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Objectives: This study aimed to assess whether awake bruxism and masticatory muscle activity could be related to external root resorption (ERR) in second molars adjacent to impacted mandibular third molars. Materials and methods: Sixty patients, with requests for a cone-beam, computed tomography, were divided into two groups: ERR (patients with ERR in the second molar, n = 30), and control group (n = 30). Awake bruxism was assessed through the Oral Behaviors Checklist (OBC) and an ecological momentary assessment (EMA). Surface electromyography (EMG) was used to assess the masseter and anterior temporal muscle function. Normality and homogeneity of variances were demonstrated. Descriptive analysis was performed, using the T-test and Chi-square test to compare the characteristics of the groups. A multiple regression model was performed. Results: The ERR group presented more non-functional oral activities related to awake bruxism than the control group, according to OBC (p = 0.027) and EMA (p = 0.035). In addition, the ERR group had higher EMG activity than the control group in rest and isotonic protocols (p < 0.05). Conclusions: Awake bruxism and greater masticatory muscle activity seem to be related to the presence of ERR in second molars adjacent to impacted mandibular third molars. Clinical relevance: The results of the present study can reinforce the theory that triggering ERR in the second molars adjacent to impacted mandibular third molars may be related to mechanical forces coming from the masticatory function. [ABSTRACT FROM AUTHOR]

Background: The noteworthy correlation between bite force and masticatory performance emphasizes its significance as a meaningful and objective method for assessing oral function. Furthermore, in the study of bruxism, the measurement of intraoral bite force assumes critical importance. Given the importance of assessing occlusal forces and bite force, this systematic review aims to assess the efficacy of wireless sensors in measuring these forces. Methods: The search methodology employed in this systematic review adhered to the guidelines outlined by PRISMA. The strategy involved the exploration of various databases, including PubMed/MEDLINE, SCOPUS and SCIELO. An assessment tool was employed to evaluate the bias risk and study quality. Results: This systematic review encompassed six prospective clinical studies involving a total of 89 participants. Wireless sensors for measuring occlusal forces and bite forces were predominantly employed in healthy adults or individuals with bruxism, along with children undergoing orthodontic treatment. All wireless sensors employed in the studies underwent validation and reproducibility assessments, affirming their reliability. The findings indicated that all wireless sensors exhibited efficacy in detecting occlusal forces and bite forces. Conclusion: Wireless sensors offer real‐time monitoring of occlusal and bite forces, aiding in understanding force distribution and identifying bruxism patterns. Despite limited studies on their application, these sensors contribute to evolving insights. Integration into clinical practice requires careful consideration of factors like calibration and patient compliance. Ongoing research is crucial to address limitations and enhance the efficacy of wireless sensors in measuring occlusal and bite forces and managing bruxism. [ABSTRACT FROM AUTHOR]

Background Objectives Methods Results Conclusions Electromyographic activity (EMG) of masticatory muscles during wakefulness is understudied. It is unclear if single channel ambulatory EMG devices are sensitive enough to detect masticatory muscle activity (MMA) during wakefulness.To compare the MMA of various oral tasks recorded with a single channel EMG device ((Grindcare4‐datalogger Prototype device) (GC4‐β)) and a conventional EMG (cEMG) device.EMG activity of 30 standardised oral tasks was recorded unilaterally from the masseter and anterior temporalis muscle in 24 healthy volunteers using GC4‐β and a cEMG device. To compare the EMG data, signal‐to‐noise ratios (SNR) were calculated as a way to normalise EMG activity across tasks. Analysis of variance was used to compare the SNR between the devices, muscles and oral tasks.SNR measured from GC4‐β was overall significantly higher than the cEMG device (p =.001). The SNR for maximum voluntary contraction (MVC) was significantly higher than all other tasks (p <.001). SNR for temporalis with GC4‐β was significantly higher for MVC, hard food, soft food, gum chewing (dominant side), rhythmic clenching and upper lip biting compared to the cEMG device (p <.021). The SNR for masseter with GC4‐β was significantly higher for hard food and gum chewing (dominant side), rhythmic clenching, rhythmic biting of an object and yawning compared to the cEMG device (p <.022).This study provides novel insight into the EMG patterns of numerous oral tasks enhancing knowledge of physiological differences between the masticatory muscles. Further, single channel EMG devices can effectively measure the EMG activity of various oral tasks during wakefulness. [ABSTRACT FROM AUTHOR]

To compare masticatory muscle thickness in patients with temporomandibular disorders (TMDs) during rest and clenching, and by body position, using ultrasonography. This prospective study included 96 patients with TMD (67 females, 29 males; mean age: 40.41 ± 17.88 years): group 1, comprising 66 patients with TMD without bruxism (TMD_nonbruxer), and group 2, comprising 30 patients with concurrent TMD and bruxism (TMD_bruxer). In patients with TMD, bruxism was correlated with the presence of tinnitus, muscle stiffness, sleep problems, psychological stress, and restricted mouth opening. The masseter muscle significantly thickened during clenching (11.16 ± 3.03 mm vs 14.04 ± 3.47 mm, p < 0.001), whereas the temporalis muscle showed no significant increase in thickness from resting to clenching in an upright position (7.91 ± 1.98 vs 8.39 ± 2.08, p = 0.103). Similarly, during clenching in the supine position, the masseter muscle was significantly thicker compared with rest (11.24 ± 2.42 vs 13.49 ± 3.09, p < 0.001), but no significant difference was observed in temporal muscle thickness (8.21 ± 2.16 vs 8.43 ± 1.94, p = 0.464). In comparison between two groups, the average thickness of the masseter muscle was greater among TMD_bruxers than among TMD_nonbruxers in both the upright and supine positions (all p < 0.05). In the generalized lineal model, female sex (B = − 1.018, 95% confidence interval [CI] − 1.855 to − 0.181, p = 0.017) and bruxism (B = 0.868, 95% CI 0.567 to 1.169, p = 0.048) significantly predicted changes in masseter muscle thickness. Female sex (B = − 0.201, 95% CI − 0.299 to − 0.103, p = 0.011), increased age (B = − 0.003, 95% CI − 0.005 to 0.000, p = 0.038), and muscle stiffness (B = − 1.373, 95% CI − 2.369 to − 0.376, p = 0.007) were linked to decreased temporal muscle thickness. Comparing TMD nonbruxer and bruxer muscle thicknesses in upright and supine positions revealed significant increased thickness in the masseter muscle during clenching but not in the temporalis muscle. Masseter muscle thickness varied significantly by sex, body position, and resting/clenching, notably influenced by bruxism. These findings emphasize the relevance of these factors in clinical examinations of patients with TMD. [ABSTRACT FROM AUTHOR]

Background: Masseter muscle activity during wakefulness may be associated with temporomandibular disorder (TMD)‐related symptoms, psychosocial status and pain‐related disability; however, this relationship is unclear. Objectives: This study aimed to determine the relationship between masseter muscle electromyography (EMG) burst/duration during wakefulness and TMD‐related symptoms, psychosocial status and pain‐related disability. Methods: Sixty participants were assessed masseter muscle activity during wakefulness using a data‐logger‐type ultraminiature EMG system and TMD‐related symptoms, psychosocial status and pain‐related disability through Axis I and II of the diagnostic criteria for TMD (DC/TMD). EMG bursts lasting longer than 0.25 s but less than 2.0 s and those lasting longer than 2.0 s were classified as phasic and tonic bursts, respectively. Results: Participants with palpation‐related pain in the temporalis and masseter muscles, as assessed through the DC/TMD examination form in Axis I, had more bursts (number/h) (p =.035 and p =.009, respectively) and longer duration (time/h) (p =.013 and p =.004, respectively) of tonic bursts of the masseter muscle during wakefulness. Participants with palpation‐related pain in the masseter muscles had higher oral behaviour scores during wakefulness using Axis II (p =.001), which affected the number and duration of tonic bursts of the masseter muscle activity during wakefulness (p =.011 and p =.007, respectively). Conclusion: As tonic bursts mainly reflect clenching, individuals with pain in the masseter muscles by palpation may have a high frequency and longer duration of clenching, as well as a high frequency of oral behaviours during wakefulness. [ABSTRACT FROM AUTHOR]

