Comportamiento Mecánico de un Premolar Humano Sano Sometido a Fuerzas Funcionales y Disfuncionales en un MEF / Mechanical Behavior of a Healthy Human Premolar Subjected to Functional and Dysfunctional Forces in a FEM

El propósito de este estudio fue analizar el comportamiento mecánico de la estructura dental sana de un primer premolar inferior humano sometido a fuerzas funcionales y disfuncionales en diferentes direcciones. Se buscó comprender, bajo las variables contempladas, las zonas de concentración de esfuerzos que conllevan al daño estructural de sus constituyentes y tejidos adyacentes. Se realizó el modelo 3D de la reconstrucción de un archivo TAC de un primer premolar inferior, que incluyó esmalte, dentina, ligamento periodontal y hueso alveolar considerando tres variables: dirección, magnitud y área de la fuerza aplicada. La dirección fue dirigida en tres vectores (vertical, tangencial y horizontal) bajo cuatro magnitudes, una funcional de 35 N y tres disfuncionales de 170, 310 y 445 N, aplicadas sobre un área de la cara oclusal y/o vestibular del premolar que involucró tres contactos estabilizadores (A, B y C) y dos paradores de cierre. Los resultados obtenidos explican el fenómeno de combinar tres vectores, cuatro magnitudes y un área de aplicación de la fuerza, donde los valores de esfuerzo efectivo equivalente Von Mises muestran valores máximos a partir de los 60 MPa. Los valores de tensión máximos se localizan, bajo la carga horizontal a 170 N y en el proceso masticatorio en la zona cervical, cuando la fuerza pasa del 60 %. Sobre la base de los hallazgos de este estudio, se puede concluir que la reacción de los tejidos a fuerzas funcionales y disfuncionales varía de acuerdo con la magnitud, dirección y área de aplicación de la fuerza. Los valores de tensión resultan ser más altos bajo la aplicación de fuerzas disfuncionales tanto en magnitud como en dirección, produciendo esfuerzos tensiles significativos para la estructura dental y periodontal cervical, mientras que, bajo las cargas funcionales aplicadas en cualquier dirección, no se generan esfuerzos lesivos. Esto supone el reconocimiento del poder de detrimento estructural del diente y periodonto frente al bruxismo céntrico y excéntrico.

SUMMARY: The purpose of this study was to analyze the mechanical behavior of the healthy dental structure of a human mandibular first premolar subjected to functional and dysfunctional forces in different directions. It was sought to understand, under the contemplated variables, the areas of stress concentration that lead to structural damage of its constituents and adjacent tissues. The 3D model of the reconstruction of a CT file of a lower first premolar was made, which included enamel, dentin, periodontal ligament and alveolar bone considering three variables: direction, magnitude and area of the applied force. The direction was directed in three vectors (vertical, tangential and horizontal) under four magnitudes, one functional of 35 N and three dysfunctional of 170, 310 and 445 N, applied to an area of the occlusal and/or buccal face of the premolar that involved three stabilizing contacts (A, B and C) and two closing stops. The results obtained explain the phenomenon of combining three vectors, four magnitudes and an area of force application, where the values of effective equivalent Von Mises stress show maximum values from 60 MPa. The maximum tension values are located under the horizontal load at 170 N and in the masticatory process in the cervical area, when the force exceeds 60%. Based on the findings of this study, it can be concluded that the reaction of tissues to functional and dysfunctional forces varies according to the magnitude, direction, and area of application of the force. The stress values turn out to be higher under the application of dysfunctional forces both in magnitude and in direction, producing significant tensile stresses for the dental and cervical periodontal structure, while under functional loads applied in any direction, no damaging stresses are generated. This supposes the recognition of the power of structural detriment of the tooth and periodontium against centric and eccentric bruxism.

Identification of Biomechanical Properties of Temporomandibular Discs.

