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Masticatory Muscles (masticatory + muscle)
Selected AbstractsRegenerative potential of human skeletal muscle during agingAGING CELL, Issue 2 2002Valérie Renault Summary In this study, we have investigated the consequences of aging on the regenerative capacity of human skeletal muscle by evaluating two parameters: (i) variation in telomere length which was used to evaluate the in vivo turn-over and (ii) the proportion of satellite cells calculated as compared to the total number of nuclei in a muscle fibre. Two skeletal muscles which have different types of innervation were analysed: the biceps brachii, a limb muscle, and the masseter, a masticatory muscle. The biopsies were obtained from two groups: young adults (23 ± 1.15 years old) and aged adults (74 ± 4.25 years old). Our results showed that during adult life, minimum telomere lengths and mean telomere lengths remained stable in the two muscles. The mean number of myonuclei per fibre was lower in the biceps brachii than in the masseter but no significant change was observed in either muscle with increasing age. However, the number of satellite cells, expressed as a proportion of myonuclei, decreased with age in both muscles. Therefore, normal aging of skeletal muscle in vivo is reflected by the number of satellite cells available for regeneration, but not by the mean number of myonuclei per fibre or by telomere lengths. We conclude that a decrease in regenerative capacity with age may be partially explained by a reduced availability of satellite cells. [source] No effect of experimental occlusal interferences on pressure pain thresholds of the masseter and temporalis muscles in healthy womenEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2006A. Michelotti It has been suggested that occlusal interferences may lead to pain and tenderness of the masticatory muscles. Tender jaw muscles are more sensitive to pressure pain, as assessed by means of pressure algometry. We tested the effects of occlusal interferences on the pressure pain threshold of the jaw muscles by means of a double-blind randomized crossover experiment carried out on 11 young healthy females. Golden strips were glued either to an occlusal contact area (active interference) or to the vestibular surface of the same tooth (dummy interference) and left for 8 d each. Pressure pain thresholds of the masseter and anterior temporalis muscles were assessed under interference-free, dummy-interference and active-interference conditions. The results indicated that the application of an active occlusal interference, as used in this study, did not influence significantly the pressure pain thresholds of these muscles in healthy individuals. [source] Masticatory performance in patients with anterior disk displacement without reduction in comparison with symptom-free volunteersEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2002Ingrid Peroz Masticatory function can be impaired by craniomandibular disorders. The aim of this study was to assess masticatory performance in patients with an anterior disc displacement (ADD) without reduction. In the experiments, 29 patients and 33 age- and gender-matched volunteers chewed artificial test food for 60 chewing strokes. The collected remains of the test food were filtered, dried, fractionated by a sieving procedure, and weighed. The particle size distribution was then described using a cumulative distribution function. Patients and controls were clinically examined, and patients were asked to complete a pain questionnaire. Comparison with controls, patients showed significantly reduced masticatory performance. Patients that had had a disorder longer than 3 yr tended to display less reduction of their masticatory performance. Neither the treatment methods used, nor restriction of daily life activities or pain intensity were significantly correlated with masticatory performance. Jaw mobility was significantly reduced in patients. More than half of the patients and none of the controls had joint noises and trigger points in the masticatory muscles. Pain was present, in particular, during chewing and maximal opening of the mouth. It was concluded that patients with ADD without reduction have a significantly reduced masticatory performance. [source] Task-related electromyographic spectral changes in the human masseter and temporalis musclesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2002Mauro Farella The masticatory muscles differ in their fiber type composition. It can therefore be expected that their electromyographic (EMG) power spectra will differ during the performance of different bite force tasks. In the present study, surface EMG activity was picked up from the masseter and from the anterior and posterior temporalis muscles of nine adult subjects. At a bite force level as low as 25 N, the mean power frequency (MPF) values of the posterior temporalis were significantly lower than those of the masseter and anterior temporalis. The MPF values of the masseter muscles decreased with an increase of bite force magnitude, whereas the MPF values of the anterior and posterior temporalis did not change significantly. The MPF values were significantly influenced by the direction of bite force. The observed changes of MPF are possibly related to the recruitment of different fiber types, and support the concept that the masticatory muscles behave heterogeneously. [source] Effects of prolonged gum chewing on pain and fatigue in human jaw musclesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2001Mauro Farella Gum chewing has been accepted as an adjunct to oral hygiene, as salivary stimulant and vehicle for various agents, as well as for jaw muscle training. The aim of this study was to investigate the effects of prolonged gum chewing on pain, fatigue and pressure tenderness of the masticatory muscles. Fifteen women without temporomandibular disorders (TMD) were requested to perform one of the following chewing tasks in three separate sessions: chewing a very hard gum, chewing a soft gum, and empty-chewing with no bolus. Unilateral chewing of gum or empty chewing was performed for 40 min at a constant rate of 80 cycles/min. In each session, perceived muscle pain and masticatory fatigue were rated on visual analog scales (VAS) before, throughout, and after the chewing task. Pressure pain thresholds (PPTs) of masseter and anterior temporalis muscles were assessed before and immediately after the chewing tasks, and again after 24 h. The VAS scores for pain and fatigue significantly increased only during the hard gum chewing, and after 10 min of recovery VAS scores had decreased again, almost to their baseline values. No