Assessment of thickness and function of masticatory and cervical muscles in adults with and without temporomandibular disorders

Assessment of Reliability, Agreement, and Accuracy of Masseter Muscle Ultrasound Thickness Measurement Using a New Standardized Protocol

There is no validated method of assessing masseter muscle thickness (MMT) by ultrasound imaging (US). However, this is important to ensure study and measurement quality of MMT by US in future studies, as MMT differs depending on the examined area. Thus, this study's aim was to present a new standardized method for assessing the MMT by US and to evaluate the reliability, consistency, and accuracy of its measurements. We also compared the results of MMT measurements obtained by US and computer tomography (CT). The study included nine healthy adults. The US and CT scans were collected in a supine rest position with the mandible in relaxed position. US measurements were determined according to a new standardized protocol (with precise probe location). The MMT measured by CT and US over a seven-day interval showed excellent intra-rater reliability. The mean MMT measured by CT was 12.1 mm (1.74) on the right side and 11.9 mm (1.61) on the left side. The mean MMT measured by US was 12.7 mm (2.00) on the right side and 11.5 mm (1.37) on the left side. The mean percent error in MMT measurement between CT and US was below 6%. A strong linear relationship was found between the CT and US measurements of the MMT on both body sides (p < 0.001, r ≥ 0.93). The proposed method of MMT measurement using US demonstrated excellent reliability, yielding results similar to those obtained from CT images. We recommend the use of this standardization protocol in further studies where precise assessment of MMT by US is expected.

Evaluation of the thickness of masticatory muscles in patients with chronic periodontitis by ultrasonography

OBJECTIVES

Periodontitis is one of the most common chronic inflammatory diseases. It causes changes in the biting abilities of individuals. However, periodontal treatment has positive effects on masticatory function. The aim of this study is to determine the effect of periodontitis and periodontal treatment on masticatory abilities by measuring masseter and temporal muscle thicknesses with ultrasonography before and after periodontal treatment in chronic periodontitis patients.

METHODS

The patients included in the study were determined by clinical and radiological examination. The thickness of the masseter and temporal muscles of the patients were measured by ultrasonography. Periodontal measurements and treatments of the patients were completed by a single physician. IBM SPSS 20.0 (IBM Corp., Armonk, NY) statistical program was used for statistical analysis.

RESULTS

A statistically significant difference was found between the values of periodontal measurements before and after treatment (p<0.05). In the ultrasonography measurements of the thickness of masseter and anterior temporal muscles, a statistically significant increase was observed in both rest and contraction values at all time intervals (p<0.05). Muscle thicknesses of male patients were higher than female patients.

CONCLUSIONS

Periodontitis negatively affects the masticatory performance of individuals. Chronic periodontitis patients should be referred for periodontal treatment without wasting time.

Evaluation of the efficacy of pharmacological treatment in patients with temporomandibular joint dysfunctions using ultrasonography

STATEMENT OF PROBLEM

Temporomandibular joint dysfunctions (TMDs) are complex problems affecting the temporomandibular joints (TMJs), masticatory muscles, or both. TMDs are considered muscle pain caused by contraction and ischemia in the masticatory muscles, but evaluation of the efficacy of pharmacological treatment is lacking.

PURPOSE

The purpose of this clinical study was to evaluate the changes in masticatory muscles, joint space, and main arteries supplying the TMJs after pharmacological therapy in patients with TMDs using ultrasonography (USG).

MATERIAL AND METHODS

The TMJ space, masseter and temporal muscles, temporal superficial artery (TSA), and facial artery (FA) were examined using USG in 30 participants with acute TMD pain before and after 10 days of symptomatic treatment with analgesic and myorelaxant. The bilateral masseter and temporal muscle thicknesses, joint space, and end-diastolic minimum velocity (Ved), minimum end-diastolic minimum velocity (Vmin), peak systolic maximum velocity (Vmax), pulsatility index (PI), and resistance index (RI) values of the TSA and FA were measured and compared before and after pharmacological treatment. The relationship between the masseter muscle thickness and the Ved and Vmin values of the TSA and FA before and after pharmacological treatment was analyzed using the paired sample t test; the relationship between the temporal muscle thickness, TMJ spaces, and Vmax, PI, and RI values of the TSA and FA was analyzed using the Wilcoxon signed-rank test (α=.05).

RESULTS

A significant difference was found between the right temporal muscle thickness before and after medication (P=.01), whereas no statistically significant difference was found in the left temporal muscle thickness (P>.05). A significant difference was found between pretreatment and posttreatment bilateral masseter thicknesses at rest (right P=.014; left P=.004). No statistically significant difference was found in the bilateral joint space or Vmax, Vmin, Ved, PI, and RI values of the TSA and FA before and after treatment (P>.05).

CONCLUSIONS

Pharmacological treatment in participants with acute TMD led to a reduction in masseter and temporal muscle thickness but did not significantly affect joint space and local blood flow. USG is a useful diagnostic tool in the diagnosis and follow-up of TMDs.

Investigation of masticatory muscle thickness and mechanosensitivity of cervical and masticatory muscles in myofascial temporomandibular disorder patients with bruxism: A cross-sectional study

OBJECTIVE

Bruxism is a common problem associated with temporomandibular disorders (TMD). The aim of this study was to compare a patient group with Myofascial TMD and bruxism and a healthy control group in terms of masseter and temporal muscle thickness (clenching and resting), mechanosensitivity of neck and jaw muscles, craniofacial pain, and disability and emotional stress status.

METHODS

The study included 31 patients with myofascial TMD and bruxism (19 females, 12 males) with a mean age of 29.96 ± 8.12 years (range, 18-45 years), and a control group of 31 healthy subjects (19 females, 12 males) with a mean age of 27.58 ± 9.39 years years (range, 18-45 years). Masseter and temporal muscle thicknesses were evaluated with a mobile ultrasound device both at rest and when clenching the jaw. The mechanosensitivity values between the upper trapezius, obliquus capitis inferior, masseter and temporal muscles were measured with a digital algometer device. Craniofacial pain and disability level were evaluated with the Craniofacial Pain and Disability Index (CFPDI), and emotional stress levels with the Perceived Stress Scale-14 (PSS-14).

RESULTS

No difference was determined between the two groups in respect of the clenching and resting ratios of muscle thickness in any muscle (p > 0.05). The mechanosensitivity values in all muscles were lower in the myofascial TMD group than in the healthy group (p < 0.05). The CFPDI and PSS-14 scores were higher in the myofascial TMD group (p < 0.05). There was a moderate positive correlation between CFPDI, PSS-14 and Bruxism Frequency Score (p < 0.05).

