Understanding the clinical management of co-occurring sleep-related bruxism and obstructive sleep apnea in adults: A narrative and critical review

Sleep-related bruxism (SRB) is a motor oral behavior characterized by tooth grinding and jaw clenching activity, reported by 8%-12% of the adult general population and 3% of older individuals. The frequency of one of its biomarkers, rhythmic masticatory muscle activity (RMMA), remains elevated across ages. Obstructive sleep apnea (OSA) is associated with the brief and repetitive pause of breathing (apnea) and with transient reduction in oxygen (hypoxia). OSA is observed at all ages and in about 50% of older individuals with a male preponderance. SRB clinical assessment is based on self-reporting of tooth grinding sound, awareness of clenching, jaw pain or headache, and clinical observation of tooth damage. OSA clinical assessment is based on sleepiness and fatigue, snoring, sleep quality, and awareness of breathing cessation, plus clinical examination of anatomical factors (e.g., obesity, retrognathia, large tonsil, macroglossia), age, gender, and body mass. Although the literature does not support association or causality between these two conditions, the co-occurrence is reported in about 30%-50% of adults. To confirm a diagnosis of co-occurring SRB and OSA, home sleep testing (HST) may be indicated. A sleep test is performed using electromyography (EMG) of jaw muscle (masseter or temporalis) and cardio-respiratory variables (e.g., air flow, respiratory effort, oxygen level, heart rate). The management of co-occurring SRB and OSA for individuals with prosthodontic needs is challenging to prevent compromising the oro-pharyngeal space and breathing efficiency. OSA treatment in the presence of SRB includes continuous positive airway pressure (CPAP) use alone or with an occlusal splint or mandibular advancement device (MAD). In addition, the following may be considered: supine sleep correction device, myofuncional therapy, medications, and surgeries. All have limitations and risks. Individual variability suggests that phenotyping is mandatory to select the most efficient and personalized treatment.

Association between the severity of possible sleep bruxism and possible awake bruxism and attrition tooth wear facets in children and adolescents

OBJECTIVE

To evaluate the association between the severity of possible sleep bruxism (PSB) and possible awake bruxism (PAB) and attrition tooth wear facets (ATWF) in children/adolescents.

METHODS

Four hundred-thirty-four children/adolescents enrolled in schools in Lavras, Brazil, participated in this cross-sectional study. Caregivers answered a questionnaire about their childrens' PSB. Children/adolescents answered a questionnaire about the occurrence of PAB.

RESULTS

ATWF among individuals without PSB and PAB was lower than those with moderate/severe PSB (p = 0.038) and moderate/severe PAB (p = 0.003). ATWF in anterior teeth was lower among individuals without PSB compared to those with mild (p = 0.015) and moderate/severe PSB (p = 0.032). ATWF in posterior teeth was lower among individuals without PAB compared to those with mild (p = 0.046) and moderate/severe PAB (p = 0.017).

CONCLUSION

The number of attrition tooth wear facets is proportional to the severity of PSB and PAB.

Multimodal transcutaneous auricular vagus nerve stimulation: An option in the treatment of sleep bruxism in a "polyvagal" context

OBJECTIVE

To consider the possible role of the vagus nerve (VN) in the pathophysiology of sleep bruxism (SB) and introduce a multimodal protocol of transcutaneous auricular stimulation of the VN in the treatment of SB patients.

METHODS

Ten patients with SB underwent four sessions of electric transcutaneous auricular vagus nerve stimulation (ta-VNS) in specific auricular areas. The patients were advised to manually stimulate the same areas between sessions. Masticatory muscle activity and sleep parameters were measured by a polysomnography (PSG) before and after the treatment. Heart rate variability (HRV) parameters were measured during each stimulation.

RESULTS

PSG analysis revealed a statistically significant reduction in tonic SB index and tonic contraction time. HRV parameters showed a statistically significant increase in mean values of the vagal tone after each session of stimulation. No side effect was reported.

CONCLUSION

The stimulation of the VN might have a role in the treatment of SB.

Sleep-related bruxism, microarousals and oxyhaemoglobin desaturations in sleep stages: A cross-sectional study in a large apnoeic population

BACKGROUND

Sleep-related bruxism (SB) is the habit of grinding or clenching the teeth during sleep, mediated by the non-peripheral central nervous system.

PURPOSE

The objectives of this cross-sectional study were to evaluate associations between SB, microarousals and oxyhaemoglobin desaturations and to compare the frequency of SB and microarousals in sleep stages, in an apnoeic population.

METHODS

Two hundred and forty individuals composed the sample, who underwent a single full-night polysomnography. Self-reports and clinical inspections were not considered for assessing SB. The polysomnographic assessment of SB was performed using electrodes placed on masseter muscles and chin. SB was defined as more than two events of rhythmic masticatory muscle activity per hour of sleep. Microarousals were considered when there were abrupt changes in electroencephalogram frequencies, without complete awakening, lasting from 3 to 15 s. Oxyhaemoglobin desaturations were defined as significant drops (≥3%) in basal oxygen saturations. With these data, SB, microarousals and oxyhaemoglobin desaturations were evaluated and submitted to statistical analysis.

RESULTS

Statistically significant differences were observed between bruxers and non-bruxers when comparing the rates of microarousals (p < .001) and oxyhaemoglobin desaturations (p = .038). There was a higher number of SB and microarousals in NREM (non-rapid eye movement) two sleep stage (p < 0.001). Bruxers had a greater risk of higher numbers of microarousals (OR = 1.023; p = .003), which did not occur for oxyhaemoglobin desaturations (OR = 0.998; p = .741).