significant changes were found for PPTs either after hard or soft gum chewing. The findings indicate that the jaw muscles recover quickly from prolonged chewing activity in subjects without TMD. [source] Adaptation of normal and hypofunctional masseter muscle after bite-raising in growing ratsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2000Andrea Bresin The aim of this study was to analyze the effects of prolonged muscular elongation induced by bite-raising on the length of the muscle belly, sarcomeres and aponeurosis of the anterior deep masseter in the growing rat. Another aim was to determine the role of different functional conditions of this muscle in the adaptation process. Ninety-six young male rats were split into two groups: one was fed a hard diet and the other a soft diet to develop different functional capacities in the masticatory muscles. After 2 wk, half of the rats in both groups were fitted with an appliance that raised the bite by 2 mm. The measurements on the muscles were performed in situ. The insertion of the appliance stretched the anterior masseter muscle. After 4 wk, the vertical dentoskeletal dimension, the muscle belly, and the sarcomeres showed no difference in length among the groups. However, the aponeurosis was longer in the rats wearing the appliance compared to the controls, and among the bite block groups it was longer in the rats fed a hard diet. Length adaptation occurred in the aponeurosis. Clinically this may imply a need for reactivation of functional appliances to increase their efficiency, at a rate possibly depending on masseter muscles functional condition. [source] Bone repair in mandibular body osteotomy after using 2.0 miniplate system , histological and histometric analysis in dogsINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 2 2008Cássio Edvard Sverzut Summary The objective of this study was to evaluate the bone repair along a mandibular body osteotomy after using a 2.0 miniplate system. Nine adult mongrel dogs were subjected to unilateral continuous defect through an osteotomy between the mandibular 3rd and 4th premolars. Two four-hole miniplates were placed in accordance with the Arbeitgeimeinschaft für Osteosynthesefragen Manual. Miniplates adapted to the alveolar processes were fixed monocortically with 6.0-mm-length titanium alloy self-tapping screws, whereas miniplates placed near the mandible bases were fixed bicortically. At 2, 6 and 12 weeks, three dogs were sacrificed per period, and the osteotomy sites were removed, divided into three thirds (Tension Third, TT; Intermediary Third, IT; Compression Third, CT) and prepared for conventional and polarized light microscopy. At 6 weeks, while the CT repaired faster and showed bone union by woven bone formation, the TT and IT exhibited a ligament-like fibrous connective tissue inserted in, and connecting, newly formed woven bone overlying the parent lamellar bone edges. At 12 weeks, bone repair took place at all thirds. Histometrically, proportions of newly formed bone did not alter at TT, IT and CT, whereas significantly enhanced bone formation was observed for the 12-week group, irrespective of the third. The results demonstrated that although the method used to stabilize the mandibular osteotomy allowed bone repair to occur, differences in the dynamics of bone healing may take place along the osteotomy site, depending on the action of tension and compression forces generated by masticatory muscles. [source] Positional relationships between the masticatory muscles and their innervating nerves with special reference to the lateral pterygoid and the midmedial and discotemporal muscle bundles of temporalisJOURNAL OF ANATOMY, Issue 2 2000KEIICHI AKITA For an accurate assessment of jaw movement, it is crucial to understand the comprehensive formation of the masticatory muscles with special reference to the relationship to the disc of the temporomandibular joint. Detailed dissection was performed on 26 head halves of 14 Japanese cadavers in order to obtain precise anatomical information of the positional relationships between the masticatory muscles and the branches of the mandibular nerve. After complete removal of the bony elements, the midmedial muscle bundle in all specimens and the discotemporal muscle bundle in 6 specimens, derivatives of the temporalis, which insert into the disc were observed. On the anterior area of the articular capsule and the disc of the temporomandibular joint, the upper head of the lateral pterygoid, the midmedial muscle bundle of temporalis and the discotemporal bundle of temporalis were attached mediolaterally, and in 3 specimens the posterosuperior margin of the zygomaticomandibularis was attached to the anterolateral area of the disc. It is suggested that these muscles and muscle bundles contribute to various mandibular movements. Although various patterns of the positional relationships between the muscles and muscle bundles and the their innervating nerves are observed in the present study, relative positional relationships of the muscles and muscle bundles and of nerves of the mandibular nerve are consistent. A possible scheme of the developmental formation of the masticatory muscles based on the findings of the positional relationships between the muscles and the nerves is presented. [source] Neuromuscular function in healthy occlusionJOURNAL OF ORAL REHABILITATION, Issue 9 2010S. E. FORRESTER Summary, This study aimed to measure neuromuscular function for the masticatory muscles under a range of occlusal conditions in healthy, dentate adults. Forty-one subjects conducted maximum voluntary clenches under nine different occlusal loading conditions encompassing bilateral posterior teeth contacts with the mandible in different positions, anterior teeth contacts and unilateral posterior teeth contacts. Surface electromyography was recorded bilaterally from the anterior temporalis, superficial masseter, sternocleidomastoid, anterior digastric and trapezius muscles. Clench condition had a significant effect on muscle function (P = 0·0000) with the maximum function obtained for occlusions with bilateral posterior contacts and the mandible in a stable centric position. The remaining contact points and moving the mandible to a protruded position, whilst keeping posterior contacts, resulted in significantly lower muscle activities. Clench condition also had a significant effect on the per cent overlap, anterior,posterior and torque coefficients (P = 0·0000,0·0024), which describe the degree of symmetry in these muscle activities. Bilateral posterior contact conditions had significantly greater symmetry in muscle activities than anterior contact conditions. Activity in the