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Temporomandibular Disorders

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Introduction

The term temporomandibular disorders (TMD) refers to pain and/or dysfunction of the temporomandibular joint, the muscles, or surrounding structures, while TMJ refers specifically to the temporomandibular joint.[1][2]

Between five and 12% of people worldwide experience TMD symptoms that require treatment at any given time, with women approximately twice as likely as men to experience symptomatic TMD and seek treatment.[3] However, a much larger proportion of the population exhibits signs or symptoms of TMD at some point in their lives.[3] It is reported that more than one-third of the population will experience at least one sign or symptom of TMD, such as joint sounds (clicking or crepitus), pain upon palpation of the masticatory muscles, or restricted jaw movement.[2] This distinction between symptomatic prevalence (those actively seeking or needing treatment) and the presence of any sign or symptom is crucial for understanding the scope of this condition.

TMD Classification Systems

Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)

The gold standard for diagnosing TMD is the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). This classification system is comprehensive but time-intensive, making it more suited to research settings than daily clinical practice. Nevertheless, understanding this framework helps clinicians appreciate the complexity of TMD.[4]

The DC/TMD classifies TMD into two primary categories: pain-related and intra-articular.

Pain-related disorders include myalgia and arthralgia. Myalgia subdivides into local myalgia, myofascial pain, and myofascial pain with referral. Arthralgia refers to joint pain localised directly to the temporomandibular joint (TMJ). The DC/TMD also recognises headache attributed to TMD. This is specifically defined as a headache in the temple region, aggravated by jaw function, and provoked on palpation.[4]

Intra-articular disorders are biomechanical or structural issues within the joint. These include disc displacement with reduction (where the disc relocates correctly during opening), disc displacement with reduction with intermittent locking (where the jaw occasionally locks but generally reduces), disc displacement without reduction with limited opening (where the disc remains malpositioned and restricts mouth opening) and disc displacement without reduction without limited opening (where the disc does not relocate on opening and remains anterior to the condyle).[4] The DC/TMD also includes degenerative joint disease and subluxation.[4]

Table 1 summarises the DC/TMD classification system:

Tab.1 Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)
Pain-related Intra-articular
Myalgia Disc displacements
Arthralgia Osteoarthritis
Headache Subluxation

Clinical Classification for Temporomandibular Disorders

For clinical purposes, a simpler classification is often more practical: myogenous (muscular), arthrogenous (joint), or mixed.

Myogenous presentations include myalgia (with the same subclassifications as the DC/TMD), tendinopathy of the temporalis tendon at the coronoid process insertion, muscle spasm and myositis.

Arthrogenous presentations include joint pain, osteoarthritis, hypermobility disorders, hypomobility disorders and disc displacements.[2]

This page uses the clinical classification system when discussing causes of TMD.

Myogenous (Muscular) Disorders

Myogenous disorders originate from the masticatory muscles and associated soft tissues. They are classified into four primary subcategories: myalgia, muscle spasm, temporalis tendinopathy, and myositis.

Myalgia

There are three types of myalgia: local myalgia, myofascial pain, and myofascial pain with referral.[5]

Local myalgia is defined as pain confined to the site of palpation of the muscles of mastication (such as the temporalis or masseter), without spreading to other structures.[5]

Myofascial pain is defined as pain that spreads within the muscle's boundary on palpation.

Myofascial pain with referral is defined as pain that extends beyond the muscle's immediate boundary to other structures, such as the teeth, TMJ, ear, head, or neck.

Muscle Spasm

Muscle spasm can cause significant jaw pain and movement limitations (trismus), commonly affecting the masseter, temporalis, and pterygoid muscles. Causes include prolonged mouth opening during dental procedures, stress, bruxism and postural dysfunction. In patients with head and neck cancer, radiation-induced inflammation or fibrosis and scar tissue can also cause trismus.[6]

Temporalis Tendinopathy

Temporalis tendinopathy is caused by overuse of the temporalis muscle, typically from repetitive jaw movements and teeth clenching.[7] Tenderness and swelling may be present at its insertion on the coronoid process, palpable just below the zygomatic arch with the jaw slightly open.

