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

Assessment of neuromuscular fatigue through frequency analysis of the electromyographic signal of control participants and those with temporomandibular dysfunction treated with resilient or hard occlusal devices

STATEMENT OF PROBLEM

Muscle hyperactivity that leads to neuromuscular fatigue can be evaluated by electromyography. Whether treatment with occlusal devices can restore neuromuscular balance to patients with temporomandibular disorders (TMDs) is unclear.

PURPOSE

The purpose of this clinical study was to evaluate neuromuscular fatigue by analyzing the frequency of the electromyographic signal of the masseter and anterior temporalis muscles on both sides in healthy participants and those with TMD treated with a resilient or hard occlusal device.

MATERIAL AND METHODS

One hundred asymptomatic participants and 30 with TMD were divided into 2 groups: treated with a hard device or treated with a resilient device. All underwent electromyographic examination before and after treatment with the occlusal devices.

RESULTS

In both groups, the results showed statistically significant differences (P<.01) when the fatigue rate before and after treatment with an occlusal device was compared.

CONCLUSIONS

Treatment with both types of occlusal device was efficient in reducing the rate of neuromuscular fatigue in patients with TMDs.

Predictors of the masticatory muscle activity during chewing in patients with myogenous temporomandibular disorder

OBJECTIVES

The aim of the study was to identify predictors of the masticatory muscle activity during chewing (MMA) of the masseter and temporalis anterior (TA) muscles in patients with unilateral myogenous temporomandibular disorder (mTMD).

MATERIALS AND METHODS

This observational and cross-sectional study included 109 patients diagnosed with unilateral mTMD. Surface electromyography was used to separately evaluate the MMA of the masseter and TA on the affected and unaffected sides. Also, pain intensity (with a visual analog scale), pressure pain threshold (with an algometer), active pain-free maximum mouth opening and temporomandibular joint lateral movements (with a ruler), cervical range of motions (with a goniometer), and TMD severity (with a Fonseca Anamnestic Index) were assessed. Various statistical methods were used to predict the MMA of the masseter and TA, including standard, forward, and best subsets multiple regression models.

RESULTS

While there were significant correlations between the MMA of the masseter and TA and pain intensity, pressure pain threshold values, and TMD severity, they were not found with other variables. These parameters were also predictive factors for MMA of both muscles (p < 0.05).

CONCLUSIONS

According to the present study, pain intensity, muscle and joint tenderness, and the severity of the disorder are predictive factors for MMA of the masseter and TA muscles in patients with mTMD. It is recommended that these parameters be considered when establishing clinical evaluation and treatment programs focusing on MMA in patients with mTMD.

CLINICAL RELEVANCE

The pain intensity, masticatory muscles and TMJ tenderness, and disorder severity are predictors for MMA of the masseter and TA in patients with mTMD. Pain intensity has the most significant importance.

Repeatability of Teethan® indexes analysis of the masseter and anterior temporalis muscles during maximum clenching: a pilot study

OBJECTIVES

The aim of this study is to assess the repeatability of a surface electromyographic (EMG) device (Teethan®, Teethan S.p.A., Milan, Italy), designed for the analysis of the masseter and anterior temporalis muscles.

MATERIALS AND METHODS

Tests were performed on a sample of 30 healthy fully dentate TMD-free individuals randomly selected. Each test consisted of two distinct recordings performed at 5-min intervals: (i) the patient is asked to clench with maximum voluntary contraction (MVC), with two cotton rolls interposed between the dental arches; (ii) the patient is asked to repeat the same clenching activity without the cotton rolls. The outcomes of the study were the EMG indices conceptualized by the manufacturing company, based on the differences between the two test conditions (i.e., clenching on cotton rolls and on dentition). Pairwise correlation analysis and ANOVA test were performed to assess the strength of correlation and the significance of differences between the results of the three trials.

RESULTS

Thirty TMD-free healthy individuals (20 females and 10 males; mean age 44 years, range 16-60 years) took part in the study. ANOVA test did not show any statistically significant difference between the three trials. The Global Index, which is the mean of the other EMG indices, showed the highest correlation values between the three trials, while some other indices showed a weak-to-medium correlation level. One out of five participants showed a coefficient of variation higher than 10%.

CONCLUSIONS

The statistical analysis showed that the indices provided by the device are quite repeatable. However, this does not necessarily imply a specific clinical application of the device, which was here used in fully controlled experimental conditions.

CLINICAL RELEVANCE

The clinical usefulness of the applied protocol remains questionable. Further studies should test the repeatability of EMG findings gathered with this device under various circumstances, in a more heterogeneous population.

Myofunctional orofacial examination tests: a literature review

INTRODUCTION

Myofunctional orofacial examination (MOE) is an important tool for the assessment of the stomatognathic system and orofacial functions, and the early diagnosis of orofacial myofunctional disorders. Therefore, the purpose of the study is to scan the literature and determine the most preferred test for myofunctional orofacial examination.

