Anterior Temporalis Research Articles

Botulinum toxin type A and acupuncture for masticatory myofascial pain: a randomized clinical trial.

BoNT-A has been widely used for TMD therapy. However, the potential benefits compared to dry needling techniques are not clear. Objective this study aimed to compare the immediate effects of botulinum toxin type A (BoNT-A) injections and Acupuncture in myofascial temporomandibular disorders (TMD) patients.Methodology 54 women were divided into three groups (n=18). AC patients received four sessions of traditional acupuncture, being one session/week during 20-min. BoNT-A patients were bilaterally injected with 30U and 10U in masseter and anterior temporal muscles, respectively. Moreover, a control group received saline solution (SS) in the same muscles. Self-perceived pain was assessed by visual analog scale, while pressure pain threshold (PPT) was verified by a digital algometer. Electromyographic evaluations (EMG) of anterior temporal and masseter muscles were also measured. All variables were assessed before and 1-month after therapies. The mixed-design two-way repeated measures ANOVA and Tukey’s post-hoc tests were used for analysis, considering a=0.05.Results Self-perceived pain decreased in all groups after one month of therapy (P<.001). BoNT-A was not better than AC in pain reduction (P=0.05), but both therapies were more effective in reducing pain than SS (P<0.05). BoNT-A was the only treatment able to improve PPT values (P<0.05); however, a severe decrease of EMG activity was also found in this group, which is considered an adverse effect.Conclusion after one month of follow-up, all therapies reduced the self-perceived pain in myofascial TMD patients, but only BoNT-A enhanced PPT yet decreased EMG.

Electromyographic evaluation of the masseter and temporalis muscles activity in patients with complete denture, implant supported and implant retained mandibular overdentures. a cross-over study

This study was conducted to compare the electromyographic [EMG] activity of both masseter and the anterior temporalis muscles in patients with: Conventional complete dentures, Implant supported overdentures without attachments and, Implant retained overdentures with locator attachments. Material and methods: Six completely edentulous male patients with atrophied mandibular ridges received upper and lower conventional complete denture. EMG activity were measured for both masseter and the anterior temporalis muscles during clenching without food, clenching hard (carrot) and soft (banana) foods. Measurements were made at time of denture insertion, one month and two months after. Two implants were installed in canine regions of the mandible. After osteointegration, healing abutments were connected and the mandibular denture were relined with hard acrylic resin. Measurements were repeated, then healing abutments were replaced with locator attachments, and measurements were repeated again. Results: The highest EMG activity/amplitude of masseter and temporalis muscles, were noted with locator overdentures, and the lowest values were observed with conventional dentures. There was no statistically difference in muscle activity between implant supported overdentures and complete dentures. For all groups, muscle activity for masseter and temporalis muscles increased with advance of time. For both groups, muscle activity was significantly higher during clenching of hard food than clenching without food or with soft food Conclusion: Within the scope of this study, implant retained overdentures are recommended for edentulous patients rather than conventional complete dentures or implant supported overdentures as it improves EMG activity/amplitude of masseter and temporalis muscles.

Masticatory muscle Activity in Individuals with Temporomandibular Disorder

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.

Adjustment of Occlusal Splint with Synchronized T-Scan III Digital Occlusal Analysis System and Bio-EMG III in a Patient with Sleep Bruxism

The occlusal splint has been frequently used as an effective treatment in sleep bruxism patients. In the adjustment procedure of occlusal splint with an optimal occlusion, clinicians usually use conventional methods; however, they cannot measure the surface area of contacts, amount of force, and contacting time sequence. Recently, two separate technologies have been synchronized together: T-Scan III and BioEMG III. In the present case report, an occlusal splint in a patient with sleep bruxism was adjusted with synchronized T-Scan computerized digital occlusal analysis system and BioEMG III. Optimal occlusal parameters were generated, and quantitative analyses of occlusal scheme and muscle activity level were performed before and after the adjustment of the occlusal splint. In the present case report, occlusion of the occlusal splint in a bruxism patient was adjusted with T-Scan III to fulfill the requirement of the optimal occlusion criteria. Before adjustment of occlusal splint, digital evaluation revealed unbalanced force distribution, lengthy occlusion (1.51 s), and disocclusion time (0.09 s) in centric relation. EMG activity of muscles was lower than expected values in centric relation. After adjustment of occlusal splint, canine protected occlusion with appropriate occlusion (0.2 s) and disocclusion (0.4 s) time were performed. Increased electromyography activity of the right anterior temporalis muscle showed a decrease in all excursive movements. Modern occlusal adjustment procedures provide a new standard of verification for the validation of occlusal splint fabrication with optimal occlusion.

