Anterior Temporalis Research Articles

Surface electromyographic evaluation of jaw muscles in children with unilateral crossbite and lateral shift in the early mixed dentition. Sexual dimorphism

Objectives: To examine the activity of jaw muscles at rest and during maximal voluntary clenching (MVC) in children with unilateral posterior crossbite (UPXB) and functional lateral shift in the early mixed dentition and to evaluate sex differences. Material and Methods: The sample included 30 children (15 males, 15 females) aged 6 to 10 years old, with UPXB and functional mandibular lateral shift (≥1.5 mm) in the early mixed dentition. sEMG activity coming from the muscle areas (anterior temporalis [AT], posterior temporalis [PT], masseter [MA] and suprahyoid [SH]) were obtained from both the crossbite (XB) and noncrossbite (NONXB) sides at mandibular rest position. sEMG acti-vity of the bilateral AT and MA muscles sides was obtained during MVC. Asymmetry and activity indexes were calculated for each muscle area at rest and during MVC; the MA/TA ratio during MVC was also determined. Results: At rest, no differences were found between sexes for any muscle areas or asymmetry and activity indexes. No differences were found between XB and NONXB sides. During MVC, however, significant sex differences were found in AT and MA activity, with higher sEMG values in males than in females, on both XB and NONXB sides. Asymmetry indexes, activity indexes and MA/AT ratios did not show significant differences between the sexes. Activity was symmetric both in males and in females. Conclusions: At rest, no sex differences were found, but during MVC males showed higher activity than did females in both XB and NONXB AT and MA muscle areas. Muscular activity was symmetrical at rest and during MVC in both sexes. Sexual dimorphism should be considered in the diagnosis and treatment of UPXB and lateral shift in the early mixed dentition. Key words:Unilateral crossbite, mandibular shift, jaw muscles, sEMG, early mixed dentition.

The influence of different registration techniques on condyle displacement and electromyographic activity in stomatognathically healthy subjects: A prospective study

It is unclear whether different intermaxillary registration techniques are related to a physiological condylar position that permits neuromuscular equilibrium. This study analyzes and quantifies the effects of different registration techniques on the condyle position and how the registration technique modulates bilateral masseter and anterior temporalis muscle electromyographic activity. Three-dimensional electronic condylar position analysis (EPA) with an ultrasound-based jaw-tracking system and surface electromyographic activity (sEMG) was recorded during the registration of a manually guided centric relation (CR), maximal intercuspation (MI), and Gothic arch tracing guided centric relation (DIR method). Participants were 26 stomatognathically healthy volunteers (mean age, 30.6 ±9.5 years). Data were analyzed by 1-way ANOVA and post hoc Bonferroni correction (α=.05). EPA showed significant differences (P<.001) for CR, MI, and DIR in the vertical, sagittal, and horizontal axes. The condyle position during DIR was found to be significantly more anteriorly and inferiorly located than with CR (P<.001) and MI (P<.04). There were no significant differences in the mean muscle activity among CR, MI, and DIR. Muscular symmetry ranged from 63.87 to 81.47%. Significantly higher symmetry for the anterior temporalis (P=.03) and the masseter (P=.03) was found during the DIR than with CR. Torque coefficients (potential laterodeviating effect) were between 88.02% (CR) and 89.94% (MI). Registration technique significantly influenced the condyle position, while mean muscular activity was minimally affected. With respect to muscular balance and activation, the DIR position proved to be capable of inducing the greatest motor unit activity when compared with manually guided CR and MI.

Immediate Effect of Occlusal Errors on Masticatory Muscle Activity in Denture Wearers: A Pilot Study

