Electromyographic indices, orofacial myofunctional status and temporomandibular disorders severity: A correlation study

Exploring botulinum toxin's impact on masseter hypertrophy: a randomized, triple-blinded clinical trial

The present study aimed to assess the effectiveness and functional adverse effects of a single and multiple injections of botulinum toxin A (BoNT-A) for masseter hypertrophy (MH). Twenty-six women complaining about lower third facial enlargement due to MH, received 75 U of BoNT-A (abobotulinum toxin) in each masseter muscles. After 3 months, patients were randomly assigned to receive a second treatment session of Saline Solution: (G1; n = 11) or BoNT-A: (G2; n = 12). Muscle thickness (ultrasound), electrical activity (electromyography; EMG), masticatory performance, and subjective perception of MH were evaluated. Follow-up was performed at 1, 3 and 6 months. Muscle thickness, EMG activity, and masticatory performance were analyzed using ANOVA two-way and Sidak test as post-hoc. Masticatory performance was analyzed by the Friedman's test and Mann-Whitney test. Regarding inter-groups comparisons, there was a significant decrease in the left masseter muscle thickness in the G2 group at the 6 month follow-up (p < 0.02). For EMG, significant differences were evident at the 6 month assessment, with higher masseter activity for G1 (p < 0.05). For masticatory performance, no significant differences were observed throughout the study (p > 0.05) and a higher improvement in subjective perception of MH was observed in the 1 month follow-up for G2 (p < 0.05). In conclusion, BoNT-A is effective for MH, however multiple injections cause functional adverse effects in masseter muscle.

Temporalis Muscle Changes Following Botulinum Toxin A Injections in Masseter Hypertrophy Patients: A Randomized Triple-Blinded Trial

BACKGROUND

This study aimed to elucidate the effects of botulinum toxin A (BoNT-A) treatment for patients diagnosed with masseter hypertrophy on the temporalis muscle, with a particular focus on assessing alterations in muscle thickness, electromyographic (EMG) activity, and the development of muscle pain.

METHODS

The present randomized triple-blinded clinical trial enrolled 26 female participants aged between 25 and 50 years complaining about masseter hypertrophy. Participants received 75U of BoNT-A (abobotulinumtoxinA) in both masseter muscles and after three months were randomized to receive a second treatment session of saline solution (S-BoNT-A) or BoNT-A (M-BoNT-A). Longitudinal assessments included temporalis muscle thickness through ultrasound, EMG activity, subjective pain, and masseter prominence severity after one, three, and six months of the first injection session. Muscle thickness, EMG, and subjective pain were analysed using two-way ANOVA with repeated measures and post hoc Sidak test, and for masseter prominence severity, Friedman and Mann-Whitney tests were used.

RESULTS

Regarding inter-group comparisons, a higher muscle thickness (p < 0.02) and a higher EMG activity (p < 0.01) were found in the M-BoNT-A group at the 6-month follow-up. For subjective pain assessments, inter-group comparisons showed a higher prevalence of painful regions in M-BoNT-A group at the 6-month follow-up (p < 0.02). No significant differences were found in masseter prominence severity at the 6 months assessment between groups.

CONCLUSION

BoNT-A treatment for masseter hypertrophy lead to structural and functional changes in the temporalis muscle, presenting higher changes after multiple injections of this treatment.

LEVEL OF EVIDENCE I

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Evaluation of functional interaction masseter and sternocleidomastoid muscles affected by TMJ dysfunction

OBJECTIVE

Aim: To evaluate the functional connection and the bioelectrical state of the m.masseter and m. sternocleidomastoid using functional tests before and after treatment.

PATIENTS AND METHODS

Materials and Methods: The sample consisted of 21 individuals with temporomandibular joint dysfunction. Examinations were carried out before and after treatment using repositioning splint therapy and in seated/standing positions.