sternocleidomastoid, anterior digastric and trapezius was consistently low for all clench conditions, i.e. <20% of the maximum voluntary contraction level. In conclusion, during maximum voluntary clenches in a healthy population, maximum masticatory muscle activity requires bilateral posterior contacts and the mandible to be in a stable centric position, whilst with anterior teeth contacts, both the muscle activity and the degree of symmetry in muscle activity are significantly reduced. [source] Influence of neck rotation and neck lateroflexion on mandibular equilibriumJOURNAL OF ORAL REHABILITATION, Issue 5 2010H. J. SCHINDLER Summary, Neuromuscular interaction between neck and jaw muscles has been reported in several studies. However, the influence of experimentally modified posture of the neck on jaw muscle activity during isometric biting was not investigated so far. The aim of the present study was to test by the aid of simultaneous electromyographic and intraoral bite force measurements whether neck rotation and lateroflexion, in contrast to a straightforward neck position, change the isometric cocontraction patterns of masticatory muscles under identical submaximum bite forces of 50,200 N. Electric muscle activity of all masticatory muscles and changes of the reduction point (RP) of the resultant bite force vectors were examined. An anteroposterior displacement of the RPs could be observed for the rotated and lateroflexed neck position in comparison with the straightforward position. On the other hand, the results revealed no significant differences between bilateral muscle activation under the different test conditions. These findings suggest a force transmission between the neck and the masticatory system, but no essential activity changes in the masticatory muscles under short time posture modification of the neck. [source] Ageing and surface EMG activity patterns of masticatory musclesJOURNAL OF ORAL REHABILITATION, Issue 4 2010F. A. CECÍLIO Summary, The purpose of this study was to evaluate the influence of age on the electromyographic activity of masticatory muscles. All volunteers were Brazilian, fully dentate (except for Group I , mixed dentition), Caucasian, aged 7,80, and divided into five groups: I (7,12 years), II (13,20 years), III (21,40 years), IV (41,60 years) and V (61,80 years). Except for Group V, which comprised nine women and eight men, all groups were equally divided with respect to gender (20 M/20 F). Surface electromyographic records of masticatory muscles were obtained at rest and during maximal voluntary contraction, right and left laterality, maximal jaw protrusion and maximal clenching in the intercuspal position. Statistically significant differences (P < 0·05) were found in all clinical conditions among the different age groups. Considerably different patterns of muscle activation were found across ages, with greater electromyographic activity in children and youth, and decreasing from adults to aged people. [source] Relationship between the unilateral TMJ osteoarthritis/osteoarthrosis, mandibular asymmetry and the EMG activity of the masticatory muscles: a retrospective studyJOURNAL OF ORAL REHABILITATION, Issue 2 2010R. MATSUMOTO Summary, The purpose of this retrospective study was to investigate the relationship between the unilateral temporomandibular joint (TMJ) osteoarthritis/osteoarthrosis (OA), mandibular asymmetry and electromyographic (EMG) activity of the masticatory muscles. Twenty-two Japanese women (aged 23·2 ± 5·4 years) and 10 Japanese men (aged 22·4 ± 2·8 years) exhibiting unilateral TMJ OA were included in this study. Two angular and seven linear measurements were obtained for the analysis of the skeletal hard tissues. The cephalometric measurement values (CV) were normalized using the CV ratio for the evaluation of the degree of mandibular asymmetry. The EMG was recorded during maximal voluntary clenching efforts for 10 s in the intercuspal position. The average values of integral EMG (iEMG) of three trials were normalized using the iEMG ratio for the evaluation of the functional balance of the masticatory muscles. The mandibular midline was shifted to the TMJ OA side with a median value of 9·85 mm. The CV ratio of the ramus height of the TMJ OA side was significantly smaller than that of the non-OA side. For the masseter muscle, the iEMG ratio of the TMJ OA side was significantly larger than that of the non-OA side (P < 0·05). These results suggest that unilateral TMJ OA is related to the dentofacial morphology, thus resulting in a mandibular midline shift to the affected side and it is associated with a masticatory muscle imbalance. [source] Small unilateral jaw gap variations: equilibrium changes, co-contractions and joint forcesJOURNAL OF ORAL REHABILITATION, Issue 10 2009H. J. SCHINDLER Summary, After complex prosthetic reconstructions, small differences in vertical distances between the left and right side of the jaw may occur during jaw closing, nevertheless providing bilateral tooth contacts in intercuspation by small deformations of the mandible. Their effects on the co-contraction of the masticatory muscles, the temporomandibular joint reaction forces, and the point of application of the resultant bite force vector in the maxillary occlusion plane , the so-called reduction point , have not been investigated, thus far simultaneously in one sample. The main goal of this study was to investigate variations of these measures in an experimental intercuspation simulated by one anterior and two posterior force transmission points. [source] The effects of manual therapy and exercise directed at the cervical spine on pain and pressure pain sensitivity in patients with myofascial temporomandibular disordersJOURNAL OF ORAL REHABILITATION, Issue 9 2009R. LA TOUCHE Summary, No studies have investigated the effects of the treatments directed at the cervical spine in patients with temporomandibular disorders (TMD). Our aim was to investigate the effects of joint mobilization and exercise directed at the cervical spine on pain intensity and pressure pain sensitivity in the muscles of mastication in patients with TMD. Nineteen patients (14 females), aged 19,57 years, with myofascial TMD were included. All patients received a total of 10 treatment session over a 5-week period (twice per week). Treatment included manual therapy techniques and exercise directed at the cervical spine. Outcome measures included bilateral pressure pain threshold (PPT) levels over the masseter and temporalis muscles, active pain-free mouth opening (mm) and pain (Visual Analogue Scale) and were all assessed pre-intervention, 48 h after the last treatment (post-intervention) and at 12-week