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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.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.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).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.

The masseter muscle changes remarkably with orthognathic surgery and has a marked influence on the contours of the lower face. If the postoperative volume change of masticatory muscles, including the masseter muscles, can be predicted, it will facilitate preoperative planning and outcome prediction. This study investigated the association of masticatory muscle volume according to the presence or absence of facial asymmetry, and evaluated whether the volume of masticatory muscles, including that of the masseter muscle, changes after orthognathic surgery in facial asymmetry patients.Twenty patients who underwent LeFort I osteotomy and bilateral sagittal segmentation ramus osteotomy (BSSRO) with facial asymmetry between 2011 and 2017 were assigned to the asymmetric group. Additionally, 207 patients with a simple nasal fracture between 2016 and 2019 were included as the common group. Three-dimensional computed tomography images were retrospectively analyzed and compared between the asymmetric group and common group.The volume of both temporal and masseter muscles differed according to facial asymmetry, with the asymmetry in the muscle volume increasing in proportion to the degree of facial asymmetry. The difference in masseter volume on the shortened and lengthened sides was significantly reduced after orthognathic surgery, but a difference of about 1 cm3 remained. Additionally, the masticatory muscle volume on the lengthened side tended to be decreased more than that on the shortened side.Consideration of the postoperative change in the volume of the masticatory muscles may be helpful in planning orthognathic surgery in facial asymmetry patients.

Made available in DSpace on 2022-05-01T10:02:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Background: Temporomandibular disorders (TMDs) are treated by different modalities including splints, physiotherapy, and acupuncture. Although all of these offer evidencebased benefits to the patients, avoiding overtreatment is of paramount importance. Objectives: To assess the effectiveness of muscle pain treatment with acupuncture combined with or without occlusal splints. Methods: Recruited patients were allocated to G1 (acupuncture) and G2 (acupuncture and occlusal splint) groups and treated in four consecutive weekly sessions (P1, P2, P3, and P4). The reported pain (RP) and the pressure pain threshold (PPT) of the masseter and temporalis muscles were assessed before and after each session. Results: RP decreased after each session in G1, except at P4. In G2, the RP decreased only after the first session, and the PPT did not vary. Conclusion: The assessed treatments did not influence the PPT levels of the masseter and anterior temporalis muscles in patients with temporomandibular disorders. Our findings suggest that occlusal splints may not be mandatory along with the acupuncture treatment Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) School of Dentistry Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) School of Dentistry

Objectives: To examine the relationship between masticatory muscle activity (MMA), self-reported oral behaviours (OBs) and overall physical activity (PA) in adult women. Materials and methods: MMA and PA were assessed by a wearable electromyography (EMG) device and accelerometer respectively, worn over 2 non-consecutive days by 53 women (mean age 27.5 ± 6.4 years). Following the second recording day, self-reported OBs were assessed. MMA was assessed by the number, amplitude and duration of masseter contraction episodes. Masseter muscle EMG outcome measures were number of contraction episodes per hour (CEs/h) and the relative contraction time (RCT%). PA was assessed by time accumulated in moderate to vigorous physical activity (MVPA) and 10-min bouts of MVPA per hour. Data were analysed using mixed model analysis. Results: MMA in free-living conditions consisted mostly of low-amplitude (

Aim: The aim of our study was to investigate features related to EMG-activity of masticatory muscles in subjects with TMD. materials and methods: The study comprised 22 patients with clinical symptoms of TMD. The average age of the subjects was 29.3 ± 4.4 years. Malocclusion was evaluated according to Angle classification, TMD – according to the Research Diagnostic Criteria (RDC/TMD). Registration of EMG-activity of masseter and anterior temporalis muscles was performed during maximum voluntary clenching, clenching on the right and left sides. Results: Normal activity of the masticatory muscles is characterized by symmetrical and EMG-activity of the masticatory muscles on the left and right sides. EMG-activity of masticatory muscles in subjects with TMD are characterized by: 1) increased values of EMG-activity of temporal and masseter muscles; 2) disproportional and asymmetric muscle work of the masticatory muscles on the right and left sides. Conclusions: Features of masticatory muscles activity in individuals with Angle Class I malocclusion and TMD were found.

Background: The diagnosis of sleep bruxism (SB) in children is difficult due to the lack of a polysomnographic protocol for this population. Moreover, the gold standard treatment [occlusal splint (...

Background: Electromyographic (EMG) activities of single implant-retained mandibular overdentures (MODs) has been dubious. Midline fracture of the denture is the most common complication related to Single implant-retained MODs. Thermoplastic polymethylmethacrylate (PMMA) acrylic resin achieves even distribution of forces and helps in absorption of impact forces which occurs during functional and parafunctional activities. Aim of the study: This clinical study aimed to investigate whether thermoplastic PMMA can improve the EMG activity and decrease the incidence of denture fracture in single implant- retained MODs. Materials and Methods: A randomized controlled trial was designed, where 28 completely edentulous patients (15 male, 13 female) were enrolled and randomly divided into two equal groups. Group I (control group) received single implant- retained MOD fabricated from conventional PMMA and group II received a single implant- retained MOD fabricated from thermoplastic PMMA acrylic resin. Patients’ muscle activity was evaluated at baseline and at 3, 6 and 12 months using EMG. The survival rate of MOD was evaluated by recording the incidence of mid-line fractures. Results: There was a significant improvement in the EMG activity of the masseter and temporalis muscle of the thermoplastic PMMA group in all the follow-up periods. There was a non-statistically significant difference in the MOD survival between groups. However, the decrease in fracture incidence was clinically significant in the thermoplastic PMMA acrylic MOD group. Conclusion: Within the limitation of this study, it was concluded that the fabrication of single implant-retained MODs from thermoplastic PMMA acrylic resins improves masticatory muscle activity and overdenture survival.