MATERIALS AND METHODS

A literature review was conducted to collect information. Pubmed and ScienceDirect database was explored by using keywords gained by MeSH (Medical Subject Headings).

RESULTS

Fifty-six studies were retrived from the search and all of the studies were screened and evaluated regarding the subject, aim, conclusions and the orofacial myofunctional examination test they used. It has been observed that traditional evaluation and inspection methods have been replaced by newer and methodological approaches in recent years.

CONCLUSIONS

Although the few tests used differ, 'Orofacial Examination Test With Scores' (OMES) was found to be the most preferred myofunctional orofacial evaluation method from ENT to cardiology.

Short-term effect of orthodontic clear aligners on muscular activity and occlusal contacts: A cohort study

INTRODUCTION

The simultaneous presence of maxillary and mandibular clear aligners alters the vertical dimension and the quantity and quality of occlusal contacts. Few data in the literature explain how this occurs and the effects on neuromuscular coordination. This study aimed to evaluate occlusal contacts and muscular balance during treatment with clear aligners over a short follow-up time.

METHODS

Twenty-six female adult patients were enrolled in this study. The center of occlusal force (COF) was evaluated using a T-Scan II device, whereas muscular symmetry and balance were determined through surface electromyography using a standardized protocol that reduces anthropometric and electrode variations. Both evaluations were performed in centric occlusion and with aligners worn before treatment, after 3 months, and after 6 months.

RESULTS

A statistically significant variation in COF position was reported in the sagittal plane but not in the transverse plane. The shift in the COF position was followed by a change in muscular balance evaluated through surface electromyography.

CONCLUSIONS

Treatment with clear aligners resulted in an anterior shift of the COF when biting in centric occlusion and a posterior shift when the aligners were worn in healthy female patients after 6 months of observation. This change in occlusal contact was followed by an improvement in muscular function symmetry in the short term when aligners were worn, compared with the centric occlusion during treatment.

Surface electromyography in the assessment of masticatory muscle activity in patients with pain-related temporomandibular disorders: a systematic review

Background

Temporomandibular disorders (TMD) are a set of painful conditions affecting the orofacial region that are prevalent and constitute the most frequent type of non-dental pain complaint in the maxillofacial area. Pain-related TMD (TMD-P) is characterized by ongoing pain in the masticatory muscles, the temporomandibular joint, or surrounding structures. Due to the multiple factors that contribute to the development of this condition, it can be challenging to accurately diagnose. One of the useful method for assessing patients with TMD-P is surface electromyography (sEMG). The aim of this systematic review was to provide a comprehensive overview of the current scientific literature on the evaluation of masticatory muscle activity (MMA) in individuals diagnosed with TMD-P, through the utilization of sEMG.

Methods

To gather relevant information, electronic databases such as PubMed, Web of Science, Scopus, and Embase were searched using specific keywords including: "pain" AND ("temporomandibular disorder*" OR "temporomandibular dysfunction*") AND "surface electromyography" AND "masticatory muscle activity." The inclusion criteria were studies assessing MMA in patients with TMD-P using sEMG. The Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies was utilized to evaluate the quality of the studies that were included in the review.

Results

The search strategy identified 450 potential articles. Fourteen papers met the inclusion criteria. Global quality rating for significant part of the articles was weak. Most studies showed greater sEMG activity of the masseter (MM) and temporal anterior (TA) muscles at rest in TMD-P subjects than in the asymptomatic controls, while the MM and TA muscles were less active in the pain-related TMD group compared to the non-TMD group during maximal voluntary clenching (MVC).

Conclusion

There were differences in MMA in the TMD-pain population compared to a healthy control group during various tasks. The diagnostic efficacy of surface electromyography in assessing individuals with TMD-P remains unclear.

Ecological Momentary Assessment of Masseter Muscle Activity in Patients with Bruxism

According to the International Bruxism Consensus, bruxism refers to the activity of the masticatory muscles reflecting contraction disorders, regardless of whether it is during sleep (SB) or an awake (AB) state. The objective of the present study was to evaluate the activity of the masseter muscle by surface electromyographic (sEMG) recordings. This study was performed on 20 participants with self-reported “possible bruxism” (study group) and 20 participants with no self-reported bruxism (control group); all participants underwent an evaluation of the masseter muscle activity using the dia-BRUXO device, which provides numerical parameters regarding sEMG (the total duration and the type of bruxism specific events, the effort made by the masticatory muscles during the recording period, and the personal bruxism index of each participant). Participants from the study group presented more clenching events during AB, three times more frequent than the control group (p = 0.002, Mann−Whitney U test); for SB, the frequency of clenching and grinding events was comparable within the study group, being more frequent than for the control group; the mean value of the effort index was higher for AB (1.177%) than SB (0.470%) and the same for the duration index, with a mean value of 2.788% for AB and 1.054% for SB. All participants from the control group presented reduced values for all acquired parameters. Overall, the personal bruxism index in AB was approximately four times higher for the study group (2.251%) compared to the control group (0.585%) (p < 0.005, Mann−Whitney U test). Similar values were obtained for SB. All participants with “possible bruxism” from the study group presented a higher activity of the masseter muscle, which is specific for bruxism, thus being defined as “definite bruxism”.

