Masseter Electromyographic Activity Research Articles

Effect of Hard and Soft Occlusal Splints on Electromyographic Activity of Masseter and Anterior Temporalis in Patients with Moderate to Severe Occlusal Wear: A Randomized Controlled Trial

Effect of Hard and Soft Occlusal Splints on Electromyographic Activity of Masseter and Anterior Temporalis in Patients with Moderate to Severe Occlusal Wear: A Randomized Controlled Trial

Orthodontic treatment of children with anterior open bite and posterior crossbite: An analysis of the stomatognathic system.

Dental malocclusions are deviations from normalities due to the inadequate growth and development of the dental arch which provides functional changes to the stomatognathic system. The aim of this longitudinal study was to evaluate the electromyographic activity (EMG) the masseter and temporalis muscles, strength of the orofacial tissues and occlusal force of children with anterior open bite (n=15) and posterior crossbite (n=20), 7 days after the removal of the orthodontic apparatus. A fixed horizontal palatal crib was used in the treatment of anterior open bite and the fixed appliances Hyrax or MacNamara was used in the treatment of posterior crossbite. EMG of the masticatory muscles was recorded using an electromyograph with wireless sensors during mandibular tasks. Habitual chewing was assessed using the integral of the linear envelope of the electromyographic signal in the masticatory cycles. The strength of the tongue and facial muscles was measured using the Iowa Oral Pressure Instrument. T-Scan was used to analyze the force of occlusal contact. Molar bite force was measured by digital dynamometer. Significant differences (p<0.05) were found in the EMG data of the masseter and temporalis muscles in the static and dynamic mandibular tasks. There were no significant difference in strength of orofacial tissues, occlusal contact force and molar bite force 7 days after the removal of the orthodontic apparatus. The results of this study suggest that the orthodontic treatment of anterior open bite and posterior crossbite in children promoted functional alteration in the electromyographic activity of masseter and temporalis muscles.

Electromyographic Analysis of Masticatory and Accessory Muscles in Subjects With Implant-Supported Fixed Prostheses: A Three-Arm Comparative Clinical Study.

Aim This study compares the electromyographic (EMG) activity of the masticatory and accessory muscles in patients with natural teeth and those wearing full-mouth fixed prostheses supported by implants. Method In this study, 30 subjects of 30-69 years performed static and dynamic EMG measurements of masticatory and accessory muscles (masseter, anterior temporalis, SCM, and anterior digastric) and were divided into three groups: Group 1 (G1, Control, Dentate), comprising 10 subjects with 14 or more natural teeth(30-51 years of age); Group 2 (G2, single arch implant-supported fixed prosthesis) composed of 10 patients with unilateral edentulism who were successfully rehabilitated with implant-supported fixed prostheses in the maxilla or mandible, restoring occlusion to 12-14 teeth per arch; (39-61 years of age); and Group 3 (G3, full mouth implant-supported fixed prosthesis) with10 subjects with completely edentulous arches with full mouth implant-supported fixed prosthesis with 12 occluding pairs of teeth (46-69 years of age). The left and right masseter, anterior temporalis, superior sagittal, and anterior digastric muscles were examined at rest, as well as maximum voluntary clenching (MVC), swallowing, and unilateral chewing. On muscle bellies, disposable, pre-gelled silver/silver chloride bipolar surface electrodes were parallel to muscle fibers. BIO-PAKeight® channels recorded electrical muscle activity (Bio-EMG III, BioResearch Associates, Inc. Brown Deer, WI). Results Full mouth embed upheld fixed prostheses patients had higher resting EMG activity than dentate and single curve implants. Full mouth embeds supported fixed prostheses and dentate patients had significantly different temporalis and digastric muscle mean EMG activity. Dentate people used their temporalis and masseter muscles more during the MVC than those with single-curve embedded upheld fixed prostheses limiting natural teeth or full-mouth implants. No event had the crucial item. Neck muscle differences were insignificant. All groups had higher SCM and digastric EMG activity during MVC than at rest. The single curve embed upheld fixed prosthesis group's temporalis and masseter muscles were significantly more active during gulping than the dentate and entire mouth groups. Single curve and entire mouth gulping SCM muscle EMG activity were similar. Digastric muscular EMG activity differed significantly between those with full-arch or partial-arch fixed prostheses and dentures. When instructed to bite one side, the masseter and temporalis front muscle mean EMG activity increased on the unrestricted side. Unilateral biting and temporalis muscle activation were comparable between groups. For the masseter muscle, the mean EMG was also higher on the functioning side, with no truly large differences between the three groups except for right-side biting when comparing the dentate and full mouth embed upheld fixed prosthesis groups and the single curve and full mouth groups. Conclusion The temporalis muscle activity difference was statistically significant in the full mouth implant-supported fixed prosthesis group.The three groups' static (clenching) sEMG analysis showed non-significant temporalis and masseter muscle activity increases. Full mouth swallowing increased digastric muscle activity. All three groups had similar unilateral chewing muscle activity except for the working side masseter muscle.

