Oro-facial pain experience among symphony orchestra musicians in Finland is associated with reported stress, sleep bruxism and disrupted sleep-Independent of the instrument group

BACKGROUND

To evaluate whether oro-facial pain experience was related to the type of musical instrument and to learn more about the roles of sleep and sleep-related issues in the pain among professional musicians.

OBJECTIVES

A standard questionnaire was sent to all Finnish symphony orchestras (n = 19), with altogether 1005 professional musicians and other personnel.

METHODS

The questionnaire covered descriptive data, instrument group, items on perceived quality of sleep, possible sleep bruxism, stress experience and oro-facial pain experience during the past 30 days.

RESULTS

In the present study, which included the musicians only, the response rate was 58.7% (n = 488). All orchestras participated in the study, and there was no significant difference in the response rate between the orchestras. The mean age of men (52.3%) was 47.7 (SD 10.3) and of women (47.7%) was 43.4 (SD 9.8) years (P < 0.001). Overall, current pain in the oro-facial area was reported by 28.9%, frequent bruxism by 12.1% and frequent stress by 20.8%. According to Somers' d, there were statistically significant but moderate correlations between overall pain reports in the oro-facial area and disrupted sleep (d = 0.127, P = 0.001), sleep bruxism (d = 0.241, P < 0.001) and stress experiences (d = 0.193, P < 0.001). Logistic regression revealed, independent of the instrument group (string, woodwind, brass wind, percussion), that current oro-facial pain experience was significantly associated with disrupted sleep (P = 0.001), frequent sleep bruxism (P < 0.001) and frequent stress (P = 0.002) experiences.

CONCLUSIONS

Among symphony orchestra musicians, oro-facial pain experience seems to be related to perceptions of stress, sleep bruxism and disrupted sleep rather than the instrument group.

Evaluation of Relationship Between Sleep Bruxism and Headache Impact Test-6 (HIT-6) Scores: A Polysomnographic Study

Sleep bruxism (SB) is a masticatory muscle activity during sleep characterized by teeth clenching or grinding and/or bracing or thrusting of the mandible. Morning headache is considered as a common symptom of SB; however, the relationship between SB and headache and its impact on patient's life is not clear. Therefore, the present study aimed to assess the relationship between SB using polysomnography with video/audio recording and Headache Impact Test-6 (HIT-6) scores. SB was evaluated in respondents by single-night diagnostic polysomnography with video/audio recording. The study found that Bruxism Episode Index was similar in the group with significant impact of headache on patient's life (HIT-6 score ≥ 50) and in group with little or no impact (HIT-6 score < 50). A statistically significant positive correlation was observed between bruxism associated with arousal and HIT-6 score (r = 0.51, p < 0.05) and between mixed bruxism and HIT-6 score (r = 0.58, p < 0.05) in the subgroup with phasic bruxism. The results indicated the relationship between SB and impact of severity of headache on the patient's life measured by HIT-6 is only modest. It was also found that the impact of severity of headache measured by HIT-6 is altered only in those with phasic bruxism and is associated with arousal. Further research should elucidate the factors influencing the relationship between SB and headache.

Trial Registration: Clinical Trials NCT03083405, WMU1/2017, https://clinicaltrials.gov/ct2/show/NCT03083405

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Awake and Sleep Bruxism Among Israeli Adolescents

Introduction: Sleep and awake bruxism are potential risk factors for oral hard tissue damage, failure of dental restorations and/or temporomandibular disorders. Identifying the determinants of sleep and awake bruxism among adolescents will enable development of preventive interventions for those at risk.

Objectives: To determine emotional, behavioral and physiological associations of sleep and awake bruxism among Israeli adolescents.

Methods: Two thousand nine hundred ninety-three Israeli high school students, from five different high schools in Israel, were approached in the classroom and requested to complete online questionnaires on sleep and awake bruxism, emotional aspects, smoking, alcohol consumption, oral habits, facial pain, and masticatory disturbances. The final study sample concerning awake and sleep bruxism included 2,347 participants.