CONCLUSION

The difference in mechanosensitivity and CFPDI values between the myofascial TMD patients with bruxism and the healthy control group indicates that the problem in this patient group has effects in the craniocervical and cervical regions. In addition, the correlation between CFPDI, PSS-14 and Bruxism Frequency Score in myofascial TMD patients suggests that this problem may be affected by the interaction of different parameters.

An investigation of the changes in mechanical properties of the orofacial and neck muscles between patients with myogenous and mixed temporomandibular disorders

OBJECTIVE

To investigate the possible changes in the mechanical properties of the orofacial and neck muscles in patients with temporomandibular disorders (TMD).

METHODS

The study included a total of 98 females. Females were divided into three groups as myogenous TMD, mixed TMD, and healthy controls. The frequency (indicator of muscle tone), stiffness, and decrement (related to muscle elasticity) values of the sternocleidomastoid, upper trapezius, cervical extensor, and masseter muscles were measured using a portable myotonometer.

RESULTS

The frequency, stiffness, and decrement values of the masseter muscle were higher in the mixed and myogenous TMD groups than those of the control group (p < 0.017). The mixed TMD group had higher frequency and stiffness values in the upper trapezius muscle compared with the control group (p < 0.017).

DISCUSSION

The results suggest that the mechanical properties of the oral and neck muscles may be affected in patients with TMD.

Quantitative and qualitative evaluation of the masseter muscle by ultrasonography and correlation with whole body health status

[Purpose] Ultrasonography can be used to non-invasively analyze any cross-section of the human body and to measure tissue elasticity, thickness, and brightness. This study was performed to examine the quantitative and qualitative changes in the masseter muscle at rest and at maximal occlusion, and to evaluate the relationship between these changes and the general health of the individual. [Participants and Methods] The study cohort comprised 30 healthy adults. Correlations between basic participant information (sex, age, height, body weight, body mass index, body fat, maximum bite force, handgrip strength, and tongue pressure) and masseter muscle ultrasonographic data were examined. [Results] Masseter muscle thickness was significantly greater in males than in females. Body weight and body mass index correlated positively with masseter muscle thickness. Body mass index and body fat percentage correlated positively with masseter muscle brightness. Tongue pressure correlated positively with handgrip strength. [Conclusion] Our analyses of muscle thickness and brightness suggest that ultrasonography may be useful in evaluating masseter muscle quantity and quality, and that the condition of the masseter muscle may correlate with the overall health status of the individual.

Determination of masseter and temporal muscle thickness by ultrasound and muscle hardness by shear wave elastography in healthy adults as reference values

OBJECTIVES

The purpose of this study is to prospectively investigate the reference values of masseter and temporal muscle thicknesses by ultrasonography and muscle hardness values by shear wave elastography in healthy adults.

METHODS

The sample of the study consisted of a total of 160 healthy individuals aged between 18 and 59, including 80 women and 80 men. By examining the right and left sides of each participant, thickness and hardness values were obtained for 320 masseter muscles and 320 temporal muscles in total.

RESULTS

The mean masseter muscle thickness was found to be 1.09 cm at rest and 1.40 cm in contraction. The mean temporal muscle thickness was found to be 0.88 cm at rest and 0.98 cm in contraction. The thickness values of the masseter and temporal muscles were significantly greater in the male participants than in the female participants (P < .001). While there were significant differences between the right and left masseter muscle thickness values at rest and in contraction, the values of the temporal muscles did not show a significant difference between the sides. While the resting hardness (rSWE) of the masseter muscle was transversally 6.91 kPa and longitudinally 8.49 kPa, these values in contraction (cSWE) were found, respectively, 31.40 and 35.65 kPa. The median temporal muscle hardness values were 8.84 kPa at rest and 20.43 kPa in contraction. Masseter and temporal muscle hardness values at rest and in contraction were significantly higher among the male participants compared to the female participants (P < .001).

CONCLUSION

In this study, reference values for the thickness and hardness of the masseter and temporal muscles are reported. Knowing these values will make it easier to assess pain in the masseter and temporal muscles and determine the diagnosis and prognosis of masticatory muscle pathologies by allowing the morphological and functional assessments of these muscles, and it will identify ranges for reference parameters.

Analysis of Cervical Range of Motion in Subjects Affected by Temporomandibular Disorders: A Controlled Study

Background and Objectives: The aim of this study were to compare the cervical ROM data obtained from accelerometer exams between patients suffering from TMDs (study group) and healthy patients (control group). Material and Methods: A sample of 43 young adult subjects (23 control subjects and 20 TMD patients) were included in this study and analyzed with the accelerometer (Baiobit™, BTS, Garbagnate Milanese, Milan, Italy) to assess cervical ROM using a standardized protocol, including the following occlusal conditions: mandibular rest position, clenching, clenching with cotton rolls, maximal intercuspation, and mandibular position with cotton rolls. The cervical ROM was measured in degrees and expressed as the mean and standard deviation. Results: TMD patients showed a reduced cervical extension compared to control subjects in all the conditions, with statistically significant relevance. Regarding the other movements, the differences were not statistically or clinically significant. Conclusions: Based on the results of the present study, it can be observed that temporomandibular disorders are associated with a decreased cervical extension range, while the remaining components of ROM do not seem to be significantly associated. The use of accelerometers in ROM analysis could be helpful in improving interdisciplinary communication between dentists and physiotherapists.

Electromyography: Processing, Muscles' Electric Signal Analysis, and Use in Myofunctional Orthodontics

Electromyography, commonly known as EMG, utilizes superficial or needle electrodes to record and analyze the fundamental electrical characteristics of skeletal muscles, determining whether the muscles are contracting. The motor unit, which consists of a collection of group muscle fibers and the motor neurons that govern them, is the structural basis of EMG. Three types of electrode are used in EMG which are needle electrode, fine wire electrode, and surface electrode. A significant amount of literature indicates that the correction of muscle function affects the relationships between teeth within the same jaw and between the jaws on opposing sides. The mechanism of action in myofunctional appliance therapy is linked to neuromuscular and skeletal adaptations resulting from altered function in the orofacial region. Both myofunctional therapy and orthodontics aim to address abnormal muscular behavior, restore abnormal muscle activity, and maintain proper alignment in various areas, including the lips, lower jaw, and tongue. This knowledge is essential for functions such as swallowing, speaking, chewing, and respiration as well as for minimizing incorrect movements and positioning. This article aims to describe the application of surface EMG as a diagnosis tool for assessing muscle activities in various orthodontic disorders, such as class II malocclusion open bite, crossbite, maxillary constriction, cleft lip and palate (CLP), and temporomandibular dysfunction, in patients. The electrodes used in EMG can be utilized to detect bioelectric activity in the muscles of the jaws and abnormalities in jaw movement. Analyzing EMG data is vital for obtaining a comprehensive understanding of the masticatory muscle system.

