Orofacial pain encompasses a range of conditions affecting the jaw, mouth, face, and associated regions. Temporomandibular disorders (TMD) are a subset of these conditions, characterized by symptoms such as face and neck muscle pain, nerve pain, temporomandibular joint (TMJ) pain, hearing problems related to the TMJ, and altered range of motion. TMD is a highly prevalent and painful musculoskeletal condition impacting the masticatory system, affecting an estimated 50-75% of the population at some point in their lives. This condition predominantly affects females, a phenomenon hypothesized to be linked to estrogen, as estrogen receptors have been identified in the TMJ and other joints. Typically, TMD onset occurs after puberty, peaking during the reproductive stage of life.
What Causes TMD?
Determining the exact cause of TMD can be challenging, as it often involves multiple factors. Primary TMD may arise from excessive strain on the jaw joints and the muscles controlling chewing, swallowing, and speech. This strain can result from habitual behaviors such as teeth clenching, grinding, and other parafunctional activities. Additionally, there is a strong relationship between TMD pain and psychosocial disorders, including stress, depression, chronic fatigue, and sleep disturbances. Trauma to the jaw, head, or neck, arthritis, and displacement of the jaw joint discs can also cause TMD pain.
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TMD frequently overlaps with other painful medical conditions, such as chronic headaches (especially migraines), lower back pain, rheumatic diseases, fibromyalgia, chronic pelvic pain, chronic tinnitus, or irritable bowel syndrome, potentially exacerbating TMD symptoms. This overlap suggests that TMD is a functional pain syndrome associated with central sensitization of the pain pathway and functional changes in genetically susceptible individuals.
There is a notable correlation between TMD and autoimmune rheumatic diseases (Table 1), such as rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, and osteoarthritis. These conditions share inflammatory components and autoimmune behaviors, contributing to TMD. A recent study by the National Institute of Dental and Craniofacial Research identified clinical, psychological, sensory, genetic, and nervous system factors that increase the risk of developing chronic TMD.
Table 1. Important clinical features and serologic tests for diagnosis and monitoring rheumatoid arthritis
| Characterized by joint (including TMJ) swelling and tenderness, with the destruction of synovial joints |
| 90% of patients are positive for RF |
| Anti-CCP + in 70% of RA pts (low-level nonspecific) |
| C-RP: persistent CRP indicates poor prognosis; monitor 2-4 times yearly. |
| ESR: influenced by factors unrelated to inflammation such as size, shape, and a number of red blood cells, albumin, globulin, and fibrinogen levels, often measured along with C-RP. |
| CBC: monitor side effects of medications which may decrease RBC, WBC, and/or platelets. |
| BUN, Liver function test, urinalysis: to monitor toxicity of medications that may have adverse effects on the kidneys or liver. |
Anti-CCP: anti-cyclic citrullinated peptide; RF: rheumatoid factor; RA: rheumatoid arthritis; ESR: erythrocyte sedimentation rate; CBC: complete blood count; RBC: red blood cells; WBC: white blood cells; BUN: blood urea nitrogen
Next Steps in Diagnosis and Examination
Patients often seek care for masticatory muscle pain, chronic headaches, and neck pain, particularly when these symptoms are unresolved despite treatment for systemic illnesses. A thorough medical history is crucial, including the patient’s current medications and systemic diseases. The physical examination should assess occlusion (e.g., missing teeth), jaw mobility, masticatory muscles, and the TMJ. Diagnostic imaging may be indicated, such as panoramic radiographs, CT scans, MRI, arthrography, EMG, scintigraphy, and ultrasound. Additionally, exploring biopsychosocial issues that the patient may be experiencing is important.
Treatment Approaches
Treating patients with TMD and comorbid systemic diseases can be complex and requires a multidisciplinary approach. Communication with the patient’s existing healthcare team, including physicians, is essential. Consulting with specialists such as physical therapists, rheumatologists, psychiatrists/psychologists, neurologists, connective tissue specialists, sleep specialists, and endocrinologists may be necessary.
Therapeutic procedures for TMD include thermal therapy, rest and posture exercises for the jaw and neck, jaw stretching exercises, and spray-and-stretch or ice-and-stretch techniques. For pain or muscle spasms, trigger point injections with anesthetics or neurotoxins may be used. TMJ injections can help calm the joint in appropriate cases. An occlusal splint may be indicated to protect the teeth from abnormal forces or retrain patients with parafunctional habits.
Conclusions and Future Directions
A thorough medical history assessment and physical examination improve our understanding of patients with TMD pain. As the classifications of orofacial pain become more precise and diagnoses improve, a better understanding of pain mechanisms will lead to more effective treatment recommendations. Multimodal approaches, integrating biomedical therapies such as pharmacological or surgical interventions with complementary therapies, are necessary to enhance therapeutic outcomes.
Continued research and collaboration across disciplines will be crucial in advancing the diagnosis and treatment of TMD and related orofacial pain conditions, ultimately improving patient care and outcomes.
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References
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- Fiorillo L, Musumeci G. TMJ Dysfunction and Systemic Correlation. J Funct Morphol Kinesiol. 2020 Mar 9;5(1):20. doi: 10.3390/jfmk5010020. PMID: 33467236; PMCID: PMC7739301.
- International Classification of Orofacial Pain, 1st edition (ICOP). Cephalalgia. 2020;40(2):129-221. doi:10.1177/0333102419893823
- Contreras EFR, Fernandes G, Ongaro PCJ, Campi LB, Gonçalves DAG. Systemic diseases and other painful conditions in patients with temporomandibular disorders and migraine. Braz Oral Res. 2018 Jul 23;32:e77. doi: 10.1590/1807-3107BOR-2018.vol32.0077. PMID: 30043839.
- Gruca, O., Tysiąc-Miśta, M., Czelakowska, A., Łanowy, P., Bichalski, M., Dzindzio, J., … & Biel, M. (2019). Relationship of temporomandibular disorders with selected systemic diseases. Prosthodontics, 69(1), 68-83.