Results: 1,019 (43.4%) participants reported not experiencing any form of bruxism (neither sleep nor awake), 809 (34.5%) reported awake bruxism, 348 (14.8%) reported sleep bruxism and 171 (7.3%) reported both sleep and awake bruxism. Multivariate analyses (Generalized Linear Model with a binary logistic dependent variable) showed that one of the prominent variables affecting the occurrence of sleep bruxism was anxiety (mild, moderate and severe anxiety, Odds Ratios (OR) of 1.38, 2.08, and 2.35, respectively). Other variables associated with sleep bruxism were stress (each point in the stress scale increased the risk of SB by 3.2%), temporomandibular symptoms (OR = 2.17) and chewing difficulties (OR = 2.35). Neck pain showed a negative association (OR = 0.086). Multivariate analyses for awake bruxism showed an effect of moderate anxiety (OR = 1.6). Other variables associated with awake bruxism were stress (each point in stress scale increased the risk of AB by 3.3%), high and low levels of facial pain (OR = 2.94 and 1.53, respectively), creaks (OR = 1.85) and oral habits (OR = 1.36). Sleep bruxism was found to be a predictor for awake bruxism, and vice versa. In both cases ORs were 8.14.

Conclusions: Among adolescents, sleep and awake bruxism are associated with emotional aspects as well as with facial pain symptoms and/or masticatory system disturbances. Awareness is recommended to decrease potential risks to teeth, dental restorations, and the masticatory system.

The prevalence of awake bruxism and sleep bruxism in the Dutch adult population

Background

Awake bruxism and sleep bruxism are common conditions amongst adult populations, although prevalence data are scarce.

Objective

This study aimed to assess the prevalence of awake bruxism and sleep bruxism in the Dutch adult population.

Methods

As part of a large epidemiologic survey on oral health of the general Dutch adult population, a total of 1209 subjects were asked about their bruxism behaviour during the day and during their sleep. The collected data were subjected to stratified analysis by five age groups (25‐34, 35‐44, 45‐54, 55‐64 and 65‐74 years), socioeconomic status, and gender.

Results

A prevalence of 5.0% of the total population was found for awake bruxism and of 16.5% for sleep bruxism. Regarding the five age groups, prevalence of 6.5%, 7.8%, 4.0%, 3.2% and 3.0%, respectively, were found for awake bruxism, and of 20.0%, 21.0%, 16.5%, 14.5% and 8.3%, respectively, for sleep bruxism. Women reported both awake bruxism and sleep bruxism more often than men. These differences were statistically significant. Concerning socioeconomic status (SES), both awake bruxism and sleep bruxism were more often found in high SES groups, being statistically significant for awake bruxism only.

Conclusion

Sleep bruxism is a common condition in the Dutch adult population, while awake bruxism is rarer.

Comparison of kinesio taping and occlusal splint in the management of myofascial pain in patients with sleep bruxism

OBJECTIVES

To evaluate the efficacy of Kinesio taping (KT) in patients with sleep bruxism (SB) and to determine whether KT may be an alternative for occlusal splint (OS) for the treatment of SB.

MATERIALS AND METHODS

Sixteen patients with SB were treated with KT (kinesio group) and 18 patients were treated with OS (splint group). Masseter and temporal muscle pressure pain thresholds (MPPT and TPPT), visual analogue scale (VAS) values and mouth opening measurements of patients were compared before treatment, and at the 1st and 5th weeks of treatment.

RESULTS

Both KT and OS treatments significantly reduced muscle pain, decreased VAS values, and increased mouth opening measurements. No statistically significant difference was found between the kinesio and splint groups in terms of MPPT, TPPT, VAS and mouth opening values before treatment and at the 1st and 5th weeks of treatment except for TPPT values at 1st week of treatment where the TPPT values of the kinesio group were significantly higher than the splint group (p< 0.05).

CONCLUSIONS

KT was identified as an easy-to-use treatment method for bruxism and was found to reduce muscle pain and increase mouth opening. KT is at least as effective as OS for the treatment of SB.