Immediate Evaluation of the Effect of Infrared LED Photobiomodulation on Childhood Sleep Bruxism: A Randomized Clinical Trial

The gold standard for the management of sleep bruxism (SB) is the use of a rigid occlusal splint; however, there are limitations for its use in children and alternatives to the management of SB are needed. Photobiomodulation therapy has been used with positive results in temporomandibular disorders. This study aimed to evaluate the effects of photobiomodulation therapy with infrared LED in children with SB. Thirty children were divided into three groups: Group 1: control/absence of bruxism (n = 10); Group 2: SB treated with infrared LED (n = 10); Group 3: SB treated with occlusal splint (n = 10). Electromyographic evaluation of masseter, anterior temporalis, and upper trapezius, and salivary dopamine levels were assessed before and after treatments. Data were statistically analyzed using two-way mixed model ANOVA. An increase in the temporalis and right masseter EMG activity at rest was observed in Group 3, with large effect size (p < 0.05). Left masseter and temporalis EMG activity did not differ over time in the LED group, similar to the control group. Moreover, the EMG activity of masticatory muscles during chewing and upper trapezius muscle did not differ over time in all groups. The results also pointed to a difference in the levels of dopamine between children with and without SB, with Group 3 showing higher levels in the pre-treatment time compared to controls (p < 0.025). In conclusion, an increase in the masticatory muscles activity at rest was observed in children undergoing splint therapy. Moreover, a difference in the levels of salivary dopamine was found between children with and without SB.

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.

Electromyographic Study of Masticatory Muscle Function in Children with Down Syndrome

This study assessed the electrical activity of the masticatory muscles in both children with down syndrome (DS) and healthy children. After applying the inclusion and exclusion criteria, 30 patients aged between 7.9 and 11.8 years participated in the study. They were divided into two groups of 15: DS and non-DS. A DAB-Bluetooth device (Zebris Medical GmbH, Germany) was used to record the electromyographical (EMG) activity of the right and left temporal and of the right and left masseter muscles at rest and during maximum voluntary clenching (MVC). The asymmetry index between right and left masticatory muscle EMG activity was calculated for each position. The Mann–Whitney U test was applied to analyze the study results. There were no differences in the electrical activity of the temporal and masseter muscles at rest between the groups. During MVC, the asymmetry index for the masseter muscles was significantly higher in subjects with DS. The electrical potentials of the temporal and masseter muscles in children with DS were significantly lower compared to the corresponding parameters for healthy children when clenching.

Electromyographic evaluation of the effect of hard and soft stabilizing appliances on masseter and anterior temporalis muscles in asymptomatic individuals

Background/Aim: Stabilization appliances have traditionally been used for the treatment of temporomandibular disorders and bruxism. The aim of this study was to evaluate the effect of two appliances (hard and soft) with different thicknesses on the electromyographic (EMG) activities of masseter and anterior temporalis muscles. Material and Methods: 30 healthy subjects have been divided into two groups of 15, according to the appliance material used (soft, hard). For each subject in both groups, two appliances have been prepared with 3 mm and 6 mm thickness. EMG recordings of bilateral masseter and anterior temporalis muscles were taken for each appliance. Results: The results showed that, the decrease in average EMG values during maximum voluntary clenching with a 3-mm and 6-mm-thick hard appliance was statistically significant compared with the average EMG of maximum voluntary clenching in the intercuspal position. The increase in average EMG values during maximum voluntary clenching with a soft appliance of 3 mm and 6 mm thickness was statistically significant. Conclusions: The hard stabilization appliances decrease the activity of the masseter and temporalis muscles, while the soft appliances increase the activity of the masseter and temporalis muscles.

