ear
  • Pain increases while chewing, speaking or even while opening the mouth wide for yawning
  • Inability to open mouth wide (reduced mouth opening)
  • Stiffness of the jaw muscle
  • Locking (getting stuck) of jaws while opening or closing the mouth
  • Painless popping or clicking sound from the jaws while closing or opening the mouth.
  • Upper and lower teeth do not fit together properly so it gets difficult to chew food

Temporomandibular joint disorders causes

Temporomandibular disorders can be divided into two categories: disorders due to extrinsic factors and disorders due to intrinsic factors.

1. External causes of temporomandibular disorders 

  • Disorder of the muscles of mastication (chewing food)
    • Muscle splinting: Splinting of muscles to prevent further injury can cause pain and can even lead to further change in the posture of the jaw bone.
    • Myofascial pain dysfunction syndrome (MPD syndrome): Pain that occurs due to fatigues, tension and spasm of the masticatory muscles or the muscles used for chewing food.
    • Myositis: Inflammation of the muscles used for chewing.
  • Trauma: Any trauma to either the temporomandibular joint (TMJ) or the surrounding structures can lead to temporomandibular joint disorder (TMD). 
    • Post-traumatic arthritis: Arthritis followed by an injury to the joint. 
    • Fracture: Fracture of the bones (condyle and temporal bone) that form this joint.
    • Internal disk derangement: Displacement of the articular disk from its original position due to trauma.
    • Myositis: Inflammation of the muscles of mastication after an injury.
    • Myospasm: Spasm of the muscles of mastication after an injury.
    • Tendonitis: Inflammation of the tendons that connect the bones and the muscles
  • Trismus: Trismus is a condition in which the person has restricted mouth opening due to muscle spasm. It happens due to many reasons, such as:

2. Internal causes of temporomandibular disorders 

  • Trauma: Any trauma to the internal structures of TMJ can lead to temporomandibular joint disorder. 
    • Dislocation: Abnormal forward or backward movement of the condylar head (part of the lower jaw that forms the joint) beyond its normal limits can lead to its dislocation. It can lock the jaw while the mouth is open or closed.
    • Hemarthrosis: Bleeding within the joint cavity.
    • Intracapsular fracture: Fracture of the bone which forms the joint (condylar head of the lower jaw) and is present within the capsule (the membrane around the joint).
    • Extracapsular fracture: Fracture of the bone which is not present inside the capsule or membrane. The fractured part of the bone is near the joint.
  • Disk displacement: Any displacement of the disk, present between the two bones of the joints, can cause a temporomandibular joint disorder.
  • Arthritis: There are various medical conditions that can lead to inflammation in the TMJ, which causes a temporomandibular joint disorder. Some of the medical conditions that lead to joint inflammation are: 
  • Developmental defects: Certain defects in the structures that form the joint, which may have been present since birth, can lead to temporomandibular joint disorders.
    • Condylar agenesis or hypoplasia: Missing or underdeveloped condyle (round part of the lower jaw) would make an improper joint, leading to temporomandibular joint disorders. 
    • Bifid condyle: The condyle is supposed to be a round, ball-shaped structure, but in rare cases, it may have a notch in-between, making it a two-headed structure. This makes it difficult to form a joint, thus leading to temporomandibular joint disorders.
  • Ankylosis: Ankylosis is the word used for a stiff joint, which does not have the ability to move, thus the jaw gets locked in a certain position. 
  • Tumours: Various cancerous (fibrosarcoma and chondrosarcoma) and non-cancerous tumours (osteoma and osteochondroma) of the joint bones can lead to temporomandibular joint disorders.

Temporomandibular joint disorder (TMD) diagnosis

Your dentist may take your detailed medical and dental history and would manually examine the problematic areas such as the head, neck, face, and jaw. The following scans are done to find out the reason behind temporomandibular disorder:

  • Orthopantomogram (OPG): It is a panoramic dental X-ray, which helps in examining the entire upper and lower teeth, jaws and TMJ.
  • CT scan: The doctor may prescribe a CT scan to determine which bone in the joint or surrounding area is damaged and to what extent, to cause TMD.
  • MRI scan: Doctors may need an MRI scan to uncover any problems in the articulating disk present between the joint and the soft tissue surrounding the joint.

Temporomandibular joint disorder (TMD) prevention

By making some small changes in your regular life, you can prevent the occurrence of temporomandibular joint disorders:

  • Do not eat extremely hard food, try eating properly cooked soft foods. 
  • Do not try cracking open a walnut or attempt opening the metal caps of bottles with your teeth, as you might end up fracturing your teeth as well as the jaw bone. 
  • If you feel a little bit of pain in your joint, you can apply ice packs on your jaw joint (in front of the opening of the ear).
  • Try and avoid severe jaw movements like opening mouth wide for yawning or singing and continuous chewing of gum.
  • Meditate and relax to reduce stress
  • Your dentist may ask you to do some jaw exercises such as side to side movement of the jaw, restricted movement of the jaw, among others, that would help in easing the jaw movements.
  • If you clench your teeth or grind your teeth a lot, even during sleep, your doctor may give you a mouth guard that would protect your teeth and, by extension, the jaw.

