Distribución nerviosa interna del músculo temporal humano: consideraciones anatómicas y quirúrgicas / Internal nervous distribution of the human temporal muscle: anatomical and surgical considerations

Resumen Introducción: Conocer en detalle la inervación interna del músculo temporal humano permite realizar múltiples técnicas quirúrgicas y tratamientos de patologías que involucran al territorio craneofacial. Si bien en la literatura se ha descrito la inervación interna del músculo temporal humano basado en micro-disección directa, la técnica de tinción de Sihler es una herramienta ventajosa para el estudio anatómico ya que permite observar ramos nerviosos pequeños sin perder su relación tridimensional con las fibras musculares. Objetivo: Describir la distribución nerviosa al interior del músculo temporal humano en cadáveres al aplicar el método de Sihler y analizar su asociación anátomo quirúrgica. Materiales y Método: Ocho músculos temporales humanos previamente disecados fueron sometidos al método de tinción de Sihler. Cada una de las muestras se observó bajo lupa estereoscópica y transiluminación; finalmente para su descripción se dividió al músculo en tres regiones. Resultados: Se determinó la presencia de tres troncos nerviosos principales: el temporal profundo anterior, el temporal profundo medio y temporal profundo posterior, los que discurren de profundo a superficial. Además, se observaron ramos colaterales de menor calibre del nervio temporal profundo posterior que en forma de arco comunican las tres regiones del músculo. Conclusión: Se describió una distribución nerviosa interna común para los músculos estudiados en las tres dimensiones del espacio, conocimiento útil para innovar en terapias clínico-quirúrgicas del territorio craneofacial.

Introduction: Knowing in detail the inner innervation of the human temporal muscle allows to perform multiple surgical techniques and treatments of pathologies that involve the craniofacial territory. Although the internal innervation of the human temporal muscle based on direct microdissection has been described in the literature, the Sihler staining technique is an advantageous tool for anatomical study since it allows observing small nerve branches without losing its three-dimensional relationship with muscle fibers. Aim: To describe the nervous distribution within the human temporal muscle in cadavers by applying the Sihler method and analyzing its surgical anatomical association. Materials and Method: Eight previously dissected human temporal muscles were subjected to the Sihler staining method. Each one of the samples was observed under stereoscopic magnification and transillumination, finally for its description the muscle was divided into three regions. Results: The presence of three main nervous trunks was determined: the anterior deep temporal, the deep medium temporal and the posterior deep temporal, those that run from deep to superficial. In addition, collateral branches of lesser caliber of the posterior deep temporal nerve that in the form of an arc communicate the three regions of the muscle were observed. Conclusion: A common internal nervous distribution was described for the muscles studied in the three dimensions of space, useful knowledge to innovate in clinical-surgical therapies of the craniofacial territory.

Effect of breast cancer treatment on the stomatognathic system

Abstract Breast cancer is the most common cancer affecting women in the world and provides functional changes in the human body. Evaluate women submitted to unilateral mastectomy, through electromyographic activity (mandibular rest, right and left laterality, protrusion, maximum voluntary contraction with and without Parafilm, habitual and non-habitual mastication) and thickness (rest and maximum voluntary contraction) of the right temporal muscle (RT), left temporal (LT), right masseter (RM) and left masseter (LM), also the molar bite force (right and left) and compare the data with healthy women. Material and Methods: 32 women were divided into two groups: unilateral mastectomy group (MG), average ± standard deviation 56.50±14.50 years (n=16) and without the disease group (CG), average ± standard deviation 56.56±14.15 years (n=16). The normalized electromyographic data, muscle thickness and maximal molar bite force were tabulated and submitted to statistical analysis (SPSS 21.0; student t test, p≤0.05). Significant statistical differences between MG and CG were found in right laterality, for RM (p=0.02); left laterality, for LT (p=0.01); chewing with peanuts, for RM (p=0.04); chewing with raisins, for LM (p=0.04) and right molar bite force (p=0.03). There was no statistically significant difference between MG and CG for muscle thickness. The results of this study suggest that women undergoing unilateral mastectomy may present functional changes, with emphasis on muscular hyperactivity, lower masticatory efficiency and lower maxillary bite force.

