Sleep bruxism: The past, the present, and the future-evolution of a concept

BACKGROUND

The concept of sleep bruxism (SB) has evolved exponentially over the past several decades. Many theories and hypotheses have been proposed as to the definition, pathophysiology, and management of SB, from the early 1960s through the present. The role of peripheral factors, such as dental occlusion, in the pathogenesis of SB has been discarded.

TYPES OF STUDIES REVIEWED

The authors searched several electronic databases (ie, PubMed, Google Scholar, Web of Science, Embase, and Ovid MEDLINE) for studies on bruxism. The search was conducted from January 1961 through May 2023 and yielded 4,612 articles, of which 312 were selected for comprehensive review after eliminating duplicates and nonfocused articles.

RESULTS

There has been an evident progressive shift from the role of peripheral factors, such as dental occlusion, to more central factors, such as the involvement of a central pattern generator as well as the autonomic nervous system, in the genesis of bruxing movements. There is continued robust interest in the dental community to elucidate the contributing factors involved in SB.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The neurophysiology of SB appears to be leaning more toward central rather than peripheral factors. There is increasing evidence of the role of the autonomic nervous system, genetics, and comorbidities in the genesis of SB. The scientific literature seems to refute the role of dental occlusion in the causation of bruxing movements. As per the literature, there has been a paradigm shift in the definition and genesis of SB and its possible dental implications and management, which also highlights the need for succinct scientific studies in this regard.

Sleep bruxism and associated physiological events in children with obstructive sleep apnea: a polysomnographic study

STUDY OBJECTIVES

The aim of this study was to evaluate the physiological events associated with sleep bruxism (Sleep Bruxism [SB]; presence of mandibular movement activity) and the control window (4 minutes prior to SB event, where no mandibular movement activity was detected) in a polysomnography study in children with mild sleep apnea.

METHODS

Polysomnography data from children aged 4 to 9 years old diagnosed with mild sleep apnea were analyzed by 2 trained examiners. The mandibular movement activity (bruxism event; SB) was classified into phasic and tonic. The control window was selected 4 minutes prior to the SB event. All physiological events were recorded in both bruxism and control windows, including sleep phase (N1, N2, N3, and rapid eye movement), arousal, leg movements, tachycardia, bradycardia, oxygen desaturation, and number of obstructive and central sleep apnea events. The moment in which those phenomena occurred when associated with SB was also analyzed (before/after). Data were analyzed using 95% confidence intervals (α = 5%).

RESULTS

A total of 661 mandibular movements were analyzed and classified as tonic (n = 372) or phasic (n = 289). The mean apnea-hypopnea index was 1.99 (SD = 1.27) events/h. The frequency of leg movements, microarousal, and tachycardia was increased in SB events when compared with the control window (P < .05). There was an increase in bradycardia frequency in the control window when compared with SB (in both tonic and phasic events). The frequency of obstructive and central apnea during SB was lower when compared with the other physiological phenomena.

CONCLUSIONS

There is a difference in the physiological parameters evaluated in children with mild sleep apnea when comparing the 2 windows (SB and control). Sleep bruxism is associated with other physiological phenomena, such as leg movements, tachycardia, and microarousal. The use of a control window (where no mandibular activity was detected) was representative since it did not show activation of the sympathetic nervous system.

CITATION

Bonacina CF, Soster LMSFA, Bueno C, et al. Sleep bruxism and associated physiological events in children with obstructive sleep apnea: a polysomnographic study. J Clin Sleep Med. 2024;20(4):565-573.

Instrumental assessment of sleep bruxism: A systematic review and meta-analysis

This systematic review and meta-analysis (MA) aimed to evaluate the diagnostic validity of portable electromyography (EMG) diagnostic devices compared to the reference standard method polysomnography (PSG) in assessing sleep bruxism. This systematic review was completed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement and was registered with PROSPERO prior to the accomplishment of the main search. Ten clinical studies on humans, assessing the diagnostic accuracy of portable instrumental approaches with respect to PSG, were included in the review. Methodological shortcomings were identified by QUADAS-2 quality assessment. The certainty of the evidence analysis was established by different levels of evidence according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. A meta-analysis of diagnostic test accuracy was performed with multiple thresholds per study applying a two-stage random effects model, using the thresholds offered by the studies and based on the number of EMG bruxism events per hour presented by the participants. Five studies were included. The MA indicated that portable EMG diagnostic devices showed a very good diagnostic capacity, although a high variability is evident in the studies with some outliers. Very low quality of evidence due to high risk of bias and high heterogeneity among included studies suggests that portable devices have shown high sensitivity and specificity when diagnosing sleep bruxism (SB) compared to polysomnography. The tests performed in the MA found an estimated optimal cut-off point of 7 events/hour of SB with acceptably high sensitivity and specificity for the EMG portable devices.

Evaluation of signs and symptoms of temporomandibular disorders and incisal relationships among 7-10-year-old Turkish children with sleep bruxism: A cross-sectional study

OBJECTIVE

To study the signs and symptoms of temporomandibular disorders (TMDs) and incisal relationships related to sleep bruxism and parafunctional habits among children.

METHODS

The study consisted of 106 children (53 with and 53 without bruxism) between the ages of 7 and 10. A general questionnaire and Diagnostic Criteria for Temporomandibular Disorders Axis I examination form were used for each child.

RESULTS

There were significant differences between children according to pain, headache, midline deviation, opening pattern, temporomandibular joint noise, overjet, overbite, corrected deviation, and pain disorders (p < 0.05). According to the logistic regression, the higher scores of "mouth breathing" and "horizontal incisal overjet" were independent risk factors for TMDs. The lack of "bruxism" and "sleeping with open mouth" were protective factors for TMDs.

CONCLUSION

Children with bruxism showed signs and symptoms of TMDs and divergence in incisal relationships.

Classification of bruxism based on time-frequency and nonlinear features of single channel EEG

BACKGROUND

In the classification of bruxism patients based on electroencephalogram (EEG), feature extraction is essential. The method of using multi-channel EEG fusing electrocardiogram (ECG) and Electromyography (EMG) signal features has been proved to have good performance in bruxism classification, but the classification performance based on single channel EEG signal is still understudied. We investigate the efficacy of single EEG channel in bruxism classification.

METHODS

We have extracted time-domain, frequency-domain, and nonlinear features from single EEG channel to classify bruxism. Five common bipolar EEG recordings from 2 bruxism patients and 4 healthy controls during REM sleep were analyzed. The time domain (mean, standard deviation, root mean squared value), frequency domain (absolute, relative and ratios power spectral density (PSD)), and non-linear features (sample entropy) of different EEG frequency bands were analyzed from five EEG channels of each participant. Fine tree algorithm was trained and tested for classifying sleep bruxism with healthy controls using five-fold cross-validation.

RESULTS

Our results demonstrate that the C4P4 EEG channel was most effective for classification of sleep bruxism that yielded 95.59% sensitivity, 98.44% specificity, 97.84% accuracy, and 94.20% positive predictive value (PPV).

CONCLUSIONS

Our results illustrate the feasibility of sleep bruxism classification using single EEG channel and provides an experimental foundation for the development of a future portable automatic sleep bruxism detection system.

The bruxism screener (BruxScreen): Development, pilot testing and face validity

BACKGROUND

To assess awake and sleep bruxism, the Standardised Tool for the Assessment of Bruxism (STAB) is currently being developed. The STAB will be a comprehensive tool for the detailed assessment of bruxism behaviour itself as well as of its possible consequences, causes, and comorbid conditions.

OBJECTIVE

Since the STAB cannot fully meet the 'A4 principle' for a bruxism assessment tool, i.e., being Accurate (reliable and valid), Applicable (feasible), Affordable (cost-effective), and Accessible (suitable for everyday clinical use), the Bruxism Screener (BruxScreen) has been developed to be used in large-scale epidemiological research projects and, especially, in general, dental practices.