This study aimed to analyze the effect of wearing a mouthguard or not on masticatory muscle tone and stiffness of male taekwondo athletes during high-intensity weight training. The participants were male taekwondo athletes and aged 18 to 22 years. We randomly divided 24 men into the control group (CON; without a mouthguard; n=12) and the experimental group (MOG; with a mouthguard; n=12). Masticatory muscle tone and stiffness were measured after weight training at a level of 70% of one-repetition maximum. As a result of this study, masticatory muscle tone was no different in intragroup and intergroup after experiment. In addition, although the masticatory muscle stiffness was significantly higher in the dominant side of the MOG, there was no difference in intergroup, intragroup, and interaction. Through this study, it is necessary to consider the selective wearing of a mouthguard according to the training methods when partially analyzed from the physiological point of view of the masticatory muscle of taekwondo athletes.

Aim: The present study was done to compare the muscle thickness of the masseter and anterior temporalis muscle in adults with normal occlusion and anterior open bite using ultrasonography, in rest position and maximum intercuspation. Material and Methods: Ultrasonographic recording of masseter and anterior temporalis thickness of both sides of nine subjects with anterior open bite and normal occlusion was done. Unpaired t test was used for the intergroup comparison of muscle thickness. Results: A significant correlation between the thicknesses of both the muscles in contracted state was found to be more in anterior open bite. There was no statistically significant correlation between thicknesses of both muscles in relaxed state. Conclusion: Since no detailed investigation was done, it will be premature to give a final verdict on the correlation between the masticatory muscle thickness and facial morphology. A long term follow up will provide a new insight for future clinical purpose. Keywords: Ultrasonography, Temporalis muscle, Masseter, Open bite.

Objective This study investigated the first night effect on the polysomnographic diagnosis of sleep bruxism (SB). Methods Polysomnographic recordings were performed for two consecutive nights in forty-three subjects (mean age 23.7 ± 0.32 years [range: 20.0–33.0]). Sleep variables and rhythmic masticatory muscle activity (RMMA) were scored for two nights. The diagnosis of SB was graded by the frequency of RMMA with cut-off values of two and four times per hour of sleep. Results Participants were classified into control (n = 15), low (n = 13) and moderate-high (n = 15) groups. Among the three groups, the concordance of the SB diagnosis was compared between the two nights. Sleep variables showed a significant first-night effect with lower sleep efficiency, longer sleep latency and higher frequency of arousals. The frequency of RMMA significantly increased from the first to the second night in the moderate-high SB group only. The concordance rate of the severity between the two nights was 93.3% (14/15) in the control group, 76.9% (10/13) in the low SB group and 60% (9/15) in the moderate-high SB group. When the severity was determined on the first night, it remained the same on the second night in 77.8% (14/18) of the control group, 66.7% (10/15) of the low SB group and 90.0% (9/10) of the moderate-high SB group. Conclusion The results showed that the first night effect on the occurrence of RMMA differed among the different degrees of the RMMA frequency, and suggest that, due to the first night effect, single-night polysomnography may underestimate the moderate-high level of SB but differentiate the low level of SB from controls.

Objectives : The aim of this study was to evaluate the relationship between masticatory muscle thickness and mandibular morphology in young Korean adults with normal occlusion and mandibular prognathism. Patients and methods Multidetector computed tomography (MDCT) was used to measure the masticatory muscle thickness on the right side in 100 Korean young adults (50 normal occlusion group, 50 mandibular prognathism group). Cephalometric analysis was done to measure mandibular morphology. Pearson correlation analysis was done to investigate the relationship between the masticatory muscle thickness and mandibular morphometry. Results The four masticatory muscles showed positive correlation with intergonial width in all subjects. All muscles, except temporalis, positively correlated with height of the ramus and mandibular length. Positive correlation was also observed in all muscles, except medial pterygoid, with thickness of the ramus. In the normal occlusion group, all four masticatory muscles showed positive correlation with intergonial width and ramus thickness. Positive correlation was also observed in all muscles (except lateral pterygoid) with mandibular length. Masseter and lateral pterygoid positively correlated with height of the ramus. In the mandibular prognathism group, all masticatory muscles, except lateral pterygoid, showed positive correlation with intergonial width. The masseter muscle showed negative correlation with ANB. Conclusion The results suggest a positive correlation of the thickness of masticatory muscles with both horizontal and vertical dimensions of the mandible. However, thickness of the masseter was found to decrease in patients with increasing severity of mandibular prognathism.

Trait anxiety is associated with an increased occurrence of awake bruxism episodes, a behavior characterized by clenching of the teeth contributing to temporomandibular disorders in some individuals. Here we measured the activity of the masseter and the intensity and duration of spontaneous wake-time tooth clenching episodes in healthy individuals with different levels of trait anxiety (TA). Two hundred fifty-five individuals completed a web survey. Using their TA scores, we allocated them in low ( 80th) TA groups. We analyzed the electromyographic (EMG) activity of the right masseter during a 15-min silent reading task in forty-three individuals with low (n = 12), intermediate (n = 17), and high TA (n = 14). We tested between-group differences in EMG activity of the masseter, as well as postural activity—the muscular activity that maintains mandibular posture, and amplitude and duration of spontaneous tooth clenching episodes. The activity of the masseter (mean ± SEM %maximum voluntary contraction/MVC) was greater in the high TA (10.23 ± 0.16%MVC) than the intermediate (8.49 ± 0.16%MVC) and low (7.97 ± 0.22%MVC) TA groups (all p 0.05). The EMG amplitude of tooth clenching episodes was greater in the high TA (19.97 ± 0.21 %MVC) than the intermediate (16.40 ± 0.24%MVC) and low (15.48 ± 0.38 %MVC) TA groups (all p < 0.05). The cumulative duration of clenching episodes was not different between groups (p = 0.390). Increased TA is associated with both increased masseter muscle activity and intensity of wake-time tooth clenching episodes. TA may contribute significantly to masticatory muscle overload.