Sleep Bruxism and Occurrence of Temporomandibular Disorders-Related Pain: A Polysomnographic Study

Introduction: The diagnosis of sleep bruxism is challenging due to the difficulties involved. Sleep bruxism can lead to clinical consequences, including pain in masticatory muscles, limitation of jaw mobility, headache, and the spectrum of symptoms associated with damage to the teeth and oral mucosa. Currently, only video-polysomnography can definitely diagnose sleep bruxism. Due to the risk of painful temporomandibular disorders (TMD) in sleep bruxers, early diagnosis of pain in the temporomandibular region using questionnaires is recommended. Therefore, this study aimed to assess the relationship between the intensity of sleep bruxism and the occurrence of pain related to TMD. Materials and Methods: This study was conducted on the patients of the Clinic of Prosthetic Dentistry operating at the Department of Prosthetic Dentistry at the Wroclaw Medical University. Based on a positive medical history, a thorough examination for the diagnosis of probable sleep bruxism was carried out in the enrolled patients. Eligible patients were then subjected to a video-polysomnographic study. Each patient was asked to complete the TMD Pain Screener questionnaire to assess the occurrence of pain in jaw and temple area. Results: The results of the study showed that increased bruxism episode index (BEI) was statistically significantly correlated with increase of all types of bruxism episodes-phasic, tonic, and mixed-in all the studied patients; a significant correlation was also found with respect to division of patients into studied and control groups. The study also showed that there was no statistically significant difference between BEI values and scores of TMD Pain Screener. In all the studied patients, a higher BEI was not found to be correlated with the occurrence of TMD-related pain assessed by TMD Pain Screener; similarly, no correlation was found with respect to division of patients into studied and control groups. Conclusions: The occurrence of TMD-related pain is not related to the intensity of sleep bruxism. TMD Pain Screener may be used as an auxiliary tool in the diagnosis or risk of occurrence of TMD-related pain, whereas in the case of sleep bruxism, it has only limited diagnostic value. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03083405.

Association between posterior crossbite and/or deep bite and temporomandibular disorders among Palestinian adolescents: A sex comparison

Objective: To assess the prevalence of temporomandibular disorders (TMDs) and posterior crossbite and/or deep bite and any possible association between them. Methods: One thousand-nineteen adolescents responded to a questionnaire regarding oral habits and TMD symptoms. Afterwards, they were diagnosed according to the Axis I of the DC/TMD and underwent a dental examination. The chi-square test was used for statistical analysis. Results: A significant association  was found between posterior crossbite and some TMD diagnosis, but no association was found between deep bite and TMD, nor between occlusal diagnosis and bruxism. TMDs were more prevalent in girls. There was a significant sex difference (more among females) in the prevalence of painful TMDs. Conclusion: Posterior crossbite in the adolescent population analyzed may be related to TMDs, in contrary to deep-bite. The presence of posterior crossbite may have different impact on TMD findings between the sexes.

The efficacy of low and moderate dosage of diazepam on sleep bruxism in children: A randomized placebo-controlled clinical trial

Background

Sleep bruxism (SB) in children is commonly a self-limited problem; however, therapy of the condition may be needed to improve sleep quality of parents and children. Benzodiazepines have some success in controlling adult bruxism. The objective of this study was to evaluate the effect and the safety of a short course of diazepam on controlling SB in healthy children.

Materials and Methods

In this double-blind, randomized placebo-controlled clinical trial, 109 children with SB were randomly assigned to three groups, receiving low or moderate dose of diazepam or placebo for 2 weeks. For children aged 2-8 years, the dose of 2.5 and 5 mg was considered as low and moderate dose consequently. In children >8 years, the doses were doubled. The severity of SB was evaluated at the beginning and also 2, 8, and 12 weeks thereafter. Data were collected by a questionnaire completed by parents including frequency of SB per week and per night and duration of each SB, as bruxism severity score (BSS). A mixed-model ANOVA was used to assess the differences of mean BSS between different groups and measurement times.

Results

From 109 children recruited, 90 completed the study. After 2 weeks of intervention, the mean BSS decreased significantly in all groups (P = 0.0001), but it was not significantly different between groups in any of follow-ups (P = 0.554). Next-day sleepiness was assessed at week 2 of the study and was significantly higher in the groups using diazepam (P = 0.026).

