Self‐Reported bruxism and associated factors in Israeli adolescents

Little is known about the epidemiological characteristics of sleep and awake bruxism (SB and AB) in adolescents. The aims of the study were: to assess the prevalence rates of self‐reported SB and AB in Israeli adolescents; to determine the associations between SB/AB and several demographical, exogenous and psychosocial factors in Israeli adolescents; and to investigate the possible concordance between SB and AB. The study made use of a questionnaire. The study population included 1000 students from different high schools in the centre of Israel. Prevalence of self‐reported SB and AB in the Israeli adolescents studied was 9·2% and 19·2%, respectively. No gender difference was found regarding the prevalence of SB and AB. Multiple variable regression analysis revealed that the following predicting variables were related to SB: temporomandibular joint sounds (P = 0·002) and feeling stressed (P = 0·001). The following predicting variables were related to AB: age (P = 0·018), temporomandibular joint sounds (P = 0·002), oro‐facial pain (P = 0·006), and feeling stressed (P = 0·002) or sad (P = 0·006). A significant association was found between SB and AB; that is, an individual reporting SB had a higher probability of reporting AB compared with an individual who did not report SB (odds ratio = 5·099). Chewing gum was the most common parafunction reported by adolescents. The results of this study demonstrate that self‐reports of AB and SB are common in the Israeli adolescents population studied and are not related to gender. The significant correlation found between SB and AB may be a confounding bias that affects proper diagnosis of bruxism through self‐reported questionnaires only.     

Genetic polymorphisms in the serotonergic system are associated with circadian manifestations of bruxism

Bruxism (BRX) is a condition of great interest for researchers and clinicians in dental and medical areas. BRX has two circadian manifestations; it can occur during sleep (sleep bruxism, SB) or during wakefulness (awake bruxism, WB). However, it can be suffered together. Recent investigations suggest that central nervous system neurotransmitters and their genes could be involved in the genesis of BRX. Serotonin is responsible for the circadian rhythm, maintaining arousal, regulating stress response, muscle tone and breathing. Thus, serotonin could be associated with BRX pathogenesis. The aim of this work was to evaluate the frequency of genetic polymorphisms in the genes HTR1A (rs6295), HTR2A (rs1923884, rs4941573, rs6313, rs2770304), HTR2C (rs17260565) and SLC6A4 (rs63749047) in subjects undergoing BRX treatment. Patients included were classified according to their diagnosis in awake bruxism (61 patients), sleep bruxism (26 patients) and both (43 patients). The control group included 59 healthy patients with no signs of BRX. Data showed significant differences in allelic frequencies for the HTR2A rs2770304 polymorphism, where the C allele was associated with increased risk of SB (odds ratio = 2·13, 95% confidence interval: 1·08–4·21, P = 0·03). Our results suggest that polymorphisms in serotonergic pathways are involved in sleep bruxism. Further research is needed to clarify and increase the current understanding of BRX physiopathology.     

Correlation between self‐reported and clinically based diagnoses of bruxism in temporomandibular disorders patients

The present investigation was performed in a population of patients with temporomandibular disorders (TMD), and it was designed to assess the correlation between self‐reported questionnaire‐based bruxism diagnosis and a diagnosis based on history taking plus clinical examination. One‐hundred‐fifty‐nine patients with TMD underwent an assessment including a questionnaire investigating five bruxism‐related items (i.e. sleep grinding, sleep grinding referral by bed partner, sleep clenching, awake clenching, awake grinding) and an interview (i.e. oral history taking with specific focus on bruxism habits) plus a clinical examination to evaluate bruxism signs and symptoms. The correlation between findings of the questionnaire, viz., patients' report, and findings of the interview/oral history taking plus clinical examination, viz., clinicians' diagnosis, was assessed by means of φ coefficient. The highest correlations were achieved for the sleep grinding referral item (φ = 0·932) and for the awake clenching item (φ = 0·811), whilst lower correlation values were found for the other items (φ values ranging from 0·363 to 0·641). The percentage of disagreement between the two diagnostic approaches ranged between 1·8% and 18·2%. Within the limits of the present investigation, it can be suggested that a strong positive correlation between a self‐reported and a clinically based approach to bruxism diagnosis can be achieved as for awake clenching, whilst lower levels of correlation were detected for sleep‐time activities.     