[Effect of the forward head syndrome in the development of temporomandibular disorders]

Bad habits, such as poor posture during the use of technological devices, poor abdominal control and oral breathing pattern can lead to a forward head position, which has important implications for the entire future of the individual, especially at the stomatognathic system. There is a strong association between temporomandibular disorders and forward head syndrome. Where the muscular component is the main affected, with the appearance of more trigger points at the level of the sternocleidomastoid muscles, upper trapezius, rectus capitis posterior and upper oblique capitis. Degenerative changes in the temporomandibular joint have been observed, but evidence is still lacking to ensure that Forward Head Syndrome is the etiological factor.

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.

Ultrasonographic and electromyographic evaluation of three types of occlusal splints on masticatory muscle activity, thickness, and length in patients with bruxism

OBJECTIVE

To evaluate occlusal splint type differences in patients with bruxism.

METHODS

Seventeen controls and 51 patients were divided into three subgroups, each assigned to use a different occlusal splint (hard, soft, or semi-soft) for 3 months and assessed by ultrasonography and electromyography (EMG) before (BT) and 3 months after treatment (AT).

RESULTS

EMG values in all of the occlusal splint groups were significantly lower AT than BT (p < 0.05). BT and AT EMG values in the control group did not differ. Mean muscle thicknesses in bruxism patients was greater than in controls, and the greatest muscle thickness changes occurred with the hard occlusal splint (p < 0.05).

DISCUSSION

A decrease in EMG activity occurred with all three splint types and was most prominent in the hard occlusal splint group. Ultrasonographic measurements of muscle length and thickness should be used alongside EMG to measure muscle activity in bruxism patients.

The Difference in Electromyographic Activity While Wearing a Medical Mask in Women with and without Temporomandibular Disorders

Wearing a medical mask influences resting activity of the temporalis anterior and masseter muscles in healthy young women. However, no studies link medical mask-wearing with masticatory muscle activity in patients with temporomandibular disorders (TMDs). Therefore, this study aims to compare electromyographic patterns while wearing a medical mask between women with and without temporomandibular disorders. Based on the Research Diagnostic Criteria for Temporomandibular Disorders, 115 adult women qualified for the study. Participants were divided into the following two groups: diagnosed TMDs (n = 55; mean age: 23.5 ± 2.3 years) and healthy women (n = 60; mean age: 23.7 ± 2.6 years). Examinations of the resting and functional electromyographic activity of the temporalis anterior (TA), superficial masseter (MM), anterior bellies of the digastric muscle (DA), and the middle part of the sternocleidomastoid muscle (SCM) were carried out using the BioEMG III™. Both groups showed statistically significant decreases in resting masticatory muscle activity during medical mask examination compared to no mask measurement. The significant differences in no mask measurement between both groups were noted regarding resting masticatory activity, clenching in the intercuspal position, and clenching on dental cotton rollers. During medical mask examination, women with TMDs showed differences in resting masticatory activity and clenching on dental cotton rollers compared to the healthy group. In all analyzed variables, both groups showed similar electromyographic patterns in the maximum mouth opening measurement during medical mask and no mask examination. A medical mask influences the resting bioelectric activity of the masticatory muscles in women with temporomandibular disorders and healthy women. We observed differences and some similarities in resting and functional electromyographic patterns within masticatory and neck muscles in both groups during medical mask and no mask examination.

Masticatory Muscle Thickness and Activity Correlates to Eyeball Length, Intraocular Pressure, Retinal and Choroidal Thickness in Healthy Women versus Women with Myopia

This study aims to examine the correlations between masticatory and neck muscle thickness and activity versus eyeball length, retinal thickness, choroidal thickness, and intraocular pressure in healthy women versus women with myopia. The study group consisted of 21 women aged 24 years and a control group of 19 women (mean age 23 years). For bioelectrical activity analysis within the temporalis anterior, the superficial part of the masseter muscle, the middle part of the sternocleidomastoid muscle, and the anterior belly of the digastric muscle, an eight-channel BioEMG III electromyograph were used. An M-Turbo ultrasound machine was used to analyze masticatory and neck muscle thickness. The eyeball length was examined by IOL Master 500; choroidal and retinal thickness by Optovue Angiovue; and intraocular pressure by Tono-Pen XL. Refractive errors are related to differences in muscle thickness and electromyographic activity. Bioelectrical activity within the temporalis anterior seems to be associated with ocular length, retinal thickness, and choroidal thickness in women with myopia.

Test-Retest Reliability of Ultrasonographic Measurements from the Rectus Femoris Muscle 1-5 Years after Anterior Cruciate Ligament Reconstruction in the Ipsilateral and Contralateral Legs: An Observational, Case-Control Study

About 40% of traumatic injuries in sports are related to the knee. Of these, 33% require arthroscopic surgery. The rehabilitative ultrasound imaging technique is a simple method to obtain objective real-time results on the state and measurement of the musculoskeletal tissue and its use can represent an important change in the process of functional diagnosis and recovery of these injuries. The aim was to quantify the differences in the thickness, muscle contraction time, and muscle relaxation time of the rectus femoris muscle between individuals with knee arthroscopy and healthy individuals and to verify the reliability of the inter-examiner measurements in these ultrasound variables. An observational case-control study with individuals (18−60 years aged) who underwent surgery for anterior cruciate ligament through knee arthroscopy a year or more before. A total of 38 subjects were divided into 2 groups, case and control. Ultrasound measurements were taken of the following outcomes: thickness at rest and contraction, muscle contraction time, and muscle relaxation time of the rectus femoris muscle. Excellent inter-examiner reliability was obtained for all ultrasound measurements (ICC3.3 > 0.90). No significant changes were found in the rate of contraction or rest of the rectus femoris muscle. On the other hand, if significant changes in the thickness of the rectus femoris muscle were found between control and case group. Arthroscopic surgery for anterior cruciate ligament reconstruction does not appear to modify function but does modify the thickness of the rectus femoris muscle on ultrasound examination. Ultrasound appears to be a reliable tool for the study of these measurements in the rectus femoris muscle.

The correlation between scapulocostal syndrome and masticatory myofascial pain on selected pain and functional parameters- an observational study

OBJECTIVES

Although scapulocostal syndrome (SCS) and masticatory myofascial pain (MMP) occur in different regions, the concept of myofascial linkage and neurophysiology may be proven per the connection of the two disorders. Therefore, this study aimed to investigate the correlation between SCS and MMP on selected pain and functional parameters.

METHOD

75 participants with SCS participated in the protocol. The diagnosis of SCS was considered by the presence of muscle referred pain in the medial scapular muscles. All participants were measured for pain intensity, pressure pain threshold (PPT), and craniovertebral angle (CV-angle) for pain and functional parameters related to SCS. They were measured for pain intensity, PPT, and mouth distance for the pain and functional parameters related to MMP. The diagnosis of MMP was considered by the presence of muscle tenderness of the masticatory muscle and the decreasing of mouth opening distance. The correlation between SCS and MMP was determined using Pearson's correlation coefficient and Spearman's correlation.