Conclusion

Short course of diazepam was not more effective than placebo for long-term control of SB in children.

Pre-operative parafunctional or dysfunctional oral habits are associated with the temporomandibular disorders after orthognathic surgery: An observational cohort study

BACKGROUND

Temporomandibular disorders (TMDs) are frequent and disabling, and hence, preventing them is an important health issue. Combining orthodontic and surgical treatments for malocclusions has been shown to affect temporomandibular joint (TMJ) health. However, publications regarding the risk factors that predict negative TMJ outcomes after orthognathic surgery are scarce.

OBJECTIVE

Present prospective cohort study was conducted to identify an association between pre-operative dysfunctional/parafunctional oral habits and the presence of TMD symptoms after orthognathic surgery.

METHOD

We included 237 patients undergoing orthodontics and surgical treatment for malocclusions associated with dentofacial deformities within the Department of Oral and Maxillofacial Surgery of the University of Lille. Their parafunctional and dysfunctional oral habits were recorded through clinical examination along with the presence of TMD symptoms before and after the surgery. According to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) classification, the TMD symptoms studied were myalgia, arthralgia, disc displacement with or without reduction.

RESULTS

Multivariate analysis revealed significant associations among bruxism (odds ratio [OR] 3.17 [1.066; 9.432]), lingual interposition (OR 4.241 [1.351; 13.313]), as well as primary swallowing (OR 3.54 [1.225; 10.234]) and the presence of postoperative symptoms of myalgia. Moreover, a significant association was observed between the presence of any dysfunctional oral habit and postoperative disc displacement with reduction (OR 4.611 [1.249; 17.021]).

CONCLUSION

Bruxism and dysfunctional oral habits were shown to be risk factors for the presence of TMD symptoms also after combined orthodontic and surgical treatment. Treating such habits before orthognathic surgery should help prevent TMD.

International consensus on the assessment of bruxism: Report of a work in progress

In 2013, consensus was obtained on a definition of bruxism as repetitive masticatory muscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible and specified as either sleep bruxism or awake bruxism. In addition, a grading system was proposed to determine the likelihood that a certain assessment of bruxism actually yields a valid outcome. This study discusses the need for an updated consensus and has the following aims: (i) to further clarify the 2013 definition and to develop separate definitions for sleep and awake bruxism; (ii) to determine whether bruxism is a disorder rather than a behaviour that can be a risk factor for certain clinical conditions; (iii) to re-examine the 2013 grading system; and (iv) to develop a research agenda. It was concluded that: (i) sleep and awake bruxism are masticatory muscle activities that occur during sleep (characterised as rhythmic or non-rhythmic) and wakefulness (characterised by repetitive or sustained tooth contact and/or by bracing or thrusting of the mandible), respectively; (ii) in otherwise healthy individuals, bruxism should not be considered as a disorder, but rather as a behaviour that can be a risk (and/or protective) factor for certain clinical consequences; (iii) both non-instrumental approaches (notably self-report) and instrumental approaches (notably electromyography) can be employed to assess bruxism; and (iv) standard cut-off points for establishing the presence or absence of bruxism should not be used in otherwise healthy individuals; rather, bruxism-related masticatory muscle activities should be assessed in the behaviour's continuum.

Dreams of Teeth Falling Out: An Empirical Investigation of Physiological and Psychological Correlates

Teeth dreams (TD), i.e., dreams of teeth falling out or rotting, are one of the most common and universal typical dream themes, yet their source remains unknown and they have rarely been studied empirically. They are especially enigmatic as they do not readily fall under the rubric of the “continuity hypothesis”, i.e., dreams of current and salient waking-life experiences. The aim of the present study was to explore two possible hypotheses for the origin of TD; specifically, TD as incorporation of dental irritation into dreaming, and TD as a symbolic manifestation of psychological distress. Dream themes, dental irritation, psychological distress, and sleep quality were assessed among 210 undergraduates. TD were related to dental irritation (specifically, tension sensations in the teeth, gums, or jaws upon awakening), whereas other dream types were not. Conversely, TD were unrelated to psychological distress, whereas other dream types were (specifically, dreams of being smothered and dreams of falling). This disparity in the correlates of TD existed despite a small but significant relationship between psychological distress and dental irritation. Albeit preliminary, the present findings support the dental irritation hypothesis and do not support the symbolic hypothesis regarding the origins of TD. Research on TD portrays one path through which the mind may distort somatosensory stimuli and incorporate them into dreams as a vivid and emotionally salient image; these preliminary findings highlight the potential of studying TD in order to broaden our understanding of the cognitive mechanisms governing dream production.