The efficacy of non‐narcotic analgesics on post‐operative endodontic pain: A systematic review and meta‐analysis

The objective of this review was to evaluate the efficacy of non‐narcotic analgesics including non‐steroidal anti‐inflammatory drugs (NSAIDs) and/or paracetamol in the treatment of post‐operative endodontic pain. Additionally, we aimed to examine the possible association of study covariates on the pain scores using meta‐regression analysis. An electronic search was performed in 2016. After data extraction and quality assessment of the included studies (n = 27, representing 2188 patients), meta‐analysis was performed using a random‐effect inverse variance method. Meta‐regression analysis was conducted to examine the associations between effect sizes and study‐level covariates (P < 0·05). The results showed that administration of non‐narcotic analgesic was more effective than placebo in the management of post‐operative pain, resulting in a lower pain scores with a standardised mean difference of ?0·50 (95% CI= ?0·70, ?0·30), ?0·76 (95%CI= ?0·95, ?0·56), ?1·15 (95% CI= ?1·52, ?0·78), ?0·65 (95% CI= ?1·05, ?0·26) for immediately after the procedure, 6?, 12? and 24 h post?operative follow‐ups (test for statistical heterogeneity: P = 0·000, P = 0·000, P = 0·000 and P = 0·001), respectively. Our meta‐regression analysis provided the evidence for association between some study covariates with treatment effect, each at different follow‐ups. We concluded that the clinicians can manage post‐operative endodontic pain by administration of NSAIDs and/or paracetamol. However, analgesic regimens should be considered as important determinants when prescribing a pharmacological adjuvant.     

Risk factors for bruxism among Croatian navy employees

The aim of the study was to evaluate the relationship between bruxism, and sociodemographic parameters, symptoms of temporomandibular disorders (TMD), personality and war experience among Croatian navy employees. The sample included 1092 subjects, aged 20-60 years (mean age 37·06 ± 7·85). An individual's bruxism status was based on clinical oral examination and participants' report of bruxism. Subjects with bruxism index values ≥ 90th percentile were included in severe bruxism group (n = 111), and those with scores below 90th percentile were labelled as negligible bruxism group (n = 981). No differences were found in gender distribution between the two groups. The proportion of military personnel presenting with bruxism is double the proportion of administrative employees with bruxism. A total of 23·34% subjects in negligible bruxism group and 48·65% in severe bruxism group participated in the war. Subjects in severe bruxism group presented more TMD-related signs and symptoms than those in negligible bruxism group. Higher prevalence of neuroticism and psychoticism was found in severe bruxism group. According to logistic regression, the probability of severe bruxism was significantly associated with marital status [Odds ratio (OR) 6·859, 95% confidence interval (CI) 3·869-12·158 P < 0·001], neuroticism (OR 2·842, 95% CI 1·434-5·632 P = 0·003), psychoticism (OR 2·618, 95% CI 1·193-5·746 P = 0·016), military duty (OR 1·828, 95% CI 1·013-3·298 P = 0·045) and masticatory muscles tenderness (OR 9·372, 95% CI 4·923-17·841 P < 0·001). Smokers had a 2·72-fold (95% CI 1·706-4·335 P < 0·001) higher risk of bruxism than non-smokers. Subjects who participated in war were more represented in severe bruxism group. Further studies, including other potential risk factors, are required to clarify these relationships.     

Self‐reported gagging in dentistry: prevalence,psycho‐social correlates and oral health

Although gagging has a profound effect on the delivery of dental care, it is a relatively under‐investigated phenomenon. This study aimed to derive a prevalence estimate of gagging during dental treatment based on patient‐reported information, to determine some socio‐demographic and psychological correlates and to assess the relationship of gagging with self‐reported oral health and avoidance of dental care. Data were collected with a survey among Dutch twin families (n = 11 771). Estimated overall prevalence of gagging during dental treatment was 8·2% (95% CI 7·7–8·7). Patients' self‐report of gagging was found to be significantly associated with female sex, a lower level of education and higher levels of dental trait anxiety, gagging‐related fears (e.g. fear of objects in the mouth), anxious depression and neuroticism. Gagging also appeared to be significantly associated with untreated cavities, gingival bleeding and wearing full dentures, but not with avoidance of dental care. It can be concluded that individuals who report to gag during dental treatment are moderately dentally anxious, fear‐specific situations that can trigger a gagging response and, albeit visiting the dentist equally frequently, report to have a poorer oral health compared to those who do not gag.     

