Temporal association between sleep apnea-hypopnea and sleep bruxism events

Sleep Disorders Affecting Prognosis of Dental Treatment

This study provided an overview of the knowledge on the main sleep-related disorders and conditions affecting the prognosis of dental treatment: sleep bruxism (SB), obstructive sleep apnea (OSA), and gastroesophageal reflux disease (GERD). Current scientific evidence seems to suggest that these phenomena (ie, SB, OSA, GERD) belong to a circle of mutually relating sleep disorders and conditions where dental practitioners can play a key role in diagnosis and treatment.

Sleep bruxism and sleep respiratory disorders in children and adolescents: A systematic review

OBJECTIVE

Sleep bruxism (SB) is a repetitive rhythmic and nonrhythmic activity. It can be a comorbid condition for other disorders, such as sleep breathing disorders (SBD). However, a clear causal link between these factors is yet to be established. Moreover, this relationship is even more unknown in children. Thus, this systematic review aimed to determine the relationship between SB and SBD in children and teenagers and consolidate the current knowledge about the possible association between both phenomena at the pediatric age.

MATERIALS AND METHODS

Advanced searches were performed in five electronic databases with the last search updated on February 1, 2023. The methodological quality of the selected studies was analyzed using the quality assessment tool for experimental bruxism studies.

RESULTS

Twenty-nine of 6378 articles were selected for detailed analyses. Most articles found a comorbid relationship between SB and SBD, though no study analyzed a temporary relationship. Due to the heterogeneity of the studies, a meta-analysis could not be performed.

CONCLUSION

Despite the limitations of this systematic review, it can be concluded that there is an association between SB and SBD in children. However, the level of evidence is low.

Sleep bruxism (SB) may be not associated with obstructive sleep apnea (OSA): A comprehensive assessment employing a systematic review and meta-analysis

Associations between obstructive sleep apnea (OSA) and sleep bruxism (SB) are the subject of discussion but have not been confirmed definitively. Therefore, the objective of this meta-analysis was to examine the relationship between OSA and SB. This systematic review was conducted in accordance with PRISMA 2020 guidelines. PubMed, Embase and Web of Science were screened up to February 2024. The risk of bias was assessed with the Joanna Briggs Institute tool. 2260 records were identified, but only 14 studies were included. The odds of SB presence in OSA did not differ from the control group (OR: 1.23, 95 % CI: 0.47-3.20). The chance of SB compared to controls also did not differ in mild OSA (OR: 1.56, 95 % CI: 0.76-3.18), in moderate OSA (OR: 1.51, 95 % CI: 0.77-2.94) and in severe OSA (OR: 1.50, 95 % CI: 0.68-3.29). Additionally, the odds of SB were not increased in moderate OSA in comparison to mild OSA (OR: 1.14, 95 % CI: 0.63-2.94), in severe OSA compared to moderate OSA (OR: 1.31, 95 % CI: 0.61-2.79) or in severe OSA compared to mild OSA (OR = 1.42, 95 % CI: 0.69-2.93). The presence of SB in OSA did not differ between genders (OR: 2.14, 95 % CI: 0.65-7.05). The quality of the major studies included is low; therefore, the noted lack of correlation between OSA and SB may require further research. The relationship between OSA and SB seems to be multi-faceted. Presented results should not exempt clinicians from exact diagnosis of concomitant sleep conditions in OSA subjects.

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.

Effects of the low Fowler's sleep position and methazolamide treatment on sleep bruxism: A randomized controlled trial

Intracranial pressure is one of the determinants of sympathetic activities, and sleep bruxism is associated with increased sympathetic activities. This study aimed to investigate effects of the low Fowler's sleep position and methazolamide treatment on the occurrence of rhythmic masticatory muscle activities/sleep bruxism episodes in patients with sleep bruxism in a randomized controlled trial. Polysomnographic recordings were performed on the patients with sleep bruxism sleeping in the low Fowler's (15°-30°) or supine position (n = 11), and with methazolamide or placebo treatment (100 mg, 3-4 hr before bedtime, P.O., n = 9), and changes in sleep variables and heart rate variance during sleep in the low Fowler's position or with methazolamide treatment were determined. Sleep bruxism index, number of masseter muscle electromyographic bursts per hour of sleep, ratio of rhythmic masticatory muscle activities/sleep bruxism duration to the total sleep duration, index of total limb movements, index of limb movements with rhythmic masticatory muscle activities, and number of sleep bruxism clusters per hour of sleep in the low Fowler's position and after methazolamide intake were significantly smaller (p < 0.05-0.001) than those in the supine position and after placebo intake, respectively. The low-frequency heart rate variance powers during non-rapid eye movement sleep stage 2 (N2) in the low Fowler's position and with methazolamide treatment were significantly lower (p < 0.05) than those during sleep in the supine position and with placebo treatment, respectively. In conclusion, sleep in the low Fowler's position and methazolamide treatment were associated with significant decreases in the occurrence of rhythmic masticatory muscle activities/sleep bruxism episodes, which might be due to a reduction in intracranial pressure and sympathetic activities mainly during non-rapid eye movement sleep stage 2.

