The use of a custom-made mouthguard stabilizes the electromyographic activity of the masticatory muscles among Karate-Do athletes.

AIMS: To analyze and compare the electromyographic activity of the temporal (anterior portion) and masseter muscles among Karate-Do athletes before and after training, with and without the use of a mouthguard. METHODS: Twenty athletes (14 males and 6 females) with a mean age of 23.7 ± 7.5 years participated. They had surface electromyography recordings taken of their bilateral temporal and masseter muscles before and after training under the following conditions: no mouthguard, with a ready-made mouthguard, and with a custom-made mouthguard. Activity was examined at mandibular rest, while clenching, and at maximum voluntary contraction. The data were normalized using the mean maximum voluntary contraction. RESULTS: The right (p = 0.005) and left (p = 0.015) temporal muscles showed significantly lower electromyographic activity with a custom-made mouthguard compared with no mouthguard after training while clenching. The electromyographic activity of the temporal and masseter muscles did not show significant differences when tested at mandibular rest and while clenching before or after training with a custom-made mouthguard (p > 0.05). CONCLUSION: The use of a custom-made mouthguard preserved participants' electromyographic profiles before and after training; thus, they allow for stable muscle activity during the training of Karate-Do athletes.

Orthodontic intervention combined with myofunctional therapy increases electromyographic activity of masticatory muscles in patients with skeletal unilateral posterior crossbite.

OBJECTIVE: The aim of this study was to evaluate the electromyographic activity of both the temporalis and masseter muscles and the mastication type of patients with skeletal unilateral posterior crossbite before and after orthodontic treatment and speech therapy. METHODS: A total of 14 patients with skeletal unilateral posterior crossbite (eight females and six males), between 6-13 years of age, underwent electromyographic evaluation of their masseter and temporalis muscles in mandibular rest, habitual mastication and isometry. The subjects were assessed with regard to mastication type before and after orthodontic treatment and speech therapy. The data obtained during mandibular rest and habitual mastication were normalized in terms of the mean values of isometry. The Student's t-test was used for paired samples to compare the mean values of electromyographic activity (p < 0.05). RESULTS: The masseters during habitual mastication presented higher electromyographic activity after both treatments (p = 0.0458). There was no significant difference between the contralateral masseters in terms of mandibular rest or habitual mastication before or after either treatment (p > 0.05). During habitual mastication, after the treatments, the temporalis muscle on the malocclusion side showed higher electromyographic activity than the contralateral side (p = 0.0263). Prior to therapy, all of the patients exhibited chronic unilateral mastication (n = 14) and 13 patients exhibited bilateral mastication after treatment. CONCLUSIONS: Orthodontic intervention combined with myofunctional therapy in patients with skeletal unilateral posterior crossbite provided an increase in the electromyographic activity of the masseter and temporalis muscles during mandibular rest and habitual mastication, with predominantly bilateral mastication.

Características da função mastigatória em indivíduos com mordidacruzada posterior unilateral / Masticatory function characteristics in individuals with unilateralposterior crossbite

Objetivo: Analisar as características da função mastigatória em indivíduos com mordida cruzada posterior unilateral. Material e métodos: A amostra foi dividida em 2 grupos: grupo 1, composto por 12 indivíduos com mordida cruzada posterior unilateral; e grupo 2, com 11 indivíduos com oclusão normal. Os participantes do estudo foram examinados por ortodontista e fonoaudióloga para identificar as características clínicas da oclusão bem como da função mastigatória e de hábitos de sucção e deglutição. Resultados: No Grupo 1, 5 (41,67%) pacientes apresentaram maloclusão Classe I de Angle; 6 (50%), maloclusão Classe II; e 1 (8,33%), Classe III. Não houve diferença estatisticamente significante entre os grupos para as variáveis uso de chupeta e/ou hábitos bucais, posição de língua durante a deglutição e trituração total do bolo alimentar (p ≥ 0,05). Houve diferença estatisticamente significante entre os grupos para a dificuldade de mastigar alimentos fibrosos (p = 0,0033). Conclusão: A mordida cruzada posterior unilateral foi observada em pacientes com os três tipos de classificação oclusal sagital. Esteve associada à dificuldade de mastigar alimentos fibrosos, não alterando, entretanto, o resultado final da trituração do bolo alimentar.

