Description

• Bruxism is defined as habitual nonfunctional forceful contact of teeth, which is involuntary. These movements can include excessive grinding, clenching, or rubbing of teeth.
• Other nonfunctional (or “parafunctional”) oral habits include movements not involved with normal chewing, swallowing, or speaking, such as chewing pencils, nails, cheek, or lip.
• Sleep bruxism should be distinguished from daytime awake bruxism. Sleep bruxism has been classified as a sleep-related movement disorder.
• Awake bruxism is rare with little or no audible sound during clenching, compared to the loud grinding sound commonly occurring in sleep bruxism.

Epidemiology

• Age/onset
  • In children, prevalence in the literature is highly variable with a range of 4–40%. Prevalence decreases with increasing age.
  • May occur throughout life but frequently tends to peak in early childhood, then decreases with age
  • Sleep bruxism progressively diminishes around 9 to 10 years of age.
  • Infants have been known to grind their teeth during the eruption of primary teeth.
  • May be temporarily or intermittently present, which makes diagnosis difficult
• Gender
  • Recent systematic review of literature reported no gender differences in prevalence.
  • Previous studies suggested girls may be more affected than boys.
• Some studies support higher incidence in children with developmental disabilities, Down syndrome, sleep disorders, and autism.

Risk Factors

Etiology

• The exact cause is not known. It is likely to be a multifactorial process including oral motor activities, regulation of sleep–wake cycle, autonomic, catecholaminergic, hereditary, and psychosocial influences.
• Awake bruxism is more commonly associated with psychosocial factors and psychopathologic symptoms.
• Dental factors (current evidence suggests that they play a small role, only ~10% of cases)
  • Occlusal interferences, including malocclusions, in which teeth do not interdigitate smoothly
  • High dental restorations (e.g., fillings or crowns)
  • Intraoral irritation (e.g., sharp tooth cusp)
  • Teething
• Psychological factors
  • Nervous tension (related to stress, anger, and aggression)
  • Personality disorders
  • Posttraumatic stress disorder
• Common systemic factors
  • Moving between levels of sleep
  • Sleep-disordered breathing
  • Snoring and obstructive sleep apnea
  • Tonsil/adenoid hypertrophy
  • Mouth breathing
  • Neurodevelopmental disorders (e.g., cerebral palsy)
  • Brain injury
  • ADHD
• Other possible factors
  • Asthma
  • Allergies
  • Nasal obstruction
  • Exposure to secondhand smoke
  • Medications (amphetamines, barbiturates, antidepressants—particularly serotonin reuptake inhibitors)