Treatment of temporomandibular joint disorder (TMD)

Drug therapy for a temporomandibular joint disorder

Medicines may be used to provide pain relief in temporomandibular joint disorders (TMD). Drug therapy includes the use of:

  • NSAIDs: Over-the-counter painkillers can help to deal with the pain. However, your dentists may prescribe you non-steroidal anti-inflammatory drugs (NSAIDs) to relieve the pain as well as the inflammation surrounding the joint - so check with your doctor before taking any medicines. NSAIDs include medications like ibuprofen and aspirin. In cases where NSAIDs do not bring the patient relief from the pain, doctors may prescribe stronger analgesics like celecoxib which directly act on the pain stimulators and provide relief.
  • Antidepressants: Tricyclic antidepressants are given to patients with chronic pain, as they prevent the transfer of pain transmitting neurotransmitters (serotonin and norepinephrine) in the brain thus blocking the pain. The dentists may prescribe small doses of amitriptyline to improve sleep pattern, decrease bruxism (teeth grinding) and reduce muscle and joint pain.
  • Muscle relaxants: Muscle relaxants help in reducing the pain and spasm in the muscles of mastication (chewing muscles) that may have caused the TMJ disorder. Medications like diazepam and carisoprodol are given to relax the muscles.

Non-invasive therapy for temporomandibular joint disorder

Non-invasive therapies are the ones which do not involve any surgery but help in the treatment. Non-invasive therapies for TMJ disorders include:

  • Counselling the patient: Your dentist may educate you about the factors and behaviours that may aggravate your pain, so you can avoid them. Habits such as clenching or grinding of teeth, opening the mouth wide for yawning, biting fingernails and continuously chewing of a piece of gum, can lead to temporomandibular joint disorders.
  • Occlusal splints: It is a part of conservative treatment for temporomandibular joint disorders. Autorepositioning splints (allow the teeth to position themselves in their favourable position) and anterior repositioning splints (teeth are placed at a specific position) are the two methods by which splints are placed on the teeth. The splints are devices that prevent the teeth from meeting each other while biting.
  • Physical therapy: The doctor may give exercises and relaxation training to stretch and strengthen the jaw muscles. A physical therapist may use a vapocoolant material like fluoromethane on the muscles of mastication and then stretch them to reduce the level of pain in the jaws. The doctor may also use ultrasound and friction massage to relieve the fatigue of the muscles around the joint.
  • Transcutaneous electrical nerve stimulation (TENS): This is one of the therapies which helps in relieving the pain of the temporomandibular joint disorders using electrical stimulation. 

Invasive therapy for a temporomandibular joint disorder

If the patient does not respond to the drug or non-invasive therapy, the maxillofacial surgeons may have to treat the patients with the help of surgical treatment. The invasive treatment of temporomandibular joint disorders involves:

  • Injections: To relieve the pain, the doctor may inject a corticosteroid to relieve the inflammation, or give a local anaesthetic to numb the area to relieve the pain. The doctor may also inject botox (botulinum toxin type A) in the jaw muscles to relieve the pain associated with temporomandibular joint disorders. 
  • Arthrocentesis: Arthrocentesis is a minimally invasive procedure where fine needles are inserted into the TMJ which act as a port to facilitate the irrigation of the joint. It also helps in breaking up the fine adhesions present near the TMJ.
  • Arthroscopy: Arthroscopy of the TMJ involves the insertion of small tubes (cannula) into the joint space followed by the placement of an arthroscope (a camera-like device) to clearly visualise the structures around the joint. It allows easy access to the problematic site and does not require the opening of the entire joint. TMJ arthroscopy is less risky than open-joint surgery.
  • Disk repositioning surgery: This is an open-joint surgery done during disk dislocation. In this surgery, the extra wedge of bone or tissues is removed and the disk is placed back in its normal position. 
  • Modified condylotomy: Modified condylotomy addresses the TMJ indirectly, with surgery on the mandible, but not in the joint itself. It may be helpful for the treatment of pain and if locking of the jaw is experienced.
  • Total joint replacement: The complete joint is replaced in the case of joint destruction due to trauma or tumour or infection. A custom-made or pre-fabricated prosthesis is used to reconstruct the joint. However, sometimes the doctor may manipulate the already existing bone structure to form a new joint.


References

  1. National Institutes of Health[Internet]. U.S. Department of Health & Human Services; TMJ Disorders.
  2. Prof. Dr. Neelima Anil Malik. [link] 3rd Edition. New Delhi: Jaypee Brothers Medical Publishers (P) LTD. 2012:236-260

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