Sleep Bruxism Subjects Research Articles

Effects on general pain perception and dental pulp sensibility in probable sleep bruxism subjects by experimentally induced pain in a pilot study

In this pilot study, the general pain perception and the dental pulp sensibility of probable sleep bruxism (SB) subjects were compared with that of non-SB subjects. The cold pressor test (CPT), electric pulp test (EPT), and thermal pulp test with CO2 snow were executed by one trained dentist (blind to SB diagnosis). A one-factorial multivariate analysis of variance (MANOVA) with SB diagnosis as independent variable and standardized measures regarding pain perception and evaluation was performed. One-hundred-and-five participants (53 SB and 52 non-SB subjects) were included. The one-factorial MANOVA revealed a significant difference between SB and non-SB subjects (p = 0.01) concerning pain perception variables. Post-hoc univariate analyses of variance (ANOVA) showed statistically significant lower general pain tolerance (p = 0.02), higher general subjective sensibility of the teeth (p < 0.01), and a statistical trend for higher subjective dental pain intensity (p = 0.07) in SB subjects. In most of the standardized variables, probable SB subjects seem to react and feel similar to non-SB subjects. However, as probable SB subjects subjectively perceive their teeth to be more sensitive and tend to rate their subjective dental pain intensity more intensely after CO2 testing, data might point to a somatosensory amplification.

Sleep Quality and Comfort Reported by Sleep Bruxism Individuals Wearing the Occlusal Splint and Mandibular Advancement Splint: Revisiting Two Crossover Studies.

To assess (1) whether an occlusal splint (OS) or mandibular advancement splint (MAS) allowed better sleep quality and was more comfortable in individuals with sleep bruxism (SB); and (2) the relationship between sleep quality, comfort, and reduction in RMMA related to SB. Polysomnographic data from 21 SB subjects (mean ± SD age 25.6 ± 4.5 years) collected in two previous studies were compared. Morning self-reports on sleep quality and comfort of the oral device, polysomnographic data, and RMMA index data from no-device nights were compared to nights using an OS or MAS. The reduction ratio of the RMMA index was calculated for both devices. A responder to the oral device was identified when the RMMA index was less than 2 and when it showed a reduction of at least 50% from the no-device control night. Self-reports for sleep quality and comfort of the oral device showed a mild advantage of the OS when compared to the MAS (r2 = 0.47, r2 = 0.32; P ≤ .01). In responders, the MAS induced a greater reduction in the RMMA index (P = .03) than the OS. In the short term, the comfort of the oral device seemed to influence sleep quality in SB individuals. However, despite the slightly higher degree of comfort offered by the OS, the MAS induced a greater effect on the RMMA index. Int J Prosthodont 2022;36:138-147. doi: 10.11607/ijp.7525.

Twelve weeks of occlusal splint treatment reduces blood pressure responses to hypertensive stimuli in those with sleep bruxism

Sleep bruxism (SB) is associated with increased sympathetic tone, a risk for the future development of hypertension. It is unclear whether those with SB would demonstrate exaggerated responses to hypertensive stimuli and whether treatment with an occlusal splint could mitigate these responses. Objectives: This study compared hemodynamic responses to the cold pressor test (CPT) and static handgrip (SHG) to fatigue between controls (CON) and those with SB to determine whether those with SB have exaggerated responses. Methods: Nineteen subjects (9 CON, 10 SB) had heart rate (HR) and blood pressure (BP) responses measured during a CPT and SHG with post-exercise circulatory arrest (PECA). SB subjects underwent a 12-wk occlusal splint intervention followed by a repeat of the experimental protocol. Results: No BP differences existed with pre- (PRE) vs. post-intervention (POST) in the SB subjects. CPT induced larger ΔSBP (10±10 vs. 19±7 mmHg; p &lt; 0.05) and ΔDBP (8±8 vs. 17±9 mmHg; p &lt; 0.05) in SB subjects compared to CON. POST had attenuated ∆SBP (15±9 vs. 8±5 mmHg; p &lt; 0.03) and ∆DBP (18±10 vs. 8±6 mmHg; p &lt; 0.05) during CPT. SB subjects experienced greater ∆DBP (21±11 vs. 31±8; p &lt; 0.05) during SHG which was not different during POST. Conclusions: SB individuals may be at increased risk for the development of hypertension based on exaggerated BP responses to hypertensive stimuli. Twelve weeks of occlusal splint treatment attenuated some of these responses.