follow-up period. Mixed-model anovas were used to examine the effects of the intervention on each outcome measure. Within-group effect sizes were calculated in order to assess clinical effect. The 2 × 3 mixed model anova revealed significant effect for time (F = 77·8; P < 0·001) but not for side (F = 0·2; P = 0·7) for changes in PPT over the masseter muscle and over the temporalis muscle (time: F = 66·8; P < 0·001; side: F = 0·07; P = 0·8). Post hoc revealed significant differences between pre-intervention and both post-intervention and follow-up periods (P < 0·001) but not between post-intervention and follow-up period (P = 0·9) for both muscles. Within-group effect sizes were large (d > 1·0) for both follow-up periods in both muscles. The anova found a significant effect for time (F = 78·6; P < 0·001) for changes in pain intensity and active pain-free mouth opening (F = 17·1; P < 0·001). Significant differences were found between pre-intervention and both post-intervention and follow-up periods (P < 0·001) but not between the post-intervention and follow-up period (P > 0·7). Within-group effect sizes were large (d > 0·8) for both post-intervention and follow-up periods. The application of treatment directed at the cervical spine may be beneficial in decreasing pain intensity, increasing PPTs over the masticatory muscles and an increasing pain-free mouth opening in patients with myofascial TMD. [source] Influence of playing wind instruments on activity of masticatory musclesJOURNAL OF ORAL REHABILITATION, Issue 9 2007A. GOTOUDA Summary, The aim of this study was to elucidate the influence of change in sound tone of playing wind instruments on activity of jaw-closing muscles and the effect of sustained playing for a long time on fatigue of jaw-closing muscles. Electromyograms (EMG) of 19 brass instrument players and 14 woodwind instrument players were measured while playing instruments in tuning tone and high tone and under other conditions. Nine brass instrument players and nine woodwind instrument players played instruments for 90 min. Before and after the exercise, power spectral analyses of EMG from masseter muscles at 50% of maximum voluntary clenching level were performed and mean power frequency (MPF) were calculated. Root mean square (RMS) of EMG in masseter and temporal muscles while playing were slightly larger than those at rest but extremely small in comparison with those during maximum clenching. Root mean square in orbicularis oris and digastric muscles were relatively large when playing instruments. In the brass instrument group, RMS in high tone was significantly higher than that in tuning tone in all muscles examined. In the woodwind instrument group, RMS in high tone was not significantly higher than that in tuning tone in those muscles. Mean power frequency was not decreased after sustained playing in both instrument groups. These findings indicate that contractive load to jaw-closing muscles when playing a wind instrument in both medium and high tone is very small and playing an instrument for a long time does not obviously induce fatigue of jaw-closing muscles. [source] Relation between cervical posture on lateral skull radiographs and electromyographic activity of masticatory muscles in caucasian adult women: a cross-sectional studyJOURNAL OF ORAL REHABILITATION, Issue 9 2007S. TECCO Summary, The aim of this study was to evaluate the association between cervical posture on lateral skull radiographs and surface electromyographic recordings (sEMG) of head and neck muscles. The sample comprised 40 Caucasian adult females, average age 26·8 (20,48); lateral skull radiographs were obtained in natural head position (mirror position). sEMG activity was bilaterally investigated for the following muscles: masseter, anterior temporalis, digastric, posterior cervical, sternocleidomastoid and upper and lower trapezius. All muscles were monitored at rest and during maximal voluntary clenching (MVC). A Pearson's correlation coefficient revealed significant correlations (P < 0·01) between cranio-cervical angulations and sEMG activity of masseter, digastric, lower trapezius, during MVC and anterior temporalis at rest. Significant correlations (P < 0·01) were also found between cervical lordosis angle and sEMG activity of masseter (during MVC) and lower trapezius (at rest). In view of transversal method, no conclusion was possible about the mechanism concerning these results. Future longitudinal studies should be directed to understand the extent of environmental and genotype influences by masticatory muscle activity on cervical posture. [source] Electromyographic activity of masticatory, neck and trunk muscles of subjects with different skeletal facial morphology , a cross-sectional evaluationJOURNAL OF ORAL REHABILITATION, Issue 7 2007S. TECCO summary, The electromyographic pattern activity of masticatory, neck and trunk muscles was assessed using surface electromyography (sEMG) in 60 Caucasian adult females (20 subjects in skeletal class I, 20 subjects in skeletal class II and 20 subjects in skeletal class III), classified on the base of their skeletal class (ANB angle), corrected on the base of maxillary and mandibular rotations. The sEMG activity was recorded at mandibular rest position and during maximal voluntary clenching. At mandibular rest position, the sEMG activities of masseter and anterior temporal muscles were significantly higher in class III subjects than in class I and class II subjects, that showed no significant difference between them. Then, the sEMG activities of posterior cervicals and upper trapezius were significantly higher in skeletal class III subjects than in the other two groups. During maximal voluntary clenching, no significant difference was observed in the sEMG activity of masticatory muscles among the three considered groups. However, the sEMG activities of posterior cervicals and upper trapezius were significantly higher in skeletal class III subjects than in the other two groups, which showed no significant difference between them. In conclusion, the skeletal class seems to affect the sEMG pattern activity of masticatory, neck and trunk muscles. [source] Preliminary rapport on head posture and muscle activity in subjects with class I and IIJOURNAL OF ORAL REHABILITATION, Issue 11 2005I. C. GADOTTI summary, Forward head posture may cause alterations in the stomatognathic system, including changes in the muscle activity of the masticatory muscles and dental occlusion alterations. Considering the need for further understanding of the relationship between the stomatognathic system and the cervical region, the purpose of this study was to analyse the head posture and the electromyographic (EMG) activity of the anterior portion of temporal and masseter muscles bilaterally among bruxist's subjects with different dental occlusion classifications using the Angle method. The study consisted of 20 female volunteers, between the ages of 17 and 27 years. They were separated into two groups (class I and class II occlusions) according to a dentist-performed evaluation. An assessment of forward head posture was conducted using a photographic technique (angular calculus) combined with a clinical analysis. In the EMG analyses, active differential surface electrodes (Ag) were utilized and were placed bilaterally on the belly of masseter and temporal muscles, perpendicular to the muscles fibres. The EMG signal recorded during bilateral isotonic mastication, was presented using the Root Mean Square and was processed by Matlab software. The results indicated that the EMG responses of temporal and masseter muscles tend to be modified by occlusion alteration class II. Subjects with class II occlusion tended to present more occurrence of forward head posture with alterations in the muscle activity pattern between masseter and temporal muscles. [source] Effects of a functional appliance on masticatory muscles of young adults suffering from muscle-related temporomandibular disordersJOURNAL OF ORAL REHABILITATION, Issue 6 2004T. Castroflorio summary, The aim of this study was to investigate the effects of an original orthodontic functional appliance [function generating bite for deep bite correction (FGB-D)] on masticatory muscle activity in subjects suffering from muscle-related temporomandibular disorders (TMD). Electromyographic (EMG) analysis was performed on 33 young adults (nine men, 24 women) to evaluate the contractile symmetry of the right and left masseter and anterior temporalis muscles. The subjects were divided into three groups: a muscle-related TMD group requiring orthodontic treatment for deep bite correction (three men, eight women) and treated with FGB-D; a muscle-related TMD group not requiring orthodontic treatment (three men, eight women) and treated with a Michigan occlusal splint; and a TMD-free group (three men, eight women) as a control group. Records were made by surface EMG of maximum voluntary teeth clenching, with and without the functional appliance or occlusal splint in place, before and after 12 months of therapy. A torque index was derived from the surface EMG recordings to estimate lateral displacement of the mandible. The results show that the FGB-D corrects the torque index and thus the lateral displacement of the mandible. [source] The prevalence and treatment needs of symptoms and signs of temporomandibular disorders among young adult malesJOURNAL OF ORAL REHABILITATION, Issue 9 2003N. J. Nassif Summary, A temporomandibular disorder (TMD) screening history and screening examination was performed on 523 young adult males. The screening forms were similar to those TMD forms developed and formulated under the auspices of the American College of Prosthodontists. In turn, the substance of the latter forms was initially derived from the recommendations of the President's TMD Conference of the American Dental Association, with 62 eminent researchers, educators and clinicians as participants. Each subject was given a TMD self-administered screening history form to complete, formatted in a check , the block format. It included all items considered to be classic TMD symptoms. The screening examination was performed extraorally and included (i) range of jaw movement, (ii) digital palpation of selected masticatory muscles and palpation over the pre-auricular temporomandibula joint (TMJ) area and (iii) digital palpation for TMJ sounds during jaw movement. The subjects were categorized into the following four categories: 0 = no symptoms/signs, 1 = insignificant moderate symptoms and/or signs, 2 = significant moderate symptoms and/or signs, and 3 = severe symptoms and/or signs. The overall results showed that 75% of the subjects had TMD symptoms and/or signs. There were 6·9% in category 1, 51·4% in category 2, and 16·7% in category 3. It was recommended that subjects in category 2 and 3 should have a comprehensive TMD evaluation, in order to further identify the recommended need for TMD Therapy. [source] Effects of interocclusal appliances on EMG activity during parafunctional tooth contactJOURNAL OF ORAL REHABILITATION, Issue 6 2003A. L. Roark summary, To test the hypothesis that a flat plane interocclusal appliance affects the electromyographic (EMG) activity of the temporalis and masseter muscles in pain-free individuals, maxillary splints were fabricated for 20 individuals who reported no history, signs or symptoms of myofascial pain or arthralgia as determined by two trained, independent examiners. Subjects were instructed to establish light tooth contact, maximum clenching, and moderate clenching with/without the splint in place (as determined by random assignment) while EMG data from the left and right temporalis and masseter muscles were recorded. A 5-min biofeedback training session to relax the masticatory muscles was followed by a repetition of the tooth contact/clenching tasks with/without the splint in place. With the splint in place, the activity of the temporalis muscles decreased for all tasks, significantly for the left and right temporalis under maximal clenching and for the right temporalis under moderate clenching. In contrast, the activity of the masseter muscles increased under light and moderate clenching (significantly for the left masseter under moderate clenching) and decreased slightly under maximal clenching. The effectiveness of interocclusal appliances may be due to mechanisms other than redistribution of adverse loading. [source] Task-related electromyographic spectral changes in the human jaw musclesJOURNAL OF ORAL REHABILITATION, Issue 9 2002M. FARELLA The masticatory muscles differ in their fibre type composition. It can therefore be expected that their electromyographic (EMG) power spectra will differ during the performance of different bite force tasks. In the present study surface EMG activity was picked up from the masseter, and anterior and posterior temporalis muscles of nine adult subjects. Direction and magnitude of bite force were recorded using a three-component force transducer. Bite forces were exerted in five different directions: vertical, forward, backward, to the right and to the left of the subject. Non-vertical forces were kept at an angle of 15° from the vertical. Force levels of 25, 50, 100 and 200 N were exerted in each of the investigated directions. Data collected were analysed by means of a regression model for repeated measurements. It appeared