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JariAhlberg

Bruxism

Essentials

  • Bruxism can occur during sleep or when awake.
  • Bruxism can cause symptoms such as dental wear, facial pain, lower jaw movement disorders and symptoms resembling tension neck.
  • Harmful bruxism can be treated by counselling, occlusal appliances, physiotherapy or exercises, and botulinum toxin can be used as medication.

Definition

  • Bruxism is masticatory muscle activity that can be either rhythmic (grinding) or tonic (clenching) or consist of masticatory muscles tensing and/or moving the lower jaw without the teeth being in contact.
  • Bruxism is an independent disorder. Therefore, movement-related symptoms associated with Parkinson's disease, for example, are not consistent with the definition of bruxism even if they do represent involuntary masticatory muscle activity.

Prevalence

  • Less than 10% of adults have bruxism during sleep and about 20% while they are awake.
    • During sleep, short-term bruxism occurs during lighter sleep phases when approaching waking up.
    • Grinding the teeth rarely occurs with the person awake.
    • Clenching the teeth can occur not only during sleep but also for lengthy periods while awake, increasing the total workload of masticatory muscles.

Aetiology

  • Genetic factors play a role in bruxism.
  • Bruxism is regulated by the central nervous system (CNS) and is not influenced by peripheral factors, such as dental occlusion.
  • Many other permanent or transient factors may increase bruxism.
    • Psychological factors
    • Sleep disorders
    • Legal or illegal psychoactive agents
    • Alcohol
    • Smoking
    • Drugs, particularly SSRIs and SNRIs

Physiological effects

  • Muscle activity associated with bruxism may be harmless, harmful or even represent a protective physiological mechanism.
    • Bruxism in association with sleep apnoea may be a protective phenomenon; the movement of the lower jaw has been found to open the airway in such patients.
  • Tooth grinding and the acid effect of gastro-oesophageal reflux disease cause tooth erosion and weaken the dental enamel.
  • Gastro-oesophageal reflux and sleep apnoea increase periods of arousal from sleep, thus also increasing episodes of bruxism.
  • Consequences of harmful bruxism
    • Dental wear
    • Facial pain
    • Movement disorders of the lower jaw
    • Symptoms resembling tension headache

History and status

  • Questions
    • Do you believe that you clench your teeth when asleep or awake?
    • Have you noticed, or has a person you sleep with told you, that you grind your teeth in your sleep?
  • Examinations
    • Tooth wear (grinding)
    • Line on the buccal mucosa (clenching)
    • Tooth impressions on the side of the tongue (clenching)
    • Palpation of masticatory muscles (m. masseter, m. temporalis); is there tenderness or pain?
    • Auscultation of the temporomandibular joints with a stethoscope during lower jaw movements (opening/closing, lateral movements, protrusion)
      • If there is crepitation or pain, further investigations are needed.
    • Ranges and form of movement of the lower jaw should be examined. Both clinical assessment and the patient's view or feeling are important.
      • If the problem is associated with temporomandibular joint disc displacement (anterior dislocation being most common), when opening the mouth, the lower jaw will veer towards the affected joint (no reduction of the disc) or perform an s-shaped movement where, about midway through the movement, the joint clicks as the disc is reduced, and the lower jaw returns to the midline.
      • As the mouth (lower jaw) is closed, a quieter clicking sound will be heard as the disc is anteriorly displaced. A click may also be heard on lateral movement.
    • The patient can be asked to bite on a gauze swab, for instance, on one side; if there is tenderness/pain in the opposite temporomandibular joint, inflammation can be suspected.

Treatment

  • Counselling of the patient
  • Treatment with an occlusal appliance (if tooth grinding during sleep is suspected, otherwise only after due consideration)
  • Physiotherapy (with a physiotherapist familiar with bite problems) or guided exercises performed by the patient
  • Botulinum toxin
    • Botulinum toxin injected into masticatory muscles helps in the treatment of symptoms of muscular origin as a part of the overall treatment.
    • The treatment will not reduce CNS impulses to the masticatory muscles (frequency) but will reduce their contraction force (amplitude) and the work of the masticatory system.
  • Depending on the situation and as necessary, the patient should be referred to a dentist or a specialist in occlusal physiology or pain management for further investigation and treatment.

    References

    • Lobbezoo F, Ahlberg J, Raphael KG, et al. International consensus on the assessment of bruxism: Report of a work in progress. J Oral Rehabil 2018;45(11):837-844 [PubMed]
    • Lobbezoo F, Ahlberg J, Verhoeff MC, et al. The bruxism screener (BruxScreen): Development, pilot testing and face validity. J Oral Rehabil 2023;(): [PubMed]
    • [Pain and functional disorders of the masticatory system (TMD)]. A Current Care Guideline. Working group appointed by the Finnish Medical Society Duodecim and the Finnish Dental Society Apollonia. Helsinki: the Finnish Medical Society Duodecim, 2021 (accessed 8.6.2023). Available in Finnish at http://www.kaypahoito.fi/hoi50057.
    • Riley P, Glenny AM, Worthington HV, et al. Oral splints for patients with temporomandibular disorders or bruxism: a systematic review and economic evaluation. Health Technol Assess 2020;24(7):1-224 [PubMed]
    • Bussadori SK, Motta LJ, Horliana ACRT, et al. The Current Trend in Management of Bruxism and Chronic Pain: An Overview of Systematic Reviews. J Pain Res 2020;13():2413-2421 [PubMed]