BACKGROUND Clinical findings suggest that orthodontic treatment with clear aligners (clear aligner therapy/CAT) may cause masticatory muscle soreness in some patients. OBJECTIVE This multi-site prospective study investigated tooth pain and masticatory muscle soreness and tenderness in patients undergoing CAT and explored whether psychological traits affected these outcomes. METHODS Twenty-seven adults (22F, 5M; mean age ± SD=35.3 ± 17.6 years) about to start CAT were recruited at three clinics. During CAT, they reported on 100-mm visual analogue scales their tooth pain, masticatory muscle soreness and stress three times per day over 4 weeks (week 1 = baseline; week 2 = dummy aligner; week 3 = first active aligner; week 4 = second active aligner). Pressure pain thresholds (PPTs) were measured at the masseter and temporalis at baseline and after week 4. Mixed models were used to evaluate the outcome measures over time. RESULTS Clear aligner therapy caused mild tooth pain, which was greater with the passive than the first and second active aligners (both P

The article presents the results of a study of a specially developed map proposed by the authors in 84 patients with TMJ DM aged from 20 to 60 years, and 36 patients without TMJ dysfunction were selected as a control. According to the results of the study, the authors found that the main number of patients accounted for 59.6% after 40 years and among women - 61.9% of cases; also found in patients 46.42% occlusive-articulatory syndrome, 33.33% neuromuscular syndrome and 20.23% dislocation of the intra-articular disc; that the relationship between the amplitude of the vertical movement of the lower jaw, changes in the bioelectric potential of the masticatory muscle and the occurrence of these pathologies

The current state of portable/wearable electromyographic (EMG) devices for assessment of bruxism was reviewed.A search of full-text articles relevant to portable/wearable EMG devices capable of being used at home was performed. The data source used was MEDLINE via PubMed from January 1970 to July 2019.There were nine kinds of wearable EMG devices capable of being used under unrestrained conditions. Ultra-miniaturized wearable EMG devices with a level of performance equivalent to that of conventional stationary EMG devices have been developed and are being used during sleep and in the daytime. The devices have a high level of diagnostic accuracy for sleep bruxism. A definite cut-off value for awake bruxism has not been established.Assessment of sleep bruxism with a high level of accuracy can be performed using a portable/wearable EMG device. However, a definite cut-off value is required for assessment of awake bruxism.

Purpose: The aim of the research was to evaluate the masticatory muscle performance with different resilient denture base materials in maxillary single denture. Material and methods: Six patients were included in this cross over study. In the first stage of the study, the patients were instructed to use the denture (PMMA denture base) for 1 month and the masticatory muscle activity was assessed in the second and fourth weeks after delivery. A wash out period of two weeks was applied in this study to eliminate the effect of the previous denture then the denture material was relined to soft liner, then replaced with breflex flexible material. For each type of denture base relining material, EMG was recorded after 2 weeks form day of denture insertion (adjustment phase) then EMG was recorded after 4 weeks after complete muscles adaptation (adaptation phase). Results: Comparison between three types of denture bases was performed by one way ANOVA test which revealed significant difference between them regarding duration and amplitude of both masseter and temporalis after 2 weeks and after 4 weeks as P

Treatment of common myogenic oriented orofacial pain in dentistry using occlusal orthotics has been shown to be effective in reducing masticatory muscle discomfort and dysfunction.

Objective: To examine whether asymmetry in the area of occlusal contact and near contact (ACNC) and asymmetrical masticatory muscle electromyographic activity are correlated in healthy dentate adul...

Study objectives The coexistence of sleep-related breathing disorders (SRBD) and sleep bruxism (SB) is often mentioned in the literature. Polysomnography (PSG) with video recording gives the best opportunity to identify both of these phenomena. This study aimed to evaluate the relationship between SRBD and SB. Methods Patients from the Clinic of Prosthetic Dentistry operating at Wroclaw Medical University with diagnosed probable SB were subjected to one-night video-polysomnography. PSGs were evaluated according to standard sleep criteria. The results of the examination were analyzed for the occurrence of SB and SRBD. The Bruxism Episodes Index (BEI) and the types of electromyographical pathways (phasic, tonic, mixed) were used to evaluate SB. The Apnea/Hypopnea Index (AHI) and Oxygen Desaturation Index (ODI) were used to assess respiratory events. Subjects were divided into two groups according to SB occurrence: the studied group (bruxers, BEI ≥ 2) and control group (non-bruxers, BEI Results Quantitative analysis showed a lack of a statistically significant relationship between BEI and AHI (p = 0.82) and ODI (p = 0.90) in the studied group and controls. Qualitative analysis showed that the increase in both AHI and ODI was statistically significantly correlated with the increase in the number of tonic types of electromyographical pathways (p = 0.047, p = 0.006, respectively). Conclusions This study showed a significant relationship between tonic electromyographic pathways in SB episodes and SRBD. Tonic muscle contractions can be cause and effect for the formation of respiratory events. The occurrence of tonic episodes may be the key to understanding the causal relationship between SB and SRBD and should be more precisely examined. Clinical trial Evaluation of Selected Disorders with Sleep Bruxism, www.ClinicalTrials.gov , identifier NCT03083405.