Focus of dental sleep medicine on obstructive sleep apnea in older adults: A narrative review

PURPOSE

To review dental sleep medicine in older adults based on the literature.

STUDY SELECTION

This narrative review focuses on sleep physiology, common sleep disorders, and obstructive sleep apnea (OSA) in older adults and their management.

RESULTS

Sleep physiology differs between older and younger adults, with sleep disturbances occurring more frequently in older adults. The prevalence of insomnia increases in older adults due to age-related changes in sleep physiology. Insomnia, sleep-disordered breathing, periodic limb movement disorder, restless legs syndrome, and rapid eye movement (REM) sleep behavior disorder are common sleep disorders in older adults. OSA is more prevalent in older adults, and its effects on them are considered more substantial than those on younger adults. The treatment of older patients with mandibular advancement devices may be less effective and more complex owing to potential impairments in oral and dental health. Furthermore, the prevalence of edentulism in older adults is decreasing while life expectancy is increasing.

CONCLUSIONS

As older adults have comorbidities that affect sleep quality, dentists should consider the effects of sleep physiology and sleep disorders in these patients. OSA may decrease the quality of life and increase the risk of developing other diseases. Therefore, dentists proposing treatment with mandibular advancement devices need to inform patients of their potential lack of efficacy and the requirement for careful follow-up owing to known and unknown side effects.

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

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

Is there an association between sleep bruxism and obstructive sleep apnea? A case-control polysomnographic investigation

OBJECTIVES

To estimate the statistical and epidemiological association between Sleep bruxism (SB) and Obstructive sleep apnea (OSA) based on OSA severity, and to describe sleep data findings within the analyzed population.

METHODS

A case-control study (N = 37) was conducted on subjects with and without OSA. All subjects underwent a full-night polysomnographic recording at the Sleep Unit (Clinical Neurophysiology Department) of San Carlos University Hospital. The diagnosis and severity of OSA were determined using ICSD-3 and AASM-2.6 scoring. The definitive SB diagnosis was obtained through a self-report test, physical examination, and PSG recordings. Variables used to study the association between both conditions included the apnea and hypopnea episodes, the Apnea-hypopnea index (AHI), the number of SB episodes per night, and the bruxism index. Chi2, correlations, and ANOVA were calculated. The epidemiological association was calculated using the OR.

RESULTS

SB showed an epidemiological association with OSA, with an OR of 0.15 (0.036-0.68), suggesting it could be considered a protective factor (p < 0.05). OSA patients presented fewer average SB episodes (6.8 ± 12.31) than non-OSA patients (25.08 ± 31.68). SB episodes correlated negatively (p < 0.05) with the AHI and the number of hypopneas (p < 0.05). The average number of SB episodes was significantly higher in patients with mild OSA compared to those with severe OSA.

CONCLUSIONS

In this sample of patients with subclinical and mild OSA, SB may act as a protective factor. However, confirmation of these results with a larger sample size is necessary.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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.

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.

Prevalence of bruxism in obstructive sleep apnea syndrome (OSAS) patients: A systematic review conducted according to PRISMA guidelines and the cochrane handbook for systematic reviews of interventions

BACKGROUND

Sleep bruxism (SB) and obstructive sleep apnea syndrome (OSAS) are two sleep-related conditions that have been associated with significantly conflicting results in literature. Understanding the prevalence of bruxism among OSA patients is crucial for identifying possible comorbidities and optimising treatment strategies.

OBJECTIVE

This systematic review aimed at analysing the prevalence of SB in OSAS sufferers and understanding the association between the two.

METHODS

Five online databases were searched for relevant articles in accordance with the PRISMA guidelines for conduction of systematic reviews. Studies reporting the prevalence of bruxism in OSAS patients and diagnosed through clinical assessments or polysomnography were included. Data extraction and quality assessment were performed independently by two reviewers. Methodological quality of the included studies was assessed using Risk of Bias In Non-randomised Studies of Interventions (ROBINS-I).

RESULTS

A thorough search of literature yielded only two studies were eligible for this review. SB was found to be significantly present in the OSAS group. Despite methodological variations, the majority of studies reported higher rates of bruxism in OSAS patients compared to the general population or control groups.

CONCLUSION

The results of this systematic review point to a significant association between bruxism and obstructive sleep apnea. Further research is required to determine a more precise prevalence rate and investigate the potential therapeutic implications of the bruxism-OSAS association that uses a standardised assessment techniques and larger sample sizes.

