The temporomandibular joint

Fig. 9.1 OPT showing idiopathic condylar resorption.

Trismus

   Classically, an inability to open mouth due to muscular spasm, but commonly used to refer to limited mouth opening.

   Normal inter-incisal mouth opening is 35–45mm.

   Extra-articular causes:

    •   odontogenic infection;

    •   facial trauma including dento-alveolar surgery;

    •   myofascial pain/TMJDS;

    •   following ID LA block;

    •   depressed fractured zygoma/arch;

    •   radiation fibrosis;

    •   tetanus;

    •   quinsy;

    •   local malignancy;

    •   submucous fibrosis;

    •   coronoid hyperplasia;

    •   malignant hyperpyrexia.

   Intra-articular causes:

    •   ankylosis—bony/fibrous;

    •   facial trauma—effusion, fracture;

    •   meniscus displacement;

    •   osteophyte formation;

    •   septic arthritis.

Myofascial pain

   Synonyms: myofacial pain/facial arthromyalgia.

   Spectrum of facial pain disorders secondary to parafunctional habits, without signs and symptoms of TMJ internal derangement.

Temporomandibular joint dysfunction

   Most common non-infective pain disorder of the oro-facial region.

   Meta-analysis show that the overall prevalence of TMJDS in population studies ranges from 30–45%.

   More common in image; image:image ratio of 1:3.

   Mean age is between 30 and 40 years.

   Pain is typically diffuse, cyclical and distributed in multiple sites, especially the muscles of mastication; it is frequently worse in the morning.

   Related to stress and parafunctional habits.

   Associations: depression, back pain, tension headaches, migraine, irritable bowel syndrome, fibromyalgia.

Features

   Pain.

   Clicking.

   Locking.

   Crepitus.

   Trismus.

Clinical findings

   Tenderness of the pre-auricular region and muscles of mastication.

   Clicking, usually with abnormal path of opening.

   Evidence of parafunctional activity—such as clenching causing dental attrition, linea alba affecting the buccal mucosa, scalloped tongue, masseteric hypertrophy, and biting of finger nails.

Internal derangement

   Occurs where the articular disc within the joint interferes with smooth functioning of the joint.

   Clicking usually indicates reducible displacement of the disc.

   Clicking is usually related to abnormal paths of opening, with protrusion and/or lateral deviation.

   Some patients will go on to develop locking.

   Closed lock: mouth cannot open beyond around 25mm as the head of the condyle impinges on an anteriorly displaced disc.

   Open lock: patient unable to close the mouth without manipulation, since condyle is trapped in front of posteriorly displaced disc.

   Locks may be reducible (patient can manipulate the jaw to regain mobility) or irreducible.

   Disc may perforate (associated with joint crepitus and the development of osteoarthritis).

Investigations

   Routine radiography does not change management in classical TMJDS.

   An OPT may eliminate dental pathology radiating to the ear in a non-classical pain pattern.

   Radiographic features of OA:

    •   narrowing of joint space;

    •   bone cyst (geode) formation;

    •   remodelling;

    •   osteophyte formation.

   MRI is the gold standard imaging for the TMJs. It can be useful in the assessment of patients with trismus where a closed lock (or other pathology) is suspected (Fig. 9.2).

   Approximately a third of asymptomatic patients have anterior displacement of their discs on MRI scan.

   CT scanning is superior for assessing bone detail.

image

Fig. 9.2 MRI of the right temporomandibular joint.

Management/treatment

   Reassurance and explanation.

   Education regarding parafunctional habits.

   Jaw exercises, e.g. straight line to eliminate click.

   Physiotherapy.

   Analgesia.

   Heat.

   Rest/soft diet/relaxation.

   Splints/bite guards/bite raising appliances:

    •   variety of materials, designs, and for either jaw;

    •   possible mechanisms of action include reduction of bruxism and other parafunctional habits, production of a gap between the condyle and fossa to free the disc, and possible placebo effect.

Other interventions

Tricyclic antidepressants

   Have analgesic and muscle relaxant effects independent of their antidepressant action.

   No RCTs show efficacy in TMJDS.

Occlusal rehabilitation

   Most patients with abnormal occlusions do not suffer TMJ pain.

   No evidence of benefit.

   Orthodontic treatment or orthognathic surgery is not a treatment for TMJDS.

Arthrocentesis and manipulation

Only gold members can continue reading. Log In or Register to continue

Mar 2, 2015 | Posted by in Oral and Maxillofacial Surgery | Comments Off on The temporomandibular joint
Premium Wordpress Themes by UFO Themes