Sleep hygiene measures combined with mindfulness meditation in the management of sleep bruxism in children: A randomized controlled clinical trial

BACKGROUND

Sleep hygiene measures and meditation may reduce stress and improve sleep quality, but their effect on the occurrence of sleep bruxism in children has not yet been investigated.

AIM

To explore the effects of sleep hygiene measures combined with mindfulness meditation (relaxation audio) in the management of probable sleep bruxism (SB) in children.

DESIGN

This clinical trial (no. NCT04501237) randomized 36 children with 3-8 years of age. Probable SB detection was performed according to the criteria established by the International Consensus on The Assessment of Bruxism-2018. Intervention group was instructed to practice sleep hygiene measures and mindfulness meditation (i.e., the use of a digital app to broadcast audio relaxation) each night before bedtime for 5 weeks; control group did not receive guidance for therapies. Parents completed a bruxism diary for 5 weeks, and the outcome was the number of SB episodes-day reported in the week (ranging from 0 to 7) in each period. A multilevel mixed-effects Poisson regression model was performed.

RESULTS

A total of 32 children (mean age: 6.1 years) completed the study. The children who received the therapies related to sleep hygiene measures and mindfulness meditation had a reduction in the SB incidence rate ratio (IRR) of 46% (IRR = 0.54 [Confidence Interval 95%, 0.45-0.65]) during a 5-week observation period. The sensitivity analyses did not show relevant changes in the measure of the effect.

CONCLUSION

Sleep hygiene measures combined with mindfulness meditation reduced the SB in children.

Prevalence and risk factors of sleep bruxism in adults with primary snoring: a large-scale polysomnographic study

STUDY OBJECTIVES

To determine the prevalence and risk factors of sleep bruxism (SB) in adults with primary snoring (PS).

METHODS

This study included 292 adults with PS (140 males, 152 females; mean age ± SD = 42.8 ±12.2 years; mean BMI ± SD = 26.7 ± 4.7 kg/m2) without previous treatment for snoring. SB was diagnosed based on the frequency of the biomarker of SB: rhythmic masticatory muscle activity (RMMA; SB when RMMA ≥ 2 episodes/hour). Logistic regression was performed, with SB as the dependent variable and with age, sex, BMI, and sleep- and respiratory-related polysomnographic parameters as the independent variables to identify the risk factors for SB.

RESULTS

The prevalence of SB was 44.6% in adults with PS. Younger age (OR = 0.965 [0.944, 0.987]) and shorter total sleep time (OR = 0.760 [0.609, 0.948]) significantly increased the risk of SB (P < 0.05).

CONCLUSIONS

SB is highly prevalent in adults with PS. Younger age and shorter sleep time are significant risk factors for SB in adults with PS.

CLINICAL TRIAL REGISTRATION

Registry: Netherlands Trial Register; Name: A Large Sample Polysomnographic Study on Sleep Bruxism; Identifier: NL8516.

The effect of sleep position on sleep bruxism in adults with obstructive sleep apnea

BACKGROUND

Most of the respiratory events in adults with obstructive sleep apnea (OSA) occurs in supine position. It has been reported that the contraction of masseter muscles is dependent on the occurrence of arousals rather than on the occurrence of respiratory events.

OBJECTIVES

This study had two aims: (1) to compare the rhythmic masticatory muscle activity (RMMA) index in supine position (RMMA_sup) and in non-supine positions (RMMA_nsup) in adults with OSA; and (2) to determine the associations between RMMA index in both supine position and non-supine positions on the one hand, and several demographic and polysomnographic variables on the other hand.

METHODS

One hundred OSA participants (36 females and 64 males; mean age = 50.3 years (SD = 10.5)) were selected randomly from among patients with a full-night polysomnographic recording. RMMA_sup index and RMMA_nsup index were compared using Mann-Whitney U-test. Multivariate linear regression analyses were used to predict RMMA index both in supine and non-supine positions based on several demographic and polysomnographic variables.

RESULTS

In patients with OSA, the RMMA_sup index was significantly higher than the RMMA_nsup index (p < .001). RMMA_sup index was significantly associated with the arousal index (p = .002) and arousal index in supine position (p < .001). RMMA_nsup index was only significantly associated with the arousal index in non-supine positions (p = .004).

CONCLUSION

Within the limitations of this study, RMMAs occur more frequently in supine position than in non-supine positions in patients with OSA. In both sleep positions, RMMAs are associated with arousals.

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.

Bridging semantics and medical ontology in the definition of bruxism: An argument for a holistic definition

OBJECTIVE

The objective of this commentary is to advocate for a holistic, ontology-based definition of bruxism. The intention is to synthesise the best aspects of current definitions into a structured ontological model, thereby refining and enhancing a comprehensive understanding of the full spectrum of bruxism.

MATERIALS AND METHODS

The commentary elaborates on the process of integrating these insights into a hierarchical ontology that aligns with ontological principles.

SETTINGS AND SAMPLE POPULATION

Not directly applicable as this is a commentary.

RESULTS/CONCLUSION

The proposed ontology-based definition of bruxism aims to clarify communication within the medical community and advance research by enabling a comprehensive ontology-based classification of bruxism. By aligning with ontological principles, this approach aspires to act as a catalyst for further research, discussion and consensus in the field.

Decrypting the putative interrelation between sleep bruxism, masticatory muscle pain and sleep breathing disorders: Nosology and the role of hypoxia

This commentary on sleep medicine explores whether the potential relationship between sleep bruxism (SB), masticatory muscle pain (MMP) and sleep breathing disorders (SBDs)contributes to improving the management of co-occurring conditions.The paper is divided into 2 sections: (1) reviewing the debate on SB nosology; and (2) based on the publications from the Martynowicz & Wieckiewicz research group, exploringthe role of intermittent hypoxia as a putative mechanism endotype that may link such co-occurrence among individuals for whom characteristics are not yet clear.

Probable sleep and awake bruxism in adolescents: A path analysis

BACKGROUND

Bruxism has a multifactorial etiology, including the influence of sleep characteristics and chronotypes.

AIM

To identify the pathways that influence the occurrence of probable sleep bruxism (PSB) and probable awake bruxism (PAB) in adolescents.

DESIGN

A total of 403 adolescents, aged 12-19 years, participated in the study. Parents/caregivers filled out a questionnaire about sociodemographic issues and the adolescent's health conditions, and the adolescents about sleep characteristics, occurrence of bruxism (based on previous study and the International Consensus of Bruxism), and chronotype (Circadian Energy Scale). Clinical examinations were performed. Statistical analysis included descriptive analysis and path analysis.

RESULTS

PSB and PAB are related to each other, with moderate and positive correlation (β = .390). Poor sleep quality and higher household income had a direct effect on both PSB (β = -.138; β = .123, respectively) and PAB (β = -.155; β = .116, respectively). Chronotype had a direct effect on PSB, in such a way that adolescents with a morningness chronotype tend to have PSB (β = -.102). Adolescents that drool on the pillow (β = .184) and/or have agitated sleep (β = .104) tend to have PSB.