Background: Bruxism is defined as a repetitive jaw‐muscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Bruxism can occur during sleep (sleep bruxism, SB) or during wakefulness (awake bruxism, AB). To date, the effect of AB on the purported negative consequences of bruxism has remained unclear. Objectives: The assessment of AB, its relation to temporomandibular disorders (TMD) treatment modalities, and their possible outcomes were investigated among TMD patients resistant to treatment in primary care and referred to a tertiary care clinic. Methods: The records of 115 patients were studied. Patients were referred to the Head and Neck Centre, Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, for TMD treatment between 2017 and 2020. The data derived from the eligible patients' records included the following: background data (age and sex), referral data (reason and previous treatment), medical background (somatic and psychiatric), clinical and possible radiological diagnoses at a tertiary care clinic, treatment modalities for masticatory muscle myalgia, bruxism assessment, its possible treatment modalities and their outcomes, and overall management outcome. We analysed the outcomes of single treatment modalities and combined groups of modalities. For the demographic data, the Chi‐squared test and Fischer's Exact test were used to determine the associations between the categorical variables. A Sankey‐diagram was used to describe the flow of treatment. Results: Temporomandibular joint‐pain‐dysfunction syndrome (K07.60) was the most frequent single reason to refer a patient to tertiary care (17.4%). At referral, men had myalgia (M79.1) significantly more often (p =.034) than women. Similarly, men had depression (p =.002) more often and other psychiatric diagnoses (p =.034). At tertiary care, the presence of AB was assessed in 53.9%, and self‐reported AB was recorded in 48.7%. In patients with possible AB, those who were prescribed neuropathic pain medication showed significantly less improvement in symptoms (p =.021) than those who underwent splint therapy (p =.009). Overall, half of the patients showed overall improvement in their TMD symptoms from the treatment combinations. Conclusion: Despite several treatment modalities, only half of the patients showed improvement in their symptoms in the present study. A standardised assessment method encompassing all factors contributing to bruxism behaviours and their consequences is suggested. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: With time, due to the poor knowledge on it epidemiology, the need to focus on awake bruxism as a complement of sleep studies emerged. Objective: In line with a similar recent proposal for sleep bruxism (SB), defining clinically oriented research routes to implement knowledge on awake bruxism (AB) metrics is important for an enhanced comprehension of the full bruxism spectrum, that is better assessment and more efficient management. Methods: We summarised current strategies for AB assessment and proposed a research route for improving its metrics. Results: Most of the literature focuses on bruxism in general or SB in particular, whilst knowledge on AB is generally fragmental. Assessment can be based on non‐instrumental or instrumental approaches. The former include self‐report (questionnaires, oral history) and clinical examination, whilst the latter include electromyography (EMG) of jaw muscles during wakefulness as well as the technology‐enhanced ecological momentary assesment (EMA). Phenotyping of different AB activities should be the target of a research task force. In the absence of available data on the frequency and intensity of wake‐time bruxism‐type masticatory muscle activity, any speculation about the identification of thresholds and criteria to identify bruxers is premature. Research routes in the field must focus on the improvement of data reliability and validity. Conclusions: Probing deeper into the study of AB metrics is a fundamental step to assist clinicians in preventing and managing the putative consequences at the individual level. The present manuscript proposes some possible research routes to advance current knowledge. At different levels, instrumentally based and subject‐based information must be gathered in a universally accepted standardised approach. [ABSTRACT FROM AUTHOR]

Background: Bruxism is a masticatory muscle activity occurring during sleep or wakefulness, involving grinding and clenching of teeth and/or jaw bracing. As yet, the aetiology, epidemiology and consequences of awake bruxism (AB) are largely unknown. Objectives: The aims of the study were to AB behaviours using a novel bruxism screener (BruxScreen) questionnaire part and Ecological Momentary Assessment (EMA; BruxApp©) on AB behaviours, and to investigate AB's prevalence among masticatory muscle myalgia patients and non‐patients. Methods: Altogether, 115 participants (masticatory myalgia patients referred to a specialist clinic (n = 67) and non‐patients (n = 46)) filled in a bruxism screener questionnaire to report bruxism behaviours and jaw symptoms. A selection of both groups did a week‐long EMA (patients n = 12, non‐patients n = 11) to report AB behaviours. The chi‐squared test was used to determine group differences in categorical variables. A logistic regression model was fitted to study the probability of AB. Results: According to BruxScreen, bruxism behaviours and jaw symptoms were more frequent in patients than in non‐patients (p <.001). Based on EMA, 14.6% of the behaviour in patients was tooth clenching; for non‐patients, this was 0.5% (p <.000). Relaxed muscles were reported by patients and non‐patients at 20.6% and 56.4%, respectively (p <.021). Logistic regression, adjusted by age and sex, revealed that patients reported AB 5 times more often than non‐patients (OR 4.8, 95% CI 2.1–11.2). Conclusion: Awake bruxism behaviours are significantly more frequent in masticatory muscle myalgia patients than non‐patients and associate with frequent bruxism‐related symptoms. Self‐reported teeth clenching seems to be the most significant sign of AB behaviour. [ABSTRACT FROM AUTHOR]

Background: It is assumed that other factors than masticatory muscle activity awareness could drive the self‐report of awake bruxism. Objectives: To investigate the extent to which the report of awake bruxism is associated with psychological distress, and with the belief that oral behaviours put a strain on the masticatory system among TMD‐pain patients. Materials and Methods: The study sample consisted of 1830 adult patients with reported function‐dependent TMD pain. Awake bruxism was assessed through six items of the Oral Behaviors Checklist. Psychological distress was assessed by means of somatic symptoms, depression and anxiety. Causal attribution belief was measured with the question 'Do you think these behaviours put a strain on your jaws, jaw muscles, and/or teeth?' Results: Mean age of all participants was 42.8 (±15.2) years, 78.2% being female. Controlled for sex, positive, yet weak, correlations were found between awake bruxism and somatic symptom severity (rs = 0.258; p <.001), depression (rs = 0.272; p <.001) and anxiety (rs = 0.314; p <.001): patients with the highest scores reported approximately twice as much awake bruxism compared to those with minimal scores. Controlled for age and sex, a positive, moderate correlation was found between awake bruxism and causal attribution belief (rs = 0.538; p <.001). Patients who believed that performing awake oral behaviours put 'very much' a strain on the masticatory system reported four times more awake bruxism than patients who did not believe that these behaviours are harmful. Conclusions: Based on the results and relevant scientific literature, the theoretical background mechanisms of our findings are discussed in four scenarios that are either in favour of the use of self‐report of awake bruxism being a representation of masticatory muscle activity awareness, or against it. [ABSTRACT FROM AUTHOR]