CONCLUSIONS

A higher number of microarousals presents relationship with SB; associations between SB and oxyhaemoglobin desaturations remained inconclusive; higher frequency of SB and microarousals was observed in NREM 2 sleep stage.

Erectile dysfunction and sleep related bruxism: An exploratory review of an improbable association

The World Health Organization recognizes sexual health as not merely the absence of disease, but a state of physical, mental, and social well-being in relation to one's sexuality. Achieving sexual satisfaction is pivotal for many individuals, as it significantly contributes to their quality of life. Among various sexual disorders, erectile dysfunction (ED) is notably prevalent, affecting an estimated 10-20 million men in the United States alone. This condition impacts not just the person experiencing it but also significantly influences their intimate connections with partners. Although the causes of ED are multifactorial, recent research highlights a compelling association between sleep disorders, such as sleep deprivation, obstructive sleep apnea (OSA), and insomnia, and the incidence of ED. Furthermore, engaging in night work has been observed to exacerbate the risk of developing ED. One common sleep disorder, sleep related bruxism (SRB), despite its prevalence, has not generally been associated with ED. However, there is some interesting evidence hinting at a potential relationship, including a few studies reporting a high prevalence of ED in individuals with SRB. This review delves into the epidemiological, etiological, and mechanistic links between ED and SRB, aiming to uncover potential intersections between these two conditions. These insights could pave the way for innovative research avenues, possibly exploring treatments like vasodilation medication, that might concurrently address both ED and SRB.

Prevalence, awareness, and management of bruxism in Thai dental students: A cross-sectional study

OBJECTIVE

To determine the prevalence of self-reported bruxism, awareness of bruxism's adverse effects, and bruxism management among Thai undergraduate dental students.

METHODS

An online self-reported questionnaire was designed and tested for validity and reliability and then distributed to dental students at 12 universities in Thailand from September 2020 to January 2021.

RESULTS

There were 464 respondents (338 females and 126 males) with an average age of 21.42 ± 2.06 years. The prevalence of self-reported awake and sleep bruxism was 35.78% and 37.28%, respectively, and 19.40% had both awake and sleep bruxism. Awareness scores were higher for dentists than for patients (p< 0.001). Only 12.14% of sleep bruxers still wear an occlusal splint for bruxism management.

CONCLUSION

The prevalence of self-reported awake and sleep bruxism was high among Thai dental students. They are well aware of the adverse effects of bruxism with inappropriate management of the condition.

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.

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.

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 ± standard deviation = 42.8 ± 12.2 years; mean body mass index ± standard deviation = 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 (SB when rhythmic masticatory muscle activity ≥ 2 episodes/h). Logistic regression was performed, with SB as the dependent variable and with age, sex, body mass index, 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 (odds ratio = 0.965 [0.944, 0.987]) and shorter total sleep time (odds ratio = 0.760 [0.609, 0.948]) significantly increased the risk of SB (P < .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: onderzoekmetmensen.nl; Name: A Large Sample Polysomnographic Study on Sleep Bruxism; URL: https://trialsearch.who.int/Trial2.aspx?TrialID=NL-OMON19947; Identifier: NL8516.

CITATION

Li D, Lobbezoo F, Hilgevoord AAJ, de Vries N, Aarab G. Prevalence and risk factors of sleep bruxism in adults with primary snoring: a large-scale polysomnographic study. J Clin Sleep Med. 2024;20(8):1331-1337.

Prevalence and predictors of sleep bruxism in patients with obstructive sleep apnea and the effect of positive airway pressure treatment

BACKGROUND

Sleep bruxism (SB) is often found to co-exist with obstructive sleep apnea (OSA). However, there are no data on prevalence and risk factors of SB in patients with OSA patients regarding the effect of optimal positive airway pressure (PAP).

OBJECTIVE

This study aimed to study prevalence and risk factors of SB in OSA and to compare SB episodes during pre-treatment versus during optimal PAP therapy.

METHODS

This investigation was a retrospective study including randomly selected patients with OSA who underwent split-night polysomnography. Data were collected from August 2021 to October 2022. Clinical demographic data and SB data were analyzed. The association between SB episodes and obstructive respiratory events were manually reviewed. If most of the SB episodes were observed within 5 s following obstructive respiratory events, SB was defined as SB associated with OSA. Comparison of SB index (SBI) was made between baseline portion of the study versus during optimal PAP.

RESULTS

Among 100 patients enrolled, mean age was 50.8 ± 16.7 years and 73 subject (73%) were male. Mean respiratory disturbance index (RDI) and mean nadir oxygen saturation were 52.4 ± 33.4 and 79.3 ± 11.2% respectively. During the baseline portion of the study, 49 patients (49%) had SB and 31 patients (31%) had severe SB (SBI ≥ 4). Sleep bruxism associated with OSA was observed in 73.5% of all SB. The risk factor for SB was endorsement of nocturnal tooth grinding (odds ratio (OR) 5.69, 95%CI 1.74-18.58). Risk factors for severe bruxism were male sex (OR 4.01, 95%CI 1.02-15.88) and endorsement of nocturnal tooth grinding (OR 9.63, 95%CI 2.54-36.42). Risk factors for SB associated with OSA were non-supine RDI (OR 1.02, 95%CI 1.001-1.034) and endorsement of nocturnal tooth grinding (OR 5.4, 95%CI 1.22-23.93). In SB group, when comparison was made between baseline portion and during optimal PAP, significant reduction of SBI was observed (5.5 (3.2, 9.3) vs. 0 (0, 2.1), p < 0.001). Median difference of SBI between baseline portion and during optimal PAP was 4.4 (2.0, 8.3) (p < 0.001).

