Bruxism

Bruxism is an umbrella term grouping together different motor phenomena of jaw muscles, including teeth grinding, teeth clenching and bracing or thrusting of the mandible.

Can occur during sleep (sleep bruxism) or wakefulness (awake bruxism).

Aetiology is mainly dependent on central factors (stress sensitivity, emotions, personality features, sleep regulation, autonomic nervous system).

Bruxism may result in tooth wear or cracks, dental restoration or implant failure, jaw muscle hypertrophy, pain and/or fatigue in jaw muscles, temporal headache, toothache, temporomandibular disorders, disturbance of bed partner's sleep, and reduction in overall quality of life.

Treatment is symptomatic and depends on the presence of clinically relevant consequences rather than the presence of bruxism itself.

Management options include counselling, different types of oral appliances, cognitive-behavioural approaches, physiotherapy, and, rarely, relaxant drugs for short-term use.

Treatment of any conditions associated with bruxism should also be optimised.

Historically, classifications and definitions of bruxism have varied widely. Classical bruxism activities involve clenching or grinding of the teeth; however, there is an emerging consensus that bruxism may involve masticatory muscle activity without tooth contact, for example, bracing which describes maintaining a certain mandibular position and thrusting which describes forcefully moving the mandible in a forwards or lateral direction.

An international consensus meeting in 2017 defined bruxism as follows:[1]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 Nov;45(11):837-44. https://onlinelibrary.wiley.com/doi/10.1111/joor.12663 http://www.ncbi.nlm.nih.gov/pubmed/29926505?tool=bestpractice.com

• Sleep bruxism (SB): a masticatory muscle activity during sleep that is characterised as rhythmic (phasic) or non-rhythmic (tonic) and is not a movement disorder or a sleep disorder in otherwise healthy individuals.

• Awake bruxism (AB): a masticatory muscle activity during wakefulness that is characterised by repetitive or sustained tooth contact and/or by bracing or thrusting of the mandible and is not a movement disorder in otherwise healthy individuals.

SB and AB are considered as separate conditions. Both definitions emphasise masticatory muscle activity because this may have clinical consequences.[1]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 Nov;45(11):837-44. https://onlinelibrary.wiley.com/doi/10.1111/joor.12663 http://www.ncbi.nlm.nih.gov/pubmed/29926505?tool=bestpractice.com

Bruxism can be considered a risk factor for negative oral health consequences, rather than a disorder per se. The bruxism construct has evolved over the years to consider the phenomenon a motor activity that may be a sign of an underlying condition, represent a normal variation of behaviour in otherwise healthy individuals, or a protective factor associated with one or more positive health outcomes (e.g., restoring airway patency after sleep apnoea events or releasing emotional tension).[2]Manfredini D, Colonna A, Bracci A, et al. Bruxism: a summary of current knowledge on aetiology, assessment and management. Oral Surg. 2019 Oct 23;13(4):358-70.