Material: Experimental and model tests were conducted on ten fresh porcine temporomandibular joint discs. The average thickness of disc tissue was, accordingly, 2.77 mm for the anterior zone, 3.98 mm for the posterior, and 1.54 mm for the intermediate. The selection of research material in the form of porcine discs was due to the similarity to human discs. Methods: Discs were loaded in cycles, a temporary course with the amplitude 3 N and frequency 0.07 Hz, and growth in the load was 1 N/s. The selection of load frequency was due to real conditions of temporomandibular joint functioning during mastication. The necessary experimental research was conducted on a testing machine with a measurement range of 2.5 kN. Results: The obtained numeric calculation results indicate that the number of load cycles has a decisive impact on the limitation of energy dispersion capacity through disc tissue. This phenomenon was observed in all the studies on the disc areas. Along with the growth in load cycles, discs are stiffened, and the most significant stiffness was observed in the intermediate area. Conclusions: Based on the conducted research, it should be concluded that excessive load affecting temporomandibular joints caused by the act of mastication and occlusal forces generated during parafunction and in people with defined long-term bruxism has crucial importance on biomechanical disc properties and hence the course of temporomandibular joint conditions.

Music Modulates Awake Bruxism in Chronic Painful Temporomandibular Disorders.

OBJECTIVE: In this experimental study, we aimed to determine whether guided music listening (GML) - a music intervention based on models of mood mediation and attention modulation - modulates masticatory muscle activity and awake bruxism in subjects with chronic painful muscular temporomandibular disorders (TMD myalgia, mTMD), a condition causing a significant burden to patients, their families, and healthcare systems. BACKGROUND: Awake bruxism - a stress behavior characterized by clenching of the teeth - is a strong contributor to chronic mTMD. GML modulates psychological stress and motor responses and could thus reduce muscle activity in chronic musculoskeletal conditions, including mTMD. METHODS: We recorded the electromyographic (EMG) activity in the right masseter of 14 women with chronic (>6 months) mTMD (median [IQR] = 39.5.3 [24.3] years) and 15 pain-free women (median [IQR] = 30.0 [3.5] years) during a GML session, including 3 music (stressful, relaxing, and participants' favorite music) and a no-music (pink noise) control blocks, each lasting 15 minutes. We measured the motor effort of the right masseter relative to the participants' maximum voluntary contraction (MVC), the muscular effort to maintain mandibular posture (EMGposture ), and to produce spontaneous awake bruxism episodes (EMGbruxism ), and the duration and frequency of spontaneous awake bruxism episodes. We tested between-group and within-group (between blocks) differences, as well as the effect of the interaction group by experimental block on these outcome measures. RESULTS: In both groups, EMGposture was significantly affected by the interaction group by experimental block (P < .001). Compared to pink noise [mean (95% CI); mTMD: 2.2 (1.6-2.8) %MVC; Controls: 1.1 (0.5-1.7) %MVC], EMGposture increased during the stressful music block [contrast estimate (95% CI); mTMD: +0.8 (0.7-0.8) %MVC; Controls: +0.3 (0.3-0.4) %MVC; both P < .001], and decreased during the relaxing [mTMD: -0.4 (-0.5 to -0.4) %MVC; Controls: -0.3 (-0.4 to -0.3) %MVC; both P < .001] and favorite [mTMD: -0.5 (-0.6 to -0.5) %MVC; Controls: -0.5 (-0.5 to -0.4) %MVC; both P < .001] music blocks. EMGposture was greater in mTMD individuals than controls during the favorite music [contrast estimate (95% CI): +1.1 (0.2-1.9) %MVC; P = .019] and the pink noise [+1.1 (0.2-2.0) %MVC; P = .014] blocks. EMGbruxism was significantly affected by the interaction group by experimental block (P < .001). In mTMD participants, compared to the pink noise block [mean (95% CI); 23.8 (16.0-31.6) %MVC], EMGbruxism increased during the stressful music block [contrast estimate (95% CI); +10.2 (8.6-11.8) %MVC], and decreased during the relaxing [-6.2 (-8.1 to -4.3) %MVC; P < .001] and favorite [-10.2 (-12.2 to -9.1) %MVC; P < .001] music blocks. These effects were not observed in the control group [mean (95% CI); pink noise: 19.3 (10.9-27.6); stressful: 21.2 (12.9-29.4) %MVC; relaxing: 21.6 (13.3-29.9) %MVC; favorite: 24.2 (15.8-32.7) %MVC; all P > .05]. EMGbruxism was significantly greater in mTMD participants than controls during the stressful music block [contrast estimate (95% CI): +12.9 (1.6-24.2) %MVC; P = .026). GML did not affect the duration or the frequency of awake bruxism in either group (median [IQR], mTMD: 23.5 [96.7] s, range 1-1300 seconds; Controls: 5.5 [22.5], range 0-246 seconds; P = .108). The frequency of awake bruxism episodes was greater in the mTMD group compared to controls only during the pink noise block (median [IQR], mTMD: 5 [15.3] episodes, range 0-62 episodes; Controls: 1 [3] episode, range 0-27 episodes; P = .046). No significant between-group differences were found in either the overall time spent engaging in awake bruxism (median [IQR], mTMD: 23.5 [96.7] s, range 1-1300 seconds; Controls: 5.5 [22.5], range 0-246 seconds; P = .108), or during each block (all P > .05). CONCLUSIONS: In subjects with chronic mTMD, relaxing music and the individual's favorite music decreased the muscular effort during spontaneous awake bruxism episodes by 26% and 44% (relative changes), respectively. In contrast, stressful music increases it by about 43%. Because of its positive effects on awake bruxism, GML with selected music could be a promising and non-invasive component of a multimodal approach for the management of chronic mTMD.