RESULTS

Participants exhibiting SCS were diagnosed for MMP at 74.67%. The results showed positive correlations in pain intensity and PPT between SCS and MMP (r = 0.367, r = 0.478, p < 0.01), PPT of SCS, and mouth distance amid both pain-free and maximum mouth opening conditions, respectively (r = 0.290, r = 0.282, p < 0.05).

CONCLUSION

In conclusion, SCS and MMP present an association with each other in terms of both selected pain, and functional parameters. Thus, a treatment program for SCS patients should be concerned with the masticatory muscles even if they did not report any pain at the jaw area.

Assessments of Muscle Thickness and Tonicity of the Masseter and Sternocleidomastoid Muscles and Maximum Mouth Opening in Patients with Temporomandibular Disorder

The purpose of this study was to compare the muscle thickness and tone of the masseter and sternocleidomastoid (SCM) muscles and maximum mouth opening (MMO) in subjects with and without temporomandibular disorders (TMD), and perform a correlation comparison on the results of the TMD group. Sixty patients were allocated to the TMD group (n = 30) or the non-TMD group (n = 30). Ultrasound imaging, myotonometer, and vernier calipers were used to determine the related changes in muscle thickness and muscle tone in masseter and SCM, and MMO, respectively. The TMD group revealed a significant decrease than the non-TMD group in the muscle thickness of masseter and SCM, respectively (p < 0.001), with a significant increase in frequency (p < 0.001) and stiffness (p < 0.001) in the masseter muscle tone, with a significant increase in frequency (p < 0.001) and stiffness (p = 0.005) in the SCM muscle tone, a significant decrease in the MMO (p < 0.001). There was a moderate negative correlation between the relaxed state of masseter muscle thickness and stiffness of SCM muscle tone (r = −0.40, p = 0.002), and a moderate negative correlation between the relaxed state of SCM muscle thickness and frequency of SCM muscle tone (r = −0.42, p = 0.001). There was a moderate negative correlation between the clenching state of SCM muscle thickness and the frequency of SCM muscle tone (r = −0.47, p < 0.001). In addition, a moderate negative correlation between MMO and frequency of SCM muscle tone (r = −0.44, p < 0.001). The muscle thickness was decreased, and the muscle tone was increased in the masseter and SCM muscle, respectively. Additionally, MMO was decreased in patients with TMD compared with non-TMD.

Electromyographic changes in masseter and sternocleidomastoid muscles can be applied to diagnose of temporomandibular disorders: An observational study

Background

The diagnosis of temporomandibular disorders (TMDs) is an important part of the functional cerebrospinal technique (FCST). In addition, surface electromyography (sEMG) is an important candidate for diagnosing TMD. In FCST, despite the importance of the cranio-cervical-mandibular system, few sEMG parameters consider TMDs. Thus, this study evaluated the possibility of TMD diagnosis by sEMG.

Methods

The study was conducted as an assessor-blinded cross-sectional study. Each of 35 participants were recruited for patient group and normal group separately based on the Diagnostic Criteria for TMD Symptoms Questionnaire (DC/TMD SQ). The sEMG was measured by attaching electrodes to sternocleidomastoid muscles (SCMM) and masseter muscles (MM) before and after wearing the temporomandibular joint balance appliance (TBA).

Results

The percentage overlapping coefficient (POC) value of the healthy control group was increased compared with the TMD group. Receiver operating characteristic (ROC) analysis revealed that the area under the curve (AUC) value of the SCMM was greater than that of the MM. POC values before and after the SCMM also revealed significant changes compared to the MM.

Conclusion

This study showed that the sEMG measurement of the SCMM is useful for TMD diagnosis in traditional Korean medicine.

Is jaw muscle activity impaired in adults with persistent temporomandibular disorders? A systematic review and meta-analysis

Understanding jaw muscle activity changes in temporomandibular disorders (TMD) is crucial to guide clinical management. The nature of these changes is currently unclear. Explore changes in jaw muscle activity in TMD. Electronic databases (PubMed, EMBASE, CINAHL, Scopus, Web of Science, Cochrane) and bibliographies were searched from inception to 9 July 2020 for eligible studies, including grey literature. Case-control and interventional studies reporting time-domain and frequency-domain electromyographic measures of jaw muscle activity in TMD and control groups were included. SIGN checklist for case-control studies was used to evaluate risk of bias. Results were pooled for meta-analysis using random-effects model. Confidence in cumulative evidence was established using American Academy of Neurology guidelines. Forty-five studies were included. Most were rated moderate risk of bias. Activity of four muscles (masseter, temporalis, lateral pterygoid, suprahyoids) was assessed across six domains (resting, clenching, chewing, swallowing, concentrating, resisted mandibular movements), with partial meta-analysis scope. Masseter and temporalis activity were significantly higher at rest (P = .05, P < .0001), but lower during brief maximal clenching (P = .005, P = .04) in TMD vs controls. Insufficient data precluded meta-analysis of remaining outcomes and subgroup analysis. Confidence in cumulative evidence ranged from moderate to very low. Changes in jaw muscle activity exist in TMD, which are both task-specific and muscle-specific. It remains unclear whether jaw muscle activity changes vary between TMD subgroups. Muscle function should be considered in clinical management of TMD. Insufficient subgroup data highlight future direction for research.

Short-Term Morphological Changes in Asymptomatic Perimandibular Muscles after Dry Needling Assessed with Rehabilitative Ultrasound Imaging: A Proof-of-Concept Study

Facial anatomical structures are not easily accessible to manual palpation. The aim of our study is to objectively assess temporomandibular joint and perimandibular muscles dimensions by means of sonographic measurements before and after dry needling (DN) in asymptomatic subjects. Seventeen subjects participated in this before-after study with a within-subject control. After random allocation, one side of the face was used for the intervention and the contralateral as control. DN was performed on the temporal, masseter, and sternocleidomastoid muscles. Each subject was examined bilaterally before, immediately after, and one month after the intervention through Rehabilitative Ultrasound Imaging (RUSI) of the temporomandibular articular disc and the three target muscles. Maximum mouth opening was measured at baseline and at one month. After a single DN session, articular disc thickness significantly decreased; muscles’ thicknesses (except for temporal thickness) significantly decreased immediately and at follow-up on the treated side; no significant changes resulted for the control side. The maximum mouth opening increased from 4.77 mm to 4.86 mm. RUSI may be useful to assess the dimensions and thickness of the temporomandibular disc and muscles before and after an intervention. DN influences muscle morphology, and it has a positive influence on mouth opening in the short term.

