Influence of sleep bruxism severity on masticatory efficiency: electromyographic analysis.

The objective of the present study was to ascertain masticatory efficiency by evaluating electromyographic activity in the masseter and temporalis muscles in subjects with sleep bruxism of varying severity, as determined by BiteStrip. Thirty-four subjects with sleep bruxism were divided into two groups: a mild sleep bruxism group with a mean (± standard deviation) age of 31.3 ± 6.2 years (n = 15) and a severe sleep bruxism group with a mean age of 29.8 ± 7.1 years (n = 19). Full-night polysomnography (PSG) was performed in eligible subjects. The linear envelope integral was used to determine masticatory efficiency on the basis of the electromyographic signal of the masseter and temporalis muscles during habitual and non-habitual chewing. There was significantly higher (p .05) electromyographic activity in the severe bruxism group than in the mild bruxism group during both peanut chewing in the right (p = .03) and left (p = .03) temporalis muscles and raisin chewing in the right (p = .01) and left (p = .05) temporalis muscles. Furthermore, Parafilm M chewing showed similar results in the right (p = .008) and left (p = .02) temporalis muscles. These results suggested that subjects with severe sleep bruxism had lower masticatory efficiency.

Analysis of the sleep period and the amount of habitual snoring in individuals with sleep bruxism.

BACKGROUND: The literature does not report any association between habitual snoring and sleep bruxism, but these situations can be a reason for frequent complaints of individuals, impairing the quality of life. This study was performed to investigate the sleep period and amount of habitual snoring in individuals with sleep bruxism observing expiratory, inspiratory, and mixed snoring. MATERIAL AND METHODS: A total of 90 individuals were screened and divided into the following groups: with sleep bruxism (n=45) and those without sleep bruxism (n=45). Single night sleep polysomnography was performed to diagnose sleep bruxism, quantify habitual snoring and sleep period. The results were tabulated and submitted to a Multivariate analysis of variance (MANOVA) to compare the means of the two independent groups, considering the affected diagnosis of sleep bruxism, snoring (independent variables) and age as covariate. For the post hoc, was used correcting for multiple comparisons (Bonferroni test, P<.05). RESULTS: There was statistically significant difference among the groups ( p=.001) in the sleep period, in that individuals with sleep bruxism slept for a longer duration (with sleep bruxism group: 460 minutes and without sleep bruxism group: 401 minutes). There were no statistically significant differences among the groups for the number of inspiratory, expiratory and mixed snores, but was observed greater amount of snoring in the with sleep bruxism group. CONCLUSIONS: The main finding of this study is that individuals with sleep bruxism slept longer than the control group. It may also be suggested that individuals with sleep bruxism tended to increase the amount of habitual snoring during sleep.

Impact of Parkinson's disease on the efficiency of masticatory cycles: Electromyographic analysis.

BACKGROUND: This study evaluated the efficiency of masticatory cycles by means of the linear envelope of the electromyographic signal of the masseter and temporalis muscles in individuals with Parkinson's disease. MATERIAL AND METHODS: Twenty-four individuals were assigned into two groups: with Parkinson's disease, average ± SD 66.1 ± 3.3 years (n = 12) and without the disease, average ± SD: 65.8 ± 3.0 years (n = 12). The MyoSystem-I P84 electromyograph was used to analyze the activity of masticatory cycles through the linear envelope integral in habitual mastication of peanuts and raisins and non-habitual mastication of Parafilm M®. RESULTS: There was statistically significant difference (P ≤ 0.05) between individuals with Parkinson's disease and without the disease in non-habitual mastication of Parafilm M®, in the right temporal muscle (P = 0.01); habitual mastication of peanuts, in the right temporal muscle (P = 0.02), left temporal muscle (P = 0.03), and right masseter muscle (P = 0.01); and habitual mastication of raisins in the right temporal muscle (P = 0.001), left temporal muscle (P= 0.001), right masseter muscle (P= 0.001) and left masseter muscle (P= 0.03). CONCLUSIONS: These results suggest that Parkinson's disease interferes in the electromyographic activity of the masticatory cycles by reducing muscular efficiency.

