The bruxism construct: From cut‐off points to a continuum spectrum

Parkinson's disease, temporomandibular disorder pain and bruxism and its clinical consequences: a protocol of a single-centre observational outpatient study

INTRODUCTION

A recent questionnaire-based study suggested that bruxism and painful temporomandibular disorders (TMD pain) may be more prevalent in patients with Parkinson's disease (PD) compared with controls. The presence of both bruxism and TMD pain may negatively influence patients' quality of life. The present study is designed to clinically and more objectively investigate the presence of bruxism and TMD pain in patients with PD. The secondary aim of the study is to identify factors associated with bruxism and TMD pain in patients with PD, such as disease severity and dopaminergic medication usage. Furthermore, the presence of tooth wear in patients with PD will be studied as this can be a major consequence of bruxism. Finally, deviations in saliva composition that may contribute to tooth wear will be studied.

METHODS AND ANALYSIS

This is a single-centre observational outpatient study at the Amsterdam University Medical Centres, location VUmc. All patients with a clinical diagnosis of PD will be eligible for inclusion. Participants will fill in a set of questionnaires. Subsequently, patients will be examined clinically for, among others, TMD pain, presence and severity of tooth wear, and deviations in saliva composition. Sleep-time registrations will take place for 5 nights with the GrindCare GC4 (ie, a portable, single-channel electromyographic recorder) to assess sleep bruxism and simultaneously by the use of the BruxApp for 5 days to assess awake bruxism. We will partly use data collected during standard clinical care to minimise patient burden.

ETHICS AND DISSEMINATION

The scientific and ethical aspects of this study protocol have been approved by the Medical Ethics Review Committee of the Amsterdam UMC, location VUmc; NL. 2019.143. Informed consent will be obtained from all participants. The results will be published in a peer-reviewed journal, if relevant presented at conferences, and published as part of a PhD thesis.

TRIAL REGISTRATION NUMBER

NL8307.

Is bruxism associated with changes in neural pathways? A systematic review and meta-analysis of clinical studies using neurophysiological techniques

This study aimed to systematically review the literature to identify clinical studies assessing neuroplasticity changes induced by or associated with bruxism or a tooth-clenching task using neurophysiological techniques. Searches were performed in five electronic databases (PubMed, EMBASE, Scopus, Web of Science, and Google Scholar) in April 2020. This review included clinical studies using neurophysiological techniques to assess neuroplasticity changes in healthy participants before and after a tooth-clenching task or comparing bruxers and non-bruxers. The quality assessment was performed with the Joanna Briggs Institute tool and Grading of Recommendations Assessment, Development, and Evaluation. Meta-analyses were conducted with studies reporting similar comparisons regarding masseter motor evoked potential amplitude and signal change outcomes. Of 151 articles identified in the searches, nine were included, and five proceeded to meta-analysis. Included studies presented moderate to very low methodological quality. From these included studies, eight evaluated bruxers and non-bruxers, of which five of them observed brain activity differences between groups, and three found no differences. Even so, all studies have suggested distinct difference in the central excitability between bruxers and non-bruxers, the meta-analysis revealed no statistically significant differences (P > 0.05). It appears that bruxism seems, indeed, to be associated with distinct differences in the neural pathways related to the control of the jaw-closing muscles, but that considerable variability in terms of classification of bruxism and assessment of neuroplasticity hamper a definite conclusion. Future research projects should take these concerns into consideration in order to further the understanding of bruxism physiology and pathophysiology.

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.