Myositis

Masticatory myositis causes localised pain in the masticatory muscles. This pain is often exacerbated by movement, such as chewing, talking, or yawning. Additional symptoms include trismus, tenderness, fatigue, and localised swelling over the affected muscles.[8]

Arthrogenous Disorders

Arthrogenous TMDs include inflammatory conditions and structural changes within the joint, known as internal derangement.

Inflammatory conditions

Inflammatory conditions, such as rheumatoid arthritis, ankylosing spondylitis, infectious arthritis, Reiter's syndrome and gout, can affect the TMJ.[9]

In synovitis, the synovium and joint capsule become inflamed. There is often pain at rest, with limited range of motion, particularly at end range.[8]

Retrodiscitis can be caused by trauma, progressive disc displacement, or dislocation. The retrodiscal tissue can become inflamed and cause severe pain. The jaw may deviate away from the painful side at rest.[10]

Degenerative arthritis can occur in the TMJ, often producing crepitus that can be felt or heard with a stethoscope. It is more common in women, increases with age, and is potentially linked to trauma, joint overload, inflammatory or autoimmune conditions, and disc displacement.[11]

Clinicians working with children should be alert to systemic inflammatory conditions. Generalised pain, palpable inflammation, and jaw hypermobility warrant referral to paediatric rheumatology.[2]

Internal derangement

Internal derangement refers to structural changes within the joint. This can be caused by direct trauma (e.g., a blow to the jaw or falling on the chin), indirect trauma (e.g., whiplash), or repetitive strain from persistent clenching, grinding, hard chewing or prolonged periods of mouth opening during dental procedures.

The articular disc normally sits between the mandibular condyle and fossa. In disc displacement, the disc is most commonly displaced anteriorly.

Disc displacement with reduction: the displaced disc relocates to its normal position during jaw opening, typically producing an audible or palpable click. Early clicks indicate less advanced displacement; later clicks suggest more severe displacement. The jaw often deviates towards the affected side before the click.[10][12]

Disc displacement without reduction: the disc does not reduce, resulting in pain and loss of range of motion (locked jaw). The jaw will often deviate towards the affected side.[13]

Hypermobility

Temporomandibular joint hypermobility involves greater-than-normal range of motion and is classified into two main categories: subluxation and luxation.[14]

Subluxation: a milder form where patients can self-reduce the mandibular condyles back into the glenoid fossae by relaxing the masticatory muscles, self-manipulation or side-to-side movements. Symptomatic hypermobility is a milder subdivision of subluxation, associated with joint clicking and jerky jaw movements during wide opening or closing.[14]

Luxation: patients are unable to self-reduce and require assistance from another person (relative or clinician).[14]

Causes of TMD

TMD has many potential causes, including trauma, bruxism, cervical spine dysfunction, respiratory/airway complications, forward head posture, systemic diseases, hormonal influences, dental malocclusion, and psychosocial variables.[2][15]

Accurate diagnosis is essential to identify modifiable contributors and exclude serious underlying pathology.[16] Treatment addresses modifiable factors such as posture, breathing, and muscle tension, while managing non-modifiable contributors.

"Factors like acute trauma, osteoarthritis we manage but can't change, while posture, breathing, muscle tension we can address." -- Micaela Weinberg[2]

Anxiety and Depression

Anxiety and depression have a bidirectional relationship with TMD: people with anxiety and depression have an increased risk of TMD, while those with TMD experience higher rates of anxiety and depression.[17][18] A 2024 study found that of 250 people diagnosed with TMD, over half had depression and/or anxiety.[19]

Anxiety and depression can influence TMD presentation and outcomes in the following ways:[2]

  • poorer treatment outcomes
  • increased pain perception
  • decreased treatment compliance
  • elevated muscle activity in mastication and pericranial muscles
  • increased parafunctional habits (including grinding)
  • sympathetic nervous system-mediated microarousal during sleep
  • central sensitisation with lowered pain thresholds[20][21]

This optional video discusses the biopsychosocial aspects of TMD:

[22]

