Effects of orthodontic aligners on 24-hour masseter muscle activity: a multiple-day electromyographic study.

OBJECTIVE: This study aimed to assess the effects of aligners on masseter muscle activity by using an electromyographic device in the home environment. METHODS: The study was performed on healthy patients who required orthodontic treatment. Three different 24 h-EMG recording sessions were performed in different conditions: without aligners, with passive aligners, and with active aligners. The non-functional MMA work index (nfMMA-WI) and the non-functional MMA time index (nfMMA-TI) for both awake and sleep hours were assessed. ANOVA test was used to compare the average activity during the three recording conditions. RESULTS: On average, a total recording time of 204.7 ± 7.9 hours were provided for each patient. For most patients, ANOVA test showed an absence of significant differences between the recording sessions. CONCLUSIONS: The impact of our results is not negligible: clinicians can find remarkable support to the hypothesis that the use of aligners affects the MMA only in a minority of subjects.

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.

Evidence-based review on temporomandibular disorders among musicians.

BACKGROUND: Playing a musical instrument that loads the masticatory system has frequently been linked to temporomandibular disorders (TMDs). Previous literature reviews on this topic do not conform to the current standards of evidence-based medicine. AIMS: To investigate the effects of playing a musical instrument (i.e. violin/viola and wind instruments) or singing on the presence of TMDs, based on evidence derived from observational studies. METHODS: Databases of Medline, Web of Science and Google Scholar were searched using MeSH and other relevant terms. For each study, a quality assessment was undertaken using a modified version of the Newcastle-Ottawa Scale (NOS). RESULTS: Fifteen relevant papers were identified for inclusion in this review. Of the seven possible points that could be scored with the NOS, the majority of these studies scored under half. Based on the available evidence, the purported relationship between the playing of specific musical instruments and TMDs was not as evident as reported in previous literature reviews. CONCLUSIONS: There is limited evidence to conclude that playing a wind instrument is a hazard to the temporomandibular system. Furthermore, there is no available evidence to suggest that vocalists experience more TMDs than controls. The studies that investigated the presence of TMDs among violists and violinists yielded ambiguous outcomes; some studies reported no association between the playing of these instruments and the presence of signs and symptoms of TMDs, whereas in studies where a clinical examination was performed (though of lower methodological quality), an association was found.

Oral appliance therapy versus nasal continuous positive airway pressure in obstructive sleep apnoea syndrome: a randomised, placebo-controlled trial on self-reported symptoms of common sleep disorders and sleep-related problems.

Obstructive sleep apnoea syndrome (OSAS) is associated with several sleep disorders and sleep-related problems. Therefore, the aim of this study was to compare the effects of a mandibular advancement device (MAD) with those of nasal continuous positive airway pressure (nCPAP) on self-reported symptoms of common sleep disorders and sleep-related problems in mild and moderate OSAS patients. In this randomised placebo-controlled trial, sixty-four OSAS patients (52·0 ± 9·6 years) were randomly assigned to an MAD, nCPAP or an intra-oral placebo appliance in a parallel design. All participants filled out the validated Dutch Sleep Disorders Questionnaire (SDQ) twice: one before treatment and one after six months of treatment. With 88 questions, thirteen scales were constructed, representing common sleep disorders and sleep-related problems. Linear mixed model analyses were performed to study differences between the groups for the different SDQ scales over time. The MAD group showed significant improvements over time in symptoms corresponding with 'insomnia', 'excessive daytime sleepiness', 'psychiatric sleep disorder', 'periodic limb movements', 'sleep apnoea', 'sleep paralysis', 'daytime dysfunction', 'hypnagogic hallucinations/dreaming', 'restless sleep', 'negative conditioning' and 'automatic behaviour' (range of P values: 0·000-0·014). These improvements in symptoms were, however, not significantly different from the improvements in symptoms observed in the nCPAP and placebo groups (range of P values: 0·090-0·897). It can be concluded that there is no significant difference between MAD and nCPAP in their positive effects on self-reported symptoms of common sleep disorders and sleep-related problems in mild and moderate OSAS patients. These beneficial effects may be a result of placebo effects.

Risk factors for injuries associated with damage claims following groin hernia repair.