Psychosocial and Behavioral Factors in Awake Bruxism-Self-Report versus Ecological Momentary Assessment

The issue of psychosocial factors and concurrent conditions associated with AB is a relatively new approach in the study of Awake Bruxism (AB). In the present study a population of 84 dental students were assessed for probable AB with two modes of AB assessment: Single point self-report (SR) and ecological momentary assessment through a designated smartphone application (BA). The two assessment modes were compared with regard to their ability to phenotype subjects as far as the following psychosocial and behavioral variables are concerned: Gender; depression; somatization; oral behaviors; chronic pain and associated pain symptoms in the head, neck and scapula. Two-way ANOVA showed main effect of SR for the following variables: Chronic Pain Intensity score (F_(1,49) = 6.441, p < 0.02), migraine/headache (F_(1,81) = 7.396, p < 0.01), pain in neck (F_(1,81) = 6.726, p < 0.05), pain in scapula (F_(1,81) = 8.546, p < 0.005) and the oral behaviors of pushing the tongue forcefully against the teeth (F_(1,81) = 5.222, p < 0.05) and inserting the tongue between the upper and lower teeth (F_(1,81) = 5.344, p < 0.03). The effect of SR on the habit of chewing gum was borderline (F_(1,81) = 3.369, p = 0.07). Main effect of BA was found for depression (F_(1,81) = 6.049, p < 0.05), while the effect of BA on somatization was borderline (F_(1,81) = 3.657, p = 0.059). An interaction between SR and BA groups could be observed for the behavior of biting, chewing or playing with the tongue, cheeks or lips (F_(1,81) = 4.117, p < 0.05). The results suggest that a combination of a single-point self-report referring to the past 30 days, and an ecological momentary assessment supplying information about the actual timing of the report, can help us to better assess AB, as well as increase our ability to define the phenotype of subjects with AB as far as psychosocial and behavioral factors are concerned.

Utility of Smartphone-based real-time report (Ecological Momentary Assessment) in the assessment and monitoring of awake bruxism: A multiple-week interval study in a Portuguese population of university students

PURPOSE

The Ecological Momentary Assessment (EMA) concept was the basis for developing a smartphone application for the on-time report of awake bruxism (AB) activities. This study aims to monitor AB report over time in a population of healthy young adults.

METHODS

A population of young adults recruited among dental students in good general health was recruited. All answered to a questionnaire, including the Oral Behavior Checklist (OBC-1). They were then monitored with a smartphone application for AB report during seven consecutive days and completed three further observation periods (EMA-1, 2 and 3) at one-month intervals. After the third period (EMA-3), participants answered again the OBC questionnaire (OBC-2). Changes over time were described, and Pearson Correlation test was performed to assess the correlation between EMA and OBC items reports. A significance level of p = .01 was set.

RESULTS

Thirty-one University students completed the study protocol. Answers to the OBC showed an increase in the prevalence of self-reported bracing and teeth clenching from the first to second report (38.7%-54.8% and 77.4%-90.3%, respectively). A slight increase in the 'relaxed' condition (62.5%-69.0%) was observed with EMA-based smartphone application over time. No correlation between OBC items and EMA was detected between OBC-1 and EMA-1. A moderate positive correlation in bracing report (+0.509, p = .01) and weak positive correlation in teeth contact report (+0.380, p = .05) were found between OBC-2 and EMA-3.

CONCLUSION

Using a smartphone-based approach to AB report may be helpful to monitor AB over time and increase an individual's awareness to recognise actions such as bracing and teeth contact concerning the single-time report.

Role of occlusal factors on probable bruxism and orofacial pain: Data from the 1982 Pelotas birth cohort study

OBJECTIVES

This study aimed to explore the association between occlusal features and temporomandibular disorder (TMD) pain complaints and probable awake or sleep bruxism METHODS: Path analysis was used to estimate direct, indirect and total effects of occlusal features on probable bruxism and pain-related TMD in adults aged 31 years from the 1982 Pelotas Birth Cohort. A total of 539 cohort members had an oral examination in 2013. Occlusal features were assessed through the Dental Aesthetic Index (DAI), orofacial pain complaints through the TMD pain screener and probable bruxism based on self-reports in combination with clinical findings.