CONCLUSIONS

In this group of patients with OSA, almost half was observed to have SB in which the majority were associated with OSA. Optimal PAP resulted in a significant reduction in SB episodes. In addition to endorsement of nocturnal tooth grinding, non-supine RDI was observed to be a potential risk factor for SB associated with OSA.

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.

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.

Effects on Sleep Bruxism Activity of Three Different Oral Appliances: One Year Longitudinal Cohort Study

BACKGROUND

Different oral appliances (OAs) have been proposed to control sleep bruxism (SB) detrimental effects on the stomatognathic system.

OBJECTIVE

The aim of the study was to evaluate the effect of different OAs on SB activity and masticatory muscle activity (sMMA) measured by EMG.

METHODS

This longitudinal cohort study was conducted on 51 patients (21 M, 30 F, mean age 26,5 ± 3,5) suffering from SB diagnosed with a validated portable EMG-ECG holter and wearing different OAs: occlusal splints, functional appliance with metallic bites and clear aligners followed after 1 week, 1 month, 3 months, 6 months and 12 months from delivery. A control group of 16 non-treated SB patients (6 M, 10 F mean age 27,1 ± 1,4) was used as a reference. A multiple regression analysis was performed to estimate the differences between groups. The level of significance was set as P value <0,05.

RESULTS

Occlusal splint reduced sleep bruxism index after 1 week, 3, 6 and 12 months from delivery while functional appliance only after 12 months. Occlusal splints reduced general phasic contractions only in the first week and sleep bruxism-related phasic contractions at 1 week, 3 and 6 months after delivery with no significant reductions after 12 months. Patients wearing clear aligners showed a reduction in general tonic contractions after 6 and 12 months.

CONCLUSION

Resin and metal bites can reduce sleep bruxism index, while resin bites can reduce sleep bruxism-related phasic contractions. Clear aligners do not influence sleep bruxism index but can reduce tonic contractions.

Bruxism and oro-facial pain not related to temporomandibular disorder conditions: Comorbidities or risk factors?

INTRODUCTION

Bruxism has historically been of particular interest to the field of dentistry, primarily due to the inferred damage it may cause to the dentition and supporting periodontal structures. The definition of bruxism itself has undergone multiple changes over time. In addition, the effects of bruxism as it relates to oro-facial pain conditions has remained a debatable topic.

PURPOSE

To review the available literature relating to bruxism and non-temporomandibular disorder (TMD) pain conditions.

METHODS

A literature search was conducted with the assistance of an expert librarian. The following databases were reviewed: PubMed, MEDLINE, EMBASE and Google Scholar. For additional references, articles were also retrieved by hand search from the selected papers. Any articles that were not published in English, or the focus were related to temporomandibular disorders were excluded.

CONCLUSIONS

While bruxism and certain headache conditions do tend to occur together frequently, evidence relating to any clear common pathophysiological mechanism has yet to be fully elucidated. Robust evidence as it relates to the relationship between bruxism and other non-TMD oro-facial pains is also lacking.

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.

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.

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.

Oral appliances reduce masticatory muscle activity-sleep bruxism metrics independently of changes in heart rate variability

OBJECTIVES

Sleep bruxism (SB) is associated with physiological activities including sympathetic autonomic system dominance and sleep micro-arousal. While oral appliances (OA) are used to prevent SB harmful effects, the influence of OAs physiological mechanisms during sleep is unknown. The aim of this study is to assess whether heart rate variability (HRV) changes, as a marker of autonomic nervous system activity, would be associated with the OA mechanism of action on SB using occlusal splint (OS) and mandibular advancement splint (MAS).

MATERIALS AND METHODS

A retrospective analysis, from data previously collected in 21 participants with SB (25.6 ± 4.5 years) with polysomnographic recordings, was done. HRV data were compared between a reference night (no-device) and ones during which OS or MAS was used in a crossover study design. Rhythmic masticatory muscle activity (RMMA) index was compared between nights. HRV was evaluated using autoregressive model analysis for three sections: baseline (distance from RMMA), immediately before, and after RMMA period.

RESULTS

A significant reduction in RMMA index, when wearing OA during sleep, was observed (P < 0.01), but was not associated with HRV parameters change. HRV significantly changed after RMMA onset for nights with OA during non-REM sleep in comparison with baseline (P < 0.02).

CONCLUSIONS

The usage of OAs for SB participants reduced RMMA, but most likely independently of changes in HRV linked to the mechanism associated with SB genesis.

CLINICAL RELEVANCE

Wearing OA seems to reduce grinding noise and protect from dental injuries but does not seem to influence SB genesis.

Accuracy of sleep bruxism scoring based on electromyography traces of different jaw muscles in individuals with obstructive sleep apnea

STUDY OBJECTIVES

Sleep bruxism is characterized by rhythmic masticatory muscle activity (RMMA). This study aimed to determine the number and type of jaw muscles needed for a valid RMMA scoring in individuals with obstructive sleep apnea (OSA).

METHODS

10 individuals with OSA (4 males; age = 50.1 ± 8.1 years) were included in this study. RMMA was scored using one or more of the following jaw muscles' electromyography (EMG) traces of polysomnography recordings: bilateral masseter and temporalis (4MT; the reference standard), unilateral masseter (1M), bilateral masseter (2M), unilateral temporalis (1T), bilateral temporalis (2T), unilateral chin EMG (1C), and bilateral chin EMG (2C).

