Sleep Bruxism: An Integrated Clinical View

Genetics and sleep bruxism: a systematic review and meta-analysis of studies with twins

OBJECTIVE

To systematically review the literature regarding the concordance of sleep bruxism (SB) between monozygotic (MZ) and dizygotic (DZ) twins.

METHODS

The registration for this systematic review was accomplished in the International Prospective Register of Systematic Reviews (PROSPERO, No. CRD42021251751). As of July 2022, four databases were searched, including PubMed, Scopus, Embase, and Web of Science, as well as the grey literature in Google Scholar and OpenGrey. Observational studies evaluating SB in MZ and DZ twins of any age and sex were included. For the evaluation of the risk of bias, the Joanna Briggs checklist was utilized. The certainty of evidence was assessed via the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Pooled and subgroup meta-analyses were performed to estimate concordance of SB ​​between twins (p < 0.05).

RESULTS

In total, 3,155 records were identified. In the qualitative analysis, eleven studies were included; of these, seven were included in the meta-analysis. The majority of the articles exhibited a low risk of bias (63.6%). Greater SB concordance was observed between MZ twins than between DZ twins in the analysis of general concordance (OR = 1.47; 95% CI = 1.07-2.02) and also positive concordance (OR = 1.53; 95% CI = 1.29-1.81). Within the subgroup analyses, the significance of the findings remained only for the reported/self-reported SB regarding general concordance (OR = 1.44; 95% CI = 1.07-1.95) and positive concordance (OR = 1.55; 95% CI = 1.28-1.88). Low certainty of the evidence was observed for the general concordance analysis, while moderate certainty was observed for the positive concordance.

CONCLUSION

There was a higher concordance of SB in MZ twins compared to DZ twins, indicating a possible genetic influence on the condition's occurrence.

Risk of sleep problems in a clinical sample of children who stutter

PURPOSE

Previous studies have shown increased prevalence of sleep problems among people who stutter. However, there is a lack of knowledge about what these sleep problems may specifically be.

METHOD

Fifty children who stutter (CWS) from 6;0 to 12;9 years of age and 50 age- and gender-matched controls participated in this study. Parents did not report coexisting conditions, excepting stuttering and/or sleep problems. Sleep problems were investigated using a standardized questionnaire answered by parents. The questionnaire shows cut-off scores to identify the risk of sleep problems as a whole and on each one of the six subscales (i.e., disorders of initiating and maintaining sleep; sleep breathing disorders; disorders of arousal; sleep-wake transition disorders; disorders of excessive somnolence; and sleep hyperhidrosis). Scores above the cut-off are suggestive of sleep problems.

RESULTS

Twenty-one CWS scored higher than the cut-off on the sleep questionnaire compared to only two controls (p < 0.00001). Specifically, CWS scored higher than controls in disorders of initiating and maintaining sleep, sleep-wake transition disorders (especially jerking, sleep talking, and bruxism), and disorders of excessive somnolence (p < 0.0083, corrected for multiple comparisons).

DISCUSSION

Compared to controls, CWS are at greater risk for sleep problems, which are not consequences of coexisting disorders. Present findings confirm and expand current knowledge about sleep problems in CWS. Directionality possibilities and clinical implications are discussed.

Secondary bruxism: A valid diagnosis or just a coincidental finding of additional masticatory muscle activity? A narrative review of literature

INTRODUCTION

Bruxism is defined as a repetitive masticatory muscle activity that can manifest it upon awakening (awake bruxism-AB) or during sleep (sleep bruxism-SB). Some forms of both, AB and SB can be associated to many other coexistent factors, considered of risk for the initiation and maintenance of the bruxism. Although controversial, the term 'secondary bruxism' has frequently been used to label these cases. The absence of an adequate definition of bruxism, the non-distinction between the circadian manifestations and the report of many different measurement techniques, however, are important factors to be considered when judging the literature findings. The use (and abuse) of drugs, caffeine, nicotine, alcohol and psychoactive substances, the presence of respiratory disorders during sleep, gastroesophageal reflux disorders and movement, neurological and psychiatric disorders are among these factors. The scarcity of controlled studies and the complexity and interactions among all aforementioned factors, unfortunately, does not allow to establish any causality or temporal association with SB and AB. The supposition that variables are related depends on different parameters, not clearly demonstrated in the available studies.

OBJECTIVES

This narrative review aims at providing oral health care professionals with an update on the co-risk factors and disorders possibly associated with bruxism. In addition, the authors discuss the appropriateness of the term 'secondary bruxism' as a valid diagnostic category based on the available evidence.

CONCLUSION

The absence of an adequate definition of bruxism, the non-distinction between the circadian manifestations and the report of many different measurement techniques found in many studies preclude any solid and convincing conclusion on the existence of the 'secondary' bruxism.