PURPOSE: Surgical repair of groin hernia should be carried out with minimal complication rates, and it is important to have regular quality control and accurate means of assessment. The Swedish healthcare system has a mutual insurance company (LÖF) that receives claims from patients who have suffered healthcare-related damage or malpractice. The Swedish Hernia Register (SHR) currently covers around 98% of all Swedish groin hernia operations. The aim of this study was to analyse damage claims following groin hernia repair surgery and link these with entries in the SHR, in order to identify risk factors and causes of injuries and malpractice associated with hernia repair. METHODS: Data on all 48,574 groin hernia operations registered in the SHR between 2008 and 2010 were compared and linked with data on claims made to the Swedish National Patient Injury Insurance (LÖF). RESULTS: Of the 130 damage claims received by LÖF, 26 dealt with bleeding, 20 with testicular injury and 7 with intestinal lesions. Eighty (62%) of the complications were considered malpractice according to the Swedish Patient Injury Act. Acute and recurrent surgery, sutured repair and general anaesthesia were associated with a significantly increased risk for a damage claim independently the patients were compensated or not. Females filed claims in greater proportion than males. There was no significant difference in background factors between claims accepted by LÖF and compensated and those who were rejected compensation. CONCLUSION: Risk factors for filing a damage claim included acute surgery, operation for recurrence, sutured repair and general anaesthesia, whereas local anaesthesia reduced the risk.

Treatment of obstructive sleep apnoea patients in community dental care: knowledge and attitudes among general dental practitioners and specialist dentists.

Obstructive sleep apnoea (OSA) is an increasing problem worldwide. Yet, a large number of patients may remain undiagnosed. Dentists could suspect OSA, but little is known about their knowledge and attitudes towards the topic. An email questionnaire was sent to dentists working in Helsinki Health Centre, Helsinki, Finland (n = 226). It consisted of demographic data, items on dentists' overall knowledge of OSA and factors associated with it, and their possibilities and willingness to take part in the recognition and treatment of OSA patients. Altogether, 70·9% (n = 134) of dentists eligible for the study completed the questionnaire. Of them, 79·1% (n = 106) were general practitioners and 20·9% (n = 28) dentists with specialty training. Continuous positive airway pressure (CPAP) (99·3%) and weight control (99·3%) were both generally acknowledged as effective methods to treat OSA. Regarding the efficacy of other treatment modalities, significant differences were found between general practitioners' and specialists' opinions. For example, mandibular advancement devices (MAD) were less often reported by general practitioners (69·8%) than specialists (89·3%) (P < 0·05). The possible risk factors, signs and symptoms, and consequences of OSA were overall well recognised regardless the years in dental profession, but specialists saw more often that nocturnal sweating (P < 0·01) and snoring (P < 0·05) may signify OSA. Dentists could play an important role in suspecting OSA, but they may need more education to cope with that.

Assessment of the progression of tooth wear on dental casts.

Many methods are available for the grading of tooth wear, but their ability to assess the progression of wear over time has not been studied frequently. The aim was to assess whether the occlusal/incisal grading scale of the Tooth Wear Evaluation System (TWES) was sensitive enough for the detection of tooth wear progression from 14 to 23 years of age. A total of 120 sets of dental casts were gathered from 40 people, of whom impressions were made at 14, 18 and 23 years. The TWES was used to assess loss of clinical crown height throughout the entire dentition. There was a significant difference in the TWES scores between the three age groups on all teeth (Friedman tests; P < 0.005 in all cases). Post hoc Wilcoxon tests revealed that the difference between the scores between 14 and 18 years and between 18 and 23 was significant for most teeth. It was concluded that the TWES is sensitive enough to detect changes in tooth wear over time.

Diagnostic accuracy of portable instrumental devices to measure sleep bruxism: a systematic literature review of polysomnographic studies.

This study systematically reviews the sleep bruxism (SB) literature published in the MEDLINE and Scopus databases to answer the following question: What is the validity of the different portable instrumental devices that have been proposed to measure SB if compared with polysomnographic (PSG) recordings assumed as the gold standard? Four clinical studies on humans, assessing the diagnostic accuracy of portable instrumental approaches (i.e. Bitestrip, electromyography (EMG)-telemetry recordings and Bruxoff) with respect to PSG, were included in the review. Methodological shortcomings were identified by QUADAS-2 quality assessment. Findings showed contrasting results and supported only in part the validity of the described diagnostic devices with respect to PSG. The positive predictive value (PPV) of the Bitestrip device was 59-100%, with a sensitivity of 71-84·2%, whilst EMG-telemetry recordings had an unacceptable rate of false-positive findings (76·9%), counterbalanced by an almost perfect sensitivity (98·8%). The Bruxoff device had the highest accuracy values, showing an excellent agreement with PSG for both manual (area under ROC = 0·98) and automatic scoring (0·96) options as well as for the simultaneous recording of events with respect to PSG (0·89-0·91). It can be concluded that the available information on the validity of portable instrumental diagnostic approaches with respect to PSG recordings is still scarce and not solid enough to support any non-PSG technique's employ as a stand-alone diagnostic method in the research setting, with the possible exception of the Bruxoff device that needs to be further confirmed with future investigations.