Longitudinal changes in electromyographic activity of masseter and anterior temporalis muscles before and after alloplastic total joint replacement in patients with temporomandibular ankylosis: a prospective study

The purpose of the study was to evaluate the longitudinal changes in electromyographic (EMG) activity of the masseter and temporalis muscles before and after temporomandibular joint (TMJ) total joint replacement (TJR) in ankylosis patients. A prospective longitudinal study was designed on patients undergoing unilateral or bilateral TMJ-TJR. EMG activity at rest and maximal voluntary contraction (MVC) was recorded for the muscles preoperatively (T0), and at one-week (T1) and six-month (T2) follow up. The study sample was composed of 10 (male: female 2.3:1) patients undergoing TMJ-TJR. The number of unilateral and bilateral cases was three and seven, respectively. In both unilateral and bilateral cases a statistically significant reduction in EMG activity of the masseter and anterior temporalis muscles was observed at T1. At T2, EMG activity of the muscles was found to be approaching the preoperative value. In unilateral cases, when the affected side at T0, T1, and T2 was compared with T0 for the unaffected side, statistically significant differences were seen for the masseter. In the case of the temporalis, similar results were seen except at T2 for the postural rest position. The results indicate that re-attachment of the masseter and temporalis muscles occurs progressively post TMJ-TJR.

Electromyographic activity of the masseter muscle in individuals with group function and canine guidance.

Background. There is no general consensus in restorative dentistry about which lateral guidance should be established. Some studies have shown that canine guidance decreases the tension of masticatory muscles. Others have reported that group function might achieve a better physiologic distribution of occlusal forces. Also, some reports have shown that both guidances are equally acceptable. Despite all discussions, clinical evidence of one guidance being superior to another is limited. Thus, this study aimed to analyze the electromyographic (EMG) activity of masseter muscles in individuals with group function and canine guidance. Methods. Twenty volunteers of both genders, aged 20-25, were divided into two groups: GF (group function guidance, n=10) and CA (canine guidance, n=10). EMG activity of masseters was captured using surface electrodes during habitual maximum intercuspation (HMI) and right and left lateral jaw movements and recorded using EMG amplitude values (RMS – root means square). Student’s t-test was used to compare mean RMS values between the groups and lateral movements in each group. Results. During HMI, there was no difference in masseter EMG activity between the groups. Both masseters showed higher activity in group GF only on the right side during lateral movements, while the left masseter exhibited higher activity on the nonworking side in both groups. The activity of both masseters distributed by tooth was higher in group CA. Conclusion. During tooth restorative procedures, any guidance is acceptable considering HMI. However, group function guidance is more favorable during lateral movements due to greater dissipation of occlusal pressures.

Effects of vibratory feedback stimuli through an oral appliance on sleep bruxism: a 6-week intervention trial

Various biofeedback stimulation techniques of managing sleep bruxism (SB) have recently emerged; however, the effect of successive application of vibratory feedback stimulation has not been clarified. This study elucidated the effect of vibration feedback stimulation via an oral appliance (OA) on SB when vibration feedback was applied for 4weeks. This was a prospective, single-arm, open-label, intervention study. Ten participants diagnosed with "definite" SB wore a specially designed OA for 45 nights in a home-setting. A force-based SB detection system, including a pressure-sensitive piezoelectric film placed internally in the OA, triggered a vibrator attached to the OA. Vibratory stimulation was withheld during the first 2-week adaptation period (1st-15th nights), applied during the 4-week stimulation period (16th-43rd nights), and again withheld during the post-stimulation period (44th and 45th nights). The number and duration of SB episodes/hour of sleep were calculated based on masseter electromyographic activity recorded with in-home portable polysomnography and compared between the 15th and 45th nights (without stimulation) and the 17th and 43rd nights (with stimulation). The number and duration of SB episodes significantly decreased after vibratory stimulation (15th vs. 17th nights: p = 0.012 and p = 0.012, respectively), then significantly increased upon cessation of vibratory stimulation after the stimulation period (43rd vs. 45th nights: p = 0.023 and p = 0.023, respectively). Contingent vibratory stimulation through an OA may suppress SB-related masticatory muscle activity continuously for 4weeks and may be an effective alternative for the management of SB. https://jrct.niph.go.jp/ ; trial registration number: jRCTs032190225.

