Dissertations / Theses on the topic 'Jaw muscle pain'

Background and Aims: Temporomandibular disorders are clinical conditions that often involve pain in the masticatory muscles, the temporomandibular jaw joint and/or associated structures. The association between muscle pain and muscle activity is often explained by uniform increases or decreases in motor unit activity throughout a muscle but recent evidence suggests more complex changes within a painful muscle. The general aim of this study was to determine if experimentally induced masseter muscle pain modifies temporalis muscle activity. Methods: 20 healthy participants received experimental pain through hypertonic saline (5% NaCl) infusion into the right masseter; pain intensity was maintained at 40-60/100 mm on a visual analogue scale (VAS). Standardized biting tasks were performed with an intraoral force transducer while single motor unit (SMU) activity was recorded from 2 intramuscular electrodes (right masseter and right temporalis). The tasks were repeated in 4 blocks: baseline 1, hypertonic saline infusion, isotonic saline infusion, baseline 2. Each block had 3 isometric biting tasks: a slow and a fast ramp jaw closing task and a 2 step-levels jaw closing task (2 force levels: step 1 and step 2). Results: 83 SMUs were discriminated from the temporalis and 58 from the masseter muscle. This study demonstrated that induced muscle pain in the right masseter can be associated with the activation of new SMUs and the silencing of other single motor units in the painful masseter muscle as well as in the right temporalis muscle, which did not receive noxious stimulation with the hypertonic saline. No differences between pain and no pain trials were found in thresholds and firing rates of SMUs from the temporalis muscle. Discussion and conclusion: The present findings are consistent with previous findings from the limb (Hodges and Tucker 2011; Tucker et al. 2009) and rather than supporting uniform increases or decreases in motor unit activity throughout a muscle, suggest that there is a reorganization of motor unit activity across the entire jaw motor system in experimental pain.

Chronic jaw muscle pain is the most commonly diagnosed condition in temporomandibular disorders with 10.1% of the Australian population displaying symptoms. The present study proposed to investigate the effect of biological and behavioural responses to different stressors on the function of jaw muscles of participants with chronic jaw muscle pain through two experiments. In the first experiment, two chronic pain groups and a pain free group identified stressful daily events (daily hassles) for frequency and severity. Significant difference between the groups was shown for severity but not frequency with highest scores relating to health daily hassles. The second study assessed the effect of two stressors on jaw movement and muscle activity in chronic jaw muscle pain participants compared to controls. All participants undertook open/close jaw movements, free gum and standardised gum chewing movements. No significant difference between the groups was reported for movement amplitude and velocity of the jaw movements after the stressors. Of the five jaw muscles recorded during movement only one was significantly different between the groups after the stressors. Grouped data from all participants showed a significant effect of stressor for most of the jaw movement parameters and for jaw muscle activity across various muscles and stressors. Differences in the current study compared to previous studies may be that the chronic jaw muscle pain group were not dissimilar to the control group although clinically diagnosed as TMD and reporting jaw muscle pain throughout the experiment. The results do not support the current jaw muscle pain or stress models although the data are consistent with pain leading to a redistribution of motor unit activation within and between muscles. The results of the current study have identified inconsistencies with previous studies and highlighted the complex interrelationship between pain and stress that need further exploration.