Ultrasonographic observation of anterior temporalis and masseter muscle in open bite patients: A comparative study

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.

Changes in jaw and neck muscle coactivation and coordination in patients with chronic painful TMD disk displacement with reduction during chewing

The treatment of a complex temporomandibular disorder (TMD), such as disk displacement with reduction (DDR) associated with arthralgia and myalgia, may depends on understanding the impairments in muscle function. The aim of this study was to investigate the behavior of the anterior temporalis, masseter and sternocleidomastoid muscles in the time and frequency domains during chewing in patients with chronic painful TMD-DDR using electromyographic (EMG) analysis. Thirty-three patients who met the diagnostic criteria for TMD and 32 volunteers without TMD (control group) underwent clinical examination, chewing pattern classification and EMG analysis. For the EMG analyses, the side of habitual unilateral chewing, as determined by the chewing pattern classification, was selected for recording; in cases of bilateral chewing, the recording side was randomly selected. The EMG-EMG coherence function and EMG-EMG transfer function (gain and phase) values were obtained at the first chewing frequency peak, and the working-side masseter signal was used as a reference in the analyses of the other muscles. Compared to the control group, the TMD group showed a longer chewing stroke duration (P = 0.01) as well as changes in the coactivation and coordination strategies of the jaw muscles, evidenced by greater relative energy expenditure (P< 0.01) and impaired differential recruitment (P< 0.05) and coherence (P< 0.01). Delays in peak and temporal asynchrony occurred in the jaw and neck muscles (P< 0.05). Patients with chronic painful TMD-DDR during chewing presented changes in the jaw and neck muscles, with more compromised function of the former, which are specific to chewing.

Masticatory Dysfunction After Computed Tomography-Guided Plasma Ablation vs. Radiofrequency Ablation on Gasserian Ganglion for Idiopathic Trigeminal Neuralgia: A Randomized Controlled Trial.

We aimed to evaluate masticatory dysfunction after two different types of ablation on the Gasserian ganglion for the treatment of idiopathic trigeminal neuralgia. We hypothesized that low-temperature plasma radiofrequency ablation (LTP-RFA) was noninferior to radiofrequency thermocoagulation (RFT) with respect to initial efficacy. In the randomized, single-blind, parallel-group, noninferiority trial, 204 participants with idiopathic trigeminal neuralgia were randomly allocated to receive plasma ablation in the LTP-RFA group and radiofrequency ablation in the RFT group in a 1:1 ratio, with random block sizes of four or six. Participants were examined at baseline (T0), on the day of discharge (T1), and at the 6-month follow-up (T2). The primary end point was the clinincal effective rate in the LTP-RFA group compared with that in the RFT group after intervention on the day of discharge. Noninferiority was prespecified at -10%. The intention-to-treat analysis revealed that the initial efficacy rates were 91.2% in LTP-RFA group and 93.1% in RFT group (rate ratio [RR] = 0.979, 95% confidence interval [CI]: 0.904-1.061, P = 0.795). The difference between the two groups was 1.9% (95% CI: -5.6% to 9.4%), which showed that LTP-RFA demonstrated noninferiority compared with RFT in initial efficacy. Compared with the RFT group, the LTP-RFA group exhibited a significantly greater improvement in the maximum voltage of the masseter muscles with mean differences of 11.40 (95% CI: 10.52 to 12.27, P < 0.001) at T1 and 17.41 (95% CI: 14.68 to 20.13, P < 0.001) at T2, respectively. Similar results were observed for the asymmetry index of occlusion, the maximum voltage of the anterior temporalis, and the activity index of anterior temporalis/ masseter muscles. No serious adverse events were observed in either group. Compared with the RFT group, noninferior efficacy for pain relief and improvement of masticatory function was revealed in the LTP-RFA group.