Effect of contingent vibratory stimulus via an oral appliance on sleep bruxism after the splint adaptation period

Contingent vibratory feedback stimuli applied by a specially designed oral appliance (OA) have been reported to be effective in reducing sleep bruxism (SB). However, the inhibitory effects of the OA, which occur immediately after OA delivery, may have confounded this finding. This study sought to shed light on the effects of vibratory stimuli on SB after the OA adaptation period, when its inhibitory effects are diminished. Fourteen 'definite' SB patients were enrolled. A force-based bruxism detection system was utilised to trigger a vibrator attached to the OA. Masseter electromyographic activity during sleep was recorded at home using portable polysomnography. After using the OA without vibratory stimulus for 16 nights (adaptation period), intermittent vibratory stimuli were applied every other half-hour for four nights (intervention period). Electromyographic activity over 10% of the maximum voluntary contraction was regarded as a SB episode. The number and the total duration of SB episodes per hour of sleep were calculated for the sessions with and without stimuli separately and averaged for four intervention nights. The effects of stimuli on these two variables were evaluated. The number and the total duration of the sessions without stimuli were 5.2episodes/h and 35.3s/h, respectively. These values significantly decreased to 3.9episodes/h and 15.1s/h (p<.05) for the sessions with vibratory stimuli. Contingent vibratory stimulus via an OA may be effective for the management of SB even after adaptation to OA.

Effects of Carbonation and Temperature on Voluntary Swallowing in Healthy Humans.

We investigated how swallowing behaviors are affected by the temperature and carbonation of water in healthy humans. Twenty-nine healthy volunteers were instructed to drink as much natural water, carbonated water, or cider as they wanted, and we recorded the volume of solution swallowed and electromyographic (EMG) activity of the masseter and suprahyoid muscles. Sensory tests regarding the ease of holding the solution in the mouth and ease of swallowing were also performed. The volume of carbonated water swallowed was significantly lower than that of natural water and cider. The ease of holding and swallowing the solution significantly differed between solution types such that natural water was the easiest solution to hold and swallow, followed by cider and then carbonated water in both tests. EMG activity was also affected by the solution type. Masseter EMG activity was significantly lower when swallowing natural water compared with carbonated water. Suprahyoid EMG activity was significantly lower when swallowing natural water compared with carbonated water and cider. The volume of solution swallowed was significantly correlated with the ease of holding and swallowing the solution, but not with masseter or suprahyoid EMG activities. The ease of holding and swallowing the solution significantly affected masseter and suprahyoid EMG activities. The results suggested that when participants experienced difficulty holding and swallowing the solution, masseter and suprahyoid EMG activity increased. Considering our findings that mechanical stimulation with bubbles decreased the volume of solution swallowed and increased EMG activities, carbonated water swallowing may be useful in treating deglutition disorders.

Peripherally Physiological Responses to External Emotions and Their Transitions in Bipolar I Disorder With and Without Hypersexuality.

