Standardised Tool for the Assessment of Bruxism.

OBJECTIVE: This paper aims to present and describe the Standardised Tool for the Assessment of Bruxism (STAB), an instrument that was developed to provide a multidimensional evaluation of bruxism status, comorbid conditions, aetiology and consequences. METHODS: The rationale for creating the tool and the road map that led to the selection of items included in the STAB has been discussed in previous publications. RESULTS: The tool consists of two axes, specifically dedicated to the evaluation of bruxism status and consequences (Axis A) and of bruxism risk and etiological factors and comorbid conditions (Axis B). The tool includes 14 domains, accounting for a total of 66 items. Axis A includes the self-reported information on bruxism status and possible consequences (subject-based report) together with the clinical (examiner report) and instrumental (technology report) assessment. The Subject-Based Assessment (SBA) includes domains on Sleep Bruxism (A1), Awake Bruxism (A2) and Patient's Complaints (A3), with information based on patients' self-report. The Clinically Based Assessment (CBA) includes domains on Joints and Muscles (A4), Intra- and Extra-Oral Tissues (A5) and Teeth and Restorations (A6), based on information collected by an examiner. The Instrumentally Based Assessment (IBA) includes domains on Sleep Bruxism (A7), Awake Bruxism (A8) and the use of Additional Instruments (A9), based on the information gathered with the use of technological devices. Axis B includes the self-reported information (subject-based report) on factors and conditions that may have an etiological or comorbid association with bruxism. It includes domains on Psychosocial Assessment (B1), Concurrent Sleep-related Conditions Assessment (B2), Concurrent Non-Sleep Conditions Assessment (B3), Prescribed Medications and Use of Substances Assessment (B4) and Additional Factors Assessment (B5). As a rule, whenever possible, existing instruments, either in full or partial form (i.e. specific subscales), are included. A user's guide for scoring the different items is also provided to ease administration. CONCLUSIONS: The instrument is now ready for on-field testing and further refinement. It can be anticipated that it will help in collecting data on bruxism in such a comprehensive way to have an impact on several clinical and research fields.

Assessment of awake bruxism by a novel bruxism screener and ecological momentary assessment among patients with masticatory muscle myalgia and healthy controls.

BACKGROUND: Bruxism is a masticatory muscle activity occurring during sleep or wakefulness, involving grinding and clenching of teeth and/or jaw bracing. As yet, the aetiology, epidemiology and consequences of awake bruxism (AB) are largely unknown. OBJECTIVES: The aims of the study were to AB behaviours using a novel bruxism screener (BruxScreen) questionnaire part and Ecological Momentary Assessment (EMA; BruxApp©) on AB behaviours, and to investigate AB's prevalence among masticatory muscle myalgia patients and non-patients. METHODS: Altogether, 115 participants (masticatory myalgia patients referred to a specialist clinic (n = 67) and non-patients (n = 46)) filled in a bruxism screener questionnaire to report bruxism behaviours and jaw symptoms. A selection of both groups did a week-long EMA (patients n = 12, non-patients n = 11) to report AB behaviours. The chi-squared test was used to determine group differences in categorical variables. A logistic regression model was fitted to study the probability of AB. RESULTS: According to BruxScreen, bruxism behaviours and jaw symptoms were more frequent in patients than in non-patients (p < .001). Based on EMA, 14.6% of the behaviour in patients was tooth clenching; for non-patients, this was 0.5% (p < .000). Relaxed muscles were reported by patients and non-patients at 20.6% and 56.4%, respectively (p < .021). Logistic regression, adjusted by age and sex, revealed that patients reported AB 5 times more often than non-patients (OR 4.8, 95% CI 2.1-11.2). CONCLUSION: Awake bruxism behaviours are significantly more frequent in masticatory muscle myalgia patients than non-patients and associate with frequent bruxism-related symptoms. Self-reported teeth clenching seems to be the most significant sign of AB behaviour.

Bruxism in Acute Neurologic Illness.

