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Background: Surface electromyography (EMG) has been used as a reliable tool for the evaluation of electrical muscle activity., Objective: The purpose of this study was to evaluate the EMG indices of the masticatory muscles (masseter, anterior temporalis and suprahyoid) in women with temporomandibular disorder (TMD) and asymptomatic controls in the time domain, by the integrated EMG signal (IEMG) and in the frequency domain, using the median power frequency (MPF)., Methods: An observational, cross-sectional study was conducted involving 30 asymptomatic women as the control (mean age: 25.85 ± 2.57 years) and 74 women with myogenous TMD (mean age: 26.54 ± 2.45 years) diagnosed using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Three EMG readings were taken during maximum voluntary clenching (MVC) of the molars on parafilm for five seconds with a three-minute rest interval between readings. The mixed-model analysis of variance test followed by the Bonferroni correction or the Student-t test was used for the analyses, with the level of significance set to 5% (p < 0.05)., Results: IEMG values were significantly higher in the masseter muscles than the anterior temporalis muscles in the control group (p < 0.01). IEMG values were significantly higher in the masseter muscles of the control group than the group with myogenous TMD (p < 0.05). MPF values of the suprahyoid muscles were significantly higher in the myogenous TMD group than the control group., Conclusions: These significant findings show that women with myogenous TMD have reduction of electrical activity of their masseter muscles and increased firing rate of the motor units of the suprahyoid muscles. These findings may help the treatment of myogenous TMD in women., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Due to the multifactor etiology of temporomandibular disorder (TMD), the precise diagnosis remains a matter of debate and validated diagnostic tools are needed. The aim was to determine the accuracy of surface electromyography (sEMG) activity, assessed in the amplitude domain by the root mean square (RMS), in the diagnosis of TMD. One hundred twenty-three volunteers were evaluated using the Research Diagnostic Criteria for Temporomandibular Disorders and distributed into two groups: women with myogenous TMD (n=80) and women without TMD (n=43). The volunteers were then submitted to sEMG evaluation of the anterior temporalis, masseter and suprahyoid muscles at rest and during maximum voluntary teeth clenching (MVC) on parafilm. The accuracy, sensitivity and specificity of the muscle activity were analyzed. Differences between groups were found in all muscles analyzed at rest as well as in the masseter and suprahyoid muscles during MVC on parafilm. Moderate accuracy (AUC: 0.74-0.84) of the RMS sEMG was found in all muscles regarding the diagnosis of TMD at rest and in the suprahyoid muscles during MVC on parafilm. Moreover, sensitivity ranging from 71.3% to 80% and specificity from 60.5% to 76.6%. In contrast, RMS sEMG did not exhibit acceptable degrees of accuracy in the other masticatory muscles during MVC on parafilm. It was concluded that the RMS sEMG is a complementary tool for clinical diagnosis of the myogenous TMD., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objective: The purpose of this study was to assess the effect of upper thoracic manipulation on vertical mouth opening (VMO) and electromyographic activity of the masticatory muscles in women with temporomandibular disorder (TMD)., Methods: A randomized, controlled, blinded study involving 32 women (mean age of 24.78 ± 5.41 years) diagnosed with TMD was performed. Subjects were randomly allocated to an experimental group (n = 16) or a sham manipulation (placebo) group (n = 16). A single session of manipulation was administered to the T1 vertebral area. Electromyography was used to determine activity of masticatory muscles with the mandible at rest and during isometric contraction. Vertical mouth opening was measured using a ruler. Measurements were made before manipulation, immediately after manipulation, and at the short-term follow-up (2 to 4 days after manipulation)., Results: No significant differences were found in any of the comparisons of mandibular VMO or electromyographic activity of the masticatory muscles at rest or during isometric contraction of mandibular elevator muscles (P > .05). Regarding isometric contraction of the mandibular depressors, an immediate increase in muscle activity was found in the suprahyoid (P = .014) and left masseter (P = .005) muscles., Conclusion: In the present study, no significant differences were found regarding VMO between the experimental and placebo groups or among the different evaluations times in each group. Moreover, Cohen d test revealed no clinical effect of the technique. Therefore, based upon the findings of this study, manipulation administered to the T1 vertebral area appears to have no effect on VMO and electromyographic activity of the masticatory muscles in women with TMD., (Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.)