Prevalence and severity of tooth wear and risk factors among young adults in Southern Brazil / Prevalência e gravidade do desgaste dentário e fatores de risco entre adultos jovens no sul do Brasil

Introduction: In studies on the prevalence of tooth wear, few publications related to young adults are found. Ob-jectives: To explore the associations of behavioral, me-dical, and socio-demographic variables with prevalence and severity of tooth wear of the whole dentition, in a sample of young adults, using a modified version of the Tooth Wear Index (TWI). Methods: Sample consisted of 116 university dental students with an average age of 23 years, who answered a questionnaire related to sociode-mographic variables, self-perception and health behaviors. In addition, individuals underwent a clinical evaluation of tooth wear by one trained examiner using the TWI modified by Smith and Knight. Logistic regression was carried out at individual level. Results: A total of 9,906 dental surfaces in 116 individuals were examined, 72.27 % dental surfaces had no tooth wear (grade 0), but all individuals had at least one worn surface. Among the individuals, 78,4 % had grade 1 (enamel) as the highest level and 21.6% grade 2 (dentin) as the highest level. The presence of grade 2 tooth wear was mainly prevalent in the following individuals: male; smoker; with bruxism, and among those who reported having undergone or-thodontic treatment. Analyzing the relevant factors that affect tooth wear by multiple regression analysis, it was found that smoking (OR 6.67; IC 1.73- 25.76) and bruxism (grinding) (OR 4.05; IC 1.29- 12.7) had the greatest effect on tooth wear. Conclusions: Our results suggest that being male, being a current smoker, having grinding bruxism and having previous orthodontic treatment are associated with tooth wear.

Introdução: Nos estudos de prevalência em desgaste dental encontramos poucos trabalhos relacio-nados com adultos jovens. Objetivos: Explorar a associação de variáveis comportamentais, médicas e sociodemográficas com desgaste dentário em uma amostra de adultos jovens, utilizando uma versão modificada do índice Tooth Wear Index (TWI). Métodos: A amostra foi composta por 116 estudantes universitários de Odontologia, com média de 23.3 anos de idade, que responderam a um questionário relacionado às variáveis sociodemográficas, de autopercepção e comportamentais em saúde. Além disso, esses indivíduos foram submetidos a avaliação clínica do desgaste dental por um examinador treinado usando o TWI modificado por Smith e Knight. Regressão logística foi realizada em nível indivi-dual. Resultados: Um total de 9.906 superfícies dentárias em 116 indivíduos foram examinadas, 72,27% das superfícies não apresentavam desgaste dentário (grau 0), mas todos os indivíduos apresentavam pelo menos uma superfície desgastada. Dentre os indivíduos 78,4% apresentaram grau 1 (esmalte) como o nível mais alto e 21,6% grau 2 (dentina) como o mais alto. A presença de desgaste dentário de grau 2 foi principalmente prevalente nos seguintes indivíduos: sexo masculino; fumante; com bruxismo, e entre aqueles que relataram ter realizado tratamento ortodôntico. Analisando os fatores relevantes que afetam o desgaste dentário por análise de regressão múltipla, se verificou que tabagismo (OR = 6,67; IC 1,73-25,76) e bruxismo (OR = 4,05; IC 1,29-12,7) tiveram o maior efeito associado sobre o des-gaste dentário. Conclusões: Nossos resultados sugerem que ser do sexo masculino, tabagista, relatar bruxismo e ter realizado tratamento ortodôntico prévio está associado ao desgaste dentário.