Bruxism

Bruxism is an abnormal clenching or grinding of the teeth. It can occur during waking and/or sleeping hours and can lead to chronic tension in the muscles of mastication.[23]

Cervical Spine and TMJ Function

"The cervical spine and TMJ are one system. You cannot separate them." -- Micaela Weinberg[2]

The cervical spine and the TMJ are functionally and neurologically interconnected. Mouth opening involves upper cervical extension, while mouth closing involves upper cervical flexion. Neurophysiologically, C1-C3 nerve afferents overlap with the trigeminal nerve, meaning that cervical spine irritation can present as TMJ pain.[24]

Breathing/Posture and TMJ Function

Forward head posture and mouth breathing can contribute to TMD by altering condyle position, overworking accessory muscles, and activating the sympathetic nervous system.[25] [26]

Systemic Factors

Systemic factors such as hypermobility, inflammatory conditions, connective tissue disorders, and hormonal fluctuations play a role in the development of TMD.

Resources

References

  1. ↑ National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Health Care Services; Board on Health Sciences Policy; Committee on Temporomandibular Disorders (TMDs): From Research Discoveries to Clinical Treatment; Yost O, Liverman CT, English R, et al., editors. Temporomandibular Disorders: Priorities for Research and Care. Washington (DC): National Academies Press (US); 2020 Mar 12. 2, Definitions and Scope: What Are TMDs? Available from https://www.ncbi.nlm.nih.gov/books/NBK557995/ [last accessed 3.1.2026]
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Weinberg M. Temporomandibular Disorders Course. Physiopedia Plus, 2026.
  3. ↑ 3.0 3.1 Alqutaibi AY, Alhammadi MS, Hamadallah HH, Altarjami AA, Malosh OT, Aloufi AM, Alkahtani LM, Alharbi FS, Halboub E, Almashraqi AA. Global prevalence of temporomandibular disorders: a systematic review and meta-analysis. Journal of Oral & Facial Pain and Headache. 2025 Jun 12;39(2):48.
  4. ↑ 4.0 4.1 4.2 4.3 Schiffman E, Ohrbach R, Truelove E, Look J, Anderson G, Goulet JP, et al. Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications: recommendations of the International RDC/TMD Consortium Network* and Orofacial Pain Special Interest Group†. J Oral Facial Pain Headache. 2014 Winter;28(1):6-27.
  5. ↑ 5.0 5.1 Winocur-Arias O, Friedman-Rubin P, Abu Ras K, Lockerman L, Emodi-Perlman A, Greenbaum T, Reiter S. Local myalgia compared to myofascial pain with referral according to the DC/TMD: Axis I and II results. BMC Oral Health. 2022 Feb 4;22(1):27.
  6. ↑ Charters E, Walker E, Clayton N, Dunn M, Turner J, Clark JR. Evidence for stretch duration applicable for the treatment of trismus: a scoping review. Journal of Clinical Practice in Speech-Language Pathology. 2025 Jan 2;27(1):3-21.
  7. ↑ Kim SB, Bae H, Lee KW, Hu KS, Abe S, Kim HJ. Anatomical consideration of ultrasonography‐guided intraoral injection for temporal tendinitis. Clinical Anatomy. 2024 Sep;37(6):628-34.
  8. ↑ 8.0 8.1 Zhang X, Gao W, Zhou J, Dai H, Xiang X, Xu J. Low-intensity pulsed ultrasound in the treatment of masticatory myositis and temporomandibular joint synovitis: A clinical trial. Journal of stomatology, oral and maxillofacial surgery. 2024 Feb 1;125(1):101632.
  9. ↑ Balasubramanium, R; Delcanho, R, Temporomandibular disorders and related headache; Headache, Orofacial Pain and Bruxism, Diagnosis and multidisciplinary approaches to management, Chapt 7, pg 76-77, Churchill Livingston Elsevier, 2009.
