Assessment of electromyography in evaluating masseter muscle activity in oral submucous fibrosis with different treatment modalities: a systematic review

Electromyography (EMG) is used for the measurement of muscle activity to characterize the nature of muscle contraction in Oral submucous fibrosis (OSMF). Aim: To assess the efficacy of EMG in evaluating masseter muscle activity in the management of OSMF. This review identified 73 records from standard databases which were rigorously screened with eligibility criteria and 3 clinical studies were identified based on our inclusion criteria. The quality of included studies was assessed by the PEDro scale and data was synthesized with detailed characterization. The Risk of Bias assessment among studies was done using the ROBINS-I tool and a meta-analysis could not be done due to high clinical heterogeneity. Our result recommends that EMG be used as an objective prognosis assessment tool by quantifying the management of OSMF irrespective of the intervention applied. However, it is not to be considered the gold standard as of now with limited data pooled and needs to be further assessed with clinical trials. EMG can be advocated as a reliable adjunct assessment for measuring the interventional outcome of OSMF irrespective of treatment modalities.

La electromiografía se ha utilizado para medir la actividad muscular y caracterizar la naturaleza de la contracción muscular. Nuestra revisión sistemática tuvo como objetivo evaluar la eficacia de EMG en la evaluación de la actividad del músculo masetero en el manejo de OSMF. Esta revisión identificó 73 registros de bases de datos estándar que se revisaron rigurosamente con criterios de elegibilidad y se identificaron 3 estudios clínicos según nuestros criterios de inclusión. La calidad de los estudios incluidos se evaluó mediante la implementación de la escala PEDro y los datos se sintetizaron con una caracterización detallada. La evaluación del riesgo de sesgo entre los estudios se realizó mediante la herramienta ROBINS-I y no se pudo realizar un metanálisis debido a la alta heterogeneidad clínica. Nuestro resultado recomienda que la EMG podría utilizarse como una herramienta objetiva de evaluación del pronóstico mediante la cuantificación en el manejo de OSMF independientemente de la intervención aplicada. Sin embargo, no debe considerarse el estándar de oro a partir de ahora con datos agrupados limitados, y debe volver a evaluarse en el futuro después de la disponibilidad de ensayos clínicos extensos. A partir de ahora, la EMG se puede recomendar como un equipo de evaluación complementario confiable para medir el resultado de la intervención de la fibrosis submucosa oral, independientemente de las modalidades de tratamiento.

Confiabilidade teste-reteste de um protocolo de coleta do sinal eletromiográfico do músculo masseter em indivíduos com disfunção temporomandibular / Test-retest reliability of a protocol for recording the electromyographic signal from the masseter muscle on patients with temporomandibular disorders

Introdução: A eletromiografia (EMG) tem sido utilizada para avaliar alterações no sistema mastigatório proporcionada pela disfunção temporomandibular (DTM). Objetivos: Verificar a confiabilidade teste-reteste de um protocolo de coleta do sinal EMG do músculo masseter em indivíduos com DTM. Métodos: Estudo transversal composto por 20 indivíduos com DTM. Os testes foram realizados em duas sessões com 7 dias de intervalo. O sinal EMG foi avaliado pelas variáveis integral (iEMG) e a raiz quadrada da média do sinal (RMS). Resultados: Na análise intradia a confiabilidade para o RMS (ICC2,k: 0.85 a 0.96 ) e iEMG ICC2,k: 0.85 a 0.95) foi excelente, enquanto que a confiabilidade teste/reteste foi pobre para ambas as variáveis RMS (ICC2,1: 0.03 a 0.29) e iEMG (ICC2,1: 0.08 a 0.39). Conclusões: O protocolo de coleta do sinal EMG do músculo masseter em indivíduos com DTM demonstrou que os dados são reprodutíveis somente na mesma sessão de coletas enquanto que, para coletas em dias alternados a confiabilidade foi pobre.

Introduction: Electromyography (EMG) has been used to assess alterations in the masticatory system caused by temporomandybular disorders (TMD). Objectives: The aim of this study was to verify the test-retest reliability of a protocol for recording the EMG signal from masseter muscle in TMD patients. Methods: This is a cross-sectional study comprising 20 individuals with TMD. Tests were performed in two sessions 7 days apart. The EMG signal was evaluated by the variables integral (iEMG) and the root mean square of the signal (RMS). Results: In the intraday analysis the reliability for the RMS (ICC2,k: 0.85 to 0.96) and iEMG (ICC2,k: 0.85 to 0.95) was excellent, while the test/retest reliability was poor for both RMS (ICC2,1: 0.03 to 0.29) and iEMG (ICC2,1: 0.08 to 0.39) variables. Conclusions: The protocol for collecting the EMG signal from the masseter muscle in an individual with TMD demonstrated that the data are reproducible only in the same recording session, whereas for c recording on alternate days, the reliability was poor.

Do myofascial trigger points in masseter muscles affect the symptoms of disc displacement with reduction? A cross-sectional study

SUMMARY OBJECTIVE: The aim of this study was to demonstrate the effect of myofascial pain with referral from the trigger points in the masseter muscles on the clinical symptoms and functional limitations of the temporomandibular joint in participants with disc displacement with reduction. METHODS: This prospective, cross-sectional study recruited participants aged 18-45 years with disc displacement with reduction with/without myofascial pain with referral in the masseter muscles based on the inclusion criteria. Maximum mouth opening and the presence of probable awake bruxism were assessed. The "Graded Chronic Pain Scale version 2.0" and "Jaw Function Limitation Scale-8" were used to evaluate Diagnostic Criteria for Temporomandibular Disorders Axis II. Pain levels were measured using the Visual Analog Scale. RESULTS: A comparison between the disc displacement with reduction and disc displacement with reduction+myofascial pain with referral groups revealed statistically significant differences in Visual Analog Scale (p<0.001), the presence of awake bruxism (p=0.038), and Graded Chronic Pain Scale version 2.0 (p=0.010). However, no statistically significant difference was observed between the two groups concerning maximum mouth opening and Jaw Function Limitation Scale-8. CONCLUSION: Participants with both disc displacement with reduction and myofascial pain with referral in the masseter muscle exhibited higher pain intensity, a higher prevalence of awake bruxism, and increased pain-related disability compared to those with disc displacement with reduction alone.