Resumo Câncer de mama é a neoplasia mais comum que mais acomete mulheres no mundo e proporciona alterações funcionais no corpo humano. Objetivo: avaliar mulheres submetidas à mastectomia unilateral, por meio da atividade eletromiográfica (repouso mandibular, lateralidade direita e esquerda, protrusão, contração voluntária máxima com e sem parafilme, mastigação habitual e não habitual) e espessura (repouso e contração voluntária máxima) do músculo temporal direito (TD), temporal esquerdo (TE), masseter direito (MD) e masseter esquerdo (ME), além da força de mordida molar (direita e esquerda) e comparar os dados com mulheres saudáveis. 32 mulheres foram distribuídas em dois grupos: grupo mastectomia unilateral (GM), média ± desvio padrão 56,50 ± 14,50 anos (n=16) e grupo sem a doença (GC), média ± desvio padrão 56,56 ± 14,15 anos (n=16). Os dados eletromiográficos normalizados, espessura muscular e força de mordida molar máxima foram tabulados e submetidos à análise estatística (SPSS 21.0; teste t de student, p≤0,05). Foram encontradas diferenças estatísticas significantes entre GM e GC na lateralidade direita, para o MD (p=0,02); lateralidade esquerda, para o TE (p=0,01); mastigação com amendoim, para o MD (p=0,04); mastigação com uva-passa, para o ME (p=0,04) e força de mordida molar direita (p=0,03). Não houve diferença estatística significante entre GM e GC para espessura muscular. Os resultados deste estudo sugerem que mulheres submetidas à mastectomia unilateral podem apresentar alterações funcionais do sistema estomatognático, com destaque para hiperatividade muscular, menor eficiência mastigatória e menor força de mordida molar máxima.

Alterations in the stomatognathic system due to amyotrophic lateral sclerosis

Abstract Objectives: To compare the molar bite force, electromyographic activity, chewing efficiency and thickness of the masseter and temporalis muscles in individuals with amyotrophic lateral sclerosis (ALS) and healthy individuals. Material and Methods: Thirty individuals enrolled in the study were divided into the study group (with ALS, n=15) and control group (healthy individuals, n=15). Data regarding molar bite force (right and left), electromyographic activity (mandibular rest, right and left laterality, protrusion, and maximum voluntary contraction), chewing efficiency (habitual and non-habitual), and masticatory muscle thickness (rest and maximum voluntary contraction) were tabulated and subjected to statistical analysis (Student's t-test, p≤0.05). Results: Comparisons between the groups demonstrated a statistically significant increase in the electromyographic activity of the right masseter (p=0.03) and left masseter (p=0.03) muscles during mandibular rest; left masseter (p=0.00), right temporalis (p=0.00), and left temporalis (p=0.03) muscles during protrusion; and right masseter (p=0.00), left masseter (p=0.00), and left temporalis (p=0.00) muscles during left laterality, in individuals with ALS as compared with healthy individuals. A statistically significant decrease was observed in the habitual chewing efficiency of the right masseter (p=0.00) and right temporalis (p=0.04) muscles in individuals with ALS. No statistically significant difference between the groups was found the masticatory muscle thickness and maximal molar bite force. Conclusions: ALS may lead to modifications in the activities of the stomatognathic system, including muscular hyperactivity and reduction in chewing efficiency; however, no change has been observed in the masticatory muscle thickness and molar bite force.

Myofascial trigger points in patients with temporomandibular joint disc displacement with reduction: a cross-sectional study

Abstract Objective The objective of this retrospective study was to evaluate the impact of myofascial trigger points (MTrPs) in patients with articular disc displacement with reduction (DDWR) and to identify which clinical variables are associated with the concomitant presence of DDWR and MTrPs. Material and Methods 130 patients were selected that sought treatment due to joint pain, with ages ≥18 years, of both genders, with DDWR confirmed by magnetic resonance imaging. The sample was divided into two groups: Group 1, patients with DDWR and MTrPs (N=101); and Group 2, patients with DDWR and no MTrPs (N=29). Information on gender, age, pain duration, pain scores, and maximal interincisal distance (MID) were collected. The logistic regression model was used and the odds ratios (OR) was calculated (p<0.05). Results Group 1 presented statistically significant higher mean pain scores (p=0.007), and smaller MID (p=0.0268) than Group 2. OR were significant for the pain scores (1.429), MID (0.937) and gender (women) (2.810). Conclusions Patients with DDWR and MTrPs had increased pain scores and a MID decrease compared to patients with DDWR and no MTrPs. The variables pain scores, MID, and gender (women) showed a significant association with the concomitant presence of DDWR and MTrPs.

Effects of orofacial myofunctional therapy on masticatory function in individuals submitted to orthognathic surgery: a randomized trial