RESULTS

Results: M. masseter - p=0.072 before treatment and p=0.821 after treatment. Symmetry is also maintained after treatment. After treatment, a significant difference is noted at the level of significance p<0.001 for the right chewing muscle. In seated and standing positions before treatment did not reveal a statistically significant difference (p=0.07, p=0.143) and after (p=0.272, p=0.623).M. sternocleidomastoid- p<0.001 when comparing right and left sides. After treatment, there was no difference between the right and left sides (p=0.169). No statistical difference was found when assessing indicators separately for the right and left muscles in seated and standing positions (p=0.304, p=0.611, p=0.089, p=0.869). When comparing the bioelectric potentials of the right muscle before, after treatment, a statistically significant difference was found p=0.001.

CONCLUSION

Conclusions: Biostatistical analysis of the indicators of bioelectrical activity of m. masseter and sternocleidomastoid indicates no changes in muscle microvolt indicators with changes in body position in patients. However, repositioning splint therapy is associated with reduced muscle tone in initially more spasmodic muscles. It is worth noting that the symmetry of interaction between muscles improves.

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.

Surface electromyography evaluation of selected manual and physical therapy interventions in women with temporomandibular joint pain and limited mobility. Randomized controlled trial (RCT)

Non-invasive approach is gaining an increasing recognition in the TMD patients management. It is therefore reasonable to conduct RCTs evaluating the effectiveness of both physical and manual physiotherapy interventions. The aim of this study was to evaluate the short-term efficacy of selected physiotherapeutic interventions and their effect on the bioelectrical function of the masseter muscle in patients with pain and limited TMJ mobility. The study was conducted on a group of 186 women (T) with the Ib disorder diagnosed in DC/TMD. The control group consisted of 104 women without diagnosed TMDs. Diagnostic procedures were performed in both groups. The G1 group was randomly divided into 7 therapeutic groups in which the therapy was carried out for 10 days: magnetostimulation (T1), magnetoledotherapy (T2), magnetolaserotherapy (T3), manual therapy- positional release and therapeutic exercises (T4), manual therapy - massage and therapeutic exercises (T5), manual therapy - PIR and therapeutic exercises (T6), self therapy - therapeutic exercises (T7). In the T4 and T5 groups, the treatments led to complete resolution of pain after the 10th day of therapy and to the largest minimal clinically significant difference in the MMO and LM parameter. GEE model for PC1 values using treatment method and time point showed that T4, T5 and T6 treatments had the strongest effect on the parameters studied. Therefore, it may be concluded that SEMG testing is a helpful indicator to assess the therapeutic effectiveness of physiotherapeutic interventions.

BACKGROUND

Non-invasive approach is gaining an increasing recognition in the TMD patients management. It is therefore reasonable to conduct RCTs evaluating the effectiveness of both physical and manual physiotherapy interventions in a qualitative and quantitative manner. However, there were numerous controversies reported regarding the use of surface electromyography (SEMG) in Orofacial Pain patients. Therefore, we wanted to assess the effectiveness of physiotherapy interventions in TMD patients using SEMG.

PURPOSE

Evaluation of the short-term efficacy of selected physiotherapeutic interventions and their effect on the bioelectrical function of the masseter muscle in patients with pain and limited TMJ mobility.

MATERIAL AND METHODS

The study was conducted on a group of 186 women (T) with the Ib disorder diagnosed in DC/TMD (Ib - myofascial pain with restricted mobility). The control group consisted of 104 women without diagnosed TMDs (normal reference values for TMJ ROM and masseter muscle SEMG bioelectric activity). Diagnostic procedures were performed in both groups (SEMG of the masseter muscles at baseline and during exercise, measurement of TMJ mobility, assessment of pain intensity - NRS scale). The G1 group was randomly divided into 7 therapeutic groups in which the therapy was carried out for 10 days: magnetostimulation (T1), magnetoledotherapy (T2), magnetolaserotherapy (T3), manual therapy- positional release and therapeutic exercises (T4), manual therapy - massage and therapeutic exercises (T5), manual therapy - PIR and therapeutic exercises (T6), self-therapy - therapeutic exercises (T7). Each time after therapy, the intensity of pain and TMJ mobility were assessed. Sealed, opaque envelopes were used for randomization. After 5 and 10 days of therapy, bilateral SEMG signals of the masseter muscles were acquired. PC1 factor analysis was performed. A score of 99% in the PC1 parameter, demonstrates the clinical relevance of electromyography (MVC).