RESULTS

Malocclusions were found in 28.8% of the participants, while awake bruxism was reported in 35.2%, sleep bruxism in 15.2%, and pain-related TMD in 52.5% of the sample. Occlusion had no direct effect on either awake bruxism [standardized coefficient (SC) -0.002; p = 0.995] or pain-related TMD (SC -0.06; p = 0.115). Conversely, probable awake bruxism was associated with pain-related TMD (SC 0.35; p < 0.001). Similar results were found when sleep bruxism was set as the mediator of interest, as malocclusion did not directly affect sleep bruxism (SC 0.05; p= 0.220) nor pain-related TMD (SC -0.06; p = 0.167). A direct effect of sleep bruxism on pain-related TMD was observed with an SC of 0.16 (p < 0.001).

CONCLUSION

Our findings suggested that malocclusion during adulthood did not directly influence probable awake or sleep bruxism nor TMD pain complaints. Instead, probable awake and sleep bruxism was associated with TMD pain complaints.

CLINICAL SIGNIFICANCE

Malocclusion did not impact the presence of bruxism nor TMD complaints in adulthood, but awake and sleep bruxism were associated with TMD pain complaints. The significance of malocclusion should be reconsidered in contemporary dentistry and oral rehabilitation.

Are oral overuse behaviours associated with painful temporomandibular disorders? A cross-sectional study in Portuguese university students

BACKGROUND

Many different types of oral overuse behaviours occur frequently in adult populations with painful temporomandibular disorders (TMDs). Less is known regarding these behaviours and their associations with TMDs in university students.

OBJECTIVES

Test the association between frequency of different oral overuse behaviours evaluated by the Oral Behaviour Checklist (OBC) and the severity of painful TMDs.

METHODS

In this cross-sectional study, 1381 students from 19 universities in the Oporto District, Portugal, completed the Research Diagnostic Criteria for TMD (RDC/TMD) Personal History Questionnaire and the OBC, and they received an RDC/TMD clinical examination. The OBC sum score (ranging from 0 to 84 points) was classified as normal (0 ≤ 16 points), low overuse (17 ≤ 24) or high overuse (≥25). Painful TMD subtypes (myalgia, arthralgia or combined) were identified. Associations were tested using multivariable binary logistic regression models (α = .05), adjusted for age and sex, and referencing the normal parafunction group.

RESULTS

University students with high overuse were more likely to have a painful TMD: myalgia (OR = 1.9, 95% CL: 1.3-3.0); arthralgia (OR = 2.2; 95% CL: 1.4-3.4), combined (OR = 5.0; 95% CL: 3.1-8.1). Students with low overuse were more likely to have only the combined painful TMD (OR = 2.4; 95% CL: 1.4-4.0) but not the individual painful disorders. Of the 21 different behaviours, 13 were reported at least 50% of the time.

CONCLUSIONS

In this university student sample, oral overuse behaviours are widespread, and their overall extent exhibited a dose-response relationship with respect to severity of painful TMDs based on pain and chronicity. Only some behaviours were independently associated with painful TMDs, suggesting the value of further OBC instrument development.

Sleep bruxism and temporomandibular disorders: A scoping review of the literature

OBJECTIVE

To provide a scoping review of the literature by assessing all the English-language papers that investigated the relationship between sleep bruxism (SB) and temporomandibular disorders (TMDs).

STUDY DATA AND SOURCES

A search was performed in the National Library of Medicine (PubMed) and Scopus databases, in order to identify all the articles published assessing the relationship between SB and TMDs, by several different approaches. The selected articles were then structurally read and summarized in PICO tables. The articles were selected independently by the two authors.

STUDY SELECTION

Out of 185 references that were initially retrieved, 47 articles met the inclusion criteria and were thus included in the review. The studies were divided into four categories based on the type of SB assessment: 1. questionnaire/self-report (n = 26), 2. clinical examination (n = 7), 3. electromyography (EMG) (n = 5), and 4. polysomnography (PSG) (n = 9).

