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Parkinson's disease is a neurodegenerative disease with manifestations related to oxidative stress and damage to the skeletal striated musculature. This study evaluated the electromyographic fatigue of the masseter and temporal muscles in individuals with Parkinson's disease. The median frequency of the normotensive electromyographic signal was analyzed in 16 individuals, aged between 50 and 70 years, with Parkinson's disease in stages I and III of the Hoehn and Yahr disability scale (n=8) or without the disease (n=8). The data were tabulated and analyzed statistically (t-test, p .05). Compared with the group without Parkinson's disease, the group with the disease showed an increase in the median frequency, with significant differences for the right masseter (p=.05) and the right temporal (p=.03) muscles. The results suggest that there is a link between Parkinson's disease and functional alterations of the masticatory system, especially when electromyographic fatigue is assessed.

Dental absence interferes in the physiological functioning of the masticatory system, promoting occlusal and functional alterations. The purpose of this study was to verify maximal bite force and maximal bite force correlated with electromyographic activity in 14 partially edentulous and 14 dentate individuals. Bite force in right and left molar and incisor regions were registered using a dynamometer with capacity of up to 1000N, adapted for oral conditions and at the same time electromyography was performed using Myosystem-Br1 with electrodes positioned on right and left masseter and temporalis muscles, and one reference electrode on the frontal bone. The highest value out of three recordings was considered the individual's maximal bite force. Statistical analysis of the bite force data was performed by means of t-test and Pearson's bivariate correlation test was used for the analysis between bite and electromyographic activity using SPSS 12.0 software. Dentate individuals showed greater maximal bite force in the three regions. Correlations between electromyographic activity and bite force in the dentate group obtained positive coefficients for every muscle in the right molar region, for the left temporalis in the left molar region, and for every muscle in the incisive region. For the partially edentulous group, only the left temporalis muscle presented a positive correlation in the right molar region, there was positive correlation for the right masseter and right and left temporalis in the left molar region, and, in the incisive region, every muscle presented negative correlation. These data evidence the strong influence of dental loss over the maximal bite force and small correlation between bite force and electromyographic activity.

The aim of this work was to analyze electromyographically the facial muscles: orbicularis oris (upper and lower fascicles), orbicularis oculi (right and left lateral portions) and frontal, in blind and clinically normal (control) individuals, in various clinical conditions. Electromyographic averages of all data collected were normalized by maximal voluntary contraction of the studied muscles and statistical analysis was performed by Student's t test, using "Statistical Package for the Social Sciences" software--SPSS 12.0 (Chicago, IL). It was found that electromyographic alterations occur in the facial musculature that influences facial expressions of individuals. Results for the orbicularis oris muscle demonstrated that myoelectric activity among blind and control subjects was greater for the control group at muscular rest, blowing, and in labial projection. Electromyographic analysis of the orbicularis oculi among blind and control subjects in three clinical conditions studied demonstrated that activity was greater for the control group at muscular rest, blinking, and forced blinking. For the frontal muscles were demonstrated that electromyographic activity was greater for blind individuals. These data suggest the influence of congenital blindness on muscular development, including alterations in electromyographic activity of skin musculature in individuals with visual impairment.

Deaf individuals show a number of difficulties related to the functionality of the stomatognathic system, mainly by reason of the little or no use of facial musculature during speech either due to the use of sign language or to the difficulty that these individuals have in articulating words. The stomatognathic system muscles play important roles in functions such as mastication, deglutition, and phonation. This study aimed to assess, by means of computerized bilateral electromyography (EMG), masseter and temporal muscles of 12 oralized deaf individuals in clinical activities that involve part of this masticatory musculature and compare this system's functionality with that of 12 normal listening individuals, performing the same activities. An 8-channel K6-I EMG Light Channel Surface Electromyography device was used (Myo-Tronics Co.Seattle, WA, USA), in addition to disposable double electrodes covered with silver chloride (Duotrodes; Myo-tronics Co., Seattle, WA) containing a conductor gel (Myogel- Myo-tronics Co., Seatlle, WA). The averaged rectified EMG values were normalized with reference to the EMG amplitude induced by a maximum bite force. The statistical analysis confirmed that there were any significant differences between the groups, clinical activities, and muscles, and also effects of interaction among them. The analysis made use of Variance Analysis (ANOVA). Significant differences (p < 0.01) for both muscles were found among the clinical conditions, with deaf individuals showing greater electromyographic activity for both muscles for the clinical activity protrusion. Deaf individuals showed a lower muscular activity for clinical activities that demanded a greater masseter and temporal muscular activity such as mastication, mouth opening and closing, and dental compression. Greater electromyographic values were found for both deaf individuals and healthy controls during clinical activities of mastication and dental compression. Based on the obtained data, we concluded that deaf individuals showed a lower activity of the masticatory musculature than healthy individuals; the differences were significant at the level of p < 0.01 between the performed clinical activities; and all deaf individuals and healthy controls showed greater electromyographic values for mastication and dental compression.