Sleep stage-dependent changes in tonic masseter and cortical activities in young subjects with primary sleep bruxism.

The present study investigated the hypothesis that subjects with primary sleep bruxism (SB) exhibit masseter and cortical hyperactivities during quiet sleep periods that are associated with a high frequency of rhythmic masticatory muscle activity (RMMA). Fifteen SB and ten control participants underwent polysomnographic recordings. The frequencies of oromotor events and arousals and the percentage of arousals with oromotor events were assessed. Masseter muscle tone during sleep was quantified using a cluster analysis. Electroencephalography power and heart rate variability were quantified and then compared between the two groups and among sleep stages. The frequency of RMMA and percentage of arousals with RMMA were significantly higher in SB subjects than in controls in all stages, while these variables for nonrhythmic oromotor events did not significantly differ between the groups. In SB subjects, the frequency of RMMA was the highest in stage N1 and the lowest in stages N3 and R, while the percentage of arousals with RMMA was higher in stage N3 than stages N1 and R. The cluster analysis classified masseter activity during sleep into two clusters for masseter tone and contractions. Masseter muscle tone showed typical stage-dependent changes in both groups but did not significantly differ between the groups. Furthermore, no significant differences were observed in electroencephalography power or heart rate variability between the groups. Young SB subjects exhibited sleep stage-dependent increases in the responsiveness of RMMA to transient arousals, but did not show masseter or cortical hyperactivity during sleep.

Botulinum Toxin Therapy for Managing Sleep Bruxism: A Randomized and Placebo-Controlled Trial.

The purpose of this study is to evaluate the effects of botulinum toxin type A (BoNT-A) for managing sleep bruxism (SB) in a randomized, placebo-controlled trial. Thirty SB subjects were randomly assigned into two groups evenly. The placebo group received saline injections into each masseter muscle, and the treatment group received BoNT-A injections into each masseter muscle. Audio–video–polysomnographic recordings in the sleep laboratory were made before, at four weeks after, and at 12 weeks after injection. Sleep and SB parameters were scored according to the diagnostic and coding manual of American Academy of Sleep Medicine. The change of sleep and SB parameters were investigated using repeated measures analysis of variance (RM-ANOVA). Twenty-three subjects completed the study (placebo group 10, treatment group 13). None of the SB episode variables showed a significant time and group interaction (p > 0.05) except for electromyography (EMG) variables. The peak amplitude of EMG bursts during SB showed a significant time and group interaction (p = 0.001). The injection decreased the peak amplitude of EMG bursts during SB only in the treatment group for 12 weeks (p < 0.0001). A single BoNT-A injection cannot reduce the genesis of SB. However, it can be an effective management option for SB by reducing the intensity of the masseter muscle.

Pain perception and functional/occlusal parameters in sleep bruxism subjects following a therapeutic intervention

BackgroundThis study was conducted to assess the individual pain perception in sleep bruxism (SB) subjects. Moreover, the effects of a cognitive behavioural therapy (CBT) compared to an occlusal appliance (OA) on pain perception and a possible continuative impact on several functional parameters were investigated.MethodsA total of 57 SB subjects participated in this investigation. The diagnosis of SB was based on the clinical criteria of the American Academy of Sleep Medicine (AASM). Twenty-eight SB subjects were randomly allocated to the CBT group and 29 to the OA group. The therapeutic intervention took place over a period of 12 weeks, whereby both groups were examined at baseline, immediately after termination of the intervention, and at a 6-month follow-up for pain perception and functional parameters. At each of the three measurement periods, participants completed the pain perception scale and ten functional/occlusal parameters were recorded.ResultsOf the 12 parameters recorded, statistically significant main effects were found for the affective pain perception (p < 0.05) and for the three functional variables. Interestingly, the values obtained for the affective pain perception were considerably below that of a reference group. Apart from the determined statistically significant results, the values recorded for all functional/occlusal variables as well as those obtained for the sensory pain perception were clearly located within normative ranges.ConclusionsWithin the limitations of this study, it might be concluded that the significantly reduced affective pain perception in SB subjects is the expression of an adaptation mechanism.