RESULTS

Synergism of physical factors will lead to a higher MID on the NRS scale. Evaluating the MID of the therapeutic interventions used showed a better therapeutic effect of manual interventions over physical and self-therapy. In the T4 and T5 groups, the treatments led to complete resolution of pain after the 10th day of therapy and to the largest minimal clinically significant difference in the MMO and LM parameter. GEE model for PC1 values using treatment method and time point showed that T4, T5 and T6 treatments had the strongest effect on the parameters studied.

CONCLUSIONS

1. Exercise SEMG testing is a helpful indicator to assess the therapeutic effectiveness of physiotherapy interventions. 2. Manual therapy treatments are superior to physical treatments in their relaxation and analgesic efficacy and should therefore be prescribed as a first line non-invasive intervention for TMD pain patients.

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.

Effect of sound-induced repeated stress on the development of pain and inflammation in the temporomandibular joint of female and male rats

Temporomandibular disorder (TMD) is a common painful condition of the temporomandibular joint (TMJ) and associated structures. Stress is a significant risk factor for developing this painful condition that predominantly affects women. This study aimed to test the hypothesis that stress increases the risk of developing TMJ pain by facilitating inflammatory mechanisms in female and male rats. To test this hypothesis, we evaluated TMJ carrageenan-induced expression of pro-inflammatory cytokines and migration of inflammatory cells and TMJ formalin-induced nociception in female and male rats submitted to a repeated stress protocol induced by sound. We found that sound-induced repeated stress facilitates TMJ inflammation and contributes to TMJ nociception development equally in females and males. We conclude that stress is a risk factor for developing painful TMJ conditions in males and females, at least in part, by favoring the inflammatory process similarly in both sexes.

Masticatory Function in Individuals with Temporomandibular Disorders: A Systematic Review and Meta-Analysis

The literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol in the PubMed, Cochrane Library, LILACS, EBSCO, Scielo, between 2012 and 2022. The methodological quality was assessed by using the Newcastle-Ottawa Study Quality Assessment Scale. Mean differences and 95% confidence intervals were calculated and combined in meta-analyses. A total of 1202 participants were included in this systematic review (690 with TMD; 512 without TMD), with 22 articles being included in the qualitative analysis. Only three studies enabled the comparative analysis of the results. Ten articles showed a high methodological quality and a low risk of bias, and twelve had a low methodological quality and an increased risk of bias. The meta-analysis showed that the differences between the intervention and control groups were not statistically significant for the percentage overlapping coefficient of the anterior temporal muscle, for the masseter, and for the torque coefficient. The parameters analyzed with the compound technique for chewing showed altered mandibular functions in individuals with TMD. With the EMG method, it was possible to suggest that TMD in adult individuals causes compensatory muscle behaviors, and several changes in the masticatory function were found.

The accuracy and reliability of the Turkish version of the Fonseca anamnestic index in temporomandibular disorders

OBJECTIVE

To determine the reliability and diagnostic accuracy of the Turkish version of the Fonseca anamnestic index (FAI-T).

METHODS

The cultural equivalence of the FAI was established according to the International Network for Orofacial Pain and Related Disorders Methodology. The test-retest reliability, internal consistency, and diagnostic accuracy of the FAI-T was carried out in a sample of 66 controls and 139 patients with TMD. Diagnostic accuracy of the FAI-T was evaluated against the Research Diagnostic Criteria for Temporomandibular Disorders.

RESULTS

Internal consistency analysis resulted in a Cronbach's alpha coefficient of 0.805. The intraclass correlation coefficient (ICC) values of each index question ranged from 0.739 to 0.897. FAI had a high level of accuracy (area under the ROC curve of 0.928).

CONCLUSION

The results provide considerable evidence that the FAI-T can be used as a screening tool for the identification of TMD in Turkish-speaking populations.

