Influence of respiratory allergy and restless sleep on definite sleep bruxism: a cross-sectional clinical study

ObjectiveThis cross-sectional clinical study evaluated the associations between sociodemographic, occupational, clinical conditions, psychological and sleep quality variables on definite sleep bruxism (SB).MethodsAll records obtained from adults (aged 20–60 years) and the elderly (aged >60 years) who had undergone polysomnography (PSG) at a private medical outpatients’ clinic from July 2017 to February 2018 were reviewed. Data from a questionnaire, based on the criteria of the American Academy of Sleep Medicine (AASM), were also gathered. Definite SB data pattern distribution was analyzed, and multivariate Poisson regression with robust variance was used to assess the associations between definite SB diagnosis, determined via PSG recordings, and the independent variables. A significance level of 5% was adopted.ResultsA total of 240 individuals were included in the study and the SB prevalence was 7.08% (n = 17). The adjusted Poisson regression analysis revealed association between definitive SB and individuals with respiratory allergy (PR = 3.63; 95% CI:1.01–13; P = 0.047) and restless sleep (PR = 2.97; 95% CI:1.04–8.50; P = 0.042).ConclusionThis study found associations between definite SB and clinical conditions (respiratory allergy) and sleep behavior (restless sleep). Knowledge regarding factors associated with definite SB can contribute to decision making in the clinical setting and management strategies involving a multidisciplinary approach.     

Treatment of muscle spasticity in patients with cerebral palsy using BTX-A: a pilot study

This study was designed to verify the safety and efficacy of botulinum toxin type A (BTX-A) used as a neuromuscular block on spastic masticatory musculature of children with cerebral palsy. Six patients who had spastic-tetraplegic cerebral-palsy, aged 5 to 20 years were selected. All patients had spasticity of the jaw muscles, bruxism, lower lip trauma, limited mouth opening, and difficulties in cleaning the oral cavity. The patients were sedated under general anesthesia, while the dentist injected the masseter and temporalis muscles bilaterally with 150 and 75 units of BTX-A each. Clinical examinations were conducted at 7, 14, 30, and 90 days after the initial appointment. We found statistically significant decreases in muscle spasticity and bruxism ( p = 0.002), improved inter-incisal opening ( p = 0.002), improved oral hygiene ( p = 0.031), and less lower lip trauma ( p = 0.060) after the neuromuscular blocking.     

Sleep bruxism based on self-report in a nationwide twin cohort

The relative roles of genetic and environmental factors in bruxism are not known. In 1990 a questionnaire sent to the Finnish Twin Cohort yielded responses from 1298 monozygotic and 2419 dizygotic twin pairs aged 33–60 years. We used structural equation modelling to estimate genetic and environmental components of variance in the liability to bruxism. There was a significant gender difference both in childhood (P =0.001) and adult (P =0.007) bruxism. Females compared to males reported childhood bruxism ‘often’ 5.2% vs 4.1% and ‘sometimes’ 17.4% vs 17.3%, and as adults ‘weekly’ 3.7% vs 3.8% and ‘monthly’ 3.9% vs 4.6%, respectively. Bruxism in childhood and adulthood is highly correlated (0.86 in males and 0.87 in females). The proportion of total phenotypic variance in liability to bruxism attributed to genetic influences in childhood bruxism was 49% (95% CI 37–60%) in males and 64% (55–71%) in females, and for adults 39% (27–50%) among males and 53% (44–62%) among females. The correlation between the genetic effects on childhood bruxism and the genetic effects on adult bruxism was estimated in a bivariate model to be 0.95 (95% CI 0.94–0.96) in males and 0.89 (0.88–0.90) in females. Bruxism appears to be quite a persistent trait. There are substantial genetic effects on bruxism both in childhood and as adults, which appear to be highly correlated.     

长沙市3～12岁儿童夜磨牙症流行病学调查

目的了解长沙市3～12岁儿童夜磨牙症的发生情况及相关影响因素。方法2006年6月-2007年4月在长沙市5个行政辖区随机抽取2 706名3～12岁儿童,对受试儿童家长就患儿睡眠状况进行问卷调查。采用Excel表格和SPSS 11.5软件进行数据处理。结果长沙市3～12岁儿童夜磨牙症发病率为9.5%。其中男9.7%,女9.3%,不同性别比较差异无统计学意义(χ2=0.120,P>0.05);3.0～5.9岁组、6.0～8.9岁组和9～12岁组儿童夜磨牙症的发生率分别为11.8%、10.4%和5.5%,不同年龄组间比较差异有统计学意义(χ2=20.588,P<0.01);睡眠姿势仰卧位组、侧卧位组和俯卧位组儿童磨牙症的发生率分别为6.7%、9.7%和11.5%,不同睡眠姿势组间比较差异有统计学意义(χ2=8.924,P<0.05)。打鼾、父亲磨牙、母亲磨牙、夜间睡眠中醒来或哭闹、易冲动好动、父亲狂躁或抑郁、无午睡习惯是儿童夜磨牙症发生的危险因素(P<0.05)。结论长沙市儿童夜磨牙症发病率较高,应引起重视。关注和改善不良影响因素有利于预防和减少夜磨牙症的发生。     

夜磨牙症的临床分析

本文对50名夜磨牙者及50名对照者进行错(牙合)和口颌系统功能检查,结果表明两组间在错(牙合)的发生率无差别,各种错(牙合)类型在两组间的分布也相似,夜磨牙对口领系统的损害常以咀嚼肌症状先表现,而颞下领关节症状出现较晚。     

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.     

Survival rates of anterior composites in managing tooth wear: systematic review

The use of composite restorations for patients with tooth wear is considered as a more conservative treatment option. The aim of this study was to systematically review the literature investigating the survival rates of anterior composite restorations when used in managing tooth wear in patients. PubMed and MEDLINE (Ovid) databases were screened for studies from 1995 to 2015. Cross‐referencing was used to further identify articles. Article selection and data extraction were performed in duplication. Languages were restricted to English. A quality appraisal of included studies was carried out using the Strength of Recommendation Taxonomy system. Six hundred and sixty‐six articles were initially identified from which eight articles were full‐text reviewed. Six articles involving five studies were selected for inclusion. Three studies were prospective and two retrospective. Included studies involved placement of 772 direct and indirect anterior composite restorations in 100 patients with follow‐up periods between 5 months and 10 years. The survival rates of anterior composites were >90% and 50% at 2·5 and 5 years, respectively. Posterior occlusion was re‐established in 91% of patients within 18 months. Meta‐analysis could not be performed due to the heterogeneity of included studies. The systematic review's overall strength of recommendation was graded B. There is evidence to support the use of anterior composite restorations at an increased vertical dimension of occlusion in the short/medium‐term management of tooth wear. Long‐term reporting of outcomes remains limited. Further research is needed with standardised study design, detailed reporting of outcomes and long‐term review.     

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

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