Hypersexuality is associated with psychiatric disorders such as mania; however, it remains unclear whether bipolar I disorder with (BW) or without (BO) hypersexuality demonstrates different responses to external emotional stimuli and their transitions that were composed of pictures and sounds of same domain. In 21 BW patients, 20 BO patients, and 41 healthy volunteers, we administered polygraph tests (electrocardiogram, electromyogram, electrooculogram, and galvanic skin response) to measure transitions from a primer emotion (i.e., external disgust, erotica, fear, happiness, neutral, and sadness) to a noncongruent emotion (out of the remaining five) and to the primer emotion again (repeat-primer). We also evaluated participants' concurrent states of mania, hypomania, and depression. With neutral as the noncongruent emotion, the heart rate difference in BW was greater than in controls when responses to the primer erotica were subtracted from responses to the repeat-primer erotica, or when to the primer sadness were subtracted from the repeat-primer sadness. The difference of the masseter electromyographic activity in BW was lower than in BO and controls when responses to the noncongruent happiness were subtracted from responses to the repeat-primer neutral, and was lower than in BO when to the noncongruent neutral were subtracted from the repeat-primer erotica. The eyeball movement difference was greater in BW than in BO and controls when responses to the noncongruent sadness were subtracted from responses to the repeat-primer neutral. The heart rate difference when responses to the primer happiness were subtracted from responses to the noncongruent neutral was negatively correlated with mania in BO. BW and BO patients behaved differently to external emotions and their transitions, particularly regarding erotica and sadness, which might characterize unique pathophysiological processes of the two bipolar I disorder subtypes.

Is there a difference in the electromyographic activity of the masticatory muscles between individuals with temporomandibular disorder and healthy controls? A systematic review with meta‐analysis

The diagnosis of temporomandibular disorders (TMD) is complex, and it is not yet clear in the literature whether the clinical changes associated with these disorders are also reflected in the electromyographic (EMG) activity of the muscles of mastication. To determine whether there is a difference in the electromyographic activity of the masticatory muscles between individuals with TMD and healthy controls. ScienceDirect, EMBASE, MEDLINE, PEDro, SciELO, CINAHL and LILACS databases from January 2000 to February 2019. Cross-sectional studies, crossover studies and randomised controlled trials evaluating EMG activity of right and left masseter and anterior temporal muscles in patients with TMD and healthy controls. Two independent assessors extracted data from the selected articles. The risk of bias was determined using a checklist for assessing methodological quality created based on the guidelines of the Strengthening the Reporting of Observational Studies in Epidemiology and International Society of Electrophysiology and Kinesiology. Mean differences and 95% confidence intervals were calculated and combined in meta-analyses. A total of 51267 studies were retrieved, and 12 were included in this review. Only two studies enabled the comparative analysis of the results. The different EMG signal capturing, processing and analysis methods used constitute an important limitation to the comparative analyses of the results reported in the studies selected for the present review. This systematic review did not demonstrate evidence of significant differences in the EMG activity of the masticatory muscles between individuals with TMD and healthy controls.

Impact of chronic allergic rhinitis on bite force and electromyographic activity of masseter and temporalis muscles of adult women.

BackgroundThe aim of this study was to analyse the stomatognathic system of adult women with chronic allergic rhinitis by means of molar bite force and electromyographic activity of the masseter and temporalis muscles. Material and MethodsA total of 26 subjects were screened and divided into two distinct groups: chronic allergic rhinitis group (n = 13) and healthy control group (n = 13). Subjects were assessed by maximal molar bite force (right and left) and normalized electromyographic activity of mandibular tasks (rest, right and left laterality, protrusion and maximal voluntary contraction). Data were submitted to Student’s t test (p< .05). ResultsThere was significant difference in right (p = .03) and left (p = .04) maximal molar bite force with force reduction in the chronic allergic rhinitis group. There was significant difference in normalized electromyographic activity in maximal voluntary contraction in the right (p =.01) and left (p = .01) temporalis muscles, with increased electromyographic activity in the masticatory muscles for the chronic allergic rhinitis group. ConclusionsThe results suggest that chronic allergic rhinitis in adult women promoted negative changes in the electromyographic activity of temporalis muscles in maximal voluntary contraction and maximal molar bite force. Key words:Rhinitis, occlusal force, electromyography, masticatory muscles.

Effects of different deprogramming devices on electromyographic activity of masseter and temporalis muscles: A crossover clinical study

Effects of different deprogramming devices on electromyographic activity of masseter and temporalis muscles: A crossover clinical study