Evaluation of Intensity of Sleep Bruxism in Arterial Hypertension

Sleep bruxism (SB) is a masticatory muscle activity during sleep that is characterized as rhythmic (phasic) or non-rhythmic (tonic). The recent hypothesis on the etiology of SB supports the role of the central and autonomic nervous systems. Therefore, in this study, we aimed to assess the intensity of SB in patients with arterial hypertension. A total of 70 adults participated in this study: 35 patients with hypertension (study group) and 35 normotensive subjects (control group). Data were recorded using home portable cardiorespiratory polygraphy. The bruxism episode index (BEI) in the study group was found to be significantly higher compared to the control group (3.4 ± 3.25 vs. 2.35 ± 2.29, p = 0.04). Hypertension, higher body mass index (BMI), lower values of mean oxygen saturation (SpO₂), and a higher percentage of SpO₂ < 90% constituted independent risk factors for increased BEI. These results suggest the need for special oral care in hypertensive patients, patients with higher BMI, lower values of SpO₂ and a higher percentage of SpO₂ < 90%.

The Co-Occurrence of Sexsomnia, Sleep Bruxism and Other Sleep Disorders

Background: Sleep sex also known as sexsomnia or somnambulistic sexual behavior is proposed to be classified as NREM (non-rapid eye movement) parasomnia (as a clinical subtype of disorders of arousal from NREM sleep—primarily confusional arousals or less commonly sleepwalking), but it has also been described in relation to REM (rapid eye movement) parasomnias. Methods: The authors searched the PubMed database to identify relevant publications and present the co-occurrence of sexsomnia and other sleep disorders as a non-systematic review with case series. Results: In the available literature the comorbidity of sexsomnia and other sleep disorders were reported mainly in case reports and less in case series. Sexsomnia was reported both with one and with multiple sleep-related disorders, with NREM parasomnias and obstructive sleep apnea (OSA) being the most commonly reported. Furthermore, the authors enrich the article with new findings concerning two novel cases of sleep bruxism triggering recurrent sexsomnia episodes. Conclusions: Sexsomnia has still not been reported in the literature as often as other parasomnias. The coexistence of sexsomnia and other sleep-related disorders should be more thoroughly examined. This could help both in sexsomnia as well as other sleep-related disorders management.

Masticatory muscle stretching for the management of sleep bruxism: A randomised controlled trial

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.

Association of possible sleep bruxism in children with different chronotype profiles and sleep characteristics

Sleep bruxism (SB) in children has been associated with several sleep characteristics, which may alter their sleep pattern. This change affects the internal biological clock and consequently the chronotype profile. The aim of this study was to evaluate the existence of an association between possible SB in children with specific chronotype profiles and sleep characteristics. The study included 207 parents/guardians of children aged between 3 and 12 years who were waiting for their children's dental treatment at the Pediatric Dentistry Clinic of the Federal University of Rio de Janeiro, Brazil. A questionnaire on the socio-demographic characteristics of parents and children as well as on the features of the children's sleep was applied. In addition, the CIRENS scale (Circadian Energy Scale) was completed by the parents to identify the children's chronotype. A chi-squared test was used to determine the association between possible SB, the chronotype, and sleep characteristics. A multiple logistic regression model was implemented to observe the influence of chronotype, age, and other independent variables on the possible SB. The logistic regression model demonstrated that nocturnal agitation (p = 0.009; OR = 3.42) and nightmares (p = 0.045; OR = 3.24) were associated with possible SB in children. Although no significant association (p = 0 .089) between the chronotype profile and possible SB was observed in the 3 to 5 years age group, a proportional difference was observed between the chronotype categories in this age group-12.5% of children with SB had a morning type, while 26.4% had an intermediate type and 47.8% an evening type compared to those without possible SB. Nocturnal agitation and nightmares were associated with possible SB. In addition, young children with an evening chronotype had a tendency toward possible SB.