METHODS

The BruxScreen consists of two parts: a questionnaire (BruxScreen-Q) to be completed by patients, and a clinical assessment form (BruxScreen-C) to be completed by dentists.

RESULTS

This paper describes the development of the BruxScreen and provides the outcomes of the pilot testing phase and the face validity assessment (i.e. that the first impressions of the tool indicate that it adequately reflects the construct to be measured).

CONCLUSION

The resulting BruxScreen is considered ready for more profound psychometric testing in the general dental setting.

Sleep architecture as a candidate for phenotyping sleep bruxism: A narrative physiological review

BACKGROUND

Sleep bruxism (SB), an oral behaviour in otherwise healthy individuals, is characterised by frequent rhythmic masticatory muscle activity (RMMA) during sleep. RMMA/SB episodes occur over various sleep stages (N1-N3 and rapid eye movement (REM)), sleep cycles (non-REM to REM), and frequently with microarousals. It currently remains unclear whether these characteristics of sleep architecture are phenotype candidates for the genesis of RMMA/SB.

OBJECTIVES

This narrative review investigated the relationship between sleep architecture and the occurrence of RMMA as a SB phenotype candidate.

METHODS

PubMed research was performed using keywords related to RMMA/SB and sleep architecture.

RESULTS

In non-SB and SB healthy individuals, RMMA episodes were most frequent in the light non-REM sleep stages N1 and N2, particularly during the ascending phase of sleep cycles. The onset of RMMA/SB episodes in healthy individuals was preceded by a physiological arousal sequence of autonomic cardiovascular to cortical activation. It was not possible to extract a consistent sleep architecture pattern in the presence of sleep comorbidities. The lack of standardisation and variability between subject complexified the search for specific sleep architecture phenotype(s).

CONCLUSION

In otherwise healthy individuals, the genesis of RMMA/SB episodes is largely affected by oscillations in the sleep stage and cycle as well as the occurrence of microarousal. Furthermore, a specific sleep architecture pattern cannot be confirmed in the presence of sleep comorbidity. Further studies are needed to delineate sleep architecture phenotype candidate(s) that contribute to the more accurate diagnosis of SB and treatment approaches using standardised and innovative methodologies.

Occurrence, presence and severity of bruxism and its association with altered state of consciousness in individuals with severe acquired brain injury

BACKGROUND

Excessive jaw muscle activity is a frequent complication after acquired brain injury (ABI).

OBJECTIVE

The study aimed to identify the occurrence and severity of jaw muscle activity and its association with altered state of consciousness in patients with ABI.

METHODS

A total of 14 severe ABI patients with varied altered state of consciousness were recruited. A single-channel electromyographic (EMG) device was used to assess the jaw muscle activity for three consecutive nights during Week 1 and Week 4 following admission. Differences in number of EMG episodes/h between Week 1 and 4 were analysed using non-parametric tests and association between the EMG activity and altered state of consciousness were analysed using Spearman's correlation test.

RESULTS

Nine of fourteen (64%) patients showed indications of bruxism (cutoff: >15 EMG episodes/h). The average EMG episodes/h at admission were 44.5 ± 13.6 with no significant changes after Week 4 of admission (43 ± 12.9; p = .917). The EMG episodes/h ranged from 2 to 184 during Week 1 and 4-154 during Week 4. There were no significant correlations between the number of EMG episodes/h during the three nights and the individuals altered state of consciousness during Week 1 and Week 4.

CONCLUSION

Patients with ABI had a conspicuously high but variable level of jaw muscle activity at admission and it tend to remain high after 4 week of hospitalisation which could potentially lead to adverse effects such as excessive tooth wear, headaches and pain in jaw muscles. The lack of associations between individuals altered level of consciousness and EMG activity could be due to low sample size and further studies are clearly warranted in this patient group with special needs. Single-channel EMG devices can record jaw muscle activity early in the hospitalisation period and might be a helpful tools for early detection of bruxism in ABI patients.

Awake bruxism in temporomandibular disorders patients referred to tertiary care: A retrospective study on its assessment and TMD management

BACKGROUND

Bruxism is defined as a repetitive jaw-muscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Bruxism can occur during sleep (sleep bruxism, SB) or during wakefulness (awake bruxism, AB). To date, the effect of AB on the purported negative consequences of bruxism has remained unclear.

OBJECTIVES

The assessment of AB, its relation to temporomandibular disorders (TMD) treatment modalities, and their possible outcomes were investigated among TMD patients resistant to treatment in primary care and referred to a tertiary care clinic.

METHODS

The records of 115 patients were studied. Patients were referred to the Head and Neck Centre, Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, for TMD treatment between 2017 and 2020. The data derived from the eligible patients' records included the following: background data (age and sex), referral data (reason and previous treatment), medical background (somatic and psychiatric), clinical and possible radiological diagnoses at a tertiary care clinic, treatment modalities for masticatory muscle myalgia, bruxism assessment, its possible treatment modalities and their outcomes, and overall management outcome. We analysed the outcomes of single treatment modalities and combined groups of modalities. For the demographic data, the Chi-squared test and Fischer's Exact test were used to determine the associations between the categorical variables. A Sankey-diagram was used to describe the flow of treatment.

RESULTS

Temporomandibular joint-pain-dysfunction syndrome (K07.60) was the most frequent single reason to refer a patient to tertiary care (17.4%). At referral, men had myalgia (M79.1) significantly more often (p = .034) than women. Similarly, men had depression (p = .002) more often and other psychiatric diagnoses (p = .034). At tertiary care, the presence of AB was assessed in 53.9%, and self-reported AB was recorded in 48.7%. In patients with possible AB, those who were prescribed neuropathic pain medication showed significantly less improvement in symptoms (p = .021) than those who underwent splint therapy (p = .009). Overall, half of the patients showed overall improvement in their TMD symptoms from the treatment combinations.

CONCLUSION

Despite several treatment modalities, only half of the patients showed improvement in their symptoms in the present study. A standardised assessment method encompassing all factors contributing to bruxism behaviours and their consequences is suggested.

Standardised Tool for the Assessment of Bruxism

OBJECTIVE

This paper aims to present and describe the Standardised Tool for the Assessment of Bruxism (STAB), an instrument that was developed to provide a multidimensional evaluation of bruxism status, comorbid conditions, aetiology and consequences.

METHODS

The rationale for creating the tool and the road map that led to the selection of items included in the STAB has been discussed in previous publications.

RESULTS

The tool consists of two axes, specifically dedicated to the evaluation of bruxism status and consequences (Axis A) and of bruxism risk and etiological factors and comorbid conditions (Axis B). The tool includes 14 domains, accounting for a total of 66 items. Axis A includes the self-reported information on bruxism status and possible consequences (subject-based report) together with the clinical (examiner report) and instrumental (technology report) assessment. The Subject-Based Assessment (SBA) includes domains on Sleep Bruxism (A1), Awake Bruxism (A2) and Patient's Complaints (A3), with information based on patients' self-report. The Clinically Based Assessment (CBA) includes domains on Joints and Muscles (A4), Intra- and Extra-Oral Tissues (A5) and Teeth and Restorations (A6), based on information collected by an examiner. The Instrumentally Based Assessment (IBA) includes domains on Sleep Bruxism (A7), Awake Bruxism (A8) and the use of Additional Instruments (A9), based on the information gathered with the use of technological devices. Axis B includes the self-reported information (subject-based report) on factors and conditions that may have an etiological or comorbid association with bruxism. It includes domains on Psychosocial Assessment (B1), Concurrent Sleep-related Conditions Assessment (B2), Concurrent Non-Sleep Conditions Assessment (B3), Prescribed Medications and Use of Substances Assessment (B4) and Additional Factors Assessment (B5). As a rule, whenever possible, existing instruments, either in full or partial form (i.e. specific subscales), are included. A user's guide for scoring the different items is also provided to ease administration.