Background: There is limited knowledge of the possible side‐effects of clear aligners on jaw function. Objectives: To determine the short‐term effect of passive clear aligners (PCAs) on masticatory muscle activity (MMA), occlusal discomfort (OD) and temporomandibular disorder (TMD) symptoms in adults with different levels of self‐reported oral parafunction. Materials and Methods: Participants were screened for oral parafunctional behaviours using the oral behavioural checklist. Respondents in ≥85th and ≤15th percentiles were invited to participate and allocated to a high (HPF: N = 15) or low (lower parafunction [LPF]: N = 16) parafunction group. Participants underwent a TMD clinical examination; somatisation and somatosensory amplification were assessed by questionnaires; OD and stress were assessed by visual analogue scales. While wearing PCAs, awake‐time MMA was assessed three times over 9 days using a wearable electromyography device, along with OD, stress and TMD symptoms. Results: The wearing of PCAs was associated with a significant decrease in mean contraction episode amplitude in both groups (p = 0.003). OD levels increased and remained raised in all participants after insertion of the PCAs (p < 0.001), more so in the HPF group (p = 0.048). The HPF group had higher somatisation scores (p = 0.006) and reported more TMD symptoms at all time points (p ≤ 0.004). No significant changes in stress or TMD symptoms were found in either group during the study period. Conclusions: PCAs were associated with a decrease in MMA in all participants. HPF individuals had greater somatisation and reported greater discomfort when wearing PCAs than LPF individuals. [ABSTRACT FROM AUTHOR]

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

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

Objective. It was aimed to assess the differences in the sensitivities of masticatory and digastric muscles during examination because of continuous and excessive forces in case of bruxism. Material and Method. From the masticatory muscles of 162 individuals with bruxism and 162 control individuals, masseter, temporalis, medial / lateral pterygoideus muscles and digastric muscles were examined. Perceived sense of discomfort-pain during muscle examinations was scored according to a numerical rating scale and recorded as right and left. Results. In individuals with bruxism, the pain scores of the patients for each examined muscle were higher than the control group (p<0.05). In the ROC analysis performed in bruxism, cut-off values for digastric muscle, lateral pterygoideus muscle and other muscles were 2.5, 1.5 and 0.5, respectively. The sensitivity and specificity of the digastric muscles were found to be higher than other muscles (sensitivity: right=72.8%, left=72.8%, specificity: right=18.5%, left=17.9%). Conclusion. Bruxism affects digastric muscles more than masticatory muscles. Digastric muscles and other masticatory muscles should be evaluated in addition to masseter muscle pain, hypertrophy and fatigue in the clinical diagnosis of bruxism. [ABSTRACT FROM AUTHOR]

The neuroanatomical circuitry of jaw muscles has been mostly explored in non‐human animals. A recent rodent study revealed a novel circuit from the central amygdala (CeA) to the trigeminal motor nucleus (5M), which controls biting attacks. This circuit has yet to be delineated in humans. Ultra‐high diffusion‐weighted imaging data from the Human Connectome Project (HCP) allow in vivo delineation of circuits identified in other species—for example, the CeA–5M pathway—in humans. We hypothesized that the CeA–5M circuit could be resolved in humans at both 7 and 3 T. We performed probabilistic tractography between the CeA and 5M in 30 healthy young adults from the HCP database. As a negative control, we performed tractography between the basolateral amygdala (BLAT) and 5M, as CeA is the only amygdalar nucleus with extensive projections to the brainstem. Connectivity strength was operationalized as the number of streamlines between each region of interest. Connectivity strength between CeA–5M and BLAT–5M within each hemisphere was compared, and CeA–5M circuit had significantly stronger connectivity than the BLAT–5M circuit, bilaterally at both 7 T (all p <.001) and 3 T (all p <.001). This study is the first to delineate the CeA–5M circuit in humans. [ABSTRACT FROM AUTHOR]

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

Ultrasound shear wave elastography (SWE) is an emerging modality for the estimation of stiffness, but it has not been studied in relation to common disorders with altered stiffness, such as bruxism, which affects almost one-third of adults. Because this condition could lead to an increased stiffness of masticatory muscles, we investigated SWE in bruxism according to a proof-of-principle and feasibility study with 10 patients with known bruxism and an age- and gender-matched control group. SWE of the left and right masseter muscles was estimated under three conditions: relaxed jaw, 50% of the subjective maximal bite force, and maximal jaw opening. Rejecting the null hypothesis, SWE was significantly increased during relaxed jaw (bruxism 1.92 m/s ± 0.44; controls 1.66 m/s ± 0.24), whereas for maximal mouth opening, the result was vice versa increased with 2.89 m/s ± 0.93 for bruxism patients compared with 3.53 m/s ± 0.95 in the healthy control, which could be due to limited jaw movement in chronic bruxism patients (bruxism 4.46 m/s ± 1.17; controls 5.23 m/s ± 0.43). We show that SWE in bruxism is feasible and could be of potential use for diagnostics and monitoring, though we also highlight important limitations and necessary methodological considerations for future studies. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the influence of the frequency of rhythmic masticatory muscle activity per hour (RMMA/h) scored by polysomnography (PSG) recordings on sleep-related factors and orofacial pain symptoms. According to RMMA/h frequency, participants were assigned either to the control group (i.e., CRMMA, n = 40); or the case group according to high (i.e., HRMMA, n = 12) or low (LRMMA, n = 28) RMMA/h frequency. Fisher's exact (nominal variables), One-way Analysis of Variance followed by post-hoc Tukey (continuous variables) and Poisson Regression tests were used to calculate orofacial pain symptoms and sleep-related breathing, behavior, and architecture differences between controls versus cases at a significance level of 5%. The CRMMA differed from HRMMA and LRMMA subgroups considering orofacial pain, self-reported tooth clenching or grinding, obstructive sleep apnea (OSA), snoring, and most variables considering sleep architecture (P ≤ 0.05). Multivariate adjusted Poisson regression analysis revealed that bruxers, regardless of RMMA/h frequency, presented a significantly higher prevalence rate (PR) related to orofacial pain (PR 1.68; P = 0.025) and self-reported behavior (PR 1.71; P = 0.012). Significant differences in N1, N2 and N3 stages, arousals, arousal per hour, and sleep onset latency variables were found comparing bruxer with high or low RMMA/h frequency. Compared to controls, bruxers presented higher PR related to headache and self-reported tooth clenching or grinding. • Bruxers significantly differed from controls considering headache. • Bruxers significantly differed from controls considering sleep-related factors. • Bruxers presented a higher prevalence ratio related to orofacial pain upon waking. [ABSTRACT FROM AUTHOR]

Background: Bruxism is a repetitive masticatory muscle activity characterized by clenching or grinding of the teeth, or by bracing or thrusting of the mandible, or both. Objectives: To investigate whether bruxism in awake dogs could be associated with brain lesions. Animals: Four dogs with episodic bruxism in the awake state. Methods: Observational retrospective single‐center case series. Inclusion criteria were dogs examined between 2010 and 2021 with episodic bruxism as a presenting complaint or observed during the examination or hospitalization, complete medical records and magnetic resonance imaging or computed tomography of the brain. Bruxism during epileptic seizures as oroalimentary automatism was an exclusion criterion. Results: Four dogs met the inclusion criteria. Two dogs had bruxism while awake as a presenting complaint, whereas in the remaining 2 it was a clinical finding. All dogs had neuroanatomical localization consistent with a forebrain lesion, with diencephalic involvement in 3/4. The diagnostic evaluation was consistent with neoplasia (n = 2) and meningoencephalitis of unknown origin (n = 2), in 1 case accompanied by corpus callosum abnormality affecting the forebrain, in 3 dogs advanced imaging findings were suggestive of increased intracranial pressure. All dogs were euthanized. Conclusions and Clinical Importance: Our results suggest that the presence of bruxism in the awake state associated with other neurological deficits might indicate a forebrain lesion. [ABSTRACT FROM AUTHOR]

The article presents a clarification about the definition of sleep and awake bruxism following the publishing of a consensus paper about bruxism assessment in 2018. Topics discussed include a comparison between sleep and awake bruxism, different motor behaviors that result from different jaw-muscle activities, and the clarification that bruxism is not the disorder but a sign of an associated or co-occurring condition.