Spinocerebellar ataxia: Functional analysis of the stomatognathic system.

BACKGROUND: Neurodegenerative diseases that affect the cerebellum, especially in elderly individuals, cause impairment of motor coordination and quality of life. The presente study evaluated the electromyographic activity and thickness of the right and left masseter and temporal muscles, and the maximum molar bite force of individuals with spinocerebellar ataxia. MATERIAL AND METHODS: Twenty-eight individuals were divided into two groups: those with (n=14) and without (n=14) spinocerebellar ataxia. Data on the masticatory muscles obtained from the electromyographic activity (resting, right and left laterality and protrusion), muscle thickness (maximal voluntary contraction and tensile strength) and maximum bite force (right and left) were tabulated and descriptive analysis using Student's t-test (P ≤ 0.05). RESULTS: In the comparison between groups, greater electromyographic activity was demonstrated for individuals with spinocerebellar ataxia, with a statistically significant difference in protrusion and laterality for the temporal muscles (P = 0.05). There was no statistically significant difference between the groups for masticatory muscles thickness in the conditions evaluated. For maximum molar bite force, the group with spinocerebellar ataxia showed lower bite force (P ≤ 0.05). CONCLUSIONS: The data obtained suggest that spinocerebellar ataxia promotes functional reduction in the stomatognathic system, mainly affecting the electromyographic activity and bite force, hindering chewing, with a resultant alteration of nutritional intake and a decrease of quality of life.

Spinocerebellar ataxia: Functional analysis of the stomatognathic system

Background: Neurodegenerative diseases that affect the cerebellum, especially in elderly individuals, cause impairment of motor coordination and quality of life. The presente study evaluated the electromyographic activity and thickness of the right and left masseter and temporal muscles, and the maximum molar bite force of individuals with spinocerebellar ataxia. Material and Methods: Twenty-eight individuals were divided into two groups: those with (n=14) and without (n=14) spinocerebellar ataxia. Data on the masticatory muscles obtained from the electromyographic activity (resting, right and left laterality and protrusion), muscle thickness (maximal voluntary contraction and tensile strength) and maximum bite force (right and left) were tabulated and descriptive analysis using Student’s t-test (P ≤ 0.05). Results: In the comparison between groups, greater electromyographic activity was demonstrated for individuals with spinocerebellar ataxia, with a statistically significant difference in protrusion and laterality for the temporal muscles (P = 0.05). T here was no statistically significant d ifference b etween t he g roups for m asticatory muscles thickness in the conditions evaluated. For maximum molar bite force, the group with spinocerebellar ataxia showed lower bite force (P ≤ 0.05). Conclusions: The data obtained suggest that spinocerebellar ataxia promotes functional reduction in the stomatognathic system, mainly affecting the electromyographic activity and bite force, hindering chewing, with a resultant alteration of nutritional intake and a decrease of quality of life

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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.

Evaluation of the electromyographic activity of masseter and temporalis muscles of women with rheumatoid arthritis.

AIM: This study aimed to evaluate the electromyographic activity of the masseter and temporalis muscles of women with rheumatoid arthritis. METHODS: The sample comprised 28 women divided into two groups: 14 with rheumatoid arthritis [mean age: 52.2 ± standard deviation (SD): 3 years] and 14 without rheumatoid arthritis (mean age: 49.4 ± SD: 2.4 years). The women were paired by age and body mass index. The electromyographic activity of the masseter and temporalis muscles was analyzed in mandibular tasks: rest, right and left laterality, protrusion, maximal voluntary contraction with and without Parafilm M®, habitual and non-habitual chewing. The MANOVA (multivariate analysis of variance) was used to compare the means of the two independent groups, considering as independent variable side and diagnosis of rheumatoid arthritis, and age as the covariate. The Bonferroni correction was used for the post hoc comparisons (p <0.05). RESULTS: Rheumatoid arthritis group presented an increase in the normalized electromyographic activity of the masticatory muscles and lower mean values for the habitual and non-habitual chewing. CONCLUSIONS: Women with rheumatoid arthritis showed functional alterations in the stomatognathic system, demonstrated through muscular hyperactivity and reduction of masticatory efficiency. HIPPOKRATIA 2018, 22(1): 3-9.