CONCLUSIONS

The instrument is now ready for on-field testing and further refinement. It can be anticipated that it will help in collecting data on bruxism in such a comprehensive way to have an impact on several clinical and research fields.

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.

Research routes on awake bruxism metrics: Implications of the updated bruxism definition and evaluation strategies

BACKGROUND

With time, due to the poor knowledge on it epidemiology, the need to focus on awake bruxism as a complement of sleep studies emerged.

OBJECTIVE

In line with a similar recent proposal for sleep bruxism (SB), defining clinically oriented research routes to implement knowledge on awake bruxism (AB) metrics is important for an enhanced comprehension of the full bruxism spectrum, that is better assessment and more efficient management.

METHODS

We summarised current strategies for AB assessment and proposed a research route for improving its metrics.

RESULTS

Most of the literature focuses on bruxism in general or SB in particular, whilst knowledge on AB is generally fragmental. Assessment can be based on non-instrumental or instrumental approaches. The former include self-report (questionnaires, oral history) and clinical examination, whilst the latter include electromyography (EMG) of jaw muscles during wakefulness as well as the technology-enhanced ecological momentary assesment (EMA). Phenotyping of different AB activities should be the target of a research task force. In the absence of available data on the frequency and intensity of wake-time bruxism-type masticatory muscle activity, any speculation about the identification of thresholds and criteria to identify bruxers is premature. Research routes in the field must focus on the improvement of data reliability and validity.

CONCLUSIONS

Probing deeper into the study of AB metrics is a fundamental step to assist clinicians in preventing and managing the putative consequences at the individual level. The present manuscript proposes some possible research routes to advance current knowledge. At different levels, instrumentally based and subject-based information must be gathered in a universally accepted standardised approach.

The development of the Standardised Tool for the Assessment of Bruxism (STAB): An international road map

This paper summarises the background reasoning and work that led to the selection of the items included in the Standardised Tool for the Assessment of Bruxism (STAB), also introducing the list of items. The instrument is currently being tested for face validity and on-field comprehension. The underlying premise is that the different motor activities included in the bruxism spectrum (e.g. clenching vs. grinding, with or without teeth contact) potentially need to be discriminated from each other, based on their purportedly different aetiology, comorbidities and potential consequences. Focus should be on a valid impression of the activities' frequency, intensity and duration. The methods that can be used for the above purposes can be grouped into strategies that collect information from the patient's history (subject-based), from the clinical assessment performed by an examiner (clinically based) or from the use of instruments to measure certain outcomes (instrumentally based). The three strategies can apply to all aspects of bruxism (i.e. status, comorbid conditions, aetiology and consequences). The STAB will help gathering information on many aspects, factors and conditions that are currently poorly investigated in the field of bruxism. To this purpose, it is divided into two axes. Axis A includes the self-reported information on bruxism status and potential consequences (subject-based report) together with the clinical (examiner report) and instrumental assessment (technology report). Axis B includes the self-reported information (subject-based report) on factors and conditions that may have an etiological or comorbid role for bruxism. This comprehensive multidimensional assessment system will allow building predictive model for clinical and research purposes.

Sleep bruxism in children and adolescents-A scoping review

BACKGROUND AND OBJECTIVE

This review paper focuses on sleep bruxism (SB) in children and adolescents. It aims to assess the landscape of knowledge published in the last 20 years.

METHODS

A total of 144 relevant publications from 386 previously identified through Medline were included, of which 83 were on possible SB, 37 on probable SB, 20 on definite SB and 4 were non-applicable. The review places emphasis on the recent evidence on prevalence, pathophysiology, diagnosis and management of SB in children and adolescents, with special focus on probable and definitive SB.

RESULTS

The prevalence ranges from 5% to 50% depending on the age range and on the SB diagnosis (possible, probable or definitive). The pathophysiology is multifactorial, arousal associated and with behavioural problems and sleep disorders (obstructive sleep apnoea, snoring, nightmares) as risk factors, as well as respiratory conditions (allergies, oral breathing). Screening should include questionnaires and dental assessment. Instrumental recording is helpful to confirm diagnosis although more studies are needed to validate this approach in children. SB management includes controlling orofacial and dental consequences and assessing for any other comorbidity. Management options include occlusal splints, oral appliances (advancement mandibular), rapid maxillary expansion and some medications, although this last option is supported by limited evidences in children.

CONCLUSION

Suggestions of future topics in research are delivered to better understand comorbidities, diagnosis and management with improved outcomes compared to what is currently available.

Assessment of awake bruxism by a novel bruxism screener and ecological momentary assessment among patients with masticatory muscle myalgia and healthy controls

BACKGROUND

Bruxism is a masticatory muscle activity occurring during sleep or wakefulness, involving grinding and clenching of teeth and/or jaw bracing. As yet, the aetiology, epidemiology and consequences of awake bruxism (AB) are largely unknown.

OBJECTIVES

The aims of the study were to AB behaviours using a novel bruxism screener (BruxScreen) questionnaire part and Ecological Momentary Assessment (EMA; BruxApp©) on AB behaviours, and to investigate AB's prevalence among masticatory muscle myalgia patients and non-patients.

METHODS

Altogether, 115 participants (masticatory myalgia patients referred to a specialist clinic (n = 67) and non-patients (n = 46)) filled in a bruxism screener questionnaire to report bruxism behaviours and jaw symptoms. A selection of both groups did a week-long EMA (patients n = 12, non-patients n = 11) to report AB behaviours. The chi-squared test was used to determine group differences in categorical variables. A logistic regression model was fitted to study the probability of AB.

RESULTS

According to BruxScreen, bruxism behaviours and jaw symptoms were more frequent in patients than in non-patients (p < .001). Based on EMA, 14.6% of the behaviour in patients was tooth clenching; for non-patients, this was 0.5% (p < .000). Relaxed muscles were reported by patients and non-patients at 20.6% and 56.4%, respectively (p < .021). Logistic regression, adjusted by age and sex, revealed that patients reported AB 5 times more often than non-patients (OR 4.8, 95% CI 2.1-11.2).

CONCLUSION

Awake bruxism behaviours are significantly more frequent in masticatory muscle myalgia patients than non-patients and associate with frequent bruxism-related symptoms. Self-reported teeth clenching seems to be the most significant sign of AB behaviour.

Salivary signatures of oral-brain communication in sleep bruxers

Introduction

Microbiota and their interaction with hosts have been of great interest in brain research in recent years. However, the role of oral microbiota in mental illness and the underlying mechanism of oral-brain communication remains elusive. Sleep bruxism (SB) is an oral parafunctional activity related to the nervous system and is considered a risk factor for harmful clinical consequences and severe systemic conditions. Exploring the connection between oral microbiota and sleep bruxism may deepen our understanding of the complex relationship between oral-brain axis and provide insights for treatment.

Methods

In this study, salivary samples were collected from 22 individuals with SB and 21 healthy controls, and metagenomics with metabolomics was performed. Nonparametric Wilcoxon test were applied for the statistical analysis between the two groups. Microbial dysbiosis and altered oral metabolites were found in the SB individuals.

Results

The characteristic metabolite N-acetylglucosamine (GlcNAc) (VIP=8.4823, P<0.05) was correlated to a statistically lower Streptococcus mitis level in SB individuals. Salivary IFN-g level and IFN-g/IL-4 ratio were detected with significant changes in a chip assay. Amino acid metabolism pathways were upregulated, and the pathway with the largest number of differentially expressed genes is related to amino-tRNA charging pathway, while the most significantly enriched pathway is related to arginine biosynthesis. Neurotransmitter-associated pathways with glutamatergic and GABAergic synapses and cardiovascular system-related pathways were enriched in the SB group.