CONCLUSION

Poor sleep quality, household income, morningness chronotype profile, drooling on the pillow, and agitated sleep influence the paths taken by PSB. PAB was influenced by the quality of sleep and family income.

Short-Term Effects of 3D-Printed Occlusal Splints and Conventional Splints on Sleep Bruxism Activity: EMG-ECG Night Recordings of a Sample of Young Adults

(1) Background: This study aims to compare the effects of 3D-printed splints and conventional manufactured splints on sleep bruxism (SB) EMG activity. (2) Methods: Twenty-six patients (19 M, 7 F, 25.8 ± 2.6 years) were randomly allocated to a study group (3D splints) and a control group (conventional manufactured splints) and followed for a period of three months with night EMG-ECG recordings. Samples of the involved materials were analyzed for nanoindentation. The outcomes of interest considered were the overall SB index, the total amount of surface masseter muscle activity (sMMA), and general and SB-related phasic and tonic contractions. A statistical evaluation was performed with a confidence interval (CI) between 2.5% and 97.5%. (3) Results: Differences between groups with OAs were observed for general tonic contraction (p = 0.0009), while differences between recording times were observed for general phasic contractions (p = 0.002) and general tonic contractions (p = 0.00001). Differences between recording times were observed for the total amount of sMMA (p = 0.01), for general phasic contractions (p = 0.0001), and for general tonic contractions (p = 0.000009) during night recordings without OAs. (4) Conclusions: Three-dimensional splints seem to have a higher impact on SB-related electromyographic activity but not on the overall sleep bruxism index. The more regular surfaces offered by 3D splints could be related to phasic contraction stabilization.

Association between Psychological Distress and Possible, Probable, and Definite Sleep Bruxism-A Comparison of Approved Diagnostic Procedures

(1) Background: The relationship between sleep bruxism (SB) and psychological distress has been investigated in numerous studies and is heterogeneous. Different diagnostic procedures have been applied to determine SB. The aim of this study was to directly compare the association between psychological distress and SB diagnosed by different accepted methods. (2) Methods: Data of N = 45 subjects were analyzed, including group comparisons and correlation analyses. Following diagnostic methods for the determination of SB were used in one sample: self-report, clinical assessment, polysomnography with audio-video recording and a novel diagnostic sheet with analyzing software. Psychological distress was measured using the global severity index (GSI) of the Symptom Checklist-90-Standard (SCL-90-S). (3) Results: The GSI did not differ significantly between subjects with and without SB, regardless of the underlying diagnostic classification (p > 0.05). In-depth correlation analyses of self-report and clinical data revealed a weak-to-medium correlation with the GSI (r = 0.12-0.44). Due to non-normally distributed data, a test of statistical significance was not possible. Variables of instrumental methods such as the SB index (amount of SB activity per hour) of polysomnography (PSG) showed almost no correlation with psychological distress (r = -0.06-0.05). (4) Conclusions: Despite these limitations, the results provide an indication that the choice of diagnostic procedure may elucidate the variance in the correlation between SB and psychological distress.

Association between perfectionism, personality traits and probable sleep bruxism in Spanish schoolchildren: A case-control study

BACKGROUND

The aetiology of Sleep bruxism includes specific personality traits, related to perfectionism.

AIM

To investigate the relationship between probable sleep bruxism (PSB) and personality traits in children and their parents, determining whether children with PSB and their parents are more perfectionists.

DESIGN

This case-control study included 104 children aged 8-9 years, 52 cases and 52 controls. A clinical examination was performed on the children who completed the Big Five Personality Questionnaire (BFQ-NA) and the Child Perfectionism Inventory. Parents completed a bruxism diagnostic questionnaire according to the AASM criteria, BFQ and Frost multidimensional perfectionism scale questionnaires. t-Tests for independent samples and multivariate logistic regression models were used for statistical analysis.

RESULTS

A significant relationship between PSB and a self-demanding personality (OR = 1.11, p = .01), restless sleep (OR = 4.41, p = .004), and a family history of clenching and grinding teeth (OR = 3.07, p = .0006) was found in a binary logistic regression model. When adjusted, only restless sleep showed a significant relationship with PSB (p = .03, OR 3.32, 95% CI 1.13-9.81).

CONCLUSION

Children whose parents reported as clenching or grinding their teeth while asleep in the previous 6 months, and who were found to have abnormal dental wear, had significantly more nightmares, sleep disruption, daytime sleepiness, family history of bruxism, and tended to be more perfectionist.

Self-reported sleep bruxism in 1990 and 2011 in a nationwide twin cohort: Evidence of trait persistence and genetic liability

BACKGROUND

Due to different assessment modes employed, a clear picture of the prevalence of sleep bruxism across time cannot be formed. Moreover, studies on the persistent or fluctuating nature of sleep bruxism have yielded divergent and even contradictory results. The aim of the present study was to evaluate in a nationwide twin cohort whether self-reported sleep bruxism was correlated longitudinally, pairwise and cross-twin over a 20-year period.

OBJECTIVES

Self-reported bruxism was assessed in 1990 and 2011 by mailed questionnaires in the Finnish Twin Cohort study of same-sex twins born 1945-1957.

METHODS

We assessed the phenotypic stability over time for all participating individuals (n = 4992). Among zygosity verified pairs (n = 516 MZ and n = 837 DZ), we estimated the cross-sectional zygosity correlations and the zygosity-specific cross-twin cross-time correlations.

RESULTS

Reported bruxism appeared rather persistent over time without significant difference regarding zygosity. The overall phenotypic longitudinal correlation was 0.540 and somewhat higher in men (0.596) than in women (0.507). Pairwise trait correlations in 1990 and 2011 were higher in MZ than in DZ pairs. The cross-twin cross-time correlations were higher in MZ twins than in DZ twins, but less than the cross-sectional MZ and DZ pairwise correlations.

CONCLUSIONS

The higher correlation of reported sleep bruxism in the cross-twin cross-time analyses in MZ than in DZ pairs implies a genetic background for bruxism persistence. Also, bruxism over time in individual twins appears to be fairly persistent and somewhat higher in men than women.

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.

Correlations between sleep architecture and sleep-related masseter muscle activity in children with sleep bruxism

BACKGROUND

Sleep bruxism (SB) occurring during No-REM (nREM) sleep and increase in microarousals per hour have been described in adults, but not in children.

OBJECTIVE

To assess the correlation between sleep architecture and masseter muscle activity related to sleep bruxism (SB/MMA) in children.

MATERIALS AND METHODS

Forty-three children aged 7-12 years (mean age: 9.4 ± 1.3) with confirmed SB underwent a two-night polysomnographic (PSG) study in a sleep laboratory, for accommodation (first night) and data collection (second night). Data on sleep architecture (total sleep duration (TSD), sleep efficiency (SE), sleep onset latency (SOL), REM and nREM sleep duration and proportion and microarousals/hour during REM and nREM sleep) and episodes/hour of SB/MMA were recorded. Single and multiple-variable linear regression analyses were performed to assess the correlation between data on sleep architecture (predictors) and SB/MMA (dependent variable).