Frequency distribution of the number and amplitude of electromyographic waveforms of the masseter muscle during sleep in patients with a clinical diagnosis of sleep bruxism

OBJECTIVE

This study aimed to clarify frequency distribution of number and peak amplitude of electromyographic (EMG) waveforms of sleep bruxism (SB) in outpatients with clinical diagnosis of SB (probable bruxer: P-bruxer).

METHODS

Subjects were 40 P-bruxers. Masseteric EMG during sleep was measured at home using a wearable EMG system. EMG waveforms with amplitude of more than two times the baseline and with duration of 0.25 s were extracted as SB bursts. Clusters of bursts, i.e. SB episodes, were also scored.

RESULTS

There were large variations among the subjects in numbers of SB bursts and episodes and in burst peak amplitude. As for burst peak amplitude within a subject, a wide right-tailed frequency distribution was shown with the highest frequency at the class of 5-10% maximum voluntary contraction.

CONCLUSION

The number and amplitude of SB waveforms for P-bruxers were distributed over a wide range, indicating the existence of large individual differences.

Sleep bruxism in children, from evidence to the clinic. 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 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.

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.

Sleep-Related Breathing Disorders in Children—Red Flags in Pediatric Care

Objectives: In recent years, we have witnessed a growing interest in pediatric sleep-related breathing disorders (SRBD). Although a Pediatric Sleep Questionnaire (PSQ) exists and was found reliable in screening SRBD in children, many of the children remain underdiagnosed. The aim of the present study was to define anamnestic and clinical findings that can serve as red flags indicating the presence of SRBD in children. Methods: 227 children aged 4–12 years old were evaluated with regard to the following parameters: (i) anamnestic variables (e.g., general state of health, oral habits, bruxism, esophageal reflux, sleep continuity, snoring); (ii) clinical parameters (e.g., oral mucosa, palate, tonsils, tongue, floor of the mouth, angle classification, gingival health, caries risk) and (iii) presence of SRBD (through the PSQ). Results: Significant differences between children with and without SRBD were observed regarding continuous sleep, developmental delay, mouth breathing, and snoring. Taking medications for ADHD increased the odds of SRBD in children by over seven times, non-continuous sleep increased the odds of SRBD by six times, mouth breathing increased the odds by almost five times, and snoring increased the odds by over three times. Conclusions: Child caregivers from various fields (dentists, orthodontists, pediatric physicians, school nurses) should actively inquire about disturbed sleep, medications for ADHD, snoring, and mouth breathing among their young patients. Initial screening through a few simple questions may help raise red flags that can assist in the early detection of SRBD in children and lead to proper diagnosis and treatment.

Sleep bruxism and obstructive sleep apnea: association, causality or spurious finding? A scoping review

Study Objectives

To evaluate the available evidence on the putative relationships between sleep bruxism (SB) and, obstructive sleep apnea (OSA) to assess the extent of research on this topic, and to formulate suggestions for future research.

Methods

A scoping review including studies examining temporal and overall association and prevalence of SB and OSA was performed. Six main databases and gray literature were searched. The studies selection was conducted by three independent reviewers. A narrative synthesis of the results was carried out.

Results

Thirteen studies in adults and eight studies in children were finally included. The median of concomitant conditions prevalence was 39.3% in adults and 26.1% in children. Marked methodological variability was identified among studies in adults and even more when we compared detection methods in children. No significant association between OSA and SB emerged in most studies in adults, while an association may be possible in children.

Conclusions

Based on the current literature, it is not possible to confirm that there is a relationship between SB and OSA in adults. In patients under pediatric care, although this association seems plausible, there is currently insufficient supportive evidence. Standardized validated methodologies for identifying SB should be consistently used in both populations before reaching any conclusion regarding such association. Furthermore, assessment of shared phenotypes between patients with SB and patients with OSA may reveal new insights that will contribute to personalized approaches aiming to optimize the management of such comorbidities.

The effects of mandibular advancement appliance therapy on the sequence of jaw-closing muscle activity and respiratory events in individuals with obstructive sleep apnea

Purpose

To determine the effects of a mandibular advancement appliance (MAA) on sequences of jaw-closing muscle activity (JCMA) and apneic or hypopneic event (AHE) in individuals with obstructive sleep apnea (OSA).

Methods

Individuals with OSA were included in a secondary analysis of a randomized controlled crossover trial, in which two ambulatory polysomnographic recordings were performed: one with MAA in situ and the other without MAA. A time span of 16 s between JCMA and AHE was applied to classify JCMAs into four sequences: (1) JCMA occurs before AHE (B-type); (2) both events occur simultaneously (S-type); (3) JCMA occurs after AHE (A-type); and (4) JCMA is time-unrelated to AHE (U-type). The effects of MAA on the distribution of these sequences were analyzed by Wilcoxon signed-rank test.