Bruxism and genetics: a review of the literature.

People who suffer from bruxism (teeth-grinding) often ask their dentists whether their condition is hereditary. The purpose of this study is to enable dentists to provide an 'evidence-based' answer to this question. The biomedical literature was searched using PubMed, and 32 publications were identified, of which nine proved relevant to the research question. The references cited by the publications identified yielded one further publication, bringing the total number of publications included in the analysis to 10. Four publications related to family studies, five related to twin studies and one related to a DNA analysis. With the exception of one of the twin studies, all the included studies concluded that bruxism appears to be (in part) genetically determined. Dentists whose patients ask them about bruxism can therefore tell them that teeth-grinding does indeed 'run in families'.

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.

Bruxism defined and graded: an international consensus.

To date, there is no consensus about the definition and diagnostic grading of bruxism. A written consensus discussion was held among an international group of bruxism experts as to formulate a definition of bruxism and to suggest a grading system for its operationalisation. The expert group defined bruxism as a repetitive jaw-muscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Bruxism has two distinct circadian manifestations: it can occur during sleep (indicated as sleep bruxism) or during wakefulness (indicated as awake bruxism). For the operationalisation of this definition, the expert group proposes a diagnostic grading system of 'possible', 'probable' and 'definite' sleep or awake bruxism. The proposed definition and grading system are suggested for clinical and research purposes in all relevant dental and medical domains.

Are bruxism and the bite causally related?

In the dental profession, the belief that bruxism and dental (mal-)occlusion ('the bite') are causally related is widespread. The aim of this review was to critically assess the available literature on this topic. A PubMed search of the English-language literature, using the query 'Bruxism [Majr] AND (Dental Occlusion [Majr] OR Malocclusion [Majr])', yielded 93 articles, of which 46 papers were finally included in the present review*. Part of the included publications dealt with the possible associations between bruxism and aspects of occlusion, from which it was concluded that neither for occlusal interferences nor for factors related to the anatomy of the oro-facial skeleton, there is any evidence available that they are involved in the aetiology of bruxism. Instead, there is a growing awareness of other factors (viz. psychosocial and behavioural ones) being important in the aetiology of bruxism. Another part of the included papers assessed the possible mediating role of occlusion between bruxism and its purported consequences (e.g. tooth wear, loss of periodontal tissues, and temporomandibular pain and dysfunction). Even though most dentists agree that bruxism may have several adverse effects on the masticatory system, for none of these purported adverse effects, evidence for a mediating role of occlusion and articulation has been found to date. Hence, based on this review, it should be concluded that to date, there is no evidence whatsoever for a causal relationship between bruxism and the bite.

Insurance claims after vascular surgery in Sweden.

OBJECTIVES: The study aimed to estimate the incidence and causes of insurance claims (IC) after vascular surgery (VS) reported to the Swedish Medical Injury Insurance (SMII); and to validate the registration of complications in the National Vascular Registry (Swedvasc). METHODS: The medical records of all IC in VS in Sweden reported to the SMII 2002-2007 were scrutinised and cross-referenced against Swedvasc. RESULTS: There were 193 claims after VS: varicose-veins (66), lower extremity (45), aortic (31) or carotid artery (21), access (19) or other VS (11). Frequent causes of claims were peripheral nerve injury (76), wound infection (22) and cranial nerve injury (15). More than half of the patients suffered permanent injuries, three died. As many as 55 (28%) received economic compensation (an average of 45% of all ICs in SMII). The highest frequency of compensated claims (1:650 yearly procedures) was for carotid artery surgery. Of the procedures, 187 were elective. Compared with the Swedvasc, claudication was a more common indication (28% vs. 12%). Nearly one-fifth (18%) were incorrectly registered in Swedvasc. CONCLUSIONS: The most common causes of insurance claims were peripheral nerve injuries and infections. Patients raising insurance claims after vascular surgery undergo acute procedures less frequently, and are correctly registered in the Swedvasc in 82% of cases.