Effects of Therapeutic and Aerobic Exercise Programs on Pain, Neuromuscular Activation, and Bite Force in Patients with Temporomandibular Disorders

Pain in masticatory muscles is one of the most frequent symptoms in patients with temporomandibular disorders (TMD) and can lead to changes in the patterns of neuromuscular activity of masticatory muscles and decrease in bite force. This study assesses the effects of three eight-week exercise programs on pain intensity, neuromuscular activation, and bite force of masticatory muscles in patients with TMD. Forty-five patients were divided into three groups: a therapeutic exercise program (G1), a therapeutic and aerobic exercise program (G2), and an aerobic exercise program (G3). The masticatory muscles’ pain was evaluated using the numeric pain rating scale (NPRS), surface electromyographic (sEMG) activity of the masseter was recorded during maximum voluntary contraction and at rest, and bite force was evaluated using a dynamometer. These parameters were evaluated twice at baseline (A01/A02), at the end of the eight-week intervention period (A1), and 8–12 weeks after the end of the intervention (A2). After intervention, G2 showed the best results, with a significantly decrease in masticatory muscles’ pain and increase in bite force. These results suggest that interventions to reduce pain in patients with TMD should be multimodal.

The Relationship between Stress and Masticatory Muscle Activity in Female Students

The aim of the study was to analyze the relationship between stress measured by the perceived stress scale (PSS-10) questionnaire and masticatory muscle activity. Experimental design assumed the study of healthy young women without temporomandibular disorders, dividing them into three groups depending on the result of the stress level and then comparing these groups in terms of bioelectrical activity of the masticatory muscles. After the exclusion criteria were applied, 63 female students (mean age: 22.3 ± 2.4 years) from Medical University of Lublin were included in the study. The subjects were then divided into 3 groups: with low (n = 18), medium (n = 18) and high stress level (n = 27), according to PSS-10 results. Resting and functional activity of temporalis anterior (TA) and masseter (MM) muscles were measured by electromyograph BioEMG III. There were statistically significant effects of group on the absolute value of asymmetry index (AsI) of TA and MM during maximum voluntary clenching on dental cotton rollers (both p = 0.02). Post hoc analysis shows that there were statistically significant differences between medium and high stress groups in AsI TA (p = 0.01) and between low and high stress groups in AsI MM (p = 0.02). Perceived stress measured by PSS-10 questionnaire seems to be associated with changes in muscular asymmetry in functional clenching activity.

Electroporation technique for joint pain - Pilot feasibility study on TMD patients

Objective(s)

It is well appreciated that traditional analgesic delivery routes used to treat pain associated with temporomandibular disorder (TMD) often have harmful unintended side effects as a consequence of systemic distribution. Further, localized delivery of analgesic medication via intra‐articular injections involves a different set of issues limiting their clinical viability. As an option, transdermal analgesic delivery provides for prolonged pain relief and flexibility in dose administration, while limiting systemic exposure and minimizing adverse events. Incorporation of a novel electroporation technique may further increase transdermal drug penetration into synovial tissue/fluid and enhance pain reduction. The present feasibility study compares the effectiveness of an electroporation‐enhanced transdermal application of diclofenac sodium to a conventional intra‐articular injection of triamcinolone acetonide suspension (corticosteroids) to treat patients with TMD associated pain.

Methods

Pre‐ and post‐treatment maximal incisal mouth opening (MIO), pain visual analog scale (VAS) and surface electromyography (EMG) of 22 patients treated with electroporation‐enhanced diclofenac and 37 patients treated with corticosteroids injections were collected and analyzed.

Results

In general, patients treated with electroporation exhibited better results in terms of pain improvement (corrected p‐value = .01) compared to the standard treatment, but both methods were similarly effective for improvement of MIO (corrected p‐value = .71) and improvement of all EMG indices (corrected p‐values ≥ .05).

Conclusion

The enhancing effect of electroporation in transdermal delivery of diclofenac sodium was demonstrated by decreased pain, increase MIO and EMG improvement to normal values. Its analgesic and inflammatory results are comparable with standard treatment offered by corticosteroids.

Surface Electromyography as a Method for Diagnosing Muscle Function in Patients with Congenital Maxillofacial Abnormalities

Electromyography (EMG) is the most objective and reliable method available for imaging muscle function and efficiency, which is done by identifying their electrical potentials. In global surface electromyography (sEMG), surface electrodes are located on the surface of the skin, and it detects superimposed motor unit action potentials from many muscle fibers. sEMG is widely used in orthodontics and maxillofacial orthopaedics to diagnose and treat temporomandibular disorders (TMD) in patients, assess stomatognathic system dysfunctions in patients with malocclusions, and monitor orthodontic therapies. Information regarding muscle sEMG activity in subjects with congenital maxillofacial abnormalities is limited. For this reason, the aim of this review is to discuss the usefulness of surface electromyography as a method for diagnosing muscle function in patients with congenital malformations of the maxillofacial region. Original papers on this subject, published in English between 1995 until 2020, are located in the MEDLINE/PubMed database.

Electromyography as a Means of Assessing Masticatory Muscle Activity in Patients with Pain-Related Temporomandibular Disorders

Aim

The aim of this study was to evaluate masticatory muscle electrical activity in patients with pain-related and pain-free temporomandibular disorders (TMDs) as well as in subjects with no TMD.