Recently, it has been proposed that bruxism could represent an overlearned behavior due to the absence of corticomotor plasticity following a relevant tooth-clenching task (TCT). This study assessed the modulatory effects of a nerve growth factor (NGF) injection on masseter muscle corticomotor excitability, jaw motor performance, pain, and limitation in bruxer and control participants following a TCT. Participants characterized as definitive bruxers or controls were randomly assigned to have injected into the right masseter muscle either NGF or isotonic saline (IS), resulting in a study with 4 arms: IS_Control (n = 7), IS_Bruxer (n = 7); NGF_Control (n = 6), and NGF_Bruxer (n = 8). The primary outcome was the masseter motor evoked potential (MEP) amplitude measured at baseline and after a TCT. After the interventions, significantly higher and lower MEP amplitude and corticomotor map area were observed, respectively, in the IS_Control and NGF_Control groups (P < 0.05). Precision and accuracy depended on the series and target force level with significant between-group differences (P < 0.01). NGF‐induced masseter muscle sensitization, in combination with a training-induced effect, can significantly impact the corticomotor excitability of the masseter muscle in control participants indicating substantial changes in corticomotor excitability, which are not observed in bruxers. These preliminary findings may have therapeuthic implications for the potential to "detrain" and manage bruxism, but further studies with larger sample sizes will be needed to test this new concept. [ABSTRACT FROM AUTHOR]

Objectives: Sleep bruxism (SB) is associated with physiological activities including sympathetic autonomic system dominance and sleep micro-arousal. While oral appliances (OA) are used to prevent SB harmful effects, the influence of OAs physiological mechanisms during sleep is unknown. The aim of this study is to assess whether heart rate variability (HRV) changes, as a marker of autonomic nervous system activity, would be associated with the OA mechanism of action on SB using occlusal splint (OS) and mandibular advancement splint (MAS). Materials and methods: A retrospective analysis, from data previously collected in 21 participants with SB (25.6 ± 4.5 years) with polysomnographic recordings, was done. HRV data were compared between a reference night (no-device) and ones during which OS or MAS was used in a crossover study design. Rhythmic masticatory muscle activity (RMMA) index was compared between nights. HRV was evaluated using autoregressive model analysis for three sections: baseline (distance from RMMA), immediately before, and after RMMA period. Results: A significant reduction in RMMA index, when wearing OA during sleep, was observed (P < 0.01), but was not associated with HRV parameters change. HRV significantly changed after RMMA onset for nights with OA during non-REM sleep in comparison with baseline (P < 0.02). Conclusions: The usage of OAs for SB participants reduced RMMA, but most likely independently of changes in HRV linked to the mechanism associated with SB genesis. Clinical relevance: Wearing OA seems to reduce grinding noise and protect from dental injuries but does not seem to influence SB genesis. [ABSTRACT FROM AUTHOR]

The gold standard for the management of sleep bruxism (SB) is the use of a rigid occlusal splint; however, there are limitations for its use in children and alternatives to the management of SB are needed. Photobiomodulation therapy has been used with positive results in temporomandibular disorders. This study aimed to evaluate the effects of photobiomodulation therapy with infrared LED in children with SB. Thirty children were divided into three groups: Group 1: control/absence of bruxism (n = 10); Group 2: SB treated with infrared LED (n = 10); Group 3: SB treated with occlusal splint (n = 10). Electromyographic evaluation of masseter, anterior temporalis, and upper trapezius, and salivary dopamine levels were assessed before and after treatments. Data were statistically analyzed using two-way mixed model ANOVA. An increase in the temporalis and right masseter EMG activity at rest was observed in Group 3, with large effect size (p < 0.05). Left masseter and temporalis EMG activity did not differ over time in the LED group, similar to the control group. Moreover, the EMG activity of masticatory muscles during chewing and upper trapezius muscle did not differ over time in all groups. The results also pointed to a difference in the levels of dopamine between children with and without SB, with Group 3 showing higher levels in the pre-treatment time compared to controls (p < 0.025). In conclusion, an increase in the masticatory muscles activity at rest was observed in children undergoing splint therapy. Moreover, a difference in the levels of salivary dopamine was found between children with and without SB. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to investigate how emotional information and pain-related information affect the activity of the masticatory muscles in participants with awake bruxism and controls. Material and methods: Different videos and texts, with positive, negative, and neutral valence or related to pain, were presented to a sample of university students, while their electromyographic (EMG) activity around the masseter muscle and their skin conductance were recorded. Two groups were selected, with 24 subjects each: one group of subjects with definitive awake bruxism (confirmed by posterior EMG activity) who also suffered from moderate jaw discomfort, and another group of subjects without bruxism. Results: The results demonstrated that the subjects with definitive awake bruxism displayed greater muscular activity when presented videos and texts with negative valence, especially when related to pain, than the non-bruxist group. Conclusions: This study supports the idea that persons with bruxism who also suffer moderate levels of jaw discomfort present greater bruxism activity when watching pain-related stimuli, and to a lesser extent when watching negative stimuli. Clinical relevance: The increased muscular activity induced by negative and pain-related information might contribute to pain exacerbation and perpetuation in persons with bruxism who suffer from discomfort. [ABSTRACT FROM AUTHOR]

Background: The complex structure of the stomatognathic system plays a vital role in chewing, digestion, speaking, breathing, facial expression and swallowing. Its complexity is the primary reason for creating multidisciplinary teams to manage temporomandibular disorders (TMD). We aimed to assess the masseter stiffness in patients undergoing conservative therapy for masticatory muscle disorders and evaluate the efficacy of manual therapy and stabilization occlusal splint in the treatment of masticatory muscle disorders.Methods: This uncontrolled prospective cohort study included 35 patients with masticatory muscle disorders. The study lasted for eight weeks. The patients were treated with manual therapy and stabilization occlusal splint and evaluated using shear wave elastography of the masseter muscles and patient-reported outcome measures (PROMs) to assess pain, anxiety, quality of sleep, satisfaction with life and perceived stress.Results: After the treatment, the stiffness of both masseter muscles decreased significantly (by 4.21 kPa). The patients reported a significant reduction in pain. At baseline, the median scores ranged from 5 to 8; after treatment, they ranged from 0 to 1 (p < 0.0001). The patients also reported significant improvement in terms of all patient-reported outcome measures. The reduction in stiffness corresponded to the improvement in pain and PROMs, as shown by correlations which were insignificant for all measures.Conclusions: Conservative therapy of masticatory muscle disorders involving manual therapy and stabilization occlusal splint is effective. It reduces the masseter stiffness as objectively shown in shear wave elastography and improves subjective PROMs scores, including numerical pain assessment and selected questionnaires. Shear wave elastography has the potential for broad application in clinical practice to monitor masticatory muscle disorders treatment effects due to its objectivity and non-invasive character. Further research is recommended on larger patient populations and longer follow-up.Trial Registration: The study was registered at clinicaltrials.gov ( NCT03844854 ). First posted date: 19/02/2019. [ABSTRACT FROM AUTHOR]

The article focuses on responding to the significance of accurately diagnosing bruxism based on the established criteria, exploring the ACTN3 genotype's influence on muscle characteristics concerning bruxism diagnosis. Topics include the emphasis on bruxism diagnosis following international consensus, the limitations related to including patients pre-consensus, and the clarification of ACTN3's role in influencing muscle characteristics without directly regulating bruxism's circadian rhythm.

