Does Parkinson's disease interfere with electromyographic fatigue of masticatory muscles?

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.

Impact of midface and upper face fracture on bite force, mandibular mobility, and electromyographic activity.

This study evaluated the bite force, electromyographic activity, and mandibular mobility in patients undergoing surgery for facial fracture treatment that required a coronal approach. Ten men were divided into two groups: group I, coronal approach with pre-auricular extension (n=4, average age 34.5 years); group II, coronal approach (n=6, average age 24.8 years). The maximum bite force was measured using a dynamometer and mandibular mobility using a calliper. The electromyographic activity of the right masseter (RM), left masseter (LM), right temporal (RT), and left temporal (LT) muscles was evaluated using a Myosystem-Br1 apparatus. Patients were evaluated at 1, 2, 3, and 6 months after surgery. Data were analysed using the repeated measures test (SPSS 21.0; P≤0.05). Statistically significant differences were found for electromyographic activity at rest (group II: LM P=0.00), left laterality (group I: RT P=0.02; group II: RT P=0.04), and maximum voluntary contraction (group I: RM P=0.04 and RT P=0.04; group II: RM P=0.05, LM P=0.00, and LT P=0.01 and for maximum molar bite force in the right (group I, P=0.00; group II, P=0.01) and left (group II, P=0.01) molar regions. The subjects regained electromyographic activity, maximum bite force, and mandibular mobility throughout the period evaluated.

Associations among temporomandibular disorders, chronic neck pain and neck pain disability in computer office workers: a pilot study.

Neck pain is the most common musculoskeletal complaint among computer office workers. There are several reports about the coexistence of neck pain and temporomandibular disorders (TMD). However, there are no studies investigating this association in the context of work involving computers. The purpose of this study was to verify the association between TMD and neck pain in computer office workers. Fifty-two female computer workers who were divided into two groups: (i) those with self-reported chronic neck pain and disability (WNP) (n = 26) and (ii) those without self-reported neck pain (WONP) (n = 26), and a control group (CG) consisting of 26 women who did not work with computers participated in this study. Clinical assessments were performed to establish a diagnosis of TMD, and craniocervical mechanical pain was assessed using manual palpation and pressure pain threshold (PPT). The results of this study showed that the WNP group had a higher percentage of participants with TMD than the WONP group (42·30% vs. 23·07%, χ(2) = 5·70, P = 0·02). PPTs in all cervical sites were significantly lower in the groups WNP and WONP compared to the CG. Regression analysis revealed TMD, neck pain and work-related factors to be good predictors of disability (R(2) = 0·93, P < 0·001). These results highlighted the importance of considering the work conditions of patients with TMD, as neck disability in computer workers is explained by the association among neck pain, TMD and unfavourable workplace conditions. Consequently, this study attempted to emphasise the importance of considering work activity for minimising neck pain-related disability.

Electromyographic analysis of masseter and temporal muscles, bite force, masticatory efficiency in medicated individuals with schizophrenia and mood disorders compared with healthy controls.

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.

Effect of class II and class III dentofacial deformities under orthodontic treatment on maximal isometric bite force.

OBJECTIVE: To determine whether dentofacial deformities influence maximal isometric bite force in affected individuals compared to a control group. DESIGN: A total of 125 volunteer adult patients attended at a hospital participated in the study. Of these, 44 had a confirmed diagnosis of class II deformity (GII: 13 men and 31 women; mean age: 27 years) and 81 had class III deformity (GIII: 35 men and 46 women; mean age 25 years), all of them with indication of orthognathic surgery and under orthodontic treatment. Fifty adult volunteers (CG: 17 men and 33 women; mean age: 22 years) with no alterations of dental occlusion or clinical signs of temporomandibular joint dysfunction participated as controls. Maximal isometric bite force was measured with an electronic gnathodynamometer alternately positioned on each side of the dental arch in the region of the molar teeth and the subjects were instructed to bite it as strongly as possible, with the value being recorded in Newtons. Individuals with good understanding of oral language and with no cognitive or neuromuscular deficits were selected. Data were analysed statistically by the mixed effects model. RESULTS: There was no statistically significant difference (P>.05) in maximal isometric bite force between subjects with class II and class III dentofacial deformities, although the values for both groups were lower than those of control individuals. CONCLUSION: Dentofacial deformity affected maximal isometric bite force regardless of its pattern.

Implant-supported prosthesis following Brånemark protocol on electromyography of masticatory muscles.