PURPOSE OF REVIEW: While traditionally encountered in ambulatory settings, bruxism occurs in patients with a variety of acute neurologic illnesses including encephalitis, intracerebral hemorrhage, traumatic brain injury, hypoxic-ischemic encephalopathy, and acute ischemic stroke. Untreated bruxism in acute neurologic illness can lead to tooth loss, difficulty in mouth care resulting in recurrent aspiration pneumonia, endotracheal tube dislodgement, and even tongue laceration or amputation. Inpatient clinicians should be aware of the etiologies and management strategies for bruxism secondary to acute neurologic illness. RECENT FINDINGS: Management strategies for bruxism are varied and include pharmacologic and non-pharmacologic therapies in addition to onabotulinumtoxinA (BoNT-A). Bruxism impacts patients with a variety of acute neurologic illnesses, and emerging evidence suggests successful and safe treatment strategies.

Oral, dental, and craniofacial features in chronic acid sphingomyelinase deficiency.

The aim of this study was to evaluate the oral, dental, and craniofacial features of individuals affected by the chronic forms of acid sphingomyelinase deficiency (ASMD). This study comprised a sample of adult and pediatric patients (n = 8) with chronic ASMD. The individuals underwent oral examinations to evaluate the occurrence of caries, as well as full-mouth periodontal examinations, to assess the occurrence and severity of periodontal diseases. Panoramic and profile radiographs were obtained to analyze dental conditions and craniofacial parameters. Participants also answered questionnaires to identify systemic impairment, parafunctional habits, and bruxism. Dental anomalies of size, shape, and number were found, with agenesis and microdontia being the predominant findings. The average of caries experience was 11.75 (±8.1). Only one patient had periodontal health and all adult individuals had periodontitis at different stages and degrees. Bruxism was found in 87.5% of the sample. The convex profile and maxillary and mandibular retrusion were the most relevant findings in the cephalometric analysis. It is concluded that individuals with chronic ASMD, in addition to several systemic manifestations, present significant modifications in their oral health, from a greater occurrence of dental anomalies, caries, periodontal disease, in addition to skeletal changes.

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.

Parkinson's disease, temporomandibular disorders and bruxism: A pilot study.

BACKGROUND: Even though bruxism and Parkinson's disease (PD) share common characteristics, their relation is still not clear. Both bruxism and PD are movement disorders in addition, patients with bruxism as well as those with PD complain about musculoskeletal pain, including temporomandibular disorders (TMD) pain. OBJECTIVES: Therefore, the aim of this pilot study was to gain more insight into the possible relation between bruxism and TMD on one hand and PD on the other. METHODS: In total, 801 persons gave their written informed consent and agreed to participate in the study filling in a questionnaire. Complete data were collected from 708 persons (368 with PD or Parkinsonism [PR] and 340 controls) and were included in the analysis. The questionnaire included the graded chronic pain scale, the DC/TMD oral behaviour checklist, the DC/TMD symptom questionnaire and the TMD pain screener. In addition, a question about self-reported tooth wear was included. The chi-square test and independent samples t test were used for the data analysis. RESULTS: Patients with PD/PR reported significantly more often bruxism during sleep and wakefulness than controls. Also, patients with PD/PR had more often possible TMD and reported a significantly higher mean pain intensity in the orofacial region than controls. There was no significant difference in complaints of jaw locking between the patient group and the control group. A tendency towards a significant association was found between PD/PR and tooth wear. CONCLUSION: There is a relation between PD/PR and bruxism. Furthermore, a relation of PD/PR with TMD pain is suggested to be present.

Predictors of long-term outcomes in patients undergoing periodontal maintenance.

