Updating the Bruxism Definitions: Report of an International Consensus Meeting (Verhoeff, Lobbezoo et al, 2025)
Introduction
Bruxism has been receiving increasing attention from clinicians and researchers.
An international group of bruxism experts produced a series of consensus papers, resulting in the publication of the Standardised Tool for the Assessment of Bruxism (STAB) and the BruxScreen, along with a 12-step guideline for their translation and cultural adaptation.
In 2013, an international consensus definition of bruxism was published, along with a proposal for a grading system.
In 2018, the unspecified bruxism definition was formulated separately for sleep bruxism and awake bruxism, clarifying issues unaddressed in the 2013 paper, and the grading system was modified.
Aspects of the proposed definitions have raised questions and caused confusion among clinicians, researchers, educators, and patients.
A closed workshop was held on March 11, 2024, at the International Association for Dental, Oral and Craniofacial Research (IADR) in New Orleans with bruxism experts.
Discussions during the 2024 workshop led to the three aims of this report: (1) provide a glossary of the existing definitions, (2) discuss frequently asked questions regarding the definitions, and (3) suggest a road map for the next steps to be taken towards a better understanding of bruxism.
Aim 1: Bruxism Glossary
Addresses confusion after the 2018 publication of the definition of unspecified bruxism: ‘Bruxism is a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Bruxism has two distinct circadian manifestations: it can occur during sleep (indicated as sleep bruxism) or during wakefulness (indicated as awake bruxism)’.
Specific, more detailed definitions of sleep bruxism: ‘Sleep bruxism is a masticatory muscle activity during sleep that is characterized as rhythmic (phasic) or non-rhythmic (tonic) and is not a movement disorder or a sleep disorder in otherwise healthy individuals’.
Awake bruxism: ‘Awake bruxism is 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’.
Table 2 serves as a glossary to explain the constituent terms of the three proposed bruxism definitions.
Aim 2: Frequently Asked Questions and Important Points of Discussion Among Experts
Issues that gave rise to confusion were collected, collated, and phrased as questions.
Q&A 1: What Is the Meaning of the Addendum ‘in Otherwise Healthy Individuals’?
The World Health Organization defines health as ‘a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity’.
When assessing bruxism in individuals who are healthy at that specific time point, they are referred to as ‘otherwise healthy individuals’.
To avoid misunderstandings, the addendum ‘in otherwise healthy individuals’ has been removed from the currently proposed specific definitions of sleep and awake bruxism.
Sleep bruxism is 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.
Awake bruxism is 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.
Q&A 2: Is Bruxism a Behaviour or a Disorder?
Bruxism is considered a motor behaviour that may be associated with certain disorders in one of three hypothetical ways:
(1) bruxism of which it is as yet unknown whether or not it is actually associated with a certain disorder or that both are only present at the same time (i.e., primary bruxism),
(2) bruxism that is proven to be associated with a certain disorder, treatment or lifestyle (i.e., secondary bruxism)
(3) bruxism that is part of the signs of a certain disorder, that is, the disorder causes jaw-muscle activities to occur.
Q&A 3: Is Bruxism a Comorbidity or a Risk Factor?
Bruxism is not a disorder and, therefore, cannot be considered a comorbidity.
Bruxism can be associated with other health conditions:
(1) a risk factor when bruxism is associated with one or more negative health outcomes,
(2) a protective factor when bruxism is associated with one or more positive health outcomes
(3) a neutral factor when bruxism is neither a risk factor nor a protective factor.
Bruxism may also act as a protective factor; the most often suggested example is in people with obstructive sleep apnea, where the activity may contribute to maintaining the patency of the upper airway, thus preventing collapse.
Q&A 4: Are We Diagnosing or Assessing Bruxism?
Since bruxism is not a disorder, it is not diagnosed as such.
The motor behaviour is assessed to determine if any positive or negative consequences are associated with it.
Q&A 5: When Do We Manage or Treat Bruxism?
When indicated and possible, negative consequences of bruxism can be managed as long as this does not compromise any potential positive effects of the motor behaviour.
If bruxism is a sign of a disorder, treatment of the underlying disorder may be indicated for medical reasons.
Q&A 6: Is Bruxism a Stable Jaw-Muscle Activity?
Bruxism is known for its fluctuations over time.
Self-reported sleep bruxism seems to be a fairly persistent trait over a 20-year period in same-sex twins.
Self-reported awake bruxism, recorded with a smartphone application, was also found to be quite constant over a 6-month monitoring period.
Device-based sleep bruxism fluctuates considerably over time, whereas self-reported bruxism (sleep, awake) seems to be a fairly persistent trait over longer periods of time.
Q&A 7: Is There any Evidence for Bracing and Thrusting of the Jaw?
Bruxism is commonly associated with clenching and grinding of the teeth, but the definition of bruxism also includes two other characteristics: bracing and thrusting.
Some studies indicate that bracing and thrusting are frequent behaviours and can lead to increased muscle fatigue and pain.
Q&A 8: How to Proceed With Citing the Definition Papers?
Citing the current report is recommended because it covers all definitions and provides comprehensive and updated explanations of all constituent terms.
The addendum ‘in otherwise healthy individuals’ has been removed from the specific definitions of sleep and awake bruxism.
Q&A 9: What Is the Value of the Grading System?
The previously proposed grading system (viz., possible, probable and definite bruxism) has helped to further develop the understanding of bruxism.
The hierarchy is not accurate because self-reporting, clinical examination and device-based tools could conceivably assess different aspects of bruxism.
The recommendation is to call the used assessment tools as they are: subject-based (self-report), clinically based (clinical examination) and device-based (e.g., electromyography, polysomnography) tools.
Q&A 10: When Should We Select One or the Other Assessment Mode?
Self-reporting reflects the patient's experiences and beliefs, and it allows the assessment of the perceived time course of bruxism.
Clinical examination does not measure bruxism itself but rather clinical signs of the motor behaviour.
Device-based tools are used to actually measure jaw-muscle activities, as to provide insight into, for example, the pathophysiological mechanisms or physiological correlates of those activities.
The selection of one or the other assessment mode depends on the actual clinical need or specific research question.
Aim 3: Taking the Next Steps
Implementation strategies need to be developed to promote the integration of the currently proposed bruxism definitions into education, clinical settings and research projects.
There is a paucity of studies on the similarities and differences between sleep/awake bruxism and other orofacial motor activities.
Work will be done on a classification of orofacial motor activities during an upcoming consensus meeting.
Stronger methods, such as Delphi studies, are considered for the next steps.
Further, more research is needed on the associations between sleep bruxism and sleep-related conditions such as obstructive sleep apnea, restless leg syndrome, periodic limb movement during sleep, sleep-related gastroesophageal reflux disease, REM behaviour disorder (RBD), Parkinson's disease and sleep-related epilepsy.
In the future, it will be examined whether these etiological aspects can be added to the definition in a sustainable way.
Conclusion
The report of the 2024 international consensus meeting provides a glossary of all constituent terms of the definitions of unspecified, sleep and awake bruxism that have been published previously.
Responses are provided to frequently asked questions regarding bruxism and its definitions.
The report looks ahead towards the possible next steps to be taken, for example, bruxism in unhealthy individuals who have conditions in which bruxism behaviour is directly increased due to the underlying health condition.
The recommendation is to use the current publication when referring to the definitions of bruxism in clinical and research settings.