The effect of intermittent use of occlusal splint devices on sleep bruxism: a 4‐week observation with a portable electromyographic recording device

This randomised controlled study investigated the effect of intermittent use of occlusal splints on sleep bruxism compared with that of continuous use by measuring masseter muscle electromyographic activity using a portable electromyographic recording system. Twenty bruxers were randomly allocated to the continuous group and intermittent group. Subjects in the continuous group wore stabilisation splints during sleep for 29 nights continuously, whereas those in the intermittent group wore splints during sleep every other week, that is they used splints on the 1st–7th, 15th–21st and 29th nights. Electromyographic activity of the masseter muscle during sleep was recorded for the following six time points: before (baseline), immediately after, and 1, 2, 3 and 4 weeks after the insertion of a stabilisation splint. The number of nocturnal masseter electromyographic events, duration and the total activity of sleep bruxism were analysed. In the continuous group, nocturnal masseter electromyographic events were significantly reduced immediately and 1 week after the insertion of the stabilisation splint, and duration was reduced immediately after the insertion (P < 0·05, Dunnett's test), but no reduction was observed at 2, 3 and 4 weeks after insertion. In the intermittent group, nocturnal masseter electromyographic events and duration were significantly reduced immediately after and also 4 weeks after insertion of the stabilisation splint (P < 0·05, Dunnett's test). The obtained results of the present exploratory trial indicate that the intermittent use of stabilisation splints may reduce sleep bruxism activity for a longer period compared with that of continuous use.     

Awareness of tooth grinding and clenching from adolescence to young adulthood: a nine‐year follow‐up

Summary How bruxism develops from adolescence to early adulthood remains unclear. A previous database was revisited to evaluate the natural course of self‐reported tooth grinding and clenching among young Finns aged 14–23 using four assessments. Overall, the self‐reported frequencies of both grinding and clenching increased during the examination period: from 13·7% to 21·7% and from 9·2% to 14·8%, respectively. There were significant increases (without a statistically significant difference between genders) in both grinding (P = 0·002) and clenching (P = 0·015) between 15 and 23 years. A significant rise in grinding between 18 and 23 years was also found (P = 0·011). It is concluded that self‐reported bruxism increases from adolescence to young adulthood. Moreover, there are large differences between individuals, and fluctuations may occur in the natural course of bruxism.     

Associations of pain intensity and pain‐related disability with psychological and socio‐demographic factors in patients with temporomandibular disorders: a cross‐sectional study at a specialised dental clinic

The study assessed whether psychological and socio‐demographic factors, including somatisation, depression, stress, anxiety, daytime sleepiness, optimism, gender and age, are associated with pain intensity and pain‐related disability in patients with temporomandibular disorders (TMDs). In total, 320 TMD patients were involved in the study. The psychological status of each patient was assessed with questionnaires, including the Symptom Checklist‐90 (SCL‐90), Epworth Sleeping Scale (ESS), stress questionnaire and Life Orientation Test‐Revised (LOT‐R). TMD pain, including pain intensity and pain‐related disability, was assessed with characteristic pain intensity (CPI) and disability points scales. The associations of psychological and socio‐demographic factors with pain intensity and pain‐related disability were assessed through logistic regression analyses. Higher pain intensity was significantly associated with more severe anxiety (P = 0·004), more severe somatisation (P < 0·001), more severe depression (P < 0·001), more severe stress (P = 0·001) and lower optimism (P = 0·025) in univariate regression analyses. However, multiple regression analysis showed that only somatisation was significantly associated with pain intensity (P < 0·001). Higher pain‐related disability was significantly associated with more severe anxiety (P < 0·001), more severe somatisation (P < 0·001), more severe depression (P < 0·001), more severe stress (P < 0·001) and lower optimism (P = 0·003) in univariate regression analyses. However, multiple regression analysis showed that only depression was significantly associated with pain‐related disability (P = 0·003). Among the psychological and socio‐demographic factors in this study, somatisation was the best predictor of pain intensity, while depression was the best predictor of pain‐related disability.     