The article focuses on investigating sex-related differences in the lateral pterygoid muscle (LPM) characteristics in patients with anterior disk displacement (ADD), highlighting higher fat infiltration and fibrotic tendencies in female patients compared to males. Topics include the need for clarification regarding the presence of bruxism in the studied patients, that demographic information about bruxism could enhance the understanding of the impact of temporomandibular joint disorders.

[Display omitted] • Sheds new light on the important potential connection between tooth grinding and temporomandibular joint loading • Demonstrates a larger effect of grinding inclination than grinding position on TMJ loading • Creates a novel computer simulation of TMJ disc stress during dynamic tooth grinding tasks • Uses state-of-the-art in silico methods for a highly multidisciplinary investigation, which is not feasible in vivo • Presents a tracking simulation approach to work around the highly complicated recording of masticatory muscle EMG acquisition Functional impairment of the masticatory region can have significant consequences that range from a loss of quality of life to severe health issues. Increased temporomandibular joint loading is often connected with temporomandibular disorders, but the effect of morphological factors on joint loading is a heavily discussed topic. Due to the small size and complex structure of the masticatory region in vivo investigations of these connections are difficult to perform. We propose a novel in silico approach for the investigation of the effect of wear facet inclination and position on TMJ stress. We use a forward-dynamics tracking approach to simulate lateral bruxing on the canine and first molar using 6 different inclinations, resulting in a total of 12 simulated cases. By using a computational model, we control a single variable without interfering with the system. Muscle activation pattern, maximum bruxing force as well as TMJ disc stress are reported for all simulations. Muscle activation patterns and bruxing forces agree well with previously reported EMG findings and in vivo force measurements. The simulation results show that an increase in inclination leads to a decrease in TMJ loading. Wear facet position seems to play a smaller role with regard to bruxing force but might be more relevant for TMJ loading. Together these results suggest a possible effect of tooth morphology on TMJ loading during bruxism. [ABSTRACT FROM AUTHOR]

Background: Little is known about wake‐time masseter activity of patients with masticatory muscle pain in real‐life settings. Objectives: The aims of this study were (1) to assess wake‐time masseter activity of women with masticatory muscle pain (MMP) and compare it with that of pain‐free women; and (2) to investigate the association between objectively measured masseter contractions and self‐reported oral behaviours. Methods: Adult women (N = 27) diagnosed with MMP were age‐matched with pain‐free women (N = 26). The electromyographic (EMG) activity of the masseter muscle when awake was recorded unilaterally for two consecutive days. The number of contraction episodes and relative contraction time (%) were calculated using cut‐off thresholds of 3%, 5% and 10% of maximum voluntary contraction (MVC). Self‐reported daytime oral activity was assessed using the Oral Behaviours Checklist (OBC, items 3–21). Data were analysed using univariate tests and mixed‐model analyses. Results: The number of contraction episodes was similar between groups for all detection thresholds, but the relative contraction time at the lower detection thresholds (i.e. 3% MVC and 5% MVC) was significantly longer (1.5‐fold) in the MMP than in the pain‐free group. The OBC scores were significantly higher in the women with MMP than in controls, but no positive association could be found between EMG variables and OBC scores. Conclusion: Women with MMP engage in low‐level masseter muscle contractions, which last longer than those of pain‐free controls. There was no relationship between self‐reported oral behaviours and masseter activity when awake. These findings support the notion that prolonged low‐level clenching when awake may play a role in the pathophysiology of MMP. [ABSTRACT FROM AUTHOR]

A smartphone‐based ecological momentary assessment (EMA) strategy was used to assess the frequency of awake bruxism behaviours, based on the report of five oral conditions (ie relaxed jaw muscles, teeth contact, mandible bracing, teeth clenching and teeth grinding). One hundred and fifty‐three (N = 153) healthy young adults (mean ± SD age = 22.9 ± 3.2 years), recruited in two different Italian Universities, used a dedicated smartphone application that sent 20 alerts/day at random times for seven days. Upon alert receipt, the subjects had to report in real‐time one of the above five possible oral conditions. Individual data were used to calculate an average frequency of the study population for each day. For each condition, a coefficient of variation (CV) of frequency data was calculated as the ratio between SD and mean values over the seven recording days. Average frequency of the different behaviours over the seven days was as follows: relaxed jaw muscle, 76.4%; teeth contact, 13.6%; mandible bracing, 7.0%; teeth clenching, 2.5%; and teeth grinding, 0.5%. No significant differences were found in frequency data between the two University samples. The relaxed jaw muscles condition was more frequent in males (80.7 ± 17.7) than in females (73.4 ± 22.2). The frequency of relaxed jaw muscles condition over the period of observation had a very low coefficient of variation (0.27), while for the different awake bruxism behaviours, CV was in a range between 1.5 (teeth contact) and 4.3 (teeth grinding). Teeth contact was the most prevalent behaviour (57.5–69.7). Findings from this investigation suggest that the average frequency of AB behaviours over one week, investigated using EMA‐approach, is around 23.6%. [ABSTRACT FROM AUTHOR]

Objectives: Trait anxiety is associated with an increased occurrence of awake bruxism episodes, a behavior characterized by clenching of the teeth contributing to temporomandibular disorders in some individuals. Here we measured the activity of the masseter and the intensity and duration of spontaneous wake-time tooth clenching episodes in healthy individuals with different levels of trait anxiety (TA). Materials and methods: Two hundred fifty-five individuals completed a web survey. Using their TA scores, we allocated them in low (< 20th percentile of the TA score distribution), intermediate (between 20th and 80th), and high (> 80th) TA groups. We analyzed the electromyographic (EMG) activity of the right masseter during a 15-min silent reading task in forty-three individuals with low (n = 12), intermediate (n = 17), and high TA (n = 14). We tested between-group differences in EMG activity of the masseter, as well as postural activity—the muscular activity that maintains mandibular posture, and amplitude and duration of spontaneous tooth clenching episodes. Results: The activity of the masseter (mean ± SEM %maximum voluntary contraction/MVC) was greater in the high TA (10.23 ± 0.16%MVC) than the intermediate (8.49 ± 0.16%MVC) and low (7.97 ± 0.22%MVC) TA groups (all p < 0.001). Postural activity did not differ between groups (all p > 0.05). The EMG amplitude of tooth clenching episodes was greater in the high TA (19.97 ± 0.21 %MVC) than the intermediate (16.40 ± 0.24%MVC) and low (15.48 ± 0.38 %MVC) TA groups (all p < 0.05). The cumulative duration of clenching episodes was not different between groups (p = 0.390). Conclusions: Increased TA is associated with both increased masseter muscle activity and intensity of wake-time tooth clenching episodes. Clinical relevance: TA may contribute significantly to masticatory muscle overload. [ABSTRACT FROM AUTHOR]

The number of drug addicts in the world is growing every year. The aim of the study was to assess the dental status of drug-addicted patients with parafunction of the dental-jaw apparatus. We used clinical, analytical, functional and histological research methods. 119 drug-addicted and 110 non-drug-dependent patients aged 18 to 54 were examined. In order to confirm the presence of parafunctions of the dental-jaw apparatus in patients, we conducted an occludogram study, as well as an assessment of the index of parafunctions of the masticatory muscles and the degree of their severity. The structure of tooth tissues was examined by histological method. Examination of drug-addicted patients revealed the presence of numerous carious cavities, secondary adentia, enamel erosion, pathological abrasion, signs of gingivitis and periodontitis, tooth chipping. The prevalence of parafunction of the dental-jaw apparatus, in particular bruxism, in drug-addicted patients is 1.56 times higher than this figure among non-drug addicts. The results of the occludogram and the index of parafunctions of the masticatory muscles differ significantly between the study groups. The mean value of the masticatory muscle parafunction index among drug-addicted patients is 2.06 times significantly higher than the value among non-drug-addicted men and 2.03 times higher among women. Histological examination of the tooth tissues of drug-addicted patients indicates a disorder of the mineralization of both enamel and dentin. Thinning of the peripheral zone of the pulp, which is normally represented by a layer of odontoblasts, which provide regeneration and nutrition of dentin, is more common in persons under 25 years of age. Drug use adversely affects the dental status of patients and the condition of the hard tissues of the tooth. [ABSTRACT FROM AUTHOR]