Abstract Objectives: The esthetic and functional results of orthognathic surgery of severe dentofacial deformities are predictable, however there are differences regarding the effects on stomatognathic system. The aim was to investigate the effects of orofacial myofunctional therapy (OMT) on the masticatory function in individuals with dentofacial deformity submitted to orthognathic surgery (OGS). Material and Methods: Forty-eight individuals (18-40 years) were evaluated, 14 undergoing OMT (treated group-TG), 10 without this treatment (untreated group-UTG) and 24 in a control group with normal occlusion; for clinical aspects the data of an individual was missed (n=46). Chewing was performed using the Expanded protocol of orofacial myofunctional evaluation with scores (OMES-E). Muscle tone and mobility were also analyzed before (P0), three (P1) and six months (P2) after OGS. Surface electromyography of the masseter and temporalis muscles was performed, considering the parameters amplitude and duration of act and cycle, and the number of masticatory cycles. The OMT consisted of ten therapeutic sessions along the postoperative period. The results were compared using parametric and non-parametric tests. Results: TG showed higher scores in P1 and P2 than P0; for the masticatory type the scores in P2 were significantly higher than P0. In addition, the proportion of individuals with adequate tone of lower lip and adequate tongue mobility for TG increased significantly from P1 and P2 in relation to P0. The EMG results showed a decrease in act and cycle duration in P2 in relation to P0 and P1 for the TG; furthermore the values were close to controls. An increase in the number of cycles from P0 to P2 was also observed, indicating faster chewing, which may be attributed to an improvement of balanced occlusion associated with OMT. Conclusion: There were positive effects of OMT on the clinical and electromyography aspects of chewing in individual submitted to orthognathic surgery.

Oral motor and electromyographic characterization of adults with facial fractures: a comparison between different fracture severities

OBJECTIVES: To characterize the oral motor system of adults with facial injuries and to compare the oral motor performance/function between two different groups. METHODS: An observational, descriptive, cross-sectional study was conducted in 38 patients presenting with facial trauma who were assigned to the Division of Orofacial Myology of a Brazilian School Hospital. Patients were divided into two groups: Group 1 (G1) consisted of 19 patients who were submitted to open reduction of at least one facial fracture, and Group 2 (G2) consisted of 19 individuals who were submitted to closed fracture reduction with maxillomandibular fixation. For comparison purposes, a group of 19 healthy volunteers was recruited. All participants underwent a clinical assessment that included an oral motor evaluation, assessment of the mandibular range of motions, and electromyographic assessment of the masticatory muscles. RESULTS: Clinical assessment of the oral motor organs indicated that G1 and G2 presented deficits related to the posture, position, and mobility of the oral motor organs. Patients also presented limited mandibular ranges of movement. Deficits were greater for individuals in G1, especially for maximal incisor opening. Additionally, patients in G1 and G2 presented a similar electromyographic profile of the masticatory muscles (i.e., patients with facial fractures presented lower overall muscle activity and significant asymmetrical activity of the masseter muscle during maximum voluntary teeth clenching). CONCLUSION: Patients in G1 and G2 presented similar functional deficits after fracture treatment. The severity of facial fractures did not influence muscle function/performance 4 months after the correction of fractures.

Short-term transcutaneous electrical nerve stimulation reduces pain and improves the masticatory muscle activity in temporomandibular disorder patients: a randomized controlled trial

Abstract Studies to assess the effects of therapies on pain and masticatory muscle function are scarce. Objective To investigate the short-term effect of transcutaneous electrical nerve stimulation (TENS) by examining pain intensity, pressure pain threshold (PPT) and electromyography (EMG) activity in patients with temporomandibular disorder (TMD). Material and Methods Forty patients with myofascial TMD were enrolled in this randomized placebo-controlled trial and were divided into two groups: active (n=20) and placebo (n=20) TENS. Outcome variables assessed at baseline (T0), immediately after (T2) and 48 hours after treatment (T1) were: pain intensity with the aid of a visual analogue scale (VAS); PPT of masticatory and cervical structures; EMG activity during mandibular rest position (MR), maximal voluntary contraction (MVC) and habitual chewing (HC). Two-way ANOVA for repeated measures was applied to the data and the significance level was set at 5%. Results There was a decrease in the VAS values at T1 and T2 when compared with T0 values in the active TENS group (p<0.050). The PPT between-group differences were significant at T1 assessment of the anterior temporalis and sternocleidomastoid (SCM) and T2 for the masseter and the SCM (p<0.050). A significant EMG activity reduction of the masseter and anterior temporalis was presented in the active TENS during MR at T1 assessment when compared with T0 (p<0.050). The EMG activity of the anterior temporalis was significantly higher in the active TENS during MVC at T1 and T2 when compared with placebo (p<0.050). The EMG activity of the masseter and anterior temporalis muscle was significantly higher in the active TENS during HC at T1 when compared with placebo (p<0.050). Conclusions The short-term therapeutic effects of TENS are superior to those of the placebo, because of reported facial pain, deep pain sensitivity and masticatory muscle EMG activity improvement.