A practice‐based clinical evaluation of the survival and success of metal‐ceramic and zirconia molar crowns: 5‐year results

This practice‐based study evaluates the survival and success of conventionally luted metal‐ceramic and zirconia molar crowns fabricated by using a prolonged cooling period for the veneering porcelain. Fifty‐three patients were treated from 07/2008 to 07/2009 with either metal‐ceramic crowns (MCC) or zirconia crowns (ZC). Forty‐five patients (26 female) with 91 restorations (obser‐vational period: 64·0 ± 4·8 months) participated in a clinical follow‐up examination and were included in the study. Estimated cumulative survival (ECSv), success (ECSc) and veneering ceramic success (ECVCSc) were calculated (Kaplan–Meier) and analysed by the crown fabrication technique and the position of the restoration (Cox regression model) (P < 0·05). Five complete failures (MCC: 2, ZC: 3) were recorded (5‐year ECSv: MCC: 97·6%, (95% confidence interval (95%‐CI): [93%; 100%]/ZC: 94·0%, (95%‐CI): [87%; 100%]). Of the MCCs (n = 41), 85·0%, [95%‐CI: (77%; 96%)] remained event‐free, whereas the ECSc for the ZCs (n = 50) was 74·3% (95%‐CI): [61%; 87%]. No significant differences in ECSv (P = 0·51), ECSc (P = 0·43) and ECVCSc (P = 0·36) were detected between the two fabrication techniques. Restorations placed on terminal abutments (n = 44) demonstrated a significantly lower ECVCSc (P = 0·035), (5‐year VCF‐rate: 14·8%) than crowns placed on tooth‐neighboured abutments (n = 47), (5‐year VCF‐rate: 4·3%). In the present study, zirconia molar crowns demonstrated a 5‐year ECSv, ECSc and ECVCSc comparable to MCCs. Irrespective of the fabrication technique, crowns on terminal abutments bear a significantly increased risk for VCFs. Clinical investigations with an increased number of restorations are needed.     

Prevalence of torus palatinus among a group of Japanese elderly

Summary The purpose of this study was to examine the prevalence of torus palatinus (TP) among Japanese elderly and to identify the factors associated with the formation of TP. The subjects were adults aged over 60, who lived independently in the community and attended lectures once a week at the Senior Citizens’ College in Osaka prefecture during 2007 and 2008. A total of 664 subjects, including 294 men and 370 women, were examined, and the mean age was 66·5 ± 4·2 (s.d.). After informed consent was obtained, participants responded to a questionnaire and underwent clinical examination consisting of dental status, temporomandibular symptoms and occlusal force. There were 113 (17·0%) subjects with TP. The prevalence of TP was more frequent in women than in men (24·6% versus 7·5%, P < 0·01). Moreover, there was a significant relationship between the presence of TP and the presence of Torus mandibularis (13·3% versus 25·9%). There was no significant relationship between the prevalence of TP and other factors; diurnal and nocturnal bruxism, occlusal force, occlusal support and temporomandibular diseases symptom. Logistic regression analysis, in which adjustment was made for age and occlusal force, revealed a significant relationship between the presence of TP and gender and the presence of torus mandibularis (TM) (P < 0·001 OR = 3·43, 95%CI = 2·00–5·86; P < 0·001, OR = 2·63, 95%CI = 1·64–4·24, respectively). This study suggests that genetic factors play a more significant role than factors related oromaxillofacial function in the aetiology of TP.     

Effect of a rapid maxillary expansion on snoring and sleep in children: a pilot study

Aim:

The aim of this study was to assess the efficacy of the McNamara rapid palatal expansion device for the treatment of sleep disorders in children.

Methods:

The sample enrolled 12 children aged 4–11 years. Children with snoring and bruxism whose parents did not agree to tonsil surgery were included in the study. During the initial evaluation, a questionnaire addressing sleep was administered, and plaster models were made for the construction of the McNamara rapid maxillary expansion device. The expansion period was 7–15 days, and the McNamara device was removed after 6–8 months. The same questionnaire was administered again after 30 days of use of the orthopedic appliance. The data were analyzed using the McNemar test, with the level of significance set to 5% (P<0·05).

Results:

Significant improvements were found in tiredness upon waking (P?=?0·002), mood (P?=?0·008), lip seal (P?=?0·031), drooling during sleep (P?=?0·031), snoring (P?=?0·001), and bruxism (P?=?0·0062).