Discussion

These results indicate a possible neuroimmune regulatory network of oral-brain communication in SB, which helps explain the mechanism of the oral microbiome with the host in sleep bruxers and provides a reference for early clinical and therapeutic intervention to improve the diagnosis and treatment of SB and similar diseases.

Evaluation of the relationship between sleep bruxism and sleeping habits in school-aged children

OBJECTIVE

To evaluate the relationship between sleep habits and sleep bruxism (SB) in schoolaged children.

METHODS

Survey data were collected from the parents of 500 children (267 males and 233 females; age range 6-12 years). The American Academy of Sleep Medicine diagnostic criteria were used to evaluate SB. A Children's Sleep Habits Questionnaire was conducted to determine sleep habits. The chi-square test was used for statistical evaluation.

RESULTS

SB was observed in 160 children (32%). SB awareness was 5.4%. The presence of SB in other family members, mothers' education ≤8 years, and income below minimum wage were found as family risk factors. The presence of sleep disorders was 61.4% and observed to be statistically higher in those with SB.

CONCLUSION

SB is a prevalent disorder that might be associated with sleep disorders. The parents of children with SB had inadequate knowledge and awareness pertaining to SB.

The continuous adverse impact of COVID-19 on temporomandibular disorders and bruxism: comparison of pre- during- and post-pandemic time periods

INTRODUCTION

Some of the conditions affected by the COVID-19 pandemic were Temporomandibular Disorders (TMD) and bruxism. The present study compares the effect of the pandemic on TMD and bruxism (sleep and awake) in three time periods: before the pandemic (pre-COV), during the pandemic (during-COV) and after the pandemic subsided (post-COVR).

MATERIAL AND METHODS

A total of 587 adult patients (108 in the pre-COV group, 180 in the during-COV group and 252 in the post-COVR group) who arrived for a routine dental treatment between October 2018 and January 2023 were evaluated according to Axis I diagnosis of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Each patient received a DC/TMD Axis I diagnosis as follows: (i) Painful TMD (defined by the presence of at least one of the following - local myalgia, myofascial pain with referral, arthralgia or headache attributed to TMD); (ii) Non painful TMD (defined by the presence of disc displacement with/without reduction, degenerative joint disorders and/or dislocation), (iii) Possible sleep bruxism (SB) and/or (iv) Possible awake bruxism (AB).

STATISTICAL METHODS

Logistic regression analyses were conducted to establish the impact of time and gender on the prospects of painful TMD, non-painful TMD, SB and AB.

RESULTS

The odds of subjects to be diagnosed with painful TMD at the post-COVR era were 3.3 times higher compared to the pre-pandemic time period (pre-COV, 95% C.I. 1.438-7.585). The odds of subjects to be diagnosed with non-painful TMD during-COV were 4 times higher compared to the pre-COV era (95% C.I. 1.332-12.542). The odds of subjects to present possible SB at post-COVR were 2.7 times higher compared to pre-pandemic (pre-COV, 95% C.I. 1.258-5.889, p < 0.05) and the odds to present possible AB after the pandemic subsided (post-COVR) were 3.2 times compared to the pre-pandemic period (95% C.I. 1.496-6.949). The odds of female subjects to be diagnosed with either painful or non-painful TMD were 3.7-4.4 times higher, compared to males.

CONCLUSIONS

Results indicate that with regard to TMD and bruxism the pandemic adverse effects persist also after COVID-19 subsides and the restrictions caused by it are abolished. Apparently, during the pandemic females were affected more seriously by painful and non-painful TMD than males.

Investigation of the relationship between probable sleep bruxism, awake bruxism and temporomandibular disorders using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)

BACKGROUND

The causal relationship between bruxism and temporomandibular disorders (TMD) is not clear.

OBJECTIVES

The present study investigated which TMD are associated with probable sleep bruxism (SB) and awake bruxism (AB) according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). The study further evaluated the association between probable SB and AB and TMD.

MATERIAL AND METHODS

A total of 143 patients were selected - bruxers (SB and AB) and non-bruxers. A diagnosis of probable bruxism was made after a physical examination and when the symptoms were detected. The patients were evaluated using DC/TMD. From among Axis I assessment instruments, the TMD Pain Screener, the Symptom Questionnaire and the Clinical Examination Form were used. Moreover, the Graded Chronic Pain Scale (GCPS) (v. 2), the Jaw Functional Limitation Scale-8 (JFLS-8), the Patient Health Questionnaire-4 (PHQ-4), and the Oral Behaviors Checklist (OBC) were applied within the scope of Axis II.

RESULTS

Diagnoses of muscle disorders and disk displacement with reduction were significantly more frequent in the SB and AB groups than in non-bruxers. A diagnosis of arthralgia was significantly more prevalent in the AB group than in non-bruxers. The JFLS-8 scores and the TMD Pain Screener scores were higher in the AB group than in the SB group and in non-bruxers. Distress levels, and the GCPS and OBC scores were higher in the SB and AB groups as compared to non-bruxers. The results of binary logistic regression analysis showed that only the OBC score was significantly higher in the TMD subgroup (OR (odds ratio) = 1.228; 95% CI (confidence interval): 1.014-1.488).

CONCLUSIONS

Both SB and AB were associated with pain-related TMD and intra-articular joint disorders. The muscle disorders and disk displacement with reduction subtypes were associated with SB and AB. Unlike SB, AB was also associated with arthralgia. Bruxers (both SB and AB) displayed parafunctional habits. However, AB was associated with greater functional limitation of the jaw as compared to SB.

Is camera recording crucial for the correct diagnosis of sleep bruxism in polysomnography?

Due to potential issues, several sleep laboratories conduct sleep bruxism diagnosis without the use of a camera, instead relying mostly on electromyographic monitoring. The purpose of the study was to determine if a camera is necessary for the polysomnographic evaluation of sleep bruxism and how sleep bruxism parameters change when a camera is not utilised. The study material was actual polysomnographic recordings made in the years 2017-2020. A total of 199 single-night video-polysomnographic recordings of patients who were suspected of having sleep bruxism were chosen at random. The first analysis involved the evaluation of the video recording, while in the second video recording was not used. The findings revealed that all the examined sleep bruxism indices had statistically significantly higher values for the recordings made without the use of a camera. According to the findings, noncamera recordings had decreased sensitivity and specificity when the criteria of bruxism and mild-to-moderate bruxism were taken into account, and decreased sensitivity in the case of the criterion of severe bruxism. Sleep efficiency, the apnea/hypopnea index, and arousals had independent effects on the bruxism episode index value in the analysis of noncamera recordings. In conclusion, camera-based polysomnography still appears to be the most reliable way to assess the severity of sleep bruxism, particularly in patients who also report other sleep disturbances. The presence of symptoms of sleep-disordered breathing, insomnia, or other sleep disorders should prompt us to use camera-based diagnostics.

Associations between signs of sleep bruxism and insomnia: A polysomnographic study

Sleep bruxism (SB) is a repetitive jaw-muscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Sleep bruxism has been linked with insomnia symptoms. Moreover, it has been suggested that there is a positive association between distress and the occurrence of sleep bruxism. However, the occurrence of sleep bruxism and its association with distress have not been studied in patients with insomnia. Therefore, we hypothesised that: (1) the occurrence of sleep bruxism is higher in patients with insomnia than in healthy controls; and (2) the occurrence of sleep bruxism in insomnia patients with moderate to high distress (IMHD) is higher than that in insomnia patients with slight distress (ISD). A total of 44 controls (34 females, 10 males, mean ± SD age = 46.8 ± 14.4 years) and 42 participants with insomnia (35 females, 7 males, mean ± SD age = 51.3 ± 12.1 years) were enrolled in this study. Among 42 participants with insomnia, 20 participants were subtyped as IMHD, 17 participants as ISD. Another five participants were not subtyped due to insufficient information. Group differences in rhythmic masticatory muscle activity (RMMA), a biomarker of sleep bruxism, were evaluated with Mann-Whitney U tests. The medians and interquartile ranges of the RMMA indices were 0.8|1.8|3.3 in controls, 1.1|1.6|2.3 in IMHD and 1.2|1.9|2.9 in ISD. There was no significant difference in the RMMA index, neither between participants with insomnia and controls (P = 0.514) nor between IMHD versus ISD (P = 0.270). The occurrence of RMMA indicators of possible sleep bruxism is not significantly different between individuals with insomnia and controls, nor between IMHD versus ISD.