Efeito do tratamento fonoaudiológico após a laserterapia de baixa intensidade em pacientes com DTM: estudo descritivo / Effect of speech-language therapy after low-level laser therapy in patients with TMD: a descriptive study

RESUMO O aumento da dor/desconforto durante atividades como mastigar, falar e deglutir é comumente relatado por pacientes com Disfunção Temporomandibular (DTM) e a terapia fonoaudiológica miofuncional orofacial (TMO) tem sido proposta como parte do tratamento desta condição. Porém é uma modalidade que deve ser instituída quando o quadro de DTM e dor não está exacerbado a fim de não impedir ou dificultar a realização dos exercícios. Objetivo O objetivo deste estudo foi analisar o efeito da TMO no tratamento de pacientes com DTM, segundo o Research Diagnostic Criteria for temporomandibular disorders (RDC/TMD), após analgesia com laserterapia de baixa intensidade (LBI), quanto às condições miofuncionais orofaciais (CMO) e quanto à percepção dos sintomas de DTM. Método Transcorridos 30 dias após a finalização da LBI, cinco pacientes foram avaliados, com idades entre 50 e 61 anos. A aplicação do questionário ProDTMMulti para investigação da autopercepção da sintomatologia de DTM e do exame clínico AMIOFE (Avaliação Miofuncional Orofacial com Escores) para constatação das condições miofuncionais orofaciais foram realizados por fonoaudióloga experiente, antes e após a TMO. Resultados As CMO apresentaram aumento dos escores após TMO, indicando aumento do equilíbrio miofuncional orofacial. De acordo com a percepção das pacientes, após a TMO houve alívio dos sinais e sintomas de DTM. Conclusão A TMO instituída após a analgesia com LBI promoveu equilíbrio das funções orofaciais da amostra estudada e diminuição dos sinais e sintomas de DTM remanescentes, de acordo com a autopercepção dos indivíduos tratados.

ABSTRACT Increased pain and/or discomfort during chewing, speaking, and swallowing have been commonly reported by patients with Temporomandibular Dysfunction (TMD). Speech-language pathology therapy (orofacial myofunctional therapy - OMT) has been proposed as part of the treatment for this condition; however, it is a modality that should be introduced when the TMD context and the pain are not accentuated, so that they do not prevent or hinder the performance of exercises. The aim of this study was to analyze the effect of OMT on the treatment of patients with TMD, according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), after analgesia with low-level laser therapy (LLLT), regarding orofacial myofunctional conditions (OMC) and the perception of TMD symptoms. Five patients aged 50 to 61 years were evaluated 30 days after completion of LLLT. An experienced speech-language pathologist conducted, pre- and post-OMT, the application of the ProDTM Multi-questionnaire - to investigate the self-perception of TMD symptomatology, and the Orofacial Myofunctional Evaluation with Scores (OMES) clinical examination - to confirm the orofacial myofunctional conditions. OMC presented increased OMT scores, indicating an increase in myofunctional orofacial balance. According to the patients' perception, TMD signs and symptoms were relieved after the application of OMT. According to the self-perception of the treated patients, introduction of OMT after LLLT analgesia promoted a balance of the orofacial functions of the sample studied, as well as a decrease in the remaining TMD signs and symptoms.

Effects of cervical mobilization and exercise on pain, movement and function in subjects with temporomandibular disorders: a single group pre-post test

ABSTRACT Objective To investigate the effect of a rehabilitation program based on cervical mobilization and exercise on clinical signs and mandibular function in subjects with temporomandibular disorder (TMD). Material and Methods: Single-group pre-post test, with baseline comparison. Subjects Twelve women (22.08±2.23 years) with myofascial pain and mixed TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders. Outcome measures Subjects were evaluated three times: twice before (baseline phase) and once after intervention. Self-reported pain, jaw function [according to the Mandibular Functional Impairment Questionnaire (MFIQ)], pain-free maximum mouth opening (MMO), and pressure pain thresholds (PPTs) of both masseter and temporalis muscles were obtained. Baseline and post-intervention differences were investigated, and effect size was estimated through Cohen’s d coefficient. Results Jaw function improved 7 points on the scale after the intervention (P=0.019), and self-reported pain was significantly reduced (P=0.009). Pain-free MMO varied from 32.3±8.8 mm to 38±8.8 mm and showed significant improvement (P=0.017) with moderate effect size when compared to the baseline phase. PPT also increased with moderate effect size, and subjects had the baseline values changed from 1.23±0.2 kg/cm2 to 1.4±0.2 kg/cm2 in the left masseter (P=0.03), from 1.31±0.28 kg/cm2 to 1.51±0.2 kg/cm2 in the right masseter (P>0.05), from 1.32±0.2 kg/cm2 to 1.46±0.2 kg/cm2 in the left temporalis (P=0.047), and from 1.4±0.2 kg/cm2 to 1.67±0.3 kg/cm2 in the right temporalis (P=0.06). Conclusions The protocol caused significant changes in pain-free MMO, self-reported pain, and functionality of the stomatognathic system in subjects with myofascial TMD, regardless of joint involvement. Even though these differences are statistically significant, their clinical relevance is still questionable.