This research evaluated the effects of Brånemark protocol on electromyography of the masseter and temporal muscles. The patients were divided into two groups: Group I: patients who wore an implant-supported prosthesis in the mandibular arch following Brånemark protocol, and maxillary removable complete dentures; Group II: dentate individuals (control). Electromyography was carried out at rest, right (RL) and left (LL) laterality, protrusion and maximum voluntary contraction (MVC). Data were compared by t-test. At rest, a higher electromyographic (EMG) activity was observed in Group I, and the values were significant in the right masseter and left temporal muscles. In RL, there were statistically significant differences for right masseter (P < 0·01), left masseter and temporal muscles and for the left temporal muscle in LL (P < 0·05). In protrusion, Group I presented a higher EMG activity, and there was a statistically significant difference for the right masseter muscle (RM) (P < 0·05). In MVC, the EMG values were higher in Group II (control), but significant just for the right temporal muscle (P < 0·05). In conclusion, individuals with mandibular fixed dentures supported according to the Brånemark protocol and maxillary removable complete dentures showed a higher activity of masticatory muscles during the mandibular postural clinical conditions examined; however, in the MVC, Group I presented lower values when compared to dentate group. Despite presenting different EMG values in all of the clinical conditions, both groups showed similar EMG patterns of muscle activation which demonstrates that the proposed treatment can be considered as a good option for oral rehabilitation.

Ageing and surface EMG activity patterns of masticatory muscles.

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.

Correlation between bite force and electromyographic activity in dentate and partially edentulous individuals.

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.

Evidence of muscle role over the cranio-facial skull development in Angle's Class III dental malocclusion under the clinical rest position.

OBJECTIVE: The purpose of this study was to investigate correlations between masseter muscle activity and cephalometric measures in Angle's class III dental malocclusion under the clinical rest position. METHODS: Eight volunteers, both sex, age 7-12, were submitted to an electromyographic analysis of the masseter muscle, subdivided in the upper, medium and lower regions, and to a cephalometric analysis of 15 angle and linear measurements. After normalization, the data was subjected to a statistical, non-parametric Spearman correlation test, by means of the SPSS 12.0 program. RESULTS: Statistically significant correlations were observed between the clinical rest condition before and after the execution of exercises (a serie of mandibular movements), and the cephalometric measurements angle SN GoGn, angle SNA, angle SNB, angle SND, upper incisive. NA angle, upper incisive-NA distance, lower incisive. NB angle, lower incisive-NB distance and angle IMPA, and the different regions of the masseter muscle. CONCLUSIONS: The significant statistical correlation found between the cephalometric analysis and the function of the masseter muscle indicate a strong influence of the musculature under a clinical rest condition over the cranial-facial development in the Angle's class III dental malocclusion. There is a selective activity of the different regions of the masseter muscle under the clinical rest condition in the Angle's class III dental malocclusion. There is a demand for research to complement these findings in other classes of dental malocclusion.

Effect of congenital blindness on EMG activity of the facial muscles.

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.

Histological and histomorphometrical alterations of the periodontal ligament in gerbils submitted to teeth extraction.

This study verified the effect of unilateral teeth extraction on the periodontal ligament in gerbils (Meriones unguiculatus). Ten adult male gerbils weighing about 50 g had induced occlusal alterations by upper left molar extractions while the other ten animals, only submitted to surgical stress, were considered as controls. The periodontal ligament was characterized by qualitative and quantitative analysis, histological description and histomorphometric quantification. Significant alterations were observed on the left side of the experimental group (P < 0.05), the hypofunctional region, when it was compared with the contralateral side and the corresponding region of the control group. Two months after occlusal alterations induced by unilateral teeth extraction, atrophic histological alterations and a decrease in the periodontal space on the ipsilateral side characterized the periodontal ligament. In this study it was possible to conclude that the gerbil can be used in experimental models attempting to correlate the periodontium's biological response to various mechanical stresses, as the periodontal ligament was shown to be highly sensitive to occlusal alterations.

Electromyographic amplitude variability of chewing cycles in deaf individuals.

This study had the goal of determining if the amplitude of the surface electromyograph signals changes in terms of time of analysis and subjects, deaf or normal listeners, when estimated in a 250 ms of length window, visually determined, considering the most stable signal period from the center of the chewing cycle. In order to do this, groups with control subjects, listeners and deaf individuals, who made use of the Brazilian sign language (LIBRAS), were studied. All participants performed continuous 5 s of chewing for the electromyographic recording of the temporalis and masseter muscles. The normalized RMS values of three chewing cycles were compared between and among groups. The results from the Kruskall-Wallis test did not show any statistically significant differences (p > 0.05) between the normalized RMS values obtained in the three individual chewing cycles, for each of the two completed and evaluated cycles, in both groups studied. The Mann-Whitney test showed that the mean normalized RMS values obtained in the first chewing cycle were higher for the control group when compared to the mean amplitude values of the first chewing cycle of the group of deaf volunteers. It can be concluded that, in these experimental conditions, the RMS values obtained from the select windows of 250 ms length duration, in relatively stable periods of the electromyographic signal of chewing cycles did not suffer any changes in terms of EMG register duration, in both studied groups, but does give evidence of the differences among the groups.

