Electromyography of the masticatory muscles during chewing in different head and neck postures - A pilot study

The linear intra-articular motions of the temporomandibular joint in individuals with severe forward head posture: A cross-sectional study

BACKGROUND

The cervical vertebrae and the temporomandibular joint (TMJ) may be linked through their common muscles.

OBJECTIVES

The aim of the present study was to compare the linear intra-articular motions of the TMJ between individuals with the normal craniocervical posture (CCP) and severe forward head posture (FHP).

DESIGN

Cross-sectional study.

METHODS

Volunteers (N = 38) were equally assigned to either the severe FHP group or the normal CCP group according to their craniovertebral angle (CVA). The CVA angles greater than 49° were considered as the normal CCP while angles between 44 and 40° were regarded as the severe FHP. The TMJ was imaged at the closed, median, and maximum open positions of the mouth using an ultrasound machine with a 7.5 MHz linear transducer in the sitting position. The best-fitting curve in the contour registration method was employed to measure displacement of the mandibular condyle on the transverse and vertical axes.

RESULTS

The forward displacement of the mandibular condyle in the severe FHP group was significantly (p-value = 0.037) reduced compared to the normal CCP group at maximum open position of the mouth, while no significant difference was revealed at closed (p-value = 0.937) or median open (p-value = 0.699) positions. The perpendicular displacement of the mandibular condyle exhibited no significant (p-value>0.107) difference between groups at any mouth position.

DISCUSSION

The current study demonstrated, for the first time, that severe FHP may impact the intra-articular motion of the TMJ. This study presumed that individuals with severe FHP may encounter a force imbalance in the anterior-posterior direction.

Synchronous Muscle Synergy Evaluation of Jaw Muscle Activities during Chewing at Different Speeds, a Preliminary Study

Human mastication is a complex and rhythmic biomechanical process regulated by the central nervous system (CNS). Muscle synergies are a group of motor primitives that the CNS may combine to simplify motor control in human movement. This study aimed to apply the non-negative matrix factorization approach to examine the coordination of the masticatory muscles on both sides during chewing. Ten healthy individuals were asked to chew gum at different speeds while their muscle activity was measured using surface electromyography of the right and left masseter and temporalis muscles. Regardless of the chewing speed, two main muscle synergies explained most of the muscle activity variation, accounting for over 98% of the changes in muscle patterns (variance accounted for >98%). The first synergy contained the chewing side masseter muscle information, and the second synergy provided information on bilateral temporalis muscles during the jaw closing. Furthermore, there was robust consistency and high degrees of similarity among the sets of muscle synergy information across different rate conditions and participants. These novel findings in healthy participants supported the hypothesis that all participants in various chewing speed conditions apply the same motor control strategies for chewing. Furthermore, these outcomes can be utilized to design rehabilitation approaches such as biofeedback therapy for mastication disorders.

Food consumption and masticatory performance of normal weight, overweight and obese children aged 7 to 12 years old

Childhood obesity is a significant public health problem. Studies show that obese children are more likely to become obese adults. In an attempt to ascertain the factors associated with childhood obesity, research has shown that this condition is associated with changes in food consumption and masticatory performance. The aim of this study was thus to evaluate food consumption and masticatory performance in normal weight, overweight and obese children aged 7 - 12 years. A cross-sectional study was carried out with 92 children aged 7 - 12 years, of both sexes, from a public school in a Brazilian municipality. The children were divided into the following groups: normal weight (n = 48), overweight (n = 26) and obese (n = 18). Anthropometric parameters, food consumption, food consistency preference, and masticatory performance were evaluated. Pearson's chi-square test was used to compare categorical variables. To compare numerical variables, the one-way ANOVA test was applied. For variables not conforming to a normal distribution, the Kruskal-Wallis test was used. The level of statistical significance was set at p ≤ 0.05. Our results show that the children with obesity consumed fewer fresh foods (median = 3, IQI = 4.00-2.00, p = 0.026), consumed more ultra-processed foods (median = 4, IQI = 4.00-2.00, p = 0.011), performed fewer mastication sequences (median = 2, IQI = 3.00-2.00, p = 0.007), and ate faster (median = 58.50, IQI = 69.00-48.00, p = 0.026) compared to children of normal weight. We conclude that children with obesity exhibit differences in food consumption and masticatory performance compared to children of normal weight.