Relationship between stress and sleep bruxism in children and their mothers: A case control study

Introduction

Sleep bruxism (SB) is a frequent condition in children. Its pathophysiology involves certain neurotransmitters (serotonin, dopamine, noradrenalin, histamine), but the environment seems to influence its occurrence.

Objective

The objective of this study was to investigate the prevalence of SB in children and their biological mothers, relating it to stress through a case control study.

Methods and Material

The group of cases (SG) was composed of 48 subjects, including 24 children with SB and their mothers, and the control group (CG), formed by 36 children without SB and their mothers. The chi-Square test was used and the probability was computed with 95% confidence intervals (p<0.05). Results: The prevalence of probable awareness of SB in children was 22.6%, while it was 30.8% among caregivers. There were no significant associations between the socio-demographic variables and SB. There was an increase in the occurrence of SB in children (p=0.02) when their caregiver also had this condition.

Conclusions

Psychological stress did not establish a significant relationship with SB in either the child or their mothers.

Decreased γ-aminobutyric acid levels in the brainstem in patients with possible sleep bruxism: A pilot study

BACKGROUND

An increasing number of studies have indicated that the central and autonomic nervous systems play roles in the genesis of sleep bruxism (SB). The role of specific neurochemicals in SB has been a subject of interest.

OBJECTIVE

In this study, we use proton magnetic resonance spectroscopy (¹ H-MRS) to determine whether the levels of γ-aminobutyric acid (GABA) and glutamate (Glu) are different in the brainstem and bilateral cortical masticatory area (CMA) between possible sleep bruxism (SB) patients and controls, and discuss whether the brainstem or cortical networks which may affect the central masticatory pathways are under the genesis of SB.

METHODS

Twelve possible SB patients and twelve age- and gender-matched controls underwent ¹ H-MRS using the "MEGA-Point Resolved Spectroscopy Sequence" (MEGA-PRESS) technique in the brainstem and bilateral CMA. Proton magnetic resonance spectroscopy data were processed using LCModel. Because the signal detected by MEGA-PRESS includes contributions from GABA, macromolecules (primarily proteins) and homocarnosine, the GABA signal is referred to as "GABA+". The glutamate complex (Glx) signal contains both glutamate (Glu) and glutamine (Gln), which mainly reflect glutamatergic metabolism.

RESULTS

Edited spectra were successfully obtained from the bilateral CMA in all subjects. There were no significant differences in neurochemical levels between the left and right CMA in possible SB patients and controls. In the brainstem, significantly lower GABA+ levels were found in possible SB patients than in controls (P = .011), whereas there was no significant difference (P = .307) in Glx levels between the 2 groups.

CONCLUSIONS

SB patients may possess abnormalities in the GABAergic system of brainstem networks.

The effects of stabilization splint treatment on the volume of masseter muscle in sleep bruxism patients

OBJECTIVE

The aim of this study was to evaluate, quantitatively, the volumetric effects of stabilization splint therapy on the masseter muscle of sleep bruxism (SB) patients.

METHODS

The magnetic resonance (MR) images of 16 SB patients diagnosed by polysomnography (PSG) who used stabilization splints for four months were obtained before and after the therapy. The masseter muscle volume was calculated using Cavalieri's principle on the MR images.

RESULTS

After the splint therapy, the mean volume of the masseter muscle did not reduce significantly. The fat and/or water content of the muscles did not change either.

DISCUSSION

The stabilization splint therapy had no effect on the volume, fat and/or water content of the masseter muscle; however the discomfort was reduced in the patients. Although the effect of splint therapy is not fully understood, the non-invasive and reversible stabilization splint can be used in SB patients because of its relaxation effect on muscles.

The potential etiologic factors influencing tinnitus intensity in patients with temporomandibular disorders

OBJECTIVES

To investigate the potential relationships between the intensity of tinnitus associated with temporomandibular disorders (TMD) and potential etiologic factors, including age, gender, freeway space, sleep bruxism (SB), joint clicking, and headache.