Acute Effect of the Compression Technique on the Electromyographic Activity of the Masticatory Muscles and Mouth Opening in Subjects with Active Myofascial Trigger Points

Active myofascial trigger points (MTrPs) in masticatory muscles are associated with a reduced range of motion and muscle weakness within the stomatognathic system. However, it is hard to identify the most effective treatment technique for disorders associated with MTrPs. The objective of this study was to analyze the acute effect of the compression technique (CT) on active maximal mouth opening (MMO) and electromyographic activity of the masseter (MM) and temporalis anterior (TA) muscles in subjects with active myofascial trigger points in the MM muscles. The study group comprised 26 women (mean age 22 ± 2) with bilateral active myofascial trigger points (MTrPs) in the MM. The control group comprised 26 healthy women (mean age 22 ± 1) without the presence of MTrPs in the MM. Masticatory muscle activity was recorded in two conditions (during resting mandibular position and maximum voluntary clenching) before and after the application of the CT to the MTrPs in MM. After the CT application, a significant decrease in resting activity (3.09 μV vs. 2.37 μV, p = 0.006) and a significant increase in clenching activity (110.20 μV vs. 139.06 μV, p = 0.014) within the MM muscles were observed in the study group, which was not observed within TA muscles. Controls showed significantly higher active MMO values compared to the study group before CT (50.42 mm vs. 46.31 mm, p = 0.024). The differences between the study group after CT and controls, as well as among the study group before and after CT did not reach the assumed level of significance in terms of active MMO. The compression technique appears to be effective in the improvement of the active maximal mouth opening and gives significant acute effects on bioelectric masticatory muscle activity. Therefore, CT seems to be effective in MTrPs rehabilitation within the stomatognathic system.

Influence of Reported Physical Activity Level and Psychosocial Features on Orofacial Mechanical Sensitivity: A Pilot Study.

To evaluate the influence of self-reported physical activity level on painful mechanical somatosensory profile and psychosocial characteristics. A total of 90 participants, male and female, were divided into three groups based on the frequency, duration, and intensity of physical activity over the last 3 months. The classification followed a modified criterion of the short version of the International Physical Activity Questionnaire (IPAQ). Mechanical quantitative sensory tests were performed in the region of the anterior temporalis muscle and on the thenar area of the dominant hand, and psychosocial aspects were assessed using questionnaires measuring state and trait anxiety, pain catastrophizing, lifestyle, and quality of life. There was no significant main effect of group on any of the somatosensory variables (F < 0.34 and P > .416). As for psychosocial aspects, the low level of physical activity group had the lowest scores on the lifestyle questionnaire (P < .009). Level of physical activity did not significantly influence mechanical somatosensory thresholds or temporal summation in the orofacial region, and worse quality of life was found in participants reporting a low level of physical activity.

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

ABSTRACT 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.

Increased somatosensory amplification is associated with decreased pressure pain thresholds at both trigeminal and extra-trigeminal locations in healthy individuals.

The diagnosis of temporomandibular disorders (TMD) is based on patient history and physical examination, and may require medical imaging. Masticatory muscle palpation is essential to make a diagnosis of TMD. However, the response of masticatory muscles to mechanical pressure stimuli depends on many physical and psychological factors. This study aimed at determining the impact of somatosensory amplification (SSA)-an estimate of somatic awareness and bodily hypervigilance-on pressure pain thresholds (PPTs) measured at both trigeminal and extra-trigeminal locations in healthy individuals. PPTs were measured at the right anterior temporalis and superficial masseter, and the thenar eminence of the right hand in one hundred healhty individuals (69F, 31M), divided in three groups based on their SSA scores: low (N=32), intermediate (N=34) and high (N=34). General linear models were used to test between-group differences in PPTs including sex as a covariate. The level of significance was set at P<.05. Individuals with high SSA had lower PPTs at the anterior temporalis than individuals with low (P=.006) and intermediate (P=.001) SSA. No significant between-group differences were found in PPTs measured at the masseter (P=.372). PPTs measured at the thenar eminence were significantly lower in the high than the low SSA group (P=.009). Females had lower PPTs at the masseter than males (P=.021) but not at other muscle locations (all P>.05). Increased somatosensory amplification is associated with decreased pressure pain thresholds at both trigeminal and extra-trigeminal locations in healthy individuals. SSA could be a potential confounder while diagnosing TMD and evaluating treatment outcomes.

Longitudinal electromyographic changes in masseter and anterior temporalis muscle before and after temporomandibular joint arthroplasty in ankylosis patients