Efeito do tempo de contração e repouso na atividade dos músculos masseter e temporal anterior em indivíduos com DTM / Effect of time of contraction and rest on the masseter and anterior temporal muscles activity in subjects with temporomandibular disorder

RESUMO Objetivo O principal objetivo deste estudo foi investigar o efeito do tempo de contração e repouso na atividade dos músculos masseter e temporal. Métodos 49 sujeitos do sexo feminino com idade entre 18 e 30 anos foram divididos em grupos DTM (n: 26) e controle (n: 23). A eletromiografia de superfície foi utilizada para avaliar os músculos temporal anterior e masseter durante protocolos de contração e repouso muscular. Foram analisados os parâmetros eletromiográfico raiz quadrada da média, frequência mediana e o coeficiente da inclinação da reta de regressão linear. Resultados Foi encontrado efeito significativo do tempo no protocolo de contração e de repouso muscular. No protocolo de contração, sujeitos com DTM apresentaram significativa diminuição da frequência mediana no masseter direito e do coeficiente de inclinação do músculo temporal direito comparados ao grupo controle. Conclusão Apesar de os sujeitos com DTM apresentarem maior suscetibilidade à fadiga, comparados aos controles, ambos os grupos devem respeitar o tempo máximo de 5 s de contração voluntária máxima e no mínimo 30 s de repouso entre sucessivas contrações da musculatura mastigatória durante protocolos de avaliação clínica ou de pesquisa.

ABSTRACT Purpose The main objective of this study was to investigate the effect of time of contraction and rest on the masseter and temporal muscles activity. Methods 49 female subjects between 18 and 30 years of age were divided into TMD (n: 26) and control groups (n: 23). Surface electromyograph was used to evaluate the anterior temporal and masseter muscles during contraction and rest protocols. The root means square, median frequency and slope coefficient of the linear regression line parameters were analyzed. Results A significant effect of time in the contraction and rest muscle protocols was found. TMD patients showed a significant decrease in median frequency in the right masseter muscle and the slope coefficient in the right temporal muscle during the contraction protocol to control subjects. Conclusion Despite the TMD patients presented with higher fatigue susceptibility compared to the control group, both groups must meet the maximum time of 5 s of maximum voluntary contraction and at least 30 s rest between successive contractions of masticatory muscles during clinical or research assessment protocols.

Influence of craniomandibular and cervical pain on the activity of masticatory muscles in individuals with Temporomandibular Disorder / Influência da dor craniomandibular e cervical na atividade dos músculos mastigatórios em indivíduos com Disfunção Temporomandibular

Purpose: This study aimed to establish the prevalence of pain in the craniomandibular and cervical spine region in individuals with Temporomandibular Disorders (TMD) and to analyze the effects of these disorders on the bilateral activation of anterior temporalis (AT) and masseter (MA) muscles during the masticatory cycle. Methods: The participants were 55 female volunteers aged 18–30 years. The presence of TMD and craniomandibular and cervical spine pain was evaluated by applying the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) questionnaire and using a combination of tests for the cervical region. The muscle activity of AT and MA during the masticatory cycle was assessed using the symmetry and antero-posterior coefficient indices. Results: The AT activity during the masticatory cycle is more asymmetric in individuals with TMD. The craniomandibular pain, more prevalent in these individuals, influenced these results. Conclusion: Individuals with TMD showed changes in the pattern activity of AT. The craniomandibular nociceptive inputs can influence the increase in asymmetry of the activation of this muscle. .

Objetivo: O objetivo deste estudo foi determinar a prevalência de dor nas regiões craniomandibular e cervical em indivíduos com Disfunção Temporomandibular (DTM) e analisar o efeito dessas desordens na ativação bilateral dos músculos temporal anterior (TA) e masseter (MA) durante o ciclo mastigatório. Métodos: Participaram deste estudo 55 voluntários do sexo feminino com idade de 18 a 30 anos. A presença de DTM e de dor craniomandibular e cervical foi avaliada por meio do questionário Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) e uma combinação de testes para a região cervical. A análise da ativação muscular do TA e MA durante o ciclo mastigatório foi realizada através dos índices de simetria e do coeficiente anteroposterior. Resultados: A atividade dos músculos TA, durante o ciclo mastigatório, é mais assimétrica em indivíduos com DTM. A dor craniomandibular, mais prevalente nesses indivíduos, influencia nesses resultados. Conclusão: Indivíduos com DTM apresentam alteração no padrão mastigatório do músculo TA e estímulos nociceptivos da região craniomandibular podem influenciar no aumento da assimetria de ativação dessa musculatura. .