Does sleep bruxism affect masticatory muscles volume and occlusal force distribution in young subjects? A preliminary study

Objective To compare the differences in masticatory muscle volume and occlusal force distribution between patients with sleep bruxism (SB) and healthy individuals.Methods The study was performed on 14 SB patients and 12 controls aged between 20 and 27 years. Magnetic resonance images from a previous clinical trial were used for volumetric measurements of masticatory muscles. Distribution of bite forces was recorded using T-Scan® II. T-tests were used for data comparison.Results The mean age of the subjects was 23 ± 1.85 years. The mean muscle volumes of patients with SB and healthy subjects were 177.3 and 185.9 cm3, respectively. The mean occlusal force areas were 72.4 pixels and 89.8 pixels for patients with SB and healthy subjects, respectively. There was no significant difference in measurements between groups (p > 0.05).Conclusion There was no significant difference in the distribution of masticatory muscles and occlusal force between young patients with SB and healthy subjects.

The occurrence of respiratory events in young subjects with a frequent rhythmic masticatory muscle activity: a pilot study

PurposeConcomitant occurrence of respiratory events can be often overlooked in the clinical practice of SB. This study assessed physiological characteristics of rhythmic masticatory muscle activity (RMMA) and concomitant respiratory events in young sleep bruxism (SB) subjects asymptomatic to obstructive sleep apnea (OSA). MethodsTwenty-two subjects (age: 24.1±1.9years; F 8: M 14; BMI: 20.2±1.9kg/m2) were polysomnographically diagnosed as moderate-severe SB. Sleep architecture, oromotor (RMMA and non-specific masseter activity [NSMA]) and apnea/hypopnea events were scored. ResultsAll subjects showed normal sleep architecture whereas 6 exhibited respiratory events at a mild level of OSA. In all subjects, RMMA predominantly occurred in Stage N1+N2 while NSMA occurred in Stage N1+N2 (approximately 60 %) and in Stage R (up to 30 %). Up to 50% of respiratory events were scored in Stage R. RMMA occurred more frequently in close association (e.g., within 10s) with respiratory events in 6 subjects with OSA than those without. The percentage of RMMA occurring closely to respiratory events was positively correlated with apnea–hypopnea index (AHI) in Stage N1+N2 only while that of NSMA was positively correlated with AHI in Stage N1+N2 and Stage R. A sub-analysis in 6 subjects with OSA, RMMA after respiratory events was followed to arousals while those before respiratory events were mostly associated with central apnea. ConclusionsA subpopulation of young SB subjects can show concomitant respiratory events. Further large sample studies are needed to demonstrate that the occurrence of subclinical respiratory events represents a clinical subtype of SB.

Neuro-behavioral pattern of sleep bruxism in wakefulness

AbstractIntroduction: Sleep Bruxism (SB) is a non-functional rhythmic movement of the mandible with multifactorial aetiology and complex diagnose. It has been the subject of various studies over the past decades and it is considered a result of actions of the Central Nervous System modulated by Autonomous Nervous System. In this work, we test the hypothesis that SB subjects present a typical and defined neurobehavioral pattern that can be distinct from that of non-bruxers subjects and can be measured during wakefulness. Methods Fifteen sleep bruxers (experimental-group EG) and fifteen non-bruxers (control-group CG) took part in the experiments. To verify the presence and severity of SB, clinical examinations, anamneses and questionnaires, including Visual Analogic Scale - faces (VAS-f) and State-Trait Anxiety Inventory (STAI) were applied. To legitimate the diagnoses of SB, a disposable instrument (Bitestrip®) to assess the masseter activity during sleep was employed. All subjects were submitted to a set of experiments for measuring various visual evoked responses during the presentation of visual stimuli (pleasant, unpleasant and neutral images). Events in Visual Evoked Potential (VEP) were used to compare the neural responses of both CG and EG. Results VAS-f showed EG with higher perception of stress than CG (trait: p=0.05), and lower quality of life for (state: p=0.007). STAI I and II showed significant differences of anxiety between CG and EG (p=0.013 and p=0.004, respectively), being EG the highest. The EG Bitestrip scores confirmed that 100% of subjects were sleep bruxers. Significant differences were found between EG and CG for events associated with emotional (pleasant and unpleasant) images in the first 250 ms after stimulation. In general, EG subjects showed higher amplitude and shorter latency of VEP events. Conclusion It is possible to distinguish between SB and non-bruxers subjects during wakefulness, based on differences in amplitude and latency of cortical event related potentials elicited by visual stimulation. SB subjects show greater amplitudes in specific events in frontal areas when non-pleasant images are shown. Latencies tend to be anticipated in SB compared to CG subjects.

