Activity Of Temporal Muscles Research Articles

Correlations between masticatory muscle activity, quality of life, and dysfunction severity in women with chronic temporomandibular disorder

ABSTRACT BACKGROUND AND OBJECTIVES: Assessing the possible interactions between the activity of masticatory muscles and quality of life and severity of the temporomandibular disorder can help clarify how changes in muscle activity can be associated with a chronic temporomandibular disorder in women. This study aimed to investigate the correlations between masticatory electrical activity during mandibular resting, maximum voluntary contraction, the severity of the temporomandibular disorder, and quality of life in women with chronic temporomandibular disorder and to compare these parameters with healthy asymptomatic controls. METHODS: Sixty women, 30 with temporomandibular disorder and 30 asymptomatic, participated in this case-control observational study. Diagnostic Criteria for Temporomandibular Disorder was used to identify the presence or absence of temporomandibular disorder. The SF-36 questionnaire was used to assess the quality of life in participants, and ProTMDmulti-part-II was applied to assess the severity of signs and symptoms of temporomandibular disorder. RESULTS: During jaw clenching, the masticatory activity of the right temporal and left masseter muscles, the symmetry of the masseter muscles, and anteroposterior coefficient were significantly smaller in the temporomandibular disorder group than in the asymptomatic group. Masticatory activity at rest, signs and symptoms of chronic temporomandibular disorder, and impairment of the quality of life were correlated using Spearman coefficient (p<0.05). CONCLUSION: Our results contribute to findings on the associations between the masticatory activity in chronic signs and symptoms of the temporomandibular disorder, impairment in quality of life, and differences in the masticatory activity during clenching in patients with temporomandibular disorder and controls.

Anterior open bite due to temporomandibular joint osteoarthrosis with muscle dysfunction treated with temporary anchorage devices

Skeletal Class II high-angle open bite is often accompanied by osteoarthrosis of the temporomandibular joint (TMJ-OA). This type of malocclusion is challenging to correct, and it has been reported that patients with TMJ-OA treated with orthognathic surgery often experience skeletal relapse and a poor prognosis. This case report describes the treatment of a 25-year-old woman with retrognathia and TMJ-OA, whose masseter and temporal muscle activities were weak. Temporary anchorage devices were placed in the maxilla and the mandible, and the first molars were intruded. We used improved superelastic nickel-titanium alloy wires with tip-back bends for both arches, and intermaxillary elastics were used to upright the molars. After treatment, intrusion of the maxillary and mandibular first molars, counterclockwise rotation of the mandible, and improvement of occlusion and profile had been achieved. The patient's condyles were repositioned into ideal positions, and masticatory muscle activity was augmented and balanced. After 2years of retention, the mandibular and condylar positions were stable, and acceptable occlusion was maintained without recurrence of TMJ symptoms; harmonious activity of the masticatory muscles was retained. The findings of this case report suggest that molar intrusion using temporary anchorage devices for a patient with severe anterior open bite and TMJ-OA may be useful for improving stomatognathic function, occlusion, and facial esthetics.

Association Between Contact from an Overerupted Third Molar and Bilaterally Redistributed Electromyographic Activity of the Jaw Closing Muscles

To determine whether the facial side of an overerupted third molar and/or the side exhibiting symptoms of temporomandibular disorders (TMD) has an association with the bilateral distribution of occlusal contact number, occlusal force, or surface electromyographic (SEMG) activity of the anterior temporalis (TA) and masseter muscles. Nineteen patients with unilateral TMD symptoms and one overerupted mandibular third molar were enrolled. Occlusal contacts and the SEMG activity of the anterior temporalis and masseter muscles were recorded simultaneously during maximal voluntary clenching (MVC) in the intercuspal position (ICP-MVC) and in the protrusive edge-to-edge position (Pro-MVC). The associations between the side of overeruption/TMD symptoms and the Δvalues of the differences between the right- and left-side values for the number of occlusal contacts, sectional force value (defined as the ratio of the anterior or posterior sectional arch bite force of the right or left side to the total arch force [SFV]), and SEMG activity of the temporalis and masseter muscles were analyzed. The overeruption side (P < .050), but not the symptomatic side (P > .050), showed an association with the Δvalues, with higher SFVs of the posterior arch and lower values for temporalis SEMG activity in the 100%, 75%, and 50% protrusive clenching positions and larger numbers of occlusal contacts in the posterior arch in the 100% and 75% protrusive clenching positions than the non-overeruption side. The pattern of occlusion, but not TMD symptoms, had an association with the number and distribution of the occlusal contacts, occlusal force, and temporalis SEMG activity.

