Bruxism

Bruxism is a repetitive jaw muscle activity characterised by clenching or grinding of the teeth and by bracing or thrusting of the mandible. It occurs during sleep (sleep bruxism, centrally mediated and linked to micro arousals) or wakefulness (awake bruxism, usually clenching). Prevalence is 8 to 31 percent of adults for sleep bruxism, 22 to 31 percent for awake bruxism, and 14 to 17 percent in children.

Sleep bruxism is initiated by sleep arousals with increased sympathetic activity, and associated with sleep disordered breathing, snoring, gastro oesophageal reflux, anxiety and stress, alcohol, caffeine, smoking, and drugs (selective serotonin reuptake inhibitors, venlafaxine, amphetamines, methylphenidate, antipsychotics). It is a risk factor rather than a disease in otherwise healthy people.

Complications include tooth wear, tooth fracture, loss of restorations, hypersensitivity, masticatory muscle pain, headache, temporomandibular disorder, and implant failure.

• Tooth grinding noises heard by a partner or family; morning jaw stiffness or fatigue; temporal headache.
• Tooth wear (flattened incisal and occlusal surfaces with wear facets), cracked teeth, fractured fillings, tooth hypersensitivity, mobility.
• Hypertrophy of masseter muscles, tenderness of masticatory muscles, linea alba (white line on the buccal mucosa), scalloped tongue, buccal ridging, torus.
• Jaw pain, joint clicking, limited opening, earache.
• Associated: snoring, obstructive sleep apnoea, daytime sleepiness, anxiety.
• Red flags: severe tooth wear in a young person (erosion from reflux or eating disorder), neurological disease, medication induced bruxism, and sleep apnoea.

• Clinical diagnosis: report of tooth grinding or clenching plus clinical signs (tooth wear, masseter hypertrophy, muscle tenderness); self-report is "possible bruxism", clinical examination with report is "probable bruxism", and polysomnography with audio and video is "definite" sleep bruxism.
• Examination: wear facets, cracks, restorations, muscle palpation, joint assessment.
• Polysomnography with masseter electromyography and audio video recording (rhythmic masticatory muscle activity, 4 or more episodes per hour) in uncertain or severe cases or with suspected sleep apnoea.
• Questionnaire assessment for stress, anxiety, depression, and sleep quality (Epworth sleepiness scale).
• Review drugs and substances (caffeine, alcohol, tobacco, stimulants).
• Exclude temporomandibular disorder with dental origin, erosive tooth wear, attrition from diet, dystonia, tardive dyskinesia, epilepsy, and sleep apnoea.

• Counselling and behavioural measures: stress management, awareness of daytime clenching ("lips together, teeth apart"), sleep hygiene, reduce caffeine and alcohol, stop smoking, avoid gum chewing, relaxation techniques, biofeedback, and cognitive behavioural therapy.
• Occlusal splint (hard acrylic stabilisation splint covering all teeth in the upper arch), worn at night; protects teeth and does not cure bruxism; review every 6 months.
• Treat the cause: sleep apnoea (mandibular advancement device or continuous positive airway pressure), reflux (omeprazole 20 mg orally once daily for 8 weeks), anxiety or depression, medication change where the drug is the cause (for example, buspirone 5 mg orally twice daily may be added for SSRI-induced bruxism).
• Botulinum toxin type A injected into the masseter (25 to 50 units per side, in 3 to 5 sites) and, if needed, temporalis (10 to 20 units per side) every 3 to 6 months for severe bruxism with muscle pain or hypertrophy or splint failure; adverse effects include chewing weakness, asymmetry, and the loss of masseter bulk.
• Drugs: short term clonazepam 0.5 mg orally at night for 2 to 4 weeks for severe sleep bruxism with muscle pain (avoid long term because of dependence); amitriptyline 10 mg at night for pain.
• Muscle pain: warm compresses 15 minutes twice daily, jaw stretching exercises, ibuprofen 400 mg every 8 hours with food for up to 1 week, physiotherapy.
• Dental management: restore worn teeth after controlling bruxism, with durable materials (zirconia or lithium disilicate), and manage sensitivity with fluoride varnish.
• Children: usually self-limiting; reassure, treat airway obstruction (adenotonsillectomy) and anxiety; splints only for significant wear.
• Follow up: review at 3 months, then every 6 months for splint and tooth wear assessment.
• Counselling: bruxism is rarely harmful when managed; discuss implant and restoration risk.