METHODS

The sample was comprised of 90 patients without any hearing loss, as confirmed by otorhinolaryngology, who self-reported subjective tinnitus and simultaneous TMD, based on the Research Diagnostic Criteria for TMD (RDC/TMD).

RESULTS

The results showed a positive, weak correlation between the intensity of tinnitus and age (r = 0.225, p = 0.033). The presence of SB and headache were seen in higher proportions in the present sample, at 75.5% (n = 68) and 66.6% (n = 60), respectively.

CONCLUSIONS

In a population of patients with subjective tinnitus and TMD, no significant associations were found between tinnitus intensity and age, freeway space, SB, clicking presence, and headache, though gender did show a weak correlation with tinnitus intensity.

A pilot study of nocturnal temporalis muscle activity in TMD diagnostic groups of women

Temporomandibular disorder (TMD) incidences are believed to be related to parafunctional behaviours like teeth clenching. This pilot study aimed to (i) develop an automated clench-detection algorithm, and (ii) apply the algorithm to test for differences in nocturnal clenching in women with and without TMD. Subjects gave informed consent to participate. Adult women were categorised using Diagnostic Criteria for TMD according to presence/absence (+/-) of both TM joint disc placement (DD) and chronic pain (P) into two groups (+DD+P, -DD-P) with 12 subjects each. Surface temporalis electromyography was recorded during oral tasks performed by subjects at two laboratory sessions. The data were used to characterise muscle activity per N of bite force (μV/N) for each subject, develop the clench-detection algorithm and test its accuracy. Ambulatory surface temporalis electromyography was self-recorded by each subject over three nights and analysed using the algorithm and bite force (N) versus muscle activity μV/N calibrations. Bonferroni-adjusted homoscedastic t-tests assessed for significant between-group differences in clenching (P < 0·05). Sensitivity, specificity and accuracy of algorithm-detected laboratory clenches were all ≥96%. During self-recordings 95% of clenches had durations of <4 s and peak forces of <10 N in both groups. Mean clench durations were significantly longer (P = 0·042) in +DD+P (1·9 ± 0·8 s) than -DD-P subjects (1·4 ± 0·4 s). Mean temporalis duty factors (%clench time/total recording time) were significantly larger (P = 0·041) in +DD+P (0·47 ± 0·34%) than -DD-P (0·26 ±0·22%) subjects. Nocturnal temporalis muscle activities detected by a validated algorithm were longer per clench and recording time in +DD+P compared to -DD-P women.

Sleep and awake bruxism in adults and its relationship with temporomandibular disorders: A systematic review from 2003 to 2014

OBJECTIVE

In order to establish a relationship between bruxism and temporomandibular disorders (TMDs), a systematic review was performed.

MATERIALS AND METHODS

A systematic research was performed based on PubMed, Cochrane Library, Medline, Embase, BIREME, Lilacs and Scielo data bases, between 2003 and 2014 including all languages. Descriptive clinical cases were identified. Two independent authors selected the articles. PICO format was used to analyse the studies and the Newcastle-Ottawa Scale (NOS) was used to verify the quality of the evidence.

RESULTS

Thirty-nine studies (n = 39) were analysed in this review. According to bruxism diagnosis, articles were grouped as follows: polysomnographic diagnosis (PSG) (n = 7), clinical diagnosis (n = 11) and survey/self-report (n = 21). Thirty-three articles (n = 33) established a positive relation between bruxism and TMD and six (n = 6) did not. Quality of evidence was low to moderate. In general, the most part of the studies showed shortcomings on their design with bias risk, and also had a low sensitivity on bruxism diagnosis.

CONCLUSIONS

The evidence based on PSG was not as conclusive as the studies that used surveys and clinical exam to diagnosis bruxism, when bruxism was related to TMD. Sleep bruxism could be associated with myofascial pain, arthralgia and joint pathology as disc displacement and joint noises. Although the evidence at present is inconclusive and does not provide information according to the type of bruxism (bruxism sleep and wakefulness), it is possible to suggest that bruxism would be associated with TMD.