Bruxism is associated with nicotine dependence: a nationwide Finnish twin cohort study.

OBJECTIVES: To investigate the association of smoking with bruxism while controlling for genetic and environmental factors using a co-twin-control design. Especially, the role of nicotine dependence was studied in this context. METHODS: The material derives from the Finnish Twin Cohort consisting of 12,502 twin individuals who responded to a questionnaire in 1990 (response rate of 77%). All were born in 1930-1957, the mean age being 44 years. The questionnaire covered 103 multiple choice questions, 7 dealing with tobacco use and 22 with sleep and vigilance matters, including perceived bruxism. In addition, a subsample derived from the Nicotine Addiction Genetics Finland Study containing 445 twin individuals was studied. RESULTS: In age- and gender-controlled multinomial logistic regression, both monthly and rarely reported bruxism associated with both current cigarette smoking (odds ratio [OR] = 1.74 and 1.64) and former cigarette smoking (OR = 1.64 and 1.47). Weekly bruxism associated with current smoking (OR = 2.85). Current smokers smoking 20 or more cigarettes a day reported weekly bruxism more likely (OR = 1.61-1.97) than those smoking less. Among twin pairs (N = 142) in which one twin was a weekly bruxer and the cotwin a never bruxer, there were 13 monozygotic pairs in which one twin was a current smoker and the other twin was not. In all cases, the bruxer was the smoker (p = .0003). Nicotine dependence associated significantly with bruxism. CONCLUSIONS: Our twin study provides novel evidence for a possible causal link between tobacco use and bruxism among middle-aged adults. Nicotine dependence may be a significant predisposing factor for bruxism.

Tobacco use and reported bruxism in young adults: a nationwide Finnish Twin Cohort Study.

INTRODUCTION: Higher levels of smoking, leading to increased levels of nicotine and dopamine release, may be more strongly related to bruxism, although this relationship has remained unclear. Thus, the aim of the present study was to investigate the possible effect of cumulative tobacco use on bruxism in a large sample of young adults. METHODS: The material of the present study derives from the FinnTwin16, which consists of five birth cohorts born in 1975-1979. A total of 3,124 subjects (mean age 24 years, range 23-27 years) provided data in 2000-2002 on frequency of bruxism and tobacco use. Multinomial logistic regression was used to explore the relationships of frequency of bruxism with smoking and smokeless tobacco use while controlling covariates (alcohol intoxication, alcohol problems [Rutgers Alcohol Problem Index, RAPI], illicit drug use, psychological distress [General Health Questionnaire], and coffee use). RESULTS: Based on subjective response and multivariate analyses, weekly bruxers were more than two times more likely to report heavy smoking than never bruxers (odds ratio [OR] 2.5, 95 % CI 1.8-3.4). The significant association between heavy smoking and bruxism held when the effects of other tobacco use and multiple covariates were controlled. In addition, the use of smokeless tobacco emerged as an independent risk factor for bruxism. DISCUSSION: Given the observed associations with both heavy smoking and smokeless tobacco and a dose-response relationship, the present results support our hypothesis of a link between nicotine intake and bruxism.

Bruxism and sleep efficiency measured at home with wireless devices.

The present study comprised 101 (48 men) employees of the Finnish Broadcasting Company with or without irregular shift work, but all with a work week of five shifts in a row followed by 2 days off. The mean age of the subjects was 41.0 years (SD = 9.9). The BiteStrip, a single-use disposable EMG device was used for one night during the work week to detect sleep bruxism. The Actiwatch Plus actigraph was worn on the non-dominant wrist for the entire week to evaluate sleep. Total sleep time and fragmentation index, the latter as a measure of sleep efficiency was calculated for the present study. The BiteStrip scores among the participants were: 0- no bruxism: 52.2% (according to the manufacturer, comparable to a sleep laboratory bruxism count of up to 39 over 5 h), 1- mild: 29.3% (40-74 counts), 2- moderate: 12.0%: (75-124 counts) and 3- severe: 6.5% (>125 counts). Severe bruxers slept less during the work week than non-bruxers (P = 0.009), but severe bruxers slept slightly more than non-bruxers during days off. The group means of the sleep fragmentation index decreased from start towards the middle of the work week and increased during days off (P = 0.016). The levels of the fragmentation indices were consistently higher in accordance with bruxism severity (P = 0.013). It was concluded that bruxism has a coherent relationship with sleep efficiency and it can be detected at home with a low cost device.