AIM: This retrospective study aimed to characterize the baseline status of patients following periodontal maintenance, analysing the association between the long-term outcome of these patients, smoking, bruxism, and the main clinical and radiographic variables. MATERIAL AND METHODS: A sample of 174 patients with moderate to severe periodontitis was refined into homogeneous subsamples according to smoking and bruxism and the rate of tooth loss due to periodontal disease (TLPD): 0, 1-2, and >2 teeth. The association and the distribution (χ² test) of the variables within the subsamples were analysed. RESULTS: Smoking and bruxism were significantly associated with higher TLPD rates. Vertical and circumferential bone defects (p < .0001), and abfractions (p < .0001) were associated with bruxism and particularly with bruxism and TLPD >2. Furcation defects (p = .0002), fewer radio-opaque subgingival calculus (χ² p < .0001), a lower mean Gingival index (χ² p = .027), and increased mean recessions >1.5 mm (χ² p = .0026) were associated with smoking and higher TLPD rates. The mean baseline mobility, abfractions, and recessions characterized two basic types of TLPD. CONCLUSIONS: Smoking, bruxism, and routine clinical and radiological parameters can be used to characterize the baseline status of patients with worse outcomes.

Bruxism in Movement Disorders: A Comprehensive Review.

Bruxism is an abnormal repetitive movement disorder characterized by jaw clenching and tooth gnashing or grinding. It is classified into two overlapping types: awake bruxism (AB) and sleep bruxism (SB). Theories on factors causing bruxism are a matter of controversy, but a line of evidence suggests that it may to some extent be linked to basal ganglia dysfunction although so far, this topic has received little attention. The purpose of this article was to review cases of bruxism reported in various movement disorders. The biomedical literature was searched for publications reporting the association of bruxism with various types of movement disorders. As a whole, very few series were found, and most papers corresponded to clinical reports. In Parkinsonian syndromes, AB was rarely reported, but seems to be exacerbated by medical treatment, whereas SB is mainly observed during non-REM sleep, as in restless leg syndrome. AB is occasionally reported in Huntington's disease, primary dystonia, and secondary dystonia; however, its highest incidence and severity is reported in syndromes combining stereotypies and cognitive impairment, such as Rett's syndrome (97%), Down syndrome (42%), and autistic spectrum disorders (32%). Taken as a whole, AB seems to be more frequent in hyperkinetic movement disorders, notably those with stereotypies, and is influenced by anxiety, suggesting an involvement of the limbic part of the basal ganglia in its pathophysiology.

[Chewing on bruxism. Diagnosis, imaging, epidemiology and aetiology]. / Kauwen op bruxisme. Diagnostiek, beeldvorming, epidemiologie en oorzaken.

Since the publication of a special issue on bruxism of the NTvT in July 2000, consensus has been reached on bruxism's definition as a repetitive masticatory muscle activity that is characterised by clenching and/or grinding while awake (awake bruxism) or during sleep (sleep bruxism). As yet, however, no consensus exists about the diagnosis of bruxism: sufficient evidence to establish the reliability and validity of the commonly used techniques (self-report, clinical examination, imaging, electromyography, polysomnography) has not yet been produced. Morphological factors are no longer considered important aetiological factors, while increasing evidence suggests aetiological roles for psychosocial, physiological, biological, and exogenous factors. This review paper is the first part of a diptych and is concerned with the definition, diagnostics, epidemiology and possible causes of this disorder. In the second part, that will be published in the next issue, associations of bruxism with other conditions will be discussed, along with its (purported) consequences and its management.

Temporomandibular Disorders in Psoriasis Patients with and without Psoriatic Arthritis: An Observational Study.

AIMS: Psoriasis is a chronic, remitting and relapsing inflammatory disorder, involving the skin, nails, scalp and mucous membranes, that impairs patients' quality of life to varying degrees. Psoriatic arthritis is a chronic seronegative, inflammatory arthritis, usually preceded by psoriasis. Temporomandibular disorders is a generic term referred to clinical conditions involving the jaw muscles and temporomandibular joint. The aim of this study was to assess symptoms and signs of temporomandibular disorders in psoriasis patients with and without psoriatic arthritis. METHODS: The study group included 112 patients (56 men, 56 women; median age 49.7±12 years) with psoriasis, 25 of them were affected by psoriatic arthritis. A group of 112 subjects without psoriasis (56 men, 56 women; median age 47.7±17 years) served as controls. Signs and symptoms of temporomandibular disorders were evaluated according to the standardized Research Diagnostic Criteria for Temporomandibular Disorders. Psoriasis patients were subgrouped according to the presence/absence of psoriatic arthritis and by gender, to assess the prevalence of traditional symptoms and signs of temporomandibular disorders. RESULTS: Patients with psoriasis, and to an even greater extent those with psoriatic arthritis, were more frequently affected by symptoms and signs of temporomandibular disorders, including an internal temporomandibular joint opening derangement than healthy subjects. A statistically significant increase in symptoms of temporomandibular disorders, in opening derangement, bruxism and sounds of temporomandibular joint was found in patients with psoriatic arthritis as compared with psoriasis patients without arthritis and controls. CONCLUSIONS: psoriasis seems to play a role in temporomandibular joint disorders, causing an increase in orofacial pain and an altered chewing function.