Tempo de ativação muscular em portadoras de disfunção temporomandibular durante a mastigação / Muscle activation time during chewing in temporomandibular disorder patients

Objetivo Comparar, entre portadoras de disfunção temporomandibular (DTM) e controles, o tempo de ativação do músculo masseter e do músculo temporal anterior, em diferentes faixas de amplitude eletromiográfica de superfície, durante a mastigação. Métodos Foram avaliadas 22 voluntárias, com idades entre 18 e 48 anos, divididas em Grupo DTM (n=14) do tipo “Ia”, de acordo com o Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TDM) e Grupo Controle (n=8), assintomáticas. Foram registrados, por meio de eletromiografia de superfície, a amplitude e o tempo de ativação dos músculos masseter e temporal anterior, durante mastigação bilateral de Parafilm M® por dez segundos. Os sinais eletromiográficos foram categorizados em três faixas percentuais, 0-39%, 40-74% e 75-100%, relativas ao valor médio de amplitude de três contrações máximas de apertamento dentário. As porcentagens dos tempos totais de ativação (duty factor), em cada uma das faixas de amplitude, foram comparadas entre os grupos pelo teste t-Student, para dados não pareados. Resultados Não houve diferenças significativas do duty factor na comparação entre os grupos controle e DTM. Conclusão A variável eletromiográfica testada não se mostrou útil como ferramenta diagnóstica na prática clínica, o que será possível apenas quando em conjunto com a história clínica e exame físico do indivíduo. .

Purpose This study aimed to compare the time of masseter and anterior temporal muscle activations, in different ranges of surface electromyographic amplitude, between controls and individuals with temporomandibular disorders (TMDs) during mastication. Methods Twenty-two female patients, aged 18-48 years, were divided into the TMD group (n=14; TMD type Ia, according to the Research Diagnostic Criteria for Temporomandibular Disorders) and the control group (n=8; non-diagnosed and asymptomatic individuals). Time and surface electromyography (SEMG) amplitudes from the anterior temporal and masseter muscles were registered during bilateral chewing of Parafilm M® for 10 s. SEMG amplitudes were categorized as 0-39%, 40-74%, and 75-100% of the mean of three maximal clenchings. The percentages of total activation times (duty factor) in each range of SEMG amplitudes were compared between groups using an unpaired Student’s t-test. Results: There were no differences in duty factor comparisons between groups. Conclusion: The activation time of the masticatory muscles was not found to be shorter in the TMD patients than in the controls. Finally, the application of the electromyographic variable proposed in this study may not be considered useful to diagnose type Ia TMD in clinical practice. However, its application may be complementary to the history and physical examination of these patients. .

Variação da temperatura superficial dos músculos masseter e temporal anterior durante o apertamento dental voluntário com placas interoclusais maxilares de duas diferentes espessuras / Variation of surface temperature on superficial masseter and anterior temporal muscles during voluntary teeth clenching with maxillary splints of two different thicknesses

A atividade muscular tem sido estudada de maneira indireta pela análise da variação da temperatura superficial cutânea sobre os músculos mastigatórios. Essas mensurações podem representar uma ferramenta valiosa na avaliação clínica da atividade e do progresso das desordens temporomandibulares, bem como no acompanhamento do protocolo terapêutico adotado, justificando sua utilização para verificar alterações patológicas na circulação sanguínea e/ou atividade metabólica nos tecidos abaixo da pele, como os músculos mastigatórios. Em vista disso, o objetivo do presente estudo foi verificar o efeito da espessura da placa interoclusal sobre a variação da temperatura superficial dos músculos temporal anterior e masseter, durante o repouso e o apertamento dental, considerando-se a condição assintomática de 20 indivíduos (10 do gênero masculino e 10 do gênero feminino) selecionados através do questionário Research Diagnostic Criteria (RDC). A temperatura em graus Celsius (ºC) da superfície dos músculos masseter e temporal anterior foi medida com o auxílio de um termômetro digital, com um sistema de leitura por irradiação infravermelha. A temperatura superficial dos músculos temporal anterior e masseter apresentou redução significativa diante do apertamento dental em relação à posição de repouso mandibular. Entretanto, não houve diferenças significantes entre as condições com e sem placa interoclusal, bem como entre as distintas espessuras de placas interoclusais analisadas. Adicionalmente, os músculos mastigatórios apresentaram uma considerável semelhança entre os lados, sem haver também distinções significantes entre o gênero masculino e o feminino.

Muscle activity has been studied indirectly through analyses of temperature variation in skin surface temperature on the masticatory muscles. These procedure may be an important tool for clinical evaluation and assessment of the evolution of temporomandibular disorders, as well as monitoring the adopted protocol. Thus, its utilization for identified pathological alterations on blood circulation and/or on metabolic activity in subcutaneous tissues, such as the masticatory muscles, is justified. The aim of this study was to investigate the effect of occlusal splintsÆ thickness on the variation of surface temperature of the anterior temporal and masseter muscles during rest and clenching. It were analyzed 20 asymptomatic subjects (10 males and 10 females) selected through the Research Diagnostic Criteria (RDC) questionnaire. Temperature expressed in degrees Celsius (ºC) was measured on the surface of both muscles measured with the aid of a digital thermometer with an infrared radiation reading system. The surface temperature of the anterior temporal and masseter muscles presented significant reduction during teeth clenching in relation to the mandibular rest position. However, there were no significant differences between conditions with and without occlusal splint or between the different thicknesses of splints analyzed. Masticatory muscles showed a considerable similar behavior for both sides, and no significant distinctions were observed between male and female patients.

