Temporomandibular joint syndrome

According to the American Association of Orofacial Pain (AAOP) definition, a temporomandibular disorder (TMD) is:
“a collective term embracing a number of clinical problems that involve the masticatory musculature, the Temporomandibular joint and associated structures, or both.” (1)

Several terms have been used in the past to describe TMD which include Costen’s syndrome, temporomandibular joint dysfunction syndrome, temporomandibular joint disorders, and craniomandibular syndrome (1).

Around 60-70% of the general population has at least one sign of a temporomandibular disorder (2)

• only 5% of patients with symptoms will seek treatment
• most common in early adulthood (2) and in women than in men.
• discomfort from these conditions is occasional and temporary
• often they occur in cycles
• the pain finally disappears with little or no treatment
• some develop significant, long-term symptoms (3).

TMD are a class of degenerative musculoskeletal conditions associated with morphological and functional deformities

• TMD include abnormalities of the intra-articular discal position and/or structure as well as dysfunction of the associated musculature

The conditions fall into three main categories (4):

• myofascial pain
  • this is the most common temporomandibular disorder
  • it involves discomfort or pain in the muscles that control jaw function.
• internal derangement of the joint
  • this involves a displaced disc, dislocated jaw, or injury to the condyle.
• arthritis
  • this refers to a group of degenerative/inflammatory joint disorders affects the joint.

Symptoms and signs include painful joint sounds, restricted or deviating range of motion, and cranial and/or muscular pain known as orofacial pain (5)

TMD is a symptom complex (i.e. a group of symptoms occurring together and characterizing a particular disease)

• aetiological factors for TMJ disorders include:
  
  
  • likely to be multifactorial
    
    
  • capsule inflammation or damage and muscle pain or spasm may be caused by:
    • parafunctional habits (e.g., bruxism [teeth grinding], teeth clenching, lip biting)
    • stress, anxiety
    • abnormalities of the intra-articular disk
    • parafunctional habits may play a role in initiating or perpetuating symptoms in some patients
      • the cause-and-effect relationship remains uncertain
    • some evidence to suggest that anxiety, stress, and other emotional disturbances may exacerbate TMJ disorders, especially in patients who experience chronic pain
      • interest in occlusal factors as a causative factor in TMD was especially widespread in the past, and the theory has since fallen out of favour and become controversial due to lack of evidence - a systematic review concluded that " seems to lack ground to further hypothesise a role for dental occlusion in the pathophysiology of TMD.." (6)

Short term treatment consists of a very soft diet and simple analgesia, and may be sufficient for mild symptoms:

• non-pharmacological treatments include patient education and reassurance, jaw rest, a soft diet, warm compress over the region of pain and passive stretching exercises (7)
  • stretching and jaw exercises may improve range of movement but may not necessarily improve pain
• pharmacological treatments (7)
  • unless contraindicated, nonsteroidal inflammatory drugs (NSAIDs) represent the first-line pharmacological agents used for acute and chronic pain associated with TMD
  • muscle relaxants, such as benzodiazepines
    • may be useful in patients with recurrent masticatory muscle spasm and chronic bruxism where relaxation techniques are ineffective
  • tricyclic antidepressants, such as amitriptyline
    • can be trialled as they are often effective in other chronic and regional pain disorders

Long term treatment may involve dental correction or stress relaxation. Referral to a specialist clinic may be needed:

• an evidence review states that moderate certainty evidence shows that, compared with placebo or sham procedures, cognitive behavioural therapy augmented with biofeedback or relaxation therapy, therapist-assisted jaw mobilisation, and manual trigger point therapy are probably among the most effective interventions for pain relief (8)

Notes:

• temporomandibular articulation is composed of bilateral, diarthrodial, temporomandibular joints (TMJs)
  • each joint is formed by a mandibular condyle and its corresponding temporal cavity (glenoid fossa and articular eminence)
    • TMJ and its associated structures play an essential role in
      • guiding mandibular motion
      • distributing stresses produced by everyday tasks, such as chewing, swallowing, and speaking

Reference:

• (1) Durham J. Temporomandibular disorders (TMD): an overview. Oral Surgery 2008;1:60–68
• (2) Dimitroulis G. Temporomandibular disorders: a clinical update. BMJ. 1998;317(7152):190-4
• (3) TMJ disorders. National Institute of Dental and Craniofacial Research. National Institutes of Health.
• (4) Temporomandibular joint syndrome (TMJ).University of Iowa Hospitals and Clinics.2008
• (5) Murphy MK et al. Temporomandibular Joint Disorders: A Review of Etiology, Clinical Management, and Tissue Engineering Strategies.Int J Oral Maxillofac Implants. 2013 Nov-Dec; 28(6): e393-e414.
• (6) Manfredini D et al. Temporomandibular disorders and dental occlusion. A systematic review of association studies: end of an era?J Oral Rehabil. 2017 Nov;44(11):908-923
• (7) Lomas J, Gurgenci T, Jackson C, Campbell D. Temporomandibular dysfunction. Aust J Gen Pract. 2018 Apr;47(4):212-215.
• (8) Yao L, Sadeghirad B, Li M, Li J, Wang Q, Crandon H N et al. Management of chronic pain secondary to temporomandibular disorders: a systematic review and network meta-analysis of randomised trials BMJ 2023; 383 :e076226 doi:10.1136/bmj-2023-076226