Bruxism is unconscious repetitive movement or bracing of the jaw muscles, characterized by grinding of teeth and clenching of the jaw, typically while sleeping but also while awake. This is often a transient occurrence in children, rarely continuing into adolescence. In adults, it can cause damage to teeth and contribute to muscular headaches. Symptoms include jaw pain, sleep disturbance, tooth pain, dystonia, and headache. Damage to tooth enamel and dental restorations may be observed on examination.

Bruxism may occur in association with other sleep disorders such as snoring and obstructive sleep apnea, with trismus, or with temporomandibular joint disorders. Clinical diagnosis is based on a history of tooth grinding during sleep confirmed by the patient's bed partner, or parents in the case of pediatric patients. Polysomnography is not required for diagnosis but should be performed when etiology is uncertain or when a comorbid sleep disorder, such as obstructive sleep apnea (OSA), is suspected.

Treatment involves repair of dental damage and prevention of damage with occlusal guards and splints.