RESULTS

1M, 2M, 1T, and 2T showed excellent agreement with 4MT (intraclass correlation coefficient [ICC] = 0.751, 0.976, 0.815, and 0.950, respectively), while 1C and 2C presented fair agreement (ICC= 0.662 and 0.657). Besides, 2M and 2T displayed good sensitivity (87.8% and 72.0%) and positive predictive value (PPV; 83.1% and 76.0%). In contrast, 1M and 1T had good sensitivity (88.4% and 87.8%) but fair PPV (60.1% and 53.2%). 1C and 2C showed poor sensitivity (41.1% and 40.3%) and fair PPV (62.9% and 60.6%).

CONCLUSIONS

Polysomnography with bilateral masseter or temporalis muscle EMG traces is regarded valid in RMMA scoring in individuals with OSA. In contrast, unilateral masseter or temporalis muscle EMG showed only fair accuracy, and chin EMG had poor accuracy. Consequently, these montages cannot be recommended for RMMA scoring in the presence of OSA.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: The Effects of Oral Appliance Therapy on Masseter Muscle Activity in Obstructive Sleep Apnea; Identifier: NCT02011425.

Correlation between Bruxism and Gastroesophageal Reflux Disorder and Their Effects on Tooth Wear. A Systematic Review

Bruxism and gastroesophageal reflux (GERD) can lead to wear of the dental tissues. Wear has a mechanical or chemical origin, and it is of extrinsic or intrinsic type. Bruxism and GERD are two etiological factors of dental wear. The intrinsic mechanical wear (abfraction) of Bruxism and intrinsic chemical wear (erosion) of GERD are both involved in sleep disorders; indeed, they could have associations and act in synergy in dental wear. The purpose of this review was to find out the possible associations between bruxism and GERD and their effects on tooth wear. The research was conducted on PubMed and the Cochrane Library using the following Keywords/Mesh Terms: Tooth wear, Bruxism, Sleep Bruxism, Sleep Disorders, or GERD. Only systematic reviews and clinical studies performed exclusively on human subjects were included in the review. Initially, the research gave more than 630 results on dental wear, bruxism and GERD and after application of the inclusion criteria irrelevant studies were excluded, and 5 studies were finally included in this review. It was possible to observe the presence of some associations between the two problems (reflux and GERD) and hypothesize negative effects on tooth wear. This research revealed the presence of an interconnection between these three problems (reflux, GERD and tooth wear) that can further act in synergy by attacking the hard dental tissues both from a chemical (reflux) and mechanical (bruxism) point of view. The dentist could play a role of “sentinel” in a multidisciplinary team, intercepting these problems early in order to treat them in the most appropriate way. PROSPERO Registration Number: CRD42021234209.

The Parasomnias and Sleep Related Movement Disorders—A Look Back at Six Decades of Scientific Studies

The objective of this article is to provide a comprehensive personal survey of all the major parasomnias with coverage of their clinical presentation, investigation, physiopathogenesis and treatment. These include the four major members of the slow-wave sleep arousal parasomnias which are enuresis nocturna (bedwetting), somnambulism (sleepwalking), sleep terrors (pavor nocturnus in children, incubus attacks in adults) and confusional arousals (sleep drunkenness). Other parasomnias covered are sleep-related aggression, hypnagogic and hypnopompic terrifying hallucinations, REM sleep terrifying dreams, nocturnal anxiety attacks, sleep paralysis, sleep talking (somniloquy), sexsomnia, REM sleep behavior disorder (RBD), nocturnal paroxysmal dystonia, sleep starts (hypnic jerks), jactatio capitis nocturna (head and total body rocking), periodic limb movement disorder (PLMs), hypnagogic foot tremor, restless leg syndrome (Ekbom syndrome), exploding head syndrome, excessive fragmentary myoclonus, nocturnal cramps, and sleep-related epileptic seizures. There is interest in the possibility of relationships between sleep/wake states and creativity.

A Novel Quantitative Method for Tooth Grinding Surface Assessment Using 3D Scanning

Sleep bruxism is an oral parafunction that involves involuntary tooth grinding and clenching. Splints with a colored layer that gets removed during tooth grinding are a common tool for the initial diagnosis of sleep bruxism. Currently, such splints are either assessed qualitatively or using 2D photographs, leading to a non-neglectable error due to the 3D nature of the dentition. In this study we propose a new and fast method for the quantitative assessment of tooth grinding surfaces using 3D scanning and mesh processing. We assessed our diagnostic method by producing 18 standardized splints with 8 grinding surfaces each, giving us a total of 144 surfaces. Moreover, each splint was scanned and analyzed five times. The accuracy and repeatability of our method was assessed by computing the intraclass correlation coefficient (ICC) as well reporting means and standard deviations of surface measurements for intra- and intersplint measurements. An ICC of 0.998 was computed as well as a maximum standard deviation of 0.63 mm2 for repeated measures, suggesting an appropriate accuracy of our proposed method. Overall, this study proposes an innovative, fast and cost effective method to support the initial diagnosis of sleep bruxism.

Temporomandibular disorders in patients with polysomnographic diagnosis of sleep bruxism: a case-control study

BACKGROUND

Temporomandibular disorders (TMD) is a collective term that refers to complaints of temporomandibular joint (TMJ) pain, fatigue and/or pain of the craniocervical muscles, limitation of movement of the mandible, and TMJ noises. Sleep bruxism (SB) is a disorder involving rhythmic (phasic) or non-rhythmic (tonic) masticatory muscle activity during sleep and is not a movement disorder or a sleep disorder in otherwise healthy individuals. The present study aimed to support or reject the null hypothesis that there is no association between SB and TMD.