ABSTRACT Over the past three decades, little scientific progress has been made relative to occlusion in conventional complete dentures. Equal distribution of functional load throughout the residual denture foundation is likely an important factor in prosthesis stability and patient acceptance of dentures. A better understanding the relationship between denture occlusion and the physiologic behavior of muscles involved in mastication may prove beneficial in the clinical management of edentulism. The purpose of the present study was to determine the short-term immediate effects of unilateral and bilateral posterior occlusal interferences on masticatory muscle activity in edentulous patients treated with conventional complete dentures. Bilateral EMG activity of the anterior temporalis and masseter muscles was recorded in ten subjects at baseline, following introduction of unilateral posterior occlusal interferences, and following introduction of bilateral posterior interferences. During each experimental event, muscle activity was recorded bilaterally at maximal clench and the intended denture occlusion was electronically verified. Patients responded to questionnaires after each experimental intervention and following removal of occlusal interferences. Student's paired t-test was used to compare the data obtained (p = 0.05). Results indicate no significant difference in EMG values at baseline, after introduction of bilateral posterior interferences, after the introduction of unilateral right posterior interferences and after removal of the occlusal interference. In the group with unilateral left posterior occlusal interferences there was a significant reduction in the EMG activity of the left masseter. Analysis of questionnaires did not reveal any significant findings. Taken together, results suggest that there was no significant difference in the EMG values of the patient after the introduction of the posterior interferences. How to cite this article Ahuja S, Wicks R, Cagna D, Brandt R, Scarbecz M. Immediate Effect of Occlusal Errors on Masticatory Muscle Activity in Denture Wearers: A Pilot Study. Int J Exper Dent Sci, 2012;1(1):1-7.

Changes in the Bilateral Balance of Masticatory Muscle Activity after Surgical Correction of Mandibular Lateral Shift: Report of 2 Cases

Objective: This case report is designed to present changes in the bilateral balance of masticatory muscle activity during daytime after surgical correction of mandibular lateral shift. Study design: Using a portable EMG recording system, masseter and anterior temporal muscle activities were recorded in two patients with lateral deviation of the mandible for three hours at pretreatment, 6 months and 12 months after surgery. Results: In case 1, the Asymmetry Ideex of masseter muscle activity during mealtime and during daytime was 0.3 at T0, 0.4 at T1and 0.1 at T2, and -0.6 at T0, 0 at T1and 0.2 at T2, respectively. With respect to anterior temporal muscle activity, the AIs were -0.1 and -0.4 at T0, -0.2 and -0.5 at T1, and 0.1 and -0.1 at T2 during mealtime and daytime. In case 2, the AI of masseter muscle activity during mealtime and during daytime was 0.3 at T0, 0.2 at T1and 0.3 at T2, and -0.3 at T0, -0.6 at T1 and -0.1 at T2, respectively. With respect to anterior temporal muscle activity, the AIs were 0 and 0 at T0, 0 and 0.3 at T1, and 0.1 and 0.3 at T2 during mealtime and daytime. Conclusion: The different differing results were shown in two similar cases, although despite the surgical correction of mandibular lateral shift producing produces considerable improvement of the bilateral balance in muscle activity during mealtime and daytime.

Effect of occlusal splint thickness on electrical masticatory muscle activity during rest and clenching

The extent of separation between the maxillary and mandibular teeth in the fabrication of interocclusal splints designed to achieve efficiency and muscle relaxation is controversial and undefined in the literature. Based on this premise, the aim of this study was to evaluate the effect of interocclusal splint thicknesses of 3 and 6 millimeters on the electrical activity of the anterior temporal and masseter muscles during rest and dental clenching. Twenty asymptomatic individuals (10 males and 10 females) were selected using the Research Diagnostic Criteria (RDC). Electromyography (EMG) was performed both with and without the 3- and 6-mm splints using the Bio EMG software package, which recorded values given in microvolts (µV). The results, which were assessed using analysis of variance (ANOVA) to a 5% significance level (p < 0.05), showed increased electrical activity of the masticatory muscles during dental clenching compared with at rest, with greater activity in the masseter muscle. The electrical activity did not differ according to the thickness of the splints or between males and females. We can conclude that both splint thicknesses are effective in treating muscle hyperactivity given their similar clinical behavior for asymptomatic individuals.

Neuromuscular adaptations with flexible fixed functional appliance – a 2-year follow-up study

To evaluate long-term neuromuscular adaptation with the flexible fixed functional appliance. Electromyography (EMG) was performed on 15 young, growing females with Class II Division 1 malocclusion treated with a flexible fixed functional appliance. Bilateral EMG activity from the anterior temporalis and masseter muscles was monitored longitudinally to determine changes in posture, swallowing, and maximum voluntary clenching during a 24-month observation period. There was a significant decrease in EMG activity during saliva swallowing (p < 0.05) and maximum clenching (p < 0.05 at 3months and p < 0.01 at 1month after treatment); this persisted for up to 1month but gradually returned to pre-appliance levels near the end of 6 months. It remained stable from then on until the end of the observation period (24months). The anterior temporalis and masseter muscles clearly responded to appliance therapy. The neuromuscular adaptation documented after 6months of treatment remained stable over a 24-month observation period.