RESULTS

Shorter TSD, REM and nREM stage 1 sleep duration, longer SOL and more microarousals/hour during REM and nREM sleep were found to be positive predictors of SB/MMA in children in the multiple-variable regression analysis (R2  = 0.511).

CONCLUSION

Within the limitations of this study, it can be concluded that SB/MMA is correlated with altered sleep architecture in children (shorter total sleep duration (TSD), shorter nREM and REM sleep and higher microarousals during REM and nREM sleep). Nevertheless, the clinical significance of these findings need to be demonstrated in future studies.

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.

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.

Reciprocal first night effect on rhythmic and non-rhythmic oromotor episodes in moderate to severe primary sleep bruxism: A retrospective physiological study

BACKGROUND

Sleep on the first night in a sleep laboratory is characterized by a lower sleep quality and frequency of rhythmic masticatory muscle activity (RMMA) than that on the second night in moderate to severe sleep bruxism (SB) patients.

OBJECTIVE

The aims of this study was to clarify the physiological factors contributing to the first night effect on oromotor activity during sleep and investigate whether physiological factors involved in the first night effect differed between rhythmic and non-rhythmic oromotor activities.

METHODS

Polysomnographic data collected on two consecutive nights from 15 moderate to severe SB subjects (F 7: M 8; age: 23.2 ± 1.3 [mean ± SD] years) were retrospectively analysed. Sleep variables, RMMA and non-specific masticatory muscle activity (NSMA) were scored in relation to episode types (i.e. phasic or tonic and cluster or isolated), sleep architecture and transient arousals. The relationships between nightly differences in oromotor and sleep variables were assessed. The distribution of oromotor events, arousals, cortical electroencephalographic power, RR intervals and heart rate variability were examined in relation to sleep cycle changes. These variables were compared between the first and second nights and between RMMA and NSMA.

RESULTS

Sleep variables showed a lower sleep quality on Night 1 than on Night 2. In comparisons with Night 1, the RMMA index increased by 18.8% (p  < .001, the Wilcoxon signed-rank test) on Night 2, while the NSMA index decreased by 17.9% (p  = .041). Changes in the RMMA index did not correlate with those in sleep variables, while changes in the NSMA index correlated with those in arousal-related variables (p  < .001, Spearman's rank correlation). An increase in the RMMA index on Night 2 was found for the cluster type and stage N1 related to sleep cyclic fluctuations in cortical and cardiac activities. In contrast, the decrease in the NSMA index was associated with increases in the isolated type and the occurrence of stage N2 and wakefulness regardless of the sleep cycle.

CONCLUSION

Discrepancies in first night effect on the occurrence of RMMA and NSMA represent unique sleep-related processes in the genesis of oromotor phenotypes in SB subjects.

Self-reported sleep bruxism and mortality in 1990-2020 in a nationwide twin cohort

BACKGROUND

The association of sleep bruxism with mortality has not been studied.

OBJECTIVES

Altogether 12 040 subjects from the nationwide Finnish twin cohort were included in the analyses. We examined whether self-reported sleep bruxism is associated with increased risk of mortality, and if so, whether the effect is independent of known common risk factors. The time span of the follow-up was 30 years.

METHODS

Cox proportional hazards regression models (Hazard Ratios and their 95% Confidence Intervals) adjusted by age, sex and covariates were used to assess the effect of baseline bruxism status in 1990 on future mortality in 1990-2020.

RESULTS

The risk of mortality among all participants (n = 12 040), independent of missing covariates and adjusted by age and sex, was 40% higher in weekly bruxers than in never bruxers (HR 1.40, 95% CI 1.16-1.68, p < .001). However, when adjusted by all studied covariates, (n = 11 427) the risk was no longer observed (HR 1.04, 95% CI 0.86-1.25, p = .717). Despite the overall lack of between bruxism and mortality after adjustment for covariates, we examined the cause-specific risks for major cause-of-death groups. There were no substantial associations of weekly bruxism with major disease outcomes by the fully adjusted hazard ratios for them.

CONCLUSION

Bruxism does not kill-in line with its definition of being rather a behaviour (with all its phenotypes) than a disease.

A worldwide bibliometric analysis of the research trends and hotspots of bruxism in adults during 1991-2021

BACKGROUND AND OBJECTIVES

With the increasing attention to bruxism, the research on bruxism is increasing rapidly. However, there is still a lack of systematic bibliometric analysis in the field of bruxism in adults. This study aimed to comprehensively explore and visualize the global trends and research hotspots in the field of bruxism in adults during 1991-2021.

METHODS

The study searched the literature published during 1991-2021 in the Web of Science Core Collection database without language restrictions. VOSviewer, CiteSpace and Microsoft Excel were applied to analyse the authors, institutions, journals, countries, cited references, keywords and other information of the included publications, and construct visualized cooperation networks.

RESULTS

A total of 878 articles were finally included. The top two most productive authors in the past 30 years were Lobbezoo F and Manfredini D. ACTA-Amsterdam, Univ Sao Paulo, Univ Helsinki, Univ Padua, Univ Montreal, et al. were prominent institutions in this field. Journal of Oral Rehabilitation made outstanding contributions in this field. The United States produced the most documents in this field, followed by Brazil. Both countries and authors cooperated closely around the world. The two most cited articles focused on the definition, assessment and classification of bruxism. In recent years, diagnostic criteria and stress have begun to receive a lot of attention.

CONCLUSION

From 1991 to 2021, the attention to bruxism in adults continued to increase. Diagnostic criteria and stress may be potential research hotspots in this field. This study references relevant scholars on development trends and research hotspots.

The relationship between possible, probable, or definite sleep bruxism and sleep quality: A systematic review

It has been suggested that sleep bruxism may interrupt sleep continuity, hence potentially influencing sleep quality. The aim of this study was to systematically review the relationship between possible, probable, and definite sleep bruxism and sleep quality in otherwise healthy individuals. A systematic search on sleep bruxism and sleep quality was performed in seven databases until 19 December 2022. Eligible articles were screened, and quality assessment was performed via the Joanna Briggs Institute Scale. Of 3681 articles screened, 13 were included in this study. Of these, six evaluated the relationship between sleep quality and possible sleep bruxism, three with probable sleep bruxism, and four with definite sleep bruxism. An association between poor sleep quality and sleep bruxism was found among those individuals diagnosed with possible and probable sleep bruxism. However, the studies conducted in individuals with definite sleep bruxism failed to demonstrate any association. With more reliable measures to evaluate sleep bruxism, a relationship between sleep bruxism and sleep quality was not evident.

The association of self-reported awake bruxism and sleep bruxism with temporomandibular pain and dysfunction in adult patients with temporomandibular disorders

OBJECTIVE

To investigate the association of the severity of temporomandibular disorders (TMD) pain and dysfunction with the frequency of self-reported awake bruxism (AB), sleep bruxism (SB), and stress in an adult TMD-patient population.