METHODS

The study population was recruited from patients who visited the Artmedica Clinic, Mossoro city, Rio Grande do Norte, Brazil. Patients who underwent polysomnography received information about the research and were invited to participate following the inclusion and exclusion criteria. The study sample consisted of 40 individuals with age ranging from 19 to 76 years. The subjects were administered the questionnaire of the European Academy of Craniomandibular Disorders (AEDC). Those who answered affirmatively to at least one question of the questionnaire were recommended to visit the primary researcher's dental clinic for examination; those who met the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were evaluated, and their condition was classified into one or more subtypes of TMD. The subjects were divided into 4 groups according to the polysomnographic findings and the responses to the AEDC questionnaire. Of the 40 individuals who answered the AEDC questionnaire and underwent polysomnography, 28 presented with TMD symptoms. The data were expressed as simple frequency and percentage values using statistical software. Values of p < 0.05 were considered to be significant.

RESULTS

The results showed that the frequency of TMD in individuals diagnosed to have SB was 46.4%. According to the DC/TMD of the 28 individuals, the most prevalent TMD subtype was local myalgia (85.7%). Of the total subjects, 32.5% had TMD and SB, 36.4% were males, and in the age range of 31 to 40 years (40%).

CONCLUSION

In this study sample, there was no association between SB as currently defined and TMD, thus confirming previous findings on this topic.

Cardiovascular Implications of Sleep Bruxism-A Systematic Review with Narrative Summary and Future Perspectives

Sleep bruxism is a common sleep-related behavior characterized as repetitive masticatory muscle activity. Genetic vulnerability to stress and anxiety is considered a basal component in the pathogenesis of bruxism events. Dysfunction of the autonomic nervous system related with an arousal during sleep is considered an underlying cause of the cardiovascular implications of sleep bruxism. Increased cardiovascular risk was previously linked with sleep conditions: for example, obstructive sleep apnea and insomnia, and sleep bruxism. The aim of present systematic review was to evaluate the current arguments on the relationship between sleep bruxism and cardiovascular diseases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We have reviewed the Embase, PubMed (Medline) and Scopus databases to identify applicable articles (1994-2021). A total of 127 records in English language were identified, then after screening and exclusion of nonrelevant records, 19 full-text articles were evaluated. Finally, we included 12 studies for synthesis. Due to the heterogeneity of the compared studies, only a qualitative comparison and narrative summary were performed. In the majority of studies, increased sympathetic activity was successfully established to escalate heart rate variability, the inflammatory process, oxidative stress, endothelial remodeling and hormonal disturbances, leading to hypertension and other cardiovascular complications.

Effect of Sleep Bruxism Intensity on Blood Pressure in Normotensives

The present research aimed to investigate the influence of sleep bruxism (SB) intensity on blood pressure parameters in normotensive subjects by using an ambulatory blood pressure device. The study group included 65 normotensive individuals suspected of having SB. All participants underwent one-night video-polysomnography, and ambulatory blood pressure monitoring was performed the next day; 86.15% of them were diagnosed with SB. Statistical analysis included correlation and regression analysis. The obtained results showed that systolic blood pressure variability during sleep significantly increased in individuals with BEI > 4 (bruxism episodes index; episodes/hour) compared to those with BEI ≤ 4 (8.81 ± 3.36 versus 10.57 ± 3.39, p = 0.05). Multivariable regression analysis showed that systolic blood pressure variability at nighttime was also associated with the following independent risk factors: higher apnea-to-bruxism index, male gender, BEI > 4 episodes/hour, body mass index (BMI) ≥ 25 kg/m², higher arousal index, and shorter total sleep time. In summary, sleep bruxism intensity was associated with increased systolic blood pressure variability during sleep. Coincidental apnea, male gender, severe sleep bruxism (SB intensity with BEI > 4/hour), excess weight and obesity, higher arousal index, and shorter sleep time seem to be the main determinants that influence blood pressure in normotensive sleep bruxers.

Research routes on improved sleep bruxism metrics: Toward a standardised approach

A recent report from the European Sleep Research Society's task force "Beyond AHI" discussed an issue that has been a long-term subject of debate - what are the best metrics for obstructive sleep apnoea (OSA) diagnosis and treatment outcome assessments? In a similar way, sleep bruxism (SB) metrics have also been a recurrent issue for >30 years and there is still uncertainty in dentistry regarding their optimisation and clinical relevance. SB can occur alone or with comorbidities such as OSA, gastroesophageal reflux disorder, insomnia, headache, orofacial pain, periodic limb movement, rapid eye movement behaviour disorder, and sleep epilepsy. Classically, the diagnosis of SB is based on the patient's dental and medical history and clinical manifestations; electromyography is used in research and for complex cases. The emergence of new technologies, such as sensors and artificial intelligence, has opened new opportunities. The main objective of the present review is to stimulate the creation of a collaborative taskforce on SB metrics. Several examples are available in sleep medicine. The development of more homogenised metrics could improve the accuracy and refinement of SB assessment, while moving forward toward a personalised approach. It is time to develop SB metrics that are relevant to clinical outcomes and benefit patients who suffer from one or more possible negative consequences of SB.

Artificial Intelligence Analysis of Mandibular Movements Enables Accurate Detection of Phasic Sleep Bruxism in OSA Patients: A Pilot Study

PURPOSE

Sleep bruxism (SBx) activity is classically identified by capturing masseter and/or temporalis masticatory muscles electromyographic activity (EMG-MMA) during in-laboratory polysomnography (PSG). We aimed to identify stereotypical mandibular jaw movements (MJM) in patients with SBx and to develop rhythmic masticatory muscles activities (RMMA) automatic detection using an artificial intelligence (AI) based approach.

