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.

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.

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.

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.

Valores de referencia de estudios de electromiografía de los músculos masetero y temporal

los músculos masetero y temporal tienen mucha relevancia en el proceso de masticación; además, suelen verse afectados con enfermedades mioarticulares, neurológicas, entre otras. El objetivo de este estudio es presentar los resultados de electromiografía con electrodo de aguja de los músculos masetero y temporal al momento de la masticación, evaluando los parámetros en amplitud y duración de los potenciales obtenidos. Se tomaron veintiséis individuos con previa valoración de odontología que descartaba alteraciones congénitas, defectos de la masticación y con dinamometría normal en momento de mayor oclusión, a los cuales se les realizó electromiografía de aguja en los músculos masetero y temporal en la máxima oclusión; los resultados fueron analizados bajo el estudio de los valores de amplitud máxima y mínima, así como duración ubicando en percentiles y cuadriles, buscando determinar valores que puedan considerarse normales en esta muestra. Al estudiar el músculo temporal se encontró que la duración normal se encuentra entre 4,75 y 6,487 mseg, mientras que la amplitud se encontraría entre 1572,05 uV y 1038,03 uV; en el caso del músculo masetero, se evidenció que la duración normal se encuentra entre 4,03 y 6,767 mseg, mientras que la amplitud se encontraría entre 2838,43 uV y 1864,635 uV. Este estudio da a conocer valores propios para nuestra población en lo que respecta a duración y amplitud de los potenciales de acción de unidad motora de los músculos temporal y masetero, los cuales concuerdan con los establecidos previamente como normales. En estudios previos realizados en otras partes del mundo, se encontró que la duración es menor que en las extremidades, pero la amplitud es similar, aunque con tendencia a valores inferiores al promedio.

The masseter and temporalis muscles are very relevant in the process of mastication. mastication process; they are also often affected by myoarticular and neurological diseases, among others. This study aims to present the results of electromyography with needle electrodes of the masseter and temporalis muscles at the time of mastication, evaluating the parameters in amplitude and duration of the potentials obtained. Twenty-six individuals were taken with a previous dental evaluation that ruled out congenital alterations, masticatory defects, and with normal dynamometry at the moment of maximum occlusion, to whom needle electromyography was performed in the masseter and temporalis muscles at maximum occlusion; the results were analyzed under the study of the maximum and minimum amplitude values, as well as duration located in percentiles and quadrilles, seeking to determine values that could be considered normal in this sample. When studying the temporal muscle, it was found that the normal duration is between 4.75 and 6.487 msec, while the amplitude would be between 1572.05 uV and 1038.03 uV; in the case of the masseter muscle, it was evidenced that the normal duration is between 4.03 and 6.767 msec, while the amplitude would be between 2838.43 uV and 1864.635 uV. This study reveals values specific to our population in terms of duration and amplitude of the motor unit action potentials of the temporalis and masseter muscles, which agree with those previously established as normal. In previous studies performed in other parts of the world, it was found that the duration is shorter than in the extremities. Still, the amplitude is similar, although with a tendency to lower valuesthan the average.

os músculos masseter e temporal são muito importantes no processo de mastigação. Além disso, eles são frequentemente afetados por doenças mioarticulares, neurológicas e outras. O objetivo deste estudo é apresentar os resultados da eletromiografia com eletrodos de agulha dos músculos masseter e temporal no momento da mastigação, avaliando os parâmetros de amplitude e duração dos potenciais obtidos. Foram tomados 26 indivíduos com avaliação odontológica previa que descartou alterações congênitas, defeitos de mastigação e com dinamometria normal quando da oclusão máxima, nos quais foi realizada a eletromiografia de agulha dos músculos masseter e temporal em oclusão máxima; os resultados foram analisados sob o estudo dos valores máximos e mínimos de amplitude, bem como de duração, colocando-os em percentis e quartis, buscando determinar valores que pudessem ser considerados normais nessa amostra. Ao estudar o músculo temporal, verificou-se que a duração normal está entre 4,75 e 6,487 mseg, enquanto a amplitude estaria entre 1572,05 uV e 1038,03 uV; no caso do músculo masseter, verificou-se que a duração normal está entre 4,03 e 6,767 mseg, enquanto a amplitude estaria entre 2838,43 uV e 1864,635 uV. Este estudo revela valores próprios para nossa população em termos de duração e amplitude dos potenciais de ação da unidade motora dos músculos temporal e masseter, que estão de acordo comos valores previamente estabelecidos como normais. Em estudos anteriores realizados em otros lugares, verificou-se que a duração é mais curta do que nas extremidades, mas a amplitude é semelhante, embora com uma tendência a valores mais baixos do que a média.

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.