Results

Among 16 individuals (10 men, mean age 51.3 ± 8.5 years) baseline apnea–hypopnea index and JCMA index were 23.8 ± 16.0 events/h and 10.8 ± 10.3 events/h, respectively. In both conditions, i.e., without and with MAA, most JCMAs were U-type (48% and 65%, respectively), followed by A-type (41% and 22%), B-type (25% and 21%), and S-type (2% and 1%). With MAA in situ, only the A-type JCMA index decreased significantly (P = 0.005), while B-type, S-type, and U-type JCMA indices did not change significantly (all P > 0.05).

Conclusion

MAA therapy only significantly reduces the jaw-closing muscle activities that occur after apneic or hypopneic events in individuals with OSA.

Trial registration

www.clinicaltrials.gov (NCT02011425); December 13, 2013.

Associations between sleep bruxism and other sleep-related disorders in adults: a systematic review

OBJECTIVE

Systematic reviews on sleep bruxism (SB) as a comorbid condition of other sleep-related disorders are lacking. Such reviews would contribute to the insight of sleep clinicians into the occurrence of SB in patients with other sleep-related disorders, and into the underlying mechanisms of such comorbid associations. This systematic review aimed: 1. to determine the prevalence of SB in adults with other sleep-related disorders; and 2. to determine the associations between SB and other sleep-related disorders, and to explain the underlying mechanisms of these associations.

METHODS

A systematic search on SB and sleep-related disorders was performed in PubMed, Embase, Cochrane Library, and Web of Science to identify eligible studies published until May 15, 2020. Quality assessment was performed using the Risk of Bias Assessment tool for Non-randomized Studies.

RESULTS

Of the 1539 unique retrieved studies, 37 articles were included in this systematic review. The prevalence of SB in adult patients with obstructive sleep apnea, restless leg syndrome, periodic limb movement during sleep, sleep-related gastroesophageal reflux disease, REM behavior disorder (RBD), and sleep-related epilepsy was higher than that in the general population. The specific mechanisms behind these positive associations could not be identified.

CONCLUSIONS

SB is more prevalent in patients with the previously mentioned disorders than in the general population. Sleep arousal may be a common factor with which all the identified disorders are associated, except RBD and Parkinson's disease. The associations between SB and these identified sleep-related disorders call for more SB screening in patients with the abovementioned sleep-related disorders.

Temporal relationship between sleep-time masseter muscle activity and apnea-hypopnea events: A pilot study

BACKGROUND

Obstructive sleep apnea (OSA) is the most common sleep disorder due mainly to peripheral causes, characterized by repeated episodes of obstruction of the upper airways, associated with arousals and snoring. Sleep bruxism (SB) is a masticatory muscle activity during sleep that is characterized as rhythmic (phasic) or nonrhythmic (tonic) and is not a movement disorder or a sleep disorder in otherwise healthy individuals. Given the potentially severe consequences and complications of apnea, the concurrent high prevalence of SB in daily dental practice, getting deeper into the correlation between these phenomena is worthy of interest..

STUDY OBJECTIVES

The aim of this study was to investigate the correlation between SB-related masseter muscle activity (MMA) and apnea-hypopnea events as well as to assess their temporal sequence.

METHODS

Thirty (N = 30) patients with sleep respiratory disorders and clinical suspicion of sleep bruxism (SB) were recruited. Ambulatory polygraphic recording was performed to detect apnea-hypopnea events (AHEs) and sleep bruxism episodes (SBEs). Pearson test was used to assess the correlation between apnea-hypopnea index (AHI) and SB index (SBI). A 5-s time window with respect to the respiratory events was considered to describe the temporal distribution of SBEs. Furthermore, SBI was compared between groups of patients with different AHI severity (i.e., mild, moderate and severe) using ANOVA.

RESULTS

On average, AHI was 27.1 ± 21.8 and SBI 9.1 ± 7.5. No correlation was shown between AHI and SBI. Most of SBEs (66.8%) occurred without a temporal relationship with respiratory events. Considering OSA, 65.7% of SBEs occurred within 5 s after AHEs, while in the case of central apnea (CA) 83.8% of SBEs occurred before the respiratory event. The participants with severe apnea (N = 9) show a tendency to have higher bruxism indexes when compared to patients with mild (N = 11) and moderate apnea (N = 10).

CONCLUSIONS

Findings suggest that: 1. At the study population level, there is no correlation between AHI and SBI, as well as any temporal relationship between SBEs and respiratory events. 2. Specific patterns of temporal relationship might be identified with future studies focusing on the different types of apnea-hypopnea events and bruxism activities.