Anterior Temporalis and Suprahyoid EMG Activity During Jaw Clenching and Tooth Grinding

The aim of this study was to evaluate the anterior temporalis and suprahyoid electromyographic (EMG) activity during jaw clenching and tooth grinding at different jaw posture tasks. The study included 30 healthy subjects with natural dentition and bilateral molar support, incisive protrusive guidance and bilateral laterotrusive canine guidance. Bipolar surface electrodes were located on the right anterior temporalis and suprahyoid muscles. Three EMG recordings in the standing position were performed in the following tasks: C. clenching in the intercuspal position (IP); P1. eccentric grinding from IP to protrusive edge-to-edge contact position; P2. clenching in protrusive edge-to-edge contact position; P3. concentric grinding from protrusive edge-to-edge contact position to IP; L1. eccentric grinding from IP to laterotrusive edge-to-edge contact position; L2. clenching in laterotrusive edge-to-edge contact position; L3. concentric grinding from laterotrusive edge-to-edge contact position to IP. EMG activity during protrusive and laterotrusive tasks was lower than intercuspal position in the anterior temporalis, whereas an opposite EMG pattern was observed in the suprahyoid muscles activity, excepting recorded activity in L2 (mixed model with unstructured covariance matrix). Anterior temporalis activity was higher during P3 than P1 and P2 tasks and during L3 than L1 and L2 tasks, whereas in the suprahyoid muscles, activity was higher during P1 than P2 tasks and during L1 than L2 and L3 tasks. These results could support the idea of a differential modulation of the motor neuron pools of anterior temporalis and suprahyoid muscles of peripheral and/or central origin.

CIRNE III Abstracts: Congresso Internacional de Reabilitação Neuromusculoesquelética e Esportiva, May 18–21, 2011, Vitória, Brazil

CIRNE III Abstracts: Congresso Internacional de Reabilitação Neuromusculoesquelética e Esportiva, May 18–21, 2011, Vitória, Brazil

SEMG activity of masticatory, neck, and trunk muscles during the treatment of scoliosis with functional braces. A longitudinal controlled study

Background Studies on the relationship between occlusal problems and the spine are of increasing interest. In this study, we monitored the sEMG activity of masticatory, neck, and trunk muscles during the treatment of scoliosis in young patients, and compared the data with a control of untreated group. Subjects and methods Twelve white Caucasian patients (nine males and three females; mean age of 8.0 ± 1.5 years) with scoliosis and Class I occlusion (without crowding) were included in this study (study group). Fifteen healthy subjects (nine males and six females; mean age of 9.5 ± 0.8 years) were recruited as control group. The subjects were visited before they underwent the treatment of scoliosis, as well as after 3 (T1) and 6 months (T2) of their treatment for scoliosis. The patients were instructed to wear the device during sleep and during the day, according to the protocol given by their orthopedic. Results The treated group showed statistically significant changes in the sEMG activity of masticatory, neck, and trunk muscles, both at rest and during MVC of the mandible with respect to T0. The masseter and the anterior temporalis showed a significant improvement in the asymmetry index from T0 to T2. On the other hand, subjects in the control group did not register much change. Conclusion Our findings suggest that the use of a functional device for the treatment of scoliosis induces a significant reduction in the asymmetry index of the trunk muscles, as well as a significant increase in the contractility of masticatory muscles.

Temporomandibular disorder and generalized joint hypermobility: electromyographic analysis of the masticatory muscles