The aim of the present study was to assess the accuracy of two forms of infrared image analysis (area and extension) of the masseter and anterior temporalis muscles in the diagnosis of myogenous temporomandibular disorder (TMD). A cross-sectional study was carried out involving 104 female volunteers from the university community. Following the application of the Research Diagnostic Criteria for Temporomandibular Disorders, the volunteers were divided into a TMD group (n = 52) and control group (n = 52), and evaluated using infrared thermography. The area and extension of the masseter and anterior temporalis muscles were measured on the images. The receiver operating characteristic (ROC) curve was used to determine diagnostic accuracy (area under the curve), best cutoff point, sensitivity and specificity. A significant difference in skin temperature between groups was only found in the measurement of the area of the left anterior temporalis muscle (p = 0.011). The area under the ROC curve was less than the reference values for all muscles evaluated in the analyses of area and extension. Thus, neither method of infrared thermography tested for the quantification of the masseter and anterior temporalis muscles (analysis of area and extension) is consistent with the RDC/TMD for the diagnosis of myogenous TMD in women., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objective: The purpose of this study was to evaluate the accuracy of infrared thermography of the central point of the masseter and anterior temporalis muscles for the diagnosis of myogenous temporomandibular disorder (TMD)., Methods: This is an observational study of university women with and without TMD. Through the use of the Research Diagnostic Criteria for Temporomandibular Disorders, 104 women were divided into a TMD group (n = 52) and control group (n = 52). All volunteers had their masseter and anterior temporalis muscles evaluated by infrared thermography. The receiver operating characteristic (ROC) curve was used to determine the accuracy of diagnosis (area under the ROC curve), the best cut-off point, sensitivity, and specificity., Results: No significant differences were observed (P > .05) in the skin surface temperature of the masticatory muscles, when the groups were compared. With regard to the ROC curve, the area under the curve was lower than the recommended for all the muscles tested, ranging from 0.433 to 0.502., Conclusion: The findings of this study suggest that infrared thermography of the masticatory muscles is not an accurate instrument for the myogenous TMD diagnosis., (Copyright © 2013 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.)

Background: Infrared thermography is an aid tool that can be used to evaluate several pathologies given its efficiency in analyzing the distribution of skin surface temperature., Objectives: To propose two forms of infrared image analysis of the masticatory and upper trapezius muscles, and to determine the intra and inter-rater reliability of both forms of analysis., Method: Infrared images of masticatory and upper trapezius muscles of 64 female volunteers with and without temporomandibular disorder (TMD) were collected. Two raters performed the infrared image analysis, which occurred in two ways: temperature measurement of the muscle length and in central portion of the muscle. The Intraclass Correlation Coefficient (ICC) was used to determine the intra and inter-rater reliability., Results: The ICC showed excellent intra and inter-rater values for both measurements: temperature measurement of the muscle length (TMD group, intra-rater, ICC ranged from 0.996 to 0.999, inter-rater, ICC ranged from 0.992 to 0.999; control group, intra-rater, ICC ranged from 0.993 to 0.998, inter-rater, ICC ranged from 0.990 to 0.998), and temperature measurement of the central portion of the muscle (TMD group, intra-rater, ICC ranged from 0.981 to 0.998, inter-rater, ICC ranged from 0.971 to 0.998; control group, intra-rater, ICC ranged from 0.887 to 0.996, inter-rater, ICC ranged from 0.852 to 0.996)., Conclusion: The results indicated that temperature measurements of the masticatory and upper trapezius muscles carried out by the analysis of the muscle length and central portion yielded excellent intra and inter-rater reliability.

Background and Objective: Pain is a common clinical manifestation in individuals with temporomandibular disorder (TMD). The literature report changes in microcirculation in this condition. The aim of the present study was to correlate skin surface temperature at the central point of the masticatory muscles with pain intensity in women with myogenous TMD., Materials and Methods: The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and the visual analogue scale (VAS) were used to divide 40 female university students into four groups: control group (n=10), mild pain group (n=10), moderate pain group (n=10) and severe pain group (n=10). Infrared thermography was used to assess the masticatory muscles., Results: No significant correlations were found between pain intensity and skin surface temperature over the left masseter (p=0.368), right masseter (p=0.618), left anterior temporalis (p=0.293) and right anterior temporalis (p=0.922) muscles. No correlations were found between pain intensity and asymmetry of the masseter (p=0.375) and anterior temporalis (p=0.090) muscles. Moreover, no significant difference in skin surface temperature (p> 0.05) was found among the different groups., Conclusion: Pain intensity in women with myogenous TMD was not associated with skin surface temperature at the central point of the masseter and anterior temporalis muscles.

To verify the characteristics of the electromyographic signal of masticatory muscles in individuals with TMD and asymptomatic individuals. A systematic review was carried out, selecting cross-sectional studies with at least one electromyographic parameter (FM; iEMG; RMS) of the masticatory muscles (anterior temporal, bilateral masseter, and suprahyoid muscles) of individuals with TMD compared to asymptomatic individuals. This review identified 1656 titles, of which 30 articles were included in the final analysis. It was observed that the data referring to the pattern of activation of masticatory muscles in the rest, isometry, and isotonic conditions of individuals with TMD are heterogeneous. This fact may be related to variability in the methods and analyses applied in the studies. Data referring to the pattern of activation of masticatory muscles in the rest and isometry conditions and in the mastication cycle of individuals with TMD and asymptomatic individuals are diverse. [ABSTRACT FROM AUTHOR]