An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth.

Background: To investigate the effect of restoration of lost vertical by centric stabilizing splint on electromyographic (EMG) activity of masseter and anterior temporalis muscles bilaterally in patients with generalized attrition of teeth. Materials and Methods: EMG activity of anterior temporalis and masseter muscle was recorded bilaterally for 10 patients whose vertical was restored with centric stabilizing splint. The recording was done at postural rest position and in maximum voluntary clenching for each subject before the start of treatment, immediately after placement of splint and at subsequent recall visits, with splint and without the splint. Results: The EMG activity at postural rest position (PRP) and maximum voluntary clench (MVC) decreased till 1 month for both the muscles. In the third month, an increase in muscle activity toward normalization was noted at PRP, both with and without splint. At MVC in the third month, the muscle activity without splint decreased significantly as compared to pretreatment values for anterior temporalis and masseter, while with the splint an increase was seen beyond the pretreatment values. Conclusion: A definite response of anterior temporalis and masseter muscle was observed over a period of 3 months. This is suggestive that the reversible increase in vertical prior to irreversible intervention must be carried out for a minimum of 3 months to achieve neuromuscular deprogramming. This allows the muscle to get adapted to the new postural position and attain stability in occlusion following splint therapy.

Non-invasive 3D facial analysis and surface electromyography during functional pre-orthodontic therapy: a preliminary report

OBJECTIVES: Functional orthodontic devices can modify oral function thus permitting more adequate growth processes. The assessment of their effects should include both facial morphology and muscle function. This preliminary study investigated whether a preformed functional orthodontic device could induce variations in facial morphology and function along with correction of oral dysfunction in a group of orthodontic patients in the mixed and early permanent dentitions. MATERIAL AND METHODS: The three-dimensional coordinates of 50 facial landmarks (forehead, eyes, nose, cheeks, mouth, jaw and ears) were collected in 10 orthodontic male patients aged 8-13 years, and in 89 healthy reference boys of the same age. Soft tissue facial angles, distances, and ratios were computed. Surface electromyography of the masseter and temporalis muscles was performed, and standardized symmetry, muscular torque and activity were calculated. Soft-tissue facial modifications were analyzed non-invasively before and after a 6-month treatment with a functional device. Comparisons were made with z-scores and paired Student's t-tests. RESULTS: The 6-month treatment stimulated mandibular growth in the anterior and inferior directions, with significant variations in three-dimensional facial divergence and facial convexity. The modifications were larger in the patients than in reference children. In several occasions, the discrepancies relative to the norm became not significant after treatment. No significant variations in standardized muscular activity were found. CONCLUSIONS: Preliminary results showed that the continuous and correct use of the functional device induced measurable intraoral (dental arches) and extraoral (face) morphological modifications. The device did not modify the functional equilibrium of the masticatory muscles.

Fenómenos autónomos referidos por punto gatillo miofacial en el músculo temporal como una respuesta neuropática / Autonomus referred phenomena by myofacial trigger point in temporalis muscle as a neuropathic response

Los puntos gatillo miofaciales (Pgs) son puntos hiperirritables en un músculo esquelético asociado a un nódulo palpable causado por una banda muscular tensa. Los Pgs miofaciales presentan dentro de sus signos y síntomas alteraciones motoras, sensoriales y autonómicas. En este artículo reportamos un caso en el que se presenta un fenómeno autónomo referido a partir de un punto gatillo miofacial y se plantean las vías neuroanatómicas involucradas en esta respuesta, analizando la hipótesis que las respuestas autónomas referidas asociadas al dolor pueden considerarse eventos neuropáticos del sistema nervioso autónomo.

Myofascial trigger points (MTP) are hyperirritable points in skeletal muscle associated with a palpable lump caused by a strained muscle band. MTP presented within signs and symptoms of motor, sensory and autonomic impairment. In this article we report a case in which an autonomous referred phenomena from a myofascial trigger point and raises the neuroanatomical pathways involved in this response, considering the hypothesis that self-related responses associated with neuropathic pain can be regarded as events of the autonomic nervous system. Clinical and experimental evidence discussed in this article indicates that myofascial trigger point pain is an autonomic phenomena associated, that can be systemic and localized, and must be considered in evaluating patients with these diagnosis.

Electromyographic activity of sternocleidomastoid and masticatory muscles in patients with vestibular lesions

This study evaluated the electromyographic characteristics of masticatory and neck muscles in subjects with vestibular lesions. Surface electromyography of the masseter, temporalis and sternocleidomastoid muscles was performed in 19 patients with Ménière's disease, 12 patients with an acute peripheral vestibular lesion, and 19 control subjects matched for sex and age. During maximum voluntary clenching, patients with peripheral vestibular lesions had the highest co-contraction of the sternocleidomastoid muscle (analysis of covariance, p=0.02), the control subjects had the smallest values, and the patients with Ménière's disease had intermediate values. The control subjects had larger standardized muscle activities than the other patient groups (p=0.001). In conclusion, during maximum voluntary tooth clenching, patients with vestibular alterations have both more active neck muscles, and less active masticatory muscles than normal controls. Results underline the importance of a more inclusive craniocervical assessment of patients with vestibular lesions.