Conclusion:

The use of non-invasive methods, such as rapid maxillary expansion, can be an effective treatment for snoring and other undesirable sleep behaviors in children.     

Detection of sleep bruxism: comparison between an electromyographic and electrocardiographic portable holter and polysomnography

Recent polysomnographic (PSG) studies showed that the sleep bruxism (SB) event is preceded by a sudden shift in autonomic cardiac activity. Therefore, heart rate could be the simplest‐to‐record parameter for use in addition to portable home EMG monitoring to improve the accuracy in automatic detection of SB events. The aim of the study was to compare the detection of SB episodes by combined surface electromyography and heart rate (HR) recorded by a compact portable device (Bruxoff^®), with the scoring of SB episodes by a PSG recording. Twenty‐five subjects (14 ‘probable’ bruxers and 11 non‐bruxers) were selected for the study. Each subject underwent the Bruxoff and the PSG recordings during the same night. Rhythmic masseter muscle activities (RMMAs) were scored according to published criteria. Correlation coefficients and the Bland–Altman plots were calculated to measure the correlation and agreement between the two methods. Results showed a high correlation (Pearson's r = 0·95, P < 0·0001) and a high agreement (bias = 0·05) between Bruxoff and the PSG. Furthermore, the receiver operating characteristic curve analysis showed a high sensitivity and specificity of the portable device (92·3% and 91·6%, respectively) when the cut‐off was set at 4 SB episodes per hour according to published criteria. The Bruxoff device showed a good diagnostic accuracy to differentiate RMMA from other oromotor activities. These findings are important in the light of the need for simple and reliable portable devices for the diagnosis of SB both in the clinical and research settings.     

The effect of oral appliances that advanced the mandible forward and limited mouth opening in patients with obstructive sleep apnea: A systematic review and meta‐analysis of randomised controlled trials

Oral appliances (OAs) have demonstrated efficacy in treating obstructive sleep apnea (OSA), but many different OA devices are available. The Japanese Academy of Dental Sleep Medicine supported the use of OAs that advanced the mandible forward and limited mouth opening and suggested an evaluation of their effects in comparison with untreated or CPAP. A systematic search was undertaken in 16 April 2012. The outcome measures of interest were as follows: Apnea Hypopnea Index (AHI), lowest SpO₂, arousal index, Epworth Sleepiness Scale (ESS), the SF‐36 Health Survey. We performed this meta‐analysis using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. Five studies remained eligible after applying the exclusion criteria. Comparing OA and control appliance, OA significantly reduced the weighted mean difference (WMD) in both AHI and the arousal index (favouring OA, AHI: ?7·05 events h^?1; 95% CI, ?12·07 to ?2·03; P = 0·006, arousal index: ?6·95 events h^?1; 95% CI, ?11·75 to ?2·15; P = 0·005). OAs were significantly less effective at reducing the WMD in AHI and improving lowest SpO₂ and SF‐36 than CPAP, (favouring OA, AHI: 6·11 events h^?1; 95% CI, 3·24 to 8·98; P = 0·0001, lowest SpO₂: ?2·52%; 95% CI, ?4·81 to ?0·23; P = 0·03, SF‐36: ?1·80; 95% CI, ?3·17 to ?042; P = 0·01). Apnea Hypopnea Index and arousal index were significantly improved by OA relative to the untreated disease. Apnea Hypopnea Index, lowest SpO₂ and SF‐36 were significantly better with CPAP than with OA. The results of this study suggested that OAs improve OSA compared with untreated. CPAP appears to be more effective in improving OSA than OAs.     

Childhood bruxism: Related factors and impact on oral health‐related quality of life

This study aimed to assess childhood bruxism relating associated factors and the bruxism's impact on oral health‐related quality of life (OHRQoL). A case‐control study was performed with 3‐ to 6‐year‐old children obtained from public preschools in Brazil. The case and control groups had 21 and 40 children, respectively. Associations between bruxism and respiratory problems (p = 0.04, OR: 0.33, CI: 0.09 to 1.14), dental wear (p < 0.01, OR: 0.01, CI: 0.00 to 0.05), malocclusion (p < 0.01, OR: 0.06, CI: 0.01 to 0.35), and dental caries (p = 0.02, OR: 0.22, CI: 0.04 to 1.04) were observed. The OHRQoL overall mean score and subscales were relatively low independent of the evaluated group (p > 0.05). The association between presence and absence of impact with bruxism or other variables showed no statistical relationship (p > 0.05). It could be concluded that childhood bruxism is related to respiratory problems, dental wear, dental caries, and malocclusion. Despite being a topic that demands special care in dentistry, bruxism does not significantly affect the OHRQoL.     