Association between patterns of jaw motor activity during sleep and clinical signs and symptoms of sleep bruxism.

The aim of this study was to investigate the association between patterns of jaw motor activity during sleep and clinical signs and symptoms of sleep bruxism. A total of 35 university students and staff members participated in this study after providing informed consent. All participants were divided into either a sleep bruxism group (n=21) or a control group (n=14), based on the following clinical diagnostic criteria: (1) reports of tooth-grinding sounds for at least two nights a week during the preceding 6months by their sleep partner; (2) presence of tooth attrition with exposed dentin; (3) reports of morning masticatory muscle fatigue or tenderness; and (4) presence of masseter muscle hypertrophy. Video-polysomnography was performed in the sleep laboratory for two nights. Sleep bruxism episodes were measured using masseter electromyography, visually inspected and then categorized into phasic or tonic episodes. Phasic episodes were categorized further into episodes with or without grinding sounds as evaluated by audio signals. Sleep bruxism subjects with reported grinding sounds had a significantly higher total number of phasic episodes with grinding sounds than subjects without reported grinding sounds or controls (Kruskal-Wallis/Steel-Dwass tests; P<0.05). Similarly, sleep bruxism subjects with tooth attrition exhibited significantly longer phasic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P<0.05). Furthermore, sleep bruxism subjects with morning masticatory muscle fatigue or tenderness exhibited significantly longer tonic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P<0.05). These results suggest that each clinical sign and symptom of sleep bruxism represents different aspects of jaw motor activity during sleep.

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

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

Comparative Capabilities of Clinical Assessment, Diagnostic Criteria, and Polysomnography in Detecting Sleep Bruxism.

To evaluate the diagnostic capability of signs and symptoms of sleep bruxism (SB) as per the American Academy of Sleep Medicine (AASM) criteria and a diagnostic grading system proposed by international experts for assessing SB. The study was conducted in three phases (interview, physical examination, and sleep studies). Subjects were asked about self-reported tooth grinding sounds occurring during sleep, muscle fatigue, temporal headaches, jaw muscle pain, and jaw locking. A visual examination was conducted to check for presence of abnormal tooth wear. A full-night polysomnography (PSG) was performed. After three phases, the subjects were divided into two groups matched by age and gender: Case Group, 45 SB subjects, and Control Group, 45 non-SB subjects. Diagnostic accuracy measurements were calculated for each sign or symptom individually and for the two diagnostic criteria analyzed. Muscle fatigue, temporal headaches, and AASM criteria were associated with highest sensitivity (78%, 67%, 58%, respectively) and also with highest diagnostic odds ratio (OR = 9.63, 9.25, 6.33, respectively). Jaw locking, muscle pain, and the criterion of "probable SB" were associated with the worst sensitivity (16%, 18%, 22%, respectively). Presence of muscle fatigue and temporal headaches can be considered good tools to screen SB patients. None of the diagnostic criteria evaluated was able to accurately identify patients with SB. AASM criteria had the strongest diagnostic capabilities and--although they do not attain diagnostic values high enough to replace the current gold standard (PSG)--should be used as a screening tool to identify SB.