EMG COMPARISON BETWEEN MASTICATORY MUSCLES WHEN USING NARROW DIAMETER IMPLANT ASSISTED MANDIBULAR OVERDENTUES

INTRODUCTION: One of the primary objectives of complete dentures is to restore masticatory function in people who have lost their natural teeth. Patients wearing conventional complete denture (CD) often complain of instability of the mandibular denture leading to a feeling of insecurity, inefficient mastication, and overall dissatisfaction with the prosthesis. Implant mandibular overdentures (IOD) constitute a secure therapeutic alternative, affording a great patient’s satisfaction and masticatory efficiency. The most common problem in implant dentistry is the presence of insufficient bone volume to receive the conventional size of dental implants. The 2-pieces narrow diameter implants were introduced into the market combining the undisturbed healing period required for proper osseointegration and the avoidance of time, cost and morbidity of extensive surgeries for bone augmentation. OBJECTIVES: The aim of the current work was to evaluate and compare the electromyographic (EMG) activity of masseter and anterior temporalis muscles when using three different treatment protocols i.e. (conventional CDs, two and four IODs). MATERIALS AND METHODS: Eight completely edentulous patients were selected from the prosthetic department, Faculty of dentistry, Alexandria University. Implant mandibular assisted overdentures were constructed for each patient using narrow diameter implants and delayed loading protocol. EMG activity of masseter and anterior temporalis muscles during habitual chewing and maximal voluntary clenching were recorded for each of the studied patients in the three different treatment protocols. RESULTS: EMG activity of masseter and anterior temporalis muscles of IOD was significantly lower with conventional CD than with IOD. Patients with four IOD showed higher EMG activity of masticatory muscles and better function compared to two IOD. Masticatory muscles activity during clenching was significantly higher than during chewing. CONCLUSIONS: It was concluded that IODs have great masticatory efficiency when compared to CD. Implants number affect masticatory efficiency and muscle activity in cases of severely resorbed mandibular ridge.

Correlación entre la actividad muscular masetera y la fuerza máxima de mordida entre varios patrones de divergencia facial

Objective: To comparatively assess electromyographic (EMG) activity of masseter muscle and maximum bite force among various facial divergence pattern. To compare bilateral variation therefore derive the clinical importance changes in masseter EMG activity. Materials and Methods: The sample size comprised of 90 subjects, age ranging from 16-25 years. They were further classified under three subgroups-normodivergent, hypodivergent and hyperdivergennt based on the cephalometric values. Tekscan Flexiforce B201H sensor along with the associated software was used to record the bite force. The EMG of the superficial masseter muscle was recorded using Biotech Neurocare 2000 surface electromyography machine. The muscle activity was recorded bilaterally from the superficial masseter. The data obtained were statistically analyzed using ROC curve at p&lt;0.05. Results: The bite force of the Hypodivergent group (571.83N±36.65) was more than the Normodivergent (387.26±27.20) and Hyperdivergent groups (373.21N±29.23). The EMG recording of masseter muscle activity in Hypodivergent group was significantly higher than Normodivergent and Hyperdivergent groups. (p-value= &lt;0.01). A significant correlation existed between masseter activity and bite force. Conclusion: The bite force of Hypodivergent jaw base individuals is highest followed by Normodivergent and least in Hyperdivergent individuals.The strong correlation between the muscular activity and the bite force is definitely a contributor to the anchorage value during treatment by fixed Orthodontics.

Effect of Different Denture Base Material on Electromyographic Activity in Maxillary Single Denture Wearers

Aim of study: was to evaluate and compare the effect of three different denture base material (heat cured acrylic resin, cast metal base and thermoplastic resin) on electromyographic activity of masseter and temporalis muscles in maxillary single denture wearers. Material and methods: Ten completely maxillary edentulous patients were selected with ages ranged from 55-60 years. All patients had received heat cured acrylic resin single maxillary complete denture (Group І) then replacing the denture base through rebasing procedures by cobalt chromium (Co-Cr) (Group ІІ) then thermoplastic resin material (Group ІІІ). All patients were instructed to use their resin dentures for equal periods of three months when EMG records of muscles of mastication (masseter and temporalis) were obtained at insertion then patient recalled after one month and at the end of three months , period of two week interval was left between each group as a washing period. Results: The results of this study showed that there were a significant differences between them, as the thermoplastic resin (group ІІІ) was the best followed by cobalt chromium denture (group ІІ) then heat cured acrylic resin denture base (group І) .Conclusion: EMG activity affected by maxillary denture base material as the lesser effort of masticatory muscles was done by using thermoplastic resin denture base rather than Co-Cr or acrylic resin denture base.