Masticatory function and oral stereognosis in bruxers

Objective: To compare the mastication and oral sensory function of individuals with and without sleep bruxism.

Methods: The sample comprised 60 volunteers, of which 30 were bruxers (mean age = 30.5 ± 6.0) and 30 non-bruxers (mean age = 28.6 ± 3.3). Sleep bruxism was clinically diagnosed and confirmed using the Bruxoff® device. Mastication was evaluated according to swallowing threshold and masticatory efficiency. Swallowing threshold was determined from the median particle size of Optosil®, obtained after an individualized number of masticatory cycles, which was first determined by chewing peanuts; masticatory efficiency was estimated by the sieving method. Oral stereognosis test was used to determine the oral sensory function. Variables were compared using one-way ANOVA (p < .05).

Results: The median particle size, masticatory efficiency, and oral sensory function did not differ significantly between bruxers and non-bruxers (p > .05).

Conclusion: Dentate adults present similar mastication and oral sensory function, despite the presence of sleep bruxism.     

Long‐term use of occlusal appliance has impact on sleep structure

Acrylic occlusal appliances (OAs) have been used for temporomandibular disorders and sleep bruxism, but the effects of the treatment are still insufficiently evaluated. Two all‐night polysomnographic recordings were made in a sleep laboratory on 14 bruxists (9 females and 5 males with mean age of 27·5 years). The measurement included basic polysomnography with additional masseter muscle electromyogram and movement recording (static charge‐sensitive bed method) using randomisation. The base night recording was followed by the second study night after 8 weeks regular use of OA. The OA was made on the occlusal surface of the teeth of the upper jaw, and it was used at night time during the study period. With the OA, rapid eye movement sleep changed from 23·3% to 19·6% (P = 0·078), and slow wave sleep increased significantly from 10·2% to 14·7% (P = 0·039). Masseter contraction (MC) episodes occurred with similar frequency (9·7 vs. 10·5 episodes per hour, P = 0·272). The intensity of the rhythmic MC bursts within an episode decreased from 5·5 to 4·4 (P = 0·027). The groups were post hoc divided into responders and non‐responders using a 20% change in MC episode per hour as a cut‐off point. The results indicated that 43% of bruxists increased activity (negative responders), while 36% decreased (positive responders), and in 21%, there was no change in the level. It is concluded that OA does not have significant feedback inhibition on masseter muscle motor activity during sleep. However, OA may increase slow wave sleep.     

Prevalence of temporomandibular disorder signs in patients with schizophrenia

Summary The aim of this study was to determine the prevalence of temporomandibular disorder (TMD) signs in a group of institutionalized patients with schizophrenia. Three hundred thirty‐nine patients with schizophrenia were examined and compared with 107 age‐matched and gender‐matched control subjects. TMD signs were evaluated according to the Research Diagnostic Criteria to assess temporomandibular joint pain to palpation, limitation of maximum mouth opening, alteration of mouth opening pathway (deviation/deflection) and temporomandibular joint noises. In addition, tooth wear was recorded for the assessment of bruxism. The prevalence of any TMD signs was observed higher (P = 0·001) in the patients with schizophrenia (284/339, 83·7%) than in the controls (72/107, 67·3%). The prevalence of more than one TMD sign was also significantly higher (P = 0·03) in the patients with schizophrenia (131/339, 38·6%) than in the controls (29/107, 27·1%). Significant differences between the two groups were apparent for joint pain on palpation (P = 0·006), deflection (P = 0·006) and joint sounds (P = 0·002). Severe tooth wear was evident in 39·2% of the patients with schizophrenia compared with 21·2% in the control group (P = 0·001). The finding of the present study showed that, compared to control population, chronically hospitalized patients with schizophrenia seem to be more prone to the development of TMD signs and severe tooth wear and bruxism.     

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 +9 s). 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 (+8 s) 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.