Evaluating the use of wearables in the masseter and temporal muscles: a scoping review protocol / Avaliação do uso de tecnologias vestíveis nos músculos masseter e temporal: um protocolo de revisão de escopo

ABSTRACT Purpose: to develop a scoping review protocol that seeks to identify which procedures and for what purpose wearables available in the literature are being used on the masseter and temporal muscles. Methods: the approach recommended by The Joanna Briggs Institute and the PRISMA-P guidelines, will follow. Databases to be searched include PubMed, Cochrane Library, LILACS, Scopus, Web of Science, Embase and grey literature. In the first step, two reviewers will independently evaluate the articles by titles and abstracts, then, a full review of the selected articles will be performed according to the inclusion and exclusion criteria. Any uncertainties or differences of opinion will be discussed for consensus. Articles published without date or language restrictions will be included. All components will be presented in tables and flow charts. In addition, a narrative summary of each component will be included for further details. Final Considerations: this protocol will present the general state of the literature on the use of wearables in masseter and temporal masticatory muscles.

RESUMO Objetivo: desenvolver um protocolo de revisão de escopo que busque identificar quais procedimentos e com que finalidade as tecnologias vestíveis disponíveis na literatura estão sendo usadas nos músculos masseter e temporal. Métodos: seguirá a abordagem recomendada pelo The Joanna Briggs Institute e as diretrizes PRISMA-P. As bases de dados a serem pesquisadas incluem PubMed, Cochrane Library, LILACS, Scopus, Web of Science, Embase e literatura cinzenta. Em uma primeira etapa, dois revisores, de forma independente, avaliarão os artigos pelos títulos e resumos, em seguida, será realizada a revisão na íntegra dos artigos selecionados de acordo com os critérios de inclusão e exclusão. Quaisquer incertezas ou diferenças de opinião serão discutidas para consenso. Serão incluídos artigos publicados sem restrição de data e idioma. Todos os componentes serão apresentados em tabelas e fluxogramas. Além disso, um resumo narrativo de cada componente será incluído para mais detalhes. Considerações finais: este protocolo irá apresentar o estado geral da literatura acerca do uso das tecnologias vestíveis na musculatura mastigatória de masseter e temporal.

Trigger point dry needling increases masseter muscle oxygenation in patients with temporomandibular disorder

Abstract Background: Temporomandibular disorder (TMD) is an umbrella term encompassing various clinical complaints involving the temporomandibular joints, masticatory muscles, and/or associated orofacial structures. Myogenous TMDs are the most frequent cause of chronic orofacial pain. Musculoskeletal pain is commonly associated with myofascial trigger points (MTPs), for which dry needling (DN) is a routine treatment. Objective: To investigate muscle oxygenation and pain immediately after DN application on an MTP in the masseter muscle of patients with myogenous TMDs. Methodology: Masseter muscle oxygen tissue saturation indices (TSI%) were assessed by near-infrared spectroscopy (NIRS) pre- and post-interventions by a randomized, controlled, double-blind, crossover DN/Sham clinical trial (primary outcome). Pain was investigated by the visual analog scale (VAS). In total, 32 individuals aged from 18 to 37 years who were diagnosed with myogenous TMD and myofascial trigger points in their masseter muscles participated in this study. Relative deltas for the studied variables were calculated. Data normality was tested using the Shapiro-Wilk test. According to their distribution, data were analyzed by two-way ANOVA and the Student's t-, and Mann-Whitney tests. Statistical analyses were performed using Prism® 5.0 (GraphPad, USA). Results: We found a significant difference (2,108% vs. 0,142%) between masseter muscle TSI% deltas after the DN and Sham interventions, respectively (n=24). We only evaluated women since men refused to follow NIRS procedures. Pain increased immediately after DN (n=32, 8 men), in comparison to Sham delta VAS. Conclusion: These findings show an increase in tissue oxygen saturation in the evaluated sample immediately after the DN intervention on the MTP of patients' masseter muscle. Pain may have increased immediately after DN due to the needling procedure.

Masseter muscle flap for reconstruction of intra-oral defects in patients with early cancer of posterior-inferior parts of the oral cavity / Retalho do músculo masseter para reconstrução de defeitos intraorais em pacientes com câncer inicial de partes póstero‐inferiores da cavidade oral

Abstract Introduction Early carcinomas of the oral cavity in the posterior-inferior regions poses a challenge for reconstruction due to the lack of muscle support underneath and the limited space available to use some of the frequently-used flaps. Objective This study was done to evaluate the efficacy of the superiorly based masseter muscle flap in reconstruction of intra-oral post- ablation defects in patients with early oral carcinoma of the posterior-inferior part of the oral cavity. Methods A superiorly based masseter muscle flap were used to reconstruct the post-surgical intra- oral defect in 60 patients with early squamous cell carcinoma (T < 4 cm) of the posterior-inferior part of the oral cavity. The patients were followed up at 1-week and 1-month postoperatively to check for flap viability, complications, change in mouth opening and deviation of the mandible on mouth opening. To rule out any recurrence in the oral cavity masseter flaps, the patients were followed up for 1 year. Results The flap was viable in all patients and underwent mucosalization. 7/60 patients had postoperative infections, while 2/60 patients developed an oro-cutaneous fistula which required a secondary corrective procedure. The mean ± standard deviation of change in mouth opening at 1 week postoperatively was +1.917 ± 3.36 mm, which increased to +2.633 ± 2.95 mm at 1 month after surgery. The Friedman test revealed that there was a statistically significant change in mouth opening from preoperative period to the1 week and 1 month postoperative periods (p = 0.000). Female patients showed better improvement in mouth opening postoperatively. The ipsilateral deviation of the mandible on mouth opening was between 0-5 mm in 39 patients, 5-10 mm in 17 patients and more than 10 mm in 4 patients. There were no recurrences noted in the masseter flaps used. Conclusion The study infers that the superiorly based masseter muscle flap is a reliable method for reconstruction in early oral cancer patients yielding good functional results and acceptable cosmesis with nominal postoperative complications.