PurposeThe literature lacks evidence about activity of masseter and anterior temporalis muscles in temporomandibular joint ankylosis (TMJA) patients. The purpose of this study was to evaluate longitudinal electromyography (EMG) changes in masseter and anterior temporalis muscle before and after gap arthroplasty in unilateral TMJA patients. Specific aim was to investigate the EMG activity restoration to the level of non-ankylosed side after arthroplasty. MethodsThe investigator implemented a prospective longitudinal study amongst TMJA patients treated with gap arthroplasty. EMG of masseter and anterior temporalis were recorded bilaterally on ankylosed and non-ankylosed side. EMG signals of masseter and anterior temporalis were recorded preoperatively and 1 week, 3 month and 6 month postoperatively at rest and at maximum voluntary clench (MVC). ResultsThe study sample was composed of 16 (male:female = 1:1.28) unilateral TMJA patients. The mean duration of ankylosis was 3.25 ± 1.18 years. The difference in EMG root-mean-square (RMS) values of ankylosed side when compared to the preoperative values of non-ankylosed side was found to be statistically significant (p < 0.001) preoperatively, 1 week and 3 month postoperatively, while it was statistically not significant (p > 0.99) at 6-month postoperatively. ConclusionThe present study concludes that the TMJA patients have hyperactivity of masseter and anterior temporalis muscle. Restoring the function causes the muscle activity to progress to the values of normal side. EMG activity as measured on follow-up may be one of the predicting factor for re-ankylosis.

Effects of Chewing Exerciser on the Recovery of Masticatory Function Recovery after Orthognathic Surgery: A Single-Center Randomized Clinical Trial, a Preliminary Study.

Background and Objectives: The aim of this study was to evaluate the effects of the chewing exerciser (CE) on the functional recovery of the masticatory muscles after orthognathic surgery. Material and Methods: This randomized clinical trial was conducted in patients undergoing bimaxillary orthognathic surgery including bilateral sagittal split ramus osteotomy. Postoperative physiotherapy (PT) was performed for 3 weeks starting 3 weeks after the surgery. The patients were randomly divided into two groups: control (Con) (conventional PT) group and CE group (use of CE in addition to conventional PT). The masticatory function was evaluated based on three standards: bite force (BF), amount of mouth opening (MO), and surface electromyography (sEMG) of the anterior temporal muscle (TA), masseter muscle (MM), sternocleidomastoid muscle, and anterior belly of digastric muscle before, 3 weeks (before PT) and 6 weeks after the surgery (after PT). Results: Finally, 22 subjects participated in this study: 10 patients for Con group and 12 patients for CE group. In both groups, the BF, which was reduced significantly after the surgery, recovered after the PT similar to that before the surgery. In both groups, the MO was also significantly reduced by the surgery. However, it did not recover as much, as it was before the surgery after applying the PT. There was no difference in BF and MO between the two groups. All muscles did not show significant changes in sEMG by surgery and PT at both resting and clenching states. Conclusion: Applying CE as a PT after orthognathic surgery did not cause any harmful side effects. In both groups, the weakened muscle activity after orthognathic surgery (OGS) was adequately restored 6 weeks after the surgery. However, CE did not offer a statistically significant benefit to the masticatory function in the recovery process after OGS.

How Does a Unilateral Temporomandibular Joint Replacement Affect Bilateral Masseter and Temporalis Muscle Activity?—A Prospective Study

Total alloplastic temporomandibular joint replacement (TMJR) requires the detachment of the masseter muscle (MM) at its insertion to the lateral ramus and often the resection of the coronoid process (insertion of the temporalis muscle). There is little literature on how a detachment affects the muscles. The present study evaluates the long-term masticatory muscle activities and maximum voluntary bite force (MVC) in patients with unilateral TMJR. Surface electromyography of the MM and anterior temporalis muscle during bite force testing and MVC were evaluated bilateral preoperatively (T0), 1 (T3), 2 (T4), 3 (T5), and 4years (T6) postoperatively. The percentage overlapping coefficient (index of the symmetric distribution of muscular activity) was calculated. Differences between stock or custom devices were evaluated. Fourteen patients were enrolled, 4 males and 10 females, age 47.3±14.3years at TMJR placement. In 11 patients, the coronoid process was resected, 5 patients received stock, and 9 custom prostheses. After surgery, a trend in the improvement of bilateral surface electromyography activities and MVC was found without statistical significance for the side comparison or the time of the investigation. The percentage overlapping coefficient values showed postoperatively relative (>72%) symmetry in both muscles. Up to T5 on the TMJR side, MM showed higher activity when custom prostheses were used. There was no significant difference between stock and custom prostheses. The vertical (anterior) fibers of the temporalis muscle are preserved despite the resection of the coronoid process. The anterior temporalis muscle, as a synergist of the MM on the TMJR side, postoperatively partially assumes its abduction function. The detached MM appears to reattach. Generally, the bilateral increase in muscle activity and MVC of both muscles suggests regeneration of the investigated muscles. Custom prostheses seem to have an initial advantage for the reattachment of the MM compared with stock prostheses.