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 (EMGposture), and to produce spontaneous awake bruxism episodes (EMGbruxism), 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, EMGposture 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], EMGposture 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. EMGposture 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. EMGbruxism 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], EMGbruxism 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]. EMGbruxism 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. [ABSTRACT FROM AUTHOR]

Introduction: Bad habits often found in children such as bruxism may have a profound effect on the health of teeth, periodontium, masticatory muscles and TMJ temporomandibular joints. Excessive masticatory muscle activity can result in disruption of local blood flow and micro circulation, and the pain due to ischemia, bruxism increases excessive strength resulting in an abnormal burden on the mastication system causing changes in some elements of the stomatognathic system resulting in an imbalance that causes stomatognathic system dysfunction. Objective: To review the relationship between bruxism and temporomandibular disorders. Method: Scientific evidence and clinical cases taken from the literature to support this review and information about the relationship of bruxism with temporomandibular disorders (TMD) in children is collected. Results/Discussion: There were several relationships of bruxism with temporomandibular disorders such as joint sounds, myalgia and temporomandibular pain. Conclusion: Brusixm in children is usually influenced by psychological factors such as stress or excessive anxiety. Parafunctional habits such as bruxismn will produce excessive strength so that abnormal loads in the mastication system cause changes in some elements of the stomatognathic system, causing an imbalance that causes stomatognathic system dysfunction such as TMJ pain, joints and myalgia. [ABSTRACT FROM AUTHOR]

Background: It is important to know how easy or difficult it is to use an ambulatory electromyographic (EMG) device for sleep bruxism assessment, and how this might affect its future utilisation. Objective: To explore the experience of individuals using an EMG device that pairs with a smartphone app, in order to detect factors that could facilitate and/or hamper its utilisation in future scientific research. Methods: Fifteen adults were recruited in the Orofacial Pain and Dysfunction Clinic of the Academic Centre for Dentistry Amsterdam (ACTA). Overnight recordings were performed in the home setting during one week. Time investment, feelings and thoughts, encountered difficulties and reasons for not using the device were assessed in a diary through open‐ended questions and 5‐point Likert scales. Content analysis of textual data was performed, and descriptives of quantitative data were calculated. Results: Time investment was low (mean 10.2 minutes in the clinic, and 1.9 minutes per recording at home). Quantitative data showed an overall good experience (median of 4). Qualitative diary data showed that the desire to gain insight into one's masticatory muscle activity formed the main motivation to use the device. Device detachment and difficulty in using the app were the most prominent negative experiences. Conclusion: The EMG device was well accepted for multiple overnight recordings. Curiosity for gaining insight into muscle activity was the most important factor that facilitated its use, and the app addressed this need. Device detachment and difficulties in using the app were the main factors that hampered its use. [ABSTRACT FROM AUTHOR]

Study Objectives: The coexistence of sleep-related breathing disorders (SRBD) and sleep bruxism (SB) is often mentioned in the literature. Polysomnography (PSG) with video recording gives the best opportunity to identify both of these phenomena. This study aimed to evaluate the relationship between SRBD and SB.Methods: Patients from the Clinic of Prosthetic Dentistry operating at Wroclaw Medical University with diagnosed probable SB were subjected to one-night video-polysomnography. PSGs were evaluated according to standard sleep criteria. The results of the examination were analyzed for the occurrence of SB and SRBD. The Bruxism Episodes Index (BEI) and the types of electromyographical pathways (phasic, tonic, mixed) were used to evaluate SB. The Apnea/Hypopnea Index (AHI) and Oxygen Desaturation Index (ODI) were used to assess respiratory events. Subjects were divided into two groups according to SB occurrence: the studied group (bruxers, BEI ≥ 2) and control group (non-bruxers, BEI < 2).Results: Quantitative analysis showed a lack of a statistically significant relationship between BEI and AHI (p = 0.82) and ODI (p = 0.90) in the studied group and controls. Qualitative analysis showed that the increase in both AHI and ODI was statistically significantly correlated with the increase in the number of tonic types of electromyographical pathways (p = 0.047, p = 0.006, respectively).Conclusions: This study showed a significant relationship between tonic electromyographic pathways in SB episodes and SRBD. Tonic muscle contractions can be cause and effect for the formation of respiratory events. The occurrence of tonic episodes may be the key to understanding the causal relationship between SB and SRBD and should be more precisely examined.Clinical Trial: Evaluation of Selected Disorders with Sleep Bruxism, www.ClinicalTrials.gov, identifier NCT03083405. [ABSTRACT FROM AUTHOR]

Background: Studies have shown co‐contraction of jaw and neck muscles in healthy subjects during (sub) maximum voluntary jaw clenching, indicating functional inter‐relation between these muscles during awake bruxism. So far, coherence of jaw and neck muscles has not been evaluated during either awake or sleep bruxism. Objective: The objective of this study was to evaluate the coherence between jaw and neck muscle activity during sleep bruxism. Methods: In a cross‐sectional observational design, the electromyographic activity of jaw (masseter, temporalis) and neck (sternocleidomastoid, trapezius) muscles in individuals with "definite" sleep bruxism was measured using ambulatory polysomnography (PSG). Coherence for masseter‐temporalis, masseter‐sternocleidomastoid and masseter‐trapezius was measured during phasic and mixed rhythmic masticatory muscle activity episodes using coherence‐analysing software. Outcome measures were as follows: presence or absence of significant coherence per episode (in percentages), frequency of peak coherence (FPC) per episode and sleep stage. Results: A total of 632 episodes within 16 PSGs of eight individuals were analysed. Significant coherence was found between the jaw and neck muscles in 84.9% of the episodes. FPCs of masseter‐temporalis were significantly positively correlated with those of masseter‐sternocleidomastoid or masseter‐trapezius (P <.001). Sleep stages did not significantly influence coherence of these muscular couples. Conclusion: During sleep bruxism, jaw and neck muscle activation is significantly coherent. Coherence occurs independently of sleep stage. These results support the hypothesis of bruxism being a centrally regulated phenomenon. [ABSTRACT FROM AUTHOR]

Objective: This study aims to verify the associations among sleep bruxism (SB), sleep arousal (SA) and concurrent body movements. Material and Methods: Subjects underwent a standard overnight polysomnography test and audio‐video recordings. Sleep quality was evaluated according to the Rechtschaffen and Kales criteria, while SA was determined as per the American Sleep Disorders Association criteria. Analyses were performed by an external institution after masking of the subjects' information. SB was assessed based on the presence/absence of rhythmic masticatory muscle activity (RMMA) episodes, which were identified by using electromyography of the masseter muscle. The observed simultaneous movements included lower leg movement (LLM), swallowing, face scratching, head movement, body movement, eye blinking, coughing, licking, sighing, body scratching, lip sucking, somniloquy and yawning. The LLM was determined visually, as well as through an increase in the tibialis electromyogram signal. Other movements were visually assessed using audio‐video recordings. The incidences of all the simultaneous movements were compared between RMMA with intercurrent SA (SAwRMMA; RMMA episode derived from a masseter electromyogram showing more than 10% of maximum voluntary contraction) and SA without RMMA (SAw/oRMMA). Results: Fourteen subjects were included in this study (females/males: 4/10, mean age: 31.5 ± 5.7 years). Among these, LLM, swallowing, body movement, licking, body scratching and lip sucking were frequently observed in SAwRMMA episodes than in SAw/oRMMA episodes, significantly. However, the non‐specific simultaneous movements were higher observed in SAw/oRMMA episodes than that in SAwRMMA. Conclusion: Our results suggest that SB is concurrently activated with LLM in relation to arousal. [ABSTRACT FROM AUTHOR]