Effect of Different Denture Base Material on Electromyographic Activity in Maxillary Single Denture Wearers

Aim of study: was to evaluate and compare the effect of three different denture base material (heat cured acrylic resin, cast metal base and thermoplastic resin) on electromyographic activity of masseter and temporalis muscles in maxillary single denture wearers. Material and methods: Ten completely maxillary edentulous patients were selected with ages ranged from 55-60 years. All patients had received heat cured acrylic resin single maxillary complete denture (Group І) then replacing the denture base through rebasing procedures by cobalt chromium (Co-Cr) (Group ІІ) then thermoplastic resin material (Group ІІІ). All patients were instructed to use their resin dentures for equal periods of three months when EMG records of muscles of mastication (masseter and temporalis) were obtained at insertion then patient recalled after one month and at the end of three months , period of two week interval was left between each group as a washing period. Results: The results of this study showed that there were a significant differences between them, as the thermoplastic resin (group ІІІ) was the best followed by cobalt chromium denture (group ІІ) then heat cured acrylic resin denture base (group І) .Conclusion: EMG activity affected by maxillary denture base material as the lesser effort of masticatory muscles was done by using thermoplastic resin denture base rather than Co-Cr or acrylic resin denture base.

Assessment of Mandibular Surface Area Changes in Bruxers Versus Controls on Panoramic Radiographic Images: A Case Control Study.

Background:Bruxism is the commonest of the many parafunctional activities of the masticatory system. Opinions on the causes of bruxism were numerous and widely varying. It can occur during sleep as well as wakefulness. Bruxism was for long considered a major cause of tooth wear. Other effects of bruxism may include tooth movement and tooth mobility, as well as changes in oral soft tissues and jaw bone. Since the exact etiology and manifestations are unclear, it was difficult to diagnose Bruxism. In this study, we evaluated the area change as measured from digital panoramic radiographs that can occur in the lower jaw bone in those with Bruxism and compared the results with non-bruxers.Aims and Objective:To determine the surface area changes of the mandible, condylar and coronoid processes in Bruxers from Panoramic radiographs and to compare and contrast the changes with age and gender matched controls.Materials and Methods:The study was conducted in the department of Oral Medicine and Radiology. The total sample size was 40. The sample was divided into two groups, Bruxers and non-bruxers with 20 subjects in each group. Healthy volunteers aged between 20- 30 years diagnosed with Bruxism and Healthy volunteers aged between 20- 30 years diagnosed without Bruxism were included in group II (Non-Bruxers). Bruxchecker was made use of in confirming the Bruxism in Group I. The Panoramic radiograph was used as the imaging modality for the study. The measurements were made with the help of software, Image J. All the measurements were tabulated and statistical analysis was made using ANOVA (Post hoc) followed by Dunnett’s test and unpaired t test.Results:A comparison of the mandibular surface area as a whole and also condylar and coronoid processes individually were carried out. Significant results were obtained in case of condylar and coronoid processes between the two groups. The surface area of condylar process of Group I was found to be lower than that of Group II. The surface area of the right coronoid process of group I was found to be less when compared to that of group II but the values of the left coronoid process of group I was found to be more when compared with group II. The surface area of the mandible showed no significant difference between the groups. There was significant difference between the genders in case of mandible, condyle and coronoid. The surface area of mandible and condylar process was found to be lower in female when compared to male. The surface area of coronoid process was found to be more in case of females when compared to that of males in Group I.The results of our study show that while the overall surface area of bruxers remain unaffected when compared to controls, the condylar and coronoid process show significant change. The hitherto belief that the primary brunt of bruxism is borne by the masseter would require a revisit since alteration in tonicity of the masseter would reflect in surface area change of the mandible as a whole. An increase in the surface area of the coronoid process in bruxers was observed in our study which could be attributed to altered activity of the temporalis, a muscle largely responsible for the posture of the mandible. This could imply that bruxers show alteration in temporalis activity which would explain several clinical manifestations such as headache, neck pain, shoulder pain and altered posture and so on which we have observed in the clinical practice of neuromuscular dentistry. Further studies examining the activity of the temporalis and masseter would further corroborate our findings and form the basis for future research in this arena.Conclusion:This original research was carried out to assess the surface area changes in mandible and condylar and coronoid processes of Bruxers and non-bruxers. The results showed significant changes in the surface area of condylar and coronoid process in Bruxers when compared to the controls. This is an area of study with paucity of available literature. This study would be a stepping stone for future studies in this arena.