Diagnosis and prevalence of probable awake and sleep bruxism in adolescents: an exploratory analysis

The aims of this study were to perform an exploratory analysis of probable awake (AB) and sleep bruxism (SB) prevalence using of different diagnosis criteria based on the International Consensus; evaluate the associations between self-report and clinical signs/symptoms in adolescents. Participated in this cross-sectional study 403 adolescents aged 12- to 19-years-old enrolled in public and private schools from Belo Horizonte, Brazil. Parents/caregivers answered a questionnaire about sociodemographic status and adolescents' health status. Adolescents answered a questionnaire evaluating AB (e.g., grinding and clenching) and SB (e.g., grinding, bracing, and thrusting) activities and frequent headaches. A clinical examination was performed on adolescents to evaluate bruxism clinical signs/symptoms (pain upon palpation on masseter and temporal, linea alba, indentation on the tongue and attrition wear severity). Descriptive statistics and Pearson's Qui-square test were performed (P≤0.05). Adolescents mean age was 14.3±1.5 years, and 58.1% were female. Self-report of SB was identified in 31% of participants and self-report of AB in 51.6%. Almost all adolescents (99%) presented at least one tooth with attrition wear (98.5% on enamel and 0.5% on dentin), with a mean number of 12.4±5.7 teeth. Depending on the diagnosis criteria, the prevalence of probable SB and AB varied from 0- 99% and 0.2- 99%, respectively. A high inconsistency was found for the prevalence of probable AB and SB in adolescents, which were influenced by the different clinical sings/symptoms used as diagnosis criteria. Frequent headaches and pain upon palpation on masseter and temporal muscle were associated to self-report of AB and SB among adolescents.

Sleep bruxism is highly prevalent in adults with obstructive sleep apnea: a large-scale polysomnographic study

STUDY OBJECTIVES

The aim was to determine the prevalence and risk factors of sleep bruxism (SB) and to investigate the relationships between SB episodes, arousals, and respiratory events in adults with obstructive sleep apnea (OSA).

METHODS

This prospective study included 914 adults with OSA (305 females, 609 males; age = 53 years [interquartile range = 17]; apnea-hypopnea index = 13.9 events/h [interquartile range = 21]). The diagnosis of SB was made when the rhythmic masticatory muscle activity (RMMA) index was at least 2 episodes/h of sleep based on a full polysomnographic recording. Binary logistic regression was performed to identify risk factors for SB. Network analysis was performed to determine the relations between RMMA, respiratory event, sleep arousal, and other factors. Further, the percentage of RMMA time-related to arousal was calculated.

RESULTS

The prevalence of SB in adults with OSA was 49.7%. Male sex, lower body mass index, and higher percentage of N1 sleep increased the odds of having SB (odds ratios = 1.425, 0.951, and 1.032, respectively; all P < .05). Network analysis showed that there were no direct associations between RMMA and apnea-hypopnea index, nor between RMMA and arousal, although 85.7% of RMMA was time-related to arousals.

CONCLUSIONS

Nearly half of adults with OSA have comorbid SB. Male sex, lower body mass index, and a higher percentage of light sleep increase the risk of having SB. Although RMMAs do not directly correlate with respiratory events and arousals, most RMMAs are time-related to arousals in adults with OSA.

CLINICAL TRIAL REGISTRATION

Registry: Netherlands Trial Register; Name: A Large Sample Polysomnographic Study on Sleep Bruxism; URL: https://trialsearch.who.int/Trial2.aspx?TrialID=NL8516; Identifier: NL8516.

CITATION

Li D, Kuang B, Lobbezoo F, de Vries N, Hilgevoord A, Aarab G. Sleep bruxism is highly prevalent in adults with obstructive sleep apnea: a large-scale polysomnographic study. J Clin Sleep Med. 2023;19(3):443-451.

Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity

STUDY OBJECTIVES

This study investigated the diagnostic accuracy of Sleep Profiler, which relies on ambulatory polysomnography (PSG) with electroencephalogram for sleep bruxism (SB) and examined its episode-by-episode agreement in comparison to PSG equipped with audiovisual recordings (avPSG).

METHODS

This prospective 2-gate study recruited 10 individuals with probable SB and 10 healthy volunteers. Overnight experimental recordings were performed simultaneously using the ambulatory PSG with masseter electromyography and avPSG with masseter and temporalis electromyography. Sleep staging was performed manually for avPSG and automatically or manually for ambulatory PSG. SB episodes were manually scored based on electromyography signals with reference to sleep stages. The episode-by-episode agreement was analyzed by setting avPSG as the reference standard. The sensitivity, specificity, and accuracy for the diagnosis of SB were calculated after optimizing the cutoff values of the episode index and the burst index.

RESULTS

Regarding the episode-by-episode agreement, median sensitivities were 0.825 and positive predictive values were approximately 0.6, regardless of the sleep staging procedure, indicating that approximately 40% of the overall total SB episodes scored by the ambulatory PSG were false positives. Because of overestimation of SB episodes, the optimal cutoff values for the episode index and the burst index were approximately 1.5 times higher than the avPSG-based cutoff values and dramatically improved the diagnostic precision metrics for the ambulatory PSG.

CONCLUSIONS

Sleep Profiler can eliminate events during wakefulness by electroencephalogram and may provide a definitive diagnosis in patients with possible SB by applying optimized cutoff values. However, the risk of overestimation must be recognized.

CLINICAL TRIAL REGISTRATION

Registry: UMIN Clinical Trials Registry; Name: Accuracy of Portable PSG Device for Detection of Sleep Bruxism-Related Masseter EMG Muscle Activity; URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000037380; Identifier: UMIN000032793.

CITATION

Abe Y, Nakazato Y, Takaba M, Kawana F, Baba K, Kato T. Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity. J Clin Sleep Med. 2023;19(2):379-392.

Prevalence of painful temporomandibular disorders, awake bruxism and sleep bruxism among patients with severe post-traumatic stress disorder

BACKGROUND

Post-traumatic stress disorder (PTSD) is associated with painful temporomandibular disorder (TMD) and may be part of the aetiology of awake bruxism (AB) and sleep bruxism (SB). Investigating the associations between PTSD symptoms on the one hand, and painful TMD, AB and SB on the other, can help tailoring treatment to the needs of this patient group.

OBJECTIVES

The aim of this study was to investigate the associations between PTSD symptoms and painful TMD, AB and SB among patients with PTSD, focusing on prevalence, symptom severity and the influence of trauma history on the presence of painful TMD, AB and SB.

METHODS

Individuals (N = 673) attending a specialised PTSD clinic were assessed (pre-treatment) for painful TMD (TMD pain screener), AB and SB (Oral Behaviours Checklist), PTSD symptoms (Clinician-Administered PTSD Scale) and type of traumatic events (Life Events Checklist).

RESULTS

Painful TMD, AB and SB were more prevalent among patients with PTSD (28.4%, 48.3% and 40.1%, respectively) than in the general population (8.0%, 31.0% and 15.3%, respectively; all p's < .001). PTSD symptom severity was found to be significantly, but poorly, associated with the severity of painful TMD (rs  = .126, p = .001), AB (rs  = .155, p < .001) and SB (rs  = .084, p = .029). Patients who had been exposed to sexual assault were more likely to report AB than patients who had not. Similarly, exposure to physical violence was associated with increased odds for SB.