Neck associated factors related to migraine in adolescents with painful temporomandibular disorders

OBJECTIVE

Migraine is a comorbidity of painful temporomandibular disorders (TMDs). Both migraine and painful TMD have associations with neck pain and head posture. The aim of this study was to clarify the role of neck pain and head posture on the association between migraine and painful TMD in adolescents.

MATERIALS AND METHOD

In total 314 adolescents were included: 235 adolescents with only painful TMD (pTMD) and 79 adolescents with painful TMD and migraine (TMDMIG). Adolescents were diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders and International Classification of Headache Disorders, 3rd edition. Head postures were identified using lateral cephalograms. Myofascial trigger points (TrPs) were evaluated in the temporalis, masseter, trapezius, sternocleidomastoid, sub-occipitalis, and splenius capitis muscles.

RESULTS

Multivariate logistic regression analysis confirmed the associations among the orofacial pain duration, number of active TrPs in the trapezius muscles, intensity of neck pain, and distance between the occiput and atlas and migraine in adolescents with TMD. The relationships among intensity of neck pain, number of TrPs in the cervical muscles, and head posture were more prominent in the TMDMIG than those in the pTMD.

CONCLUSION

Neck associated factors seemed to have relevance with migraine in adolescents with painful TMD.

Methods of Masseter and Temporal Muscle Thickness and Elasticity Measurements by Ultrasound Imaging: A Literature Review

BACKGROUND

The positive correlation between changes in the morphology of masseter and temporal muscles and some disorders, inclines diagnosticians to search for an effective method of assessing muscle thickness and elasticity. Ultrasound imaging, as a relatively simple and cheap method, seems to be a useful diagnostic tool.

OBJECTIVE

The aim of this study was to present the existing ultrasound imaging methods in the assessment of the elasticity and thickness of the masseter and temporal muscles.

METHODS

The literature review has been done with a focus on the accurate description of the masseter and/or temporal muscle examination by ultrasonography imaging methods. Articles were categorized into two groups. The first group included articles in which muscle thickness was assessed by ultrasound imaging. The second group concerned the elasticity aspect of mentioned muscles.

RESULTS

It is difficult to achieve an objective protocol of masseter and temporal thickness assessment by ultrasonography and there is no method that has been fully verified in terms of reliability. The shear-wave sonoelastography revealed higher-level reliability of masseter muscle elasticity than strain sonoelastography. During the shear-wave sonoelastography, the effect of scan plane in relation to masseter muscle pennation and the day-to-day variation were statistically significant. With regard to elasticity of temporal muscle, further research is needed.

CONCLUSION

This review has shown that there is a limited number of methods for masseter and temporal muscle thickness and elasticity measurements by ultrasonography. All procedures (methods) were not fully verified in terms of reliability and agreement. Thus, it is still necessary to develop standardized procures to assess thickness and elasticity of the masseter and temporal muscles with appropriate reliability and accuracy.

Manifestation of stress and anxiety in the stomatognathic system of undergraduate dentistry students

Objective

To assess the relationship between psychoemotional state and signs of oral cavity occlusal and nonocclusal parafunctions, together with masseter muscle tone, in undergraduate dentistry students.

Methods

The study population comprised first and fifth grade dentistry students who were investigated using psychological and health questionnaires, and stomatological examination with electromyography of the masseter muscles. Differences in variables between first and fifth grade students were analysed using Student’s t-test or χ²-test and Pearson’s correlation coefficient was used to analyse associations between variables.

Results

A total of 113 students (52 first-grade, mean age 20 years; and 61 fifth-grade, mean age 23.6 years) were included. Older age was associated with lower level of perceived stress and anxiety. Moreover, a significant positive relationship was observed between level of perceived stress and anxiety and tone of both masseter muscles.

Conclusions

Increased psychoemotional burden and increased rates of experienced anxiety were associated with growth of masseter muscle tone in this study population.

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.

Comparison of Ultrasonic Thickness of Masseter Muscle Between Individuals With and Without Severe Forward Head Posture: A Cross-Sectional Study

OBJECTIVE

In this cross-sectional descriptive-analytical study, we sought to compare the ultrasonic thickness of the masseter muscle in people with severe forward head posture vs people without forward head posture, and to determine sex differences in muscle thickness.

METHODS

Thirty-eight volunteers (19 with normal head postures and 19 with severe forward head postures), aged 18 to 35 years, entered the study. The severity of the forward head posture was measured by a plumb line and the craniovertebral angle drawn on the recorded images. Based on the recorded images, the masseter muscle thickness was also measured by a 7.5-MHz linear transducer using an ultrasound device in the seated position with 3 mouth positions (closed, half open, and fully open).

RESULTS

The results showed that the head posture affects masseter thickness significantly (P = .01), with masseter thickness significantly lower in the participants without severe forward head postures compared to those with severe forward head postures in the closed, half-open, and fully open mouth positions (P < .05). Comparing the mean masseter thickness across sexes showed that the masseter muscle is significantly thicker in men compared to women (P = .01).

CONCLUSION

Head posture and thickness of the masseter muscle are linked, as the masseter muscle was thicker in all 3 positions in the participants with severe forward head postures.

Current advances and research in ultrasound imaging to the assessment and management of musculoskeletal disorders

Currently evidence-based practice has given scientific weight to the physical therapist profession; it is essential that all medical professional and physical therapists know the usefulness of new tools that optimize the effectiveness of their interventions and allow the growing of the scientific knowledge base. The use of ultrasound imaging (USI) by physiotherapists has evolved in recent years, consolidating as an increasingly standardized technique, low cost compared to other imaging techniques, quickly of execution, feasible and reliable tool. USI offers a wide range of opportunities in clinical practice as well as in different research areas. Therefore, ultrasound has been currently used as a diagnostic tool by physicians and in recent years there has been an expansion of the use of ultrasound equipment by non-physicians professionals such as physical therapist or physical trainers, who incorporates USI as a means of assessing musculoskeletal system architecture and composition, musculoskeletal changes in dysfunction, pain or injury conditions, as an interventional technique assisting echo-guided procedures or using the visual real-time information as a biofeedback in control motor approaches, as guiding tool in clinical decisions as well as to improve the understanding of tissue adaptations to exercise or movement. The purpose of this article is to review and provide an overview about the currently research of the USI applications and their benefits for the diagnosis and management in individuals with musculoskeletal conditions.

Ultrasonography Comparison of the Plantar Fascia and Tibialis Anterior in People With and Without Lateral Ankle Sprain: A Case-Control Study

OBJECTIVE

The purpose of the present study was to evaluate the thickness of the plantar fascia (PF) at the insertion of the calcaneus and the midfoot and forefoot fascial locations, in addition to the thickness of the tibialis anterior, by ultrasound imaging in individuals with and without lateral ankle sprain (LAS).

