Evaluation of the bioelectrical activity of the masticatory muscles in patients with narrowed maxillary transverse dimension compared to the occlusal norm

OBJECTIVE

The aim of the study was to determine how the electrical activity of the temporalis, masseter and sternocleidomastoid muscles differs in children with reduced transverse jaw dimension compared to children with normal occlusion.

DESIGN

It was a experimental study. Thirty-seven patients were included in the study. 18 in the study group received orthodontic treatment with removable appliances and 19 subjects were classified as normal occlusion subjects in the control group. A panoramic X-ray and digital intraoral scan were taken, followed by an surface electromyography of three muscle pairs (temporalis muscles, masseter muscles, sternocleidomastoid muscles) in resting position, while clenching and clenching on cotton rollers.

RESULTS

There was significantly greater activity in the experimental group than in the control group comparing muscles: temporalis muscles and masseter muscles in the resting position. Additionally, significantly greater activity of muscles in the control group was found during clenching. However, the asymmetry index of muscles indicates that there is significantly greater asymmetry of muscles activity in the experimental group. Compared to children with normal occlusion, children with a narrowed transverse dimension of the jaw have statistically significant differences in the bioelectrical activity of the temporalis, masseter and sternocleidomastoid muscles, as well as greater asymmetry in the bioelectrical voltage of the masseter muscles.

CONCLUSIONS

Patients with reduced transverse dimension of the jaw are characterized by increased resting activity of the masticatory muscles and reduced functional activity of the masticatory muscles. These patients have increased asymmetry in the bioelectrical tension of the masticatory muscles.

Hypoglossal nerve trunk stimulation: electromyography findings during drug-induced sleep endoscopy: a case report

BACKGROUND

Literature has demonstrated hypoglossal nerve stimulation to be a safe and effective treatment for patients with obstructive sleep apnea nonadherent to positive airway pressure therapy. However, the recommended criteria for patient selection are still unable to identify all the unresponsive patients, highlighting the need for improved understanding about hypoglossal nerve stimulation for obstructive sleep apnea.

CASE PRESENTATION

A 48-year-old Caucasian male patient with obstructive sleep apnea had been successfully treated with electrical stimulation of the hypoglossal nerve trunk, documented by level 1 polysomnography data. However, due to snoring complaints, he underwent postoperation drug-induced sleep endoscopy for evaluation of electrode activation during upper airway collapse, aiming to improve electrostimulation parameters. Concurrent surface electromyography of the suprahyoid muscles and masseter was obtained. Activation of electrodes 2, 3, and 6 promoted upper airway opening most strongly at the velopharynx and tongue base during drug-induced sleep endoscopy. The same channels also significantly increased the electrical activity on suprahyoid muscles bilaterally, but predominantly on the stimulated side (right). The masseters also presented a considerable asymmetry in electrical potential on the right side (> 55%).

CONCLUSION

Beyond the genioglossus muscle, our findings demonstrate recruitment of other muscles during hypoglossal nerve stimulation, which may be attributed to the electrical stimulation of the nerve trunk. This data provides new insights on how stimulation of the hypoglossal nerve trunk may contribute to obstructive sleep apnea treatment.

Interference of dentofacial deformities in the acoustic characteristics of speech sounds

ABSTRACT Purpose: to verify speech characteristics regarding the production of fricative sounds in people with dentofacial deformities (DFD), through acoustic analysis, evaluating possible interferences of the variation of the osseous bases in the articulation of speech. Methods: fifteen adults of both genders, aged between 17 and 42, participated in the study. They were distributed in three groups: GII (n = 5) Skeletal Class II, GIII (n = 5) Skeletal Class III, and CG (n = 5) without DFD. All of them had their voices recorded, with key words containing the fricative sounds of Brazilian Portuguese (BP), and acoustically analyzed; the parameters: duration, intensity, and formants F1, F2. The Mann-Whitney test was used to compare the groups. Results: there were differences (p <0.05) when comparing GII and GIII with CG. For the variable duration GIII obtained higher value in the fricative sound /z/ (r = 0.016, p <0.05). The variable intensity was higher for GII in /z/ (r = 0.028, p <0.05), and higher for GIII in /f/ (r = 0.028, p <0.05), /v/ (r = 0.028, p<0.05) and /ʃ/ (r = 0.036, p <0.05). For the variable F1, GII obtained a higher value for the syllable /za/ (r = 0.047, p <0.05). In the variable F2, GII obtained the lowest value in the syllable /ʒa/ (r = 0.047, p <0.05). Conclusion: the disharmony of the maxillomandibular osseous bases results in interference in speech acoustic characteristics regarding fricative sounds.

Relationship between electrical activity of the temporal and masseter muscles, bite force, and morphological facial index

PURPOSE

To analyze possible correlations between the electrical activity of masseter and temporal muscles, Bite Force (BF), and Morphological Facial Indices (MFI).

METHODS

The study involved 43 young adults, both genders, 18 to 37 years old. The individuals were submitted to: face measurement to calculate MFI; Masseter and Temporal Surface Electromyography (sEMG) and BF measurements on right and left premolars and incisors. The following electromyographic tests were conducted: at rest position; Maximal Voluntary Isometrical Contraction (MVIC) and usual chewing of raisins. Statistical analysis was conducted using the coefficient of Spearman correlation with significance level of 5%.

RESULTS

The values at rest in the temporal muscles were significantly higher than those in the masseter muscles. A meaningful correlation was found between MFI and sEMG in the MVIC test for the Left Temporal (rs=36, p=0.017). A significant correlation was observed between FMI and sEMG during BF in incisors for temporal muscles and the Right Masseter. During the force tests, it was possible to observe a meaningful correlation between BF in right premolars and the sEMG of the Left Temporal and Masseters.

CONCLUSION

No correlation was found between the sEMG of temporal and masseter muscles, BF, and FMI in adult individuals based on the tests performed. The SEMG of temporal and masseter muscles seems to be associated only with BF. As a datum of habitual postural characteristic, the electrical activity of temporal muscles is higher than the activity of masseters, also regardless of MFI.