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.

Bruxism can occur during sleep (sleep bruxism [SB]) or wakefulness (awake bruxism [AB]).

Etiology is mainly dependent on central factors (stress sensitivity, emotions, personality features, sleep regulation, autonomic nervous system), rather than on peripheral nervous system function or dental morphology and occlusion.

In healthy individuals, bruxism can be considered a muscle behavior, which can be harmless or represent a risk factor for clinical consequences, rather than being a disorder per se. Treatment need depends on the presence of clinically relevant consequences rather than the presence of bruxism itself.

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

Treatment is symptomatic. Management options include different types of oral appliances (OA), cognitive-behavioural approaches, psychotherapy, physiotherapy, and, rarely, relaxant drugs for short-term use.

Treatment of any conditions associated with bruxism should also be optimized. Bruxism may be self limiting, particularly in children. Therefore, observation only strategies may be appropriate.

Historically, classifications and definitions of bruxism have varied widely. 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://www.doi.org/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 characterized as rhythmic (phasic) or nonrhythmic (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 characterized 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 emphasize masticatory muscle activity because this may have clinical consequences.[2]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://www.doi.org/10.1111/joor.12663 http://www.ncbi.nlm.nih.gov/pubmed/29926505?tool=bestpractice.com

Classical bruxism activities are clenching and grinding of the teeth. However, there is an emerging consensus that bruxism may involve masticatory muscle activity without tooth contact. For example, bracing describes forcefully maintaining a certain mandibular position and thrusting describes forcefully moving the mandible in a forward or lateral direction.