Surface Electrical Stimulation for Persistent Stuttering and Concomitant Orofacial Disorders: A Multiple Case Study.

This multiple case study analysis describes the immediate effects on speech fluency of transcutaneous electrical nerve stimulation (TENS) applied to participants with persistent stuttering and concomitant orofacial disorders. Study participants were 14 adolescents and adults who stuttered and had jaw clenching bruxism or mouth breathing. Participants experienced low-frequency TENS applied at mild motor level for 20 minutes with electrodes placed at the lower third of the face (Area A), submandibular region (Area B), posterior neck (Area C), or shoulder girdle (Area D), with speech fluency assessed immediately before and after each stimulation.For participants with stuttering and bruxism, AB stimulation reduced the median frequency of syllables stuttered by 27% and reduced the median duration of the three highest stuttering moments by 29%. In addition, for participants with stuttering and mouth breathing, CD stimulation reduced the median duration of the three highest stuttering moments by 28% and increased their median speech rate by 113%. As a single session of TENS may help participants with stuttering and concomitant orofacial disorders better use fluency shaping techniques, the therapeutic potential of TENS for treating stuttering should be further investigated.

The association of self-reported awake bruxism with anxiety, depression, pain threshold at pressure, pain vigilance, and quality of life in patients undergoing orthodontic treatment.

INTRODUCTION: This study aimed to evaluate whether the presence of awake bruxism was associated with temporomandibular dysfunction symptoms, pain threshold at pressure, pain vigilance, oral health-related quality of life (OHRQoL), and anxiety and depression symptoms in patients undergoing orthodontic treatment. METHODOLOGY: This observational study followed patients who had started receiving orthodontic treatment for six months. The following variables were measured three times (at baseline, one month, and six months): pressure pain threshold (PPT) in the right and left masseter, anterior temporalis, and temporomandibular joint (TMJ), and right forearm; pain vigilance and awareness questionnaire; and shortened form of the oral health impact profile (OHIP-14). Anxiety and depression symptoms were measured using the Beck anxiety inventory and the Beck depression inventory, respectively. The patients were divided into two main groups according to the presence (n=56) and absence (n=58) of possible awake bruxism. The multi-way analysis of variance (ANOVA) was applied on the date (p=0.050). RESULTS: TMJ and/or muscle pain were not observed in both groups. Time, sex, age group, and awake bruxism did not affect the PPT in the masticatory muscles and pain vigilance (p>0.050). However, the primary effect of awake bruxism was observed when anxiety (ANOVA: F=8.61, p=0.004) and depression (ANOVA: F=6.48, p=0.012) levels were higher and the OHRQoL was lower (ANOVA: F=8.61, p=0.004). CONCLUSION: The patients with self-reported awake bruxism undergoing an orthodontic treatment did not develop TMJ/masticatory muscle pain. The self-reported awake bruxism is associated with higher anxiety and depression levels and a poorer OHRQoL in patients during the orthodontic treatment.

Temporomandibular Disorders and Oral Features in Systemic Lupus Erythematosus Patients: An Observational Study of Symptoms and Signs.