Prevalence of Bruxism among the Students of Gulf Medical University: A Cross-Sectional Questionnaire Study

Introduction:

Bruxism is a multifactorial phenomenon that involves grinding or clenching of teeth. The parafunctional habit includes abnormal tooth wear, tooth fracture, pain, and tooth mobility, along with headaches and facial muscle hypertrophy. It is imperative for students to be conscious of teeth grinding along with its possible causes. The student will be alert to visit the dentist if required and contribute to the recognition of etiological factors, to eliminate them.

Objective:

This study aims to find the prevalence and understanding of bruxism among Gulf Medical University (GMU) students.

Materials and Methods:

A cross-sectional, questionnaire-based study was conducted among 451 GMU students. The parameters for data collection were age, gender, prevalence, associated signs and symptoms, causes, genetic predisposition, time of day, and effect on the appearance of teeth.

Results:

While 35.9% were unaware, 41.7% of our samples reported bruxism. The majority recognized temporomandibular joint and facial pain as causative, and 24.8% reported symptoms. Headache (26.4%) was prime and 7.5% were associated with fracture and abnormal tooth wear to bruxism (38.1%) experienced night bruxism. A significant number of students (32.4%) identified abnormal anterior teeth relationship as the cause and (64.3%) associated bruxism and esthetics.

Conclusion:

Nearly 41.7% of the students reported bruxism. Around 35.9% of the samples were uninformed. Nearly 20.8% believed that bruxism had genetic relevance. Nearly 51.9% of the participants were asymptomatic. Around 38.1% had night bruxism and 32.4% identified abnormal anterior teeth relationship as the cause. The majority of the sample (64.3%) connected bruxism to negative effects on teeth and esthetics.

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.

Sleep Bruxism and SDB in Albanian Growing Subjects: A Cross-Sectional Study

Background: The aim of this study was to evaluate a possible correlation between sleep bruxism and risk factors of developing obstructive sleep apnea syndrome (OSAS) in a sample of growing subjects and to assess parental awareness about sleep bruxism in their children. Methods: The sample was composed of 310 subjects (173 females and 137 males), with a mean age of 8.9 years, attending "Ndre Mjeda" school of Tirana (Albania). All parents of the children participating in the study were asked to fill in a questionnaire manually or via a digital version. The questionnaire was composed of three sections: personal data, sleep quality data, and OSAS risk factors, and it was filled out by both parents. Results: Of our samples, 41.3% presented with bruxism, and 16.5% of the parents ground their teeth. Oral breathing was reported in 11.9% of the subjects, and among these, 40% of the subjects were affected by bruxism (p > 0.05). Of the subjects, 18.7% snore overnight. Comparing it with sleep bruxism, the two phenomena are often related (p = 0.00). Conclusions: Heredity, night-sweating, nycturia, oral breathing, and snoring seem to have a significant correlation with bruxism.

Determinants of probable sleep bruxism in a pediatric mixed dentition population: a multivariate analysis of mouth vs. nasal breathing, tongue mobility, and tonsil size

OBJECTIVES

This study aims to identify structural and functional craniofacial characteristics that correlate with higher incidence of 'probable' sleep bruxism in children.

METHODS

From March 2018 until March 2019, a cross-sectional clinical study was performed with ninety-six healthy children ages 6-12 years who presented for routine dental examination at the UCLA pediatric dental clinic. Variables of interest included: (1) assessment of probable bruxism based on parental awareness on the frequency of tooth grinding during sleep and clinical signs of bruxism based on tooth wear; (2) parental reports of mouth breathing while awake and asleep, snoring during sleep, difficulty breathing and/or gasping for air during sleep; (3) parental reports of psychosocial distress; (4) assessment of tonsil hypertrophy, tongue mobility, and nasal obstruction. Three pediatric dental residents were calibrated to perform the clinical data collection. All dental residents were graduated dentists with licensure and at least one year of experience examining children. The methodology to take the specific measurements administered in the manuscript were calibrated between the data-collectors under the supervision of a board-certified pediatric dentist and orthodontist (AY).

RESULTS

The mean age of individuals was 8.9 (SD = 1.9) years with a gender distribution of 46 males and 50 females. There were 23 out of the 96 (24%) individuals who met the diagnostic criteria for probable sleep bruxism (PSB). Sleep Disturbance Scale for Children (SDSC) scores were significantly elevated among children positive for PSB, indicating that they are at higher risk for sleep disturbances (PSB-positive: 45.1 ± 13.0, PSB-negative: 34.8 ± 5.5; p < 0.0001). Impaired nasal breathing, parental reports of mouth breathing when awake or asleep, restricted tongue mobility, and tonsillar hypertrophy were found to be significant risk factors for PSB. Exploratory analysis further suggests a synergistic effect between tonsil hypertrophy, restricted tongue mobility, and nasal obstruction. The incidence of probable sleep bruxism among individuals without any of the exam findings of tonsillar hypertrophy, restricted tongue mobility, and nasal obstruction was 5/58 (8.6%), whereas the incidence of PSB among individuals with all three exam findings was 10/11 (90.9%), p < 0.0001. Among the 23 individuals with PSB, however, there were n = 5 (21.7%) who did not have any of the three exam findings, suggesting an additional role of psychosocial distress, postural maladaptation, malocclusion, or other factors in the etiology of sleep bruxism.