Effects of botulinum toxin A injection therapy with ultrasound-guided for benign masseter hypertrophy / 中华医学美学美容杂志

Objective:To evaluate the efficacy of botulinum toxin A injection therapy with ultrasound-guided for benign masseter hypertrophy.Methods:Twenty cases (40 sides) of masseter hypertrophy were injected with botulinum toxin A, among which 10 cases were taken as experimental group and the other 10 cases as control group. The experimental group had preoperative ultrasound examination to measure the thickness of masseter, and use ultrasound-guided precise injection during the operation, and then ultrasound recheck to measure the postoperative masseter thickness; The other 10 cases of control group adopt traditional 3-point injection method.Results:The masseter thickness of the two groups at different period of times after treatment was decreased ( P<0.001), the most obviously decrease happened 4-12 weeks after injection. The mean reduction was 26.8% at 4 weeks and 28.4% at 12 weeks after injection. Masseter muscle thickness recovered by 22% at 24 weeks and by 20% at 36 weeks. The average follow-up was 6.0±2.4 months with no serious complications occurred. In the control group, there was a partial masseter bulge in one case. The satisfactory rate of the patients in the experimental group was higher than that of the control group. Conclusions:Botulinum toxin A injection therapy with ultrasound-guided for benign masseter hypertrophy is an effective treatment, which is more accurate and effective than the traditional injection method.

Hippocampus is involved in 17β-estradiol exacerbating experimental occlusal inter- ference-induced chronic masseter hyperalgesia in ovariectomized rats / 北京大学学报(医学版)

OBJECTIVE@#To investigate the influence of chronic masseter hyperalgesia induced by 17β-estradiol (E2) and experimental occlusal interference (EOI) on underlying mechanism in hippocampus of ovariectomized (OVX) rats.@*METHODS@#In the study, 32 OVX rats were randomly divided into 4 groups (8 rats/group): The control group was OVX group, and 0 μg/d E2 (vehicle) injection was started 7 d after OVX without EOI; in the experimental group (1) OVX + E2 group, 80 μg/d E2 injection was started 7 d after OVX without EOI; in the experimental group (2) OVX + EOI group, vehicle injection was started 7 d after OVX and EOI was applied 17 d after OVX; in the experimental group (3) OVX + E2 + EOI group, 80 μg/d E2 injection was started 7 d after OVX and EOI was applied 17 d after OVX. Bilateral masseter muscle mechanical withdrawal thresholds were measured before OVX, 7 days after OVX (before E2 injection), 17 days after OVX (10 days after E2 injection and before EOI) and 24 days after OVX (7 days after EOI). Immunofluorescence staining was used to reveal phospho-extracellular signal regulated kinase 1/2 (p-ERK1/2)-positive neurons in CA3 of hippocampus. The protein expression of p-ERK1/2 in hippocampus was detected using Western Blot.@*RESULTS@#Compared with the control group [left side: (135.3±8.5) g, right side: (135.4±10.8) g], bilateral masseter muscle mechanical withdrawal thresholds of OVX+E2 group [left side: (113.3±5.6) g, right side: (112.5 ± 5.6) g] and OVX+EOI group [left side: (93.3±5.4) g, right side: 90.8±5.5) g] were decreased (P < 0.01). Bilateral masseter muscle mechanical withdrawal thresholds were significantly lower in OVX+E2+EOI group [left side: (81.2±6.2) g, right side: 79.8±7.7) g] than in the control, OVX+E2 and OVX+EOI groups (P < 0.05). The proportion of p-ERK1/2 positive neurons in the CA3 region of the hippocampus was increased in the control, OVX+E2, OVX+EOI and OVX+E2+EOI groups in turn, and the difference between the groups was statistically significant (P < 0.05). p-ERK1/2 protein expression was increased in the control, OVX+E2 and OVX+EOI groups in turn, but the difference was not statistically significant (P>0.05). p-ERK1/2 expression was significantly higher in OVX+E2+EOI group than in the other three groups (P < 0.05).@*CONCLUSION@#High concentration of E2 could exacerbated EOI-induced chronic masseter hyperalgesia in ovariectomized rats, and its central mechanism may be related to the upregulation of the phosphorylation of ERK1/2 in hippocampus.

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.