Could transient hypoxia be associated with rhythmic masticatory muscle activity in sleep bruxism in the absence of sleep‐disordered breathing? A preliminary report

Sleep bruxism (SB) is a repetitive jaw-muscle activity characterised by clenching or grinding of the teeth during sleep. Sleep bruxism activity is characterised by rhythmic masticatory muscle activity (RMMA). Many but not all RMMA episodes are associated with sleep arousal. The aim of this study was to evaluate whether transient oxygen saturation level change can be temporally associated with genesis of RMMA/SB. Sleep laboratory or home recordings data from 22 SB (tooth grinding history in the absence of reported sleep-disordered breathing) and healthy subjects were analysed. A total of 143 RMMA/SB episodes were classified in four categories: (i) no arousal+no body movement; (ii) arousal+no body movement; (iii) no arousal+body movement; (iv) arousal+body movement. Blood oxygen levels (SaO2 ) were assessed from finger oximetry signal at the baseline (before RMMA), and during RMMA. Significant variation in SaO2 over time (P=0·001) was found after RMMA onset (+7 to +9s). No difference between categories (P=0·91) and no interaction between categories and SaO2 variation over time (P=0·10) were observed. SaO2 of six of 22 subjects (27%) remained equal or slight increase after the RMMA/SB onset (+8s) compared to baseline; 10 subjects (45%) slightly decreased (drop 0·01-1%) and the remaining (27%) decreased between 1% and 2%. These preliminary findings suggest that a subgroup of SB subjects had (i) a minor transient hypoxia potentially associated with the onset of RMMA episodes, and this (ii) independently of concomitant sleep arousal or body movements.

Comparison of platelet serotonin transporter activity in subjects with severe sleep bruxism and control

PurposeThe aim of this study was to evaluate the correlation between sleep bruxism (SB) frequency and serotonin transporter (SERT)-driven serotonin (5-HT)-uptake in platelets. MethodsSubjects were dental trainee residents and faculty members of Okayama University Hospital who were aware of having severe or no SB. SB frequency was assessed for 3-consecutive nights by a self-contained electromyographic detector/analyzer, which indicated individual SB levels as one of four grades (score 0, 1, 2 and 3). Subjects were classified as normal control (NC) when SB scores indicated only 0 or 1 during the 3 nights, or as severe SB for scores 2 or 3. Those subjects whose scores fluctuated from 0 to 3 during the 3 nights were omitted from further analysis. Fasting peripheral venous blood samples were collected in the morning following the final SB assessment. Amounts of SERTs proteins collected from peripheral platelets were quantified using ELISA, and SERTs transport activity was assessed by uptake assay using [3H]-5-HT. ResultsThirteen severe SB subjects and 7 NC subjects were eligible. Gender distribution, mean age, 5-HT concentration and total amounts of SERT protein in platelets showed no significant differences between NC and severe SB (p=0.85: Chi-squared test; p=0.64, 0.26, 0.46: t-test). However, [3H]-5-HT uptake by platelets was significantly greater in NC compared to severe SB subjects (12.79±1.97, 8.27±1.91fmol/105 platelets/min, p<0.001, t-test). ConclusionThe results of this pilot study suggest a possible correlation between peripheral platelet serotonin transporter uptake ability and SB severity.

Analysis of the Effects of a Mandibular Advancement Device on Sleep Bruxism Using Polysomnography, the BiteStrip, the Sleep Assessment Questionnaire, and Occlusal Force