MATERIALS AND METHODS

This cross-sectional study included 237 TMD patients based on the Diagnostic Criteria for TMD. Age, sex, frequency of self-reported AB and SB, and stress were included as independent variables. TMD pain and TMD dysfunction were included as dependent variables in regression analyses. Univariate and multivariable linear regression analyses were used to predict TMD pain and TMD dysfunction in two separate models. Finally, network analysis was performed to investigate the associations between all variables.

RESULTS

In the univariate analyses, TMD pain was significantly associated with self-reported AB-frequent (unstandardized coefficient (B) = 3.196, 95%CI 1.198-5.195, p = 0.002). TMD dysfunction was significantly associated with AB-frequent (B = 2.208, 95%CI 0.177-4.238, p = 0.033) and SB-sometimes (B = 1.698, 95%CI 0.001-3.394, p = 0.050). In the multivariable analyses, TMD pain was significantly associated with TMD dysfunction (B = 0.370, p < 0.001), stress (B=0.102, p < 0.001). TMD dysfunction was significantly associated with TMD pain (B = 0.410, p < 0.001) only. Network analysis showed that TMD pain is a bridge factor between AB, stress, and TMD dysfunction.

CONCLUSIONS

TMD pain is directly associated with AB, stress, and TMD dysfunction, while TMD dysfunction is only associated with TMD pain.

CLINICAL RELEVANCE

Reducing pain may improve pain-related dysfunction, and the management of AB and stress may improve TMD pain and dysfunction, and vice versa.

Diagnostic Accuracy of a Portable Electromyography and Electrocardiography Device to Measure Sleep Bruxism in a Sleep Apnea Population: A Comparative Study

BACKGROUND

The gold standard for diagnosing sleep bruxism (SB) and obstructive sleep apnea (OSA) is polysomnography (PSG). However, a final hypermotor muscle activity often occurs after apnea episodes, which can confuse the diagnosis of SB when using portable electromyography (EMG) devices. This study aimed to compare the number of SB episodes obtained from PSG with manual analysis by a sleep expert, and from a manual and automatic analysis of an EMG and electrocardiography (EKG) device, in a population with suspected OSA.

METHODS

Twenty-two subjects underwent a polysomnographic study with simultaneous recording with the EMG-EKG device. SB episodes and SB index measured with both tools and analyzed manually and automatically were compared. Masticatory muscle activity was scored according to published criteria. Patients were segmented by severity of OSA (mild, moderate, severe) following the American Academy of Sleep Medicine (AASM) criteria. ANOVA and the Bland-Altman plot were used to quantify the agreement between both methods. The concordance was calculated through the intraclass correlation coefficient (ICC).

RESULTS

On average, the total events of SB per night in the PSG study were (8.41 ± 0.85), lower than the one obtained with EMG-EKG manual (14.64 ± 0.76) and automatic (22.68 ± 16.02) analysis. The mean number of SB episodes decreases from the non-OSA group to the OSA group with both PSG (5.93 ± 8.64) and EMG-EKG analyses (automatic = 22.47 ± 18.07, manual = 13.93 ± 11.08). However, this decrease was minor in proportion compared to the automatic EMG-EKG analysis mode (from 23.14 to 22.47). The ICC based on the number of SB episodes in the segmented sample by severity degree of OSA along the three tools shows a moderate correlation in the non-OSA (0.61) and mild OSA (0.53) groups. However, it is poorly correlated in the moderate (0.24) and severe (0.23) OSA groups: the EMG-EKG automatic analysis measures 14.27 units more than PSG. The results of the manual EMG-EKG analysis improved this correlation but are not good enough.

CONCLUSIONS

The results obtained in the PSG manual analysis and those obtained by the EMG-EKG device with automatic and manual analysis for the diagnosis of SB are acceptable but only in patients without OSA or with mild OSA. In patients with moderate or severe OSA, SB diagnosis with portable electromyography devices can be confused due to apneas, and further study is needed to investigate this.

Publication performance and trends in bruxism research: A bibliometric analysis

BACKGROUND

Bruxism is an umbrella term that encompass a multidimensional spectrum of masticatory muscle activities.

OBJECTIVE

The purpose of this study was to do a bibliometric analysis including citation performance in the research topic of bruxism, by using an innovative method including details of article title, author keyword, KeyWords Plus and abstracts.

METHODS

The data were retrieved 2022-12-19 from the Clarivate Analytics Web of Science Core Collection, and the online version of the Science Citation Index Expanded (SCI-EXPANDED) for studies published 1992 to 2021. To evaluate research trends, the distribution of keywords in the article title and author-selected keywords were used.

RESULTS

The search yielded 3233 documents in SCI-EXPANDED, of which 2598 were of the document-type 'articles' published in 676 journals. The analysis of the articles revealed that "bruxism/sleep bruxism," "electromyography," "temporomandibular disorders" and "masticatory muscles" are the most used keywords by the authors. Further, the most frequently cited study was published 9 years ago and handles the present definition of bruxism.

CONCLUSION

The most productive authors and those with the highest performance have some common features; they have several national and international collaborations; and they have published articles about the definition, aetiology/pathophysiology and prevalence of bruxism, all senior researchers in the field of TMD. Hopefully, based on this study, researchers and clinicians will have information to be stimulated to outline future research projects on bruxism-related aspects, and to initiate new international or multinational collaborations.

A case-control study on the effect of rhythmic masticatory muscle activity (RMMA) clusters on sleep fragmentation and severity of orofacial muscle pain in sleep bruxism

Rhythmic masticatory muscle activity (RMMA) is a periodic muscle activity that characterises sleep bruxism (SB) events. These can occur as a single event, in pairs, or in clusters. Since RMMA episodes often occur in clusters and the relevance of this occurrence is unknown, we conducted a study to investigate the effect of RMMA clusters on sleep fragmentation and the severity of orofacial muscle pain. This study involved a secondary analysis using data from 184 adult subjects with orofacial muscle pain who underwent definitive polysomnography (PSG) for sleep bruxism diagnosis. Self-reported orofacial muscle pain (OFMP) was assessed using the numeric rating scale, and additional evaluation of side-to-side equivalence (symmetry) was described using a binary system. Among the 184 participants, 60.8% (n = 112) did not exhibit clusters and among the 72 participants with clusters, 36.1% (n = 26) and 63.9% (n = 46) were in the high and low RMMA frequency groups, respectively. The high SB group had significantly three times more phasic RMMA events than the noncluster group. A total of 89.67% (n = 165) of subjects reported orofacial muscle pain. While there was no difference in the severity of OFMP among groups, a significant decrease in symmetry between the severity of temporal muscle pain on the left and right sides was noted in the cluster group compared with the noncluster group. Clustering of RMMA events is associated with sleep fragmentation. The asymmetry of temporal muscle pain is related to the presence of RMMA clusters in sleep bruxism.

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.

Impact of the COVID-19 pandemic on sleep bruxism among adolescents in Brazil: A longitudinal study

AIM

To evaluate the immediate and late impact of the COVID-19 pandemic on the occurrence of possible sleep bruxism (SB) among adolescents in Brazil.