Bruxism and oral parafunctional hyperactivity in social phobia outpatients.

Anxiety and selective serotonin reuptake inhibitors (SSRIs) are considered aggravating factors for bruxism. We examined the influence of anxiety, depression and SSRI on bruxism in social phobia (SP). Twenty-three drug naïve, 17 SSRI-treated SP patients and 33 healthy controls underwent a psychiatric assessment and completed Leibowitz Social Anxiety Scale and Beck Depression Inventory. Oral parafunctional activity (PF) was evaluated by TM-dental examination and by a questionnaire. Drug- naïve and SSRI-treated SP patients did not differ on demographic and clinical measures. Awake bruxism, 'JAW PLAY' and at least one PF were more prevalent in SP than in controls. Severity of SP predicted the presence of PF. SP, but not depression, was associated with higher risk of oral PF and awake bruxism. Chronic SSRI treatment of SP did not affect sleep and awake bruxism. Dental and anxiety screening may improve the prognosis psychiatric and dental patients. Effective treatment of SP may mitigate bruxism.

Women of valor: post-traumatic stress disorder in the dental practice.

Dental professionals can intervene in head, neck and facial pain found in female patients who suffer from post-traumatic stress disorder (PTSD). There are three theories for why women are predisposed to pain: hormonal differences, nervous system rewiring and sympathetic issues. This article includes case studies of three patients who are representative of these theories. A rapid, nonintrusive intervention will also be described.

Oral health, temporomandibular disorder, and masticatory performance in patients with Charcot-Marie-Tooth type 2.

BACKGROUND: The aim of this study was to evaluate the oral health status of temporomandibular disorders (TMD) and bruxism, as well as to measure masticatory performance of subjects with Charcot-Marie-Tooth type 2 (CMT2). METHODS AND RESULTS: The average number of decayed, missing, and filled teeth (DMFT) for both groups, control (CG) and CMT2, was considered low (CG = 2.46; CMT2 = 1.85, P = 0.227). The OHIP-14 score was considered low (CG = 2.86, CMT2 = 5.83, P = 0.899). The prevalence of self-reported TMD was 33.3% and 38.9% (P = 0.718) in CG and CMT2 respectively and for self-reported bruxism was 4.8% (CG) and 22.2% (CMT2), without significant difference between groups (P = 0.162). The most common clinical sign of TMD was masseter (CG = 38.1%; CMT2 = 66.7%) and temporalis (CG = 19.0%; GCMT2 = 33.3%) muscle pain. The geometric mean diameter (GMD) was not significantly different between groups (CG = 4369; CMT2 = 4627, P = 0.157). CONCLUSION: We conclude that the CMT2 disease did not negatively have influence either on oral health status in the presence and severity of TMD and bruxism or on masticatory performance.

A systematic review of etiological and risk factors associated with bruxism.