This before and after study evaluated the effects of a mandibular advancement device (MAD) on sleep bruxism (SB) activity and its associated signs and symptoms. Nineteen young adults (39.9 ± 12.9 years, 58% women) with a clinical history of SB without sleep or neurologic disorders and no spontaneous temporomandibular disorder pain were selected. SB activity was assessed after a habituation period of 2 weeks. The results of a 3-month treatment with a thermoplastic monoblock MAD were compared to baseline using electromyogram polysomnography and the BiteStrip, a portable EMG device. Sleep disorders were assessed and validated against the polysomnography sleep assessment questionnaire (SAQ). Additionally, common signs and symptoms of SB were evaluated with the research diagnostic criteria for temporomandibular disorders. Occlusal force was compared to baseline using a cross-arch force transducer. There was a significant improvement in both SB activity and sleep scores (including SB episodes per hour) according to the BiteStrip and the SAQ, respectively. There was also a significant reduction in the signs and symptoms of SB, including grinding and/or clenching, temporomandibular joint (TMJ) sounds, muscle pain, and occlusal force. None of the SB subjects experienced MAD breakage, but in 24% of patients, the MAD treatment had to be interrupted due to TMJ/muscle pain and/or discomfort. The MAD treatment resulted in the reduction of SB activity, SB signs and symptoms, sleep disorders, and occlusal force.

Identification of Sleep Bruxism with an Ambulatory Wireless Recording System

To examine whether an ambulatory bruxism recording system, including a biologic monitor, that measures sleep variables and sympatho-vagal balance can specifically identify sleep bruxism (SB) at home. Twenty-six volunteers, including 16 SB subjects, were recruited. Each participant recorded his or her electromyogram (EMG), sympatho-vagal balance, and sound level for 3 consecutive nights using an audio-video recorder to identify SB. Data of sleep variables were compared among the 3 experimental nights. The episodes were classified into SB episodes with and without grinding and non-SB episodes. EMG patterns, amplitude, sympatho-vagal balance, and sound level of all episodes were analyzed so as to determine the appropriate thresholds to detect SB episodes and grinding sound. Then, all episodes without video-recording data were classified into SB and non-SB episodes by using the appropriate thresholds, and the sensitivity and specificity to detect SB episodes were calculated. With regard to sleep variables, there were no significant differences except for sleep latency between the first and second nights. The appropriate EMG pattern and thresholds of amplitude, sympatho-vagal balance, and sound level were phasic or mixed EMG pattern, 20% of maximum voluntary contraction, mean + 1 SD, and mean + 2 SDs, respectively. The sensitivity and specificity to detect SB episodes were 88.4% and 74.2%, respectively. The results suggest that this system enables the detection of SB episodes at home with considerably high accuracy and little interference with sleep.

Effects of sleep bruxism on functional and occlusal parameters: a prospective controlled investigation

This study was conducted to verify the results of a preceding retrospective pilot study by means of a prospective controlled investigation including a larger sample size. Therefore, the aim of this clinical investigation was to analyze the relationship between sleep bruxism and several functional and occlusal parameters. The null hypothesis of this study was that there would be no differences among sleep bruxism subjects and non-sleep bruxism controls regarding several functional and occlusal parameters. Fifty-eight sleep bruxism subjects and 31 controls participated in this study. The diagnosis sleep bruxism was based on clinical criteria of the American Academy of Sleep Medicine. Sixteen functional and occlusal parameters were recorded clinically or from dental study casts. Similar to the recently published retrospective pilot study, with a mean slide of 0.77 mm (s.d., 0.69 mm) in the sleep bruxism group and a mean slide of 0.4 mm (s.d., 0.57 mm) in the control group, the evaluation of the mean comparison between the two groups demonstrated a larger slide from centric occlusion to maximum intercuspation in sleep bruxism subjects (Mann–Whitney U-test; P=0.008). However, following Bonferroni adjustment, none of the 16 occlusal and functional variables differed significantly between the sleep bruxism subjects and the non-sleep bruxism controls. The present study shows that the occlusal and functional parameters evaluated do not differ between sleep bruxism subjects and non-sleep bruxism subjects. However, as the literature reveals a possible association between bruxism and certain subgroups of temporomandibular disorders, it appears advisable to incorporate the individual adaptive capacity of the stomatognathic system into future investigations.