Resumo Introdução Os carcinomas iniciais da cavidade oral nas regiões póstero‐inferiores representam um desafio para a reconstrução devido à falta de suporte muscular abaixo da região e ao espaço limitado disponível para o uso de alguns dos retalhos mais empregados. Objetivo Avaliar a eficácia do retalho do músculo masseter de base superior na reconstrução de defeitos intraorais pós‐ablação em pacientes com carcinoma oral inicial da parte póstero‐inferior da cavidade oral. Método Um retalho do músculo masseter de base superior foi usado para reconstruir o defeito intraoral pós‐cirúrgico em 60 pacientes com carcinoma espinocelular inicial (T < 4 cm) localizado na parte póstero‐inferior da cavidade oral. Os pacientes foram acompanhados após uma semana e um mês de pós‐operatório para verificação da viabilidade do retalho, complicações, alteração na abertura bucal e desvio da mandíbula na abertura bucal. Para descartar recidiva nos retalhos do masseter, os pacientes foram acompanhados por um ano. Resultados O retalho foi viável em todos os pacientes e foi submetido à mucolização; 7/60 pacientes tiveram infecções pós‐operatórias, enquanto 2/60 pacientes desenvolveram uma fístula orocutânea que exigiu um procedimento corretivo secundário. A média ± desvio‐padrão da alteração na abertura da boca em uma semana de pós‐operatório foi + 1,917 ± 3,36 mm, que aumentou para + 2,633 ± 2,95 mm em um mês de pós‐operatório. O teste de Friedman revelou que houve uma alteração estatisticamente significante na abertura da boca do período pré‐operatório para os períodos de uma semana e um mês de pós‐operatório (p = 0,000). Pacientes do sexo feminino apresentaram maior melhoria na abertura da boca no pós‐operatório. O desvio ipsilateral da mandíbula na abertura da boca ficou entre 0 a 5 mm em 39 pacientes, 5 a 10 mm em 17 pacientes e mais de 10 mm em 4 pacientes. Não foram observadas recidivas nos retalhos de masseter usados. Conclusão O retalho do músculo masseter com base superior é um método confiável para reconstrução em casos de câncer oral inicial, produz bons resultados funcionais e resultados cosméticos aceitáveis com complicações pós‐operatórias insignificantes.

Variação da atividade elétrica entre o repouso e a máxima contração voluntária dos músculos masseteres em homens adultos / Variation of electrical activity between rest and maximum voluntary contraction of masseter muscles in adult men / Variación de la actividad eléctrica entre el descanso y la contracción voluntaria máxima de los músculos maseteros en hombres adultos

Introdução: A eletromiografia de superfície (EMGs) é um exame objetivo, indolor, não invasivo e de fácil aplicação utilizado para avaliar as atividades elétricas de determinado músculo ou grupo muscular durante a máxima contração voluntária, repouso e dinâmica funcional. Objetivo: Comparar a variação do potencial elétrico dos músculos masseteres entre o repouso e máxima contração voluntária em indivíduos com faixas etárias diferentes. Método: A pesquisa foi aprovada em comitê de ética e executada na Clínica Escola do Departamento de Fonoaudiologia da Universidade Federal de Sergipe obedecendo aos rigores éticos e de biossegurança. A amostra foi composta por 26 adultos sem queixas orofaciais, sexo masculino e idade variando entre 26 e 42 anos, divididos em Grupo 1 e Grupo 2, os quais assinaram um termo de consentimento livre e esclarecido concordando com a participação na pesquisa. Os voluntários foram submetidos à avaliação eletromiográfica dos músculos masseteres durante o repouso e máxima contração voluntária. Resultados: Houve uma diminuição da atividade elétrica do masseter quando se comparou o G1 com o G2, porém não foi observada uma linearidade desse declínio ao analisar o universo estudado. Por isso, deve-se levar em consideração que o envelhecimento é um processo fisiológico particular de cada ser, sendo influenciado por múltiplos fatores intrínsecos e extrínsecos ao organismo. Observou-se, também, que no repouso nenhum indivíduo teve absolutamente 0 nos seus registros eletromiográficos, caracterizando um estado basal de atividade elétrica para garantia do tônus. Conclusão: Foi verificado que os voluntários com 30 anos ou mais apresentaram um declínio nos potenciais mioelétricos e, possivelmente, um déficit de força associado.

Introduction: Surface electromyography (EMGs) is an objective, painless, non-invasive and easily applied test used to assess the electrical activities of a particular muscle or muscle group during maximum voluntary contraction, rest and functional dynamics. Objective: Compare the variation in the electrical potential of the masseter muscles between rest and maximum voluntary contraction in individuals with different age groups. Method: The research was approved by the ethics committee and carried out at the Clínica Escola of the department of Speech, Language and Hearing Sciences at the Federal University of Sergipe, obeying ethical and biosafety rigors. The sample consisted of 26 adults without orofacial complaints, male with age from 26 to 42 years old, divided into Group 1 and Group 2, who signed a consent form agreeing to participate in the research. The volunteers underwent electromyographic evaluation of the masseter muscles during rest and maximum voluntary contraction. Results: There was a decrease in the electrical activity of the masseter when comparing G1 to G2; however, there was no linearity of this decline when analyzing the universe studied. Therefore, it must be taken into account that aging is a particular physiological process of each individual, being influenced by multiple factors, intrinsic and extrinsic to the organism. It was also observed at rest, no individual had absolutely 0 in their electromyographic records, characterizing a baseline state of electrical activity to guarantee tone. Conclusion: It was found that volunteers aged 30 years or more showed a decline in myoelectric potentials and possibly an associated strength deficit.