The Masticatory Structure and Function in Children with Cerebral Palsy—A Pilot Study

(1) Background: Muscle tension around the head and neck influences orofacial functions. The data exist concerning head posture during increased salivation; however, little is known about muscle tightness during this process. This study aims to investigate whether or not any muscles are related to problems with eating, such as drooling in individuals with cerebral palsy; (2) Methods: Nineteen patients between the ages of 1 and 14 were examined prior to the physiotherapy intervention. This intervention lasted three months and consisted of: relaxing muscles via the strain-counterstrain technique, functional exercises based on the NeuroDevelopmental Treatment-Bobath method, and functional exercises for eating; (3) Results: the tone of rectus capitis posterior minor muscle on the left side (p = 0.027) and temporalis muscle on the right side (p = 0.048) before the therapy, and scalene muscle on the right side after the therapy (p = 0.024) were correlated with drooling behavior and were considered statistically significant. Gross motor function was not considered statistically significant with the occurrence of drooling behavior (p ≤ 0.05). Following the therapeutic intervention, the frequency of drooling during feeding decreased from 63.16% to 38.89% of the total sample of examined patients; (4) Conclusions: The tightness of the muscles in the head area can cause drooling during feeding.

Electromyographic evaluation of masseter and temporalis muscle activity after periodontal surgery: A prospective clinical trial

Objectives

Following periodontal treatment, tooth supporting structures are restored to functionality and hence improve muscle activity. In this study, we aimed to investigate the influence of periodontal disease on muscle activity by electromyography and the subjective perception of periodontal therapy through the Oral Impact on Daily Performance (OIDP) questionnaire.

Methods

Sixty subjects with moderate to severe periodontitis were included. Periodontal condition was re-evaluated 4-6 weeks after non-surgical periodontal therapy (NSPT). Subjects with persistent probing pocket depths ≥5 mm were designated for flap surgery. All clinical parameters were recorded at baseline, 3 months and 6 months after surgery. The activities of the masseter and temporalis muscles were measured by electromyography and OIDP scores were recorded at baseline and 3 months.

Results

The mean plaque index scores, probing pocket depths, and clinical attachment levels were reduced from baseline to 3 months. Mean EMG scores were compared at baseline and 3 months post-surgery. The mean OIDP total score prior to and after periodontal therapy was significantly different.

Conclusion

There was a statistically significant correlation between clinical parameters, muscle activity and a patient's subjective perception. Therefore, it can be concluded that successful periodontal flap surgery led to improvements in masticatory efficiency and subjective perception, as determined by the OIDP questionnaire.

Alterations in kinematics of temporomandibular joint associated with chronic neck pain

BACKGROUND

Temporomandibular disorder (TMD) is an umbrella term for pain and dysfunction of the temporomandibular joint (TMJ) and its associated structures. Patients with TMD show changes in TMJ kinematics and masticatory muscle activation. TMD is commonly comorbid with non-specific chronic neck pain (NCNP), which may be one of the risk factors for TMD.

OBJECTIVES

This study aimed to investigate whether patients with NCNP have altered TMJ kinematics and masticatory muscle activity.

METHODS

This was a cross-sectional exploratory study including 19 healthy participants and 20 patients with NCNP but without TMD symptoms. TMJ kinematics was measured during mouth opening and closing, jaw protrusion and jaw lateral deviation. Surface electromyography was used to record the muscle activity of the anterior temporalis, masseter, sternocleidomastoid and upper trapezius while clenching. Furthermore, cervical posture, cervical range of motion (ROM) and pressure-pain threshold of the neck and masticatory muscles were measured.

RESULTS

Compared with the healthy group, the NCNP group showed significantly reduced upper cervical rotation ROM (p = .041) and increased condylar path length (p = .02), condylar translation (opening p = .034, closing p = .011) and mechanical pain sensitivity of the upper trapezius (p = .018). Increased condylar translation was significantly correlated with reduced upper cervical mobility and poor cervical posture (r = -0.322 to -0.397; p = .012-.046).

CONCLUSION

Increased condylar translation and path length in patients with NCNP may indicate poor control of TMJ articular movement, which may result from neck pain or may be a compensation for limited neck mobility. Evaluation of excessive TMJ translation may be considered in patients with NCNP.

Muscle Activity in Pre-Treatment and Post-Treatment Oral Submucous Fibrosis Patients: Electromyography Study

BACKGROUND

Oral submucous fibrosis (OSMF) is a premalignant condition of insidious onset which affects the oral mucosa, pharynx, and esophagus. The muscles of mastication are known to be affected resulting in limited mouth opening. Electromyography (EMG) is a sophisticated method of measuring and evaluating muscle activity. Previously, EMG was primarily utilized in medical sciences, but it is currently being used extensively in both the medical and dentistry fields.