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.

Is there an association between EMG activity and temporomandibular disorders during orthotic mandibular advancement in sleep apnea patients undergoing DISE?

OBJECTIVE

To detect whether myotatic reflex activation of masticatory muscles during drug-induced sleep endoscopy (DISE) can be an indirect marker for temporomandibular disorder (TMD) in patients suffering from obstructive sleep apnea (OSA).

METHODS

OSA patients were prospectively recruited and underwent a complete TMD examination prior to undergoing DISE with the addition of electrodes applied over masticatory muscles. A positive activation of myotatic reflex was considered in case of an increase in muscle tone of at least 50%.

RESULTS

Of the 41 patients included, 48.8% presented activation of myotatic reflex. Of these patients, 45% presented a TMD diagnosis, 40% presented pain at masticatory muscles palpation, and 15% did not report pain during clinical examination.

CONCLUSION

An increase in EMG activity during mandibular advancement is not associated with TMD presence, but it can be an indirect marker of pain in the orofacial area in OSA patients.

Cervical Myofascial Pain Is Associated with an Imbalance of Masticatory Muscle Activity

This study aimed to assess the relationship between the occurrence of cervical myofascial pain with active myofascial trigger points (MTrPs) within the upper trapezius muscle and the electromyographic asymmetry index (AsI) of masticatory muscles: temporalis anterior (TA), superficial part of the masseter muscle (MM), and anterior belly of the digastric muscle (DA). The study group comprised 100 subjects (80 women and 20 men) aged 18 to 30 years (mean 23 ± 2.6 years) reporting pain in the neck muscles, diagnosed with myofascial pain with active MTrPs only within the upper trapezius muscle. The control group comprised 60 healthy, pain-free subjects (42 women and 18 men) aged 20 to 30 years (mean 22.8 ± 2.6 years) without MTrPs in the upper trapezius muscle. The palpation measurement, based on the diagnostic criteria of Travell and Simons, was used to diagnose active MTrPs. The masticatory muscle activity was recorded using an 8-channel device for surface electromyography—BioEMG III^TM. Significant differences in electromyographic patterns between the group with MTrPs in the right side of upper trapezius muscle and the control group were observed within resting activity for the AsI TA (MTrPs: 8.64 vs. controls: −3.22; p = 0.001) and AsI MM (MTrPs: 7.05 vs. controls: −2.09; p = 0.018). Controls presented different electromyographic patterns during maximum voluntary clenching with cotton rolls between teeth within masseter muscle compared to the MTrPs group (MTrPs: 9.27 vs. controls: −0.43 vs. p = 0.041). Participants with MTrPs in the left side of upper trapezius muscle presented predomination of left-sided electromyographic patterns at rest within temporalis anterior in comparison to controls (MTrPs: −19.22 vs. controls: −3.22; p = 0.001). MTrPs within the trapezius muscle may be related to asymmetry within the masticatory muscle activity, suggesting that the presence of myofascial pain within the cervical muscles plays a role in the imbalance of the stomatognathic system. A unilateral active MTrPs within the trapezius muscle may increase the sEMG activity on the same side of the temporalis anterior and masseter muscles.

Immediate effects of rhythmic joint mobilization of the temporomandibular joint on pain, mouth opening and electromyographic activity in patients with temporomandibular disorders

BACKGROUND

Rhythmic joint mobilizations (RJM) of the temporomandibular joint (TMJ) are employed to relieve pain and improve function in patients with temporomandibular disorders (TMD). However, the evidence on the immediate effects of RJM in patients with TMD is scarce. The aim of this study was to assess the immediate clinical and functional effects of RJM in patients with TMD.

MATERIALS AND METHODS

This was a one-group quasi-experimental before and after study. Thirty-eight patients with TMD were assessed by means of pain intensity (visual analogue score, VAS), pressure pain threshold (PPT, measured through pressure algometry on the masseter and temporal muscles), mouth opening (MO, measured with a ruler), and surface electromyographic activity of the masseter and temporal muscles (asymmetry index, AI). Measurements were performed before and after a single, 1-min session of RJM of each TMJ. All statistical analyses were performed using the SPSS version 20.0 statistical package.