CONCLUSIONS

Studies based on questionnaire/self-report SB featured a low specificity for SB assessment, and in general they found a positive association with TMD pain. On the contrary, instrumental studies (i.e., electromyography, polysomnography) found a lower level of association or even a negative relationship between SB and TMD pain. Findings from this updated review confirmed the conclusions of a previous review by Manfredini & Lobbezoo, suggesting that literature findings on the relationship between SB and TMDs are dependent on the assessment strategies that are adopted for SB. Future studies should consider SB as a multifaceted motor behavior that must be evaluated in its continuum spectrum, rather than using a simplified dichotomous approach of presence/absence.

Transitioning to chronic temporomandibular disorder pain: A combination of patient vulnerabilities and iatrogenesis

Background

Based on a variety of studies conducted in recent years, some of the factors that might contribute to the negative treatment responses of some TMD patients have been elucidated.

Methods

This paper describes known vulnerability factors that make individuals susceptible to developing temporomandibular disorders (TMDs), as well as those that contribute to the perpetuation of such problems. In addition, the topic of iatrogenesis is discussed as a major contributor to the negative outcomes that can be seen in this field.

Results

At the patient level, anatomical, psychosocial and genetic factors may contribute to individual vulnerability. The anatomy and pathophysiology of muscles, joints, disc and nerves may all be involved in predisposing to TMD symptoms, especially when the patients have pain elsewhere in the body. Among the psychosocial factors, some features may be elucidated by the DC/TMD axis II, while others (eg illness behaviour, Munchausen syndrome, lack of acceptance of non‐mechanical approaches) require careful evaluation by trained clinicians. Genetic predisposition to first onset TMDs and to chronification of symptoms has been identified for individuals with certain psychological traits, presence of comorbid conditions and certain abnormal clinical manifestations. Regarding iatrogenesis, sins of omission may influence the clinical picture, with the main ones being misdiagnosis and undertreatment. Joint repositioning strategies, occlusal modifications, abuse of oral appliances, use of diagnostic technologies, nocebo effect and complications with intracapsular treatments are the most frequent sins of commission that may contribute to chronification of TMDs. The patients who present with massive occlusal and jaw repositioning changes combined with persistent severe orofacial pain are not a rarity within TMD and orofacial pain canters; these patients are the most difficult ones to manage because of this horrific combination of negative factors.

Conclusions

The information presented in this paper will help clinicians to understand better why some individuals develop temporomandibular disorders, why some of them will progress to becoming chronic patients, and what the appropriate responses may be.

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.

Signal acquisition and analysis of ambulatory electromyographic recordings for the assessment of sleep bruxism: A scoping review

Background

Ambulatory electromyographic (EMG) devices are increasingly being used in sleep bruxism studies. EMG signal acquisition, analysis and scoring methods vary between studies. This may impact comparability of studies and the assessment of sleep bruxism in patients.

Objectives

(a) To provide an overview of EMG signal acquisition and analysis methods of recordings from limited‐channel ambulatory EMG devices for the assessment of sleep bruxism; and (b) to provide an overview of outcome measures used in sleep bruxism literature utilising such devices.

Method

A scoping review of the literature was performed. Online databases PubMed and Semantics Scholar were searched for studies published in English until 7 October 2020. Data on five categories were extracted: recording hardware, recording logistics, signal acquisition, signal analysis and sleep bruxism outcomes.

Results

Seventy‐eight studies were included, published between 1977 and 2020. Recording hardware was generally well described. Reports of participant instructions in device handling and of dealing with failed recordings were often lacking. Basic elements of signal acquisition, for example amplifications factors, impedance and bandpass settings, and signal analysis, for example rectification, signal processing and additional filtering, were underreported. Extensive variability was found for thresholds used to characterise sleep bruxism events. Sleep bruxism outcomes varied, but typically represented frequency, duration and/or intensity of masticatory muscle activity (MMA).

Conclusion

Adequate and standardised reporting of recording procedures is highly recommended. In future studies utilising ambulatory EMG devices, the focus may need to shift from the concept of scoring sleep bruxism events to that of scoring the whole spectrum of MMA.