Sleep Bruxism-Tooth Grinding Prevalence, Characteristics and Familial Aggregation: A Large Cross-Sectional Survey and Polysomnographic Validation

STUDY OBJECTIVES

Sleep bruxism (SB) is characterized by tooth grinding and jaw clenching during sleep. Familial factors may contribute to the occurrence of SB. This study aims are: (1) revisit the prevalence and characteristics of SB in a large cross-sectional survey and assess familial aggregation of SB, (2) assess comorbidity such as insomnia and pain, (3) compare survey data in a subset of subjects diagnosed using polysomnography research criteria.

METHODS

A sample of 6,357 individuals from the general population in Quebec, Canada, undertook an online survey to assess the prevalence of SB, comorbidities, and familial aggregation. Data on familial aggregation were compared to 111 SB subjects diagnosed using polysomnography.

RESULTS

Regularly occurring SB was reported by 8.6% of the general population, decreases with age, without any gender difference. SB awareness is concomitant with complaints of difficulties maintaining sleep in 47.6% of the cases. A third of SB positive probands reported pain. A 2.5 risk ratio of having a first-degree family member with SB was found in SB positive probands. The risk of reporting SB in first-degree family ranges from 1.4 to 2.9 with increasing severity of reported SB. Polysomnographic data shows that 37% of SB subjects had at least one first-degree relative with reported SB with a relative risk ratio of 4.625.

CONCLUSIONS

Our results support the heritability of SB-tooth grinding and that sleep quality and pain are concomitant in a significant number of SB subjects.

Sleep bruxism: Current knowledge and contemporary management

Bruxism is defined as the repetitive jaw muscle activity characterized by the clenching or grinding of teeth. It can be categorized into awake and sleep bruxism (SB). Frequent SB occurs in about 13% of adults. The exact etiology of SB is still unknown and probably multifactorial in nature. Current literature suggests that SB is regulated centrally (pathophysiological and psychosocial factors) and not peripherally (morphological factors). Cited consequences of SB include temporomandibular disorders, headaches, tooth wear/fracture, implant, and other restoration failure. Chairside recognition of SB involves the use of subjective reports, clinical examinations, and trial oral splints. Definitive diagnosis of SB can only be achieved using electrophysiological tools. Pharmacological, psychological, and dental strategies had been employed to manage SB. There is at present, no effective treatment that “cures” or “stops” SB permanently. Management is usually directed toward tooth/restoration protection, reduction of bruxism activity, and pain relief.

Is bruxism a disorder or a behaviour? Rethinking the international consensus on defining and grading of bruxism

Inspired by the international consensus on defining and grading of bruxism (Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ et al. J Oral Rehabil. 2013;40:2), this commentary examines its contribution and underlying assumptions for defining sleep bruxism (SB). The consensus' parsimonious redefinition of bruxism as a behaviour is an advance, but we explore an implied question: might SB be more than behaviour? Behaviours do not inherently require clinical treatment, making the consensus-proposed 'diagnostic grading system' inappropriate. However, diagnostic grading might be useful, if SB were considered a disorder. Therefore, to fully appreciate the contribution of the consensus statement, we first consider standards and evidence for determining whether SB is a disorder characterised by harmful dysfunction or a risk factor increasing probability of a disorder. Second, the strengths and weaknesses of the consensus statement's proposed 'diagnostic grading system' are examined. The strongest evidence-to-date does not support SB as disorder as implied by 'diagnosis'. Behaviour alone is not diagnosed; disorders are. Considered even as a grading system of behaviour, the proposed system is weakened by poor sensitivity of self-report for direct polysomnographic (PSG)-classified SB and poor associations between clinical judgments of SB and portable PSG; reliance on dichotomised reports; and failure to consider SB behaviour on a continuum, measurable and definable through valid behavioural observation. To date, evidence for validity of self-report or clinician report in placing SB behaviour on a continuum is lacking, raising concerns about their potential utility in any bruxism behavioural grading system, and handicapping future study of whether SB may be a useful risk factor for, or itself a disorder requiring treatment.