Aims: Systemic Lupus Erythematosus (SLE) is a connective tissue disease characterized by a wide range of pleomorphic pictures, including mucocutaneous, renal, musculoskeletal and neurological symptoms. It involves oral tissues, with hyposalivation, tooth decay, gingivitis, angular cheilitis, ulcers and glossitis. Temporomandibular disorders represent a heterogeneous group of inflammatory or degenerative diseases of the stomatognatic system, with algic and/or dysfunctional clinical features involving temporomandibular joint (TMJ) and related masticatory muscles. The aim of this study was to investigate the prevalence of oral manifestations and temporomandibular disorders (TMD) in SLE patients (Lp) compared with a control group. Methods: Fifty-five patients (9 men and 46 women) with diagnosed Lupus were recruited in the study group. A randomly selected group of 55 patients, matched by sex and age, served as control group. The examination for TMD symptoms and signs was based on the standardized Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) through a questionnaire and clinical examination. Results: Lupus patients complained more frequently (95.8%) of oral and TMJ symptoms (dysgeusia, stomatodynia, masticatory muscle pain during function, neck and shoulder muscles pain and presence of tinnitus) but only xerostomia (χ2=4,1548 p=0,0415), temple headache (χ2=4,4542 p=0,035) and the sensation of a stuck jaw (Mid-p-test p=0,043) were significant. About signs, cheilitis (p=0,0284) oral ulcers (χ2=4,0104 p=0,045) and fissured tongue are significantly more frequent in study group. The salivary flow was significantly decreased in the study group respect to the control one (p<0.0001). As regard to the oral kinematics, restricted movements (RM) in protrusion and left lateral movement were significantly different between study group and controls. In particular, 85,2% of Lp showed limited protrusion versus 56,4% of controls (χ2= 10,91 p<0,001); 59,3% of Lp had also a limitation during left lateral movement versus 47,3% of controls (T=2,225 p=0,0282). About bruxism, only the indentations on the lateral edges of the tongue were found in Lp group (72,7%), with a significant difference respect to controls (χ2=7,37 p=0,007). Conclusions: While masticatory muscles have an overlapping behavior in both groups, the findings collected show a more severe TMJ kinematic impairment in Lp than in controls, with protrusion and left lateral movements significantly different. In addition, a remarkable reduction of salivary flow has been detected in Lp compared to controls. In conclusion, this autoimmune disease seems to play a role in oral manifestations and TMJ disorders, causing an increase in orofacial pain and an altered chewing function.

Bruxism, temporomandibular dysfunction and cervical impairments in females - Results from an observational study.

PURPOSE: Bruxism is highly prevalent and defined as abnormal habitual mouth activity including clenching of the teeth and increased jaw muscle activity. The association between bruxism and temporomandibular dysfunction (TMD) is debated, in particular the association between cervical spine impairments, bruxism, and TMD. Hence the purpose of this study was to identify the relationship between bruxism, TMD, and cervical spine impairments. METHODS: This observational study categorized 55 female volunteers suitable for evaluation to a bruxism (n = 33) or non-bruxism group (n = 22) based on comprehensive screening using questionnaires and visual observation of the mouth by 2 independent dentists. Following this, both groups were evaluated for TMD, severity and location of head/neck pain, neck disability index (NDI), cervical spine impairments, and tissue mechanosensitivity. Regression analysis was used to evaluate the relationship between bruxism, TMD severity, and cervical impairments. RESULTS: Coefficients of pain and bruxism were significantly associated with NDI scores (0.43, p < 0.001; 3.24, p = 0.01) with large and medium sized effects. As a consequence, both severity of TMD and bruxism status are independently associated with cervical impairments. Having TMD is an independent predictor for head/neck pain and cervical impairments. Pain associated with movement tests and tissue mechanosensitivity was found to be an important factor in bruxism. CONCLUSION: Clinicians need to be aware that signs of cervical movement impairment are not likely to be associated with bruxism, rather they should focus on improving orofacial function and tissue mechanosensitivity.

The association of self-reported awake bruxism with anxiety, depression, pain threshold at pressure, pain vigilance, and quality of life in patients undergoing orthodontic treatment

Abstract This study aimed to evaluate whether the presence of awake bruxism was associated with temporomandibular dysfunction symptoms, pain threshold at pressure, pain vigilance, oral health-related quality of life (OHRQoL), and anxiety and depression symptoms in patients undergoing orthodontic treatment. Methodology This observational study followed patients who had started receiving orthodontic treatment for six months. The following variables were measured three times (at baseline, one month, and six months): pressure pain threshold (PPT) in the right and left masseter, anterior temporalis, and temporomandibular joint (TMJ), and right forearm; pain vigilance and awareness questionnaire; and shortened form of the oral health impact profile (OHIP-14). Anxiety and depression symptoms were measured using the Beck anxiety inventory and the Beck depression inventory, respectively. The patients were divided into two main groups according to the presence (n=56) and absence (n=58) of possible awake bruxism. The multi-way analysis of variance (ANOVA) was applied on the date (p=0.050). Results TMJ and/or muscle pain were not observed in both groups. Time, sex, age group, and awake bruxism did not affect the PPT in the masticatory muscles and pain vigilance (p>0.050). However, the primary effect of awake bruxism was observed when anxiety (ANOVA: F=8.61, p=0.004) and depression (ANOVA: F=6.48, p=0.012) levels were higher and the OHRQoL was lower (ANOVA: F=8.61, p=0.004). Conclusion The patients with self-reported awake bruxism undergoing an orthodontic treatment did not develop TMJ/masticatory muscle pain. The self-reported awake bruxism is associated with higher anxiety and depression levels and a poorer OHRQoL in patients during the orthodontic treatment.