Introducción: Electromiografía de superficie (EMG) es una prueba objetiva, indolora, no invasiva y de fácil aplicación que se utiliza para evaluar actividades eléctricas de un músculo o grupo muscular en particular durante la contracción voluntaria máxima, el reposo y la dinámica funcional. Objetivo: Comparar la variación del potencial eléctrico de los maseteros entre reposo y contracción voluntaria máxima en individuos de diferentes grupos de edad. Método: La investigación fue aprobada por el comité de ética y realizada en la Clínica Escola del departamento de logopedia de la Universidad Federal de Sergipe obedeciendo rigores éticos y de bioseguridad. La muestra estuvo conformada por 26 adultos sin quejas orofaciales, varones y edades comprendidas entre 26 y 42 años dividido en Grupo 1 y Grupo 2, quienes firmaron formulario de consentimiento aceptando participar en la investigación. Los voluntarios se sometieron a evaluación electromiográfica de los músculos maseteros durante reposo y la máxima contracción voluntaria. Resultados: Hubo disminución en la actividad eléctrica del masetero cuando se comparó G1 con G2, sin embargo no hubo linealidad de esta disminución al analizar el universo estudiado. Por tanto, hay que tener en cuenta que el envejecimiento es proceso fisiológico particular de cada ser, siendo influenciado por múltiples factores intrínsecos y extrínsecos al organismo. También se observó que en reposo ningún individuo tenía absolutamente 0 en sus registros electromiográficos, caracterizando estado basal de actividad eléctrica para garantizar el tono. Conclusión: Se encontró que los voluntarios de 30 años o más mostraron una disminución en los potenciales mioeléctricos y posiblemente un déficit de fuerza asociado.

Intramuscular hemangioma of the masseter muscle:a case report

Background - Intramuscular hemangiomas are benign vascular tumours that most frequently occur in the trunk and extremities.They constitute about <1% of all hemangiomas, only 10%–20% have been found to arise in the head and neck region, and 36% of cases involving masseter muscle.They usually present as gradually enlarging soft-tissue mass with or without pain. They are located deep within the muscle, hence rarely exhibit clinical signs or symptoms such as bruits, thrills, pulsation which are suggestive of vascular origin. Due to their rare occurrence, unique location they are often confused with other soft-tissue pathologies such as parotid swelling or other muscular lesions. Case report - 21 year old male came with complaints of swelling and pain over the left cheek for past 6 months which was insidious in onset and non progressive.Patient did not have any history of trauma or increased salivation.On examination swelling of about 2*2 cm over the left cheek,well defined,non tender,soft in consistency.There was no pulsation,bruits or palpable thrill.There was no compressibility and the overlying skin was normal.There was no facial nerve involvement and parotid duct orifice was normal. Conclusion - The possibility of an Intramuscular hemangioma of the masseter muscle should be included in the differential diagnosis of any intra-masseteric lesion. Appropriate radiologic examinations, especially MRI, can enhance accurate preoperative diagnosis; the treatment of choice should be individualized in view of the clinical status of the patient.

Modelo lineal vs. vectorial: estimación del movimiento mandibular y trabajo mecánico / Linear vs. vector model: estimation of mandible motion and mechanical work

Objetivo: Determinar los momentos de fuerza del haz superficial del masetero (SMH) obtenidos por modelos lineal y vectorial. Métodos: Investigación comparati-va in silico. Se obtuvo la fuerza del SMH con dinamó-metro en 12 pacientes varones adultos jóvenes para calcular el momento de la fuerza y trabajo mecánico a través de simulaciones en JAVA+ con NetBeans8.2. La descomposición de la fuerza fue F.cos α(x,y) y F.cos α(x,y,z) en el modelo lineal y vectorial respectivamen-te. Los momentos de fuerza fueron comparados por ANOVA (p<0,05). Resultados: La fuerza del SMH unila-teral obtenida con dinamómetro (2,5±0,1N) no difirió significativamente del modelo lineal (2,6±0,05N), pero difirió (p<0,001) del vectorial: 1,7, 2,2, 4,2N en x,y,z (general 2,7±0,02N). El momento medio de la fuerza en el modelo vectorial fue -17,9, -15,5, +14,3N.m-2, apuntando a la inclinación mandibular en el eje lateral en dirección caudal anterior, movimiento de inclina-ción en el eje lateral en la dirección cráneo-medial, e inclinación en el eje craneal en la dirección lateral-an-terior. El modelo lineal mostró momento de fuerza de 13,5N.m-2 apuntando un movimiento traslacional en dirección caudal-craneal en el eje anterior-posterior y menor trabajo mecánico del SMH (p=0,012). Con-clusión: Los modelos vectoriales son más eficientes proporcionando datos detallados para estimar los momentos de fuerza y el trabajo mecánico del SMH, y deben incluirse en los algoritmos de cálculo utilizados por dinamómetros (AU)

Objective: to determine the moments of force exerted by the superficial masseter head (SMH) obtained through linear models and vector ones. Methods: comparative in silico research. Data of SMH force obtained with dynamometer in 12 young adult male patients was used to calculate the moment of the force and mechanical work through simulations in JAVA+ performed with NetBeans8.2. Force decomposition was F.cos α(x,y) and F.cos α(x,y,z) in the linear and vector model respectively. The moments of force were compared by ANOVA (p<0.05). Results: Dynamometrical unilateral SMH force (2.5±0.1N) did not differ significantly from the linear model (2.6±0.05N), but differed (p<0.001) from the vector model: 1.7, 2.2, 4.2N on x,y,z (overall 2.7±0.02N). The mean moment of the force in the vector model was -17.9, -15.5, +14.3N.m-2, pointing to mandible's inclination on the lateral axis in anterior-caudal direction, inclination movement on the lateral axis in the cranio-medial direction and inclination on the cranial axis in the lateral-anterior direction. The linear model showed a moment of force of 13.5N.m-2 pointing to translational motion on caudal-cranial direction on the anterior-posterior axis and lower SMH mechanical work (p=0,012). Conclusion: Vector models are more efficient to provide detailed data to estimate the moments of force and mechanical work of SMH and should be included in the calculation algorithms used by dynamometers (AU)

Evaluation of Masseter Muscle Dimensions Through Ultrasonography

ABSTRACT: The objective this study was to determine mean values of masseter muscle thickness in male and female, at rest and contraction, in healthy individuals. At first, 102 questionnaires were distributed between students. Thirty patients were selected, 15 male and 15 female, according to the inclusion criteria, excluding all individuals with symptoms of temporo-mandibular dysfunction or syndromes with craniofacial disorders. Masseter muscle thickness was determined bilaterally, at rest and contraction. As a reference point for the measurement of thickness (axial plane), the posterior prolon gation of the labial commissure was used. Normality values of the masseter muscle in females were 11.75 ± 1,14 mm in contraction and 10.19 ± 1.04 mm in relaxation; and in the male were 13.95 ± 1.62 mm in contraction and 11.64 mm ± 1.68 mm in relaxation. The results obtained are in agreement with those described in the literature. Demonstrating the accuracy and reproductibility of the ultrasound if a protocol is applied, mainly aimed at controlling the pressure applied by the transducer.