Objective: To systematize evidence on the efficacy of botulinum toxin type A (BTA) in the treatment of bruxism measured through bite force or electromyography (EMG) at the masseter muscle. Method: Identification of relevant articles through databases PubMed, Web of Science, SCOPUS, Ovid and EBSCO and manual search were performed for sources from review articles. Studies scoring less than 3 on the Jadad Scale were excluded. Results: Four articles were included after an exclusion of 333 articles. 3 articles measured EMG and 1 bite force. 1 article did not record a significant drop of activity, 1 article recorded reduction midway and at final endpoint. 2 articles recorded initial reduction, but a non significant difference at later follow up. Conclusion: The available research is inconclusive and does not show enough evidence that bruxism can be treated with BTA injections. However, promising results have been shown in individual studies and further research in this area is needed. [ABSTRACT FROM AUTHOR]

Most sleep bruxism (SB) episodes are accompanied by an increase in sympathetic tone and heart rate (HR). To characterise heart rate (HR) changes in relation to rhythmic masticatory muscle activities (RMMAs) in SB patients, polysomnographic recordings were performed on 10 SB patients and 11 normal controls. The duration of movement events, amplitude and duration of HR increases, and time to reach HR peak associated with RMMAs and limb movements (LMs) were determined, and the relationships of the parameters of HR increases with types of movements and RMMAs were analysed. All of the parameters of HR increases associated with three types of movements (RMMAs, RMMAs + LMs and LMs) and masseter activities (phasic, tonic and mixed) were significantly different (two‐way ANOVA, P <.001 for all) in both SB patients and controls. The duration of RMMAs/LMs was positively correlated with the parameters (SB patients: R2 =.24‐.85, P <.0001; controls: R2 =.23‐.68, P <.0001). The amplitude of HR increases was also positively correlated with respiration changes in the SB patients (R2 =.3258, P <.0001) and controls (R2 =.09469, P <.05). The proportions of phasic RMMAs associated with awakenings, microarousals and no cortical arousals were significantly different and so were the proportions of tonic and mixed RMMAs (Friedman's tests, P <.05‐.001). The HR increases associated with RMMAs may be intrinsic to the cortical arousal response and autonomic activation, and differences in HR increases associated with different types of movements and RMMAs might be related to the changes in respiration and differences in cortical arousal levels. [ABSTRACT FROM AUTHOR]

The aim of the present study was to perform a critical reflection about intervention options for bruxism reduction in children and adolescents. Search was conducted based on the PICO-structured question: "What are the intervention options to reduce bruxism in children/adolescents?". No language, year, or study design restrictions were imposed. Studies reporting interventions to reduce bruxism in children (< 10) and adolescents (10 to 19 years old) were included. Reviews and letters to editors were not included. From 2723 records, 17 papers were included. Included studies were primarily randomized clinical trials performed in Brazil (35.3%) and using different criteria for the diagnosis of bruxism. Reduction in self-reported bruxism and headaches associated with bruxism were observed in studies that used medications (hydroxyzine/trazodone/flurazepam), occlusal splints, orthodontic interventions, and psychological and physical therapy interventions. Reduction in Rhythmic Masticatory Muscle Activity was observed with the use of the occlusal splint and in orthodontic interventions. Alternative treatments (medicinal extracts such as Melissa officinalis-L) have shown inconclusive results.Conclusions: Several intervention options are available to inhibit or reduce bruxism activity. The respective indication, contraindications, and side effects of each treatment option must be assessed individually and carefully, taking into account that bruxism is not considered a disorder in otherwise healthy individuals.What is known• Biological and psychological factors have been strongly correlated to the development of bruxism• Bruxism prevalence ranging from 6 to 50% in childrenWhat is new• Reduction in self-reported bruxism and headaches associated with bruxism were observed in studies that used medication (Hydroxyzine/ Trazodone/ Flurazepam), occlusal splints, orthodontic interventions, psychological, and physical therapy interventions• A reduction in Rhythmic Masticatory Muscle Activity was observed with the use of the occlusal splint and orthodontic interventions. Alternative treatments (medicinal extracts such as Melissa officinalis L) show inconclusive results in respect of the reduction in bruxism. [ABSTRACT FROM AUTHOR]

Objectives: To characterize eye movements during rhythmic masticatory muscle activities (RMMAs) in patients with sleep bruxism (SB).Methods: Polysomnographic (PSG) recordings were performed on SB patients and normal controls during sleep (n = 8 for each group) and wakefulness (n = 9 for each group). The eye movements associated with episodes of RMMAs/SB during sleep and jaw movements during wakefulness were analyzed.Results: During sleep, all episodes of RMMAs/SB in the SB patients and controls were associated with eye movements and most of the RMMAs/SB related slow eye movements (SB patients: 96.29%, 1583/1644; Controls: 97.49%, 543/557) were horizontal in the SB patients and controls. During wakefulness, all of the series of jaw movements were associated with eye movements. Most of cycles of jaw movements (SB patients: 88.89%, 200/225; Controls: 95.11%, 214/225) were associated with slow eye movements and most of the eye movements (SB patients: 52.50%, 105/200; Controls: 61.21%, 131/214) were vertical. There were significant correlations between the durations of episodes of eye movements and RMMAs/SB during sleep and between the duration of episodes of eye movements and duration of series of jaw movements during wakefulness in the SB patients and controls.Conclusions: Most of RMMAs/SB episodes during sleep and jaw movements during wakefulness are associated with eye movements in SB patients and normal controls. [ABSTRACT FROM AUTHOR]

This commentary discusses the need to move on from the adoption of cut‐off points for the definition of the presence/absence of bruxism and justifies the need to embrace an evaluation based on the continuum of jaw motor behaviours. Currently, the number of events per hour, as identified by polysomnography (PSG), is used to define the presence of sleep bruxism (SB). Whilst PSG still remains the indispensable equipment to study the neurophysiological correlates of SB, the scoring criteria based on a cut‐off point are of questionable clinical usefulness for the study of oral health outcomes. For awake bruxism (AB), criteria for a definite diagnosis have never been proposed. Some goal‐oriented strategies are proposed to identify bruxism behaviours that increase the risk of negative oral health outcomes (eg, tooth wear, muscle and/or temporomandibular joint [TMJ] pain, restorative complications). One possible strategy would embrace an improved knowledge on the epidemiology and natural variability of bruxism, even including study of the amount of PSG/SB and electromyography masticatory muscle activity (EMG/MMA) during sleep and the frequency/prevalence of bruxism behaviours during wakefulness that are needed to represent a risk factor for clinical consequences, if any. There should not be any preclusion about the diagnostic strategies to pursue that goal, and a combination of instrumental and non‐instrumental approaches may even emerge as the best available option. Once data are available, large‐scale, non‐selected population samples representing the entire continuum of EMG/MMA activities are also needed, in the attempt to estimate untreated health risks in the population. [ABSTRACT FROM AUTHOR]