This study had the aim to analyze electromyographically, the upper and lower fascicles of the orbicularis oris muscle in bilingual, oralist deaf individuals, comparing them with clinically healthy volunteers in mandibular rest position. This was performed in 50 patients of both sexes with an average age of 18.5 years, divided into 4 groups. 1. Ten deaf bilingual, nasal-breathing patients; 2. Ten deaf bilingual, buccal-breathing patients; 3. Ten deaf oralist, nasal-breathing patients; 4. Twenty healthy volunteers, nasal-breathing patients. An electromyograph K6-I EMG Light Channel Surface Electromyography (Myo-tronics Co. Seattle, WA, EUA) of eight channels was used. The electrodes applied were duotrodes, silver-chloride surface, disposable. Statistical analysis was performed using the SPSS software version 10.0 (Chicago, IL). Continuos data with normal distribution were analyzed by univariate analysis of variance (ANOVA). The level of significance was set at alpha= 0.01. Comparing the EMG activity of the orbicularis oris muscle made it possible to verify that, during clinical mandibular rest position, all four groups presented various levels of electromyographic (EMG) activity with statistically significant differences (F = 8.81, p < 0.01). Based this study's data, it was possible to conclude that the electromyography analysis of the orbicularis oris muscle in deaf individuals showed that deaf individuals presented higher levels of EMG activity of the orbicularis oris muscle than normal controls during mandibular rest position.

Aim: This study had the goal of analyzing masseter and temporalis muscles of individuals with Eagle's Syndrome, establishing comparisons with healthy control individuals by means of electromyography, due to the importance of the masticatory musculature upon the various functions of the stomatognathic system and the effects of Eagle's syndrome on this system's functioning., Method: Ten women with Eagle's syndrome and ten healthy controls volunteered to participate in the study. A Myosystem I system, Prosecon Ltda (Uberlândia/MG, Brazil) with 12 channels was used Active differential electrodes were placed on the belly of both masseters and on the anterior temporalis. Firstly, rest position was registered and then the patients were instructed to clench their teeth with maximum strength for four seconds to register the Clenching at Usual Maximum Intercuspation. Next, the clinical conditions of chewing, mandible laterality, and water swallowing were performed., Results: The normalized data of muscle activity during the different clinical conditions and at rest position were compared by Student's t test, considering two groups: controls and syndrome bearers. The masticatory muscles of every syndrome bearers showed hyperactivity during the analyzed clinical conditions; except for chewing, in which the right masseter did not show greater electromyographic activity., Conclusion: It is concluded that individuals with the syndrome showed muscular hyperactivity when compared to healthy individuals, due to the interference of the elongated styloid process, which leads to dysfunctions of the stomatognathic system in the syndrome bearers, with signs and symptoms related to craniofacial pain, dysphagia, otalgy, temporomandibular dysfunctions, and headache.

This study aimed to comparatively analyse the electromyographic activity of the masseter and temporal muscles at rest and during mandible postural clinical conditions (right and left laterality, protrusion and maximum voluntary contraction), right and left maximum molar bite forces and the masticatory efficiency of individuals with schizophrenia or mood disorders - all medicated (medicated groups) compared with control group (healthy volunteers) via electromyography. Individuals were distributed into three groups: Group I (Schizophrenia - 20 individuals), Group II (mood disorders - 20 individuals) and Group III (Control - 40 individuals). Basically, the results were only statistically significant for the clinical mandible conditions and bite force. The most unsatisfactory results were observed in the medicated groups in relation to the control group. The group with mood disorders obtained the most unsatisfactory results compared with the group with schizophrenia. It was suggested by these observations that the association of mood disorders and schizophrenia with medication has negatively affected the stomatognathic system in relation to controls when the electromyography and bite force were used for the analysis. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of age on the electromyographic activity of masticatory muscles. All volunteers were Brazilian, fully dentate (except for Group I – mixed dentition), Caucasian, aged 7–80, and divided into five groups: I (7–12 years), II (13–20 years), III (21–40 years), IV (41–60 years) and V (61–80 years). Except for Group V, which comprised nine women and eight men, all groups were equally divided with respect to gender (20 M/20 F). Surface electromyographic records of masticatory muscles were obtained at rest and during maximal voluntary contraction, right and left laterality, maximal jaw protrusion and maximal clenching in the intercuspal position. Statistically significant differences ( P < 0·05) were found in all clinical conditions among the different age groups. Considerably different patterns of muscle activation were found across ages, with greater electromyographic activity in children and youth, and decreasing from adults to aged people. [ABSTRACT FROM AUTHOR]