Objectives: To assess the expression of the symptoms of jaw muscle pain and its association with alterations in biochemistry, other symptoms and the carriage of staphylococci. Methods: Three different study populations were assessed. The first was selected and examined by the author and consisted of 43 pain and 41 age and sex matched controls. The second was a study of CFS patients who were blinded to the author and the author subsequently examined the associations between jaw muscle symptom reporting and the standardised biochemistry measures. The third study was also blinded to the author but included an investigation of staphylococci and certain cytokine and biochemistry measures. Results: The three studies clearly establish an association between the carriage of toxicogenic coagulase negative staphylococci and the expression of jaw muscle pain in both males and females. These associations were homogeneous and were found whether the patients were selected on the basis of having jaw muscle pain or selected from within a population of patients selected on the basis of having Chronic Fatigue Syndrome. The studies associated the changes with variations in biochemistry and these were in turn associated with symptom expression within the jaw muscle pain patients. These biochemical alterations included the dysregulation of immune cell counts, cytokines, electrolyte and protein metabolism. These symptoms and biochemical changes were associated with pain severity and illness duration and staphylococcal toxin production. From the data a model was developed which shows the mechanisms involved in the development of chronic pain in the jaw muscles. Conclusions: The carriage of toxicogenic coagulase-negative staphylococci were found to be associated with the expression of jaw muscle pain and the alterations in biochemistry associated with these symptoms.

Doctor of Philosophy
This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

Doctor of Philosophy
This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

Objectives: To assess the expression of the symptoms of jaw muscle pain and its association with alterations in biochemistry, other symptoms and the carriage of staphylococci. Methods: Three different study populations were assessed. The first was selected and examined by the author and consisted of 43 pain and 41 age and sex matched controls. The second was a study of CFS patients who were blinded to the author and the author subsequently examined the associations between jaw muscle symptom reporting and the standardised biochemistry measures. The third study was also blinded to the author but included an investigation of staphylococci and certain cytokine and biochemistry measures. Results: The three studies clearly establish an association between the carriage of toxicogenic coagulase negative staphylococci and the expression of jaw muscle pain in both males and females. These associations were homogeneous and were found whether the patients were selected on the basis of having jaw muscle pain or selected from within a population of patients selected on the basis of having Chronic Fatigue Syndrome. The studies associated the changes with variations in biochemistry and these were in turn associated with symptom expression within the jaw muscle pain patients. These biochemical alterations included the dysregulation of immune cell counts, cytokines, electrolyte and protein metabolism. These symptoms and biochemical changes were associated with pain severity and illness duration and staphylococcal toxin production. From the data a model was developed which shows the mechanisms involved in the development of chronic pain in the jaw muscles. Conclusions: The carriage of toxicogenic coagulase-negative staphylococci were found to be associated with the expression of jaw muscle pain and the alterations in biochemistry associated with these symptoms.