Methods

Ninety children with mixed dentition were recruited to the study. Of this total, 30 subjects were diagnosed with pain-related TMD (TMD-P), 30 with pain-free TMD (TMD-PF), and 30 without TMD. We used Axis I of the Research Diagnostic Criteria for TMD (RDC/TMD) to assess the presence of TMD in the examined children. The electromyographical (EMG) potentials of the temporalis and masseter muscles were measured with a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) at rest and during maximum voluntary clenching (MVC).

Results

An analysis of the EMG recordings showed statistically significant intergroup differences in masticatory muscle electrical activity at rest and during MVC. Significantly higher rest temporalis muscle activity was noted in pain-related TMD subjects compared with that children from the pain-free TMD and non-TMD groups, as well as in TMD-PF children in relation to those without TMD. The EMG potentials of the temporalis muscle during MVC were much lower in patients with TMD-P than in pain-free TMD and non-TMD subjects. Masseter muscle activity at rest in the TMD-pain group was significantly greater, and masseter muscle EMG potentials during clenching were markedly lower than in patients with no TMD diagnosis.

Conclusion

The use of electromyography to assess masticatory muscle function revealed alterations in the pattern of temporalis and masseter muscle activity in patients with pain-related TMD compared with the pain-free subjects.

Estimation of jaw-opening forces, energy expenditure and jaw-opening patterns in adults

OBJECTIVES

The aims of this study were to investigate (1) the jaw-opening forces in different stages of jaw-opening, and determine the correlation among maximum jaw-opening force, maximum jaw-opening, and parameters such as age, height, weight, and gender, (2) the energy expenditure during jaw-opening, and (3) the jaw-opening patterns in adults.

DESIGN

This was a cross-sectional study. The sample consisted of 87 participants were recruited from Dunedin, New Zealand. Jaw-opening forces were measured using an adjustable, rigid extra-oral device connected to a 1000 N load cell.

MAIN RESULTS

Outcomes were highly skewed. The median (IQR) value of maximum jaw-opening was 48 mm (8 mm). The median of maximum jaw-opening force (40.0 N) was higher than jaw-opening force at maximum jaw-opening (35.2 N) (P < 0.01). The median (IQR) of the work was 1.30 J (1.28 J), ranging from 0.38 J to 4.03 J. The median of maximum jaw-opening force and work was higher in males (54.8 N; 1.22 J) than females (33.5 N; 0.74 J) (P < 0.05). Four jaw-opening force patterns (Pattern 1, 2, 3 and 4) were fitted and generated using Origin Pro software.

CONCLUSION

A wide range of variation in jaw-opening force and work was observed, and they displayed a non-parametric, highly skewed distributions. The maximum jaw-opening force did not correspond to the maximum jaw-opening. Further studies could explore the potential association among the jaw-opening force pattern, the work of jaw-opening and TMJ diseases.

The Diagnostic Value of Electromyography in Identifying Patients With Pain-Related Temporomandibular Disorders

Introduction: Orofacial pain disorders can be divided into several subgroups. One of them is temporomandibular disorders (TMD) with recognizable signs such as joint noises, limitations in the range of motion, or mandibular deviation during function and symptoms-pain in the muscles or joint. Surface electromyography (sEMG) is a diagnostic tool that ensures reliable and valid evaluation of muscle activity. sEMG detects electrical potentials and on this account may conceivably be employed in the TMD recognition. The aim of this study was to assess the sensitivity, specificity, and accuracy of electromyography in diagnosing subjects with temporomandibular disorders, including pain-free TMD and pain-related TMD. Methods: The sample comprised 88 patients with cleft lip and palate and mixed dentition. TMD has been recognized on the grounds of Axis I of the Research Diagnostic Criteria for TMD (RDC/TMD). To evaluate the electrical activity of the temporal and masseter muscles in the rest position and during maximum voluntary contraction, a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) was used. The analysis of the receiver operating characteristic (ROC) curve gave information about accuracy, cut-off point value, sensitivity and specificity of the normalized sEMG data. Results: The highest diagnostic efficiency of sEMG in terms of identifying subjects with TMD and pain-related TMD was observed for the mean values of temporal and masseter muscle activity as well as the Asymmetry Index of the masseter muscles in a rest position. A moderate degree of EMG accuracy in differentiating between pain-related TMD and non-TMD children was observed for the mean values of masseter muscle activity and the Asymmetry Index of the masseter muscles at rest. Conclusion: An evaluation of electromyography exhibits its diagnostic usability in recognition of patients with pain-related TMD and it could be used as an adjunctive tool in the identification of this disorder. Clinical Trial Registration: This clinical research was registered in the ClinicalTrials.gov database under the number NCT03308266.

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.