METHODS

A sample of 44 participants was recruited and divided in 2 groups: 22 feet with a prior diagnosis of grade 1 or 2 LAS (case group) and 22 feet without this condition (healthy group). The thickness and cross-sectional area were evaluated by ultrasound imaging in both groups.

RESULTS

Ultrasound measurements of the PF at the calcaneus, midfoot, and forefoot showed statistically significant differences (P < .05), with a decrease in thickness in the LAS group relative to the healthy group. For the thickness and cross-sectional area of the tibialis anterior, no significant differences (P < .05) were observed between groups.

CONCLUSION

The thickness of the PF at the calcaneus, midfoot, and forefoot is reduced in individuals with LAS relative to the healthy group.

Cervical spine range of motion, posture and electromyographic activity of masticatory muscles in temporomandibular disorders

Abstract Introduction: Temporomandibular joint disorders (TMD or TMJD) involve clinical problems and symptoms affecting the temporomandibular joint (TMJ) and associated structures. The temporomandibular joints are anatomically connected to the cervical region, where cervical spine movements occur simultaneously to masticatory muscle activation and jaw movements. Objective: Our study sought to assess the relationship between the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), surface electromyography (sEMG) of the masticatory muscles, posture and cervical flexibility in women with TMD. Method: Fifty women with an average age of 27.0 ± 6.37 years, diagnosed with TMD according to RDC/TMD, were assessed for craniocervical posture, cervical flexibility and sEMG of the masticatory muscles. Results: There were no differences in jaw function limitations, depression, pain level and its interference in work ability and daily activities, posture and sEMG between TMD diagnoses or between muscle classification (p > 0.05). Depression scores were higher among participants with biarticular dysfunction (p = 0.023). The group with bruxism exhibited a higher pain level at assessment (p = 0.001) and a greater reduction in work ability (p = 0.039). Subjects with muscular and mixed TMD showed less cervical rotation to the right when compared with those with articular TMD. Conclusion: There was no difference in posture or sEMG values for TMD diagnoses, joint and muscle dysfunctions and the presence of bruxism. Muscle dysfunction is associated with reduced cervical rotation to the right. Jaw function limitations did not interfere in posture or sEMG and depression was associated with pain.

The association between Parkinson's disease and temporomandibular disorder

The prevalence of temporomandibular disorder (TMD) among elderly people with Parkinson’s disease (PD) is relatively high, but a population-based study of the relationship between PD and TMD is still lacking. This study, therefore, sought to investigate the association between TMD and PD by using data for one million randomly sampled beneficiaries of Taiwan’s National Health Insurance program, including 6,185 PD patients who were matched through propensity score matching with 18,555 non-PD patients. Both the PD and non-PD cohorts were followed until death, any diagnosis of TMD, or December 31, 2013, whichever occurred first. Each diagnosis of TMD was made by a qualified physician according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), using the diagnosis codes 524.60, 524.62, 524.63, and 524.69 while excluding tooth abscess, wisdom tooth eruption, herpes zoster and postherpetic neuralgia, mastoiditis, otitis externa, otitis media, parotitis, sialadenitis, and trigeminal neuralgia. We used Cox proportional hazard regression models to calculate the relative risk of TMD and found a 2.11-fold (95% CI: 1.35–3.30) increased risk of TMD overall in the PD group compared with the non-PD group. Stratified by follow-up period, there was a 4.25-fold (95% CI: 1.51–11.93) increased risk in the PD group in the first year after the initial PD diagnosis and a 3.88-fold (95% CI: 1.33–11.28) increased risk in the second year. Over the long-term (>5 years), PD was significantly associated with an increased risk of TMD. These findings suggest that it is important to closely monitor the temporomandibular joint health of PD patients.

Ultrasonography Features of the Plantar Fascia Complex in Patients with Chronic Non-Insertional Achilles Tendinopathy: A Case-Control Study

Purpose: The goal of the present study was to assess, by ultrasound imaging (USI), the thickness of the plantar fascia (PF) at the insertion of the calcaneus, mid and forefoot fascial locations, and the calcaneal fat pad (CFP) in patients with Achilles tendinopathy (AT). Methods: An observational case-control study. A total sample of 143 individuals from 18 to 55 years was evaluated by USI in the study. The sample was divided into two groups: A group composed of the chronic non-insertional AT (n = 71) and B group comprised by healthy subjects (n = 72). The PF thicknesses at insertion on the calcaneus, midfoot, rearfoot and CFP were evaluated by USI. Results: the CFP and PF at the calcaneus thickness showed statistically significant differences (P < 0.01) with a decrease for the tendinopathy group with respect to the control group. For the PF midfoot and forefoot thickness, no significant differences (P > 0.05) were observed between groups. Conclusion: The thickness of the PF at the insertion and the CPF is reduced in patients with AT measured by USI.

Ultrasound evaluation of extrinsic foot muscles in patients with chronic non-insertional Achilles tendinopathy: A case-control study

AIM

The purpose of the present study was to compare and quantify with ultrasound imaging (USI) the extensor digitorum longus (EDL), tibialis anterior (TA) and peroneus muscles (PER) muscle thickness and cross-sectional area (CSA) between chronic non-insertional Achilles tendinopathy (AT) and healthy subjects.

METHODS

a sample of 143 individuals was recruited and divided in two groups: chronic non-insertional AT group (n = 71) and a healthy group (n = 72). The thickness and CSA were assessment by USI for EDL, TA and PER muscles in both groups.

RESULTS

The thickness evaluation for the TA muscle increased showing statistically significant differences (P = 0.018) as well as for the thickness of the PER muscles significant differences (P = 0.001) were observed in favor the tendinopathy group. The CSA measurements showed statistically significant differences for a decrease in EDL (P = 0.000), TA (P = 0.001) and PER muscles (P = 0.011) for the tendinopathy group with respect to the control group.

CONCLUSIONS

The CSA of the EDL, TA and PER muscles is reduced in participants with chronic non-insertional AT. The thickness for TA muscle is increased as well as a decrease of PER muscles thickness is presented for the AT group with respect to the control group.

Temporal muscle thickness as a new indicator of nutritional status in older individuals

AIM

Temporal muscle wasting is subjectively evaluated during nutritional assessment of protein-energy malnutrition. However, a quantitative evaluation method has not been established. The aim was to verify the validity and reliability of temporal muscle thickness measurement in comparison with established indicators of nutritional status, such as body mass index.

METHODS

A cross-sectional study was carried out from September 2016 through June 2017. A total of 73 individuals aged ≥65 years were recruited from two facilities and one community walking group. Temporal muscle thickness was measured using ultrasonography. Nutritional status was assessed with anthropometric measurements and laboratory examinations.