Currently, the functional diagnosis of the entire dentition state is becoming an integral part of orthodontic and temporomandibular joint (TMJ) disorders correction. Aim — to study the functional state of the masticatory muscles in patients with muscular-articular dysfunction before and after using an soft occlusal splint. Materials and methods. A comprehensive examination of 478 patients (63% women, 37% men), aged 18 to 50 years, with various types of the dentition occlusion and muscular-articular TMJ dysfunction was performed. The main methods of functional diagnostics included: 1) masticatory muscle electromyography on Synapsis electromyograph (NeuroTech, Russia); 2) occlusion computer analysis with T-Scan III (Teksan, USA). Results. This work has established, based on the masticatory muscles functional state study, that bioelectrical activity was higher in the temporal muscles than in the masticatory muscles with the coefficient of symmetry from 2 to 4.5 in 65% of patients. After using an soft occlusal splintfor 6—12 months, the data of functional research methods confirm an improvement in the state of masticatory muscles in 84% of patients with TMJ. Conclusions. The obtained results have confirmed the fact of the masticatory muscles functional state improving with effectiveness of an soft occlusal splint use in patients with muscular articular TMJ dysfunction.

Objective: Bruxism is a condition defined as a masticatory muscle activity with an unexplored genetic background. The aim of this study was to evaluate the association between genetic polymorphisms in ACTN3 and bruxism. Study design: A total of 151 biological-unrelated children, aged 7–12 years were included in a case control ratio of 1:1.5. The data collection was performed during interview and clinical examination. Saliva samples were collected from all children and 3 genetic polymorphisms in the ACTN3 (rs678397, rs1671064 and rs1815739) were selected for genotyping using real time PCR. Pearson chisquare calculation was used to assess Hardy-Weinberg equilibrium and to evaluate the association between genotypes and alleles frequencies for each genetic polymorphism in the co-dominant and recessive models. An alpha of 5% was used. Results: The genetic polymorphisms rs678397, rs1671064 and rs1815739 were associated with bruxism in the co-dominate model and in the recessive model (p

Objectives To characterize eye movements during rhythmic masticatory muscle activities (RMMAs) in patients with sleep bruxism (SB). Methods Polysomnographic (PSG) recordings were performed on SB patients and normal controls during sleep (n = 8 for each group) and wakefulness (n = 9 for each group). The eye movements associated with episodes of RMMAs/SB during sleep and jaw movements during wakefulness were analyzed. Results During sleep, all episodes of RMMAs/SB in the SB patients and controls were associated with eye movements and most of the RMMAs/SB related slow eye movements (SB patients: 96.29%, 1583/1644; Controls: 97.49%, 543/557) were horizontal in the SB patients and controls. During wakefulness, all of the series of jaw movements were associated with eye movements. Most of cycles of jaw movements (SB patients: 88.89%, 200/225; Controls: 95.11%, 214/225) were associated with slow eye movements and most of the eye movements (SB patients: 52.50%, 105/200; Controls: 61.21%, 131/214) were vertical. There were significant correlations between the durations of episodes of eye movements and RMMAs/SB during sleep and between the duration of episodes of eye movements and duration of series of jaw movements during wakefulness in the SB patients and controls. Conclusions Most of RMMAs/SB episodes during sleep and jaw movements during wakefulness are associated with eye movements in SB patients and normal controls.

Background The influence of the stomatognatic system on human posture control has been investigated under static conditions, but the effects on dynamic balance have not yet been considered. Objective Investigating the influence of different functional stomatognatic activities (jaw clenching (JAW), tongue pressing (TON) and habitual jaw position (HAB)) on postural performance during a dynamic reactive balance task. Methods Forty-eight physically active and healthy adults were assigned to three groups differing in oral-motor tasks (JAW, TON or HAB). Dynamic reactive balance was assessed by an oscillating platform which was externally perturbed in four directions. Performance was quantified by means of Lehr's damping ratio. Mean speeds of the selected anatomical regions (head, trunk, pelvis, knee and foot) were analysed to determine significant performance differences. Results The groups differed significantly in balance performance in direction F (i.e., forwards acceleration of the platform). Post hoc tests revealed that the JAW group had significantly better performance compared with both the HAB and TON groups. Better performance was associated with a decreased mean speed of the analysed anatomical regions. Conclusion JAW can improve dynamic reactive balance but the occurrence of positive effects seems to be task-specific and not general. TON seems not to have any observable effects on dynamic reactive balance performance, at least when evaluating it with an oscillating platform. JAW might be a valuable strategy which could possibly reduce the risk of falls in elderly people; however, further investigations are still needed.

Background Preserving sufficient oral function and maintaining proper nutrition are essential to prevent frailty. Thus, we have developed "munchy" foods that contain harder textures and are rich in protein. Objectives This study aimed to test the effects of masticating textured foods on masticatory muscle activity in young and older adults. Methods Twenty young and 32 community-dwelling older individuals participated in this study. After measuring oral function, we subdivided the older participants into normal and oral hypofunction (OHF) groups. Two test foods (meatloaf and chicken ball) were prepared to have a harder texture using specific ingredients (munchy) or not (control). The participants ate 10 g of the test foods in random order while being measured for masseter muscle activity with a surface electromyogram (EMG). We calculated the number of chewing cycles and integrated muscle activity of the masseter muscle from the EMG data and tested for differences by food texture or age group. Results The number of chewing cycles, mean EMG amplitude and integrated EMG activity was significantly higher for the munchy foods than for the controls for all groups. The integrated masseter muscle EMG activity was significantly increased in the normal older group than in the young group for both food types, but not significantly different between in OHF and young groups. Conclusions Our findings suggest that eating textured foods will lead to increased masticatory load and therefore increased muscle activity, especially in older adults. Application of textured food may change dietary habits in older adults.

