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.

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)

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.

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.

Avaliação eletromiográfica da musculatura mastigatória e da coluna cervical com uso de placa oclusal: relato de caso / Electromyographic evaluation of masticatory and cervical musculature with occlusal splint: case report

Objetivo: Avaliar a atividade elétrica de músculos mastigatórios e cervicais e sua inter-relação na estabilização da cadeia crânio cervico umeral com uso da placa oclusal, por meio da avaliação eletromiográfica. Relato de caso: Paciente sexo feminino, 39 anos, queixando-se de dores na cabeça, faciais e cervicais, com prejuízo em suas atividades diárias. Relatou apertar os dentes durante o dia e a noite e ser uma pessoa muito ansiosa. Pratica exercício físico de 5 a 6 vezes por semana. Foi submetida ao tratamento com placa oclusal estabilizadora. O exame eletromiográfico foi realizado nos músculos masseter e trapézio, bilateralmente. A coleta de dados foi realizada antes da instalação da placa e passados 90 dias de uso. Considerações finais: Após o tempo de tratamento, foi relatado redução do comportamento de apertamento noturno e diurno dos dentes, redução do nódulo muscular antes visível na região supraescapular, eliminação das dores e melhor rendimento muscular durante a prática de atividade física.(AU)

Objective: To evaluate the electrical activity of masticatory and cervical muscles and their relationship in the stabilization of the craniocervicohumeral chain using a occlusal splint, through electromyographic evaluation. Case report: Female patient, 39 years old, complaining of headaches, facial and cervical pain, with impairment in her daily activities. She reported teeth clenching during the day and night, and being a very anxious person. She practices physical exercise 5 to 6 times a week. She underwent treatment with a stabilizing occlusal splint. The electromyographic examination was performed on the masseter and trapezius muscles, bilaterally. Data was collected before occlusal splint installation and after 90 days of use. Final considerations: After the treatment period, it was reported a reduction in the behavior of nocturnal and daytime teeth clenching, reduction of the muscle nodule previously visible in the suprascapular region, elimination of pain and better muscle performance during the practice of physical activities.(AU)

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.

Botulinum toxin type A and acupuncture for masticatory myofascial pain: a randomized clinical trial

Abstract BoNT-A has been widely used for TMD therapy. However, the potential benefits compared to dry needling techniques are not clear. Objective this study aimed to compare the immediate effects of botulinum toxin type A (BoNT-A) injections and Acupuncture in myofascial temporomandibular disorders (TMD) patients. Methodology 54 women were divided into three groups (n=18). AC patients received four sessions of traditional acupuncture, being one session/week during 20-min. BoNT-A patients were bilaterally injected with 30U and 10U in masseter and anterior temporal muscles, respectively. Moreover, a control group received saline solution (SS) in the same muscles. Self-perceived pain was assessed by visual analog scale, while pressure pain threshold (PPT) was verified by a digital algometer. Electromyographic evaluations (EMG) of anterior temporal and masseter muscles were also measured. All variables were assessed before and 1-month after therapies. The mixed-design two-way repeated measures ANOVA and Tukey's post-hoc tests were used for analysis, considering a=0.05. Results Self-perceived pain decreased in all groups after one month of therapy (P<.001). BoNT-A was not better than AC in pain reduction (P=0.05), but both therapies were more effective in reducing pain than SS (P<0.05). BoNT-A was the only treatment able to improve PPT values (P<0.05); however, a severe decrease of EMG activity was also found in this group, which is considered an adverse effect. Conclusion after one month of follow-up, all therapies reduced the self-perceived pain in myofascial TMD patients, but only BoNT-A enhanced PPT yet decreased EMG.

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.

Relação entre os músculos masseter e esternocleidomastoideo nas situações de flexão e rotação da coluna cervical, em mastigação e máxima intercuspidação habitual, analisados através da atividade eletromiográfica / Relationship between the masseter and sternocleidomastoid muscles in the flexion and rotation functions of the cervical, chewing and maximum habitual intercuspation, analyzed by the electromyographic activity

Na atualidade, com as frequentes inovações tecnológicas agregadas aos telefones celulares favorecendoseu uso excessivo, altos níveis de estresse e o ritmo acelerado da vida, inconscientemente, as pessoas têmadotado novas e diferentes posturas corporais, que direta ou indiretamente interferem na posição da colunavertebral. Um importante músculo postural do pescoço é o esternocleidomastoideo, cuja relevante função éa de estabilizar. Objetivo: analisar a possível relação entre os músculos masseter e esternocleidomastoideo,em diferentes posições da cabeça e da coluna cervical, nas situações de mastigação, repouso e máximaintercuspidação habitual. Metodologia: os dados foram coletados inicialmente com cabeça e coluna eretas,em repouso e em máxima intercuspidação habitual. Em seguida, coletou-se, sempre em mastigação, com acabeça e a coluna eretas, inclinadas para frente, para trás, para direita, para esquerda, giradas para direita epara esquerda. Todos os momentos de coleta de dados ocorreram por 5 segundos em cada posição. Resultados:nota-se um aumento na atividade elétrica do músculo esternocleidomastoideo quando a mastigaçãoacontece com a cabeça e a coluna fora da posição ereta. Em algumas posições da cabeça, esse aumento, emvalores absolutos, não é observado de forma relevante no sexo feminino, sendo notado no masculino. Conclusões:existe uma relação de trabalho entre os músculos masseter e esternocleidomastoideo. Essa relaçãosugere que o segundo músculo trabalha na tentativa de estabilizar a cabeça para otimizar o ato mastigatório,ação essa notadamente encontrada no sexo masculino e de forma menos ativa no sexo feminino.(AU)