DESIGN

This is a longitudinal study performed with adolescents (11-15 years old) from Southern Brazil. Baseline data were collected before the Brazilian COVID-19 outbreak (T1). Posteriorly, data were collected after 3 (T2) and 15 months under the Brazilian COVID-19 outbreak. The possible SB was evaluated by the question: 'Do you grind your teeth during your sleep?'. Sociodemographic, psychosocial and clinical variables were also collected. Changes in SB were evaluated by multilevel logistic regression models for repeated measures.

RESULTS

Of the 290 adolescents assessed at T1, 182 were reassessed at both follow-ups. The prevalence of possible SB was 13% at T1, 11% at T2 and 22% at T3. There were no immediate effects of the COVID-19 pandemic on the occurrence of possible SB (T2). Adolescents had odds 2.77 times greater of presented possible SB after 15 months (T3) of COVID-19 pandemic scenarios when compared to T1.

CONCLUSION

There was a considerable and late increase in the possible SB in adolescents in Brazil during the COVID-19 pandemic.

Temporomandibular Disorders at the Preoperative Time of Orthognathic Surgery

Individuals seeking orthodontic treatment combined with orthognathic surgery (OS) have a high prevalence of temporomandibular disorders (TMDs), but the relationship between TMD diagnoses and dentofacial deformities (DFDs) is still controversial. Therefore, this cross-sectional study with a comparison group aimed to analyze the association between dentofacial deformities and TMDs.

METHODOLOGY

Eighty patients undergoing OS were consecutively selected from the stomatology department of the Federal University of Paraná between July 2021 and July 2022. Forty patients who would undergo OS composed the group of participants with DFD, and forty who received other types of attention and did not present changes in the dental bone bases formed the group without DFDs (DFDs and no DFDs groups). The groups were matched for sex, age, and self-reported ethnicity. The diagnostic criteria for TMDs (DC/TMDs) were used to diagnose TMD based on the Axis I criteria. The psychosocial aspects, oral behaviors in wakefulness, and sleep bruxism were evaluated through the Axis II criteria. The data were analyzed with a 5% significance level.

RESULTS

The presence of DFDs was significantly associated with arthralgia (p = 0.01). The other types of TMDs were not associated with DFDs. Comorbidities, habits, and psychosocial variables were not associated with DFDs at a level of 0.05. (p > 0.05). In analyzing the participants with arthralgia, the ones with this condition presented higher frequencies of sleep bruxism (p = 0.046).

CONCLUSIONS

Participants with DFDs presented a significantly higher frequency of arthralgia when compared to no DFDs ones. Sleep bruxism was associated with the occurrence of joint TMDs in these participants.

Association Involving Possible Sleep Bruxism, Stress, and Depressive Symptoms in Brazilian University Students: A Cross-sectional Study

The aim of the present study was to examine the association regarding sleep bruxism (SB), depression, and stress in Brazilian university students. We conducted a cross-sectional study with a large-sample of university students ( n  = 2,089) in the city of Pelotas, Rio Grande do Sul, Southern Brazil. A self-administered questionnaire was sent to classrooms to evaluate socioeconomic and demographic characteristics. Possible SB was detected by self-report according to the International Consensus on The Assessment of Bruxism Criteria (2018). The Patient Health Questionnaire-9 and the Perceived Stress Scale were used to assess depression and stress symptoms respectively. Crude and adjusted Poisson regression analyses were performed. The prevalence of possible SB, high level of stress, and depressive symptoms in the sample were of 20.4%, 16.6%, and 16.6% respectively. Stress in female students was significantly associated with an increased prevalence of possible SB, but not in male students. Regarding depression, the prevalence of SB was 28% higher in students with depressive symptoms. Students with stress or depression had a 35% higher prevalence of SB than those without any symptoms. Conclusion  The findings have shown that university students with stress and depressive symptoms were more likely to be detected with possible SB.

Childhood and Adolescents Sleep Bruxism Treatment: A Systematic Review

Introduction  Sleep Bruxism (SB) is a common condition in childhood that can cause multiple consequences such as abnormal tooth wear, tensional headaches, masticatory muscle pain, or fatigue. The literature reports some interventions, however the treatment for SB in children is not well-established. Objectives  A systematic review was performed to investigate the effectiveness of the treatments described for SB in children and adolescents: pharmacological and psychological treatments; behavioral guidelines; and dental approaches. Materials and methods  Randomized clinical trials comparing different SB treatments with a control group were searched in the electronic databases PubMed, Scopus, Web of Science, Cochrane Library, and VHL until August 04, 2021. Two independent reviewers selected the studies, extracted the data, and assessed the risk of bias. After a two-phase selection process, 07 articles were selected. The methodology of the selected studies was analyzed using the Cochrane Risk of Bias Tool. The criteria used to qualify the studies were based on randomization, allocation, blinding of participants and evaluators, and analysis of results. Results  The signs and symptoms of SB were reduced with pharmacotherapy (hydroxyzine/diazepam) and medicinal extracts ( M. Officinalis ), but with occlusal splints and physiotherapy, this improvement was not statistically significant when compared to control groups. Conclusion  Some evidence of the efficacy of pharmacotherapy (hydroxyzine/diazepam) and medicinal extracts ( M. Officinalis ) was found. However, this systematic review is not enough to establish a protocol for the treatment of SB. Besides, the individualized management of SB in this population should be considered, emphasizing the management of risk factors.

The association between sleep bruxism and awake bruxism: Polysomnographic and electromyographic recordings in women with and without myofascial pain

BACKGROUND

Sleep bruxism (SB) and awake bruxism (AB) are masticatory muscle activities that are rarely assessed in the same individuals and are thought to be associated with different behaviours.

OBJECTIVES

To investigate whether individuals engaging in SB also engage in AB, that occurs during rest and during stress-related activity, and to investigate whether SB and AB are associated with different characteristics.

METHODS

Females with myofascial pain (N = 122) and non-myofascial pain controls (N = 46) were evaluated for SB events and for AB events at rest and AB during stress-related activity, using electromyographic (EMG) recordings and a standardised scoring of bruxism events. The joint distributions between SB and AB events and EMG activity were evaluated, and the characteristic qualities of SB and AB were assessed.

RESULTS

Neither SB event rates nor the EMG activity associated with those events was associated with AB events rates or EMG activity, either at rest or during stress-related activity. On the contrary, event rates and EMG activity when awake and at rest were positively associated with events and activity during stress-related activity. SB was characterised mainly by grinding, while AB was characterised mainly by clenching.

CONCLUSION

Sleep bruxism and awake bruxism do not tend to occur in the same individuals.

The Role of Emotion Regulation, Affect, and Sleep in Individuals With Sleep Bruxism and Those Without: Protocol for a Remote Longitudinal Observational Study

BACKGROUND

Sleep bruxism (SB) is an oral behavior characterized by high levels of repetitive jaw muscle activity during sleep, leading to teeth grinding and clenching, and may develop into a disorder. Despite its prevalence and negative outcomes on oral health and quality of life, there is currently no cure for SB. The etiology of SB remains poorly understood, but recent research suggests a potential role of negative emotions and maladaptive emotion regulation (ER).