Introduction. Temporomandibular disorders (TMDs) are a heterogeneous group of pathologies affecting the temporomandibular joint (TMJ), the jaw muscles, or both. Epidemiological studies of TMD reveal a prevalence of 82% in the general population with 48% of them presenting with clinical features of muscle tenderness and difficulty in mouth opening. TMD are considered to be the most common orofacial pain conditions of nondental origin. Methods. The patients with TMD were randomly divided into two groups, A and B, based on their VAS scale. Group A consists of two subgroups 1 and 2 each consisting of 15 patients. Group B consists of two subgroups 3 and 4 consisting of 15 patients. Patients in Group A were given TENS for twenty minutes, and the frequency is adjusted as follows: (i) subgroup 1: TENS frequency at a range of 0–5 (VAS measuring 1–5) and (ii) subgroup 2: TENS frequency at a range of 5 and above (VAS measuring 6–10). Patients in Group B were given MENS for twenty minutes, and the frequency adjusted as follows: (i) subgroup 3: MENS frequency at range of 0–5 (VAS measuring 1–5) and (ii) subgroup 4: MENS frequency at a range of 5 and above (VAS measuring 6–10). Each patient was recalled for five consecutive days for the treatment, and the same intensity and frequency were maintained throughout the treatment period. Results. The improvement in VAS is seen to be highly significant statistically in MENS subgroup 4 (moderate-to-severe pain). Subgroups 1 and 3 had improvement in VAS which was comparable in both TENS and MENS groups. Conclusion. In the present study, it was found that TENS and MENS are equally effective in improving the functional mouth opening. MENS showed better and immediate effect in relief of pain. Microcurrent also has the advantage of being subthreshold, and hence the side effects such as tingling sensation and paresthesia seen to occur in some patients following TENS are absent. TENS and MENS can be considered as the first line of treatment in patients with acute and chronic masticatory muscle pain and also as an effective treatment option in cases of functional mouth opening.

Background. Tenderness of masseters and temporalis can be considered a relevant tool for diagnosis of myo-type craniofacial pain disorders, but a limit of pain score systems is that they are based on subjective pain perception. Surface electromyography (sEMG) is a noninvasive and reliable tool for recording muscle activity. Therefore, we investigated whether a correlation exists between tenderness on masseters and temporalis, assessed by subjective pain scale, and muscles activity, evaluated by sEMG, in patients with painful temporomandibular disorder (TMD) and concurrent tension-type headache (TTH). Methods. A cross-sectional study on fifty adult volunteer patients with TMD and TTH, who underwent tenderness protocol according to Diagnostic Criteria for TMD (DC/TMD) guidelines, was conducted followed by sEMG recording of temporalis and masseters. Pearson’s correlation was performed to investigate the correlation between muscular activity and subjective pain scores. Results. An overall moderate correlation between muscle tenderness and sEMG values (y = 1 + 1.2 · x; r2 = 0.62; p<0.0001), particularly in the temporalis, was observed. Segregation of data occurred according to tenderness and sEMG values. At the highest pain score, the mean sEMG absolute value was higher at the temporalis than the masseters. Conclusions. Our study provides evidence that subjective pain perception can be objectively quantified at a magnitude proportional to pain severity. At greater tenderness scores, higher sEMG activity at the level of temporalis could help discriminate clinically prevalent TTH versus prevalent TMD. sEMG confirms to be an accurate tool to reliably objectify the subjective perception of pain. When combined with clinical evaluation and patients’ symptoms, sEMG increases diagnostic sensitivity in the field of myo-type craniofacial pain disorders. This trial is registered with NCT02789085.

The relation between occlusal force and general motor ability induced by lower-limb musculature is unclear. To identify indicators of oral and lower-limb muscle weakness, this study examined the relation between masticatory muscle strength and lower limb muscle force in 742 community-dwelling elderly adults (315 men and 427 women, mean age 733 +/- 5.5 years) living in Itabashi ward, Tokyo. Multiple regression analysis of the relation between occlusal force and knee extension torque, in relation to age and sex, showed a significant correlation between the two variables (r = 0.348, P < 0.001), which indicates that occlusal force is a determinant of knee extension torque. Occlusal force remained significantly correlated with knee extension torque after adjustment for factors known to be related to the latter. In conclusion, chewing function and lower-limb motor function were significantly correlated and thus might be indicators of muscle weakness in elderly adults.

Objectives: This study aimed to assess frequency and multiple-night variability of sleep bruxism (SB) as well as sleep-time masticatory muscle activities (sMMA) in the home environment in healthy young adults using a portable device that provides electrocardiographic (ECG) and surface electromyographic (EMG) recordings from the masticatory muscles. Methods: The study was performed on 27 subjects (11 males, 16 females, mean age 28.3 &plusmn, 1.7 years) selected from a sample of healthy young students. Evaluation was carried out for four nights to record data on masticatory muscle activities using a compact portable device that previously showed an excellent agreement with polysomnography (PSG) for the detection of SB events. The number of SB episodes per sleep hour (bruxism index), and the number of tonic, phasic and mixed sMMA events per hour were assessed. A descriptive evaluation of the frequency of each condition was performed on all individuals, and gender comparison was investigated. Results: Mean sleep duration over the four recording nights was 7 &plusmn, 1.3 h. The average SB index was 3.6 &plusmn, 1.2. Most of the sMMA were tonic (49.9%) and phasic (44.1%). An ANOVA test showed the absence of significant differences between the four nights. No significant gender differences were detected for the SB index, phasic or tonic contractions, conversely, gender differences were detected for mixed sMMA events (p &lt, 0.05). Conclusion: This investigation supports the concept that sMMA events are quite frequent in healthy adults. Differences over the four-night recording span were not significant. These data could be compared to subjects with underlying conditions that may lead to an additive bruxism activity and possible clinical consequences.