Nowadays, with the frequent technological innovations added to cell phones favoring their excessive use, high levels of stress and the fast pace of life, people have unconsciously adopted new and different body postures that directly or indirectly interfere in the position of the spine. An important postural muscle of the neck is the sternocleidomastoid, whose important function is to stabilize it. Objective: to analyze the possible relationship between the masseter and sternocleidomastoid muscles, in different positions of the head and cervical spine, in situations of chewing, resting and maximum habitual intercuspation. Methodology: data were collected initially with head and spine erect, at rest and at maximum habitual intercuspation. Then, it was collected, always chewing, with the head and column erect, tilted forward, backward, right, left, turned to the right and turned to the left. All moments of data collection occurred for 5 seconds in each position. Results: An increase in the electrical activity of the sternocleidomastoid muscle is observed when chewing occurs with the head and spine out of the upright position. In some positions of the head this increase, in absolute values, is not observed in a relevant way in the female sex, being noticed in the male. Conclusions: there is a working relationship between the masseter and sternocleidomastoid muscles. This relationship suggests that the second muscle works in an attempt to stabilize the head to optimize the masticatory act, an action that is notably found in men and less actively in women.(AU)

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

The impact of playing wind musical instruments on the masseter muscles in a West African population

Aim: The morphological dimension of the masseter muscle is largely influenced by physical and habitual activities, which may impact directly on its performance. This study assessed the effects of playing wind musical instruments on the masseter muscle thickness in a male Nigerian adult population.Materials and Methods: Equal numbers of male wind instrument players (WIP) were recruited and compared with nonwind instrument players (non-WIP) of the same age. Information on the sociodemographic characteristics, history, and type of wind instrument played was obtained. The masseter muscle thickness and fractional shortening were determined during relaxation and contraction using a linear probe of 7.5 MHz on ultrasound machine (Biosound Esaote MyLab40 Ultrasound machine; 2012; Italy, Rome). Reliability test demonstrated an excellent intrarater correlation (Cronbach's alpha; 0.98). Data were analyzed using SPSS version 17. Statistical significance was set at P < 0.05.Results: The overall mean thickness of the masseter muscle at relaxation, contraction, and fractional shortening in WIP group was 9.21 ± 1.43 mm, 14.22 ± 1.95 mm, and 35.06% ± 5.07%, respectively, while 8.92 ± 1.12 mm, 13.97 ± 1.44 mm, and 36.08% ± 4.48%, respectively, in non-WIP group. No statistically significant differences were observed between the groups (P > 0.05). Type of instrument played, duration, and frequency of play did not significantly affect the muscle thickness except for the number of years of play. There was also a significant right/left side dichotomy in each group.Conclusions: Playing a wind instrument showed no significant effect on the thickness of the masseter muscle, however there was a significant increase in the muscle thickness with increasing years of play of wind instruments

Análise eletromiográfica do efeito da fisioterapia no músculo masseter em pós-operatório de politrauma de face / Electromyographic analysis of the effect of physical therapy on the masseter muscle in post-operative facial polytrauma

Em situações de acidente, os traumas faciais têm ocupado lugar de destaque, e as fraturas mandibulares compreendem o maior percentual de injúrias tratadas pelos cirurgiões bucomaxilofaciais. Intervenções fisioterapêuticas vêm sendo somadas à reabilitação pós-operatória, otimizando a atividade muscular pós-trauma, colaborando na recuperação das funções mastigatórias, de fonação, deglutição e posturais. Objetivo: o presente estudo objetivou comparar a evolução longitudinal da atividade elétrica do músculo masseter por meio de exame eletromiográfico em um indivíduo politraumatizado submetido à fisioterapia e outro com fratura de mandíbula sem tratamento fisioterapêutico. Sujeitos e método: para tal pesquisa, analisou-se um voluntário politraumatizado submetido a tratamento fisioterapêutico, um voluntário com fratura de mandíbula sem tratamento fisioterapêutico e três voluntários sem fraturas como grupo controle. Foi realizada uma primeira coleta de dados eletromiográficos nos primeiros dias após alta do serviço de cirurgia responsável pelo tratamento das fraturas e uma segunda coleta 60 dias após. No indivíduo submetido ao tratamento fisioterápico, realizou-se ainda uma terceira coleta após 90 dias. Resultados: o voluntário politraumatizado submetido ao tratamento fisioterapêutico, em 90 dias, obteve atividade elétrica do músculo masseter, semelhante ao grupo controle. Já o voluntário com fretura mandibular não submetido ao tratamento fisioterapêutico apresentou resultados semelhantes ao grupo controle após 60 dias de alta hospitalar. Considerações finais: conclui-se que a intervenção fisioterapêutica em pacientes politraumatizados é de grande relevância, devolvendo a condição muscular fisiológica de mastigação, no que tange à atividade elétrica, num prazo de até 90 dias, apresentando, além disso, vantagens na redução da sintomatologia desarmonizadora da função.(AU)