Impact of temporomandibular disorders on the stomatognathic system in children.

BACKGROUND: To evaluate the EMG activity and thickness of right masseter (RM), left masseter (LM), right temporal (RT) and left temporal (LT) muscles and bite force in children with temporomandibular disorders (TMD). MATERIAL AND METHODS: Forty five children (mean age 8.8 years; 22 boys and 23 girls) were examined on the basis of the RDC/TMD and the Faces Pain Scale-Revised (FPS-R) was used to determine the level of severity of the signs and symptoms of TMD, resulting in four groups: GI - without TMD (n=10); GII - with mild TMD (n=18), GIII: with moderate TMD (n=12) and GIV: with severe TMD (n=5). The data of electromyographic activity, maximum bite force and muscle thickness were tabulated and submitted to statistical analysis (ANOVA, P≤0.05). RESULTS: Children with TMD signs and symptoms had lower EMG activity than children of the control group. There was significant difference among the groups for the LT at rest (P=0.01), right (P=0.03) and left (P=0.05) laterality, and for the LM (P=0.01) and LT (P=0.03) muscles in maximum voluntary contraction. There were no statistically significant differences among the groups regarding muscle thickness. The bite force was lower in the TMD groups than children of the control group, with significant statistical difference for the right region (P=0.03). CONCLUSIONS: The severity of TMD signs and symptoms affected the EMG activity and the molar bite force in children. However, structural changes in the thickness of masticatory muscles are not perceptible in children with TMD signs and symptoms.

Masticatory muscle activity evaluation by electromyography in subjects with zygomatic implants.

BACKGROUND: Zygomatic implants are an alternative treatment in the rehabilitation of atrophic maxilla to promote stability in the stomatognathic system. The aim of this study was to compare the electromyographic (EMG) activity of masseter and temporalis muscles in controls and in individuals with complete implant-supported dentures anchored in the zygomatic bone. MATERIALS AND METHODS: Fifty-four volunteers of both genders (mean age 52.5 years) were selected and distributed into two groups: Individuals with zygomatic implant (ZIG; n=27) and fully dentate patients (CG; n=27). MyoSystem-BR1 was used to assess masseter and temporalis muscles EMG activity in different mandibular movements: protrusion, clenching, maximal voluntary contraction (MVC) with Parafilm M®, right and left laterality and chewing (peanuts and raisins). Data was processed, normalized (MVC) and analyzed using the SPSS 21.0. Student t-test (P ≤ 0.05) was used for group comparison. RESULTS: The results were statistically significant (P ≤ 0.05) for protrusion, clenching, right and left laterality and raisin chewing. For the mandibular posture conditions, the ZIG obtained higher EMG activity patterns when compared to CG. For the masticatory performance during chewing of peanuts and raisins, the ZIG showed higher EMG mean values when compared to CG. CONCLUSIONS: The zygomatic implant promoted an active response of the muscle fibers (hyperactivity) during both mandibular posture and chewing conditions, probably due to the absence of periodontal receptors, which play a significant role for preparing a bolus for swallowing.

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.

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.

Anatomical variations of the mandibular nerve and its branches correlated to clinical situations.