Expression of myosin heavy chain isoform mRNA transcripts in the masseter and medial pterygoid muscles / Expresión de transcripciones de ARNm de isoforma de cadena pesada de miosina en los músculos masetero y pterigoideo medial

SUMMARY: Both the masseter and medial pterygoid muscles elevate the mandible, raising the lower jaw by acting simultaneously on the lateral and medial surfaces of the mandibular ramus. Nevertheless, electromyographic studies indicate that these muscles, as well as the superficial and deep heads of the masseter, act in a different way during mastication. We have analyzed by real time quantitative polymerase chain reaction (RT-qPCR) the expression of myosin heavy chain (MHC) isoforms in the masseter and medial pterygoid muscles in humans in order to identify possible differences in the expression patterns that may be related to functional differences identified with electromyography. Our findings indicate that the expression pattern of MHC isoforms in the two muscles is characteristic of fast and powerful phasic muscles. We have also observed a high percentage of expression of the MHC-IIx isoform and the expression of the MHC-M isoform at the mRNA level in both muscles, an isoform that does not translate into protein in the masticatory muscles of humans. The high percentage of expression of the MHC-IIx isoform in humans can be related to a high contractile speed of the masseter and medial pterygoid in humans. On the other hand, the low percentage of expression of the MHC-M isoform at the mRNA level in both muscles can be related to the complex evolutionary process that has reduced the size and force of the masticatory muscles in humans.

RESUMEN: Los músculos masetero y pterigoideo medial elevan la mandíbula actuando de forma simultánea sobre las caras lateral y medial de su rama. Sin embargo, los estudios electromiográficos indican que estos dos músculos actúan de forma diferente durante la masticación, de la misma forma que lo hacen las porciones superficial y profunda del músculo masetero. En el presente estudio hemos analizado mediante PCR en tiempo real la expresión de las isoformas de la cadena pesada de la miosina o myosin heavy chain (MHC) en los músculos masetero y pterigoideo medial en humanos, con la finalidad de identificar diferencias en los patrones de expresión que se puedan relacionar con las diferencias funcionales identificadas con la electromiografía. Nuestros resultados indican que el patrón de expresión de las isoformas de la MHC en los dos músculos es la característica de los músculos rápidos y potentes. También hemos observado un elevado porcentaje de expresión de la isoforma MHC-IIx y la expresión a nivel de ARNm de la isoforma MHC-M en los dos músculos, una isoforma que no se detecta a nivel de proteína en los músculos masticadores humanos. El elevado porcentaje de expresión de la isoforma MHC-IIx que hemos observado se puede relacionar con una elevada velocidad de contracción de los músculos masetero y pterigoideo medial en los humanos. Por otro lado, el bajo porcentaje de expresión de la isoforma MHC-M a nivel de ARNm en ambos músculos se puede relacionar con los procesos evolutivos complejos que han reducido el tamaño y la fuerza de los músculos masticadores en los humanos.

Masseter Muscle Activity in Orthodontically Treated Patients with a History of Temporomandibular Joint Disorder: An Electromyographic Study

ABSTRACT@#The present study aimed to evaluate the surface electromyography (sEMG) activity of the masseter muscles in patients with a history of temporomandibular joint disorder (TMJD) who received orthodontic treatment. In total, 22 participants aged 18–35 years old were included in this study. They were divided into the control group (patients without a history of TMJD [n = 11]) and the test group (those with a history of TMJD [n = 11]). Each participant underwent sEMG of the right and left masseter muscles at 5-s maximum voluntary contraction (MVC). Results showed that the TMJD group had a lower sEMG activity of masseter muscles at MVC than the non-TMJD group. However, the differences were not statistically significant (p > 0.05, t-test). The Spearman’s correlation coefficient test revealed a weak negative correlation between muscle activity on sEMG and history of TMJD (p > 0.05). In conclusion, orthodontically treated patients in TMJD group have reduced masseter muscle activity during MVC, compare to the non-TMJD group.

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.

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.

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

Traumatic myositis chondro-ossificans of masseter muscle associated with TGF-β1, Indian Hegdehog, BMP2, osteopontin and osteocalcin upregulation: Case report

Masseter traumatic myositis chondro-ossificans (TMCO) is a rare pathological condition that causes severe mandibular function restriction. The aim of the present study is to report a TMCO case after direct masseter muscle injury and correlate it to bone and cartilage biomarkers up-regulation. Caucasian male patient, 38 years old, seeks treatment nine days after trauma with severe mouth opening limitation. Physical examination revealed a circumscribed hardened area connected to masseter muscle on the left side. Cone beam tomography and ultrasonography of masseter region were requested. There was incomplete fracture between the posterior board of inferior jaw and coronoid process as well as calcification within masseter muscle. The proposed treatment was excisional biopsy of calcification, coronoid process removal to enhance mouth opening as well as incomplete condyle fracture monitoring. Material removed was sent for histological analysis in order to confirm diagnosis. Immuhistochemistry was conducted and it was found that chondro-ossification biomarkers such as TGF-b1, Indian Hegdehog (IHH), BMP2, osteopontin (OP) and osteocalcin (OC) were up-regulated. One-year follow-up showed that the patient is stable with increased mouth opening and satisfactory jaw movements. Pathologists and maxillofacial surgeons must be aware of differential diagnosis of TMCO. Understanding cellular mechanisms of muscle tissue after trauma is also important once cellular pathway modifications leads to clinical features that differ from previously described in literature.