PATIENTS AND METHODS

This was a prospective, observational study of 67 suspected obstructive sleep apnea (OSA) patients in whom PSG with masseter EMG was performed with simultaneous MJM recordings. The system used to collect MJM consisted of a small hardware device attached on the chin that communicates to a cloud-based infrastructure. An extreme gradient boosting (XGB) multiclass classifier was trained on 79,650 10-second epochs of MJM data from the 39 subjects with a history of SBx targeting 3 labels: RMMA episodes (n=1072), micro-arousals (n=1311), and MJM occurring at the breathing frequency (n=77,267).

RESULTS

Validated on unseen data from 28 patients, the model showed a very good epoch-by-epoch agreement (Kappa = 0.799) and balanced accuracy of 86.6% was found for the MJM events when using RMMA standards. The RMMA episodes were detected with a sensitivity of 84.3%. Class-wise receiver operating characteristic (ROC) curve analysis confirmed the well-balanced performance of the classifier for RMMA (ROC area under the curve: 0.98, 95% confidence interval [CI] 0.97-0.99). There was good agreement between the MJM analytic model and manual EMG signal scoring of RMMA (median bias -0.80 events/h, 95% CI -9.77 to 2.85).

CONCLUSION

SBx can be reliably identified, quantified, and characterized with MJM when subjected to automated analysis supported by AI technology.

Over-the-counter bite splints: A randomized controlled trial of compliance and efficacy

Background

Occlusal splints are often used to curb the impacts of sleep bruxism (SB) on the dentition, and over‐the‐counter (OCT) options are becoming increasingly popular. OTC splints are usually fabricated at home by patients, but not routinely evaluated by dental professionals. It is unclear how OCT splints compare with more traditional splints that receive dental oversight.

Objectives

The present randomized controlled study tested how an OTC splint compared with a gold standard bite splint in terms of patient compliance (primary outcome) and efficacy (secondary outcomes).

Methods

Sixty‐seven subjects were randomly assigned to receive either the OTC (SOVA, N = 35) splint or the gold standard “Michigan” bite splint (MI, N = 32), with 61 completing the study (SOVA, N = 30; MI, N = 31). OTC‐splint subjects were required to fabricate their splints to clinically acceptable standards. Both groups wore the splints nightly for four months. Compliance was measured via daily diary. Efficacy outcomes evaluated stability, retention, periodontal health, night‐time rhythmic masticatory muscle activity (RMMA), and material wear.

Results

OTC‐splint subjects had difficulty fabricating splints to clinically acceptable standards. The number of night‐time RMMA bursts was significantly greater for the OTC splint group. Compliance and all other efficacy measurements were not significantly different between‐groups.

Conclusions

The results support the potential use of OTC splints for curbing the impacts of SB. However, the results strongly suggest that dentists should be actively engaged in overseeing patients' use of self‐fabricated appliances. This clinical trial is registered at ClinicalTrials.gov, Identifier number NCT02340663.

Dental sleep medicine: Time to incorporate sleep apnoea education in the dental curriculum

Dental sleep medicine is a discipline that includes conditions such as sleep breathing disorders (eg snoring and sleep apnoea), sleep bruxism, orofacial pain and sleep-related complaints, and to some extent gastro-oesophageal reflux disorder and/or insomnia. Obstructive sleep apnoea (OSA) is a life-threatening condition that dentists need to identify and manage when indicated in order to increase patient well-being and to be taken in consideration in the dental curriculum. The main objective of this paper is to highlight the relevance of dental sleep medicine in the context of dental education, and to discuss potential educational content for integration in the dental curriculum with a focus on OSA, a condition that is not yet integrated in many dental training curricula around the world.

Effect of laterotrusive occlusal scheme on chewing duration, external intercostal muscular activity, heart rate, and oxygen saturation

Objective: To evaluate the effect of the laterotrusive occlusal scheme on chewing duration, external intercostal (EIC) electromyographic (EMG) activity, heart rate (HR), and oxygen saturation (OS) during different tasks in the upright seated position.Methods: Fifty young participants, 25 with canine guidance and 25 with group function, were included. Chewing duration, bilateral EIC EMG activity, HR, and OS were recorded during the following tasks: 1) chewing until swallowing threshold; 2) laterotrusive teeth grinding.Results: Chewing duration, bilateral EIC EMG activity, HR, and OS showed no significant differences between the two laterotrusive occlusal schemes during the tasks studied.Conclusion: These results suggest that chewing duration, EIC muscle activity, HR, and OS were not significantly influenced by the laterotrusive occlusal scheme. Therefore, when a modification of the laterotrusive occlusal scheme is needed during oral rehabilitation or orthodontic treatment, canine guidance or group function should not significantly change EMG activity of EIC muscles.

Adult obstructive sleep apnoea: Pathogenesis, importance, diagnosis and imaging

Obstructive sleep apnoea (OSA) is a serious worldwide health problem. Moderate-to-severe OSA has been found in up to 50% of men and 25% of women in the middle-aged population. It results in a fourfold increase in all causes of mortality. The prevalence of OSA is underestimated, partly due to absence of symptoms but also lack of knowledge amongst the population at large as well as sectors of the medical profession. Imaging, performed predominantly by clinicians and research scientists, has been integral to evaluating the anatomical basis of OSA. Increased nasal resistance and a narrowed and elongated oropharynx lead to increased collapsibility of the upper airway, predisposing to airway collapse and apnoea during sleep when there is reduction in tone of the pharyngeal dilator muscles. Unfortunately, a significantly narrowed upper airway is usually ignored by radiologists: it is not part of their reporting 'check-list'. The imaging findings in the upper airway that are strongly associated with OSA and its sequelae in various organ systems are discussed. Imaging can strongly suggest OSA; the diagnosis requires a polysomnogram for confirmation. Treatment of moderate-to-severe disease is primarily with positive airway pressure applied by a nasal or oral mask which splints the upper airway. Although highly effective, compliance is limited and other treatment modalities are increasingly being utilized.