Introduction: High-performance athletes develop an increased muscular mass, including the masticatory muscles. They tend to contract more often and with a higher intensity, which may lead to bruxism. The current study aims to analyse the incidence of bruxism throughout a Romanian group of high-performance athletes in kayak and canoe and to establish how the type of sport and training characteristics influence the tooth damage. Materials and methods: 34 high performance athletes in kayak and canoe were examined clinically and auxiliary data was collected with a questionnaire, during a sporting event in April, 2018. Data was collected regarding their dental status, facial symmetry, TMJ symptoms and training characteristics. Results and discussions: All subjects showed an increased prevalence of bruxing activity. A strong correlation between the type of performed sport and the distribution of the dental pathology was observed, with kayak athletes showing a symmetrical tooth wear, while canoe paddlers presented dental lesions predominantly on the active side of paddling. An increased prevalence of complaints related to bruxism during training and in the morning was observed. The number of years of high-performance training and the number of hours spent training during a day had an important impact on the degree of tooth wear. 91.3% of the kayak athletes displayed a symmetrical hypertrophy of the masseter muscles, while 90.9% of canoe paddlers had a unilateral hypertrophy, which coincided with the active side of the rowing. Conclusions: High performance athletes are predisposed to bruxism. The type of sport influences the distribution of tooth damage. The amount of training hours and the number of years spent practicing high-performance sport is strongly correlated with the degree of tooth wear. Although kayak and canoe are not full contact sports, the athletes should wear a sports guard both during the night and during training. [ABSTRACT FROM AUTHOR]

Objectives: To test a smartphone-assisted wireless device for assessing electromyographic (EMG) activity of the masseter muscle in freely moving individuals undertaking routine activities. Materials and Methods: EMG activity was detected unilaterally from the masseter muscle in 12 volunteers using surface electrodes connected to both a smartphone-assisted wireless EMG device and a fixed-wired EMG equipment (reference standard). After performing a series of standardized tasks in the laboratory, participants wore the wireless device for 8 h while performing their normal routine. Results: The wireless device reliably detected masseter muscle contraction episodes under both laboratory and natural environment conditions. The intraclass correlation coefficients for the muscle contraction episode amplitude and duration detected by the wireless and the wired equipment ranged from 0.94–1.00 to 0.82–1.00, respectively. Most masseter contraction episodes during normal routine were of low amplitude (< 10% MVC) and short duration (< 10 s), with no significant differences between sexes or facial side. Conclusions: Within the limitations of the study, smartphone-assisted monitoring of the jaw muscles represents a promising tool to investigate oral behavior patterns in free moving individuals. Clinical relevance: Smartphone-assisted monitoring of masticatory muscle activity may enable possible associations between excessive muscle activity, bruxism, dysfunction, and pain to be investigated, and managed via biofeedback. [ABSTRACT FROM AUTHOR]

Summary: Background: Most rhythmic masticatory muscle activities (RMMAs) have been shown to be accompanied with limb movements (LMs) in sleep bruxism (SB) patients during sleep. Objectives: To compare the relationships between RMMAs and LMs in SB patients and normal subjects. Methods: Polysomnographic recordings were performed on eight SB patients and nine normal subjects and the frequencies and durations of RMMAs as well as LMs were determined. Linear regression and correlation analysis were performed to study the relationship between durations of RMMAs and LMs when RMMAs occurred with LMs. Results: Most LMs in SB patients, but not in normal subjects, were accompanied with RMMAs. RMMAs in SB patients were more likely to be isolated, phasic or mixed, while RMMAs in normal subjects were more likely to be tonic. The frequencies of LMs, isolated RMMAs and RMMAs accompanied with LMs in SB patients were significantly higher than those in normal subjects. Furthermore, linear regression and correlation analysis showed that duration of RMMAs was significantly associated with that of LMs when RMMAs occurred with LMs. The duration of RMMAs, when accompanied with LMs, in SB patients was significantly longer than that in normal subjects. Conclusions: Close relationships between LMs and RMMAs exist in SB patients and normal subjects, and SB episodes may be part of cortical arousal responses and the increased cortical activities associated with SB episodes may not just be localised to the central nervous system (CNS) that controls jaw movements but may also include other parts of CNS that controls LMs. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this cross-sectional study was to assess the psychological status of patients with bruxism and to explore the potential relationship between psychological status and rhythmic masticatory muscle activity (RMMA), since the basic manifestation of sleep bruxism is RMMA.Methods: Twenty-five patients (nine males, 16 females, and mean age 27.84 ± 5.60) who self-reported having SB and 25 normal subjects were randomly recruited. Fifty subjects filled out the Symptom Checklist-90 (SCL-90) to assess their psychopathological status. SB was diagnosed by polysomnography (PSG), and RMMA was recorded based on the results of PSG.Results: In this study we detected 15.89 ± 4.23 RMMA episodes per hour in normal subjects, whereas 41.23 ± 16.78 RMMA episodes per hour were recorded in patients with SB, which was nearly three times of the former group with statistical significance (P = 0.001). Paired t-test revealed significant differences between SB patients and normal subjects in any of the SCL-90 subscales (P = 0.001). Regarding total psychopathological scores, 10 of the 25 SB patients endorsed scores higher than 160, and the positive rate was 40%. In addition, obsessive-compulsive behavior, interpersonal sensitivity, depression, anxiety, paranoid ideation and psychoticism were all statistically associated with RMMA (P < 0.05).Conclusion: Within the limitations of the study, we found that patients with sleep bruxism tend to have poor psychological status, and obsessive-compulsive behavior, interpersonal sensitivity, depression, anxiety, paranoid ideation and psychoticism are related to onset of SB. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Tardive dystonia is a risk factor in medical antipsychotic treatment. It often begins with repetitive involuntary jaw and tongue movements resulting in impaired chewing and detrimental effect on the dentition. The orofacial dysfunction may go unrecognized in a neurological setting. The diagnosis may be difficult so we suggest interdisciplinary collaboration. Tardive dystonia is a risk factor in medical antipsychotic treatment. It often begins with repetitive involuntary jaw and tongue movements resulting in impaired chewing and detrimental effect on the dentition. The orofacial dysfunction may go unrecognized in a neurological setting. The diagnosis may be difficult so we suggest interdisciplinary collaboration. [ABSTRACT FROM AUTHOR]

Summary: Background: Sleep bruxism is a phenomenon associated with masticatory muscle hyperactivity. While stretching of limb and trunk muscles has been extensively studied for musculoskeletal disorders, little is known about the effectiveness of stretching of masticatory muscles in the management of bruxism. Objective: The aim of this study is to determine the effectiveness of stretching of the masticatory muscles for sleep bruxism. Methods: Twenty four pain‐free individuals with sleep bruxism were randomly assigned to either an intervention group or a control group. Both groups were given sleep hygiene advice and the intervention group additionally received muscle‐stretching exercises for 10 days. Primary outcome measures, bruxism bursts and episodes per hour of sleep, were measured by ambulant polysomnography. Secondary outcome measures were among others pain‐free active maximum mouth opening (MMO) and masseter pressure pain threshold (PPT). Results: The number of bruxism episodes per hour of sleep increased more in the intervention group than in the control group (by 1.1 episodes, P = 0.066), as did the number of bruxism bursts per hour of sleep (by 8.6 bursts, P = 0.049). MMO and PPT increased significantly more in the intervention group (by 3.2 mm, P = 0.020; and by 1.0 kg/cm2, P = 0.036, respectively). Conclusion: Static stretching of the masticatory muscles resulted in a minor increase in sleep bruxism episodes (not significant) and bursts (significant). It also led to a significant increase in MMO and PPT. Therefore, masticatory muscle stretching was not effective in reducing sleep bruxism in the absence of pain and/or dysfunction. [ABSTRACT FROM AUTHOR]