What is Bruxism?
Bruxism is a repetitive jaw-muscle activity characterized by clenching or grinding of teeth and/or bracing or thrusting of the mandible, occurring either during sleep (sleep bruxism) or wakefulness (awake bruxism). 1
Clinical Definition and Classification
Bruxism manifests in two distinct circadian patterns 1:
- Sleep bruxism (SB): Occurs during sleep, affecting approximately 13% of adults, and is regulated centrally rather than by peripheral morphological factors 2
- Awake bruxism (AB): Occurs during waking hours and is more commonly associated with hyperkinetic movement disorders and anxiety 3
The etiology remains multifactorial and incompletely understood, with current evidence suggesting central regulation through pathophysiological and psychosocial factors rather than peripheral morphological causes 2.
Clinical Recognition and Examination Findings
On intraoral examination, bruxism presents with excessive wear facets on teeth, which serve as a key diagnostic indicator. 4
Additional examination findings include 4:
- Muscle hypertrophy of the masticatory muscles
- Tenderness and trigger points in the muscles of mastication and head/neck muscles
- Temporomandibular joint abnormalities including crepitus, clicking, or locking
- Tooth mobility and potential fractures in severe cases
Associated Clinical Consequences
Bruxism leads to multiple complications affecting the stomatognathic system 2, 5:
- Dental damage: Tooth wear, fractures, cracks, and restoration/implant failure
- Periodontal effects: Gingival recession and increased tooth mobility
- Temporomandibular disorders (TMD): Though available evidence does not support bruxism as a direct cause of pain 6
- Headaches: Particularly in association with muscle tension and TMD 4
- Muscle-joint sensitivity: Daily discomfort and muscular pain 5
Important Clinical Context
When evaluating patients with suspected bruxism, assess for associated factors including clenching habits, jaw joint clicking or locking, impact on sleep, mood disturbances, and other chronic pain conditions. 4
Bruxism frequently coexists with 4, 5:
- Temporomandibular disorders (TMD has genetic predisposition)
- Gastroesophageal reflux disease (GERD), which can compound dental wear
- Psychological factors: Depression, anxiety, stress, and chronic widespread pain
- Movement disorders: Particularly those involving basal ganglia dysfunction 3
The condition requires multidisciplinary evaluation when severe, as the association between bruxism, dietary habits (particularly acidic foods), and digestive disorders can lead to accelerated dental destruction 5.