[Obstructive Sleep disordered breathing, sleep bruxism and periodontal diseases]

Sleep disordered breathing (SDB) may be associated with sleep bruxism and periodontal diseases. Through a review of the current literature, this article aims to describe the characteristics of sleep bruxism and its relationship with SDB as well as the current evidence supporting an association between periodontal diseases and SDB. Sleep bruxism is characterized by muscle clenching and tooth grinding during sleep, typically during N2 sleep stage and in association with micro-arousals. The probability of observing sleep bruxism is almost 4 times higher in the presence of SDB, with a close temporal relationship between the episode of upper airway obstruction or oxygen desaturation and the episode of bruxism, which most often occurs in the 0-10 seconds following the obstruction. These findings support the hypothesis that sleep bruxism is triggered by SDB and may have a "protective" role being a muscular activity that helps restore the permeability of the upper airways. On the other hand, SDB have been linked to periodontal diseases. Periodontal diseases are inflammatory and dysbiotic disorders that can have a negative impact on oral health (leading to the destruction of the periodontium and tooth loss) and on general health. Recently, it has been observed that SDB patients have a 1.6 to 4-fold higher risk of having or developing severe periodontitis, suggesting that SDB may be a new risk factor for periodontal diseases. Dentists, who are part of the team of sleep medicine specialists, have a key role in the detection, prevention and treatment of SDB and their relationship with sleep bruxism and periodontal diseases.

Eye movements in relation to rhythmic masticatory muscle activities in patients with sleep bruxism

OBJECTIVES

To characterize eye movements during rhythmic masticatory muscle activities (RMMAs) in patients with sleep bruxism (SB).

METHODS

Polysomnographic (PSG) recordings were performed on SB patients and normal controls during sleep (n = 8 for each group) and wakefulness (n = 9 for each group). The eye movements associated with episodes of RMMAs/SB during sleep and jaw movements during wakefulness were analyzed.

RESULTS

During sleep, all episodes of RMMAs/SB in the SB patients and controls were associated with eye movements and most of the RMMAs/SB related slow eye movements (SB patients: 96.29%, 1583/1644; Controls: 97.49%, 543/557) were horizontal in the SB patients and controls. During wakefulness, all of the series of jaw movements were associated with eye movements. Most of cycles of jaw movements (SB patients: 88.89%, 200/225; Controls: 95.11%, 214/225) were associated with slow eye movements and most of the eye movements (SB patients: 52.50%, 105/200; Controls: 61.21%, 131/214) were vertical. There were significant correlations between the durations of episodes of eye movements and RMMAs/SB during sleep and between the duration of episodes of eye movements and duration of series of jaw movements during wakefulness in the SB patients and controls.

CONCLUSIONS

Most of RMMAs/SB episodes during sleep and jaw movements during wakefulness are associated with eye movements in SB patients and normal controls.

Critical Issues in Dental and Medical Management of Obstructive Sleep Apnea

This critical review focuses on obstructive sleep apnea (OSA) and its management from a dental medicine perspective. OSA is characterized by ≥10-s cessation of breathing (apnea) or reduction in airflow (hypopnea) ≥5 times per hour with a drop in oxygen and/or rise in carbon dioxide. It can be associated with sleepiness and fatigue, impaired mood and cognition, cardiometabolic complications, and risk for transportation and work accidents. Although sleep apnea is diagnosed by a sleep physician, its management is interdisciplinary. The dentist’s role includes 1) screening patients for OSA risk factors (e.g., retrognathia, high arched palate, enlarged tonsils or tongue, enlarged tori, high Mallampati score, poor sleep, supine sleep position, obesity, hypertension, morning headache or orofacial pain, bruxism); 2) referring to an appropriate health professional as indicated; and 3) providing oral appliance therapy followed by regular dental and sleep medical follow-up. In addition to the device features and provider expertise, anatomic, behavioral, demographic, and neurophysiologic characteristics can influence oral appliance effectiveness in managing OSA. Therefore, OSA treatment should be tailored to each patient individually. This review highlights some of the putative action mechanisms related to oral appliance effectiveness and proposes future research directions.

Temporomandibular disorders: improving outcomes using a multidisciplinary approach

Patients with temporomandibular disorders (TMD) can become very complex. This article aims to highlight the importance of the multimodal and multidisciplinary approach in this type of patients to improve clinical outcomes. At present we have innumerable techniques and tools to approach this type of patients from a biopsychosocial model where active and adaptive type treatments are fundamental. There are various health professions that have competence in the treatment of TMD, however, although in the most complex cases should be treated simultaneously, still too many patients receive unique treatments and only from one point of view. This review exposes the treatments available from a clinical-scientific perspective and also emphasizes the importance of working in specialized units with those professionals who have competencies on the different conditions that may occur.

Heart rate changes associated with rhythmic masticatory muscle activities and limb movements in sleep bruxers: Preliminary findings

