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The Temporomandibular Joint (TMJ) Patient Information

Introduction

The two jaw joints are known as the temporomandibular joints (TMJs). They are ‘hinge and gliding’ type joints with discs similar to the knee joint. The rounded upper end of the lower jaw is known as the condyle and the socket is the fossa. The disc, which is tough and rubbery acts like a shock absorber and moves with the condyle during normal mouth opening and closing. Clicking on its own is common (20% of ‘normal’ people) and unless it is associated with pain and reduced mouth opening, it does not normally require treatment.

Problems with the TMJ and the nearby soft tissues and muscles can cause a variety of symptoms including earache, headache, jaw stiffness, clicking and grating noises, pain on chewing, and an abnormal bite.  

TMJ disorders

There are a number of causes, however most are due to an injury or a blow on the jaw, overloading of the joint(s) from tooth grinding or clenching and other jaw-related habits.

Internal derangement

The disc lies out of position and may then obstruct the normally smooth sliding movement of the condyle during mouth opening. Sometimes the disc becomes stuck to the fossa. This may be due to altered lubrication in the joint. People may experience clicking in the joint. Sometimes there is no noise. Pain in the joint tends to occur with mouth opening. Internal derangement may be due to a known injury but often occurs due to overload, and wear and tear.

Myofascial pain

‘Myo’ refers to muscles. Aching pain of the facial muscles, more specifically the muscles that move the jaws, may accompany internal derangement or occur on its own. Often it is associated with overuse of the jaw muscles such as with fingernail biting, tooth grinding or clenching. Identifying and correcting the cause is important in the management of myofascial pain. Bite splints and physiotherapy may also be helpful.

Arthritis

Many forms of arthritis may affect the TMJ. Osteoarthritis (degenerative ‘wear and tear’) is most common and is usually associated with a grating noise in the joint due to a tear in the disc. Inflammatory arthritis such as rheumatoid or psoriatic arthritis may also involve the TMJ. Joint pain and swelling is common. Occasionally alterations in the bite are noted. Idiopathic condylar resorption and synovial chondromatosis are rare problems affecting the TMJ, which may present with arthritic symptoms.

Dislocation

Dislocation of the jaw joints may affect one or both sides. The jaw (and mouth) becomes stuck open and, in the case of one-sided dislocation, is pushed to one side. Some people with lax joints have a tendency to dislocate. For others dislocation is usually due to trauma. Initial management involves reducing the dislocation. Patients may present to a Hospital Emergency Department for this. Surgery may be required to prevent recurrent dislocation.

Trauma

A blow to the jaw may result in a ‘sprain’ of the TMJ with effusion (swelling, pain and abnormal bite), a ‘torn ligament’ (tear to the supporting ligaments of the joint) or injury to the disc and its attachments. Fractures of the condyle are common. They may be associated with a dislocation, fracture of the bone of the ear canal and rarely, fracture of the fossa.

Condylar hyperplasia

Overgrowth of the condyle of the lower jaw may result in an abnormal bite and facial asymmetry. A combination of jaw joint and orthognathic (jaw) surgery is required to correct this problem.

Ankylosis

‘Fusion’ of the TMJ is the occasional late outcome of trauma or infection. Surgical correction usually involves replacement with an artificial joint.

Investigation of TMJ problems

Most TMJ disorders can be diagnosed from the history and clinical examination. Further investigations that may be required include: 

  • Plain x-rays 
  • Blood tests 
  • Arthrography 
  • Arthroscopy 
  • CT scan 
  • MRI scan 
  • Bone scan

Overview of treatment of TMJ problems

Disorders of the TMJ and their associated structures are common and do not result in ongoing or chronic problems. The majority of TMJ problems do not require surgery.

Internal derangement and myofascial pain occur most commonly. Management should be kept as simple (and reversible) as possible. Symptoms associated with these disorders tend to come and go, and often resolve spontaneously. Simply resting the joints by avoiding harmful habits such as gum chewing or grinding of the teeth, adopting a soft diet and eating small portions can help. The application of localised heat (by way of a wheat bag or warm flannel) and the use of short-term anti-inflammatory pain-relief medication such as Nurofen can relieve symptoms. A custom made bite-splint, worn at night over the top teeth, will unload the joint and can aid recovery. Physiotherapy may also be recommended. TMJ arthrocentesis (joint wash-out) is a common procedure used to reduce pain and improve mouth opening for patients with internal derangement. If the disc is torn or significant degenerative arthritis is present, open surgery may be required.

Inflammatory forms of TMJ arthritis are often managed jointly, by an Oral and Maxillofacial Surgeon and a Rheumatologist.

Dislocation, trauma, condylar hyperplasia, and ankylosis involving the TMJ usually require more complex surgical management.

Surgery

Arthrocentesis

Indication: internal derangement.

This is a simple procedure carried out under sedation and local anaesthetic, in an operating theatre. It takes about half an hour. A needle is inserted into the upper joint space. A syringe is attached to the needle and used to push fluid into the joint. This stretches the surrounding joint capsule and aims to free up the disc so that it can move more freely. A second needle is then inserted so that the joint can be ‘washed out’. Fluid enters the joint through one needle and out the other. This removes the ‘sticky’, inflamed fluid from the joint. Normally a steroid anti-inflammatory medicine (Betamethasone) is injected into the joint prior to removal of the needles. The jaw is then exercised. Arthrocentesis is successful in reducing joint pain and improving mouth opening in about 70% of patients with TMJ internal derangement.

Arthrotomy

Indication: internal derangement, arthritis, recurrent dislocation.

Arthrotomy is an operation where the joint is opened up. This enables direct visual assessment of the joint spaces, disc and cartilage surfaces of the condyle and fossa. Adhesions (bands of scar tissue which limit free movement of the disc) can be released or menisectomy (removal of the disc) performed if the disc is torn. Eminectomy (reducing the height of the ‘bony stop’ at the front of the fossa) is occasionally undertaken for internal derangement or recurrent TMJ dislocation. Patients undergoing arthrotomy are usually in the operating theatre for 2-3 hours and in hospital for one night afterwards.

Total TMJ replacement

Indication: End-stage arthritis, ankylosis.

Customised computer-generated artificial (titanium, cobalt, nickel and high-molecular-weight polyethylene) TMJs are available. This is an option for patients with TMJ disorders non-responsive to other treatment. This is complex and expensive surgery. The technology to perform this surgery has been available for about 15 years. John Edwards, from our Group, was the first surgeon in New Zealand to place one of these artificial joints. Results to date have been very encouraging.

Final comment

Occasional clicking of the TMJ is so common as to be considered normal. Pain and limited opening is also common and usually responds to simple measures. We will always try to help in the least invasive way possible. It is very important that treatment does not cause further harm. Sometimes less is more!

Please contact us if you have any questions or are unsure about any of the information provided.
 
Phone: +64 9 369 5566,
Fax: +64 9 369 5570
Email: contactus@aoms.co.nz
Address: Ground Floor, Quay Park Health, 68 Beach Road,
Auckland Central
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