RESULTS

A statistical significant difference was found in pain intensity, PPT and MO after the intervention (p < 0.05). No difference was found in the AI. A large effect size was observed for pain intensity, PPT of the left and right masseter muscles and MO (d = 0.85-1.13), whereas for the left and right temporal muscles the effect size was moderate (d = 0.62) and small, respectively (d = 0.49).

CONCLUSION

In this sample of patients with TMD, a single session of RJM of the TMJ seemed to be effective in reducing pain intensity, increasing PPT and improving MO immediately after the intervention, without differences in the AI.

Electromyography-Guided Adjustment of an Occlusal Appliance: Effect on Pain Perceptions Related with Temporomandibular Disorders. A Controlled Clinical Study

Background: The purpose of this study is to evaluate the effect of an electromyography-guided adjustment of an occlusal appliance on the management of Temporomandibular disorder-related pain. Methods: Data from 40 adult patients (20 males and 20 females), who underwent treatment with occlusal appliances, were recorded. A total of 20 appliances were adjusted according to electromyographic data (group 1), while the others were adjusted by a clinical conventional procedure (group 2). Muscle pain to palpation, pain during articular movements and headache were recorded by a VAS score (from 0 to 100) before the beginning of treatment (T0), at T1 (4 weeks) and T2 (8 weeks). Results: Results showed a reduction of pain in both groups, with a better trend for group 1, where better results were achieved at T1 and maintained stability at T2, with an improved mean value regarding all parameters studied. After 8 weeks, only small recurrences started to occur in muscle pain to palpation in group 2. Conclusions: An occlusal appliance seems to be able to achieve a clinical improvement of Temporomandibular disorder (TMD)-related pain and headache, independently from the adjustment procedure adopted. However, the use of a surface electromyographic activity of masticatory muscles (sEMG) device as an aid in the calibration procedure seems to allow a better trend because the improvement of symptoms was obtained before, after the first four weeks, with an improvement in percentages of all the variables investigated. While the conventional procedure obtained later the improvement.

Masticatory performance is influenced by masticatory muscle activity balance and the cumulative occlusal contact area

OBJECTIVE

To investigate the influence of masticatory muscle activity balance, occlusal contact area balance and the area of occlusal contact on masticatory performance in healthy dentate adults.

DESIGN

This cross-sectional study included ninety-three healthy subjects with complete dentition. Surface electromyography (sEMG) was used to record bilateral anterior temporalis activity and masseter muscle activity during maximum voluntary clenching and while chewing a test food. Seven levels of area of occlusal contact and near contact (ACNC) were registered and calculated cumulatively. The percentage overlapping coefficients were calculated for both muscle groups at maximum voluntary clenching and chewing and all levels of ACNC. Masticatory performance was measured by determining the median particle size of frankfurter sausage after 15 chewing cycles. Pearson's correlation and stepwise multiple linear regression analyses were used to assess the correlations between variables and the influence of the variables on masticatory performance, respectively, at the 0.05 level of significance.

RESULTS

Muscle balance during clenching and chewing, all near contact levels of cumulative ACNC and ACNC balance correlated negatively with median particle size (P <  0.05). The model based on stepwise multiple linear regression analysis showed muscle balance during clenching and cumulative ACNC at < 250 μm influenced median particle size.

CONCLUSION

Masticatory muscle activity balance during maximum voluntary clenching and the cumulative amount of near contact area were associated with masticatory performance, suggesting the amount of occlusal contact area-as well the balance of masticatory muscle activity-play a role in masticatory performance.

Comparison of the pattern of activation of the masticatory muscles among individuals with and without TMD: A systematic review

OBJECTIVE

To verify the characteristics of the electromyographic signal of masticatory muscles in individuals with TMD and asymptomatic individuals.