CONCLUSION

Patients with severe PTSD are more likely to experience painful TMD, AB or SB, whereas type of traumatic event can be of influence. These findings can contribute to selecting appropriate treatment modalities when treating patients with painful TMD, AB and SB.

Bruxist Activity Monitor System (BAMS): An instrumental approach tool in the assessment of Bruxism

The magnitude of harmful effects on dental structures, periodontium, masticatory muscles, and the temporomandibular joint, derived from temporomandibular disorders, specifically from sleep Bruxism, generates evidence that needs to be objectively collected. This paper introduces a portable device aiming at extracting and analyzing parameters (like timestamp, duration, or latency) from recordings obtained from the monitoring of occlusal activity, throughout a complete sleep cycle. An electronic device embedded in a mid-density medical grade silicon occlusal splint detects the moment in which the subject exerts sustained force, and records the time and length of the event, keeping the device on hold until a new event arises. The electronic device, based on a microcontroller, identifies occlusive events from an array of two piezo-resistive sensors and has a storage capacity of up to 36 hours of continuous activity. The collected data is wirelessly transmitted to an external module that is connected via USB to a PC. In the PC, the data is decoded, processed, analyzed, displayed, and stored in ordered files for case subjects, updating every recorded test for a complete history review. The proposed Bruxist Activity Monitor System (BAMS) was tested in one subject for more than 40 hours (5 sessions in 7 days). Preliminary results show the oral appliance endure without any significant damage over its surface nor undermining its functionality.

Sleep Bruxism in Children: Etiology, Diagnosis, and Treatment-A Literature Review

(1) Background: Bruxism, a condition characterized by grinding and involuntary clenching of the teeth, is a risk factor for the development of masticatory dysfunction. It can occur together with sleep disturbances and may be associated with abnormal body movements, breathing difficulties, increased muscle activity, and heart rate disturbances. This disorder is becoming an important dental concern in children. (2) Methods: A literature review was carried out based on a search in PubMed and Google Scholar databases for articles on bruxism in children, published between 2014 and 2021. The etiology, diagnosis, and treatment of bruxism in children were of particular interest in the study. (3) Results: A total of 40 articles were included in the review. The analyzed studies indicated that the prevalence rates of bruxism in children vary widely from 13% to 49%. The etiology of bruxism is complex and incomprehensible, and the main diagnostic criteria for this condition in children are subjective observation, clinical history, and clinical examination. The recommended therapy for sleep bruxism in children is physiotherapy and psychotherapy. (4) Conclusions: Dentists and primary care physicians should correctly diagnose bruxism in children, educate parents, prevent potential consequences for oral health, and identify possible comorbidities. Appropriate clinical guidelines for the treatment and prophylaxis of bruxism in children should also be developed.

Association Between Primary Headache and Bruxism: An Updated Systematic Review

AIMS

To answer the question: among observational studies, is there any association between primary headaches and bruxism in adults?

MATERIALS AND METHODS

A systematic review of observational studies was performed. The search was performed in seven main databases and three gray literature databases. Studies in which samples were composed of adult patients were included. Primary headaches were required to be diagnosed by the International Classification of Headache Disorders. Any diagnostic method for bruxism was accepted. Risk of bias was evaluated using the Joanna Briggs Institute Critical Appraisal Tool and the Meta-Analysis of Statistics Assessment and Review Instrument (MAStARI) tool. Associations were analyzed by calculating odds ratios (OR) in Review Manager 5.3 software. The evidence certainty was screened by Grading of Recommendations Assessment, Development, and Evaluation criteria.

RESULTS

Of the 544 articles reviewed, 5 met the inclusion criteria for qualitative analysis. The included studies evaluated both awake and sleep bruxism, as well as tension-type headaches and migraines as primary headaches. Among two migraine studies, one showed an OR of 1.79 (95% CI: 0.96 to 3.33) and another 1.97 (95% CI: 1.5 to 2.55). On the other hand, among three tension-type headache studies, there was a positive association only with awake bruxism, with an OR of 5.23 (95% CI: 2.57 to 10.65). All included articles had a positive answer for more than 60% of the risk of bias questions. The evidence certainty varied between low and very low. Due to high heterogeneity among the studies, it was impossible to perform a meta-analysis.

CONCLUSION

Patients with awake bruxism have from 5 to 17 times more chance of having tension-type headaches. Sleep bruxism did not have any association with tension-type headache, and the association with migraines is controversial.

Bruxism definition: Past, present, and future - What should a prosthodontist know?

STATEMENT OF PROBLEM

The definition of bruxism has evolved, and the dental profession needs to align with the terminologies adopted in the current literature of sleep and orofacial pain medicine.

PURPOSE

The purpose of this review was to discuss the recent evolution of bruxism concepts and the implications for changing the definition that is currently used by the prosthodontic community.

MATERIAL AND METHODS

A historical perspective on the evolution of the definition of bruxism, as well as a systematic literature review on the validity of polysomnography (PSG)-based criteria for sleep bruxism diagnosis to detect the presence of clinical consequences, is presented. Selected articles were read in a structured Population, Intervention, Comparison, Outcome (PICO) format to answer the question "If a target population with conditions such as tooth wear, dental implant complications, and temporomandibular disorders (P) is diagnosed with sleep bruxism by means of PSG (I) and compared with a population of nonbruxers (C), is the occurrence of the condition under investigation (that is, the possible pathologic consequences of sleep bruxism) be different between the 2 groups (O)?"

RESULTS

Eight studies were eligible for the review, 6 of which assessed the relationship between PSG-diagnosed sleep bruxism and temporomandibular disorder pain, while the other 2 articles evaluated the predictive value of tooth wear for ongoing PSG-diagnosed sleep bruxism and the potential role of sleep bruxism in a population of patients with failed dental implants. Findings were contradictory and not supportive of a clear-cut relationship between sleep bruxism assessed based on available PSG criteria and any clinical consequence. The literature providing definitions of bruxism as a motor behavior and not pathology has been discussed.

CONCLUSIONS

The bruxism construct has shifted from pathology to motor activity with possibly even physiological or protective relevance. An expert panel including professionals from different medical fields published 2 consecutive articles focusing on the definition of bruxism, as well as an overview article presenting the ongoing work to prepare a Standardized Tool for the Assessment of Bruxism (STAB) to reflect the current bruxism paradigm shift from pathology to behavior (that is, muscle activity). As such, dental practitioners working in the field of restorative dentistry and prosthodontics are encouraged to appraise this evolution.

[Bruxism: Classification, Diagnostics and Treatment]

Bruxism: Classification, Diagnostics and Treatment Abstract. Bruxism, the grinding or clenching of teeth, is common in the population. Stress, anxiety syndromes and genetic disposition seem to be dominant factors that lead to increased muscle tension. A distinction is made between two circadian manifestations, sleep and wake bruxism. Bruxism is a major risk factor for tooth structure and dentures. The diagnosis is based on a targeted medical history and examination. Sleep bruxism can be demonstrated by electromyography and video recording in the sleep laboratory. The treatment aims to protect the hard tooth substance and preserve the denture using occlusal splints. Relaxation exercises can improve bruxism. Specialized physiotherapy can improve tension, pain and restricted movement. Botulinum toxin treatment reduces the subjective complaints during the period of action.

The effectiveness of stabilization appliance therapy among patients with myalgia

BACKGROUND

The efficacy of stabilization appliance therapy for masticatory muscle pain is debated. Therefore, there are currently no clear usage standards. We analyzed patient factors influencing its efficacy and characterized masticatory muscle pain subtypes to determine appropriate therapy candidates.

METHODS

This case series study recruited patients diagnosed with local myalgia or myofascial pain and used variables related to temporomandibular disorders in the analysis. We used temporary appliance to screen patients for sleep bruxism for 2 weeks. Afterwards, we initiated therapy with stabilization appliances. Efficacy was evaluated via tenderness intensity during muscle palpation and the treatment satisfaction score after 2 months of treatment.