The prevalence of bruxism and related factors in patients with multiple sclerosis: a comparative study.

OBJECTIVE: To determine the prevalence of bruxism and related factors in patients with multiple sclerosis (MS). METHODS: Diagnosed with relapsing-remitting MS under the 2010-revised McDonald diagnostic criteria, 182 patients without MS exacerbations during the previous three months were included in the patient group, and 145 healthy individuals made up the control group in the study. Demographic data of the participants in both groups were determined. In the patient and control groups, the diagnosis of definite bruxism was made using the International Classification of Sleep Disorders (Diagnosis and Coding Manual, Second Edition). RESULTS: Bruxism was found in 29.7% (n = 54) of the patients and in 12.4% (n = 18) of the controls, and the difference was statistically significant (p < 0.001). Of all patients, the onset of bruxism was found in 70.4% (n = 38) after the diagnosis and in 29.6% (n = 169) prior to the diagnosis of MS. Compared with those without bruxism, the mean age (p = 0.031) and the score of the Expanded Disability Status Scale (p = 0.001) were also significantly higher among MS patients with bruxism. Between MS patients with and without bruxism, no significant differences were found in terms of sex, marital status, educational status, employment, cigarette smoking, total number of exacerbations, number of exacerbations within the previous year, and drugs used. CONCLUSIONS: The frequency of bruxism was found to be higher in the patients with MS than in the controls. Bruxism is associated with age and the Expanded Disability Status Scale score in MS patients.

The prevalence of bruxism and related factors in patients with multiple sclerosis: a comparative study / A prevalência do bruxismo e fatores relacionados em pacientes com esclerose múltipla: um estudo comparativo

ABSTRACT Objective: To determine the prevalence of bruxism and related factors in patients with multiple sclerosis (MS). Methods: Diagnosed with relapsing-remitting MS under the 2010-revised McDonald diagnostic criteria, 182 patients without MS exacerbations during the previous three months were included in the patient group, and 145 healthy individuals made up the control group in the study. Demographic data of the participants in both groups were determined. In the patient and control groups, the diagnosis of definite bruxism was made using the International Classification of Sleep Disorders (Diagnosis and Coding Manual, Second Edition). Results: Bruxism was found in 29.7% (n = 54) of the patients and in 12.4% (n = 18) of the controls, and the difference was statistically significant (p < 0.001). Of all patients, the onset of bruxism was found in 70.4% (n = 38) after the diagnosis and in 29.6% (n = 169) prior to the diagnosis of MS. Compared with those without bruxism, the mean age (p = 0.031) and the score of the Expanded Disability Status Scale (p = 0.001) were also significantly higher among MS patients with bruxism. Between MS patients with and without bruxism, no significant differences were found in terms of sex, marital status, educational status, employment, cigarette smoking, total number of exacerbations, number of exacerbations within the previous year, and drugs used. Conclusions: The frequency of bruxism was found to be higher in the patients with MS than in the controls. Bruxism is associated with age and the Expanded Disability Status Scale score in MS patients.