METHODS

A systematic review was carried out, selecting cross-sectional studies with at least one electromyographic parameter (FM; iEMG; RMS) of the masticatory muscles (anterior temporal, bilateral masseter, and suprahyoid muscles) of individuals with TMD compared to asymptomatic individuals.

RESULTS

This review identified 1656 titles, of which 30 articles were included in the final analysis. It was observed that the data referring to the pattern of activation of masticatory muscles in the rest, isometry, and isotonic conditions of individuals with TMD are heterogeneous. This fact may be related to variability in the methods and analyses applied in the studies.

CONCLUSION

Data referring to the pattern of activation of masticatory muscles in the rest and isometry conditions and in the mastication cycle of individuals with TMD and asymptomatic individuals are diverse.

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.

Efficacy and Safety of Botulinum Toxin Type A on Persistent Myofascial Pain: A Randomized Clinical Trial

This study assessed the safety and efficacy of three different doses of BoNT-A for persistent myofascial pain (MFP). One hundred female subjects were randomly assigned into five groups (n = 20): oral appliance (OA), saline solution (SS) and three BoNT-A groups with different doses. Pain intensity and pressure pain threshold were evaluated up to 24 weeks after treatment. Adverse effects related to muscle contraction, masticatory performance, muscle thickness and mandibular bone volume were also assessed. Changes over time were compared within and between groups. The “nparLD” package and Wilcoxon signed-rank test were used to analyze the data. BoNT-A reduced pain intensity (p < 0.0001) and increased pressure pain threshold (p < 0.0001) for up to 24 weeks compared to the placebo. No differences were found between BoNT-A and OA at the last follow-up. A transient decline in masticatory performance (p < 0.05) and muscle contraction (p < 0.0001), and a decrease in muscle thickness (p < 0.05) and coronoid and condylar process bone volume (p < 0.05) were found as dose-related adverse effects of BoNT-A. Regardless of the dose, BoNT-A was as effective as OA on MFP. Notwithstanding, due to BoNT-A dose-related adverse effects, we suggest the use of low doses of BoNT-A in MFP patients that do not benefit from conservative treatments.

Tongue function and swallowing in individuals with temporomandibular disorders

The tongue participates in the oral phase of swallowing by pushing the food bolus toward the oropharynx. This relationship between tongue function and swallowing is little addressed addressed in individuals with temporomandibular dysfunction (TMD).

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.

Can the severity of orofacial myofunctional conditions interfere with the response of analgesia promoted by active or placebo low-level laser therapy?

OBJECTIVE

To analyze the influence of orofacial myofunctional condition (OMC) on pain perception, temporomandibular disorders (TMD) severity, and the response to low-level laser therapy (LLLT) in women with painful TMD.

METHODS

Seventy-eight women, 59 with TMD, received active laser (30) or placebo (29), with 19 controls. OMC, TMD severity, pain intensity, and pressure pain threshold (PPT) were assessed at different times during the masticatory test: before treatment (LLLT dose: 780nm), during, and after 30 days.

RESULTS

No correlation was found between OMC and pain perception or TMD severity (p > 0.05). The active and placebo LLLT showed reduction of pain during chewing and better recovery levels during the rest period (p > 0.05), without differences between OMC groups.

DISCUSSION

The perception of pain and severity of TMD are not correlated with the OMC, and the response of analgesia promoted by active LLLT or placebo is not associated with OMC.

The prevalence of oral stage dysphagia in adults presenting with temporomandibular disorders: a systematic review and meta-analysis

OBJECTIVE

Temporomandibular disorders (TMDs) are the most commonly experienced non-dental orofacial pain disorders, with pain and dysfunction potentially resulting in oral stage dysphagia (OD). However, limited research has been conducted on this condition, with potential negative effects on clinical practice. Therefore, the aim of this study was to determine the prevalence of OD in adults presenting with TMDs, diagnosed as per the Research Diagnostic Criteria for Temporomandibular Disorders or the Diagnostic Criteria for Temporomandibular Disorders protocols.

