Sleep bruxism is a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. In sleep medicine, it has been described as a sleep-related movement disorder characterized by simple repetitive movements and transient arousals during sleep. In dentistry, according to the current international consensus, sleep bruxism has been described as a behavior. As for consequences, sleep bruxism may provoke tooth wear, fracture of restorations, temporomandibular disorder, headache, and muscular orofacial pain. Dental therapy involves palliative procedures such as protective plates and care for the temporomandibular joint, in addition to multidisciplinary care for associated factors. There is controversy among researchers about the association between emotional factors and bruxism. However, systematic reviews have proven that emotions act as a trigger for bruxism. A sequential change from autonomic and brain cortical activities precedes sleep bruxism, suggesting that the central and/or autonomic nervous systems, rather than peripheral sensory factors, have a dominant role in sleep bruxism onset. Therefore, the association between malocclusions and poorly adapted dental restorations was ruled out as being a peripheral factor. Comorbidities include snoring, hypertension, headaches, temporomandibular disorder, encephalopathy, epilepsy, affective disorders, psychological stress, personality traits, and anxiety. At this time, the diagnosis of definitive bruxism is made with polysomnography or with electromyography, associated with clinical signs of the stomatognathic system and the patient's self-report. Neuroimaging studies provide evidence of functional changes in oral motor cortical areas in patients with bruxism. Treatment of sleep bruxism includes dental plates, behavioral modification, and medication.
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• Sleep bruxism is primarily associated with rhythmic masticatory muscle activity (RMMA).
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• Bruxism is often reported or observed by sleep partners; self-reporting has a substantial false-negative rate. The clinical signs of the stomatognathic system associated with polysomnography or EMG are important.
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• Snoring, sleeptalking, and nightmares are factors associated with sleep bruxism.
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• Sleep bruxism is centrally rather than peripherally mediated.
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• Treatment is palliative and involves intraoral appliances, behavioral therapies, and medications.
Historical note and terminology
The allusion to grinding and clenching of teeth comes from ancient times, mentioned in the Bible in gospels such as Luke 13:28, Matthew 13:41-2, Matthew 8:12, Matthew 13:50, Matthew 22:13, and Matthew 24:51. In 1938, Miller introduced the term “bruxism” for bruxomania or repetitive teeth grinding (57). One of the first recorded notations of this phenomenon was from Black, who commented that "abrasion of the teeth may tend to remove the cusps of the teeth quite rapidly” (10). Later descriptions noted the potential effects of this disorder. In 1941, Bodecker described a patient whose bruxism had destroyed the clinical crowns of all the lower anterior teeth (11).
Sleep bruxism and awake bruxism were not differentiated for several decades; however, the sleep-wake state dependence appears to demonstrate that these are distinct disorders that have different underlying causes and require different treatments (45).
An international expert consensus examined several definitions of bruxism from sleep medicine and dental organizations and recommended that bruxism be defined as a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible (44). In the most recent publication of the international consensus, experts defined bruxism as a behavior (45).