Localization of referred pain in patients with craneocervical muscles trigger points

The pain for miofascial point triggers it can refer to distant territories. Was carried out a retrospective descriptive study of the referred pain presence starting from trigger miofascial points located in masseter, temporalis, trapeze and sternocleidomastoid (SCM) muscles in 50 patients. The masseter was the muscle that presented pain referred with more frequency (n=32; 64 percent), followed by the temporalis (n=18; 36 percent), then the SCM (n=17; 34 percent) and that of smaller frequency was the trapeze (n=2; 4 percent). The presence of two cases of contralateral reference of the masseter is commented and some mechanisms that explain these situations, described in the literature, they are discussed.

El dolor por punto gatillo miofascial puede referirse a territorios distantes. Se realizó un estudio descriptivo retrospectivo de la presencia de dolor referido a partir de puntos gatillo miofascial ubicados en los músculos masétero, temporal, trapecio y esternocleidomastoideo (ECM) en 50 pacientes. El masétero fue el músculo que presentó dolor referido con mayor frecuencia (n=32; 64 por ciento), seguido del temporal (n=18; 36 por ciento), luego el esternocleidomastoideo (n=17; 34 por ciento) y el de menor frecuencia fue el trapecio (n=2; 4 por ciento). La presencia de dos casos de referencia contralateral del masétero es comentada y algunos mecanismos que explican estas situaciones, descritos en la literatura, son discutidos.

Quantitative electromyographic assessment of facial muscles in cross-bite female children / Avaliação eletromiográfica quantitativa de músculos faciais em crianças do sexo feminino com mordida cruzada

The electromyography has been widely used as a diagnostic method for facial muscle conditions. The aim of this study was to determine the RMS (Root Mean Square) value of the electromyographic signal of facial muscles in children with normal occlusion or cross-bite as well as to verify a possible clinical application of this parameter. “Normal group” was composed of female children with normal occlusion and “cross-bite group” was composed of female children with cross-bite. We performed quantitative electromyographic analysis of masseter and temporal muscles at rest and with maximum biting force. Our results showed that the occlusion modifications affect normal masticatory muscle function, and that the quantitative electromyography is an important tool to help diagnosing the malocclusion in female children. Considering the analysis of the results, we verified that the electromyographic rest activity of the masseter or temporal muscles in cross-bite female children is higher in relation to the rest activity of normal occlusion female children. We concluded that the RMS value of the masseteric and temporal electromyographic signal has a diagnostic value to discriminate female children with cross-bite from those with normal occlusion.

A eletromiografia tem sido amplamente utilizada como método diagnóstico de disfunções de músculos da face. O objetivo deste estudo foi determinar a tensão RMS do sinal eletromiográfico de músculos da face de crianças do sexo feminino com oclusão normal ou com mordida cruzada, visando avaliar uma possível aplicação clínica deste parâmetro. O “grupo normal” foi composto por crianças do sexo feminino com oclusão normal e o “grupo mordida cruzada”por crianças do sexo feminino com diagnóstico de mordida cruzada. Foram realizadas análises eletromiográficas quantitativas dos músculos masseter e temporal nas condições de repouso e em máxima contração voluntária isométrica (MCV). Considerando a relação da tensão RMS do sinal eletromiográfico no repouso e em MCV, nossos resultados mostraram que variações de oclusão influenciam a função muscular mastigatória normal e que a eletromiografia quantitativa é uma ferramenta útil para auxiliar o diagnóstico de alterações oclusais em crianças do sexo feminino. Encontrou-se maior atividade eletromiográfica em repouso dos músculos masseter e temporal em crianças do sexo feminino com mordida cruzada em relação às com oclusão normal. Concluímos que a tensão RMS do sinal eletromiográfico massetérico e temporal tem valor diagnóstico para discriminar crianças do sexo feminino com mordida cruzada em relação às com oclusão normal.

Correlation of clinical and MRI findings of tempero-mandibular joint internal derangement.

The most common clinical features of tempero-mandibular joint internal derangement are correlated with the MRI findings of shape of the disc in an attempt to find the etiology of tempero-mandibular joint internal derangement. In this study, the clinical parameters of pain, muscle tenderness, clicking with in the joint (like early, middle and late) are correlated with the MRI findings of disc shapes. (like biconcave, thick, lengthened, folded, adhesion). The study reveals any trauma that leads to muscle tenderness results in internal derangement of tempero-mandibular joint.