Aim: The study aimed to evaluate the accuracy of the maximum bilateral molar bite force and the Root Mean Square (RMS) Electromyography (EMG) index of the masticatory muscles in the maximum bilateral molar bite (MMBMax) of women with myogenic Temporomandibular Disorder (TMD) and asymptomatic. Methods: This is a cross-sectional study, composed of 86 women allocated to the TMD Group (n=43) and Control Group (n=43) diagnosis through the Diagnostic Criteria for Temporomandibular Disorders. The maximum bilateral molar bite force was evaluated using a bite dynamometer and the RMS EMG index of the masticatory muscles (anterior temporalis, masseter) during 5 seconds of the MMBMax task. Student t-test was used for data comparison between accuracy of the bite force and RMS EMG of masticatory muscles during the MMBMax. Results: The maximum bilateral molar bite force showed high accuracy (AUC=0.99) for the diagnosis of women with myogenic TMD and asymptomatic women, and the RMS EMG index evaluated during the MMBMax showed a moderate level of accuracy for all masticatory muscles (AUC=0.70 to 0.75). Conclusion: The bilateral bite dynamometer with a surface EMG during bilateral bite can be used to diagnose TMD in young women. [ABSTRACT FROM AUTHOR]

There is no consensus on the most appropriate method for normalizing electromyography (EMG) signals from masticatory muscles during isotonic activity. Aim: To analyze the best method for data processing of the EMG signal of the masticatory muscles during isotonic activity (non-habitual chewing), comparing raw data and different types of normalization. Methods: This is a cross-sectional study. Women aged between 18 and 45 years were selected. Anthropometric data were collected (age, height, body mass index -- BMI, masticatory preference) as well as EMG signal (root mean square -- RMS) data for the anterior temporal and masseter bilaterally, and for the suprahyoid muscles, during isotonic (non-habitual chewing) and isometric tasks. EMG data were processed offline using Matlab® Software. The normalization of the EMG signal was carried out using the 2nd masticatory cycle, chosen at random, of the 20 cycles collected, the maximum RMS value, and the maximum voluntary contraction (MVC). To analyze the best method of data processing for the isotonic data, the coefficient of variation (CV) was calculated. Descriptive data analysis was adopted, using the mean and standard deviation. ANOVA with repeated measures was used to detect significant differences between the methods of normalization. Statistical significance was set at 5% (α<0.05). Results: The final sample of this research was composed of 86 women. The volunteers presented an average age of 27.83±7.71 years and a mean BMI of 22.85±1.91 Kg/m². Regarding masticatory preference, 73.25% reported the right side, and 26.75% the left side. Considering the comparison between the methods, the %CV measure of the 2nd cycle showed the lowest variation coefficient during biting for all the muscles from the raw data, RMS Max, and MVC (p=0.001, p=0.003, and p=0.001 respectively). Conclusion: In conclusion, for non-habitual chewing activity, the results of this study recommend data processing using normalization with the second cycle during chewing. [ABSTRACT FROM AUTHOR]

Background: Excessive use of smartphones may be associated with behavioral and physical health changes and might cause musculoskeletal alterations in the head and neck region. Objective: To evaluate the prevalence of smartphone addiction in college students and its correlation with symptoms of head and neck pain and masticatory and trapezius muscle activity while resting, before and after smartphone use. Methods: Twenty university students participated in the study. They answered the Smartphone Addiction Scale and the Fonseca Anamnestic Index. Next, the participants were seated and prepared for electromyography through the placement of surface electrodes on the masseter, temporal, and trapezius muscles. Rest condition data were collected for 10 seconds before and after 30 minutes of smartphone use. Results: The results showed that 35% of the evaluated individuals were classified as smartphone addicted and 35% reported no head or neck pain in the previous 30 days. There was no association between smartphone use and head and neck pain. In the electromyography, there was an increase in RMS values after smartphone use in the right and left masseter muscles and the left trapezius. Conclusion: College students presented a high prevalence of smartphone addiction and head and neck pain, but these were not statistically associated. There was a change in muscle activity only in the right trapezius muscles before and after 30 minutes of smartphone use. These findings are contrary to the current belief that the use of smartphones correlates with pain in the neck region and changes in the electrical muscle activity, leading to fatigue in the cervical muscles. [ABSTRACT FROM AUTHOR]

Aim: To verify whether patients with temporomandibular disorders (TMD) present masticatory muscle hyperactivity with the mandible in the rest position. Method: Forty-six women were selected (18-33 years-old, mean age = 22.7 ± 3.52 years), 31 with TMD (experimental group) and 15 without TMD (control group). Electromyography (EMG) was performed in two situations: 1) with the mandible in the rest position and 2) in maximal dental clenching. RMS (root mean square) was used for EMG signal analysis. Data were analyzed statistically by the Mann Whitney U-test. Result: The experimental groups presented increased EMG activity of the muscles evaluated with the mandible in the rest position compared to the control. In maximal dental clenching, no differences were observed between the groups. Analyzing the percentage of EMG activity at rest, the control group presented EMG activity around 1 to 6% of maximal dental clenching and the experimental group, around 1 to 12% of the same activity. Conclusion: The experimental group presented an increase in EMG activity at rest in the studied muscles, mainly in the anterior portion of the temporal muscle, bilaterally. However, this increase should not be called muscular hyperactivity, but should rather be considered as an important sign of TMD. [ABSTRACT FROM AUTHOR]