RESUMEN: El objetivo de este estudio fue determinar los valores medios del grosor del músculo masetero, en reposo y contracción, en hombres y mujeres sanos. Inicialmente se distribuyeron 102 cuestionarios entre los estudiantes. Se seleccionaron 30 pacientes, 15 hombres y 15 mujeres, según los criterios de inclusión, excluyendo a todos los individuos con síntomas de disfunción temporo-mandibular o síndromes con alteraciones craneofaciales. El grosor del músculo masetero se determinó de forma bilateral, en reposo y contracción. Como punto de referencia para la medición del espesor (plano axial), la prolongación posterior de la comisura labial. Los valores de normalidad del músculo masetero en las mujeres fue de 11,75 ± 1,14 mm en contracción y 10,19 ± 1,04 mm en relajación; y en los varones 13,95 ± 1,62 mm en contracción y 11,64 mm ± 1,68 mm en relajación. Los resultados obtenidos coinciden con los descritos en la literatura, señalando la precisión y reproducibilidad del ultrasonido si se aplica un protocolo, principalmente dirigido a controlar la presión aplicada por el transductor.

Revisión sistemática de la literatura sobre la evaluación del proceso de la masticación / Systematic Review Of The Literature On The Evaluation Of The Chewing Process

El objetivo del presente estudio fue presentar una revisión sistemática de la literatura relacionada con los estudios que aborden los métodos de evaluación de la masticación y sus características principales. Como estrategia de investigación se realizó en las bases de datos PubMed, Web Of Science, Medline, SciELO y Lilacs desde 2006 al 2020. Como criterios de selección se escogieron todos los estudios disponibles, sin restricción de idioma; de los últimos 14 años; cuyos participantes no presentaron alteraciones neurológicas ni psiquiátricas. Fueron analizados a partir de su relación con el objeto del presente estudio. Las palabras clave utilizadas en la búsqueda de los artículos fueron identificados en los Descriptores en Ciencias de la Salud (DEDS) siendo las siguientes: "Evaluation", "Mastication", "Masticatory Muscles", "Masseter Muscle" y "Temporal Muscle". Utilizando también OR y AND como operadores lógicos. Se encontró 1311 estudios en las bases de datos investigadas, después de la revisión fueron eliminados 1278 y elegidos 33 artículos; y considerándose sólo 21 artículos según criterios de selección y objetivo. Todos los artículos revisados obtuvieron un alto grado de evidencia (nivel I) luego de realizar una evaluación crítica de la evidencia científica, determinando que todos los artículos evaluados fueron catalogados como estudios clínicos aleatorizados y con diseños experimentales. Siendo excluidos los estudios longitudinales, con individuos con patologías. Se concluye que el método que se utiliza mayormente es la evaluación clínica fonoaudiológica, mediante observación y palpación de musculatura orofacial, seguido de electromiografía de superficie, electrognatografía y la escala analógica visual para la saciedad. Las características observadas fueron, número de ciclos de masticación, velocidad de la masticación, porcentaje de actividad muscular eléctrica, fuerza muscular, tipo de masticación según el lado de preferencia de masticación, eficiencia masticatoria y tipología facial.

The objective of the present study was to present a systematic review of the literature related to studies that address chewing evaluation methods and their main characteristics. As a research strategy, it was carried out in the PubMed, Web Of Science, Medline, SciELO and Lilacs databases from 2006 to 2020. All available studies were chosen as selection criteria, without language restriction; of the last 14 years; whose participants did not present neurological or psychiatric alterations. They were analyzed based on their relationship with the object of the present study. The keywords used in the search for the articles were identified in the Health Sciences Descriptors (DEDS) being the following: "Evaluation", "Mastication", "Masticatory Muscles", "Masseter Muscle" and "Temporal Muscle". Also using OR and AND as logical operators. 1311 studies were found in the investigated databases, after the review 1278 were eliminated and 33 articles were chosen; and considering only 21 articles according to selection and objective criteria. All the articles reviewed obtained a high degree of evidence (level I) after making a critical evaluation of the scientific evidence, determining that all the articles evaluated were classified as randomized clinical studies with experimental designs. Longitudinal studies with individuals with pathologies being excluded. It is concluded that the method most used is the speech therapy clinical evaluation, by observation and palpation of the orofacial muscles, followed by surface electromyography, electrognatography and the visual analog scale for satiety. The observed characteristics were, number of chewing cycles, chewing speed, percentage of electrical muscle activity, muscle strength, chewing type according to chewing preference side, chewing efficiency and facial typology.

The use of photobiomodulation for the muscles of head and neck: an integrative review / O uso da fotobiomodulação nos músculos da cabeça e pescoço: revisão integrativa da literatura

ABSTRACT Purpose To carry out an integrative review of the literature on the use of photobiomodulation (PBM) for the head and neck muscles. Research strategy The research took place between June/2019 and March/2021, in the following databases: PubMed, Scopus, Web of Science, LILACS, and SciELO. The MeSH used were Low-Level Light Therapy, Phototherapy, Masseter Muscle, Masticatory Muscles, Tongue, Palate, Mouth, Neck Muscles, and Facial Muscles in English and Portuguese. No limitation was imposed on the year and language of publication. Selection criteria studies that answered the guiding question: what is the use of photobiomodulation to the head and neck muscles?. Results 2857 articles were found, of which 102 were selected for full reading, 52 of those were excluded, giving a total of 50 articles included. The included publications date from 2003 to 2020. Brazil was the country that most published on the topic. With regard to the objectives, 82% of the studies aimed to investigate the analgesic effect of PBM, of these, 50% were related to articular or muscular temporomandibular disorders (TMD). The heterogeneity of the studies makes it impossible to define the dose protocols. Conclusion PBM has been applied to the head and neck muscles mainly for the treatment of pain caused by TMD. There is no treatment protocol to define the doses to be used, due the heterogeneity of the methodologies applied and results found.