OBJECTIVE: The aim of the present work was to systematically review the literature and identify all peer-reviewed papers dealing with etiological and risk factors associated with bruxism. DATA SOURCES: Data extraction was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for randomized clinical trials (RCT), controlled clinical trials (CCT) or cohort studies: Cochrane Library, Medline, and Embase from 1980 to 2011. Unpublished literature was searched electronically using ClinicalTrials.gov. DATA SELECTION: The primary outcome was bruxism etiology. Studies should have a standardized method to assess bruxism. DATA EXTRACTION: Screening of eligible studies, assessment of the methodological quality and data extraction were conducted independently and in duplicate. Two reviewers inspected the references using the same search strategy and then applied the same inclusion criteria to the selected studies. They used criteria for methodological quality that was previously described in the Cochrane Handbook. Among the 1247 related articles that were critically assessed, one randomized clinical trial, one controlled clinical trial and seven longitudinal studies were included in the critical appraisal. Of these studies, five were selected, but reported different outcomes. DATA SYNTHESIS: There is convincing evidence that (sleep-related) bruxism can be induced by esophageal acidification and also that it has an important relationship with smoking in a dose-dependent manner. Disturbances in the central dopaminergic system are also implicated in the etiology of bruxism.

Occlusal factors are not related to self-reported bruxism.

AIMS: To estimate the contribution of various occlusal features of the natural dentition that may identify self-reported bruxers compared to nonbruxers. METHODS: Two age- and sex-matched groups of self-reported bruxers (n = 67) and self-reported nonbruxers (n = 75) took part in the study. For each patient, the following occlusal features were clinically assessed: retruded contact position (RCP) to intercuspal contact position (ICP) slide length (< 2 mm was considered normal), vertical overlap (< 0 mm was considered an anterior open bite; > 4 mm, a deep bite), horizontal overlap (> 4 mm was considered a large horizontal overlap), incisor dental midline discrepancy (< 2 mm was considered normal), and the presence of a unilateral posterior crossbite, mediotrusive interferences, and laterotrusive interferences. A multiple logistic regression model was used to identify the significant associations between the assessed occlusal features (independent variables) and self-reported bruxism (dependent variable). RESULTS: Accuracy values to predict self-reported bruxism were unacceptable for all occlusal variables. The only variable remaining in the final regression model was laterotrusive interferences (P = .030). The percentage of explained variance for bruxism by the final multiple regression model was 4.6%. This model including only one occlusal factor showed low positive (58.1%) and negative predictive values (59.7%), thus showing a poor accuracy to predict the presence of self-reported bruxism (59.2%). CONCLUSION: This investigation suggested that the contribution of occlusion to the differentiation between bruxers and nonbruxers is negligible. This finding supports theories that advocate a much diminished role for peripheral anatomical-structural factors in the pathogenesis of bruxism.

Effects of experimental occlusal interferences in individuals reporting different levels of wake-time parafunctions.

AIMS: To test the hypothesis that the effects of an experimental occlusal interference differ between individuals reporting a high or low frequency of wake-time oral parafunctions. METHODS: Study participants reporting very high (HFP group; n = 10) or very low (LFP group; n = 10) levels of oral parafunctions were selected by means of a questionnaire administered to 200 medical students. The selected participants wore an experimental occlusal interference in a single-blind longitudinal study, which comprised different occlusal conditions: interference free (IFC) and active occlusal interference (AIC). Assessments included clinical examination, measurements of nonfunctional tooth contacts, state and trait anxiety, and visual analog scale scores for occlusal discomfort, masticatory muscle pain, and headache. Data were analyzed by repeated measures twoway analysis of variance on ranked data, followed by calculation of within- and between-group differences using Friedman tests and Mann-Whitney tests, respectively. RESULTS: During AIC, the frequency of nonfunctional tooth contacts significantly decreased in both groups (median [interquartile range, IQR]: in HFP from 55.3% [60.0%] to 31.1% [33.5%], P = .03; in LFP from 31.8% [32.4%] to 14.0% [22.8%], P < .01), the decrease being more pronounced in LFP than in HFP (P < .01). Trait anxiety was significantly higher (P = .01) in the HFP group (median, IQR = 22.5, 9.0) than in the LFP group (median, IQR = 19.0, 3.0). The interference caused more occlusal discomfort in the HFP group than in the LFP group (P = .02) and was associated with a significant increase of masticatory muscle pain (P = .05) and headache (P = .04) only in the HFP group. CONCLUSION: The application of an experimental occlusal interference has a different effect in individuals reporting a high or low frequency of oral parafunctions.