RESULTS

For validity, the temporal muscle thickness showed strong correlations with muscle mass, including calf circumference (r = 0.608, P < 0.001) and arm muscle circumference (r = 0.433, P < 0.001). In contrast, no strong correlations were observed with serum protein levels, such as albumin (r = 0.324, P = 0.005), or fat mass evaluated as triceps skinfold thickness (r = 0.216, P = 0.067). Temporal muscle thickness was significantly related to body mass index after adjusting for possible confounding factors of masticatory status, age and sex (β = 0.335, P = 0.007). As for reliability, the intrarater reliability of the temporal muscle measurement was 0.99 (95% confidence interval 0.98-1.00). Bland-Altman plot analysis showed no systematic errors, and the coefficient of variation of temporal muscle thickness measurements was 2.3%.

CONCLUSIONS

The present study suggests that measuring a temporal muscle thickness using ultrasonography is a valid and reliable method for evaluating nutritional status. Geriatr Gerontol Int 2019; 19: 135-140.

Ultrasonography features of abdominal perimuscular connective tissue in elite and amateur basketball players: an observational study

SUMMARY The purpose of this study was to assess and compare with rehabilitative ultrasound imaging (RUSI) the perimuscular connective tissue (PMCT) and interrecti distance (IRD) between elite and amateur basketball players. A sample of 22 healthy basketball players was included and divided into two groups: elite basketball players from Spanish 1st division (n = 11) and amateur basketball players from an entertainment Spanish division (n = 11). Ultrasound images of the external oblique (EO), internal oblique (IO), transversus abdominis (TrAb), rectus anterior (RA) and IRD PMCT were measured and analysed by the ImageJ software. Measurements of abdominal wall muscles PMCT present statistically differences (P < .05) for an increase of perimuscular connective tissue of external oblique (PMCTEO), perimuscular connective tissue of transversus abdominis (PMCTTA) of the left side and an increase of PMCTEO on the right side in favor of the elite group. Rather, the study showed statistically differences (P < .05) for a decrease of perimuscular connective tissue between the internal oblique and transversus abdominis (PMCTIO-TA), and a decrease in PMCT total summation of the left side with elite group in respect to amateur group. This study reported an increase of left PMCTEO, left PMCTTAA, right PMCTEO as well as a decrease of left PMCTIO-TA and in PMCT total summation on the left side.

Ultrasonographic evaluation of jaw elevator muscles in young adults with bruxism and with and without attrition-type tooth wear: A pilot study

OBJECTIVE

This pilot study was planned to analyze masticatory activation in bruxism patients with and without attrition by ultrasonographic evaluation of mandibular adductor muscles.

METHODS

Sixty bruxism patients (group 1: 30 without attrition, group 2: 30 with attrition) and an age-sex matched control of 30 (group 3) were clinically examined. The thickness of bilateral temporalis and masseter muscles during clench and rest was measured by ultrasonography.

RESULTS

The mean muscle thicknesses were higher in bruxing patients than in controls. In group 2, the clench/rest ratio (C/R) of the right and left masseter and temporal muscles were higher than the control group (p = 0.03, p = 0.01, p = 0.04, p = 0.03, respectively).

CONCLUSION

The thickness of chewing muscles increases with bruxism. The occlusal forces in the teeth increase, and therefore, the tooth wear increases. Ultrasonographic muscle thickness can be used to determine muscle activity in bruxism patients.

Design and Evaluation of Smart Glasses for Food Intake and Physical Activity Classification

This study presents a series of protocols of designing and manufacturing a glasses-type wearable device that detects the patterns of temporalis muscle activities during food intake and other physical activities. We fabricated a 3D-printed frame of the glasses and a load cell-integrated printed circuit board (PCB) module inserted in both hinges of the frame. The module was used to acquire the force signals, and transmit them wirelessly. These procedures provide the system with higher mobility, which can be evaluated in practical wearing conditions such as walking and waggling. A performance of the classification is also evaluated by distinguishing the patterns of food intake from those physical activities. A series of algorithms were used to preprocess the signals, generate feature vectors, and recognize the patterns of several featured activities (chewing and winking), and other physical activities (sedentary rest, talking, and walking). The results showed that the average F1 score of the classification among the featured activities was 91.4%. We believe this approach can be potentially useful for automatic and objective monitoring of ingestive behaviors with higher accuracy as practical means to treat ingestive problems.

Influence of anthropometry, TMD, and sex on molar bite force in adolescents with and without orthodontic needs

PURPOSE

Bite force has been studied as representative of functional indices of mastication and its value may have diagnostic significance in disorders of the musculoskeletal system of facial bones. This study aimed to evaluate bite force in adolescents with and without orthodontic needs considering presence of temporomandibular disorders (TMD) as well as anthropometry: craniofacial dimensions and body mass index (BMI).

METHODS

A total of 80 subjects were screened (61 females, 19 males; 18 ± 3 years old). Unilateral molar bite force was measured using a digital dynamometer with a fork thickness of 12 mm. Direct anthropometry was used to quantify craniofacial measurements. Dental Health Component of the Index of Orthodontic Treatment Need (IOTN-DHC) and the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were used to classify samples according to malocclusion and to TMD, respectively. Data were analyzed using normality tests, Mann-Whitney U test, and multiple linear regression analyses with stepwise backward elimination, controlling for the presence of malocclusion and TMD (p ≤ 0.05).

RESULTS

The cephalic index was greater in females with malocclusion and the longitudinal cranial diameter was reduced in females with malocclusion. BMI was not different between normal and malocclusion groups for either gender. Bite force was negatively related with vertical dimension of the face, and positively related with facial width and facial index. The model explained 32% of bite force variability, considering the sample size (coefficient of determination R ² = 0.324).

CONCLUSIONS

Even when orthodontic needs and TMD signs and symptoms are present, stronger bite force is still observed in males and in subjects with smaller anterior facial heights and wider facial widths.

Masseter muscle measurement performed by ultrasound: a systematic review

The aim of this study was to systematically review the existing scientific literature and evidence about (a) the validation of masseter muscle ultrasonography for accurate assessment of muscle thickness and (b) the reproducibility of masseter muscle thickness measures. An electronic literature search was conducted using determined keywords on specific databases. Preliminary search revealed 298 articles listed in Medline, Scopus and Web of Science. 60 duplicates were rejected, leaving 238 articles for review. After reading titles and abstracts, 31 articles remained. 23 articles were assessed for eligibility. These articles were categorized as follows: thickness, cross-section, volume and the length of the masseter muscle measured by ultrasonography. It is possible to verify the thickness of the masseter muscle in males and females in relaxation (10-15 and 9-13 mm, respectively) and contraction (14-19 and 12-15 mm, respectively). A similar tendency can also be evidenced in other measurements. Many studies evaluate masseter muscle dimensions to relate it to cephalometric analysis as such to evaluate morphological variations. It can be concluded that ultrasound is a reliable clinical tool for masseter muscle measurements, yet there is a need for standardization of methods and parameters to be recorded.