that the mean power frequency (MPF) values of the posterior temporalis were significantly lower (P < 0·01) than those of the masseter and anterior temporalis. The MPF values of the masseter muscles decreased with an increase of bite force magnitude (P < 0·001) whereas the MPF values of the anterior and posterior temporalis did not change significantly (P > 0·05). The MPF values were significantly influenced by the direction of bite force (P < 0·01). The observed changes of MPF are possibly related to the recruitment of different fibre types and support the concept that the masticatory muscles behave heterogeneously. [source] Genioglossus muscle activity during rhythmic open,close jaw movementsJOURNAL OF ORAL REHABILITATION, Issue 8 2000S. Hiyama The purpose of this study was to examine genioglossus muscle activity during rhythmic open,close jaw movements. The electromyographic activity of the genioglossus muscle was recorded with a bipolar fine-wire electrode in six healthy males. The electromyographic activities of the ipsilateral masseter and digastric muscles were simultaneously recorded with bipolar surface electrodes. The subjects were instructed to perform rhythmic open,close jaw movements in time with a metronome set at 23, 27, 33, 42 and 50 beats/min. In all of the subjects, rhythmic electromyographic activity of the genioglossus muscle was recorded in both the jaw-opening and jaw-closing phases. The activity of the genioglossus muscle was predominantly recorded in the jaw-opening phase in two subjects, and in the jaw-closing phase in two subjects. The burst duration of the electromyographic activity of the genioglossus muscle changed linearly in accordance with the cycle duration. However, the latency from the onset of the electromyographic activity of the masseter or digastric muscle to that of the genioglossus muscle was almost constant, independent of the cycle duration. Based on these findings, we conclude that the activity of the human genioglossus muscle is closely linked to that of masticatory muscles under the control of a closely related central pattern generator. [source] INFLUENCE OF MEASUREMENT TECHNIQUE, TEST FOOD, TEETH AND MUSCLE FORCE INTERACTIONS IN MASTICATORY PERFORMANCEJOURNAL OF TEXTURE STUDIES, Issue 1 2007FLÁVIA RIQUETO GAMBARELI ABSTRACT The role of texture and flavors in mastication is evident, but it is difficult to understand the interactions among food properties, oral physiology and perception. Mastication results from rhythmic mandibular movements. The teeth and masticatory muscles together form the mechanism whereby the food particles are fragmented. Masticatory performance and efficiency are defined as the capacity to reduce natural or artificial test materials during mastication, or by counting the number of strokes required to reduce food, respectively. Foods eaten for nourishment are very different from the industrial test materials used to quantify masticatory performance, thus, divergences could arise if the chewable material can or cannot be swallowed. This study presents a synopsis of masticatory performance methods, which is also related to muscle force, number of teeth and test chewing substance diversity. PRACTICAL APPLICATIONS The attributes of food, such as appearance, flavor and texture, as well as its interaction with saliva, number of teeth and conditions of the biomechanical system, influence the chewing process. In addition, reflex control and cognition can influence food perception and breakdown in the mouth. Food acceptability and choice depend on sensory properties of the food, which are perceived during chewing and swallowing. Masticatory performance and maximal occlusal force measurement may provide essential information that could lead to an appropriate diagnosis as regards masticatory function. Masticatory efficiency and performance can be measured to determine the individual's capacity to comminute a natural or a chewable test material. A material with uniform properties that can be reliably reproduced is essential to provide an ideal test bolus for the scientific study of masticatory effectiveness. [source] Alteration of central motor excitability in a patient with hemimasticatory spasm after treatment with botulinum toxin injectionsMOVEMENT DISORDERS, Issue 1 2006Pablo Mir MD Abstract Hemimasticatory spasm (HMS) is a condition characterized by paroxysmal involuntary contraction of masticatory muscles. We performed an electrophysiological investigation of a single patient with HMS to identify any pathophysiological changes associated with the condition. We identified a delayed M wave and jaw jerk on the affected side and an absent masseteric silent period during spasm. Botulinum toxin injections successfully treated the clinical symptoms and resulted in a significant reduction in the excitability of the blink reflex recovery cycle. These data suggest that HMS may be due to ectopic activity in the motor portion of the trigeminal nerve that is capable of inducing changes in the excitability of central reflex pathways. These changes can be altered by successful treatment with botulinum toxin. © 2005 Movement Disorder Society [source] Denervation hypertrophy may mimic local tumor spread on magnetic resonance imagingMUSCLE AND NERVE, Issue 1 2006Carsten Wessig MD Abstract We report a patient with an extensive paranasal sinus carcinoma. One year after tumor resection, magnetic resonance imaging (MRI) showed swelling of the ipsilateral masticatory muscles with signal increase on T2-weighted images and gadolinium-DTPA uptake, suggestive of local tumor infiltration. However, electromyography, biopsy, and follow-up MRI confirmed denervation pseudohypertrophy of the muscles innervated by the mandibular nerve and excluded tumor recurrence. Muscle denervation and pseudohypertrophy should be considered in the differential diagnosis of appropriate patients with suspected tumor recurrence. Muscle Nerve, 2006 [source] Masseter muscle thickness as a predictive variable in treatment outcome of the twin-block appliance and masseteric thickness changes during treatmentORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 4 2010S Kiliaridis To cite this article: Kiliaridis S, Mills CM, Antonarakis GS: Masseter muscle thickness as a predictive variable in treatment outcome of the twin-block appliance and masseteric thickness changes during treatment Orthod Craniofac Res 2010;13:203,213 Structured Abstract Authors,,, Kiliaridis S, Mills CM, Antonarakis GS Objectives,,, To estimate the association of initial masseter muscle thickness with treatment outcomes using functional appliances and the effect of treatment on masseter muscle thickness. Material and Methods,,, Twenty-two