RESULTS

We analyzed 62 (91%) patients. Tenderness upon muscle palpation was mitigated in 27 patients. Mitigated tenderness odds ratios were 0.035 for myofascial pain, 0.804 for 15-item Patient Health Questionnaire scores, and 1.915 for facet length. Thirty-nine patients expressed satisfaction; satisfaction odds ratios were 0.855 for 9-item Patient Health Questionnaire scores, 1.606 for facet length, and 4.023 for awake bruxism awareness.

CONCLUSIONS

Stabilization appliance therapy is most effective for patients with awake bruxism awareness, local myalgia, long facets, and no psychosocial risk factors.

Polysomnographic scoring of sleep bruxism events is accurate even in the absence of video recording but unreliable with EMG-only setups

PURPOSE

To determine the accuracy of scoring masticatory muscle activity (MMA) events in seven different polysomnography (PSG) setups.

METHODS

Nineteen volunteers (13 females, 6 males, age 31.1 ± 12.9 years, 12 self-proclaimed bruxers) attended one-night PSG recording, supplemented with audio, video, and a separate frontal electroencephalography electrode set (FES). The same examiner scored the MMA events with seven different setups, with varying number of channels available: (1) one, (2) two, and (3) four EMG channels, (4) PSG without audio or video (PSG-N), (5) home PSG with FES and audio (FES-A), (6) PSG with audio (PSG-A), and (7) PSG with audio and video (PSG-AV). A subset (n = 10) of recordings was scored twice to determine intra-scorer reliability. MMA indices and accuracy of scoring the events in different setups were compared against PSG-AV.

RESULTS

The intra-class correlation coefficient (ICC) between PSG-AV and PSG-A was high (0.940, p < 0.001) as well as for FES-A (0.927, p < 0.001), whereas for PSG-N, it was lower (0.835, p < 0.001); for setups with only EMG channels, coefficients were very low (ICC < 0.100 for all). Intra-examiner reliability was high (ICC > 0.939 for all setups), with the exception of PSG-N (ICC = 0.764, p = 0.002). When comparing against the MMA events scored in PSG-AV, the sensitivity of MMA event recognition for PSG-A was 78.5% and specificity 95.5%, which were substantially higher than sensitivity (52.0%) and specificity (87.2%) of PSG-N.

CONCLUSIONS

MMA event scoring accuracy with PSG-A or FES-A is almost comparable to PSG-AV. Since precise event recognition is essential for accurate MMA scoring, it is evident that one cannot rely exclusively on EMG.

Home Polysomnography Reveals a First-Night Effect in Patients With Low Sleep Bruxism Activity

STUDY OBJECTIVES

To examine the presence of a first-night effect (FNE) and the level of internight variability in sleep bruxism (SB) activity when a self-applicable electrode set is used in home polysomnography (PSG) in a sample of subjects with possible SB.

METHODS

Fourteen females and two males aged 38.3 ± 9.1 years (mean ± standard deviation) with self-reported SB underwent home-PSG on three consecutive nights. The subjects applied PSG sensors themselves, including self-applicable electrode sets used to record sleep and masseter muscle activity. Repeated-measures analysis of variance was used to compare SB and sleep variables between the nights.

RESULTS

Surprisingly, there were statistically significant elevations in the rhythmic masticatory muscle activity (RMMA) episode index (P = .009), burst index (P = .016), and bruxism time index (P = .049) throughout the course of 3 nights. More bruxers were diagnosed on the second (6 bruxers, ≥ 2 episodes/h) and third night (7 bruxers) compared to the first night (2 bruxers). Most subjects (14/16) had their highest RMMA index on the second or third night. The mean coefficient of variation for RMMA episode index was 50.7%. No statistically significant differences were detected in other sleep variables.

CONCLUSIONS

The results indicate that a FNE may be present in SB activity, possibly lasting several nights in some subjects. Furthermore, FNE appears to be combined with high internight variability of SB activity without indications of internight changes in sleep macrostructure. To confirm the level of ongoing SB activity, several nights of PSG may be required, especially in subjects with low first-night SB activity.

COMMENTARY

A commentary on this article appears in this issue on page 1281.

[Sleep bruxism : state of the art and management]

Although well studied since the 50's, bruxism remains a largely unknown pathology. Its origin is complex, mixing psychological as well as neurological, odontological and hypnic aspects. However, the few analyzes performed on this topic have allowed to set convincing etiopathological hypotheses, including central dysregulation of the dopaminergic system as well as of the neuro-masticatory system. To avoid harmful consequences as headaches, temporomandibular disorders and premature dental scuffs / fractures, it is mandatory to diagnose bruxism as early as possible. For this purpose, and in addition to anamnestic and clinical data, the practitioner can confirm diagnosis with polysomnography, including electromyographic study of masticatory muscles and audiovisual recording. Some orthodontic, pharmacological and psychological solutions have already proved efficient. Nevertheless, a better knowledge of causative neurobiological mechanisms would allow to foresee etiology-based treatments.

Success Rate and Technical Quality of Home Polysomnography With Self-Applicable Electrode Set in Subjects With Possible Sleep Bruxism

Using sleep laboratory polysomnography (PSG) is restricted for the diagnosis of only the most severe sleep disorders due to its low availability and high cost. Home PSG is more affordable, but applying conventional electroencephalography (EEG) electrodes increases its overall complexity and lowers the availability. Simple, self-administered single-channel EEG monitors on the other hand suffer from poor reliability. In this study, we aimed to quantify the reliability of self-administrated home PSG recordings conducted with a newly designed ambulatory electrode set (AES) that enables multichannel EEG, electrooculography, electromyography, and electrocardiography recordings. We assessed the sleep study success rate and technical quality of the recordings performed in subjects with possible sleep bruxism (SB). Thirty-two females and five males aged 39.6 ± 11.6 years (mean±SD) with self-reported SB were recruited in the study. Self-administrated home PSG recordings with two AES designs were conducted (n = 19 and 21). The technical quality of the recordings was graded based on the proportion of interpretable data. Technical failure rate for AES (both designs) was 5% and SB was scorable for 96.9% of all recorded data. Only one recording failed due to mistakes in self-applying the AES. We found that the proportion of good quality self-administrated EEG recordings is significantly higher when multiple channels are used compared to using a single channel. Sleep study success rates and proportion of recordings with high quality interpretable data from EEG channels of AES were comparable to that of conventional home PSG. Self-applicable AES has potential to become a reliable tool for widely available home PSG.

Identification of a Sleep Bruxism Subgroup with a Higher Risk of Pain

Sleep bruxism research diagnostic criteria (SB-RDC) have been applied since 1996. This study was performed to validate these criteria and to challenge the hypothesis that pain is associated with lower frequencies of orofacial activities. Polygraphic recordings were made of 100 individuals presenting with a clinical diagnosis of sleep bruxism and 43 control individuals. TwoStep Cluster analyses (SPSS) were performed with sleep bruxism variables to reveal groupings among sleep bruxers and control individuals. Participants completed questionnaires during screening, diagnosis, and recording sessions. Cluster analysis identified three subgroups of sleep bruxers. Interestingly, 45 of the 46 sleep bruxers with values below SB-RDC were classified in the low-frequency cluster. These individuals were more likely to complain of pain and fatigue of masticatory muscles than were the higher-frequency sleep bruxers (odds ratios > 3.9, p < 0.01). Sleep bruxers were distributed among three heterogeneous groups. Sleep bruxers with low frequencies of orofacial activities were more at risk of reporting pain.