AIM: The mandibular division of the trigeminal nerve is the largest of the three major divisions of the trigeminal nerve (fifth cranial nerve). In this way, many health professionals belonged to different fields are commonly evaluating patients suffering with orofacial pain and stomatognatic dysfunction associated to this structure. But, in the most cases, it is difficult to establish a correct diagnosis due to the anatomical complexity of the head and neck surfaces, especially when the focus is the trigeminal nerve. Thus, the objective of this research was to present the anatomical variations of the mandibular nerve and its branches correlated to more common clinical situations. METHODS: For this purpose, 20 human heads were anatomically dissected, so to study their structures, an external, medial and endocranial view. RESULTS: No significant variations related to ophthalmic and maxillary nerves were observed. Anatomical variations were observed in 20% of the total human heads dissected, all related to mandibular nerve and its branches: masseter, temporal, auriculotemporal and lingual. Variations in three to seven, on the number of the following nerves ramus, masseter and temporal were described. CONCLUSIONS: According to the present data using the described methodology, it was possible to conclude that anatomical variations are present in many subjects and they can explain many clinical situations that involve the stomatognathic structures.

Masticatory process in individuals with maxillary and mandibular osteoporosis: electromyographic analysis.

UNLABELLED: The masseter and temporal muscles of patients with maxillary and mandibular osteoporosis were submitted to electromyographic analysis and compared with a control group. In conclusion, individuals with osteoporosis did not show significantly lower masticatory cycle performance and efficiency compared to the control group during the proposal mastications. INTRODUCTION: This study aimed to examine electromyographically the masseter and temporal muscles of patients with maxillary and mandibular osteoporosis and compare these patients with control patients. METHODS: Sixty individuals of both genders with an average age of 53.0 +/- 5 years took part in the study, distributed in two groups with 30 individuals each: (1) individuals with osteoporosis; (2) control patients during the habitual and non-habitual mastication. The electromyographic apparel used was a Myosystem-BR1-DataHomins Technology Ltda., with five channels of acquisition and electrodes active differentials. Statistical analysis of the results was performed using SPSS version 15.0 (Chicago, IL, USA). RESULTS: The result of the Student's t test indicated no significant differences (p > 0.05) between the normalized values of the ensemble average obtained in masticatory cycles in both groups. CONCLUSION: Based on the results of this study, it was concluded that individuals with osteoporosis did not show significantly lower masticatory cycle performance and efficiency compared to control subjects during the habitual and non-habitual mastications. This result is very important because it demonstrates the functionality of the complex physiological process of mastication in individuals with osteoporosis at the bones that compose the face.

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.

Adhesive bond strength between a ceramic system and composite resin bonded by resinous cement submitted or not to thermocycling process.

AIM: The success of ceramic restorations is influenced by biocompatibility and resistance provided after bonding with an adhesive system. The aim of this in vitro study was to evaluate the adhesive bond strength between ceramic (IPS Classic V, Ivoclar Vivadent) and composite resin (Z-250, 3M), submitted or not to thermocycling treatment. METHODS: Forty ceramic cylinders were obtained with the following dimensions: 2 mm diameter and 3 mm high. The bond surface was polished with polishing paper (#600), conditioned with 10% hydrofluoric acid and silanized, according to manufacturer's recommendations. Later, the ceramic cylinders were bonded, with resinous cement (Rely X, 3M) to composite resin cylinders (Z-250, 3M) with the same dimensions, under 1 kg load. The assemblies were divided into two groups submitted to the following treatments: Group 1 (control): immersed in distilled water at 37 degrees C for 3 days, and Group 2: thermocycled (500 cycles) into two baths (5 degrees C and 55 degrees C), with 1 min of storing time each. In order to evaluate the adhesive resistance, the assemblies were tractioned in a universal testing machine (EMIC MEM 2000) with a crosshead speed of 0.5 mm/min. Obtained data were submitted to statistical analysis (ANOVA and Tukey's test). RESULTS: The means (MPa) and standard deviation obtained for Groups 1 and 2 were, respectively, 29.64+/-9.48 and 17.55+/-4.78. Group 1 presented significantly higher values than Group 2 (P<0.05). CONCLUSION: The results obtained in this study showed that the thermocycling procedure decreased the adhesive resistance between the materials studied.

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 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.