Sleep bruxism and sleep arousal: an experimental challenge to assess the role of cyclic alternating pattern

Rhythmic masticatory muscle activity (RMMA) is the characteristic electromyographic pattern of sleep bruxism (SB), a sleep-related motor disorder associated with sleep arousal. Sleep arousals are generally organised in a clustered mode known as the cyclic alternating pattern (CAP). CAP is the expression of sleep instability between sleep maintaining processes (phase A1) and stronger arousal processes (phases A2 and A3). This study aimed to investigate the role of sleep instability on RMMA/SB occurrence by analysing CAP and electroencephalographic (EEG) activities. The analysis was performed on the sleep recordings of 8 SB subjects and 8 controls who received sensory stimulations during sleep. Baseline and experimental nights were compared for sleep variables, CAP, and EEG spectral analyses using repeated measure ANOVAs. Overall, no differences in sleep variables and EEG spectra were found between SB subjects and controls. However, SB subjects had higher sleep instability (more phase A3) than controls (P= 0·05). The frequency of phase A3 was higher in the pre-REM sleep periods (P < 0·001), where peaks in RMMA/SB activity were also observed (P = 0·05). When sleep instability was experimentally increased by sensory stimuli, both groups showed an enhancement in EEG theta and alpha power (P = 0·04 and 0·02, respectively) and significant increases in sleep arousal and all CAP variables. No change in RMMA/SB index was found within either groups (RMMA/SB occurred in all SB subjects and only one control during the experimental night). These findings suggest that CAP phase A3 may act as a permissive window rather than a generator of RMMA/SB activity in predisposed individuals.

Clonidine Has a Paradoxical Effect on Cyclic Arousal and Sleep Bruxism during NREM Sleep

Clonidine disrupts the NREM/REM sleep cycle and reduces the incidence of rhythmic masticatory muscle activity (RMMA) characteristic of sleep bruxism (SB). RMMA/SB is associated with brief and transient sleep arousals. This study investigates the effect of clonidine on the cyclic alternating pattern (CAP) in order to explore the role of cyclic arousal fluctuation in RMMA/SB. Polysomnographic recordings from a pharmacological study. University sleep research laboratory. Sixteen SB subjects received a single dose of clonidine or placebo at bedtime in a crossover design. Sleep variables and RMMA/SB index were evaluated. CAP was scored to assess arousal instability between sleep-maintaining processes (phase A1) and stronger arousal processes (phases A2 and A3). Paired t-tests, ANOVAs, and cross-correlations were performed. Under clonidine, CAP time, and particularly the number of A3 phases, increased (P≤0.01). RMMA/SB onset was time correlated with phases A2 and A3 for both placebo and clonidine nights (P≤0.004). However, under clonidine, this positive correlation began up to 40 min before the RMMA/SB episode. CAP phase A3 frequency increased under clonidine, but paradoxically, RMMA/SB decreased. RMMA/SB was associated with and facilitated in CAP phase A2 and A3 rhythms. However, SB generation could be influenced by other factors besides sleep arousal pressure. NREM/REM ultradian cyclic arousal fluctuations may be required for RMMA/SB onset.

Oro‐facial activities in sleep bruxism patients and in normal subjects: a controlled polygraphic and audio–video study

To our knowledge, the large spectrum of sleep motor activities (SMA) present in the head and neck region has not yet been systematically estimated in normal and sleep bruxism (SB) subjects. We hypothesized that in the absence of audio-video signal recordings, normal and SB subjects would present a high level of SMA that might confound the scoring specificity of SB. A retrospective analysis of several SMA, including oro-facial activities (OFA) and rhythmic masticatory muscle activities (RMMA), was made from polygraphic and audio-video recordings of 21 normal subjects and 25 SB patients. Sleep motor activities were scored, blind to subject status, from the second night of sleep recordings. Discrimination of OFA included the following types of activities: lip sucking, head movements, chewing-like movements, swallowing, head rubbing and scratching, eye opening and blinking. These were differentiated from RMMA and tooth grinding. The frequency of SMA per hour of sleep was lower in normal subjects in comparison with SB patients (P < 0.001). Up to 85% of all SMA in normal subjects were related to OFA while 30% of SMA in SB patients were related to OFA scoring (P < 0.001). The frequency of RMMA was seven times higher in SB patients than in normal subjects (P < 0.001). Several SMA can be observed in normal and SB subjects. In the absence of audio-video signal recordings, the discrimination of various types of OFA is difficult to achieve and may lead to erroneous estimation of SB-related activities.