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INTRODUCTION

Classification

Temporomandibular disorders (TMDs) (M26-60 to M26-63, according to the International Classification of Diseases) are the second most common musculoskeletal conditions (after chronic low back pain) resulting in pain and disability. Thus TMDs are differentially diagnosed among other orofacial pains (OFPs) using 1 of 4 current classification systems for OFP (Table 26–1).

Table 26–1Classification systems for orofacial pain.

When not otherwise specified, this chapter refers to the AAOP classification system.

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Schiffman  E,  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.  [PubMed: 24482784]
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Renton  T, Durham  J, Aggarwal  VR. The classification and differential diagnosis of orofacial pain. Expert Rev Neurother. 2012 May;12(5):569–576.  [PubMed: 22550985]

General Considerations

TMDs are a set of musculoskeletal disorders affecting the temporomandibular joint (TMJ), the masticatory muscles, or both. TMDs comprise many diverse diagnoses with similar signs and symptoms affecting the masticatory system, which can be acute, recurrent, or chronic. TMDs are rarely life-threatening, but can impact heavily on an individual’s quality of life. Studies show that about 3% to 7% of the population need treatment.

TMDs occur disproportionately in women of childbearing age in a ratio of 4:1 to 6:1, and the role of estrogens seems to show an association. The prevalence drops off dramatically for both men and women after age 55.

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Prasad  S, Kumar  N, Shruthi  H, Kalavathi  S. Temporomandibular pain. J Oral Maxillofac Pathol. 2016 May-Aug;20(2):272–275.  [PubMed: 27601822]

Etiology

The cause of TMDs is variable and uncertain, and it is thought to be multifactorial in most cases. Genetic factors have recently been implicated. Most factors are not proven causal factors, but they are associated with TMDs. Predisposing factors increase the risk of TMDs. Predisposing factors are trauma, both direct (eg, blows to the jaw) and indirect (eg, whiplash injuries), and stress. Microtrauma is caused by clenching and grinding of the teeth. Stress can be a predisposing factor owing to the disruption of restorative sleep and the increase of nocturnal bruxism. Trauma and stress are also precipitating factors.

Perpetuating factors that sustain a TMD are stress, poor coping skills, harmful habits such as clenching and grinding, and poor posture. Nonrestorative sleep also may be a major factor in the perpetuation of chronic jaw pain.

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Sangani  D, Suzuki  A, VonVille  H, Hixson ...

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