Relation between Headache and Mastication Muscle Tone in Adolescents.

Headache is a common problem in the population, which decreases the quality of life and makes everyday functioning difficult. It often coexists with typical symptoms of temporomandibular disorders. The objective of the study was to clarify whether there is a relationship between the presence of headache in young volunteers and the mastication muscle tone. Material and Method. Volunteers aged 18 years who underwent general dental examination, clinical evaluation, and examination using the dual-axis diagnostic system Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) form in the Polish language version participated in the study. On the basis of the examination results, these individuals were divided into three groups according to RDC results. A group of healthy individuals (axis I value 0), a group of sick individuals (axis I diagnosis Ia, IIa, or IIIa), and a group of individuals suffering from depression (axis II values 1–3) were singled out. Then, volunteers were divided into two groups: group I reporting headache and group II without any pain. In each of these individuals, the contractile activity of the masseter muscles and anterior temporal muscles was recorded bilaterally as the surface electromyographic activity (sEMG) at rest, during swallowing, and maximum clenching. The activity index ranging between +100 (activity of the masseter muscles only) and −100 (activity of the anterior temporal muscles only) was used to indicate the predominance of activity of the study muscles. Results. The statistical analysis of data showed that there was a significant relationship between the presence of headache and a change in the mastication muscle tone, expressed as the predominant activity of the temporal muscles, only in the group of sick individuals during maximum clenching. Summary. The diversity of sEMG results implies that a change in the mastication muscle tone is not a direct consequence of headache, but it has to be modified by other factors.

Electromyographic Activity of the Masseter and Temporal Muscles in Patients With Nonsyndromic Complete Unilateral Cleft Lip and Palate: 2-Stage Versus 1-Stage Palate Repair.

To assess the electromyographic activity of the masseter and temporal muscles in cleft patients who underwent 1-stage palate repair versus 2-stage palate repair. Thirty-two patients with nonsyndromic complete unilateral cleft lip and palate operated by 2 different protocols for palate repair, 1-stage (group 1, n = 16) versus 2-stage with delayed hard palate closure (group 2, n = 16) were available in the retrospective longitudinal study. Standardized electromyographic records of the masseter and anterior portion of temporal muscles were obtained with 2 repetitions during mastication and rest. No statistically significant (all P > 0.05) differences were observed in the electromyographic data between the groups 1 and 2. There were similar electromyographic activity of masseter and temporal muscles during mastication and at rest after 1- and 2-stage palate closure.

Effect of Breast Cancer Treatment on the Stomatognathic System.

Breast cancer is the most common cancer affecting women in the world and provides functional changes in the human body. Evaluate women submitted to unilateral mastectomy, through electromyographic activity (mandibular rest, right and left laterality, protrusion, maximum voluntary contraction with and without Parafilm, habitual and non-habitual mastication) and thickness (rest and maximum voluntary contraction) of the right temporal muscle (RT), left temporal (LT), right masseter (RM) and left masseter (LM), also the molar bite force (right and left) and compare the data with healthy women. Material and Methods: 32 women were divided into two groups: unilateral mastectomy group (MG), average ± standard deviation 56.50±14.50 years (n=16) and without the disease group (CG), average ± standard deviation 56.56±14.15 years (n=16). The normalized electromyographic data, muscle thickness and maximal molar bite force were tabulated and submitted to statistical analysis (SPSS 21.0; student t test, p≤0.05). Significant statistical differences between MG and CG were found in right laterality, for RM (p=0.02); left laterality, for LT (p=0.01); chewing with peanuts, for RM (p=0.04); chewing with raisins, for LM (p=0.04) and right molar bite force (p=0.03). There was no statistically significant difference between MG and CG for muscle thickness. The results of this study suggest that women undergoing unilateral mastectomy may present functional changes, with emphasis on muscular hyperactivity, lower masticatory efficiency and lower maxillary bite force.

Preliminary approach for the surface electromyographical evaluation of the oral phase of swallowing.