Objective: To investigate the relationship of rhythmic masticatory muscle activities (RMMAs) and limb movements (LMs) with heart rate (HR) acceleration. Methods: The amplitude and duration of HR increases, the time to reach peak HR associated with RMMAs/LMs during sleep, duration of movement events, and their relationships with cortical arousal levels were determined in 9 sleep bruxers and 10 normal controls. Results: A total of 48.15% and 49.44% HR increased before the onset of RMMAs/LMs in the sleep bruxers and controls, respectively. All of the parameters of HR increases were significantly different between the sleep bruxers and the controls (p < 0.05-0.001) and between different cortical arousal levels (p < 0.01), and the duration of RMMAs/LMs was positively correlated with the parameters (Sleep bruxers: r² = 0.18-0.88, p < 0.0001; Controls: r² = 0.16-0.78, p < 0.0001). Discussion: These data suggest the HR increases are associated with the movement events and changes in cortical arousal levels in the sleep bruxers and controls. Abbreviations: LMs: Limb movements; HR: Heart rate; RMMAs: Rhythmic masticatory muscle activities; SB: Sleep bruxism; PSG: Polysomnographic; EEG: Electroencephalographic; PLMS: Periodic leg movements; SSRIs: Selective serotonin reuptake inhibitors; ECG: Electrocardiographic; EOG: Electrooculographic; EMG: Electromyographic; SD: Standard deviation; Fig: Figure; SEM: Standard error of mean; N1: Non-rapid eye movement sleep stage 1; N2: Non-rapid eye movement sleep stage 2; N3: Non-rapid eye movement sleep stage 3; REM: Rapid eye movement ; NA: No arousal; mAR: Microarousal; AW: Awakening.

Awake teeth grinding in participants with canine guidance or group function: Effect on diaphragm EMG activity, heart rate, and oxygen saturation

Objective: To compare the effect of canine guidance or group function on diaphragm activity, heart rate, and oxygen saturation during awake teeth grinding at different body positions. Methods: Fifty healthy participants, 25 with canine guidance and 25 with group function, were included. Bilateral electromyographic (EMG) recordings of the diaphragm (DIA) during awake teeth grinding were performed in standing, seated upright, and right lateral decubitus positions. Simultaneously, heart rate and oxygen saturation were measured. Results: EMG activity of the DIA muscle was similar in the working side and non-working side between participants with canine guidance and group function in the different body positions studied. The heart rate and oxygen saturation showed no significant differences between the two groups. Conclusion: EMG activity of the DIA muscle, the heart rate, and oxygen saturation during teeth grinding are not significantly influenced by the type of laterotrusive occlusal scheme.

Association between bruxism and symptomatic gastroesophageal reflux disease: A case-control study

OBJECTIVES

To examine the relation between bruxism and gastroesophageal reflux disease (GERD) and the contribution of depression, anxiety and impaired sleep quality to that association.

METHODS

A three-centre case-control study was conducted consisting of 887 consecutive clinically-diagnosed bruxism patients aged 18-75 years and 887 matched controls. Diagnosis of GERD was based on the Montreal definition: moderate/severe symptoms ≥ one day/week or mild symptoms ≥ two days/week. Logistic regression was used to evaluate the association between bruxism and GERD. Mediation analyses were used to test whether the association between bruxism and GERD was mediated by depression, anxiety or impaired sleep quality.

RESULTS

Binary logistic regression identified that GERD was associated with bruxism (odds ratio, 6.87; 95% confidence interval (CI), 4.34-10.88). This association was stronger in females (odds ratio, 12.27; 95% CI, 5.81-25.91) than in males (odds ratio, 3.99; 95% CI, 2.17-7.32). Multinomial logistic regression identified that GERD was associated with all types of bruxism (sleep bruxism alone, odds ratio, 6.71, 95% CI, 4.22-10.68; awake bruxism alone, odds ratio, 13.06, 95% CI, 5.32-32.05; overlap of sleep bruxism and awake bruxism, odds ratio, 6.48, 95% CI, 3.05-13.77). Ordinal logistic regression identified that longer GERD duration (> 2 years vs ≤ 2 years) was associated with bruxism frequency (odds ratio, 1.50; 95% CI, 1.10-2.05). Mediation analyses found that the association between bruxism and GERD was partially-mediated through depression, anxiety and impaired sleep quality.

CONCLUSIONS

Clinically-diagnosed bruxism is associated with symptomatic GERD and is partially-mediated through depression, anxiety and impaired sleep quality.

CLINICAL SIGNIFICANCE

Because bruxism is strongly associated with symptomatic GERD and patients with frequent bruxism symptoms tend to suffer from GERD for extensive time-periods, dentists should consider evaluation of GERD status as an elemental part of the medical examination of bruxism, especially severe bruxism.

Generation of neural cells using iPSCs from sleep bruxism patients with 5-HT2A polymorphism

PURPOSE

Sleep bruxism (SB) is classified as a sleep-related movement disorder characterized by grinding and clenching of the teeth during sleep, which is responsible for a variety of clinical problems such as abnormal tooth attrition and fracture of teeth or roots. Little is known about the etiology of SB. Our previous study identified a genomic association of the serotonin 2A receptor (5-HT2A) single nucleotide polymorphism (SNP), rs6313 C>T, with SB, where the C allele carrier is associated with a 4.25-fold increased risk of SB. Based on this finding, the aim of this study was to generate of neural cells using SB patient-specific induced pluripotent stem cells (iPSCs).

METHODS

Two SB patients with C/C genotype of rs6313 and two controls with T/T genotype were screened by laboratory-based polysomnographic recordings and the TaqMan genotyping assay. Four lines of iPSCs, two from SB patients and two from controls, were established from peripheral blood mononuclear cells by introduction of reprogramming factors. We performed quality control assays on iPSCs using expression of markers for undifferentiated pluripotent cells, immunostaining for pluripotency markers, a three-germ layer assay, and karyotype analysis. The established iPSCs were differentiated into neurons using the neurosphere culture system. 5-HT2A gene expression in these neurons was evaluated by quantitative real-time PCR.

RESULTS

Patient-specific iPSCs were successfully differentiated into neurons expressing 5-HT2A.

CONCLUSIONS

This report is the first successful generation of neural cells using iPSCs from sleep bruxism patients with 5-HT2A polymorphism, which has the potential to elucidate the etiology and underlying mechanism of SB.