Is bruxism a disorder or a behaviour? Rethinking the international consensus on defining and grading of bruxism

Abstract

Summary Inspired by the international consensus on defining and grading of bruxism (Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ et al. J Oral Rehabil. 2013;40:2), this commentary examines its contribution and underlying assumptions for defining sleep bruxism (SB). The consensus’ parsimonious redefinition of bruxism as a behaviour is an advance, but we explore an implied question: might SB be more than behaviour? Behaviours do not inherently require clinical treatment, making the consensus-proposed ‘diagnostic grading system’ inappropriate. However, diagnostic grading might be useful, if SB were considered a disorder. Therefore, to fully appreciate the contribution of the consensus statement, we first consider standards and evidence for determining whether SB is a disorder characterised by harmful dysfunction or a risk factor increasing probability of a disorder. Second, the strengths and weaknesses of the consensus statement’s proposed ‘diagnostic grading system’ are examined. The strongest evidence-to-date does not support SB as disorder as implied by ‘diagnosis’. Behaviour alone is not diagnosed; disorders are. Considered even as a grading system of behaviour, the proposed system is weakened by poor sensitivity of self-report for direct polysomnographic (PSG)-classified SB and poor associations between clinical judgments of SB and portable PSG; reliance on dichotomised reports; and failure to consider SB behaviour on a continuum, measurable and definable through valid behavioural observation. To date, evidence for validity of self-report or clinician report in placing SB behaviour on a continuum is lacking, raising concerns about their potential utility in any bruxism behavioural grading system, and handicapping future study of whether SB may be a useful risk factor for, or itself a disorder requiring treatment.

International consensus on the assessment of bruxism: Report of a work in progress

“…Amongst the series of exchanges over whether bruxism should be considered a disorder, 4–6 Raphael et al 4 pointed out that if higher levels of masticatory muscle activity increase the risk of negative oral health consequences (eg, severe masticatory muscle pain or temporomandibular joint pain, extreme mechanical tooth wear, prosthodontic complications), 12–14 bruxism should be considered a risk factor rather than a disorder in otherwise healthy individuals. Whilst a risk factor is an attribute that increases the probability of a disorder but does not “guarantee” it, a disorder is a condition that is a harmful dysfunction per se, that is inherently causing harm to the person and representing a dysfunction in normal biopsychosocial processes.…”

“…Unlike the rapid acceptance of the new definition for bruxism, the grading system ignited a series of exchanges focused on the practical utility of the system, on the status of bruxism as disorder, behaviour, or risk factor and on the consequences thereof in terms of diagnosis and management. 4–6 …”

Bruxism is a continuously distributed behaviour, but disorder decisions are dichotomous (Response to letter by Manfredini, De Laat, Winocur, & Ahlberg (2016))

“…The authors state that they agree ‘on almost all the arguments’ raised in our recent commentary (3) written as a critique of the original consensus paper. We appreciate their support and agreement, but also welcome the opportunity to respond to several points that they raise, as these points indicate areas in which we need to provide further clarification.…”

Bruxism as a neurological problem (literature review)

“…С учетом близости брук-сизма и оромандибулярной дистонии, а также других форм фокальных дистоний, которые признаны гене-тически обусловленными, наследственность при брук-сизме нуждается в более тщательном изучении. Мы разделяем точку зрения, согласно которой, возможно, бруксизм является отдельным заболеванием [12], но это требует дальнейшего изучения.…”