Effect of botulinum toxin treatment in patients with bruxism and orofacial pain - randomized double-blind clinical trial

Introduction: Bruxism is defined as a parafunctional chewing activity characterized by the clenching and / or grinding of teeth that occurs both during sleep and during the surveillance period. Methods: Thirty female patients between 18 and 40 years old who had bruxism and orofacial pain were selected and randomized into two groups: control group (n = 15), where individuals received 0.05 ml of sterile saline solution that was applied to the bundle anterior temporal muscles and 0.2 ml for each masseter muscle, and an experimental group (n = 15), individuals received 20 units of A-botulinum toxin (Botox®) applied to each masseter muscle and 5 units of A-botulinum toxin applied to the anterior bundle of each temporal muscle. Patients were called back for reevaluation every thirty days. At these moments, they underwent an evaluation of the load force and electromyography. Results: At 30, 60, 90 and 120 days, a decrease in electromyographic activity was observed in the A-botulinum toxin group (p &lt;0.001). In the experimental group, the left masseter muscle showed no significant difference between the variable load cell and time (p = 0.968), nor between electromyography versus load (p = 0.072), with a statistically significant difference between time and electromyography. (coef = 0.322; p &lt;0.001). Conclusion: The intramuscular application of botulinum toxin type A in patients with bruxism has proved to be an effective method for hyperactivity of the masseter muscle in patients with bruxism, improving and decreasing the levels of muscle contraction.

Evaluation of Masticatory Muscle Function Using Digital versus Traditional Techniques for Mockup Fabrication: A Controlled Prospective Study

Background: the aim of this longitudinal prospective study was to analyze the effect of digital and traditional mockup on masticatory muscle activity in patients with teeth wear, rehabilitated with an increase of occlusal vertical dimension. Subjects and Methods: a sample of 22 adult patients who were about to receive a prosthetic rehabilitation was divided into a study group (3M; 9F; mean age 42 ± 0.8 years), treated using the digital mockup; and a control group (2M; 8F; mean age 37 ± 0.5 years), treated using the conventional technique (traditional) mockup. Electromyographic activity of anterior temporalis and masseter muscles were evaluated before the beginning of the treatment (T0), at mockup insertion (T1), after treatment (T2) and each lapse of time lasted 2–5 months. Results: the comparison between the two groups at different time gaps revealed that at ∆1 (T1–T0) only the impact index (IMP) showed significant difference and no other significant variation was observed between the two groups at ∆2 (T2–T1) and ∆3 (T2–T0). It concludes that traditional and digital methods generally have nonsignificant differences. Conclusions: both methods seem to be effective in prosthetic rehabilitation and give comparable effects on masticatory muscles.

Biomechanical Design Application on the Effect of Different Occlusion Conditions on Dental Implants with Different Positions—A Finite Element Analysis

A dental implant is currently the most commonly used treatment for patients with lost teeth. There is no biomechanical reference available to study the effect of different occlusion conditions on dental implants with different positions. Therefore, the aim of this study was to conduct a biomechanical analysis of the impact of four common occlusion conditions on the different positions of dental implants using the finite element method. We built a finite element model that included the entire mandible and implanted seven dental implant fixtures. We also applied external force to the position of muscles on the mandible of the superficial masseter, deep masseter, medial pterygoid, anterior temporalis, middle temporalis, and posterior temporalis to simulate the four clenching tasks, namely the incisal clench (INC), intercuspal position (ICP), right unilateral molar clench (RMOL), and right group function (RGF). The main indicators measured in this study were the reaction force on the temporomandibular joint (TMJ) and the fixed top end of the abutment in the dental implant system, and the stress on the mandible and dental implant systems. The results of the study showed that under the occlusion conditions of RMOL, the dental implant system (113.99 MPa) and the entire mandible (46.036 MPa) experienced significantly higher stress, and the reaction force on the fixed-top end of the abutment in the dental implant system (261.09 N) were also stronger. Under the occlusion of ICP, there was a greater reaction force (365.8 N) on the temporomandibular joint. In addition, it was found that the reaction force on the posterior region (26.968 N to 261.09 N) was not necessarily greater than that on the anterior region (28.819 N to 70.431 N). This information can help clinicians and dental implant researchers understand the impact of different chewing forces on the dental implant system at different positions after the implantation.

Electromyographic Comparison of Lips and Jaw Muscles between Children With Competent and Incompetent Lips: A Cross Sectional Study.