RESUMO Objetivos realizar uma revisão integrativa da literatura sobre o uso da fotobiomodulação nos músculos de cabeça e pescoço. Estratégia de pesquisa As buscar foram realizadas nas bases de dados: PubMed, Scopus, Web of Science, LILACS e SciELO. A pesquisa ocorreu entre junho de 2019 e março de 2021. Os descritores utilizados foram Terapia com Luz de Baixa Intensidade, Fototerapia, Músculo Masseter, Músculos Mastigatórios, Língua, Palato, Boca, Pescoço, Músculos do Pescoço, Músculos Faciais e seus respectivos termos em inglês. Não houve limitação de ano de publicação e idioma. Critérios de seleção estudos que respondessem a pergunta norteadora: qual o uso da fotobiomodulação na musculatura de cabeça e pescoço?. Resultados Foram encontrados 2857 artigos, sendo selecionados 102 para leitura completa, dos quais 52 foram excluídos, totalizando 50 artigos incluídos. As publicações incluídas datam de 2003 a 2020. O Brasil foi o país que mais publicou sobre o tema. Quanto aos objetivos, 82% dos estudos pesquisaram o efeito analgésico da fotobiomodulação, e desses, 50% eram relacionados à disfunção temporomandibular (DTM) articular ou muscular. A heterogeneidade dos estudos impossibilita a definição de protocolos dosimétricos. Conclusão A fotobiomodulação tem sido utilizada na musculatura de cabeça e pescoço principalmente para o tratamento da dor proveniente de DTM. Não existe um protocolo de aplicação que defina os parâmetros dosimétricos a serem utilizados, devido a heterogeneidade das metodologias e dos resultados encontrados.

Avaliação da alteração de músculos mastigatórios em pacientes com anquilose temporomandibular e o impacto da fonoterapia pós-operatória na recuperação destes pacientes / Evaluation of change of mastigatory muscles in patients with temporomandibular ankillosis and the impact of postoperative phonotherapy on recovery of these patients

A anquilose temporomandibular (AQTM) é uma condição rara caracterizada pela restrição da abertura mandibular, que impacta negativamente na qualidade de vida destes pacientes. O tratamento cirúrgico tem como objetivo reestabelecer a abertura de boca e, consequentemente, retomar à normalidade a respiração, a mastigação e a fala. A fonoterapia pós-operatória é descrita na prática clínica como uma etapa fundamental no processo de recuperação destes pacientes, pois visa estimular a musculatura facial e, assim, evitar a imobilização prolongada que pode levar à reanquilose. Contudo, poucos trabalhos investigaram a ocorrência de alterações morfofuncionais nos músculos faciais de pacientes com AQTM, bem como investigaram se a fonoterapia pós-operatória de fato influencia no processo de recuperação destes pacientes. O objetivo deste estudo foi avaliar a existência de alteração na área seccional dos músculos mastigatórios masseter e pterigoide medial em pacientes com AQTM e a influência da fonoterapia pós-operatória na recuperação destes pacientes. Foi realizado um estudo retrospectivo envolvendo 39 pacientes com AQTM atendidos no INTO entre janeiro de 2010 e dezembro de 2018, e 54 pacientes controle (sem disfunção da ATM). As principais causas conhecidas de AQTM foram trauma (38,46%) e infecção (17,95%), e a mediana de idade dos pacientes foi de 16 anos. A maioria dos pacientes com AQTM era do sexo masculino (66%), o acometimento unilateral ocorreu em 70,3% dos pacientes e a maior parte dos casos de AQTM foi de natureza óssea (74,3%). As alterações na área seccional dos músculos masseter e pterigoide medial foram avaliadas através de imagens de tomografia computadorizada, sendo observada menor área seccional no plano axial destes músculos em pacientes com AQTM em comparação com pacientes controle. Ao compararmos a área dos músculos masseter e pterigoide medial de pacientes com AQTM (abertura de boca < 30mm) com a de pacientes recuperados após o tratamento (abertura de boca > 30mm), verificamos um aumento da área seccional deste último grupo. Por fim, investigamos a influência da fonoterapia pós-operatória no desfecho do tratamento cirúrgico através dos registros de comparecimento dos pacientes à fonoterapia em seus prontuários. Foi observado que em 76,66% dos procedimentos em que o paciente aderiu à fonoterapia houve um desfecho favorável. Por outro lado, em 95,45% dos procedimentos em que o paciente não aderiu à fonoterapia houve reanquilose. Através do teste exato de Fisher, foi verificado que os pacientes que não aderiram ao tratamento fonoterápico pós-operatório apresentaram maior risco de recidiva da anquilose. Concluímos que os pacientes com AQTM possuem redução da área seccional dos músculos masseter e pterigoide medial e que a fonoterapia pós-operatória é fundamental para o sucesso do tratamento da AQTM

Temporomandibular joint ankylosis (TMJA) is a rare condition characterized by restricted mandibular opening, which has a negative impact on the quality of life of these patients. The surgical treatment aims to reestablish the mouth opening and, consequently, to resume breathing, chewing and speech. Postoperative speech therapy is described in clinical practice as a fundamental step in the recovery process of these patients and it aims to stimulate facial muscles and thus prevent prolonged immobilization that may lead to reankylosis. However, few studies have investigated whether morphofunctional changes occur in the facial muscles of patients with TMJA, as well as whether postoperative speech therapy actually affects patient recovery. The aim of this study was to evaluate changes in the sectional area of the masseter and medial pterygoid muscles of patients with TMJA and to investigate the influence of postoperative speech therapy in the recovery of these patients. We conducted a retrospective study involving 39 TMJA patients treated at INTO between January 2010 and December 2018, and 54 control patients (without TMJ dysfunctions). The main causes of TMJA were trauma (38.46%) and infection (17.95%), and the patients' median age was 16 years. Most patients with TMJA were male (66%), the unilateral involvement occurred in 70.3% of patients and most cases of TMJA were of the bony type (74.3%). Changes in the sectional area of the masseter and medial pterygoid muscles were evaluated by analyzing computed tomography images, and a smaller sectional area in the axial plane of these muscles was observed in patients with TMJA compared to control patients. Comparing the area of the masseter and the medial pterygoid muscles of patients with TMJA (mouth opening ≤30mm) with that of patients recovered after treatment (mouth opening >30mm), we observed an increase in the sectional area of the latter group. Finally, we investigated the influence of the postoperative speech therapy on the outcome of the surgical treatment by looking through the speech therapy attendance reports in the patients' medical records. It was observed that in 76.66% of the procedures in which the patient adhered to speech therapy there was a favorable outcome. On the other hand, in 95,45% of the procedures in which the patient did not adhere to speech therapy, there was reankylosis. Fisher's exact test showed that patients who did not adhere to postoperative speech therapy had a higher risk of ankylosis recurrence. We conclude that patients with TMJA have reduced sectional area of the masseter and medial pterygoid muscles and that postoperative speech therapy is fundamental for successful treatment of TMJA