  10. ↑ 10.0 10.1 ATSÜ S. Management of Temporomandibular Disorders. International Studies and Evaluations in the Field of Dentistry. 2024 Oct:29.
  11. ↑ Ravelo V, Vargas E, Garcia Guevara H, Sacco R, Navarro P, Olate S. TMJ replacement in degenerative disease: a systematic review. Journal of Clinical Medicine. 2025 Jan 17;14(2):580.
  12. ↑ Poluha RL, Canales GD, Costa YM, Grossmann E, Bonjardim LR, Conti PC. Temporomandibular joint disc displacement with reduction: a review of mechanisms and clinical presentation. Journal of Applied Oral Science. 2019 Feb 21;27:e20180433.
  13. ↑ Al-Baghdadi M, Durham J, Araujo-Soares V, Robalino S, Errington L, Steele J. TMJ disc displacement without reduction management: a systematic review. Journal of Dental Research. 2014 Jul;93(7_suppl):37S-51S.
  14. ↑ 14.0 14.1 14.2 Tuijt M, Parsa A, Koutris M, Berkhout E, Koolstra JH, Lobbezoo F. Human jaw joint hypermobility: Diagnosis and biomechanical modelling. Journal of Oral Rehabilitation. 2018 Oct;45(10):783-9.
  15. ↑ Li DTS, Leung YY. Temporomandibular Disorders: Current Concepts and Controversies in Diagnosis and Management. Diagnostics (Basel). 2021 Mar 6;11(3):459.
  16. ↑ Chisnoiu AM, Picos AM, Popa S, Chisnoiu PD, Lascu L, Picos A, Chisnoiu R. Factors involved in the aetiology of temporomandibular disorders - a literature review. Clujul Med. 2015;88(4):473-8.
  17. ↑ Felin GC, da Cunha Tagliari CV, Agostini BA, Collares K. Prevalence of psychological disorders in patients with temporomandibular disorders: A systematic review and meta-analysis. The Journal of Prosthetic Dentistry. 2024 Aug 1;132(2):392-401.
  18. ↑ Yap AU, Zheng Y, Liu T, Li Y, Wo PK, Du S, Xiong X. Impact of comorbid depression and anxiety on temporomandibular disorders related pain, sleep, function, behaviours, and quality of life. Scientific Reports. 2025 Oct 13;15(1):35620.
  19. ↑ Qazafi D. Anxiety and depression prevalence in temporomandibular joint disorder patients. Journal of Population. 2025:206-12.
  20. ↑ Wan J, Lin J, Zha T, Ciruela F, Jiang S, Wu Z, Fang X, Chen Q, Chen X. Temporomandibular disorders and mental health: shared etiologies and treatment approaches. The Journal of Headache and Pain. 2025 Mar 12;26(1):52.
  21. ↑ Salinas Fredricson A, Krüger Weiner C, Adami J, Rosén A, Lund B, Hedenberg-Magnusson B, Fredriksson L, Naimi-Akbar A. The role of mental health and behavioural disorders in the development of temporomandibular disorder: a SWEREG-TMD nationwide case-control study. Journal of Pain Research. 2022 Dec 31:2641-55.
  22. ↑ Interview with Kevin D. Huff, DDS - About the Biopsychosocial Model of Care Available from: https://www.youtube.com/watch?3xYiGalgRtg [last accessed 7/1/2026]
  23. ↑ Steen JP, Jaiswal KS, Kumbhare D. Myofascial Pain Syndrome: An Update on Clinical Characteristics, Etiopathogenesis, Diagnosis, and Treatment. Muscle & Nerve. 2025 May;71(5):889-910.
  24. ↑ Romero-Reyes M, Akerman S, Rapoport AM. Optimising combined treatment for migraine and temporomandibular disorders (TMDs). Cephalalgia. 2025 Sep;45(9):03331024251368882.
  25. ↑ Ohmure H, Miyawaki S, Nagata J, Ikeda K, Yamasaki K, Al‐Kalaly A. Influence of forward head posture on condylar position. Journal of Oral Rehabilitation. 2008 Nov;35(11):795-800.
  26. ↑ Gu L, Gai K, Liu X, Wang J, Xu L, Zhu Y. Association Between Mouth Breathing and the Temporomandibular System: A Narrative Review. Journal of Oral Rehabilitation. 2025 Jul;52(7):1152-9.
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