Swallowing is a muscular activity that occurs both after mastication and spontaneously as a result of saliva accumulation. Spontaneous saliva swallowing occurs about every 2minutes. Comprehension of its functional mechanisms is relevant to assess their modification in clinical situations. A standardised surface electromyographical (ssEMG) protocol for the evaluation of this muscle activity is lacking. Aims of the present study are: (i) to determine the reproducibility of a ssEMG protocol for the evaluation of the oral phase of saliva swallowing and (ii) to evaluate the activity of masseter (MM), anterior temporalis (TA), submental muscles (SM) to draw a reference model of swallowing. Standardised surface electromyographical activity of MM, TA and SM during swallowing of saliva spontaneously accumulated was recorded in 20 healthy participants. Functional indexes including symmetry (POC), recruitment (Impact), duration of activation of each couple of muscles and of the whole exercise, position, intensity of the spike were computed. Inter- and intra-appointment reliabilities were assessed and method errors calculated. Descriptive statistics, sex- and muscles-related comparisons were carried out. Standardised surface electromyographical assessment of MM, TA and SM muscles was reliable. A high inter-individual variability was found. Percentage overlapping coefficient (POC) values were close to 80% for TA and SM, higher than for MM (P<.001). Impact values ranged between 16.4% and 30.7%, and differences were found between muscles (P<.001). The global muscle activity during swallowing lasted between 1.5 and 1.8seconds. For each couple of muscles, the duration of activation ranged between 0.7 and 1.6seconds and muscles-related differences were found (P<.001). The spike of activation for each couple of muscle ranged between 35.7% and 44.2% of the duration. The protocol was reliable and intra-participants repeatable measures can be carried out. Due to the high inter-participants variability, further analyses are needed to draw a model of muscular activity.

Chronic stress and temporalis muscle activity in TMD patients and controls during sleep: a pilot study in females.

The aim of this study was to assess the correlation between chronic stress and temporalis muscle activity during four nights. Forty-four female subjects were recruited in five dental practices located in different areas of the federal state of Saarland, Germany (dental practice network in Saarland). The following inclusion criteria were used: female, aged between 18 and 65, no somatization or depression, and no pain medication, graded chronic pain status < 3. Both subjects reporting about sleep bruxism and subjects negating sleep bruxism during anamnesis were included. Anamnestic issues, sleep bruxism, anxiety, and chronic stress were assessed using validated questionnaires. Temporalis muscle activity was measured for four nights using a portable electromyographic device. Correlation coefficient was used to assess the correlation (Spearman-correlation) between chronic stress and number of temporalis muscle episodes/hour and between anxiety and the number of episodes/hour. The analysis showed that the factors "work overload" (adulthood chronic stress because of too many demands at work) and "pressure to perform" (necessity to be successful at work) were significantly correlated with the number of temporalis muscle episodes per hour. In contrast, anxiety was not correlated with temporalis muscle episodes per hour. Work-related chronic stress seems to be associated with an increased level of temporalis muscle activity during sleep. During anamnesis, work-related aspects should be assessed in females presenting with sleep-bruxism.

Swallowing and Temporomandibular Disorders in Adults.

Temporomandibular disease (TMD) etiology is multifactorial and is related to many perpetuating, predisposing, and initiating factors. The daytime parafunctions may have an important role in TMD pathogenesis. The most frequent parafunctions analyzed were the static parafunction (ie, clenching) and the dynamic parafunction (ie, grinding). In the present paper, the authors evaluated the swallowing (an oral function/parafunction) with the surface electromyography in patients with TMD. Twenty patients with TMD problems (nonhealthy patients, NHP) (mean age: 33 ± 1.994; 8 men and 12 women) and 20 healthy matched subjects (HP) (34.4 ± 2.782; 6 men and 14 women) were selected and examined. On each patient, an 8-channel surface electromyography was done during saliva swallowing. Nonhealthy patients presented higher masseter and temporalis activation (P < 0.05) and an unbalancing of temporalis and submental muscles activation (P < 0.05) than the HP. Nonhealthy patients presented a time of swallow higher than HP (P < 0.001). Nonhealthy patients presented a higher muscles activation and time of swallow than HP and a decrease of muscles balancing activation.