CONCLUSION

This study shows that tonsil hypertrophy, restricted tongue mobility, and nasal obstruction may have a synergistic association on the presentation of PSB. Dentists should evaluate for tonsillar hypertrophy, restricted tongue mobility, and nasal obstruction in the evaluation of PSB, as these exam findings are highly prevalent in the majority of cases.

The effects of mandibular advancement appliance therapy on jaw-closing muscle activity during sleep in patients with obstructive sleep apnea: a 3-6 months follow-up

STUDY OBJECTIVES

The main aim of this study was to investigate the effects of mandibular advancement appliance (MAA) therapy on jaw-closing muscle activity (JCMA) time-related to respiratory arousals, and on JCMA time-related to nonrespiratory arousals in patients with obstructive sleep apnea.

METHODS

Eighteen patients with OSA (mean ± standard deviation = 49.4 ± 9.8 years) with a mean ± standard deviation apnea-hypopnea index of 22.0 ± 16.0 events/h of sleep participated in a randomized controlled crossover trial in which two ambulatory polysomnographic recordings, 1 with an MAA in situ and another without the MAA in situ, were performed. JCMA was quantified as the sum of rhythmic masticatory muscle activities and other orofacial activities.

RESULTS

Significant reductions in the apnea-hypopnea index (Z = -2.984; P = .003), in the respiratory arousal index (Z = -2.896; P = .004), and in the JCMA time-related to respiratory arousal index (Z = -3.434; P = .001) were found with MAA in situ. On the nonrespiratory arousal index, and on the JCMA time-related to nonrespiratory arousal index, MAA had no significant effect (T = 2.23; P = .82; and Z = -0.66; P = .51, respectively).

CONCLUSIONS

This study shows that effective mandibular advancement appliance therapy significantly reduces jaw-closing muscle activities time-related to respiratory arousals in OSA patients. Future studies are needed to confirm these findings in obstructive sleep apnea patients with comorbid sleep bruxism.

CLINICAL TRIAL REGISTRATION

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

The face of Dental Sleep Medicine in the 21st century

It becomes increasingly clear that some sleep disorders have important diagnostic and/or management links to the dental domain, hence the emergence of the discipline ‘Dental Sleep Medicine’. In this review, the following topics are discussed: 1. the reciprocal associations between oro‐facial pain and sleep; 2. the associations between sleep bruxism and other sleep‐related disorders; 3. the role of the dentist in the assessment and management of sleep bruxism; and 4. the dental management of obstructive sleep apnoea. From these topics' descriptions, it becomes clear that the role of the dentist in the recognition and management of sleep‐related oro‐facial pain, sleep bruxism and obstructive sleep apnoea is large and important. Since many dental sleep disorders can have severe consequences for the individual's general health and well‐being, it is imperative that dentists are not only willing to take on that role, but are also able to do so. This requires more attention for Dental Sleep Medicine in the dental curricula worldwide, as well as better postgraduate training of dentists who are interested in specialising in this intriguing domain. This review contributes to increasing the dental researcher's, teacher's and care professional's insight into the discipline ‘Dental Sleep Medicine’ as it has taken shape in the 21st century, to the benefit of all patients suffering from dental sleep disorders.

Influence of respiratory allergy and restless sleep on definite sleep bruxism: a cross-sectional clinical study

OBJECTIVE

This cross-sectional clinical study evaluated the associations between sociodemographic, occupational, clinical conditions, psychological and sleep quality variables on definite sleep bruxism (SB).

METHODS

All records obtained from adults (aged 20-60 years) and the elderly (aged >60 years) who had undergone polysomnography (PSG) at a private medical outpatients' clinic from July 2017 to February 2018 were reviewed. Data from a questionnaire, based on the criteria of the American Academy of Sleep Medicine (AASM), were also gathered. Definite SB data pattern distribution was analyzed, and multivariate Poisson regression with robust variance was used to assess the associations between definite SB diagnosis, determined via PSG recordings, and the independent variables. A significance level of 5% was adopted.