This cross-sectional study evaluates the electromyographic (EMG) activity of lips and anterior temporalis muscles of children with competent or incompetent lips. Forty children were classified clinically according to their lip competence into two groups of 20 each: 1) competent lips group (CLG), and 2) incompetent lips group (ILG). Surface EMG activity of the superior orbicularis oris (SOO), inferior orbicularis oris (IOO), and anterior temporalis (AT) muscles was recorded with the children seated in the upright position during the following tasks: 1) at rest; 2) speaking; 3) swallowing; 4) puffing out the cheeks. ILG showed lower EMG activity than CLG in the SOO and IOO muscles at rest, similar activity in both muscles during speaking, similar activity in the SOO muscle and lower in the IOO during swallowing. ILG showed significantly higher activity than CLG in both muscles while puffing out the cheeks. In the AT muscle, ILG showed lower activity than CLG at rest, during speaking and swallowing, whereas activity was similar while puffing out the cheeks. The difference in EMG activity recorded in children with incompetent lips and with competent lips suggests that the status of their musculature could affect the position and stability of their upper/lower anterior teeth.

Role of inflammatory and pain genes polymorphisms in temporomandibular disorder and pressure pain sensitivity

ObjectiveThe aim of this study was to assess the correlation of inflammatory and pain genes polymorphisms with the presence of temporomandibular disorder (TMD) patients and with pressure pain sensitivity. DesignData was collected from 268 consecutive subjects at Bauru School of Dentistry. Subjects aged younger than 20 years, with dental and neuropathic pain, sinusitis, cognitive and neurologic disorder were excluded. Included subjects were evaluated using the Research Diagnostic Criteria for Temporomandibular disorders and divided into two groups: TMD cases and healthy controls. Groups were submitted to pressure pain threshold (PPT) test for the temporomandibular joint, anterior temporalis and masseter muscles and genotyped for Val158Met, IL6−174, IL-1β-3954 and TNFA-308. Student’s t-test and Pearson chi-square test were used to comparisons between groups. A linear multiple regression was used to evaluate the influence of genetics variables on the PPT and a bivariate analysis was used to assesses the influence of genetics variables on pain sensitivity below the PPT cut off of the structures in TMD group. ResultsTMD group showed significantly lower PPT values for all structures when compared with control group (p < 0.001). SNP IL6−174 predicted higher pain sensitivity in the temporomandibular joint (p < 0.005) and in anterior temporalis muscle (p < 0.044) and SNP Val158Met in the masseter muscle (p < 0.038); when TMD group was divided according to PPT cut-off values the SNP Val158Met influenced increase pain sensibility in the masseter muscle. ConclusionTNFA-308 was associated with TMD and SNP IL6−174 and SNP Val158Met influenced pain sensitivity of patients with TMD.

Biofotogrametric and electromyographic analysis in different position in women with temporomandibular disorder.

Introduction: The relationship established between TMJ (Temporomandibular Joint), cranium and cervical spine requires the synchrony of these structures for the proper performance of stomatognathic functions and muscle balance in this region. Objective: Evaluate the craniocervical posture and the electrical activity of masticatory and cervical muscles in sitting and standing positions in patients with TMD, correlating these variables. Method: The participants were 21 women, with mean age 28 ± 5.33 years and severe TMD. The participants were evaluated by electromyography of the masseter, anterior temporal and sternocleidomastoid (SCM) and upper trapezius muscles, bilaterally, in standing and sitting position. The body posture was evaluated by biophotogrammetry, with analysis of the Head Horizontal Alignment (HHA) and Acromion Horizontal Alignment (AHA) in frontal view and the Head Vertical Alignment (HVA) and Head Horizontal Alignment related to seventh cervical vertebra (HHAc7) in lateral view. Results: The electrical activity of masticatory muscles during resting did not differ between the different evaluated positions. During maximum intercuspation, the electrical activity was significantly lower in the left masseter (p=0.016), higher in the left anterior temporal muscle (p=0.046) and higher in the right (p=0.005) and left (p=0.015) upper trapezius muscles, in standing position when compared to sitting position. The photogrammetric values found were within the normal range. There was a significant and moderate negative correlation between the left SCM muscle and the right (r=0.386) and left (r=0.428) HHAc7 angle. Conclusions: Muscular electrical activity was modified with the change between sitting and standing positions, with an increase in cervical muscle recruitment and asynchrony of the masticatory muscles. Thus, it can be inferred that there is a postural destabilization with possible head anteriorization during maximum intercuspation, reinforcing the relation of synergy between the masticatory and cervical muscles.