OBJECTIVE

This study's primary aim investigates whether ER is impaired in individuals with SB, while controlling for affective and sleep disturbances. The secondary aim tests for the presence of cross-sectional and longitudinal mediation pathways in the bidirectional relationships among SB, ER, affect, and sleep.

METHODS

The study used a nonrandomized repeated-measures observational design and was conducted remotely. Participants aged 18-49 years underwent a 14-day ambulatory assessment. Data collection was carried out using electronic platforms. We assessed trait and state SB and ER alongside affect and sleep variables. We measured SB using self-reported trait questionnaires, ecological momentary assessment (EMA) for real-time reports of SB behavior, and portable electromyography for multinight assessment of rhythmic masticatory muscle activity. We assessed ER through self-reported trait questionnaires, EMA for real-time reports of ER strategies, and heart rate variability derived from an electrocardiography wireless physiological sensor as an objective physiological measure. Participants' trait affect and real-time emotional experiences were obtained using self-reported trait questionnaires and EMA. Sleep patterns and quality were evaluated using self-reported trait questionnaires and sleep diaries, as well as actigraphy as a physiological measure. For the primary objective, analyses will test for maladaptive ER in terms of strategy use frequency and effectiveness as a function of SB using targeted contrasts in the general linear model. Control analyses will be conducted to examine the persistence of the SB-ER relationship after adjusting for affective and sleep measures, as well as demographic variables. For the secondary objective, cross-sectional and longitudinal mediation analyses will test various competing models of directional effects among self-reported and physiological measures of SB, ER, affect, and sleep.

RESULTS

This research received funding in April 2017. Data collection took place from August 2020 to March 2022. In all, 237 participants were eligible and completed the study. Data analysis has not yet started.

CONCLUSIONS

We hope that the effort to thoroughly measure SB and ER using gold standard methods and cutting-edge technology will advance the knowledge of SB. The findings of this study may contribute to a better understanding of the relationship among SB, ER, affect, and sleep disturbances. By identifying the role of ER in SB, the results may pave the way for the development of targeted interventions for SB management to alleviate the pain and distress of those affected.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/41719.

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.

Systematic Review on the Link between Sleep Bruxism and Systemic Chronic Inflammation

Sleep bruxism (SB) is a sleep-related behavior characterized as rhythmic (phasic) or non-rhythmic (tonic) masticatory muscle activity. SB is a common sleep behavior with a predominantly central origin. The aim of this systematic review was to evaluate the relationship between inflammatory status and SB according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (PRISMA 2020). The research was registered at PROSPERO (CRD42023395985). We performed a systematic literature analysis using five different databases. Furthermore, the backward snowballing technique was applied to identify additional papers. Initially, 28 papers were screened from the database search, and 162 papers were revealed in the backward snowballing process. Eventually, five articles were included. Data concerning the inflammatory status of patients experiencing SB were investigated and summarized. Due to the heterogeneity of the compared studies, only a qualitative comparison and narrative summary were performed. The results suggest that SB could be associated with systemic inflammation. In fact, this systematic review revealed that there are no papers conclusively showing that the inflammatory status in bruxers is comparable to non-bruxers. However, each of the examined studies utilized different methods of assessing systemic inflammation, which makes the results dubious.

Bruxism as a new Risk Factor of Musculo-Skeletal Disorders?

OBJECTIVES

Musculoskeletal disorders (MSDs), particularly neck and low back pain, constitute a major public health issue worldwide with a heavy morbidity and economic impact. However, the relationships between the stomatognathic system and MSDs are subjected to debate, data sorely lacking. The study objective was to investigate the association between bruxism (BR) and MSDs. Secondary objective includes the study of the association between tooth wear (TW) and MSDs.

METHODS

This is a cross-sectional study on 425 participants frequenting a university dental clinic. The presence of MSDs was evaluated with the standardized Nordic questionnaire. The sleep and awake BR assessments were based on clinical examination and self-report. TW was measured with the BEWE index. Socio-demographic factors, medical history, life habits and stress were analyzed as potential confounding variables.

RESULTS

91% of patients reported at least one MSD during the preceding 12 months and 78.8% were diagnosed as bruxers. In multivariate analyses, BR was associated with a 5-fold increased risk of prevalent MSD (OR=5.88 (2.7-12.5), p<0.0001). Regarding TW, for a one-point increase in anterior BEWE score, the risk to present an MSD was increased by 53% (OR=1.53 (1.12-2.08), p=0.0076). Moreover, BR was independently associated with neck, shoulder, upper back, low back, hip & thigh and knee MSDs. Anterior TW was independently associated with neck, low back and hip & thigh MSDs, and global TW with knee MSDs.

CONCLUSIONS

BR and TW were shown to be associated with MSDs. The cause-and-effect relationships between those factors needs to be analyzed to optimize prevention and therapeutic care.

CLINICAL SIGNIFICANCE

Results suggest that the body is a whole, a balanced muscular system, where every part constitutes a link of the chain. MSDs management and prevention may require a multidisciplinary team approach and future perspectives include defining the dentist's role in this context, particularly with respect to BR diagnostic and treatment.

Prevalence of Possible Sleep Bruxism and Its Association with Social and Orofacial Factors in Preschool Population

The prevalence of bruxism in the preschool population varies according to different investigations. The aim of this study was to investigate the prevalence of sleep bruxism and its relationship with social and orofacial factors in children aged 3 to 5 years. Three hundred forty-three preschool children were divided into two groups, one with nocturnal bruxism, as reported by parents, and another without this disorder. Questionnaires were distributed to the parents to determine the children's family social status and parafunctional habits at the time of the study. The clinical inspection confirmed the presence of certain parafunctional habits and the children's occlusal characteristics. The data obtained were analysed using descriptive statistics such as frequency chi-square tests to identify the influence of qualitative variables. Of the total sample, 28.9% of preschoolers presented sleep bruxism. The highest prevalence was observed in boys (61.6%) at the age of 5 years (41.4%). Characteristics associated with this pathology were lip incompetence, open bite, crossbite, and overbite, with p < 0.05. Sleep bruxism in preschool children has a higher prevalence in boys and is more frequently expressed from 5 years of age. Open bite, overbite, and crossbite should be considered factors associated with parafunction.

A systematic review

Objectives

The present paper aims to systematically review the literature published from 2015 to 2023 on bruxism in children with the aim to compilate the best available evidence.

Materials and Methods

A systematic search in the National Library of Medicine's PubMed, Medline (EBSCO), SCOPUS, and Google Scholar databases was performed to identify all studies on humans assessing genetic, biopsychosocial, and sleep factors assessed with any different approach for sleep bruxism (SB) in children and its interventions. The selected articles were assessed independently by the two authors according to a structured reading of the article's format (PICO). The quality of the articles was evaluated using Quality Assessments Tool for Experimental Bruxism Studies (Qu-ATEBS) and the JBI critical appraisal tools.