Awake Bruxism-Single-Point Self-Report versus Ecological Momentary Assessment

Assessment of awake bruxism (AB) is problematic due to the inability to use continuous recordings during daytime activities. Recently, a new semi-instrumental approach was suggested, namely, ecological momentary assessment (EMA), via the use of a smartphone application. With the application, subjects are requested to report, at least 12 times per day, the status of their masticatory muscle activity (relaxed muscles, muscle bracing without tooth contact, teeth contact, teeth clenching, or teeth grinding). The aim of the present study was to test the association between a single observation point self-report and EMA assessment of AB. The most frequent condition recorded by the EMA was relaxed muscles (ca. 60%) and the least frequent was teeth grinding (less than 1%). The relaxed muscle condition also showed the lowest coefficient of variance over a seven-day period of report. Additionally, only the relaxed muscles and the muscle bracing conditions presented an acceptable ability to assess AB-positive and AB-negative subjects, as defined by single-point self-report questions. The combination between self-report and EMA may have the potential to promote our ability to assess AB. We suggest to re-consider the conditions of teeth contact and teeth grinding while using EMA to evaluate AB.

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.

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

STATEMENT OF PROBLEM

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

PURPOSE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Mapping research trends of temporomandibular disorders from 2010 to 2019: A bibliometric analysis

BACKGROUND

Because of various clinical manifestations and complicated courses, temporomandibular disorders (TMDs) are difficult to treat. Current knowledge about this disease remains insufficient for precise treatment after diagnosis.

OBJECTIVES

The objective of this study is to obtain and map the overall literature trends and most cited keywords in TMDs research.

METHODS

Many indicators, including annual number of publications, country distribution, global cooperations, author contributions, original journals, cited references and keywords, were calculated and evaluated using VOSviewer v.1.6.13, which visualised many results, from the WoSCC database.

RESULTS

A total of 3121 papers on TMDs research were retrieved from 2010 to 2019. The United States produced the most articles published, but the most productive institution was the University of Sao Paulo (Brazil). Researchers and institutions conducting TMDs research have shown a very widespread and close connection. TMDs have been studied worldwide by many research centres. Professor Svensson P was the most published researcher in TMDs research and the Journal of Oral Rehabilitation published the most TMDs research articles. The top cited references mainly presented diagnostic criteria of TMDs. The most cited keywords formed clusters: (a) Anatomical factor of TMDs, (b) Symptoms of TMDs and (c) RDC/TMD, the risk factors, biopsychosocial factors and epidemiology of TMDs.

CONCLUSIONS

The research results provide very valuable data for a thorough understanding of the research status of TMDs and demonstrated international cooperation.

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.

The Relationship between Simple Snoring and Sleep Bruxism: A Polysomnographic Study

Simple snoring is defined as the production of sound in the upper aerodigestive tract during sleep, not accompanied by other pathologies. Sleep bruxism (SB) refers to repetitive phasic, tonic, or mixed masticatory muscle activity during sleep. In this study, we investigated the relationship between simple snoring and SB in patients without obstructive sleep apnea (OSA). A total of 565 snoring subjects underwent polysomnography. After examination, individuals with OSA were excluded from the study group. Finally, 129 individuals were analyzed. The bruxism episode index was positively correlated with maximum snore intensity. Phasic bruxism was positively correlated with snore intensity in all sleep positions. Bruxers had a significantly decreased average and minimum heart rate compared with non-bruxers. Supine sleep position seemed to have a significant impact on snore intensity and SB. In summary, our study showed the relationship between SB, snore intensity, and body position. Phasic bruxism was positively correlated with snore intensity despite the body position, which is an interesting and novel finding.

Music Modulates Awake Bruxism in Chronic Painful Temporomandibular Disorders

OBJECTIVE

In this experimental study, we aimed to determine whether guided music listening (GML) - a music intervention based on models of mood mediation and attention modulation - modulates masticatory muscle activity and awake bruxism in subjects with chronic painful muscular temporomandibular disorders (TMD myalgia, mTMD), a condition causing a significant burden to patients, their families, and healthcare systems.