Aim: This study aimed to verify the presence of generalized joint hypermobility (GHJ) in individuals with temporomandibular disorders (TMD) and asymptomatic individuals and to compare the activity of their masticatory muscles. Methods: 61 female patients aged 18 to 35 years were evaluated: 34 with diagnosis of TMD by the Research Diagnostic Criteria for Temporomandibular Disorders constituted the TMD group and 27 constituted the asymptomatic group. The subgroups were classified according to the presence of GJH by the Beighton score. Electromyographic recordings of the masseter and anterior temporal muscles were acquired bilaterally at mandibular rest and in maximal intercuspal position. Results: GJH was present in 64.71% of the individuals with TMD and in 40.74% of the asymptomatic individuals. The electrical activity was significantly higher in the right masseter (p = 0.0111), left masseter (p = 0.0007) and right temporal (p = 0.0046) in the patients with TMD than in the asymptomatic individuals. The activity of the left masseter muscle was significantly higher (p=0.0072) in the volunteers with TMD and GJH compared with in the individuals with TMD but without hypermobility. Also, the right temporal muscle showed higher activity in subjects with GJH and TMD compared with asymptomatic individuals without hypermobility (p=0.0248). Conclusions: The electrical activity was higher at mandibular rest in TMD and TMD/ GJH patients. This result suggests that these muscles need to be recruited for the joint stabilization due to the low ligamentar resistance and a possible proprioceptive deficit. This recruitment appears to occur asymmetric and variedly among all muscles involved in this stabilization, which could compensate for the low ligamentar competence and a possible proprioceptive deficit in individuals with GJH. Both TMD and GJH seem to have influenced the muscular activity

Valutazione strumentale delle malocclusioni di Classe II

Objectives In the present study, the authors investigated the possible etiological role of the masticatory muscles in the development of Angle class II malocclusion in hypodivergent and hyperdivergent patients. Materials and methods Ten patients with Angle class II malocclusion were examined, and each underwent surface electromyography, T-Scanning, and kinesiography. Results Compared with the hyperdivergent patients, those who were hypodivergent exhibited increased activation of all the muscles studied, especially the anterior temporalis and masseter, which presented a more anterior occlusal barycenter and higher-velocity opening and closing. Conclusion Structural and/or positional changes in the mandibles can be related to dysfunctional muscle activity. The muscle dysfunction can alter the growth pattern, especially in hypodivergent patients.

Site-to-site variation of muscle activity and sensitivity in the human anterior temporalis muscle: Implications for contingent stimulation

Objective. To evaluate variation of electromyographic (EMG) activity and sensitivity between different sites of anterior temporalis (AT) muscle. Materials and methods. Sixteen healthy subjects (eight men: 28.8 ± 5.2 year old and eight women: 29.1 ± 3.9) participated in one experimental session. EMG activity during masticatory muscle contraction was recorded from nine sites at the AT muscle in a 3 × 3 grid with 1 cm between. The subjects maintained steady 30% of maximal voluntary contraction (MVC) using visual feedback. The surface EMG electrode was moved sequentially between these nine test sites and the contractions were repeated. One site was tested four times to assess test–re-test variability. The sensory threshold to electrical stimulation and impedance was also measured at the same sites as the placement of EMG electrodes. Results. The 30% MVC force values did not differ between sites (p = 0.863) or within the same site (p = 0.995) due to the feedback. The EMG activity during 30% MVC was highest at the anterior–superior site (p < 0.05) with a marginal difference within the same site (p = 0.044). Impedance was higher at the posterior–superior, posterior–middle and posterior–inferior sites (p < 0.05). The sensory threshold was highest at the posterior–superior site (p < 0.05). Conclusions. These findings showed that electrodes close to the hairline have higher impedance and sensory thresholds and should be avoided. The anterior–superior site produces the highest EMG activity and lower sensory thresholds and can be recommended as the optimal site to place the electrode for contingent stimulation.

Electromyographic analysis of masseter and anterior temporalis muscle in sleep bruxers after occlusal splint wearing

Bruxism is widely defined as an anxiety response to environmental stress. Occlusal splints are frequently used in sleep bruxism, to protect teeth from damage resulting from the contraction force of mandibular muscles, or to reduce the orofacial pain by relaxing masticatory muscles. Surface electromyography (EMG) of the right and left masseter and temporalis muscles was performed in 15 women presenting sleep bruxism and temporomandibular disorders related to occupational stress, after nocturnal use of the occlusal splint. The EMG signals were recorded twice per patient: After a work shift (pre-splint) and after a night of sleep with the occlusal splint (post-splint) before a new workday. The parametric t-paired test was used to compare differences of the RMS amplitude between pre and post-splint records, for resting and maximal clenching effort. The level of significance for each comparison was set to p < 0.05. The results of the study supports the premise that the use of occlusal splint reduces EMG activity in the masseter and anterior temporalis muscles, in patients who presented with sleep bruxism related to occupational stress.