MATERIAL AND METHODS

A systematic review of the literature was completed. Nine electronic databases were searched from inception to January 2017, with no date/language restriction applied. Grey literature, conference proceedings, and reference lists were also searched. Studies presenting original data regarding OD prevalence in adults presenting with TMDs were included if they investigated impaired swallowing, mastication, masticatory pain or fatigue, or weight loss. Study eligibility and quality were assessed by two independent reviewers. Methodological quality was assessed using the Down's and Black tool.

RESULTS AND CONCLUSIONS

This search yielded 20 eligible studies. Swallowing itself was impaired in only 9.3% of patients with TMDs. A range of additional OD signs and symptoms were also commonly reported (e.g. masticatory pain (87.4%) and fatigue (62%)). Study limitations included the small number of studies which were eligible for inclusion. As signs and symptoms of OD are frequently reported by patients with TMDs, psychometrically robust prospective research is warranted to determine current and optimal management of this condition.

Swallowing and Temporomandibular Disorders in Adults

INTRODUCTION

Temporomandibular disease (TMD) etiology is multifactorial and is related to many perpetuating, predisposing, and initiating factors. The daytime parafunctions may have an important role in TMD pathogenesis. The most frequent parafunctions analyzed were the static parafunction (ie, clenching) and the dynamic parafunction (ie, grinding). In the present paper, the authors evaluated the swallowing (an oral function/parafunction) with the surface electromyography in patients with TMD.

MATERIALS AND METHODS

Twenty patients with TMD problems (nonhealthy patients, NHP) (mean age: 33 ± 1.994; 8 men and 12 women) and 20 healthy matched subjects (HP) (34.4 ± 2.782; 6 men and 14 women) were selected and examined. On each patient, an 8-channel surface electromyography was done during saliva swallowing.

RESULTS

Nonhealthy patients presented higher masseter and temporalis activation (P < 0.05) and an unbalancing of temporalis and submental muscles activation (P < 0.05) than the HP.

DISCUSSION

Nonhealthy patients presented a time of swallow higher than HP (P < 0.001). Nonhealthy patients presented a higher muscles activation and time of swallow than HP and a decrease of muscles balancing activation.

Orofacial motor functions in pediatric obstructive sleep apnea and implications for myofunctional therapy

OBJECTIVES

The purposes of this study were (1) to identify possible differences in muscular and orofacial functions between children with obstructive sleep apnea (OSA) and with primary snoring (PS); (2) to examine the standardized difference between normal values of myofunctional scores and those of subjects with OSA or PS; and (3) to identify the features associated with OSA.

METHODS

Participants were 39 children (mean age 8 ± 1.2 years) of which, 27 had a diagnosis of OSA and 12 had PS. All participants were examined by an otorhinolaryngologist and underwent overnight polysomnography. Orofacial characteristics were determined through a validated protocol of orofacial myofunctional evaluation with scores (OMES), surface electromyography of masticatory muscles, and measurements of maximal lip and tongue strength. Reference values in the OMES were included to quantify the standardized difference (effect size = ES) relative to the groups studied and in the regression analysis.

RESULTS

The OSA group had lower scores in breathing and deglutition, more unbalanced masticatory muscle activities than PS group (P < 0.05), but both groups had similar reductions in orofacial strength. OSA had a large ES (Cohen's d > 0.8) in all analysed OMES scores, while PS group showed small and medium differences in breathing and mastication scores, respectively. The mobility of the stomatognathic components score was the most important to contribute for group status (57%, P < 0.0001) in the regression analysis.

CONCLUSION

Children with tonsillar hypertrophy and OSA had relevant impairments in orofacial functions and lesser muscular coordination than children with PS.

Signs and symptoms of temporomandibular disorders in women and men

INTRODUCTION

Women are more likely to present temporomandibular disorders (TMD); however, studies comparing genders in Brazilian samples are rare.

PURPOSE

To analyze the proportion of men and women, as well as the association between gender and age, problem duration, and TMD symptoms in patients admitted to an university clinic for treatment.