Multi-sources data analysis with sympatho-vagal balance estimation toward early bruxism episodes detection

Sleep bruxism events detection system is presented, based on integrated, synchronized on-line analysis of EMG signal, heart rave variability (HRV) obtained from ECG recordings as well as sympatho-vagal balance estimated in real time as an possible early indicator of upcoming bruxism episodes. As an relative reliable alternative for very complex systems, only for clinical environment usage with audio and video recordings a pilot study toward elaboration of compact, comfortable for home usage device with early bruxism detection algorithms was carried out, preliminary tested on 10h sleeping registrations from group of 12 patients, clinically characterized by experts as Bruxers. As a result a set of decision rules regarding simultaneous monotonic increase of heart rate with significant increase of EMG signal amplitude during bruxism episode was elaborated. But a most promising observation, which can be useful for earlier prediction of upcoming bruxism episode seems to be a monotonic increase of LF/HF ratio in HRV power spectrum components, expressing sympatho-vagal balance of autonomous nervous system, which according to our assumptions take basic low level role in bruxism phenomena trigger and control.

Sleep medicine content in dental hygiene education

According to the National Research Council, 70 million Americans chronically suffer from approximately 60 medically recognized sleep disorders. With most clinicians unaware of these disorders, many individuals remain undiagnosed. To effectively address this issue, health care professionals must work collaboratively to educate, identify, and treat patients with sleep disorders. However, medical and dental clinicians do not receive adequate education in sleep medicine. On the frontline regarding prevention and counseling, dental hygienists play an important role in patient education, screening, and management of sleep disorders. The aim of this study was to assess the amount of sleep medicine content in U.S. dental hygiene programs. An electronic survey was emailed to all 334 accredited U.S. dental hygiene programs. The 18-question survey assessed the sleep medicine content presented during the 2012-13 academic year. A total of 35.3% (n=118) of the programs responded. The mean number of hours devoted to sleep medicine in their curricula was 1.55 hours (SD=1.37). Although 69% (n=79) of the responding programs reported spending time on sleep bruxism (mean=1.38 hours, SD=0.85), only 28% (n=32) reported spending time on other topics such as snoring and obstructive sleep apnea (mean=1.39 hours, SD=0.72). These results suggest that sleep medicine is included in the majority of U.S. dental hygiene programs, but the content is limited and focused on sleep bruxism. This level of training is inadequate to prepare dental hygienists for their potential role in patient education, screening, and management of sleep-related breathing disorders.

Polysomnographic analysis of bruxism

The American Academy of Sleep Medicine (AASM) defines sleep bruxism as a stereotyped movement disorder characterized by clenching and grinding of the teeth during sleep. Bruxism is found in 14%-20% of children, 8% of adults <60 years old, and 3% of adults >60 years old. The mandibular movements of bruxism can be confused with rhythmic mandibular movements associated with other sleep disorders, such as arousals/microarousals, limb movement disorder, and obstructive sleep apnea/hypopnea syndrome. Polysomnography (PSG) is the study of sleep disorders based on the recording of physiological events throughout an entire night of sleep. This system involves electroencephalography, electrooculography, and electromyography of the submental/suprahyoid, tibialis anterior, mentalis, masseter, and temporal muscles, through which signs of sleep bruxism can be identified. The aim of the present study was to identify bruxism during a night of sleep in a laboratory. Thirty patients were analyzed clinically and underwent PSG. The descriptive analysis correlated apnea, arousals, and limb movements in the 12 patients who exhibited signs and symptoms of sleep bruxism. Of these patients, 4 were confirmed through PSG to have bruxism. In a comparison between the 4 patients with confirmed bruxism (PSGB group) and the 8 patients confirmed not to have bruxism (NPSGB group), the respiratory event index was lower in the PSGB group (13.17 and 17.95, respectively). The mean leg movement index was higher in the PSGB group than the NPSGB group in total sleep time (21.36 and 8.42, respectively) and in rapid eye movement sleep time (34.54 and 10.30, respectively).

Sleep bruxism: review and update for the restorative dentist

Sleep bruxism (SB) is a parafunctional oromotor activity that can sometimes pose a threat to the integrity of the structures of the masticatory system if the magnitude and direction of the forces exerted exceed the system's adaptive capacity. Over the years science has tried to provide a consistent explanation of the etiopathogenesis and physiopathology of SB, although the pathophysiological mechanisms are, even now, not fully understood yet. There is at present no specific, effective treatment to permanently eliminate the habit of SB. There are only palliative therapeutic alternatives steered at preventing the pathological effects of SB on the stomatognathic system and alleviating the negative clinical consequences of the habit. The aim of this paper is to review and update the fundamental scientific concepts of SB based on the scientific literature and to furnish an approach to the main types of therapy available, in an attempt to assist the general and restorative dentist to manage those clinical situations in which SB is a significant risk factor for the oral health and/or dental treatment of the patient.

Community based study of sleep bruxism during early childhood

OBJECTIVES

The aims for this study were to determine the prevalence of sleep-bruxism among young children, explore child behavior problems that may be associated with sleep-bruxism, and identify relations among sleep-bruxism, health problems, and neurocognitive performance.

METHODS

The current study was a retrospective analysis of parent report surveys, and behavioral and neurocognitive assessments. Parents of 1953 preschool and 2888 first grade children indicated their child's frequency of bruxism during sleep. A subsample of preschool children (n=249) had additional behavioral, as well as neurocognitive assessments. Among the subsample, parents also reported on their child's health, and completed the Child Behavioral Checklist; children were administered the Differential Ability Scales, and Pre-Reading Abilities subtests of the Developmental Neuropsychological Assessment.

RESULTS

36.8% of preschoolers and 49.6% of first graders were reported to brux ⩾1time per week. Among the preschool subsample, bruxing was independently associated with increased internalizing behaviors (β=.17). Bruxism was also associated with increased health problems (β=.19), and increased health problems were associated with decreased neurocognitive performance (β=.22).

CONCLUSIONS

The prevalence of sleep-bruxism was high. A dynamic and potentially clinically relevant relation exists among sleep-bruxism, internalizing behaviors, health, and neurocognition. Pediatric sleep-bruxism may serve as a sentinel marker for possible adverse health conditions, and signal a need for early intervention. These results support the need for an interdisciplinary approach to pediatric sleep medicine, dentistry, and psychology.

Tooth wear in young subjects: a discriminator between sleep bruxers and controls?

PURPOSE

This study investigated whether the presence of tooth wear in young adults can help to discriminate patients with sleep bruxism (SB) from control subjects.

MATERIALS AND METHODS

The tooth wear clinical scores and frequency of sleep masseter electromyographic activity of 130 subjects (26.6 +/- 0.5 years) were compared in this case-control study. Tooth wear scores (collected during clinical examination) for the incisors, canines, and molars were pooled or analyzed separately for statistics. Sleep bruxers (SBrs) were divided into two subgroups according to moderate to high (M-H-SBr; n = 59) and low (L-SBr; n = 48) frequency of masseter muscle contractions. Control subjects (n = 23) had no history of tooth grinding. The sensitivity and specificity of tooth wear versus SB diagnosis, as well as positive and negative predictive values (PPV and NPV), were calculated. One-way analysis of variance and the Mann-Whitey U test were used to compare groups.

RESULTS

Both SBr subgroups showed significantly higher tooth wear scores than the control group for both pooled and separated scores (P < .001). No difference was observed between M-H-SBr and L-SBr frequency groups (P = .14). The pooled sum of tooth wear scores discriminates SBrs from controls (sensitivity = 94%, specificity = 87%). The tooth wear PPV for SB detection was modest (26% to 71%) but the NPV to exclude controls was high (94% to 99%).

CONCLUSIONS

Although the presence of tooth wear discriminates SBrs with a current history of tooth grinding from nonbruxers in young adults, its diagnostic value is modest. Moreover, tooth wear does not help to discriminate the severity of SB. Caution is therefore mandatory for clinicians using tooth wear as an outcome for SB diagnosis.