Objective: To analyze masticatory function characteristics in subjects with unilateral posterior crossbite. Materials and methods: The sample was divided in two groups: group 1, comprised of 12 subjects with unilateral posterior crossbite; and group 2, with 11 subjects with normal occlusion. They were examined by orthodontist and speech therapist to identify clinical characteristics of occlusion, masticatory function, and sucking and swallowing habits. Results: In Group 1 it was observed that 5 (41.67%) patients had Angle Class I malocclusion, 6 (50%), Class II malocclusion, and 1 (8.33%), Class III. There was no statistically significant difference between groups for the following variables: use of pacifier and/or oral habits, tongue position during swallowing and total crushing the bolus (p ≥ 0.05). There was statistically significant difference between groups for difficulty in chewing fibrous foods (p = 0.0033). Conclusion: The unilateral posterior crossbite was observed in patients with three types of sagittal occlusal classification. It was associated with difficulty in chewing fibrous foods, not changing, however, the final result of crushing the bolus.

Electromyographic activity of masseter and temporal muscles with different facial types.

OBJECTIVES: To compare the electromyographic (EMG) activity of the masseter and anterior portion of temporal muscles in different vertical facial types. MATERIALS AND METHODS: Clinical examination, cephalometric analysis, and electromyographic examination were performed in 44 volunteers ranging from 18 to 35 years old. The volunteers were classified on the basis of their vertical facial characteristics into three groups-brachyfacial, mesofacial, and dolicofacial-by the grouping analysis. The EMG records were obtained with three repetitions during mandibular rest, maximum voluntary contraction in intercuspidation, and simultaneous bilateral isotonic contraction. The Kolmogorov-Smirnov and Levene tests were applied to verify the normality and homogeneity of variance. Analysis of variance and the Kruskal-Wallis test identified statistical differences among groups that did not present normality and homogeneity of distribution, respectively. Significance for all statistical tests was set at P < .05. RESULTS: At rest, only the right temporal and masseter muscles presented statistically significant differences among the groups. The differences were observed between groups 1 and 2 (P = .02) and 1 and 3 (P = .038) for the right temporal muscle, and between groups 1 and 2 (P = .029) for the right masseter muscle. Generally, group 1 presented the lowest EMG values for the four muscles evaluated during rest. For isotonic evaluation, none of the groups of muscles presented statistically significant differences. CONCLUSION: Different vertical facial types do not determine distinct patterns of EMG activity for the masseter and anterior portion of temporal muscles during rest and bilateral mastication.

Electromyographic activity evaluation and comparison of the orbicularis oris (lower fascicle) and mentalis muscles in predominantly nose- or mouth-breathing subjects.

INTRODUCTION: The objective of this study was to evaluate and compare the electromyographic (EMG) activity of the orbicularis oris--lower fascicle (LOO) muscle and the mentalis muscle (MT)--in predominantly nose-breathing (PNB) and mouth-breathing (PMB) subjects. METHODS: Thirty-four subjects, 22 PNB and 12 PMB, with Class II Division 1 malocclusions were evaluated in 2001 (T1) and again in 2004 (T2), 2 years 5 months later. The age ranges of the sample were 11 years to 14 years 11 months at T1, and 13 years 4 months to 16 years 6 months at T2. EMG activity was recorded with bipolar surface electrodes at rest and during 12 movements; data were processed and normalized by the EMG highest value. The Student t test and the Mann-Whitney nonparametric test were used to compare the mean values and the variables between the observation times. RESULTS: Greater EMG activity of the MT was observed in the PMB group at rest and swallowing at T1 and T2. At T2, increased EMG activity of the LOO at blowing and pronunciation of the phoneme \b\ was observed as well as a greater increment of EMG activity of this muscle at blowing, pronunciation of the phoneme \m\, and chewing in the PMB group. In addition, greater EMG activity of the MT at chewing in the PMB group was observed at T2. CONCLUSIONS: These results suggest that mouth breathing influences EMG activity of the LOO and MT muscles.

Electromyographic analysis of the upper lip in nose and mouth breathers

The purpose of this research was to compare the electromyographic (EMG) activity of the superior belly of orbicularis oris muscle between individuals with Class II Division 1 malocclusion, nose breathers (Group 1) and mouth breathers (Group 2), having as a comparative parameter a control group of individuals with clinically normal occlusion (Group 3). The EMG recordings were obtained in resting position and in 16 movements. A statistically significant difference between Groups 1 and 2 was observed during puffing out with flaccid cheeks, dispelling of the lips’ angle and saliva deglutition; between Groups 1 and 3 during puffing out with flaccid cheeks, posterior right and left clenching and saliva deglutition; between 2 and 3 during posterior right and left clenching. According to the normalized data the malocclusion groups (Groups 1 and 2) have a similar muscle behavior but when they are compared with the normal occlusion group there was a statistically significant difference between them. It can be concluded that, for this sample, the breathing mode did not influence the muscular behavior of the subjects with Class II division 1 malocclusion and that subjects with normal occlusion have more competent lips than the ones with Class II division 1 malocclusion.