Evaluation of muscle activity, bite force and salivary cortisol in children with bruxism before and after low level laser applied to acupoints: study protocol for a randomised controlled trial

BACKGROUND

Bruxism is a repetitive activity that causes tooth wear, audible sounds, and discomfort. Preventive measures have been studied for conditions that can exert a negative influence on physiological development in children. Low-level laser therapy administered over acupoints is an effective, painless, low-cost treatment option that has achieved good results. Thus, the aim of the proposed study is to evaluate changes in muscle activity, bite force and salivary cortisol in children with bruxism after the application of low-level laser to accupoints.

METHODS

The children will be randomly allocated to four groups of 19 individuals: G1 - low-level laser; G2 - occlusal splint; G3 - placebo laser; and G4 - control (without bruxism). The BTS TMJOINT electromyography will be used to determine muscle activity and a digital gnathodynamometer will be used to measure bite force. Salivary cortisol will be analysed at baseline as well as one and six months after treatment. Two-way ANOVA will be employed and complemented by Tukey's test.

DISCUSSION

Bruxism is a repetitive activity of the masticatory muscles that can have negative consequences if not treated, such as tooth wear, noises, discomfort and anxiety. Thus, control and treatment measures should be taken. Although low-level laser therapy over acupoints has been indicated for children, the effects of this treatment modality have not yet been studied.

TRIAL REGISTRATION

NCT02757261 on 8 April 2016. This study protocol received a grant from the Brazilian fostering agency São Paulo Research Foundation (FAPESP: #2015/24731-0).

Effects of the functional orthopaedic therapy on masticatory muscles activity

Background

The purpose of this study was to examine surface electromyographic (sEMG) activity of masticatory muscles before and after functional orthopaedic therapy with Sander appliance.

Material and Methods

Ten adolescents (5 girls, 5 boys) with an Angle Class II, division I malocclusion, 9-13 years old, were submitted to sEMG before and after functional orthopaedic therapy. To verify the neuromuscular equilibrium, the standardized EMG activities of right and left masseter and anterior temporal muscles were recorded during maximum voluntary clench, and analysed calculating: POC (index of the symmetric distribution of the muscular activity determined by the occlusion); TC (index of presence of mandibular torque) and Ac (index suggesting the position of occlusal barycentre). The total muscular activity was also calculated. Pre- and post- functional therapy data were compared with Wilcoxon Signed-Rank Test.

Results

Before treatment, all subjects had a good neuromuscular equilibrium, which was not altered by treatment.

Conclusions

sEMG evaluations allow to quantify the impact of occlusion on masticatory muscle activity and to control that the functional orthopaedic therapy maintain a good muscular coordination.

Key words:Functional appliance, Sander appliance, electromyography, masticatory muscles.

Short-term transcutaneous electrical nerve stimulation reduces pain and improves the masticatory muscle activity in temporomandibular disorder patients: a randomized controlled trial

Studies to assess the effects of therapies on pain and masticatory muscle function are scarce.

[Masticatory apparatus disorder: how can rehabilitation treatment help?]

INTRODUCTION

The temporomandibular joint is highly adaptive and masticatory apparatus disorders (MAD) can occur when its ability to adapt is overwhelmed. Occlusal etiologies were long pinpointed as the sole culprits. However, a consensus now exists which minimizes their involvement. It is recognized that the etiology of MAD is multifactorial, combining occlusal problems, parafunctions, postural anomalies, orofacial dyspraxia and stress.

MATERIALS AND METHODS

In this article, the authors review the role of physiotherapy in managing these pathologies.

RESULTS

While it remains essential to treat the symptoms in order to relieve pain, optimum treatment requires the underlying pathogenic mechanisms to be identified. Rehabilitation treatment, therefore, offers a physiotherapy-based approach providing an etiological solution. By reeducating function, physiotherapy produces lasting results.

DISCUSSION

Given the multifactorial nature of MAD etiologies, maxillofacial rehabilitation is an indispensible ally for odontologists or orthodontists adopting a multidisciplinary approach in their treatment of this disorder.

[Temporomandibular joint disorders: Physiotherapy and postural approaches]

Rehabilitation of temporomandibular joint dysfunctions has for a long time tried to treat symptoms: pain relief, joint kinetics restoration, disk re-capture by manual maneuvers. The authors present their own therapeutic approach, which is no longer limited to symptoms, but addresses the causes and identifies risk factors to prevent relapse.

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

AIMS

To analyze and compare the electromyographic activity of the temporal (anterior portion) and masseter muscles among Karate-Dō 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-Dō athletes.

Assessment of electromyographic activity in patients with temporomandibular disorders and natural mediotrusive occlusal contact during chewing and tooth grinding

OBJECTIVES

The aim of this study was to investigate whether the presence of a natural mediotrusive contact influences electromyographic (EMG) pattern activity in patients with temporomandibular disorders (TMDs).