Results

A total of 16 articles were included for discussion in the review and grouped into questionnaire/parental-report (n = 7), SB assessment through parental report of SB and clinical examination (n = 4), and instrumental assessment (n = 5) studies. The total quality scores evaluated with STROBE and Qu-ATEBS were high for all included papers. However, in general, there was no control of bias strategies and there was no control group in the intervention studies.

Conclusions

Investigations based on self-report, clinical, and instrumental bruxism assessment showed a positive association with genetics, quality of life aspects (school and emotional functions and overuse of screen-time), mother anxiety and family conformation, diet, alteration in sleep behaviors and architecture, and sleep breathing disorders. Additionally, the literature presents options to increase airway patency and, thus, reduce the occurrence of SB. Tooth wear was not found to be a major sign of SB in children. However, methods of SB assessment are heterogeneous and hamper a reliable comparison of the results.

Sleep Bruxism and Orofacial Pain in Patients with Sleep Disorders: A Controlled Cohort Study

BACKGROUND

The gold standard for the diagnosis of sleep bruxism (SB) is laboratory polysomnography (L-PSG) recording. However, many clinicians still define SB using patients' self-assessment and/or clinical tooth wear (TW). The purpose of this cross-sectional controlled study was to compare the prevalence of TW, head-neck muscles sensitivity and Temporomandibular Disorders (TMD) between SB and non-SB patients diagnosed with L-PSG in a cohort of patient with sleep disorders (SD).

METHODS

102 adult subjects with suspected SD underwent L-PSG recording to assess the presence of sleep disorder and SB. TW was clinically analyzed using TWES 2.0. The pressure pain threshold (PPT) of masticatory muscles were assessed using a Fisher algometer. Diagnostic criteria for TMD (DC/TMD) were used to evaluate the presence of TMD. SB self-assessment questionnaires were administered. TWES score, PPT, TMD prevalence and questionnaire results were compared between SB and non-SB patients.

RESULTS

22 SB patients and 66 non-SB patients with SD were included. No significant differences emerged between groups in regards to TW, the PPT values, or SB's self-assessment questionnaires as well the prevalence of TMD.

CONCLUSION

in a SD population, TW is not pathognomonic of active SB and SB self-assessment is not reliable. There seems to be no correlation between SB, TMD and head/neck muscle sensitivity.

Diagnostic accuracy of a portable device (Bruxoff®) to measure sleep bruxism

BACKGROUND

Diagnosis of sleep bruxism (SB) challenges clinicians every day due to multiple forms of assessment tools available, including self-reported questionnaires, clinical examinations, portable devices and laboratory polysomnography (PSG). PSG has become the gold standard for evaluating SB, but it can be limited due to cost and restricted accessibility which often is characterised by long waiting times. Hence, there is a need for the development of a reliable method that can assess SB in a simple and portable manner, which would offer acceptable sensitivity and specificity to evaluate SB.

OBJECTIVE

The objective of this study was to investigate reliability and validity of the Bruxoff® device for the diagnosis of SB compared to the PSG.

METHODS

Forty-nine subjects underwent one night of polysomnographic study with simultaneous recording with the Bruxoff® device. Rhythmic masticatory muscle activity (RMMA) index was scored according to published criteria. Pearson correlation, Bland-Altman plot and receiver operating characteristic (ROC) curve outcomes were used to quantify the agreement between both methods.

RESULTS

Receiver operating characteristic analysis showed an acceptable accuracy for the Bruxoff® with sensitivity of 83.3% and specificity of 72% when the cut-off was set at two events per hour. Pearson correlation analysis showed a nearly significant correlation between PSG and Bruxoff® for RMMA index (r = .282 p = .071) and for total SB episodes per night (r = .295 p = .058). Additionally, the Bland-Altman plot revealed a consistent and systematic difference in the measurement of events between devices.

CONCLUSION

The Bruxoff® device appears to be a promising diagnostic method for clinical use, but further study is needed.

Effect of occlusal equilibration on masticatory muscle activity in females with sleep bruxism: a double-blind randomised controlled trial

Masticatory muscle activity during sleep has been considered independent of variations in the structural characteristics of the dental occlusion. However, scientific evidence contradicting an occlusal causal role is missing. The purpose of this study was to test the null hypothesis that sleep bruxism (SB) is independent of the presence of occlusal interferences. A total of 17 healthy female subjects (mean [SD] age 24.9 [4.1] years) presenting with SB, and randomly divided into two groups, were evaluated after receiving either elimination of occlusal interferences (Test group) or elimination of sharp margins without change in occlusal contacts (Control group). Audio-video polysomnography (PSG) recordings were undertaken before and after treatment (mean [SD] duration 14.4 [3.8] months). Two subjects in each group (< 2 rhythmic masticatory muscle activity [RMMA]/h) were excluded for statistical analysis. During the total sleep time (TST), the Test group exhibited a higher reduction in frequency of episodes per hour than the Control group (p < 0.05). The reduction in duration of episodes was also higher in the Test group during the TST. The Test group presented an increase in sleep stage N3 (p < 0.05) at the final PSG when compared with the initial PSG, and a higher percentage of N3 (p < 0.05) at the final PSG when compared to the Control group. Elimination of occlusal interferences resulted in a significant reduction of masseter and temporal muscle activity during sleep in females presenting with SB. Based on these results, the null hypothesis is rejected. The hypothesis of occlusal interferences as a risk factor for SB is still patent.

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.

The effects of mandibular advancement appliance therapy on jaw-closing muscle activity time-related to oxygen desaturations: A randomised controlled trial

BACKGROUND

Previous study showed that in individuals with obstructive sleep apnea (OSA), the contractions of masseter muscles after respiratory events can be nonspecific motor phenomena, dependent on the duration of respiratory arousals rather than the occurrence of the respiratory events. However, the role of intermittent hypoxia in the occurrence of jaw-closing muscle activities (JCMAs) was not taken into consideration. An exposure to intermittent hypoxia has been shown to initiate a series of activities, including muscular sympathetic activity in patients with OSA.

OBJECTIVE

To determine the effects of mandibular advancement appliance (MAA) therapy on JCMA time-related to oxygen desaturation with and without arousal in individuals with OSA.

METHODS

Eighteen individuals with OSA (age: 49.4 ± 9.8 years, apnea-hypopnea index (AHI): 10.0|18.4|30.3, JCMA index: 1.7|4.3|5.6), participated in a randomised controlled crossover clinical trial, in which two ambulatory polysomnographic recordings were performed: one with MAA in situ and the other without MAA in situ. JCMAs were recorded bilaterally from both masseter and temporalis muscles.

RESULTS

There was no significant effect of the MAA on the overall JCMA index (Z = -1.372, p = .170). With the MAA in situ, JCMA index time-related to oxygen desaturation with arousal significantly decreased (Z = -2.657, p = .008), while there was no significant effect of the MAA on the JCMA index time-related to oxygen desaturation without arousal (Z = -0.680, p = .496).