Mandibular angle osteotomy with outer cortex grinding has become the preferred cosmetic procedure for correcting square faces. After surgery, bone hyperplasia at the mandibular angle affects the operation result. This study evaluated the effect of the masticatory muscles on bone repair. From January 2016 to January 2019, patients who underwent mandibular angle osteotomy with outer cortex grinding were retrospectively reviewed. Computed tomography data of these patients were collected, and the bone volume of the mandibular angle changes and its correlation with masticatory muscle morphology were analyzed. Computed tomography data measurement results showed that a large amount of bone in the mandibular angle area was removed by the operation; however, the long-term follow-up results showed that there was bone hyperplasia in the mandibular angle areas. Compared with the immediate postoperative bone volume, the difference was statistically significant (P

Aim: Bruxism is defined as the involuntary recurrent masticatory muscle activity characterized by gnashing, grinding, clenching of teeth, and/or pushing the mandible. Factors creating its etiology are peripheral (morphological) or central (physiopathological and physiological), and exogenous. Recently, among physiological factors, depression and bruxism were considered to be related. A definitive treatment method does not exist for bruxism; however, botulinum toxin-A (BT-A) application is an up-to-date and effective way of treatment. The present study is aimed to evaluate the levels of depression in bruxism patients treated with BT-A application. Materials and Methods: A total of 25 individuals (23 females and 2 males) who were diagnosed as bruxism patients were included in the study. 25 U of BT-A for each masseter muscle was injected into the patients. Patients were prospectively observed for a possible change in depression levels by using Beck’s Depression Inventory. The inventory was implemented before and six months after the BT-A application. Depression levels before and six months after the injection were compared. A paired t-test was used to compare “before” and “after” treatment values. One-way analysis of variance and post-hoc Tukey tests were used to evaluate the change in Beck’s Depression Inventory scores according to age groups. Results: The mean total score was 7.80 ± 8.10 before the treatment and 7.16 ± 6.52 six months after the treatment. The decrease in the mean score was not statistically significant ( P > .05). Conclusion: In conclusion, despite the decrease in the mean Beck’s Depression Inventory scores, a statistically significant decrease in the depression levels of patients was not observed.

BACKGROUND Muscle-related temporomandibular disorders (TMD) may affect the masticatory function. Chewing function can be assessed objectively using bolus-kneading tests, such as two-colour chewing-gum mixing ability test. OBJECTIVE The aim was to compare the masticatory function with a two-colour chewing-gum test before and after treatment of the masticatory muscle-related temporomandibular disorder. METHODS Twenty-one patients with masticatory muscle disorder according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were recruited as an experimental group, and further twenty-one participants without any TMD were included as controls. Pain intensity (scored on a visual-analogue scale) and maximum mouth opening (MMO) were recorded. Jaw Functional Limitation Scale-8 (JFLS-8) was conducted on all patients. Before and after treatment, masticatory function was evaluated with a validated bolus-kneading test, using two-colour chewing gum. RESULTS There was no statistically significant difference in chewing function before and after treatment in the experimental group (p��=��.715). When these values were compared with the control group, there were no statistically significant differences (p��=��.489, p��=��.890). There was no correlation between masticatory function and VAS, MMO, JFLS-8 before and after treatment in the experimental group. CONCLUSION The two-colour chewing-gum test is not sensitive when the masticatory performance is not severely impaired.

BACKGROUND: Ambulatory electromyographic (EMG) devices are increasingly being used in sleep bruxism studies. EMG signal acquisition, analysis and scoring methods vary between studies. This may impact comparability of studies and the assessment of sleep bruxism in patients. OBJECTIVES: (a) To provide an overview of EMG signal acquisition and analysis methods of recordings from limited-channel ambulatory EMG devices for the assessment of sleep bruxism; and (b) to provide an overview of outcome measures used in sleep bruxism literature utilising such devices. METHOD: A scoping review of the literature was performed. Online databases PubMed and Semantics Scholar were searched for studies published in English until 7 October 2020. Data on five categories were extracted: recording hardware, recording logistics, signal acquisition, signal analysis and sleep bruxism outcomes. RESULTS: Seventy-eight studies were included, published between 1977 and 2020. Recording hardware was generally well described. Reports of participant instructions in device handling and of dealing with failed recordings were often lacking. Basic elements of signal acquisition, for example amplifications factors, impedance and bandpass settings, and signal analysis, for example rectification, signal processing and additional filtering, were underreported. Extensive variability was found for thresholds used to characterise sleep bruxism events. Sleep bruxism outcomes varied, but typically represented frequency, duration and/or intensity of masticatory muscle activity (MMA). CONCLUSION: Adequate and standardised reporting of recording procedures is highly recommended. In future studies utilising ambulatory EMG devices, the focus may need to shift from the concept of scoring sleep bruxism events to that of scoring the whole spectrum of MMA. ispartof: JOURNAL OF ORAL REHABILITATION vol:48 issue:7 pages:846-871 ispartof: location:England status: published

Study Objectives The present study aimed to clarify the physiological relationships between rhythmic masticatory muscle activity (RMMA) and cyclic changes in cortical, autonomic, and arousal-motor activities during sleep in sleep bruxism (SB) children. Methods Polysomnographic recordings were performed on 15 SB children (9 boys, 6 girls, 10.3 ± 2.5 years) and 18 control children (5 boys, 13 girls, 10.7 ± 3.1 years) free from sleep and developmental disorders. Sleep and RMMA were scored by the standard rules. Sleep cycle was divided into NREM and REM sleep segments and the frequency of RMMA, transient arousal and movement, and cortical and cardiac activities were then quantitatively analyzed in relation to sleep cycles. Results Neither sleep architecture nor sleep stage distribution of RMMA significantly differed between the two groups. In sleep cycles, SB children showed more frequent RMMA in all segments than controls, while cyclic changes in cortical and autonomic activities did not significantly differ between the two groups. In SB children, RMMA was the most frequent in the last NREM segment before REM sleep and was associated with increases in cortical beta activity and arousal; more than 70% of RMMA time-dependently occurred with cortical and motor arousals. Conclusions This is the first study to suggest that the potentiation of RMMA occurrence was associated with transient arousal under cyclic sleep processes in primary SB children.