In cases of accident, facial trauma has stood out and mandibular fractures comprise the highest rate of injuries treated by oral and maxillofacial surgeons. Physiotherapeutic interventions have been added to postoperative rehabilitation, optimizing post-trauma muscle activity, aiding the recovery of masticatory, phonation, swallowing, and postural functions. Objective: the present study aimed to compare the longitudinal evolution of the electrical activity of the masseter muscle through electromyographic examination in a polytraumatized individual subjected to physical therapy and another individual with mandibular fracture without physical therapy. Subjects and method: the study analyzed a polytraumatized volunteer subjected to physical therapy treatment, a volunteer with mandibular fracture without physical therapy treatment, and three volunteers without fractures as control group. A first electromyographic data collection was performed in the first days after the discharge from the surgery department responsible for the treatment of fractures, and a second collection occurred 60 days later. In the individual subjected to physiotherapeutic treatment, a third collection was performed 90 days later. Results: the polytraumatized volunteer subjected to the physiotherapeutic treatment obtained, in 90 days, electrical activity of the masseter muscle similar to the control group. The volunteer with mandibular fracture not subjected to physical therapy presented results similar to the control group 60 days after hospital discharge. Final considerations: it is concluded that the physiotherapeutic intervention in polytraumatized patients is of great relevance, returning the physiological muscular condition of chewing, regarding the electrical activity, within a period of up to 90 days, also presenting advantages in the reduction of the function disharmonizing symptomatology.(AU)

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.

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.

Masticatory muscle tendon-aponeurosis hyperplasia accompanied by limited mouth opening

Patients with masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) experience limited mouth opening due to restricted muscle extension. Hyperplastic aponeurosis and tendons lead to the restriction of muscle extension. The criteria for the diagnosis of MMTAH are limited mouth opening that progresses very slowly from adolescence, intraoral palpation reveals a hard cord-like structure along the overhang of the anterior border of the masseter muscle on maximum mouth opening, and a square mandible. Conservative treatment, including pharmacotherapy, occlusal splint and physical therapy are ineffective. The standard therapy is surgical treatment, such as anterior partial aponeurectomy of the masseter muscle and coronoidectomy. The long-term results are very satisfying.

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.

Application of digital mandibular movement record and masticatory muscle electromyography in the evaluation of stomatognathic function in patients with mandibular tumor / 北京大学学报(医学版)

OBJECTIVE@#To study the clinical characteristics of mandibular movement and masticatory muscle function in preoperative and postoperative patients with unilateral mandibular tumors in the region of mandibular body and ramus by combining digital mandibular movement records with electromyography, and to preliminarily explore the relationship and mechanism between movement and masticatory muscle function.@*METHODS@#Six preoperative patients with tumor in unilateral body and ramus of mandible were included, and three postoperative patients with unilateral segmental resection and reconstruction of mandibular bone were included. The mandibular movement recording system and surface electromyography system were used to collect the movement trajectory of the patients' mandibular marginal movement and chewing movement, and the surface electromyography of bilateral masseter and temporalis was recorded concurrently. The surface electromyography of bilateral masseter and temporalis was collected when the patients were at relaxation and at maximal voluntary clenching (MVC). The motion trajectory was observed on the digital virtual model, and the motion amplitude and direction of mandibular marginal movements were analyzed. The characteristics of masticatory electromyogram (EMG) activity in affected and unaffected sides at relaxation, MVC and bilateral mastication were analyzed, and the asymmetry indexes and activity indexes were calculated.@*RESULTS@#The preoperative mean maximum opening of the patients was (35.20±6.87) mm. Three patients had mild mouth opening limitation, and all the patients' mouth opening trajectory was skewed to the affected side. During lateral movements, the mean range of motion of the affected side [(10.34±1.27) mm] and that of the healthy side [(6.94±2.41) mm] were significantly different. The maximum opening of the postoperative patients was (30.65±17.32) mm, and the mandibular marginal movement characteristics were consistent with those of the patients before surgery. During MVC in the preoperative patients, the median EMG activities of the masseter muscle [44.20 (5.70, 197.90) μV] and the temporalis muscle [42.15 (22.90, 155.00) μV] on the affected side were slightly lower than those of the masseter [45.60 (7.50, 235.40) μV] and the temporalis muscle [63.30 (44.10, 126.70) μV] on the healthy side. In the postoperative patients, individualized changes occurred. Some patients suffered from weakened electromyographic activity on the affected side, while some other ones showed hyperelectromyographic activity on the affected side.@*CONCLUSION@#Both benign and malignant tumors as well as their surgery can cause abnormal mandibular movements and change of electromyographic activity of bilateral masseter and temporalis muscles.