Bruxism

Bruxism is involuntary and repetitive teeth grinding and/or jaw clenching due to increased masticatory muscle activity either while asleep (sleep bruxism) or awake (awake bruxism). The exact cause of bruxism remains unknown, but it is believed to be multifactorial, with potential factors including genetic predisposition, sleep architecture, psychological stressors and disorders (e.g., sleep disorders, anxiety disorder), neurological changes and disorders (e.g., due to stimulatory drug use, brain trauma, autonomic nervous system dysfunction). Bruxism is considered primary if it cannot be associated with a medical condition or a certain substance and secondary if it can be associated with a psychiatric or neurological condition (e.g., sleep disorders, cerebral palsy) or the use of a particular substance (esp. stimulants, e.g., SSRIs, anxiolytics, dopaminergic drugs, amphetamine, caffeine). Clinical features of bruxism include abraded teeth, tongue indentations, recessed gums, linea alba in the cheek, headaches, locking of the jaw, temporomandibular joint pain, and facial pain. Diagnosis is based upon self-report, third-party observation (e.g., family member), and physical examination. Electromyography of the masticatory muscle and polysomnography (for sleep bruxism) showing increased muscle activity may support the diagnosis.Treatment includes patient education (e.g., stress management, cognitive behavioral training) and, in secondary bruxism, treatment of any underlying condition, cessation of substance use, and/or adjustment of medication regime. An occlusal splint may be used to relax the jaw and protect the teeth while sleeping. If left untreated, bruxism can lead to severe tooth damage, such as dental attrition and abfraction.

• General: involuntary and repetitive teeth grinding and/or jaw clenching due to increased masticatory muscle activity ^[1]
• Sleep bruxism: bruxism that occurs while asleep (mainly during NREM sleep stage 2)
• Awake bruxism: bruxism that occurs during wakefulness
• Primary bruxism: no association with any medical condition
• Secondary bruxism: associated with medical conditions (e.g., parasomnias), medication (e.g., antidepressants), and substance use (e.g., alcohol, caffeine)

• Sleep bruxism
  • Reported prevalence is 5–8%. ^[2]
  • Reported prevalence in children is approx. 35%. ^[3]
• Awake bruxism: Reported prevalence in the general population is 22–31%. ^[4]

Epidemiological data refers to the US, unless otherwise specified.

The exact causes and pathophysiology of bruxism are unknown, but the following associations have been identified.

• Primary bruxism
  • Psychological (e.g., stress, anxiety)
  • Positive family history
• Secondary bruxism
  • Sleep disorders (e.g., parasomnias)
  • Neurological disorders (e.g., cerebral palsy, Huntington disease)
  • Medication (e.g., methylphenidate, dextroamphetamine, antidepressants, antipsychotics)
  • Recreational drugs; (e.g., amphetamines, cocaine, alcohol, tobacco, caffeine)

• Teeth grinding and/or jaw clenching (often noticed by a sleeping partner or family member in sleep bruxism)
• Tenderness of the jaw muscle
• Oral lesions
  • Cheek and/or lip biting: canker sores, bite line (linea alba) on the cheeks
  • Tongue biting: tooth indentations on the tongue, scalloped tongue
• Temporomandibular joint pain
• Limited jaw opening
• Masticatory muscle hypertrophy

• Non-instrumental approach ^[5]
  • Self-report (questionnaire and/or medical history)
  • Third-party observation (e.g., sleeping partner)
  • Physical examination
• Instrumental approach ^[5]
  • Electromyography of the masticatory muscle showing increased muscle activity
  • Polysomnography showing increased muscle activity (for sleep bruxism)

• All types
  • Patient education and behavior modification
    • Stress management
    • Cognitive-behavioral therapy
    • Treatment of underlying conditions (e.g., anxiety disorder, substance use disorder)
    • Sleep hygiene
    • Biofeedback training
  • Avoidance of substances associated with bruxism (see “Etiology” above)
  • Medication (rarely used): clonidine, L-dopa, clonazepam
• Sleep bruxism: occlusal splint (mouthguard) to relax the jaw and protect the teeth while sleeping

• Temporomandibular joint disorder (TMD) ^[7][8][9]
• Tooth damage: dental attrition, dental abfraction, tooth fractures

We list the most important complications. The selection is not exhaustive.