BACKGROUND Little is known about wake-time masseter activity of patients with masticatory muscle pain in real-life settings. OBJECTIVES The aims of this study were (1) to assess wake-time masseter activity of women with masticatory muscle pain (MMP) and compare it with that of pain-free women; and (2) to investigate the association between objectively measured masseter contractions and self-reported oral behaviours. METHODS Adult women (N = 27) diagnosed with MMP were age-matched with pain-free women (N = 26). The electromyographic (EMG) activity of the masseter muscle when awake was recorded unilaterally for two consecutive days. The number of contraction episodes and relative contraction time (%) were calculated using cut-off thresholds of 3%, 5% and 10% of maximum voluntary contraction (MVC). Self-reported daytime oral activity was assessed using the Oral Behaviours Checklist (OBC, items 3-21). Data were analysed using univariate tests and mixed-model analyses. RESULTS The number of contraction episodes was similar between groups for all detection thresholds, but the relative contraction time at the lower detection thresholds (i.e. 3% MVC and 5% MVC) was significantly longer (1.5-fold) in the MMP than in the pain-free group. The OBC scores were significantly higher in the women with MMP than in controls, but no positive association could be found between EMG variables and OBC scores. CONCLUSION Women with MMP engage in low-level masseter muscle contractions, which last longer than those of pain-free controls. There was no relationship between self-reported oral behaviours and masseter activity when awake. These findings support the notion that prolonged low-level clenching when awake may play a role in the pathophysiology of MMP.

The purpose of this study was to determine the characteristics of masticatory muscle activity and various oral condition factors, and to analyze their associations in order to improve the prevention and diagnosis of masticatory muscle-related diseases. This study included 30 Korean females (mean age of 20 years, age range of 19-21 years). Participants were instructed to complete a self-written questionnaire on factors that may affect their muscle activity. Surface electromyography was used to measure the activity of the masseter and temporalis muscles. We also observed the buccal mucosa ridge, tongue indentation, tooth cracks and fractures, and mandibular tori in the oral cavity. Spearman correlation analysis and the nonparametric Mann-Whitney U test were applied to the data. When subjects had temporomandibular disorder, the right temporalis muscle exhibited significantly lower activity (P

This case report describes a rare side effect associated with nasal continuous positive airway pressure (nCPAP), masticatory muscle myalgia. A 69-year-old man was referred to a clinic specializing in orofacial pain and dysfunction with complaints of pain in the area of the masseter muscles. He was diagnosed with severe obstructive sleep apnea (OSA) 9 months earlier, for which he received nCPAP. Six months ago, his pain complaints started. The pain was diagnosed as masticatory muscle myalgia, due to sleep-related tooth clenching and intense tongue thrusting. These activities were likely related to the patient’s attempts to prevent leakage through the oral cavity of the airflow generated by the nCPAP device. The patient did not complain about leaking of the nasal mask itself. Considerable alleviation of the pain complaints as well as reduction of the clenching and thrusting behavior were achieved by substituting the nasal mask with a full face mask. Sleep medicine physicians should be aware of this possible side effect of nCPAP. CITATION: Lobbezoo F, Li J, Koutris M, et al. Nasal CPAP therapy associated with masticatory muscle myalgia. J Clin Sleep Med. 2020;16(3):455–457.

Aim: Temporomandibular disorders (TMD) refer to functional disorders of the masticatory system, temporomandibular joint (TMJ) and masticatory muscles. The main objective of this study was to determine whether and to what extent temporomandibular disorders (TMD) affect the maximum bite force (MBF). Methods: The present study included subjects with and without temporomandibular disorder. The presence of TMD was assessed by means of the Helkimo clinical dysfunction index analysis. We measured the maximum bite pressure (MBP) and occlusal contact area (OCA) by means of a Fuji Prescale Pressure measurement film. Based on the MBP and OCA values obtained, MBF values were determined. Results: The MBF values were significantly lower in patients with TMD compared to subjects without TMD (P Conclusion: TMDs have a significant impact on MBF and masticatory muscle action potential. More research is needed to determine the impact of reduced maximum bite force on the functional efficiency of the masticatory system.

Objective: To assess the masticatory muscle activities in patients with temporomandibular disorders (TMD) with centric relation (CR)-maximum intercuspation (MI) discrepancy and absence of anterior/lateral guidance by electromyography (EMG). Methods: Forty-six patients with TMD and 34 controls underwent clinical evaluations and EMG recordings at baseline. Twenty-three patients and 17 controls wore a stabilization splint. The remaining subjects were followed up without any intervention. After 3 months, the EMG recordings and clinical evaluations were repeated. Results: At baseline, the EMG values at rest and EMG value variations after movements in patients were higher than those in controls. After treatment, no difference was observed between EMG values of patients and controls. Conclusion: In the present study, patients with TMD had abnormal muscular activities. The stabilization splint is effective for functional recovery of the masticatory muscles, possibly by eliminating the CR-MI discrepancy and establishing anterior/lateral guidance.

