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Objectives This study aimed to assess whether awake bruxism and masticatory muscle activity could be related to external root resorption (ERR) in second molars adjacent to impacted mandibular third molars. Materials and methods Sixty patients, with requests for a cone-beam, computed tomography, were divided into two groups: ERR (patients with ERR in the second molar, n  = 30), and control group ( n  = 30). Awake bruxism was assessed through the Oral Behaviors Checklist (OBC) and an ecological momentary assessment (EMA). Surface electromyography (EMG) was used to assess the masseter and anterior temporal muscle function. Normality and homogeneity of variances were demonstrated. Descriptive analysis was performed, using the T-test and Chi-square test to compare the characteristics of the groups. A multiple regression model was performed. Results The ERR group presented more non-functional oral activities related to awake bruxism than the control group, according to OBC ( p  = 0.027) and EMA ( p  = 0.035). In addition, the ERR group had higher EMG activity than the control group in rest and isotonic protocols ( p  < 0.05). Conclusions Awake bruxism and greater masticatory muscle activity seem to be related to the presence of ERR in second molars adjacent to impacted mandibular third molars. Clinical relevance The results of the present study can reinforce the theory that triggering ERR in the second molars adjacent to impacted mandibular third molars may be related to mechanical forces coming from the masticatory function.

Background To evaluate the effect of Low Level Laser (LLL) application at the points of greatest pain in patients with chronic masticatory muscle pain. Methods A total number of 30 (21 women, 9 men, with a mean age of 39.2) were selected after the diagnosis of MPDS according to the Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD). The patients were randomly divided into three groups; laser group I ( n  = 10); patients received the LLL at the point of greatest pain, laser group II ( n  = 10); patients received LLL at pre-established points in the effected muscles and placebo group ( n  = 10). LLL and placebo were applied three times per week, for a total of 12 sessions. Mandibular mobility was examined, masticator muscles tenderness were assessed and PPT values were obtained. Subjective pain levels were evaluated using VAS. The measurements performed before the treatment and after the completion of the therapy. Descriptive statistics (mean, standard deviation, and frequency) Student’s t -test, Mann–Whitney U -test and paired-sample t -tests were used for analysis. Results In both laser groups, there was a statically significant reduction in PPT values of the muscles, number of muscles without any pain on palpation increased significantly, mandibular movements’ ranges were improved. Laser group I demonstrated statistically better results than the Laser group II in all of the measured values. Plasebo group did not show any statistically difference in any of the measured values. Conclusions LLLT can be accepted as an alternative treatment modality in the management of masticatory muscle pain and direct irradiation seems to effect better. Trial registration Current Controlled Trials ISRCTN31085 , Date of registration 28/08/20145.

This study investigated the effect of low-level laser therapy (LLLT) on the masticatory performance (MP), pressure pain threshold (PPT), and pain intensity in patients with myofascial pain. Twenty-one subjects, with myofascial pain according to Research Diagnostic Criteria/temporomandibular dysfunction, were divided into laser group ( n  = 12) and placebo group ( n  = 9) to receive laser therapy (active or placebo) two times per week for 4 weeks. The measured variables were: (1) MP by analysis of the geometric mean diameter (GMD) of the chewed particles using Optocal test material, (2) PPT by a pressure algometer, and (3) pain intensity by the visual analog scale (VAS). Measurements of MP and PPT were obtained at three time points: baseline, at the end of treatment with low-level laser and 30 days after (follow-up). VAS was measured at the same times as above and weekly throughout the laser therapy. The Friedman test was used at a significance level of 5 % for data analysis. The study was approved by the Ethics Committee of the Federal University of Sergipe (CAAE: 0025.0.107.000-10). A reduction in the GMD of crushed particles ( p  < 0.01) and an increase in PPT ( p  < 0.05) were seen only in the laser group when comparing the baseline and end-of-treatment values. Both groups showed a decrease in pain intensity at the end of treatment. LLLT promoted an improvement in MP and PPT of the masticatory muscles.