Electromyographic activity changes of jaw-closing muscles in patients with different occlusion schemes after fixed prosthetic restoration

Background/Aim: To investigate the electromyographic (EMG) activity changes of jaw-closing muscles in patients with different occlusion schemes and posterior edentulous span, after the placement of teethsupported fixed partial denture (FPD). Material and Methods: The study sample consisted of 20 patients (10 men and 10 women, the mean age being 50 years) with a posterior edentulous area that includes two missing premolars or one premolar and one molar. The participants were divided into two groups with different occlusion schemes: canine-guided occlusion (CGO) and group function occlusion (GFO). The metal-ceramic FPD were fabricated according to the clinic-standardized protocol. EMG activities of masseter and anterior temporalis patients' muscles were recorded with bipolar surface electrodes during maximal voluntary clenching. EMG evaluation was repeated twice: (T1) before the fabrication of FPD (T2) after eight weeks of FPD cementation and intraoral functioning of restoration. The data were subjected to Analysis of Variance-ANOVA within the methodological framework of the General Linear Models with Repeated Measures. The Bonferroni test was used to compare multiple mean measures. Statistical analysis was conducted with SPSS ver. 11.5. The level of significance was predefined at a=0.05. Results: Group 1 with CGO presented significantly higher levels of masseter (mean maximum EMG average before 79.36μV and 139.68μV after) and temporalis (mean maximum EMG average before 79.07μV and 149.37μV after) EMG activity after FPD placement. Group 2 with GFO also showed significantly higher levels of masseter (mean maximum EMG average before 61.57μV and 165.30μV after) and temporalis (mean maximum EMG average before 56.94μV and 133.08μV after) EMG activity after the prosthetic restoration. Conclusions: It may be concluded that fixed prosthetic restoration, in both patients with canine-guided and group function occlusion, results in increased EMG jaw-muscle activity.

Temporomandibular dysfunction, myofascial, craniomandibular and cervical pain: effect on masticatory activity during rest and mandibular isometry

ABSTRACT BACKGROUND AND OBJECTIVES: Craniomandibular and cervical symptoms interfere with mandibular stability. Determining whether these disorders influence muscle activation when chewing, it is possible to improve interventions for this population. The objective of this study was to verify the effect of the temporomandibular joint dysfunction, craniomandibular and cervical pain on the electromyographic activity of the masticatory muscles during rest and mandibular isometry. METHODS: Fifty-five women aged between 18 and 30 years were divided into two groups: with temporomandibular dysfunction (n=28) and without temporomandibular dysfunction (n=27). The diagnosis of temporomandibular dysfunction was established using the Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD). The RDC was also used to determine the presence of craniomandibular pain. Cervical pain was defined by physical examination. The electromyographic activity of masseter and temporalis muscles was evaluated in the rest position and mandibular isometry. The amplitude of muscle activation was represented by the root mean square values (RMS%) and normalized by maximum voluntary contraction. The Mann-Whitney U test was used to detect differences between the groups with and without temporomandibular dysfunction; with and without myofascial craniomandibular pain; and with and without cervical myofascial pain. RESULTS: It was observed greater amplitude in the activation of masseter and right temporalis muscles in the rest position in individuals with myofascial craniomandibular pain compared to asymptomatic (p<0.05). There was no difference among individuals with and without cervical myofascial pain, and with and without temporomandibular dysfunction. CONCLUSION: The presence of myofascial craniomandibular pain did not affect the masticatory activity, with greater muscle activation in mandibular rest.

Masticatory muscle activity evaluation by electromyography in subjects with zygomatic implants.

BackgroundZygomatic implants are an alternative treatment in the rehabilitation of atrophic maxilla to promote stability in the stomatognathic system. The aim of this study was to compare the electromyographic (EMG) activity of masseter and temporalis muscles in controls and in individuals with complete implant-supported dentures anchored in the zygomatic bone.Material and MethodsFifty-four volunteers of both genders (mean age 52.5 years) were selected and distributed into two groups: Individuals with zygomatic implant (ZIG; n=27) and fully dentate patients (CG; n=27). MyoSystem-BR1 was used to assess masseter and temporalis muscles EMG activity in different mandibular movements: protrusion, clenching, maximal voluntary contraction (MVC) with Parafilm M®, right and left laterality and chewing (peanuts and raisins). Data was processed, normalized (MVC) and analyzed using the SPSS 21.0. Student t-test (P ≤ 0.05) was used for group comparison.ResultsThe results were statistically significant (P ≤ 0.05) for protrusion, clenching, right and left laterality and raisin chewing. For the mandibular posture conditions, the ZIG obtained higher EMG activity patterns when compared to CG. For the masticatory performance during chewing of peanuts and raisins, the ZIG showed higher EMG mean values when compared to CG.ConclusionsThe zygomatic implant promoted an active response of the muscle fibers (hyperactivity) during both mandibular posture and chewing conditions, probably due to the absence of periodontal receptors, which play a significant role for preparing a bolus for swallowing. Key words:Zygomatic implant, electromyography, masseter muscle, temporal muscle.