OBJECTIVES

The aim of the study is to evaluate the electromyographic activity of masseter muscle in OSMF patients before and after treatment and to compare with healthy controls.

MATERIALS AND METHODS

This prospective case-control clinical study comprised 180 OSMF patients who were divided into four groups and 45 healthy individuals served as the control group. The OSMF individuals were injected with hyaluronidase 1,500 IU mixed in 1.5 ml of dexamethasone and 0.5 ml of lignocaine HCL intralesionally twice a week for one month along with a basic physiotherapy regimen consisting of mouth exercises two times daily. The control subjects were given placebo capsules. The treatment was carried out for a month and the electromyographic masseter muscle activity was evaluated among the OSMF patients and control group before and after treatment.

RESULTS

The results revealed that the electromyographic activity of master muscles in OSMF patients showed increased activity when compared with healthy controls. Patients with OSMF showed decreased muscle activity after treatment.

CONCLUSION

When compared with healthy controls, OSMF patients had higher electromyographic activity of the masseter muscles and the muscle activity was decreased following treatment. In OSMF patients, EMG may help in determining the involvement of the mastication and facial expression muscles. It can also be used as a diagnostic tool to assess the treatment outcome of muscle activity in OSMF patients.

Functional interaction of chewing muscles in children with dentoalveolar system anomalies

Relevance. The focus of modern dental treatment not only on the elimination of aesthetic, but also functional disorders requires an understanding of the functional conjugation of the chewing muscles, the possibility of interprognosis of parameters. Objective. Assess the functional relationship between the tone of the chewing muscles proper and the bioelectric activity of the temporal and sublingual muscle groups in children with anomalies of the dentoalveolar system. Materials and Methods. The study involved 36 patients of Childrens Clinical Dental Clinic No. 2 of Voronezh, aged 6 to 12 years, who had not previously received orthodontic treatment and had distal occlusion anomalies. Evaluation of the bioelectric activity of temporal and sublingual muscles was carried out using surface electromyography on the Electromyograph Dental apparatus (Taganrog, Russia), the Chewing General sample. Evaluation of the tone of the chewing muscles proper was carried out using the Mioton-3C device in a state of physiological rest of the lower jaw. Statistical processing was carried out using Microsoft Excel, version 7.0 and the statistical programs SPSS Statistics 21 and STATISTICA 7. Results and Discussion. Correlation analysis revealed the presence of 4 weak positive, 2 weak negative, 14 moderate positive, 3 moderate negative, and 1 noticeable positive correlation between the tone of the right chewing muscle proper and the parameters of the bioelectric activity of the right and left temporal and sublingual muscles. Correlation analysis revealed the presence of 5 weak positive, 7 weak negative, 9 moderate negative correlations between the tone of the left chewing muscle proper and the parameters of bioelectric activity of the right and left temporal and sublingual muscles. Conclusion. A greater effect of the tone of the right chewing muscle on the bioelectric activity of temporal and sublingual muscles was found compared to the tone of the left chewing muscle itself. 27 equations have been derived that can be used as predictive models for calculating the tone of right and left chewing muscles proper depending on the indicators of bioelectric activity of temporal and sublingual muscles.

Head Posture and Postural Balance in Community-Dwelling Older Adults Who Use Dentures

Background and objectives: Tooth loss and consequent denture use and impaired posture and postural balance are more prevalent in older adults than in the young ones. The aim of this cross-sectional study was to identify the association between denture use, head posture, postural balance, and neck muscle strength (NMS). Materials and methods: We included 107 participants (56 in the non-denture use group and 51 in the denture use group) and measured their NMS, forward head posture, and postural balance. Forward head posture was measured using the craniocervical angle (CRA). Postural balance was assessed using a timed up-and-go test (TUG) and postural sway. An independent t-test was used to analyze the differences between the groups; Pearson correlation analysis was used to analyze the correlation of period of denture use, head posture, and postural balance. Results: We found that the denture use group had lower NMS, smaller CRA, longer TUG, and longer postural sway length than the non-denture use group. Duration of denture use was significantly correlated with TUG. Conclusions: Our findings reveal that denture use does not help with NMS, forward head maintain NMS, head posture, and postural balance in older adults.