Background Myofascial pain syndrome (MPS) is a particular type of temporomandibular joint disorder. Research findings comparing various treatment approaches are scarce and controversial. Therefore, this study aimed to compare the effectiveness of ultrasound therapy, stabilization splint, TheraBite device, and masticatory muscle exercises in reducing pain intensity and improving mandibular mobility in patients with MPS. Methods It was a single‐blind, randomized, parallel‐group, active‐controlled trial that took place between April 2023 and October 2023 at the Department of Fixed Prosthodontics, Damascus University. Patients older than 18 years old with myofascial pain accompanied by limited jaw opening and pain lasting for at least 6 months were included. Eighty patients were randomly assigned into four groups using online randomization software: ultrasound therapy, stabilization splint, TheraBite device, and masticatory muscle exercises. Only outcome assessors were masked to treatment allocation. The exercise regimen was the exercise program for patients with TMD. The following primary outcome measures were considered at the baseline (t0), at the first (t1), second (t2), and fourth (t3) week of treatment, and at the second (t4) and fifth (t5) month of follow‐up: pain intensity using the visual analogue scale, maximum interincisal opening, right lateral movement, and left lateral movement measured in millimeters. Results The pain level changed from severe to mild at t3 in ultrasound therapy, stabilization splint, and TheraBite device groups. In the masticatory muscle exercises group, it changed to moderate, with a significant difference between ultrasound therapy (p = 0.012) and stabilization splint (p = 0.013) groups. In addition, the mandibular mobility continued to improve at the subsequent follow‐up periods (t4 and t5). Conclusions All therapies are equally effective after 5‐month follow‐up. However, ultrasound therapy and stabilization splints have the benefit of achieving rapid improvement. Trial Registration ISRCTN20833186.

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.

Myofacial pain dysfunction syndrome (MPDS) is the most common reason for pain and limited function of the masticatory system. The effects of low-level lasers (LLLs) for controlling the discomfort of patients are investigated frequently. However, the aim of this study was to evaluate the efficacy of a particular source producing 660 nm and 890 nm wavelengths that was recommended to reduce of the pain in the masticatory muscles. This was a double-blind and placebo-controlled trial. Sixteen MPDS patients were randomly divided into two groups. For the laser group, two diode laser probes (660 nm (nanometers), 6.2 J/cm 2 , 6 min, continuous wave, and 890 nm, 1 J/cm 2 (joules per square centimetre), 10 min, 1,500 Hz (Hertz)) were used on the painful muscles. For the control group, the treatment was similar, but the patients were not irradiated. Treatment was given twice a week for 3 weeks. The amount of patient pain was recorded at four time periods (before and immediately after treatment, 1 week after, and on the day of complete pain relief). A visual analog scale (VAS) was selected as the method of pain measurement. Repeated-measures analysis of variance (ANOVA), the t -test and the paired t -test were used to analyze the data. In each group the reduction of pain before and after the treatment was meaningful, but, between the two groups, low-level laser therapy (LLLT) was more effective ( P  = 0.031) According to this study, this type of LLLT was the effective treatment for pain reduction in MPDS patients.

Background Low-level laser therapy (LLLT) has been shown to modulate the inflammatory process without adverse effects , by reducing pain and swelling and promoting the repair of damaged tissues. Because pain, swelling and muscle spasm are complications found in virtually all patients following oral surgery for the removal of impacted teeth, this model has been widely used to evaluate the effects of LLLT on the inflammatory process involving bone and, connective tissue and the muscles involved in mastication. Methods/Design After meeting the eligibility criteria, 60 patients treated at a Specialty Dental Center for the removal of impacted lower third molars will be randomly divided into five groups according to the type of laser therapy used at the end of surgery (intraoral irradiation with 660 nm laser; extraoral irradiation with 660 nm laser; intraoral irradiation with 808 nm laser; extraoral irradiation with 808 nm laser and no irradiation). To ensure that patients are blinded to the type of treatment they are receiving, the hand piece of the laser apparatus will be applied both intraorally and extraorally to all participants, but the device will be turned on only at the appropriate time, as determined by the randomization process. At 2 and 7 days after surgery, the patients will be evaluated by three blinded evaluators who will measure of swelling, mouth opening (muscle spasm evaluation) and pain (using two different pain scales). The 14-item Oral Health Impact Profile (OHIP-14) will be used to assess QOL. All data will be analyzed with respect to the normality of distribution using the Shapiro-Wilk test. Statistically significant differences between the experimental groups will be determined using analysis of variance, followed by a suitable post hoc test, when necessary. The significance level will be set at α = 0.05. Discussion The lack of standardization in studies with regard to the samples, methods and LLLT parameters complicates the determination of the actual effect of laser therapy on this model. The present study aims to provide a randomized, controlled, double-blind trial to compare four different LLLT parameters in relation to the outcomes of pain, swelling and muscle spasm following surgery for the extraction of impacted third molars and evaluate the effects os surgery on patients' quality os life (QOL). Trial registration Brazilian Registry of Clinical Trials - Rebec ( RBR-6XSB5H ).