RESULTS

A total of 240 individuals were included in the study and the SB prevalence was 7.08% (n = 17). The adjusted Poisson regression analysis revealed association between definitive SB and individuals with respiratory allergy (PR = 3.63; 95% CI:1.01-13; P = 0.047) and restless sleep (PR = 2.97; 95% CI:1.04-8.50; P = 0.042).

CONCLUSION

This study found associations between definite SB and clinical conditions (respiratory allergy) and sleep behavior (restless sleep). Knowledge regarding factors associated with definite SB can contribute to decision making in the clinical setting and management strategies involving a multidisciplinary approach.

[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.

Associations between tooth wear and dental sleep disorders: A narrative overview

Objectives

Tooth wear is a common finding in adult patients with dental sleep disorders. The aim of this paper was to review the literature on the possible associations between tooth wear and the following dental sleep disorders: sleep‐related oro‐facial pain, oral moistening disorders, gastroesophageal reflux disease (GERD), obstructive sleep apnoea syndrome (OSAS) and sleep bruxism.

Methods

A PubMed search was performed on 1 June 2018 using MeSH terms in the following query: Tooth Wear AND (Facial Pain OR Temporomandibular Joint Disorders OR Xerostomia OR Sialorrhea OR Gastroesophageal Reflux OR Sleep Apnea Syndrome OR Sleep Bruxism).

Results

The query yielded 706 reports on tooth wear and the mentioned dental sleep disorders. Several associations between tooth wear and the dental sleep disorders were suggested in the literature. It could be concluded that: (a) tooth wear is associated with dental pain and/or hypersensitivity; (b) oral dryness is associated with tooth wear, oro‐facial pain and sleep bruxism; (c) GERD is associated with tooth wear, oro‐facial pain, oral dryness, OSAS and sleep bruxism; (d) OSAS is associated with oral dryness, GERD and sleep bruxism; and (e) sleep bruxism is associated with tooth wear.

Conclusions

Tooth wear is associated with the dental sleep disorders oro‐facial pain, oral dryness, GERD and sleep bruxism. The dental sleep disorders are interlinked with each other, which leads to indirect associations as well, and makes the consequences of each single condition difficult to disentangle. Knowledge of these associations is clinically relevant, but more research is needed to confirm their validity.

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.

Spontaneous jaw muscle activity in patients with acquired brain injuries-Preliminary findings

PATIENTS

High or excessive parafunctional jaw muscle activity is a frequent complication of acquired brain injury (ABI) and may have some similarities to bruxism. Bruxism has been associated with increased tooth wear, masseter hypertrophy and headaches. The aim of this observational study was to identify the levels of jaw muscle activity from fourteen ABI patients having different functional and cognitive levels in their early phase of neurological rehabilitation (according to their Ranchos Los Amigos Scale (RLAS) score). Nine patients were severely cognitive impairement (RLAS score 1-3): with no or little response to any external stimuli due to low arousal and five patients were with RLAS score 4-8: depending on responses to stimuli and confusion level i.e. defining that patients had enough arousal to respond and react and therefore were able to follow the instructions. A single-channel electromyographic (EMG) device was used to assess the jaw muscle EMG activity in ABI patients for two hours continuously at two different days.

DISCUSSION

The mean (±SD) jaw muscle activity observed in patients with ABI was 46.9±6.5 EMG events/h with a wide range between 1-163 EMG events/h but with no significant difference between days (P=0.230).

CONCLUSION

Irrespective of functional and cognitive ability scores patients with ABI had a wide range of EMG activity. The use of ambulatory single-channel EMG devices might open a path for further studies to determine levels of jaw muscle activity associated with potential side effects in ABI patients.

Scalloped tongue is associated with nocturnal intermittent hypoxia among community-dwelling Japanese: the Toon Health Study

Scalloped tongue is considered as a possible clinical finding of obstructive sleep apnoea (OSA). There are few evidence of the association between scalloped tongue and OSA. To examine the association between scalloped tongue and nocturnal intermittent hypoxia (NIH), a surrogate marker of OSA, among a general Japanese population. Study participants were 398 men and 732 women aged 30-79 years who participated in the Toon Health Study from 2011 to 2014. Scalloped tongue was classified into three categories: none, mild and moderate-to-severe. Moderate-to-severe NIH was defined as the 3% oxygen desaturation index of ≥15 events/h during sleep for one night with pulse oximetry. The multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for moderate-to-severe NIH were calculated according to scalloped tongue categories using a logistic regression model. There were 69 (6·1%) moderate-to-severe NIH cases in this population. The multivariable-adjusted ORs (95% CIs) of moderate-to-severe NIH were 1·59 (0·85-2·95) for mild and 2·39 (1·10-5·17) for the moderate-to-severe scalloped tongue group compared with the group without scalloped tongues. When stratified by overweight status (BMI <25 or ≥25 kg m^-2 ), the respective ORs (95% CIs) were 2·83 (1·06-7·55) and 4·74 (1·28-17·49) among overweight individuals, and 0·94 (0·40-2·70) and 1·52 (0·57-4·05) among non-overweight individuals. Scalloped tongue was associated with higher prevalence of moderate-to-severe NIH among the general Japanese population and this association was more evident in overweight individuals.