children, aged 8,12, with skeletal and dental class II relationships and increased overjet were treated with twin-block appliances for 9,17 months, until a class I molar relationship and decreased overjet was achieved. Dental casts, lateral cephalograms, and ultrasonographic measurements of the masseter muscle were performed before and after treatment. Twenty-two children, aged 8,12, without immediate need for orthodontic treatment, served as controls. They were observed for 11,17 months, and ultrasonographic masseter muscle measurements were taken before and after the observation period. Results,,, Masseter muscles in treated children were thinner at the end of treatment, while untreated controls showed an increase in thickness. Treated children with thinner pre-treatment muscles showed greater mandibular incisor proclination, distalisation of maxillary molars, and posterior displacement of the cephalometric A point during treatment. Conclusion,,, Treatment of a dental class II relationship with functional appliances leads to mild atrophy of the masticatory muscles, possibly because of their decreased functional activity. The initial condition of the muscles may be associated with mandibular incisor proclination, and the position of maxillary first molars and A point. [source] Comparative Functional Morphology of the Masticatory Apparatus in the Long-snouted CrocodilesANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 4 2002H. Endo Summary The masticatory muscles and their related structures of the skull were observed in the Indian gavial (Gavialis gangeticus), the false gavial (Tomistoma schlegelii), and the African slender-snouted crocodile (Mecistops cataphractus) to detail some morphological differences in comparison with the other crocodile species, and to compare and elucidate the functional strategy of themasticatory apparatus in these long-snouted species. The Musculus pterygoideus posterior was relatively smaller in the three species compared with many short-snouted crocodiles. It suggests that the masticatory power in fish-eating long-snouted species is not so high as in the short-snouted crocodiles, while the masticatory muscles were morphologically different among the three long-snouted species as follows. The M. pterygoideus posterior of the false gavial was extended in the lateral side of the lower jaw unlike the Indian gavial. The M. pseudotemporalis and the Fenestra supratemporalis were largely developed in the Indian gavial, however we suggest that the other two species possess the weak bundles in this muscle. The false gavial and the African slender-snouted crocodile have the pterygoid bone well-developed extending dorso-ventrally and it is suggested that the M. adductor mandibulae posterior attached to the pterygoid bone may be much larger than the Indian gavial. These data morphologically clarify the masticatory mechanism in the long-snouted crocodiles different from the short-snouted species, and demonstrate that the evolutional strategy to share the functional role in the masticatory muscles have been differently established between the Indian gavial and the other two species. We also obtained the morphological data in the fossil skull of the Machikane crocodile (Toyotamaphymeia machikanense) and concluded from the fossil characters that the considerable developments of the M.pterygoideus posterior and the M.pseudotemporalis in this species had not morphologically been consistent with both the Indian and false gavials. [source] An anatomical study of the muscles that attach to the articular disc of the temporomandibular jointCLINICAL ANATOMY, Issue 8 2009Kosuke Matsunaga Abstract The masticatory muscles are generally described as the muscles that originate from the cranium and insert on the mandible. Some of the masticatory muscles also insert into the articular disc of the temporomandibular joint. Although there are numerous reports of studies on the attachment of the fibers to the disc, most reports discuss only one muscle. We have shown that the masticatory muscles are not simply a group of clearly independent muscles, but that these muscles contain various transitional muscle bundles among the major muscles. From this point of view, we carried out minute dissection of the collective muscles and muscle bundles surrounding the temporomandibular joint. We dissected 40 head halves of 20 Japanese cadavers (10 males, 10 females: average 79.6 yr). After complete removal of the bony elements, the structures surrounding the temporomandibular joint were investigated en-block. In all specimens, the superior surface of the upper head of lateral pterygoid and the midmedial muscle bundle were attached to the disc. In some specimens, the discotemporal bundle, zygomaticomandibularis, and masseter were attached to the anterior surface of the disc. The total vector of these muscles pulls the disc anteriorly. In contrast, the vector of the muscles to the condylar processes of the mandible pulls the mandible medially. From these observations, it seems that the fibers, which attach to the disc act to steady the disc against the masticatory movement. Clin. Anat. 22:932,940, 2009. © 2009 Wiley-Liss, Inc. [source] Neuromuscular coordination of masticatory muscles in subjects with two types of implant-supported prosthesesCLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2004Virgilio F. Ferrario Abstract Objectives: To compare the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant-supported prostheses and implant overdentures. Material and methods: Nineteen subjects aged 45,79 years were examined. Fourteen were edentulous and had been successfully rehabilitated with (a) maxillary and mandibular implant-supported fixed prostheses (seven patients); (b) mandibular implant overdentures and maxillary complete dentures (seven patients). Five control subjects had natural dentition or single/partial (no more than two teeth) tooth or implant fixed dentures. Surface EMG of the masseter and temporal muscles was performed during unilateral gum chewing and during maximum teeth clenching. To reduce biological and instrumental noise, all values were standardized as percentage of a maximum clenching on cotton rolls. Results: During clenching, temporal muscle symmetry was larger in control subjects and fixed implant-supported prosthesis patients than in overdenture patients (analysis of variance, P=0.005). No differences were found in masseter muscle symmetry or in muscular torque. Muscle activities (integrated areas of the EMG potentials over time) were significantly larger in control subjects than in implant-supported prosthesis patients (P=0.014). In both patient groups, a poor neuromuscular coordination during