Assessment of orofacial characteristics and oral pathology associated with cri-du-chat syndrome.

OBJECTIVE: To obtain a deeper insight into the difficulties individuals with cri-du-chat syndrome experience by means of the analysis of the most common features and oral pathology observed in the subjects enrolled in the study. SUBJECTS AND METHODS: Intra-oral and extra-oral features of a total of 33 patients with cri-du-chat syndrome (the larger sample so far analyzed) through their clinical and photographic examination. Models, orthopantomographies, and teleradiographies have been collected to establish a pattern as accurate as possible of the oral pathology associated with these patients. RESULTS: The present descriptive study shows that patients with cri-du-chat syndrome present with a series of orofacial features such as mandibular retrognathism, high palate, and variable malocclusion, more commonly anterior open-bite. Most patients also present with perioral muscle relaxation with labial incompetence and short philtrum. As regards oral pathology, these patients suffer dental erosions provoked by gastroesophageal reflux and attritions because of intense day-and-night bruxism. CONCLUSION: The odontologists' familiarity with the orofacial pathology associated with cri-du-chat syndrome and with the specific needs such disorder conveys should improve the quality of the buccodental treatment these professionals may offer to these patients.

The study of role of stress in children with behavior disorders and orofacial lesions.

AIM: (1) To study the behavior disorders in children between 5 to 15 years. (2) To study the role of stress in causing behavior disorders. (3) To interpret the orofacial findings in children with behavior disorders. (4) Correlate the orofacial findings with behavior disorder. MATERIALS AND METHODS: Ninty children with behavior problems between age of 5 to 15 years along with their parents who visited the Department of Child-Guidance Clinic, BYL Nair Charitable Hospital, Mumbai. Intraoral examinations were conducted. Behavioral disorders and factors predisposing to those disorders were recorded. RESULTS: Behavior disorders with orofacial lesions was more common in age group of 8 to 10 years. The children were continuously under stress, which manifested in the form of various orofacial disorders or oral lesions. Most common orofacial condition was bruxism. CONCLUSION: Awareness of behavior disorders in dental treatment should guide the pediatric dentist to seek child psychiatric consultation for behavioral disorders to enable early evaluation of the underlying disorder. CLINICAL SIGNIFICANCE: The present study suggested that orofacial and behavior characteristics can serve as markers to diagnose children with behavioral disorders. It also serves as a guide to dental clinicians to refer such children to psychiatrists or pediatricians for early identification, prevention and treatment.

Prospective association of short sleep duration in newborns with bruxism behavior in children: The Japan Environment and Children's Study (JECS).

BACKGROUND: Bruxism is defined as a repetitive masticatory muscle activity, characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. Although the bruxism etiology can be bidirectionally described with sleep disorders, there are few studies available to understand the association of sleep duration with bruxism behavior in early childhood. METHODS: A dataset of children (n = 90,148) from the Japan Environment and Children's Study (JECS) - an ongoing nationwide, prospective birth cohort study - was used to investigate the prospective association of the infant's sleep duration with bruxism behavior, which were acquired using self-reported questionnaire. After multiple imputation of data, the association between sleep duration and bruxism behavior in early childhood was examined using a binomial logistic regression analysis. It was conducted with adjustments for several maternal (e.g., age at delivery and sleep duration) and child-related (e.g., sex and sleep position) variables. RESULTS: The prevalence of bruxism behavior at the ages of two and four were 16.2% and 22.5%, respectively. Using the shortest sleep duration group's participants (≤13 h) as the reference, the odds ratio (95% confidence interval) for prevalence of bruxism behavior decreased with longer sleep duration at one month of age, but not at 36 months of age, after covariate adjustments. Furthermore, in comparison with the impacts between daytime and nighttime sleep, nighttime sleep with longer duration were dominantly associated with bruxism behavior. CONCLUSION: The sleep duration in infant stage, especially during newborn stage was associated with the prevalence of bruxism behavior in children.