ELECCTROMYOGRAPHIC EVALUATION OF CANINE GUIDANCE OCCLUSION AND BILATERAL BALANCED OCCLUSION IN THERMOPLASTIC COMPLETE DENTURES

The purpose of this study was to evaluate the effect of two occlusal schemes; canine guidance occlusion and bilateral balanced occlusion on the masseter and temporalis muscle activity in thermoplastic complete dentures. Ten male completely edentulous patients whose ages ranged from 55 to 70 years were selected. Half of the selected patients received a thermoplastic complete denture with canine guidance occlusal scheme and the other half of the patients received a thermoplastic complete denture with bilateral balanced occlusal scheme. Electromyographic evaluation of the masseter and temporalis muscles, during chewing banana, peanut and carrot, was conducted on the patients after using their dentures for one month. Each occlusal scheme was then converted into the other scheme using the same dentures, and the procedure of evaluation was repeated after another one month. The data were collected, tabulated and analyzed by using Paired sample t-test. The results of this study showed that there was no significant difference between the canine guidance occlusal scheme and the bilateral balanced occlusal scheme in the electromyographic activity of both masseter and temporalis muscles during chewing all test foods. It was concluded that both bilateral balanced occlusion and canine guidance occlusion can be used successfully in thermoplastic complete dentures without affecting the masseter or temporalis muscle activity.

Design and Evaluation of Smart Glasses for Food Intake and Physical Activity Classification.

This study presents a series of protocols of designing and manufacturing a glasses-type wearable device that detects the patterns of temporalis muscle activities during food intake and other physical activities. We fabricated a 3D-printed frame of the glasses and a load cell-integrated printed circuit board (PCB) module inserted in both hinges of the frame. The module was used to acquire the force signals, and transmit them wirelessly. These procedures provide the system with higher mobility, which can be evaluated in practical wearing conditions such as walking and waggling. A performance of the classification is also evaluated by distinguishing the patterns of food intake from those physical activities. A series of algorithms were used to preprocess the signals, generate feature vectors, and recognize the patterns of several featured activities (chewing and winking), and other physical activities (sedentary rest, talking, and walking). The results showed that the average F1 score of the classification among the featured activities was 91.4%. We believe this approach can be potentially useful for automatic and objective monitoring of ingestive behaviors with higher accuracy as practical means to treat ingestive problems.

EEG-like signals can be synthesized from surface representations of single motor units of facial muscles

Electrodes for recording electroencephalogram (EEG) are placed on or around cranial muscles; hence, their electrical activity may contaminate the EEG signal even at rest conditions. Due to its role in maintaining mandibular posture, tonic activity of temporalis muscle interferes with the EEG signal particularly at fronto-temporal locations at single motor unit (SMU) level. By obtaining surface representation of a motor unit, we can evaluate its interference in EEG and if we could sum surface representations of several tonically active motor units, we could estimate the overall myogenic contamination in EEG. Therefore, in this study, we followed re-composition (RC) approach and generated EEG-like artefact model using surface representations of single motor units (RC). Furthermore, we compared signal characteristics of RC signals with simultaneously recorded EEG signal at different locations in terms of power spectral density and coherence. First, we found that RC signal represented the power spectral distribution of an EMG signal. Second, RC signal reflected the discharge rate of a SMU giving the greatest surface representation amplitude and strongest interference appeared as distinguishable frequency peak on RC power spectra. Moreover, for strong interferences, RC also contaminated the EEG at F7 and other EEG electrodes. These findings are important to illustrate the susceptibility of EEG signal to myogenic artefacts even at rest and the research using EEG coherence comparisons should consider muscle activity while drawing conclusions about neuronal interactions and oscillations.

Electromyographic Analysis of Masticatory Muscles in Cleft Lip and Palate Children with Pain-Related Temporomandibular Disorders.

Aim The aim of this study was to assess the electrical activity of temporalis and masseter muscles in children with cleft lip and palate (CLP) and pain-related temporomandibular disorders (TMD-P). Methods The sample consisted of 31 CLP patients with a TMD-P (mean age 9.5 ± 1.8 years) and 32 CLP subjects with no TMD (mean age 9.2 ± 1.7 years). The children were assessed for the presence of temporomandibular disorders (TMD) using Axis I of the Research Diagnostic Criteria for TMD (RDC/TMD). Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) in the mandibular rest position and during maximum voluntary contraction (MVC). Results The rest activity of the temporalis and masseter muscles was significantly higher in TMD-P group compared with non-TMD children. A significant decrease in temporalis muscle activity during MVC was observed in TMD-P patients. There was a significant increase in the Asymmetry Index for temporalis and masseter muscle rest activity in the TMD-P group. Conclusion Cleft children diagnosed with TMD-P have altered masticatory muscle activity, and this can affect their muscle function.