Surface electromyographic assessment of patients with long lasting temporomandibular joint disorder pain

The normalized electromyographic characteristics of masticatory muscles in patients with temporomandibular joint disorders (TMD) and healthy controls were compared. Thirty TMD patients (15 men, 15 women, mean age 23 years) with long lasting pain (more than 6 months), and 20 control subjects matched for sex and age were examined. All patients had arthrogenous TMD according to the Research Diagnostic Criteria for TMD (RDC/TMD). Surface electromyography of masseter and temporal muscles was performed during maximum teeth clenching either on cotton rolls or in intercuspal position. Standardized EMG indices and the median power frequency were obtained, and compared between the two groups and sexes using ANOVAs. During clenching, the TMD patients had larger asymmetry in their temporalis muscles, larger temporalis activity relative to masseter, and reduced mean power frequencies than the control subjects ( p < 0.05, ANOVA). In both groups, the mean power frequencies of the temporalis muscles were larger than those of the masseter muscles ( p < 0.001). No sex related differences, and no sex × group interactions were found. In conclusion, young adult patients with long lasting TMD have an increased and more asymmetric standardized activity of their temporalis anterior muscle, and reduced mean power frequencies, relative to healthy controls.

Muscle Response during Treatment of Class II Division 1 Malocclusion with Forsus Fatigue Resistant Device

To evaluate the muscle response in order to determine the mechanism of neuromuscular adaptations with Forsus Fatigue Resistant Device which has greater elasticity and flexibility; allows greater range of movement of mandible; is available in prefabricated assembly of springs, tubes and rods and is a simple, effective and reliable corrective appliance that benefits not only growing patients but also malocclusions that previously required extractions, headgears and surgery. Bilateral EMG activity from anterior temporalis and masseter muscles was monitored longitudinally on 10 young growing females with Class II Division 1 malocclusion to determine changes in postural, swallowing, and maximal voluntary clenching over an observation period of 6 months. There was a significant decrease in the muscle activity at one month after Forsus Fatigue Resistant Device insertion during swallowing of saliva and maximal voluntary clenching which gradually returned to pre treatment levels at the end of six months. This study suggests that Forsus Fatigue Resistant Device should be given for at least six months to allow for adequate neuromuscular adaptations to occur for long-term stability of the result.

Occlusal measurement method can affect SEMG activity during occlusion

Occlusal indicators are widely used in dental treatment to measure tooth contacts that occur during occlusion. However, the presence of an indicator may affect the mechanics of occlusion and lead to invalid tooth contact data. The objective of this study was to determine the effect of four indicators (Parkell, silk, T-Scan(®) sensor and paper) on surface electromyography (SEMG) activity during occlusion. Twenty-three subjects performed strong bites and maximum clenches onto the four indicators and natural dentition. Surface electromyography recordings of anterior temporalis and superficial masseter activity and the subjects' perception of each indicator were measured. SEMG activity with the T-Scan(®) sensor and paper was significantly different (higher masseter activity; P < 0·05) compared to that for natural dentition. The Parkell and silk gave no significant differences to natural dentition. Similarly, subjects perceived that T-Scan(®) sensor and paper had the greatest effect on occlusion and were the least comfortable (P < 0·05). Thus, the very plastic T-Scan(®) sensor and very thick articulating paper both affected SEMG activity during occlusion and, therefore, may not provide valid tooth contact information for dental treatment. In conclusion, occlusal indicators can change SEMG activity during occlusion which may affect the validity of the measurements they provide.

Silent Period of Masticatory Cycles in Dentate Subjects and Complete Denture Wearers

The purpose of this study was to assess, through electromyographic activity (EMG), the silent period (SP) of masseter and anterior temporal muscles in dentate subjects (DS) and complete denture wearers (CDW). The evaluations were performed at the initial and final period of the mastication for the DS group. For the CDW group, the evaluations were performed at the initial period of mastication, with old complete dentures worn for more than 10 years (OCDW) and at the final period of the mastication with new complete dentures (NCDW), 5 months after rehabilitation. Twenty-four asymptomatic subjects (12 DS, 12 CDW) answered a questionnaire based on the Research Diagnostic Criteria for temporomandibular disorders. The CDW group answered the questionnaire before and after new denture insertion and after 5 months of rehabilitation. The SP of the muscles was recorded through EMG at the initial and final periods of mastication using artificial food (Optocal). The operator monitored 35 chewing cycles performed to grind the artificial food and selected eight open-close-clench-chewing cycles for the record. The SP of the muscles analyzed with new complete dentures showed no statistical difference in comparison to the old dentures. There was a statistically significant difference in the SP between the CDW and DS groups for initial and final chewing. Lowered muscular capacity and ability reduced the SP of muscles after rehabilitation with NCDWs.