Lymphotoxin alpha LTA+496C allele is a risk factor for periodontitis in patients with coronary artery disease.

Periodontitis and coronary artery disease (CAD) are inflammatory diseases and associated with each other. The major histocompatibility complex (MHC) region carries genes involved in immune response and inflammation. We investigated whether the MHC genes correlate with the presence of periodontitis or with the occurrence of periodontal pathogens in patients with CAD. Blood and saliva samples from CAD patients (n = 106) were collected at the time of hospitalization. Nine MHC genetic markers [human leukocyte antigen (HLA)-A, HLA-B, HLA-DRB1, lymphotoxin alpha (LTA) +253(a/g), +496(C/T), +633(c/g), +724(C/A), C4A and C4B)] were typed. Based on panoramic tomography, patients were categorized into nonperiodontitis and periodontitis groups. Two major periodontal pathogens, Aggregatibacter (Actinobacillus) actinomycetemcomitans and Porphyromonas gingivalis, were cultivated and polymerase chain reaction-amplified from salivary samples. Serum immunoglobulin (Ig)A and IgG antibody levels to these pathogens were measured. In the univariate analysis, LTA+496C allele (OR = 5.29; 95% CI = 2.07-13.51, P = 0.00027), and the occurrence of P. gingivalis in saliva (OR = 4.74; 95% CI = 1.64-13.70; P = 0.002) were more frequent in periodontitis when compared with nonperiodontitis. Similarly, serum IgA antibody level against the pathogen was increased in periodontitis (P = 0.048). In the multiple logistic regression analysis, when a wide range of covariates was included, the LTA+496C allele (OR = 10.87; 95% CI = 3.23-36.60; P = 0.00012) and the elevated serum IgA antibody level against P. gingivalis (OR = 1.56; 95% CI = 1.05-2.30; P = 0.026) remained as significant risk factors for periodontitis. In conclusion, the major finding of this study is that the LTA+496C allele is associated with periodontitis in patients with CAD.

Fast and reliable active appearance model search for 3-D face tracking.

This paper addresses the three-dimensional (3-D) tracking of pose and animation of the human face in monocular image sequences using active appearance models. The major problem of the classical appearance-based adaptation is the high computational time resulting from the inclusion of a synthesis step in the iterative optimization. Whenever the dimension of the face space is large, a real-time performance cannot be achieved. In this paper, we aim at designing a fast and stable active appearance model search for 3-D face tracking. The main contribution is a search algorithm whose CPU-time is not dependent on the dimension of the face space. Using this algorithm, we show that both the CPU-time and the likelihood of a nonaccurate tracking are reduced. Experiments evaluating the effectiveness of the proposed algorithm are reported, as well as method comparison and tracking synthetic and real image sequences.

Perceived stress, pain and work performance among non-patient working personnel with clinical signs of temporomandibular or neck pain.

The aim of the present study was to assess the associations between different types of perceived stress, pain and work performance among non-patients with clinical signs of muscle pain in the head/neck region. One-fifth (n = 241) of the 1339 media employees who had participated in a previous survey (Ahlberg J. et al., J Psychosom Res 2002; 53: 1077-1081) were randomly selected for standardized clinical examinations. Altogether 49% (n = 118) of these subjects had clinical signs of temporomandibular and/or neck muscle pain and were enrolled in the present study. The mean age of the study sample was 46.9 years (s.d. 6.6) and the female to male distribution 2:1. Of the 118 employees 46.5% reported that the pain problem interfered with their ability to work. Perceived ability to work was not significantly associated with age, gender or work positions. According to logistic regression, reduced work performance was significantly positively associated with continuous pain [odds ratio (OR) 4.38; 95% CI 1.21-15.7], level of perceived pain severity (OR 1.30; 95% CI 1.04-1.63), and health stress (OR 2.08; 95% CI 1.22-3.54). The results of this study indicated an association between specific self-reported stress regarding health and work issues, pain and work performance. From a preventive perspective this indicates a need for increased awareness about these associations on not only individual level but also at the organizational level and in health care.