BACKGROUND

Awake bruxism - a stress behavior characterized by clenching of the teeth - is a strong contributor to chronic mTMD. GML modulates psychological stress and motor responses and could thus reduce muscle activity in chronic musculoskeletal conditions, including mTMD.

METHODS

We recorded the electromyographic (EMG) activity in the right masseter of 14 women with chronic (>6 months) mTMD (median [IQR] = 39.5.3 [24.3] years) and 15 pain-free women (median [IQR] = 30.0 [3.5] years) during a GML session, including 3 music (stressful, relaxing, and participants' favorite music) and a no-music (pink noise) control blocks, each lasting 15 minutes. We measured the motor effort of the right masseter relative to the participants' maximum voluntary contraction (MVC), the muscular effort to maintain mandibular posture (EMG_posture ), and to produce spontaneous awake bruxism episodes (EMG_bruxism ), and the duration and frequency of spontaneous awake bruxism episodes. We tested between-group and within-group (between blocks) differences, as well as the effect of the interaction group by experimental block on these outcome measures.

RESULTS

In both groups, EMG_posture was significantly affected by the interaction group by experimental block (P < .001). Compared to pink noise [mean (95% CI); mTMD: 2.2 (1.6-2.8) %MVC; Controls: 1.1 (0.5-1.7) %MVC], EMG_posture increased during the stressful music block [contrast estimate (95% CI); mTMD: +0.8 (0.7-0.8) %MVC; Controls: +0.3 (0.3-0.4) %MVC; both P < .001], and decreased during the relaxing [mTMD: -0.4 (-0.5 to -0.4) %MVC; Controls: -0.3 (-0.4 to -0.3) %MVC; both P < .001] and favorite [mTMD: -0.5 (-0.6 to -0.5) %MVC; Controls: -0.5 (-0.5 to -0.4) %MVC; both P < .001] music blocks. EMG_posture was greater in mTMD individuals than controls during the favorite music [contrast estimate (95% CI): +1.1 (0.2-1.9) %MVC; P = .019] and the pink noise [+1.1 (0.2-2.0) %MVC; P = .014] blocks. EMG_bruxism was significantly affected by the interaction group by experimental block (P < .001). In mTMD participants, compared to the pink noise block [mean (95% CI); 23.8 (16.0-31.6) %MVC], EMG_bruxism increased during the stressful music block [contrast estimate (95% CI); +10.2 (8.6-11.8) %MVC], and decreased during the relaxing [-6.2 (-8.1 to -4.3) %MVC; P < .001] and favorite [-10.2 (-12.2 to -9.1) %MVC; P < .001] music blocks. These effects were not observed in the control group [mean (95% CI); pink noise: 19.3 (10.9-27.6); stressful: 21.2 (12.9-29.4) %MVC; relaxing: 21.6 (13.3-29.9) %MVC; favorite: 24.2 (15.8-32.7) %MVC; all P > .05]. EMG_bruxism was significantly greater in mTMD participants than controls during the stressful music block [contrast estimate (95% CI): +12.9 (1.6-24.2) %MVC; P = .026). GML did not affect the duration or the frequency of awake bruxism in either group (median [IQR], mTMD: 23.5 [96.7] s, range 1-1300 seconds; Controls: 5.5 [22.5], range 0-246 seconds; P = .108). The frequency of awake bruxism episodes was greater in the mTMD group compared to controls only during the pink noise block (median [IQR], mTMD: 5 [15.3] episodes, range 0-62 episodes; Controls: 1 [3] episode, range 0-27 episodes; P = .046). No significant between-group differences were found in either the overall time spent engaging in awake bruxism (median [IQR], mTMD: 23.5 [96.7] s, range 1-1300 seconds; Controls: 5.5 [22.5], range 0-246 seconds; P = .108), or during each block (all P > .05).