CONCLUSION

Effective mandibular advancement appliance therapy significantly reduces jaw-closing muscle activities time-related to oxygen desaturation with arousal in individuals with OSA.

Three-dimensional evaluation of sleep bruxism-related splint wear using a dental laboratory scanner: A preliminary clinical study

BACKGROUND

The wear depth on the occlusal splint (OS) is reportedly associated with the sleep bruxism (SB) level, as evaluated using portable polysomnography (PSG) recordings. However, the OS is deformed owing to SB forces, possibly preventing the accurate quantification of the wear facets.

OBJECTIVES

We aimed to introduce a newly developed system to quantify the wear facets on the OS using a dental laboratory scanner (D810) and investigate the association between the wear facets, as evaluated with this system, and the SB level.

METHODS

Ten healthy individuals who were diagnosed with SB based on portable PSG recordings participated in this study. They were asked to wear the OS for 2 months. The first day after a 2-week adaptation period was defined as the reference day, and sequential scanning of the OS surface was performed on days 15, 30, and 45. Changes in the OS surface from the reference day allowed dimensional evaluation of the wear facets in terms of maximum wear depth, wear area, and wear volume. Multiple regression analyses were conducted to test whether each of these variables could be predicted by any of the SB-related variables.

RESULTS

The total duration of SB episodes per hour of sleep and the maximum muscle activity were significantly associated with the wear area, as measured with our system (adjusted R-squared was .78, p < .01).

CONCLUSION

Our system allows dimensional analysis of the wear facets on the OS surface in association with the SB level.

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.

Associations between snoring and dental sleep conditions: A systematic review

BACKGROUND

It is important for dentists to know if the presence of snoring is associated with the presence of other dental sleep conditions (e.g. obstructive sleep apnea [OSA], sleep bruxism [SB], gastroesophageal reflux disease [GERD], xerostomia and oro-facial pain). If so, dentists could play a significant role in the early recognition and management of these conditions.

OBJECTIVES

This systematic review aimed to: (i) investigate the associations between the presence of snoring and the presence of other dental sleep conditions; and (ii) determine if it is clinically relevant that dentists assess snoring in their population.

METHODS

The literature search was performed in PubMed and Embase.com in collaboration with a medical librarian. Studies were eligible if they employed regression models to assess whether snoring was associated with other dental sleep conditions, and/or investigated the incidence of snoring in patients with other dental sleep conditions and vice versa.

RESULTS

Of the 5299 retrieved references, 36 eligible studies were included. The available evidence indicates that the presence of snoring is associated with higher probabilities of OSA, GERD and headache. Due to limited evidence and conflicting findings, the currently available articles are not indicative of associations between the presence of snoring and the presence of SB and oral dryness.

CONCLUSION

Within the limitations of this study, it can be concluded that the presence of snoring is associated with higher probabilities of OSA, GERD and headache. Therefore, it is clinically relevant that dentists assess snoring in their patient population.

Sleep Apnea-Hypopnea Syndrome and Sleep Bruxism: A Systematic Review

The aim of this study was o determine the relationship between sleep bruxism (SB) and sleep apnea-hypopnea syndrome (SAHS) at the pathophysiological level, the risk factors, as well as the common signs and symptoms. A search was carried out using the databases PubMed, Web of Science, Scopus, and the Cochrane Library together with the Boolean equation "bruxism" AND "sleep apnea" AND "relation*"; the systematic search strategy limited the results to English language articles published from 2013 until December 2021. This review was conducted in accordance with the PRISMA statement. Nine articles were reviewed to relate SAHS and SB at different levels: two were systematic reviews (22%) and seven were research studies (78%). According to the literature reviewed, SB and SAHS occur simultaneously in 21.0% to 41.3% of cases. There are signs and symptoms that are common to both SAHS and SB. Rhythmic masticatory muscle activity (RMMA) precedes an SAHS event in 25% of subjects with SB, in contrast to 55% of the general population. SB and SAHS seem to have a certain concomitance, ranging between 20% and 40%, and they also share some risk factors such as advanced age, obesity, smoking, and alcohol consumption. Dentists should be aware of this relationship, as part of a multidisciplinary team, for early diagnosis.

Wear Management of Colored Foils for the Assessment of Sleep Bruxism Patterns-A Prospective, Randomized Crossover Study

The assessment of bruxism relies on clinical examinations, questionnaires, and polysomnography. The additional use of colored foils (BruxChecker^®) could enable a more precise evaluation of bruxing patterns. To assess differences between use of the foils during stress periods or just on consecutive nights and to determine a reasonable duration of using the foils, 28 patients were classified according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and were randomly assigned to wearing the 12 foils for six consecutive nights (alternately in the upper and lower jaw; "consecutive") or six nights within one month following days of high stress ("stress") in a crossover design. The sizes of the attrition areas were measured with ImageJ. Stress was evaluated using the Perceived Stress Scale. The Stress Coping Questionnaire (SVF-120) was used for assessing habitual stress coping strategies. Areas of attrition increased significantly from day 1/2 to 5/6, both for the upper and lower jaw. Molars in the mandible had significantly larger attrition areas than in the maxilla. No significant differences were detected between "consecutive" and "stress" phases. The foils were suitable for differentiating teeth more or less affected by bruxism and were able to show that areas of attrition increased with days, indicating that some adaptation takes place and several days of wearing the foils are required to show the full picture. However, no differences between low/moderate- and high-stress phases were detected.

Relationships between respiratory and oromotor events differ between motor phenotypes in patients with obstructive sleep apnea

Purpose

The present study investigated the relationship between sleep bruxism (SB) and obstructive sleep apnea (OSA) in relation to the sleep architecture.

Methods

We conducted a cross-sectional study. Polysomnographic recordings were performed on 36 patients. Sleep, respiratory, and oromotor variables, such as rhythmic masticatory muscle activity (RMMA) and non-specific masticatory muscle activity (NSMA), were compared between OSA patients with or without SB. A correlation analysis of the frequency of respiratory and oromotor events in NREM and REM sleep was performed. The frequency of oromotor events following respiratory events was also assessed.

Results

The proportion of REM sleep was higher in OSA patients with SB than in those without SB (p = 0.02). The apnea-hypopnea index (AHI) did not significantly differ between the two groups; however, AHI was approximately 8-fold lower during REM sleep in OSA patients with SB (p = 0.01) and the arousal threshold was also lower (p = 0.04). Although the RMMA index was higher in OSA patients with than in those without SB (p < 0.01), the NSMA index did not significantly differ. The percentage of RMMA following respiratory events was significantly higher in OSA patients with than in those without SB, whereas that of NSMA did not significantly differ. The frequency of oromotor events throughout the whole night positively correlated with AHI. However, regardless of the sleep state, AHI did not correlate with the RMMA index, but positively correlated with the NSMA index.

Conclusion

In consideration of the limitations of the present study, the results obtained indicate that OSA patients with SB have a unique phenotype of OSA and also emphasize the distinct relationship of respiratory events with RMMA and NSMA.