Influence of Pre-Orthodontic Trainer treatment on the perioral and masticatory muscles in patients with Class II division 1 malocclusion

The aim of this follow-up study was to evaluate the effects of Pre-Orthodontic Trainer (POT) appliance on the anterior temporal, mental, orbicularis oris, and masseter muscles through electromyography (EMG) evaluations in subjects with Class II division 1 malocclusion and incompetent lips. Twenty patients (mean age: 9.8 ± 2.2 years) with a Class II division 1 malocclusion were treated with POT (Myofunctional Research Co., Queensland, Australia). A group of 15 subjects (mean age: 9.2 ± 0.9 years) with untreated Class II division 1 malocclusions was used as a control. EMG recordings of treatment group were taken at the beginning and at the end of the POT therapy (mean treatment period: 7.43 ± 1.06 months). Follow-up records of the control group were taken after 8 months of the first records. Recordings were taken during different oral functions: clenching, sucking, and swallowing. Statistical analyses were undertaken with Wilcoxon and Mann-Whitney U-tests. During the POT treatment, activity of anterior temporal, mental, and masseter muscles was decreased and orbicularis oris activity was increased during clenching and these differences were found statistically significant when compared to control. Orbicularis oris activity during sucking was increased in the treatment group (P < 0.05). In the control group, significant changes were determined for anterior temporal (P < 0.05) and masseter (P < 0.01) muscle at clenching and orbicularis oris (P < 0.05) muscle at swallowing during observation period. Present findings indicated that treatment with POT appliance showed a positive influence on the masticatory and perioral musculature.

An electromyographic study to assess the minimal time duration for using the splint to raise the vertical dimension in patients with generalized attrition of teeth

To investigate the effect of restoration of lost vertical by centric stabilizing splint on electromyographic (EMG) activity of masseter and anterior temporalis muscles bilaterally in patients with generalized attrition of teeth. EMG activity of anterior temporalis and masseter muscle was recorded bilaterally for 10 patients whose vertical was restored with centric stabilizing splint. The recording was done at postural rest position and in maximum voluntary clenching for each subject before the start of treatment, immediately after placement of splint and at subsequent recall visits, with splint and without the splint. The EMG activity at postural rest position (PRP) and maximum voluntary clench (MVC) decreased till 1 month for both the muscles. In the third month, an increase in muscle activity toward normalization was noted at PRP, both with and without splint. At MVC in the third month, the muscle activity without splint decreased significantly as compared to pretreatment values for anterior temporalis and masseter, while with the splint an increase was seen beyond the pretreatment values. A definite response of anterior temporalis and masseter muscle was observed over a period of 3 months. This is suggestive that the reversible increase in vertical prior to irreversible intervention must be carried out for a minimum of 3 months to achieve neuromuscular deprogramming. This allows the muscle to get adapted to the new postural position and attain stability in occlusion following splint therapy.

Occlusal force, electromyographic activity of masticatory muscles and mandibular flexure of subjects with different facial types

ObjectiveThe aim of this study was to evaluate whether vertical facial patterns influence maximal occlusal force (MOF), masticatory muscle electromyographic (EMG) activity, and medial mandibular flexure (MMF).Material and MethodsSeventy-eight dentate subjects were divided into 3 groups by Ricketts's analysis: brachyfacial, mesofacial and dolychofacial. Maximum occlusal force in the molar region was bilaterally measured with a force transducer. The electromyographic activities of the masseter and anterior temporal muscles were recorded during maximal voluntary clenching. Medial mandibular flexure was calculated by subtracting the intermolar distance of maximum opening or protrusion from the distance in the rest position. The data were analyzed using ANOVA followed by Tukey's HSD test. The significance level was set at 5%.ResultsData on maximum occlusal force showed that shorter faces had higher occlusal forces (P<0.0001). Brachyfacial subjects presented higher levels of masseter electromyographic activity and medial mandibular flexure, followed by the mesofacial and dolychofacial groups. Additionally, dolychofacial subjects showed significantly lower electromyographic temporalis activities (P<0.05).ConclusionWithin the limitations of the study, it may be concluded that maximum occlusal force, masticatory muscle activity and medial mandibular flexure were influenced by the vertical facial pattern.