CONCLUSIONS

In subjects with chronic mTMD, relaxing music and the individual's favorite music decreased the muscular effort during spontaneous awake bruxism episodes by 26% and 44% (relative changes), respectively. In contrast, stressful music increases it by about 43%. Because of its positive effects on awake bruxism, GML with selected music could be a promising and non-invasive component of a multimodal approach for the management of chronic mTMD.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

This comprehensive review of the 2019 restorative dental literature is offered to inform busy dentists regarding remarkable publications and noteworthy progress made in the profession. Developed by the Scientific Investigation Committee of the American Academy of Restorative Dentistry, each author brings discipline-specific expertise to 1 of 8 sections of the report: (1) prosthodontics; (2) periodontics, alveolar bone, and peri-implant tissues; (3) implant dentistry; (4) dental materials and therapeutics; (5) occlusion and temporomandibular disorders; (6) sleep-related breathing disorders; (7) oral medicine and oral and maxillofacial surgery; and (8) dental caries and cariology. The report targets important information likely to influence day-to-day dental treatment decisions. Each review is not intended to stand alone but to update interested readers so that they may visit source material when greater detail is desired. As the profession moves toward evidence-based clinical decision-making, an incredible volume of potentially valuable dental literature continues to increase. It is the intention of this review and its authors to provide assistance in negotiating the extensive dental literature published in 2019. It is our hope that readers find this work useful in the clinical management of dental patients.

Correlations between Sleep Bruxism and Temporomandibular Disorders

The aim of this study was to identify correlations between sleep bruxism (SB) and temporomandibular disorders (TMD) as diagnosed by means of the research diagnostic criteria for temporomandibular disorders (RDC/TMD). Sleep bruxism was diagnosed on the basis of I) validated questionnaires, II) clinical symptoms, and III) electromyographic/electrocardiographic data. A total of 110 subjects were included in the study. Fifty-eight patients were identified as bruxers and 52 as nonbruxers. A psychosocial assessment was also performed. An RDC/TMD group-I diagnosis (myofascial pain) was made for 10 out of 58 bruxers, whereas none of the nonbruxers received a diagnosis of this type. No significant differences were found between bruxers and nonbruxers with regard to RDC/TMD group-II (disc displacement) and group-III (arthralgia, arthritis, arthrosis) diagnoses. Somatization was significantly more common among bruxers than nonbruxers. Multivariate logistic regression analysis revealed that somatization was the only factor significantly correlated with the diagnosis of myofascial pain. The results of this study indicate a correlation between myofascial pain, as diagnosed using the RDC/TMD, and somatization. It seems that somatization is a stronger predictor of an RDC/TMD diagnosis of myofascial pain than sleep bruxism is.

Associations between sleep bruxism and (peri-)implant complications: lessons learned from a clinical study

Objective

To report and discuss the lessons learned from the conduct of a clinical study on the associations between sleep bruxism and (peri-)implant complications, the protocol of which has been pre-published.

Materials and methods

A single-center, double-blind, prospective cohort study with a 2 year follow-up was performed in the Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands. Eleven adult participants were included, where an inclusion of 98 was planned. Sleep bruxism was assessed by multiple single-channel electromyographic (EMG) recordings. Main outcomes were biological and technical complications. Results of the study are presented alongside with comments on encountered difficulties.

Results

Insufficient participant recruitment and failed EMG recordings were encountered. The small sample size did not allow answering the study’s main aim, and was mainly attributed to the study’s protocol complexity. EMG recording failures were attributed to insufficient quality of the EMG signal and detachments of the electrode.

Discussion

The lessons learned from the conduct of this study can be used to design successful future clinical studies.

Conclusions

Adequate participant recruitment, effective EMG recordings, and a careful selection of predictor variables are important ingredients for the successful conduct of a longitudinal clinical study on the association between sleep bruxism and (peri-)implant complications.