Oral Appliances in Obstructive Sleep Apnea

Oral appliance therapy (OAT) has become an increasingly popular nonsurgical option for the treatment of obstructive sleep disorders. Recent research supports its efficacy and high levels of compliance for patients with obstructive sleep disorders. Common side effects of OAT include temporomandibular joint-related symptoms, bite changes, and tooth movement. These side effects can be minimized by the use of exercises. The American Academy of Dental Sleep Medicine and the American Academy of Sleep Medicine have released joint clinical practice guidelines for the treatment of obstructive sleep apnea and snoring with OAT.

Grinding patterns in migraine patients with sleep bruxism: a case-controlled study

OBJECTIVES

Details on grinding patterns and types of contact during sleep bruxism in association with migraine headache have not yet been elucidated. This study compared the characteristics of sleep bruxism between patients with migraine and controls.

METHODS

The study included 80 female patients who had been diagnosed with migraine and 52 women with no history of migraine. Grinding patterns were measured using the BruxChecker® (Scheu Dental, Iserlohn, Germany).

RESULTS

There was a significant difference between the two groups in the distribution of grinding patterns at the laterotrusive side (p < 0.001). When the anterior teeth and premolar and molar regions in the two groups were compared, the proportion of the grinding area at all sites was significantly larger in the migraine group than in the control group (p < 0.001).

DISCUSSION

The BruxChecker® showed that there was substantial grinding over a large area among migraine patients, particularly in the molar region.

Weak association between sleep bruxism and obstructive sleep apnea. A sleep laboratory study

PURPOSE

No definitive associations or causal relationships have been determined between obstructive sleep apnea-hypopnea (OSAH) and sleep bruxism (SB). The purpose of this study was to investigate, in a population reporting awareness of both OSAH and SB, the associations between each specific breathing and jaw muscle event.

METHODS

Polysomnography and audio-video data of 59 patients reporting concomitant OSAH and SB history were analyzed. Masseteric bursts after sleep onset were scored and classified into three categories: (1) sleep rhythmic masticatory muscle activity with SB (RMMA/SB), (2) sleep oromotor activity other than RMMA/SB (Sleep-OMA), and (3) wake oromotor activity after sleep onset (Wake-OMA). Spearman's rank correlation coefficient analyses were performed. Dependent variables were the number of RMMA/SB episodes, RMMA/SB bursts, Sleep-OMA, and Wake-OMA; independent variables were apnea-hypopnea index (AHI), arousal index(AI), body mass index(BMI), gender, and age.

RESULTS

Although all subjects had a history of both SB and OSAH, sleep laboratory results confirmed that these conditions were concomitant in only 50.8 % of subjects. Moderate correlations were found in the following combinations (p < 0.05); RMMA/SB episode with AI, RMMA/SB burst with AI and age, Sleep-OMA burst with AHI, and Wake-OMA burst with BMI.

CONCLUSIONS

The results suggest that (1) sleep arousals in patients with concomitant SB and OSAH are not strongly associated with onset of RMMA/SB and (2) apnea-hypopnea events appear to be related to higher occurrence of other types of sleep oromotor activity, and not SB activity. SB genesis and OSAH activity during sleep are probably influenced by different mechanisms.

Sleep-Related Breathing Disorders and Bruxism

Obstructive sleep apnea (OSA) syndrome is a sleep-related breathing disorder, due mainly to peripheral causes, characterized by repeated episodes of obstruction of the upper airways, associated with snoring and arousals. The sleep process fragmentation and oxygen desaturation events lead to the major health problems with numerous pathophysiological consequences. Micro-arousals occurring during sleep are considered to be the main causal factor for night jaw-closing muscles activation called bruxism. Bruxism is characterized by clenching and grinding of the teeth or by bracing or thrusting of the mandible. The causes of bruxism are multifactorial and are mostly of central origin. Among central factors there are secretion disorders of central nervous system neurotransmitters and basal ganglia disorders. Recently, sleep bruxism has started to be regarded as a physiological phenomenon occurring in some parts of the population. In this article we present an evaluation of the relationship between OSA and sleep bruxism. It has been reported that the frequency of apneic episodes and that of teeth clenching positively correlates in OSA. However, clinical findings suggest that further studies are needed to clarify sleep bruxism pathophysiology and to develop new approaches to tailor therapy for individual patients with concomitant sleep bruxism and OSA.