Comparison of cervical muscle thickness between asymptomatic women with and without forward head posture

BACKGROUND

Forward head posture (FHP) is a forward positioning of the head relative to the trunk in the sagittal plane. This posture is one of the most prevalent poor postures in patients with head and neck pain. Rehabilitative Ultrasound Imaging (RUSI) is a reliable method to objectively evaluate muscle thickness and function.

OBJECTIVE

To compare thickness of cervical muscles that control both head and neck posture between asymptomatic women with and without FHP.

METHODS

Seventy asymptomatic women aged between 20 and 40 years, with and without FHP (35 in each group), participated in the study. The thickness of the cervical muscles (rectus capitis posterior - RCP, oblique capitis superior - OCS, semispinalis capitis - SSC, sternocleidomastoid - SCM, and longus coli - LCo) was measured using RUSI and the data was compared between the two groups.

RESULTS

The comparison of cervical muscle thickness between women with and without FHP revealed significant difference only with regard to the muscle thickness of the SCM muscle (mean difference: 0.7mm, 95% confidence interval of the difference: 0.14, 1.26mm, p value: 0.014). The thickness of this muscle was greater in women with FHP.

CONCLUSION

Tonic contraction of the SCM muscle can lead to greater thickness of this muscle in subjects with FHP.

Magnetic resonance and sonographic imagings of masticatory muscle myalgia in temporomandibular disorder patients

This article reviews recently published studies investigating the MRI and sonographic diagnosis of masticatory muscle myalgia in temporomandibular disorder patients. The MRI and sonographic features of muscle after treatment are also discussed. Literature published within the last 15 years was obtained from the PubMed database using the following Mesh terms: magnetic resonance imaging (MRI) or sonography, masticatory muscle pain, and treatment. MRI and sonography enable accurate visualization and evaluation of the masticatory muscles, thereby increasing our understanding of pathology and cause of pain associated with these muscles. Although therapeutic efficacy is often evaluated based on clinical findings, MR and sonographic imaging studies may also be valuable.

A glasses-type wearable device for monitoring the patterns of food intake and facial activity

Here we present a new method for automatic and objective monitoring of ingestive behaviors in comparison with other facial activities through load cells embedded in a pair of glasses, named GlasSense. Typically, activated by subtle contraction and relaxation of a temporalis muscle, there is a cyclic movement of the temporomandibular joint during mastication. However, such muscular signals are, in general, too weak to sense without amplification or an electromyographic analysis. To detect these oscillatory facial signals without any use of obtrusive device, we incorporated a load cell into each hinge which was used as a lever mechanism on both sides of the glasses. Thus, the signal measured at the load cells can detect the force amplified mechanically by the hinge. We demonstrated a proof-of-concept validation of the amplification by differentiating the force signals between the hinge and the temple. A pattern recognition was applied to extract statistical features and classify featured behavioral patterns, such as natural head movement, chewing, talking, and wink. The overall results showed that the average F1 score of the classification was about 94.0% and the accuracy above 89%. We believe this approach will be helpful for designing a non-intrusive and un-obtrusive eyewear-based ingestive behavior monitoring system.

Masticatory efficiency and muscular activity in removable partial dental prostheses with different cusp angles

STATEMENT OF PROBLEM

The loss of posterior teeth has a negative effect on the masticatory efficiency and activity of mastication muscles. How these muscles are affected by partial removable dental prostheses (PRDPs) with different cusp angles is unknown.

PURPOSE

The purpose of this clinical study was to evaluate the influence of different cusp angles, with anatomic (33 degrees), semianatomic (20 degrees), and nonanatomic teeth (0 degree), on the masticatory efficiency and muscular activity of participants receiving mandibular bilateral distal PRDPs.

MATERIAL AND METHODS

Fifteen participants consented to the evaluation of masticatory efficiency and electromyographic (EMG) activity with a PRDP with a unified bilateral design. The cusp angles of the artificial teeth were randomly changed from anatomic (33 degrees), semianatomic (20 degrees), and nonanatomic teeth (0 degree). Masticatory efficiency was evaluated by recording 5 parameters, including number of strokes, and time of mastication while the EMG activities of the masseter and temporalis muscles, measured using surface electromyography. The data were analyzed with 1-way ANOVA and the Tukey multiple post hoc test with statistical software (α=.05).

RESULTS

With regard to masticatory efficiency, PRDPs with anatomic and semianatomic teeth exhibited higher masticatory efficiency than those with nonanatomic teeth, whereas no significant differences were found between PRDPs with anatomic and semianatomic teeth. With respect to EMG activity, the least EMG activity was observed in PRDPs with anatomic teeth, whereas the highest activity was observed with nonanatomic teeth. No significant differences were found between the effect of PRDPs with anatomic and semianatomic teeth on masseter activity.

CONCLUSIONS

Changing the cusp angle from 33 to 20 degrees in PRDPs did not influence the masticatory efficiency or the EMG activity of the masseters. However, it did lead to increased EMG activities of the temporalis muscle. PRDPs with nonanatomic teeth were associated with a significant decrease in masticatory efficiency accompanied by a significant increase in EMG activity.

Cervical-scapular muscles strength and severity of temporomandibular disorder in women with mechanical neck pain

Abstract Introduction: Changes in cervical muscle function have been observed in patients with neck pain (NP) and TMD. However, the relationship between TMD severity and neck muscle strength in the presence/absence of NP is unknown. Objective: To determine the prevalence of TMD in women with and without mechanical NP and assess the cervical-scapular muscle strength and its association with TMD severity. Methods: Fifteen volunteers without neck pain (CG) and 14 women with mechanical neck pain (NPG) took part and were selected by the Neck Disability Index. The diagnosis and severity of TMD were determined by the Research Diagnostic Criteria for TMD and Temporomandibular Index (TI), respectively. The strength of the upper trapezius muscle, and cervical flexor and extensor muscles was measured by digital hand dynamometer. Results: 64.5% of women with NP and 33.3% without NP were diagnosed with TMD (p = 0.095). The NPG showed lower strength of the cervical flexor (p = 0.044) and extensor (p=0.006) muscles, and higher TI (p = 0.038) than in the CG. It was also verified moderate negative correlation between TI and the strength of dominant (p = 0.046, r = -0.547) and non-dominant (p = 0.007, r = -0.695) upper trapezius, and cervical flexors (p = 0.023, r = -0.606) in the NPG. Conclusion: There was no difference in the prevalence of TMD in women with and without NP. However, women with NP have lower cervical muscle strength - compared to those without NP - which was associated with greater severity of TMD. Thus, in women with NP associated with TMD, it is advisable to assess and address the severity of this dysfunction and identify the cervical-scapular muscles compromise.