chewing, with altered muscular patterns, and a smaller left,right symmetry than in control subjects were found (P=0.05). No differences in masticatory frequency were found. Conclusion: Surface EMG analysis of clenching and chewing showed that fixed implant-supported prostheses and implant overdentures were functionally equivalent. Neuromuscular coordination during chewing was inferior to that found in subjects with natural dentition. Résumé Le but de cette étude a été de comparer les caractéristiques éléctromiographiques (EMG) de muscles masticateurs chez des patients avec des prothèses fixées sur implant et des prothèses amovibles sur implants. Dix-neuf patients de 45 à 79 ans ont été examinés. Quatorze étaient édentés et ont été traités avec succès par a) une prothèse fixée sur des implants au niveau maxillaire et mandibulaire (sept patients), b) des prothèses amovibles ancrées sur implant au niveau de la mandibule et des prothèses amovibles totales supérieures (sept patients). Les cinq contrôles avaient soit une dentition naturelle soit des couronnes sur implants ou dent unique. L'EMG de surface des muscles masséter et temporaux a été effectué durant la mastication unilatérale de gomme à mâcher et à la force maximale de fermeture. Pour diminuer le bruit biologique et instrumental, toutes les valeurs ont été standardisées en pourcentage d'une force maximale de fermeture sur des rouleaux de coton. Durant la fermeture, la symétrie musculaire temporale était plus importante chez les sujets contrôles et les prothèses fixées sur implants que chez les patients avec prothèse amovible (analyse de variance, p=0,005). Aucune différence n'a été constatée dans la symétrie musculaire du masséter ou dans la torsion musculaire. Les activités musculaires (zones intégrées des potentiels EMG avec le temps) étaient significativement plus importantes chez les contrôles que chez les patients avec prothèses fixées sur implants (p=0,014). Dans les deux groupes de patients, une pauvre coordination neuromusculaire durant le mâchonnement, avec des modèles musculaires altérés, et une plus petite symétrie gauche-droite étaient constatées chez les sujets contrôles (p=0,05). Aucune différence dans la fréquence masticatoire n'a été trouvée. L'analyse EMG de surface de fermeture et de mastication montraient que les prothèses fixées sur implant et les prothèses amovibles sur implants étaient fonctionnellement équivalentes. Cependant la coordination neuromusculaire durant la mastication était inférieure à celle trouvée chez les sujets avec dentition naturelle. Zusammenfassung Ziel: Die EMG-Charakteristiken der Kaumuskeln in Patienten mit festsitzenden implantatgetragenen Prothesen und implantatgetragenen Hybridprothesen zu vergleichen. Material und Methode: Neunzehn Patienten im Alter von 45 bis 79 Jahren wurden untersucht. Vierzehn davon waren zahnlos und erfolgreich wiederhergestellt worden mit a) festsitzenden implantatgetragenen Ober- und Unterkieferprothesen (sieben Patienten); b) Unterkieferhybridprothesen und OK-Totalprothesen (sieben Patienten). Die fünf Kontrollpatienten hatten eine natürliche Bezahnung oder Einzelkronen bzw. kleine Brücken (nicht mehr als zwei Zähne) auf Implantaten oder Zähnen. Während einseitigem Kaugummikauen und maximalem Zähnepressen wurden Messungen der Oberflächen-EMGs der Masseter- und Temporalmuskulatur durchgeführt. Um das biologische und instrumentelle Rauschen zu unterdrücken, wurden alle Werte als Prozentanteil des maximalen Pressens auf Watterollen standardisiert. Resultate: Während des Pressens war die temporale Muskelsymmetrie bei den Kontrollpatienten und den Patienten mit festsitzenden implantatgetragenen Prothesen grösser als bei den Probanden mit Hybridprothesen (Varianzanalyse, p=0.005). Bei der Symmetrie der Massetermuskeln und im muskulären Drehmoment konnten keine Unterschiede gefunden werden. Die Muskelaktivitäten (integrierte Areale der EMG-Potentiale über die Zeit) waren bei den Kontrollpatienten signifikant tiefer als bei den Probanden mit implantatgetragenen Prothesen (p=0.014). Bei beiden Patientengruppen konnte eine schlechtere neuromuskuläre Koordination während des Kauens mit veränderlichen muskulären Mustern und einer geringeren links-rechts Symmetrie als bei den Kontrollpatienten gefunden werden (p=0.05). Bei der Kaufrequenz bestanden keine Unterscheide. Schlussfolgerung: Die Analyse der Oberflächen-EMG beim Pressen und Kauen zeigte, dass festsitzende implantatgetragene Prothesen und implantatgetragene Hybridprothesen funktionell gleichwertig sind. Die neromuskuläre Koordination während des Kauens war schlechter als bei Probanden mit natürlicher Bezahnung. Resumen Objetivos: Comparar las características del EMG de los músculos masticatorios en pacientes con prótesis fija implanto-soportada y sobredentaduras en implantes. Material y métodos: Se examinaron 19 sujetos de edades entre 45 y 79 años. Catorce eran edéntulos, y habían sido rehabilitados con éxito con a) prótesis fija implanto-soportada maxilar y mandibular (siete pacientes); b) sobredentadura completa en implantes maxilar y mandibular (siete pacientes). Cinco pacientes de control tenían dentición natural o dentaduras fijas sobre implantes o dientes unitarias o parciales (no mas de 2 dientes). Se llevó a cabo EMG de superficie de los músculos maseteros y temporales durante mascado de chicles unilateralmente, y durante cierre máximo. Para reducir las interferencias biológicas e instrumentales, todos los valores se estandarizaron como porcentajes de un cierre máximo sobre rollos de algodón. Resultados: Durante el cierre, la simetría de los músculos temporales fue mayor en los sujetos de control y en los pacientes de prótesis fijas implanto-soportadas que en los pacientes con sobredentaduras (análisis de varianza, p=0.005). No se encontraron diferencias en la simetría del músculo masetero o en el torque muscular. Las actividades musculares (áreas integradas de los potenciales del EMG a lo largo del tiempo) fueron significativamente mayores en los sujetos de control que en los pacientes con prótesis implantosoportada (p=0.014). En ambos grupos de pacientes, se encontró una coordinación neuromuscular mas pobre durante el mascado, con patrones musculares alterados, y una menor simetría derecha-izquierda que en los sujetos de control (p=0.05). No se encontraron diferencias en la frecuencia masticatoria. Conclusión: El análisis del EMG de superficie de máxima mordida y de mascado mostró que las prótesis fijas implanto-soportadas y las sobredentaduras en implantes fueron funcionalmente equivalentes. La coordinación neuromuscular durante el mascado fue inferior a aquella encontrada en sujetos con dentición natural. [source] | |||||||||||||