Background The purpose of the present controlled clinical trial was to assess the effect of a single 60 min application of transcutaneous electrical nervous stimulation (TENS) at sensory stimulation threshold (STS), compared to the application of motor stimulation threshold (MTS) as well as to untreatment, on the surface electromyographic (sEMG) and kinesiographic activity of patients with tempormanbibular disorder (TMD). Methods Sixty female subjects, selected according to the inclusion/exclusion criteria, suffering from unilateral TMD in remission were assigned to MTS, STS or untreatment. Pre- and post-treatment differences in the sEMG activity of temporalis anterior (TA), masseter (MM), digastric (DA) and sternocleidomastoid muscles (SCM), as well in the interocclusal distance (ID), within group were tested using the Wilcoxon test, while differences among groups were assessed by Kruskal-Wallis test; the level of significance was set at p ≤ 0.05. Results Significant pre- and post-treatment differences were observed in MTS and STS groups, for TA and MM of both sides; no significant difference was detected between MTS and STS groups. Kinesiographic results showed that the vertical component of ID was significantly increased after TENS in MTS and STS groups. Conclusions STS TENS could be effective, as well as MTS, in reduce the sEMG activity of masticatory muscles and to improve the ID of TMD patients in remission. Future studies are needed to confirm the results of the present study. Clinical relevance. The present study demonstrates that the application of TENS is effective in reduce the sEMG activity, as well as in increasing the ID of patients with TMD; our study did not support superior effectiveness of MTS or STS. Trial registration ClinicalTrials.gov: NCT01832207

Background The stomatognathic system and dysfunction in this system may be related to postural control. The proposal of the present study is to assess the effect of mandibular mobilization in individuals with temporomandibular disorder using surface electromyography of the muscles of mastication and stabilometric variables. Methods/Design A randomized, controlled, blind, clinical trial will be carried out, with the participants divided into three groups: 1) facial massage therapy (control group), 2) nonspecific mandibular mobilization and 3) specific mandibular mobilization. All groups will be assessed before and after treatment using the Research Diagnostic Criteria for Temporomandibular Disorders, surface electromyography of the masseter and temporal muscles and stabilometry. This study is registered with the Brazilian Registry of Clinical Trials (RBR9x8ssz). Discussion A large number of studies have employed surface electromyography to investigate the function/dysfunction of the muscles of mastication and associations with signs and symptoms of temporomandibular disorders. However, it has not yet been determined whether stabilometric variables offer adequate reliability in patients with this disorder. The results of the proposed study will help determine whether specific and/or nonspecific mandibular mobilization exerts an effect on the muscles of mastication and postural control. Moreover, if an effect is detected, the methodology defined in the proposed study will allow identifying whether the effect is local (found only in the muscles of mastication), global (found only in postural control) or generalized.

This study tested the hypotheses that (1) parafunctional clenching increases pain and can lead to a diagnosis of temporomandibular disorder (TMD) pain and (2) electromyographic (EMG) activity during parafunctional clenching is significantly and positively correlated with reports of pain. Fourteen individuals without TMD participated in 5 consecutive days of 20-min long EMG biofeedback training sessions of the left and right temporalis and masseter muscles. Subjects were randomly assigned to either a Decrease or Increase group and were instructed to maintain EMG activity below 2 microV or above 10 microV during training, respectively. Two Increase subjects and no Decrease subjects were diagnosed, by a blinded examiner, with TMD pain following training. Self-reported pain posttraining was significantly higher for the Increase group. Masseter EMG activity was strongly correlated with pain. Parafunctional clenching increases pain and can lead to a diagnosis of TMD in otherwise pain-free individuals. Pain reports are positively correlated with the activity of the masseter muscle.