Fine motor control of the jaw following alteration of orofacial afferent inputs

ObjectiveThe study was designed to investigate if alteration of different orofacial afferent inputs would have different effects on oral fine motor control and to test the hypothesis that reduced afferent inputs will increase the variability of bite force values and jaw muscle activity, and repeated training with splitting of food morsel in conditions with reduced afferent inputs would decrease the variability and lead to optimization of bite force values and jaw muscle activity.Material methodsForty-five healthy volunteers participated in a single experimental session and were equally divided into incisal, mucosal, and block anesthesia groups. The participants performed six series (with ten trials) of a standardized hold and split task after the intervention with local anesthesia was made in the respective groups. The hold and split forces along with the corresponding jaw muscle activity were recorded and compared to a reference group.ResultsThe hold force and the electromyographic (EMG) activity of the masseter muscles during the hold phase were significantly higher in the incisal and block anesthesia group, as compared to the reference group (P < 0.001). However, there was no significant effect of groups on the split force (P = 0.975) but a significant decrease in the EMG activity of right masseter in mucosal anesthesia group as compared to the reference group (P = 0.006). The results also revealed that there was no significant effect of local anesthesia on the variability of the hold and split force (P < 0.677). However, there was a significant decrease in the variability of EMG activity of the jaw closing muscles in the block anesthesia group as compared to the reference group (P < 0.041), during the hold phase and a significant increase in the variability of EMG activity of right masseter in the mucosal anesthesia group (P = 0.021) along with a significant increase in the EMG activity of anterior temporalis muscle in the incisal anesthesia group, compared to the reference group (P = 0.018), during the split phase.ConclusionsThe results of the present study indicated that altering different orofacial afferent inputs may have different effects on some aspects of oral fine motor control. Further, inhibition of afferent inputs from the orofacial or periodontal mechanoreceptors did not increase the variability of bite force values and jaw muscle activity; indicating that the relative precision of the oral fine motor task was not compromised inspite of the anesthesia. The results also suggest the propensity of optimization of bite force values and jaw muscle activity due to repeated splitting of the food morsels, inspite of alteration of sensory inputs.Clinical relevanceSkill acquisition following a change in oral sensory environment is crucial for understanding how humans learn and re-learn oral motor behaviors and the kind of adaptation that takes place after successful oral rehabilitation procedures.

A randomised, open-label, crossover study of the dopamine agonist, pramipexole, in patients with sleep bruxism.

Sleep bruxism bears several similarities to restless legs syndrome, and a link to changes in central dopamine activity has been considered in both conditions. The dopamine agonist pramipexole is currently indicated for the symptomatic treatment of restless legs. The effect of pramipexole on sleep bruxism was investigated in subjects with 'probable bruxism' recruited at the Orofacial Pain Clinic. Thirteen patients underwent polysomnographic recordings, including bilateral masseter electromyographic activity. Following habituation to the recording equipment, a baseline registration was used to confirm bruxism [total episodes per hour, mean 11.3 (6.3)]. Following randomisation, subjects received no treatment or pramipexole titrated from 0.09 to 0.54mg, o.d., for 3weeks according to a crossover procedure. A polysomnographic-electromyographic registration was performed at the end of each period. Pramipexole was associated with more frequent awakenings and a reduction in rapid eye movement sleep (both P≤0.02). Sleep apnea decreased marginally after pramipexole (apnea-hypopnea index 17.1 compared with control 21.5, P≤0.05). The number of bruxism episodes, phasic, tonic and mixed per hour, remained unchanged after pramipexole [total episodes per hour 12.7 (8.5) and 9.8 (5.2) during pramipexole and control conditions, respectively]. It is concluded, from this pilot study, that sleep bruxism is not affected by the dopaminergic agent, pramipexole.