Electromyographical analysis of the masseter muscle in dentulous and partially toothless patients with temporomandibular joint disorders.

This study had as objective to analyze with computerized electromyography the masseter muscles bilaterally in twenty individuals with temporomandibular joint dysfunction (DTM), being: the group I consisting of ten individuals with complete dentition and group II constituted by ten individuals with posterior dental absences; comparing nine clinical activities: rest before and after exercises, maximum habitual intercuspation (MIH), right and left laterality, forced centric occlusion, protrusion, bilateral molar bite and chewing. It was utilized the Electromyography K6I-Myotronics, with eight canals and surface silver electrodes. By means of the results analysis, we verified significant differences between the groups (p < 0.01), being group I, presented greater electromyographic activity (32.98 microvolts), than the group II (22.31 microvolts), suggesting that this individuals presented low muscular activity. The interaction between the groups and the clinical activities was significant (p < 0.01), as well as between the groups, clinical activities and muscles (p < 0.05). To clarify which amongst the relative averages the clinical activities were different, calculated the critical value of Tukey, being that rest before and after exercises, MIH, right and left laterality, presented averages with similar distributions, with values below of the values of Tukey, as well as forced centric occlusion, protrusion, bilateral molar bite and chewing presented higher values than Tukey. Based on this research's data, we concluded that the electromyographical analysis of the masseter muscles in Individuals with TMD, dentulous and with dental absence showed that individuals with TMD, dentulous or not, presented elevated muscular activity in rest position and individuals with TMD, dentulous, presented higher electromyographical activity than the individuals with TMD and lacking posterior teeth.

Electromyographic analysis of the masseter and temporal muscles in oralized deaf individuals.

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.

Electromyographic analysis of upper and lower fascicles of the orbicularis oris muscle in deaf individuals, in mandibular rest position, compared to hearers.

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.

Assessment of the maximum voluntary arm muscle contraction in sign language for the deaf.

OBJECTIVE: The purpose of this study was to investigate the levels of upper member muscles' activation of deaf individuals, who use the Brazilian sign language - LIBRAS, comparing these findings to volunteers with no postural deviations and normal hearing METHODS: Forty eight volunteers divided into two groups comprising healthy and deaf subjects (24 volunteers for each group). The signs of rest were obtained with the volunteer maintaining the upper member in an anatomical position, but with the forearm flexed and sustained by the lower member. Maximum voluntary isometric contractions (MVIC) of the biceps, triceps, deltoid, and trapezius muscles were performed in the position of muscular function testing. Statistical analysis was performed using the SPSS-10.0. Continuous data with normal distribution were analyzed by ANOVA with the significance level of p < 0.01. RESULTS: The normalized electromyographic muscle data obtained in muscular rest do not show statistically significant differences among the studies muscles, in both groups. In the comparison of normalized RMS values obtained in MVIC, the mean values for the trapezius muscle of deaf group were statistically lower than control group. CONCLUSIONS: This study's results indicate there are no differences between the levels of muscular activation for arm biceps, arm triceps, and the anterior portion of the deltoid muscle between the mean normalized RMS values of deaf and healthy individuals.

Changes in masticatory muscles activity associated with Eagle's syndrome.

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.

The effect of the Schwartz-Jampel syndrome on masticatory and facial musculatures--an electromyographic analysis.

This study had the goal to perform an electromyography evaluation of the orbicularis oris, orbicularis oculi, masseter, and temporal muscles of two siblings with Schwartz-Jampel syndrome (SJS), in different clinical activities, comparing them to healthy controls (C). The Schwartz-Jampel syndrome is a rare genetic disorder (71 cases reported in worldwide literature), in which myotonia may be observed in the facial muscles, determining a standard facie that shows an appearance of someone who is sad and weeping For the electromyography (EMG), a Myotronics--K61 electromyographer, was used, with superficial and disposable silver chloride electrodes. By means of the analysis of the obtained results, we observed significant statistical differences for the masseter muscle and for orbicularis oculi muscles (p < 0.01) among the studied groups, in which the individuals with SJS presented greater muscular activity than the normal ones, used as healthy controls. The statistical difference between the two groups was not significant for the temporal muscle, as well as for the orbicularis oris muscle, although the EMG averages were much greater in patients who were bringers of the syndrome. This high muscular activity may be related to the facial osseous alterations, evidenced in both patients with SJS, such as the mandibular migrognathia, with an atrophy of the mandibular cortex and a consequent approximation between the inferior dental root apices and the mandible base, as well as the presence of hypoplastic condyles in terms of size and height.