Electromyographic activity of superficial masseter and anterior temporal muscles during unilateral mastication of artificial test foods with different textures in normal subjects

Electromyographic activity of superficial masseter and anterior temporal muscles during unilateral mastication of artificial test foods with different textures in normal subjects

ElectromyoFigureic Evaluation of Functional Adaptation of Patients with New Complete Dentures.

Objective The objective of this study was to evaluate the level of adaptation of patients to newly fitted complete dentures in their dominant and nondominant sides, by means of ElectromyoFigureic signals. Materials and Methods Eighty-eight patients with complete dentures were evaluated in the study. Masticatory muscle (masseter and temporal) bioelectric activity of the patients with complete dentures was recorded at maximum intercuspal relation. Parametric statistical data were analyzed with one-way repeated measures ANOVA test. Results Measurement time was significantly different for both dominant (DS) and nondominant (NDS) sides: FΣs-DS = 21.51, p=0.0001; FΣs-NDS = 13.25, p=0.0001. Gender was also significantly different: FΣs-DS-gender = 41.53, p=0.001; FΣs-NDS-gender = 85.76, p=0.0001. The average surface area values showed significant difference in females. Prior experience with dentures showed no significant difference for both sides of mastication: FΣs-DS-experiences = 1.83, p=0.1772; F Σs-NDS-experiences = 3.30, p=0.0697. Conclusion The planimetric indicators of bioelectric activity of masseter and temporalis muscles at maximum physiological loading conditions are significant discriminators of the level of functional adaptation of patients with new complete dentures.

Comparative Study of Implant Supported Overdenture Retained with Two Types of Attachments

Objectives: This study was conducted to compare implant retained mandibularoverdenture with two different attachments (ball and socket and locator).Subject and methods:7 edentulous patients were selected according to certain criteria.Each patient received two platform switched implants placed in the mandibular canine-premolar region bilaterally. GROUP I: Locator attachments were used to retain the implant-supported overdentures. Locator abutments were loaded after 2-3 months. All patients received conventional maxillary dentures. After follow up periods we removedthe attachment with wash period 1month then we used ball and socket attachmentGROUP II. The two groups were evaluated for retention, masticatory efficiency and EMG at 0, 3 and 6 months after loading of each attachment. Results: regarding the effect of time on retention of both groups in ball group there was a significant increase in retention at base line till 3 months and decrease from 3-6 months, while locator group there was increase of retention through all periods. Regarding the effect of time on both groups the masticatory efficiency of both ball and locator group have no significant difference through all periods. Comparing the two groups the masticatory efficiency has no significant difference except on chewing carrots the numbers of strokes till first swallow increase in ball group, and on chewing peanut after 6 months the ball group show higher time till first swallow than locator as well as the time to empty mouth. Regarding the effect of time on both groups the electromyographic activity of both masseterand temporalis muscles has no significant difference through all periods except in locator group decrease the activity of masseter after 3 months. Conclusions: the ball attachment at the beginning has a higher retention quality than locator attachment, by time ball attachment loss some of its retention rather than locator attachment. The electromyographic activities and the masticatory efficiency of temporalis and masseter muscles of both ball attachment and locator attachment were comparable.

25. Evaluation of electromyographic activity of temporalis, masseter, digastric and sternocleidomastoid muscles in surgically managed temporomandibular joint trauma cases

25. Evaluation of electromyographic activity of temporalis, masseter, digastric and sternocleidomastoid muscles in surgically managed temporomandibular joint trauma cases

The electrical activity of the masticatory muscles in children with cleft lip and palate.

Information regarding masticatory muscle function in children with cleft lip and palate (CLP) is limited. As a consequence, research on masticatory muscle activity in cleft subjects is needed. To assess masticatory muscle activity in children surgically treated for CLP as well as identify the possible factors associated with this activity. The sample comprised 82 children with mixed dentition and Class I occlusions (25 children with unilateral CLP and 57 subjects with no cleft abnormalities). A DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) was used to take electromyographical (EMG) recordings of the temporal and masseter muscles both in the mandibular rest position and during maximum voluntary contraction (MVC). Patients with clefts showed a significant increase in temporal muscle activity at rest compared with the controls. The presence of clefts and unilateral posterior crossbites are factors strongly associated with increased temporal muscle EMG potentials during rest position. Children with clefts have altered temporal muscle function. The presence of posterior crossbites affects the temporal muscle activity in cleft subjects. Early diagnosis and orthodontic treatment of malocclusions are necessary to achieve functional improvement in these patients.