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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]

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The objective was to verify the electrical activity of the Mm. orbicularis oris and mentalis during suction of different liquids in breastfed and non-breastfed children from 2.5-3.5 years old. It was used a signal conditioner (MCS-V2-Lynx Eletrônica Ltda, SP, BR) and Beckman Ag-AgCl bipolar surface electrodes. Breastfed children presented higher activity for mentalis and smaller values for the M. orbicular oris than non-breastfed children, suggesting the existence of different profiles of muscle activation between them. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to evaluate the chewing muscular dynamics and correlate the side of the masticatory movement that is more vertical and/or more horizontal established by the photomeasurement Masticatory Functional Angle (MFA) to the muscular activity behavior, showed in the surface electromyography and in the radiographic images., Material and Method: Seventeen people were selected of both genders, with the average age of 25 years, without signs or apparent symptoms of masticatory muscular disorders. The teleradiographies were done in lateral norm and surface electromyography of the masseter muscles, anterior portion of temporal and supra-hyoids in rest position and maximal bite. The bite force measured with a metallic transducer that was connected to a force sensor (Strain Gauge) to measure the deformation of the material model SF4 (EMG SYSTEM DO BRASIL). A mandibular goniometer of the EMG System of Brazil was used to measure the opening size., Results: The comparison and correlation were established between the groups with MFA>5 degrees and MFA<5 degrees by the test "t" of Student or test of Mann-Whitney conform the distribution was normal or not, respectively. The results showed significant differences between groups, although without sexual dimorphism, to masseter muscle in maximal bite., Conclusion: In conclusion, the anatomic-physiological aspects of temporomandibular disorders are related to the asymmetrical mandible function.

Objective: The aim of this study was to assess the presence of oral myofunctional alterations before and after first premolar extraction in Class II/1 malocclusion patients that could endanger the long-term dental arch stability., Material and Methods: The study was performed by means of morphological, functional and electromyographic analyses in 17 Class II/1 malocclusion patients (group T) and 17 Class I malocclusion patients (group C -control), both groups with 12-30-year age range (mean age: 20.93 +/- 4.94 years)., Results: Data analyzed statistically by Student's t-test showed a significant decrease (p<0.05) in the maxillary and mandibular dental arch perimeters after orthodontic treatment, but lip posture at rest did not present statistically significant differences after treatment (p>0.05). The Kruskal-Wallis test analyzed data from lip posture (orbicularis oris muscle) at rest and during swallowing, as well as the mentalis muscle behavior during the above-mentioned function, not showing statistically significant differences (p>0.05) after treatment (groups T1 and T2). However, group T differed significantly from group C (p<0.05). Lip posture during swallowing showed statistically significant differences (p<0.05) for subjects submitted to orthodontic therapy when compared to data acquired before the treatment. The electromyographic analysis confirmed these data., Conclusions: Found myofunctional alterations observed after the orthodontic treatment in Class II/1 malocclusion seemed to jeopardize the long-term orthodontic stability, making recurrence possible.

Objective: The aim of this study was to assess the existence of myofunctional alterations before and after first premolar extraction in Class II/1 malocclusion patients that could endanger the long-term dental arch stability., Material and Methods: The study was performed by means of morphological, functional and electromyographic analyses in 17 Class II/1 malocclusion patients (group T) and 17 Class I malocclusion patients (group C), both groups with 12-30-year age range (mean age: 20.93 +/- 4.94 years)., Results: Data analyzed statistically by Student's t-test showed a significant decrease in the maxillary and mandibular dental arch perimeters after orthodontic treatment (p<0.05). The Kruskal-Wallis test analyzed data from tongue posture at rest and during swallowing, not showing significant differences after treatment (groups Tb and Ta) (p>0.05). However, group T differed significantly from group C (p<0.05). The electromyographic data showed that the anterior right and left suprahyoid muscles acted synergistically in both groups, while having a lower myoelectric activity in group T during swallowing., Conclusions: Myofunctional alterations observed after the orthodontic treatment in Class II/1 malocclusion seemed to jeopardize the long-term orthodontic stability, making recurrence possible. Further research should be conducted to compare electromyographic data before and after orthodontic treatment in order to corroborate the results of the present investigation.

The aim of this study was to evaluate the prevalence and severity of temporomandibular disorders (TMD) in Brazilian college students. A questionnaire was administered to 2,396 students. Seventy-three percent of women (mean age 21.94 +/- 5 years) and 27% of men (mean age 22.41 +/- 4.8 years) answered the questionnaire. The anamnestic index was used to classify the volunteers according to TMD severity degree. The results showed a higher percentage of men without TMD (43.74%) (p < 0.05, Chi-square test). The women exhibited some degree of severity (73.03%) at a higher frequency than men (56.26%). No significant differences were observed between sexes for a same TMD severity degree (p > 0.05). The results indicated TMD prevalence in Brazilian college students similar to that presented in other studies found in the literature reviewed. Longitudinal studies are recommended to follow the prevalence and health care needs in this population.

The blink reflex latencies and cephalometric indexes were analysed in 30 male volunteers from three different races, 10 white, 10 black, and 10 Oriental. Ages ranged from 15 to 59 years, height from 1,60 to 1,80 m, and weight from 60 to 80 kg. Blink reflexes were obtained after unilateral electric stimulation of the supraorbital nerve for quantitative analysis of 3 responses, early ipsilateral (R1), late ipsilateral (R2i) and late contralateral (R2c), obtained from the orbicularis oculi muscle. Cephalometric indexes were calculated by multiplying the ratio between the longer transverse and the longer saggital head diameters by 100. The R1, R2i and R2c latencies were consistent with other published papers revealing no differences between the different racial groups. The mean of the cephalometric indexes of each group were consistent with respective racial characteristics. This study revealed that there are no differences between R1, R2i and R2c latencies in the 3 different studied races.