Purpose: To determine the accuracy of scoring masticatory muscle activity (MMA) events in seven different polysomnography (PSG) setups. Methods: Nineteen volunteers (13 females, 6 males, age 31.1 ± 12.9 years, 12 self-proclaimed bruxers) attended one-night PSG recording, supplemented with audio, video, and a separate frontal electroencephalography electrode set (FES). The same examiner scored the MMA events with seven different setups, with varying number of channels available: (1) one, (2) two, and (3) four EMG channels, (4) PSG without audio or video (PSG-N), (5) home PSG with FES and audio (FES-A), (6) PSG with audio (PSG-A), and (7) PSG with audio and video (PSG-AV). A subset (n = 10) of recordings was scored twice to determine intra-scorer reliability. MMA indices and accuracy of scoring the events in different setups were compared against PSG-AV. Results: The intra-class correlation coefficient (ICC) between PSG-AV and PSG-A was high (0.940, p 0.939 for all setups), with the exception of PSG-N (ICC = 0.764, p = 0.002). When comparing against the MMA events scored in PSG-AV, the sensitivity of MMA event recognition for PSG-A was 78.5% and specificity 95.5%, which were substantially higher than sensitivity (52.0%) and specificity (87.2%) of PSG-N. Conclusions: MMA event scoring accuracy with PSG-A or FES-A is almost comparable to PSG-AV. Since precise event recognition is essential for accurate MMA scoring, it is evident that one cannot rely exclusively on EMG.

Patients with masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) experience limited mouth opening due to restricted muscle extension. Hyperplastic aponeurosis and tendons lead to the restriction of muscle extension. The criteria for the diagnosis of MMTAH are limited mouth opening that progresses very slowly from adolescence, intraoral palpation reveals a hard cord-like structure along the overhang of the anterior border of the masseter muscle on maximum mouth opening, and a square mandible. Conservative treatment, including pharmacotherapy, occlusal splint and physical therapy are ineffective. The standard therapy is surgical treatment, such as anterior partial aponeurectomy of the masseter muscle and coronoidectomy. The long-term results are very satisfying.

Purpose We morphometrically analyzed human facial muscles, and evaluated the Yanagihara facial nerve grading system using our data. Methods We used 15 types of human facial muscle, 2 types of masticatory muscle and 2 types of skeletal muscle. The materials were obtained from 11 Japanese male cadavers aged 43–86 years. We counted the muscle fibers and measured the transverse area of the muscle fibers (TAMF), and then calculated the number of muscle fibers (NMF) per mm2 and the average TAMF. Results We found a significant correlation between average TAMF and NMF (r = − 0.70; p

OBJECTIVES To test if there was a correlation between night-time masticatory muscle activity, as measured by duty factors, and ultradian cycling of autonomic nervous system (ANS) spectral powers in subjects without temporomandibular disorder (TMD)-related pain. SETTING AND SAMPLE POPULATION The University of Missouri-Kansas City School of Dentistry. Three women and four men of average ages 38 ±8 and 56 ± 17 years, respectively, gave informed consent to participate. MATERIAL AND METHODS Investigators taught subjects to record heart (electrocardiography, ECG) and masticatory muscle activities (electromyography, EMG). ECG recordings were analysed for ANS ultradian cycling by a polynomial fit to the ratio of sympathetic and parasympathetic spectral powers (ms$^{2}$ ). Masseter and temporalis EMG recordings were analysed over 20-minute epochs around peaks and valleys in the ANS ultradian cycles. Duty factors (% time of masticatory muscle activity/20-minute epoch) were determined relative to average threshold EMG (T$_{EMG}$ ) required to produce a given bite force (N). Regression analyses quantified relationships between normalized muscle duty factors and ANS spectral powers. RESULTS Subjects made a total of 27 sets of night-time ECG and EMG recordings that averaged 6.6 ± 1.1 hours per recording. Highest average duty factors were associated with T$_{EMG}$ of 1-2 N and showed cumulative masseter and temporalis activities of 9.2 and 8.8 seconds/20-minute epoch, respectively. Normalized masticatory muscle duty factors showed non-linear relationships with normalized sympathetic (R$^{2}$ = +0.82), parasympathetic (R$^{2}$ = -0.70) and sympathetic/parasympathetic spectral powers (R$^{2}$ = +0.75). CONCLUSIONS Night-time ANS spectral powers showed ultradian cycling and were correlated with masseter and temporalis muscle activities in adult subjects without TMD.

BACKGROUND: Most rhythmic masticatory muscle activities (RMMAs) have been shown to be accompanied with limb movements (LMs) in sleep bruxism (SB) patients during sleep.OBJECTIVES: To compare the relationships between RMMAs and LMs in SB patients and normal subjects.METHODS: Polysomnographic recordings were performed on eight SB patients and nine normal subjects and the frequencies and durations of RMMAs as well as LMs were determined. Linear regression and correlation analysis was performed to study the relationship between durations of RMMAs and LMs when RMMAs occurred with LMs.RESULTS: Most LMs in SB patients, but not in normal subjects, were accompanied with RMMAs. RMMAs in SB patients were more likely to be isolated, phasic or mixed, while RMMAs in normal subjects were more likely to be tonic. The frequencies of LMs, isolated RMMAs and RMMAs accompanied with LMs in SB patients were significantly higher than those in normal subjects. Furthermore, linear regression and correlation analysis showed that duration of RMMAs was significantly associated with that of LMs when RMMAs occurred with LMs. The duration of RMMAs, when accompanied with LMs, in SB patients was significantly longer than that in normal subjects.CONCLUSIONS: Close relationships between LMs and RMMAs exist in SB patients and normal subjects, and SB episodes may be part of cortical arousal responses and the increased cortical activities associated with SB episodes may not just be localized to the central nervous system (CNS) that controls jaw movements but may also include other parts of CNS that controls LMs. This article is protected by copyright. All rights reserved.