RESUMO Objetivo: Neste estudo, pretendeu-se determinar a prevalência de bruxismo e fatores relacionados em pacientes com esclerose múltipla (EM). Métodos: Diagnosticados com EM remitente recidivante sob os critérios de McDonald Diagnostic revisados em 2010, 182 pacientes sem ataques de EM durante os últimos três meses foram incluídos no grupo de pacientes, e 145 indivíduos saudáveis constituíram o grupo de controle no estudo. Os dados demográficos dos participantes dos dois grupos foram determinados. Nos grupos de pacientes e controle, o diagnóstico de bruxismo definitivo foi feito usando a Classificação Internacional de Distúrbios do Sono (1) (Manual de Diagnóstico e Codificação Segunda Edição). Resultados: O bruxismo foi detectado em 29,7% (n = 54) dos pacientes e observado dentro de 12,4% (n = 18) dos controles, e a diferença foi estatisticamente significante (p <0,001). De todos os pacientes, o tempo inicial de bruxismo foi encontrado em 70,4% (n = 38) após o diagnóstico e em 29,6% (n = 169) antes do diagnóstico. Em comparação com aqueles sem bruxismo, os níveis de idade média (p = 0,031) e o escore da Escala de Status de Incapacidade Expandida (p = 0,001) também foram significativamente maiores entre os pacientes com esclerose múltipla com bruxismo. Entre os pacientes com esclerose múltipla com e sem bruxismo, não foi encontrada diferença significativa em termos de sexo, estado civil, status educacional, emprego, tabagismo, número total de ataques, número de ataques no último ano e medicamentos utilizados. Conclusões: A freqüência de bruxismo foi maior em pacientes com esclerose múltipla do que nos controles. O bruxismo está associado à idade e ao escore da Escala de Status de Incapacidade Expandida (EDSS) em pacientes com EM.

Fulminant thymomatous AMPAR-antibody limbic encephalitis with hypertonic coma, bruxism, an isoelectric electroencephalogram and temporal cortical atrophy, with recovery.

Autoimmune encephalitides are a potentially devastating group of treatable disorders with a wide variety of clinical presentations. The most studied autoimmune encephalitis is caused by antibodies to the N-methyl-D-aspartate glutamate receptor. A rarer cause is due to antibodies against the evolutionarily related α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR). The full assortment of electroencephalogram (EEG) and clinical descriptions of the latter are yet to be fully described. A 44-year-old woman with impaired consciousness and subsequent coma characterised by an isoelectric EEG was diagnosed with AMPAR-antibody limbic encephalitis. MRI revealed temporal T2 hyperintensities that improved with immunosuppression, although leaving marked cortical atrophy. Gradual clinical improvement saw the development of aggressive bruxism requiring botulinum toxin injection with eventual meaningful clinical recovery. This case expands the clinical spectrum of AMPAR limbic encephalitis to include aggressive bruxism, and highlights that despite poor clinical and EEG findings at the outset, recovery is still possible.

Occlusion time analysis in military pilots affected by bruxism.

Military pilots are characterized by peculiar job conditions related to intense accelerative stresses. For this, they frequently report work-related neck and back pain and are affected by bruxism. The aim of this case-control study is to analyze the occlusion time (OT) in a sample of military pilots affected by bruxism, compared with healthy non-pilot subjects. 14 military pilots, all males (mean age 35.14 ± 2.32 y), affected by bruxism, were compared with an age matched control group of 14 male subjects (mean age 32.29 ± 4.84 y). The T-Scan computerized occlusal analysis system (Tek-Scan Inc., Boston, MA, USA) was used to record the subjects' occlusion times during 4 mandibular opening-closing movements. Military pilots affected by bruxism showed a statistically significant lower (reduced of 85%) mean OT, compared with control subjects (p < 0.0001). Military pilots are characterized by a highly reduced occlusion time compared to healthy non-pilot subjects. This feature could not be only related with the presence of bruxism but with their particular clinical job-related condition that causes different dental and stomatognathic system problems. Further studies are encouraged to enhance the scientific knowledge in this field.

Effect of breathing type on electromyographic activity of respiratory muscles during tooth clenching at different decubitus positions.

OBJECTIVE: To compare the effect of breathing type on electromyographic (EMG) activity of respiratory muscles during tooth clenching at different decubitus positions. METHODS: Forty young men participants were included, 11 with upper costal, 9 with mixed, and 20 with costo-diaphragmatic breathing type. EMG recordings of diaphragm (DIA), external intercostal (EIC), sternocleidomastoid (SCM), and latissimus dorsi (LAT) muscles during tooth clenching in the intercuspal position were performed in dorsal, left lateral, and ventral decubitus positions. RESULTS: DIA EMG activity was higher in subjects with upper costal or mixed than with costodiaphragmatic breathing type (p = 0.006; 0.021, respectively), whereas it was similar between upper costal and mixed breathing types. EIC, SCM, and LAT activity was similar among breathing types. CONCLUSION: Higher DIA activity would be a risk factor to exceed the adaptive capability of healthy subjects with upper costal or mixed breathing type.