Effect of medium frequency electrical stimulation on expression of neurotrophin-3 in rat masseter muscle / 上海交通大学学报（医学版）

Objective • To investigate the effect of medium frequency electrical stimulation on the expression of neurotrophin-3(NT-3) in the mandibular protrusion of SD rats. Methods • Sixty male SD rats were randomly divided into three groups (n=20): blank control group, conditioned control group (treated with functional appliance, but without medium frequency electrical stimulation) and experimental group (treated with functional appliance and medium frequency electrical stimulation). Five rats in each group were sacrificed on the 3rd, 7th, 14th and 21st day to prepare the samples of masseter muscle. Immunohistochemistry and quantitative real-time PCR methods were used to detect the protein and mRNA expressions of NT-3 in the masseter muscle of rats. Results • The protein and mRNA expressions of NT-3 were increased firstly and then decreased in the conditioned control group and the experimental group, compared with those in the blank control group. Moreover, the protein and mRNA expressions of NT-3 in the conditioned control group were still higher than those in the blank control group on the 21st day (both P<0.05), while the protein and mRNA expressions of NT-3 in the experimental group almost returned to the normal level on the 21st day. Conclusion • Medium frequency electrical stimulation may accelerate the rate of neuromuscular reconstruction and shorten the time of functional orthopedic therapy in rats.

Succinylcholine Induced Masseter Muscle Spasm during Rapid Sequence Induction in a Pregnant Patient with Kypho- Scoliosis: Case Report

Isolated masseter spasm is a rare entity encountered in patients with neuromuscular disorders and is frequently associated with use of succinylcholine or halogenated inhalational anaesthetic during induction. We present a case of 32-year old primigravida obstetric patient with kypho-scoliosis posted for lower segment caesarean section that developed masseter muscle spasm (MMS) following administration of a standard dose of succinylcholine. The episode resolved spontaneously after 6-7 min without progression to malignant hyperthermia. The report highlights that an event of masseter muscle spasm, though, rarely encountered in life-time practice of an anaesthesiologist, may be successfully managed by maintaining oxygenation and ventilation till the crisis is tided over

Correlation between masseter muscle activity and maximum bite force among various facial divergence pattern / Correlación entre la actividad muscular masetera y la fuerza máxima de mordida entre varios patrones de divergencia facial

Objective: To comparatively assess electromyographic (EMG) activity of masseter muscle and maximum bite force among various facial divergence pattern. To compare bilateral variation therefore derive the clinical importance changes in masseter EMG activity. Materials and Methods: The sample size comprised of 90 subjects, age ranging from 16-25 years. They were further classified under three subgroups-normodivergent, hypodivergent and hyperdivergennt based on the cephalometric values. Tekscan Flexiforce B201H sensor along with the associated software was used to record the bite force. The EMG of the superficial masseter muscle was recorded using Biotech Neurocare 2000 surface electromyography machine. The muscle activity was recorded bilaterally from the superficial masseter. The data obtained were statistically analyzed using ROC curve at p<0.05. Results: The bite force of the Hypodivergent group (571.83N±36.65) was more than the Normodivergent (387.26±27.20) and Hyperdivergent groups (373.21N±29.23). The EMG recording of masseter muscle activity in Hypodivergent group was significantly higher than Normodivergent and Hyperdivergent groups. (p-value= <0.01). A significant correlation existed between masseter activity and bite force. Conclusion: The bite force of Hypodivergent jaw base individuals is highest followed by Normodivergent and least in Hyperdivergent individuals.The strong correlation between the muscular activity and the bite force is definitely a contributor to the anchorage value during treatment by fixed Orthodontics.

Objetivo: evaluar comparativamente la actividad electromiográfica (EMG) del músculo masetero y la fuerza de mordida máxima entre varios patrones de divergencia facial. Para comparar la variación bilateral, por lo tanto, derive la importancia clínica de los cambios en la actividad EMG del masetero. Materiales y métodos: El tamaño de la muestra comprende 90 sujetos, con edades comprendidas entre 16 y 25 años. Además, se clasificaron en tres subgrupos: normodivergente, hipodivergente e hiperdivergénico según los valores cefalométricos. Se usó el sensor Tekscan Flexiforce B201H junto con el software asociado para registrar la fuerza de mordida. La EMG del músculo masetero superficial se registró utilizando la máquina de electromiografía de superficie Biotech Neurocare 2000. La actividad muscular se registró bilateralmente a partir del masetero superficial. Los datos obtenidos se analizaron estadísticamente utilizando la curva ROC a p<0,05. Resultados: la fuerza de mordida del grupo hipodivergente (571.83N±36.65) fue mayor que la de los grupos normodivergentes (387.26±27.20) y los hiperdivergentes (373.21N±29.23). El registro EMG de la actividad muscular masetera en el grupo hipodivergente fue significativamente más alto que en los grupos normodivergente e hiperdivergente. (valor de p=<0.01). Existía una correlación significativa entre la actividad del masetero y la fuerza de mordida. Conclusión: la fuerza de mordedura de los individuos hipodivergentes de la mandíbula es más alta seguida por la de Normodivergent y menos en los individuos hiperdivergentes. La fuerte correlación entre la actividad muscular y la fuerza de mordedura definitivamente contribuye al valor de anclaje durante el tratamiento con ortodoncia fija.