METHOD

Bilateral surface EMG activity of the anterior temporalis (AT), masseter (MM), and sternocleidomastoid (SCM) muscles was recorded in 43 subjects during unilateral chewing and tooth grinding. Thirteen patients had TMD and a natural mediotrusive contact (Group 1), 15 had TMD without a natural mediotrusive contact (Group 2), and 15 were healthy subjects without mediotrusive contacts (Group 3). All subjects were examined according to the Research Diagnostic Criteria for TMD (RDC/TMD). All EMG values were standardized as the percentage of EMG activity recorded during maximum isometric contraction on cotton rolls.

RESULTS

EMG activity from all muscles measured showed no significant differences between groups during chewing and grinding. Overall, in all groups, the EMG activity during chewing was higher in the working side than the non-working side in AT and MM muscles. During grinding, these differences were only found in masseter muscles (mainly in eccentric grinding). SCM EMG activity did not show significant differences during chewing and grinding tasks. Symmetry, muscular balance, and absence of lateral jaw displacement were common findings in all groups.

DISCUSSION

EMG results suggest that the contribution of a natural mediotrusive occlusal contact to EMG patterns in TMD patients is minor. Therefore, the elimination of this occlusal feature for therapeutic purposes could be not indicated.

Does the habitual mastication side impact jaw muscle activity?

OBJECTIVE

To compare electrical activity in the anterior temporal and masseter muscles on the habitual (HMS) and non-habitual mastication side (NHMS), during mastication and in the mandibular postural position. In addition, the increase in electrical activity during mastication was assessed for the HMS and NHMS, analysing both working (WSM) and non-working side during mastication (NWSM).

METHODS

A total of 28 healthy women (18-32 years) participated in the study. They were submitted to Kazazoglu's test to identify the HMS. Bioresearch 'Bio EMG' software and bipolar surface electrodes were used in the exams. The exams were conducted in the postural position and during the unilateral mastication of raisins, on both the HMS and NHMS. The working and non-working side on HMS and NHMS were assessed separately. The obtained data were then statistically analysed with SPSS 20.0, using the Paired Samples Test at a significance level of 95%.

RESULTS

The differences in the average EMG values between HMS and NHMS were not statistically significant in the postural position (Temporal p=0.2; Masseter p=0.4) or during mastication (Temporal WSM p=0.8; Temporal NWSM p=0.8; Masseter WSM p=0.6; Masseter NWSM p=0.2). Differences in the increase in electrical activity between the masseter and temporal muscles occurred on the working side, on the HMS and NHMS (p=0.0), but not on the non-working side: HMS (p=0.9) and NHMS (p=0.3). The increase in electrical activity was about 35% higher in the masseter than in the temporal muscle.

CONCLUSIONS

Mastication side preference does not significantly impact electrical activity of the anterior temporal and masseter muscles during mastication or in postural position.

Electromyography assessment in zygomaticomaxillary complex fractures

OBJECTIVE

The aim of this study was to assess the activity of the masseter and temporalis muscles using surface electromyography (EMG) in patients with zygomaticomaxillary complex (ZMC) fractures.

PATIENTS AND METHODS

This prospective study was carried out on 25 patients who had ZMC fractures. Fifteen patients were managed by open reduction and rigid fixation (ORIF) using titanium miniplates. This study, using surface electromyography, analyzed the activity of the masseter and temporalis muscles of 25 patients with ZMC fractures; 15 of them were surgically treated under general anesthesia (GA). Evaluations were made before surgery and 6 weeks after surgery by recording the mean of muscle contraction of 20 motor unit action potential (MUAP) against resistance, and statistical analyses were performed.

RESULTS

A significant EMG difference between the normal and ZMC fracture sides was found (P < 0.0001) for both masseter and temporalis muscles and was significantly improved after ORIF. However, postoperative EMV values of the repaired side was significantly less than measured postoperatively in the normal side (P < 0.0001) for both muscles.

CONCLUSION

ZMC fractures significantly diminish muscular activity of the masseter and temporalis and even though significant recovery of muscle activity was revealed after 6 weeks, it is still less than normal activity, highlighting the importance of postoperative rehabilitation.

Is the masticatory function changed in patients with temporomandibular disorder?

Patients with temporomandibular disorders (TMD) often complain and have limitation in masticatory function, which can be affected by a complex interaction of factors. The aim of this study was analyze the masticatory function in patients with TMD using surface electromyography (EMG) and masticatory efficiency (ME). Twenty-seven patients with TMD and 25 considered control (n), aged between 18 and 60 years, paired by age and gender, were evaluated according to RDC/TMD. In both groups were performed: EMG with chewing gum, clinical evaluation of habitual chewing with stuffed cookie (CE) (number of chewing strokes and time) and analysis of ME with fuchsin beads. Nonparametric statistical analyses were used (Mann-Whitney) for comparisons between groups, with 5% significance level. For all variables, the TMD group showed higher values than the control, with statistical significance for ME (p<0.0001), number of chewing strokes (p=0.04), chewing time (p=0.009), right masseter EMG activity (p=0.05), left masseter (p=0.005), right anterior temporal (p=0.05) and left anterior temporal (p=0.001). The conclusion is that patients with TMD showed changed chewing pattern, but without impairment of masticatory function.