METHODS

Interview and assessment data of protocols from 1,000 patients diagnosed with TMD were collected and analyzed and then divided into two groups, male (n = 177) and female (n = 823). The exploratory analysis was based on contingency tables and χ2 test was carried out. Subsequently, the logistic regression model was used and the odds ratios (OR) concerning the evaluated comparisons were calculated.

RESULTS

Females were more prevalent in the sample, and mean ages and TMD duration were similar between the groups, with higher occurrence in young adults (19 to 40 years old). The OR values showed an association between the female gender and the signs/symptoms of pain in the temporomandibular joint, pain in the facial muscles, neck and shoulders, headache, fatigue in the muscles of mastication, otologic symptoms, and dysphonia. Women had two times higher chances of presenting these symptoms than men.

CONCLUSION

In the sample of Brazilian patients with TMD, the number of women who presented a higher prevalence of painful symptoms was greater, followed by otologic symptoms and complaints of dysphonia. The prevalence of joint noise was similar in both studied groups.

Uses of electromyography in dentistry: An overview with meta-analysis

OBJECTIVE

The purpose of this study was to review the uses of electromyography (EMG) in dentistry in the last few years in related research. EMG is an advanced technique to record and evaluate muscle activity. In the previous days, EMG was only used for medical sciences, but now EMG playing a tremendous role in medical as well as dental sector.

MATERIALS AND METHODS

Several electronic databases such as Google Scholar, PubMed, Science Direct, and Web of Science were systematically searched for studies published until July 2015.

RESULTS

EMG can be used in both diagnosis and treatment purpose to record neuromuscular activity. In dentistry, we can utilize EMG to evaluate muscular activity in function such as chewing and biting or parafunctional activities such as clenching and bruxism. In case of TMJ and myofascial pain disorders, EMG widely is used in the last few years.

CONCLUSIONS

EMG is one of biometric tests that occur in the modern evidence-based dentistry practice.

Effect of the Pilates method on women with temporomandibular disorders: A study protocol for a randomized controlled trial

BACKGROUND

There is no consensus regarding the influence of temporomandibular disorders (TMD) on postural changes, but it is believed that an imbalance in one may influence the other. The aim of this study is to evaluate changes in the level of pain, the severity of TMD, the EMG activity of masticatory muscles and posture of young women undergoing training in Pilates, as well as correlating postural changes, pain level, severity of TMD and EMG activity of masticatory muscles.

METHODS/DESIGN

A randomized clinical trial with blinded assessors will be held. 40 patients divided randomly into two groups will be assessed. The control group will receive conventional treatment with occlusal splint while the intervention group, in addition to conventional treatment will participate in Pilates sessions. Both groups will consist of women aged 18-35 years with TMD and pain. The research follow-up period will be 15 weeks.

Translation and cross-cultural adaptation of the protocol of orofacial myofunctional evaluation with scores for Italian Language

The protocol of orofacial myofunctional evaluation with scores (OMES-protocol or AMIOFE in Portuguese language) is a validated instrument for the diagnosis of orofacial myofunctional disorders that can be used in clinical practice for speech-language pathologists. Because in the Italian language there is no validated tool for such purpose, this study was developed.

PURPOSES

To translate and culturally adapt the OMES-protocol for Italian language and determine the normal score value in a group of young Italian adults.

METHODS

The OMES-protocol was translated from English to Italian by three bilingual individuals. From these translations, a consensus version was prepared by a research committee (three speech therapists and one physician and submitted to a committee of judges composed by eight speech therapists experienced in the area. The authors of the original version verified and approved the Italian version of the protocol. The instrument was tested via evaluations of 40 young and grown-up Italians (age range: 18-56 years) performed by two speech therapists. A cutoff score, previously described, was used to determine the mean and standard deviation.

RESULTS

The translation stage and the final Italian version of the OMES-protocol are shown. The mean of scores for individuals with and without orofacial myofunctional disorders were presented.

CONCLUSION

The Italian version of the OMES-protocol was developed, translated, and cross-culturally adapted. Normal values for young and adult Italian subjects are presented.