Intramasseteric schwannoma treated with facelift incision and retrograde facial nerve dissection

Schwannoma is a slow-growing, well-demarcated, benign soft tissue tumor of the peripheral nerve sheath. It commonly develops in the head and neck region, usually in the parapharyngeal space. In this case, a 42-year-old woman visited the outpatient department to manage a painless mass on her left cheek. She had no history of concern and no neurological symptoms were observed. In the enhanced computed tomography scan, a 2.8 × 2.8 × 1.8 cm, heterogeneously enhanced tumor was detected in the left masseter muscle. A tumor resection under general anesthesia was planned. For the resection, a facelift incision was chosen; branches of the facial nerve were identified and retrogradely dissected. A well-marginated, yellowish, solid mass was found in the left masseter muscle. The mass was excised and given a histopathological diagnosis of schwannoma. A definite diagnosis of schwannoma, originating in the masseter muscle, is difficult to arrive at with radiographic findings alone; it is often misdiagnosed as intramuscular hemangioma. Histopathological examinations, including fine-needle aspiration or histological biopsy after surgery, are necessary. Using a facelift incision with retrograde facial nerve dissection, tumor resection in an intramasseteric lesion can be performed efficiently, without nerve damage, or leaving conspicuous scars on the face.

Differences in Pain Threshold Values of Masseter and Temporalis Muscles Before and After Mastication

Abstract Objective: To analyze the differences in the pain thresholds of the masseter and temporalis muscles before and after chewing at the 5th and 10th minutes. Material and Methods: In this cross-sectional study, the pain thresholds of the muscles in both sides of 43 non-TMD subjects were measured using a digital algometer before and after chewing the bubble gum Xylitol for 5 and 10 min. The values of the muscles before and after mastication at the 5th and 10th were analyzed using Repeated ANOVA. A difference in the values between the left and right sides of the muscles were analyzed using independent t-test, and among the age groups using one-way ANOVA. Results: Average pain threshold values were 1.76 and 1.93 KgF/cm2 for the masseter and temporalis muscles. ANOVA tests indicated significant differences in the values of the muscles before and after mastication at the 5th and 10th min (p=0.000 vs. p<0.001). The differences in the values between the left and right sides of the muscles (p>0.05) and among the age groups (p>0.05) showed no significant difference. However, the values between temporalis and masseter and the values between men and women for each session revealed a significant difference (p<0.05) Conclusion: The masseter and temporalis pain threshold values were reduced 10 min after chewing. The values in both sides of the masseter and temporalis muscles and in different age groups were the same. The temporal muscle and men showed a higher pain threshold than the masseter muscle and women, respectively.

Evaluation measure of 3d volumetry of masseter hypertrophy: association with modalities of imaging / Avaliação de medidas volumétricas 3D da hipertrofia massetérica em dois casos: associação com modalidades de imagem

Abstract Masseteric hypertrophy is a benign condition, asymptomatic and rare, characterized by the excessive development of the masseter muscle, which usually results in aesthetic complaints. The imaging exams for differential diagnosis of pathologies in the parotid-masseteric region is always recommended. This work aims the imaging characterization of masseteric hypertrophy through the report of two clinical cases combining different imaging modalities: panoramic radiography, magnetic resonance imaging, computed tomography, ultrasonography and 3D volumetry. Two male subjects with no family history of masseteric hypertrophy were referred to a diagnostic center in dentomaxillofacial radiology due to an increase in bilateral facial volume in the masseteric region. Images of the panoramic radiography showed an increase of the bilateral mandibular angle in both cases. Using computerized tomography, bilateral masseter muscle hypertrophy was demonstrated in the patients, and magnetic resonance scan and ultrasound examination were performed for better visualization and muscle measurement. 3D volumetry assessment of musculature showed as additional tool to evaluate the status of the masseter muscles in patients with Masseteric hypertrophy. Therefore, the association of imaging examinations allowed to perform the imaging characterization of masseteric hypertrophy with presence of bone exostosis.

RESUMO A hipertrofia massetérica é uma condição benigna, assintomática e rara, caracterizada pelo desenvolvimento excessivo do músculo masseter, que geralmente resulta em queixas estéticas. São sempre recomendados os exames de imagem para diagnóstico diferencial de patologias na região parotídea-massetérica. Neste trabalho objetiva-se a caracterização da imagem da hipertrofia massetérica através do relato de dois casos clínicos combinando diferentes modalidades de imagem: radiografia panorâmica, ressonância magnética, tomografia computadorizada, ultra-sonografia e volumetria 3D. Dois indivíduos do sexo masculino sem história familiar de hipertrofia massetérica foram encaminhados para um centro de diagnóstico em radiologia dentomaxilofacial devido ao aumento do volume facial bilateral na região massetérica. As imagens da radiografia panorâmica mostraram um aumento do ângulo mandibular bilateral em ambos os casos. Usando tomografia computadorizada, foi demonstrada hipertrofia muscular massetérica bilateral nos pacientes, e a varredura de ressonância magnética e ultra-sonografia foram realizadas para melhor visualização e medição. A avaliação volumétrica em 3D da musculatura mostrou-se como ferramenta adicional para avaliar o estado dos músculos masseteros em pacientes com hipertrofia massetérica. Portanto, a associação de exames de imagem permitiu realizar a caracterização da imagem da hipertrofia massetérica com presença de exostose óssea.

The relationship between masseter muscle thickness measured by ultrasonography and facial profile in young Korean adults

PURPOSE: The purpose of this study was to evaluate the relationship between masseter muscle thickness, facial morphology, and mandibular morphology in Korean adults using ultrasonography. MATERIALS AND METHODS: Ultrasonography was used to measure the masseter muscle thickness bilaterally of 40 adults (20 males, 20 females) and was performed in the relaxed and contracted states. Facial photos and panoramic radiography were used for morphological analyses and evaluated for correlations with masseter muscle thickness. We also evaluated the correlations of age, body weight, stature, and body constitution with masseter muscle thickness. RESULTS: In the relaxing, the masseter was 9.8±1.3 mm in females and 11.3±1.2 mm in males. In the contracted state, it was 12.4±1.4 mm in females and 14.7±1.4 mm in males. Facial photography showed that bizygomatic facial width over facial height was correlated with masseter muscle thickness in both sexes in the relaxed state, and was statistically significantly correlated with masseter muscle thickness in males in the contracted state. In panoramic radiography, correlations were found between anterior angle length and posterior angle length and masseter muscle thickness in females, and between body length and posterior angle length, between anterior angle length and body length, between ramal length and body length, and between body length and condyle length in males. CONCLUSION: Masseter muscle thickness was associated with facial and mandibular morphology in both sexes, and with age in males. Ultrasonography can be used effectively to measure masseter muscle thickness.