Pre-operative parafunctional or dysfunctional oral habits are associated with the temporomandibular disorders after orthognathic surgery: An observational cohort study.

BACKGROUND: Temporomandibular disorders (TMDs) are frequent and disabling, and hence, preventing them is an important health issue. Combining orthodontic and surgical treatments for malocclusions has been shown to affect temporomandibular joint (TMJ) health. However, publications regarding the risk factors that predict negative TMJ outcomes after orthognathic surgery are scarce. OBJECTIVE: Present prospective cohort study was conducted to identify an association between pre-operative dysfunctional/parafunctional oral habits and the presence of TMD symptoms after orthognathic surgery. METHOD: We included 237 patients undergoing orthodontics and surgical treatment for malocclusions associated with dentofacial deformities within the Department of Oral and Maxillofacial Surgery of the University of Lille. Their parafunctional and dysfunctional oral habits were recorded through clinical examination along with the presence of TMD symptoms before and after the surgery. According to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) classification, the TMD symptoms studied were myalgia, arthralgia, disc displacement with or without reduction. RESULTS: Multivariate analysis revealed significant associations among bruxism (odds ratio [OR] 3.17 [1.066; 9.432]), lingual interposition (OR 4.241 [1.351; 13.313]), as well as primary swallowing (OR 3.54 [1.225; 10.234]) and the presence of postoperative symptoms of myalgia. Moreover, a significant association was observed between the presence of any dysfunctional oral habit and postoperative disc displacement with reduction (OR 4.611 [1.249; 17.021]). CONCLUSION: Bruxism and dysfunctional oral habits were shown to be risk factors for the presence of TMD symptoms also after combined orthodontic and surgical treatment. Treating such habits before orthognathic surgery should help prevent TMD.

The Masseter Muscle and Its Role in Facial Contouring, Aging, and Quality of Life: A Literature Review.

BACKGROUND: Masseter muscle hypertrophy manifests itself as enlargement of the masseter muscle. It can be associated with a square-angled lower face, pain, dental attrition, maxillary and mandibular bone resorption, and accelerated aging process of the lower face. The objective of this study was to assess the efficacy and safety of botulinum toxin type A in contouring the masseter and its impact on quality of life and the aging process of the lower face, and its role in full face rejuvenation. METHODS: A PubMed search was conducted for articles on masseter treatment with botulinum toxin type A, masseter muscle hypertrophy, and the aging process of the lower face. Key studies are reviewed and findings are summarized. RESULTS: Botulinum toxin type A can be injected into the lower posterior aspect of the masseter muscle. Treatment decreases muscle bulk and reshapes the lower face. Furthermore, patient quality-of-life measures, including pain and symptoms of grinding and clenching, are improved. Treatment can decrease shear stress on maxillary and mandibular bones and can possibly prevent tooth loss and progressive bone resorption of the lower face. Adverse effects are minimal and short lasting. CONCLUSIONS: Botulinum toxin type A is a safe and effective treatment of masseter hypertrophy. The treatment results in improvement of functionality and cosmesis, and restoration of facial harmony.

Association between self-reported bruxism and anger and frustration.

BACKGROUND: Even though bruxism has been shown to be associated with several psychological factors, few studies have been performed on its relationships with anger and frustration. OBJECTIVE: This study aimed to determine the association between self-reported awake and sleep bruxism and anger and frustration. METHODS: In this longitudinal observational study, 55 healthy adult participants with "possible" bruxism reported their experienced level of bruxism and several psychosocial factors and lifestyle factors for 28 consecutive days using a personal logbook. The logbook consisted of a daily diary and a weekly questionnaire composed of Dutch versions of validated questionnaires. The primary outcome data were analysed using multiple regression models. RESULTS: An increase in SB of 1 unit (on a scale ranging from 1 to 10) was associated with an increase in the anger-scale of 0.03 units, and the frustration-scale of 0.04 units. However, the random intercepts were 0.22 for anger and 0.19 for frustration, meaning that there were major differences between individuals. For awake bruxism (AB), the effects were an increase of 0.04 for anger with a random intercept of 0.21 and an increase of 0.03 for frustration with a random intercept of 0.06. The effects of anger and frustration on both SB and AB were not statistically significant. CONCLUSION: The association between anger and frustration and self-reported bruxism is small on group level. In individual cases, anger and frustration and self-reported bruxism may be co-existent.