Effects of intervertebral disc disorders of low back on the mandibular kinematic: kinesiographic study

Background

Intervertebral disc disorders are one of the most common causes of low back pain. Neuromuscular dysfunction frequently is present in patients with lumbar disc herniation.

When considering joint dysfunction, it is important to remember that the spine functions as a unit. Dysfunction on one level can trigger compensatory changes in other spinal levels or in other areas of the musculoskeleton. Findings demonstrated the relationship between stomatognathic and postural systems justifying the hypothesis that muscular-skeletal impairment in one system could affect the other one. However, evidence that a lumbar intervertebral disc herniation could influence the mandibular kinematics is still lacking. Aim of this study was to analyse the effects that intervertebral disc herniation of low back could have on the mandibular kinematics.

Findings

Kinesiographic evaluations of the mandibular dynamics of 23 adult patients suffering L4/L5 and L5/S1 lumbosacral disc hernation were compared with a non pathological control group. A statistically significant difference of maximal mouth opening (p < .05) and of maximal mouth opening velocity (p < .03) was found comparing the study patients with the control subjects.

Conclusion

Lumbosacral disc herniation appears to be associated with changes in the activity of mandibular kinematics both in rate and quality of movement. The study suggests the existence of connections between masticatory system and lumbar disk herniation.

An assessment of the usefulness of Kinesiograph as an aid in the diagnosis of TMD: a review of Manfredini et al.'s studies

AIM

Performing a literature review of publications by Dr. Manfredini et al. related to their temporomandibular joint (TMJ) injection therapy outcome with conclusions on the clinical utility of computerized measurement devices used in the management of temporomandibular disorders (TMDs). In addition, reviewing their published opinion on an occlusion: TMD versus a biopsychosocial paradigm for TMD. Manfredini et al. authored an article published in the Journal of the American Dental Association (JADA) 2013, "An Assessment of the usefulness of jaw kinesiography in monitoring temporomandibular disorders," the most recent of 12 articles. In all studies, subjects received TMJ injections with an objective measurement outcome criterion; increased maximum mouth opening (MMO) and subjective symptom improvement of pain and chewing function. In the 2013 JADA article, the Mandibular Kinesiograph, referred to as KG, measured MMO before and after therapy. In 11 prior articles, all subject groups with limited mouth opening exhibited very significant increased MMO post-treatment, documenting treatment success using the same 2013 protocol. The 2013 study showed a 1·1 mm improved MMO, described as insignificant. The authors did not critique or explain the aberrant, skewed 2013 outcome data contrasted with their prior studies, which showed overwhelmingly significant increased MMO. Instead, they concluded that the MMO recording device was clinically useless. This motivated a literature review of the authors' TMD publications.

CONCLUSION

The publications by Manfredini et al. recognized proponents of the psychosocial model of TMD, including the 2013 article, appear to be part of a campaign denying an occlusion: TMD relationship and disparaging the specific computerized measurement devices and the dentists using them in the management of their TMD patients using neuromuscular occlusion dental treatment.

Influence of temporomandibular disorder on temporal and masseter muscles and occlusal contacts in adolescents: an electromyographic study

Background

The aim of the present study was to analyse the influence of temporomandibular disorder (TMD) on electromyographic activity in the masseter and temporal muscles of adolescents and investigate a possible association with the number of occlusal contacts.

Methods

The Helkimo Index was administered for the diagnosis of TMD and classification of the adolescents into three groups: without TMD; with mild TMD; and with moderate/severe TMD. Carbon paper was used for the determination of occlusal contact points. A standardised electromyographic evaluation was performed on the masticatory muscles at rest, during habitual chewing and during maximum voluntary clenching. The readings were normalised to maximum voluntary clenching. Statistical analysis involved the chi-squared test and Fisher’s exact test. The Kruskal-Wallis test and one-way analysis of variance with Dunn’s post hoc test were used to compare differences between groups. Pearson’s correlation coefficients (r) were calculated for the determination of correlations between the number of occlusal contacts and RMS values.

Results

Electromyography revealed significant differences in the right and left masseter and temporal muscles at rest and during chewing among the three groups. These differences were not observed during maximum voluntary clenching. No statistically significant differences were found between the groups with and without TMD regarding the number of occlusal contacts.

Conclusion

Electromyographic activity in the masseter and temporal muscles was greater among adolescents with moderate to severe TMD.