Objectives: Previous studies in the Oral Neurophysiology Laboratories in Dundee have defined the electromyographic properties of the inhibitory jaw reflex that can be evoked in human subjects by electrical stimulation of the lip. This reflex, in contrast with the more widely studied biphasic inhibitory reflexes evoked by stimulation of intra-oral nerves, consists of just a single phase of inhibition and usually requires the application of stimuli which excite nociceptive nerves. The aims of the present studies were to define the mechanical manifestations of this reflex in the form of changes in biting forces, and to investigate whether the mechanical manifestation of the inhibitory jaw reflex evoked by stimulation of the human upper lip, can be modulated by experimentally-controlled conditions that mimic symptoms of a myogenous temporomandibular disorder. Methods: Three series of experiments were performed on 49 volunteer subjects in total. The experiments involved recording bite forces between the anterior teeth and electromyograms (EMGs) from the masseter muscles. Transcutaneous electrical stimuli were applied to the hairy skin of upper lip while the subjects maintained a biting force of around 50N with the aid of visual feedback. In the first series of experiments, a range of electrical stimuli below and above the nociceptive threshold was delivered. In the second set of experiments, double stimuli with a range of different inter-stimulus intervals were applied. Finally in a third series of experiments, electrical stimulation was repeated before, immediately after, and 5 and 10 minutes following a 3-minute accelerated chewing task. This task consisted of chewing 1.5g of a tough chewing gum at 1.5 times the subject’s natural chewing rate and in 18 cases, muscle fatigue and/or pain were reported by the subjects. Results: Following stimulation at intensities that were described as sharp or painful, all the subjects showed both a suppression of the masseter EMG and a reduction of biting force. When analysing the maximum responses in each subject, the mean reduction in the EMG inhibition was to 15.78 ± 14.4% and 10.39 ± 7.92% of the baseline (for the ipsi- and contra-lateral EMGs respectively), whereas the biting force was reduced only to 83.98 ± 11.04% of baseline (+ S.D.). The latencies of onset of these responses were: 38.17 ± 3.58ms, 38.97 ± 4.49ms and 51.83 ± 6.23ms respectively. The response observed in the force record was weaker than in that observed in either EMG (Paired t tests, P < 0.005 in both cases). When applying double stimuli, it was found that the prolongation of the EMG inhibitory jaw reflex (to 144.70 ± 46.93% of the control level) evoked by double stimulation of the upper lip (with a 10 ms inter-stimulus interval) resulted in a greater increase in the depth of the accompanied relaxation (to 223.63 ± 70.88% of that seen in the control responses) compared to a relatively smaller increase in the duration of the relaxation (to 128.32 ± 27.23% of that seen in the control responses). Following the accelerated chewing task, 17 out of 22 subjects reported pain and/or fatigue in one or both of the masseter muscles. The integral for the bite force relaxation significantly decreased in size immediately following the conditioning procedure (to 76.04 ± 35.63% of the control level, P = 0.014; single sample t-test with Bonferroni correction, test value 100). Conclusion: The inhibitory jaw reflex evoked by stimulation of the human lip can be demonstrated mechanically as well as electromyographically although the mechanical version of the response appears less marked. In addition to that, the onset of reflex relaxation in bite force lags several milliseconds behind the corresponding reductions in electromyographic activity. The depth of force relaxation can be increased by increasing the duration of EMG recorded inhibitory reflex. Finally, the results from a chewing task suggest that induced acute pain and/or fatigue cause clear changes in the mechanical manifestation of this inhibitory jaw reflex.

Background and aims: The Pain Adaptation Model and the Vicious Cycle Theory are older theories of the effects of pain on motor activity. While some data sets are consistent with these theories, other data sets are not, and a number of new models (the Integrated Pain Adaptation Model; Theory of Motor Adaptation to Pain) have been proposed. Two of these models propose a reorganization of motor activity in pain. The aim of the present study was to determine whether experimental masseter muscle pain resulted in a change in muscle activity at two different sites within the masseter muscle during the performance of isometric jaw-closing tasks in asymptomatic participants. Methods: Single motor unit (SMU) activity was recorded with bipolar fine wire electrodes at 2 sites within the right masseter muscle during the performance of standardized isometric biting on an intraoral force transducer in 17 healthy participants. Participants performed standardized biting trials during infusion of 5% hypertonic saline into the right masseter (pain), and during isotonic saline infusion (control). Recruitment patterns, force thresholds and firing rates were compared between pain and control trials. Results: A total of 50 SMUs were discriminated from the 2 sites. Changes in recruitment patterns of SMUs at one site within the masseter muscle during pain in comparison with control was observed during the tasks and some of these changes were different to the changes occurring at the other site. There were no changes in thresholds of SMU firing nor in SMU firing rates between pain and control trials. Inter-individual variability in the motor response to pain was observed at the two different sites of the masseter. Discussion and Conclusions: In general, the data are not consistent with the earlier models of pain-motor interactions, but provide support for more recent models proposing a re-organization of motor activity in the presence of pain.

This thesis aimed to investigate the effects of experimentally induced jaw-muscle pain on the movements and electromyographic activity of jaw and head-neck during chewing in healthy subjects. Kinematic variables related were analyzed: (1) the masticatory sequence (duration, number of cycles masticatory and frequency); (2) the chewing cycle: time of opening, closing and occlusal phase; maximum range of motion and vertical, medial-lateral, anteroposterior and three-dimensional speed of jaw during the phases of opening and closing; maximum amplitude of displacement and head-neck three-dimensional speed during the phases of opening and closing jaw; maximum variation of the cervical flexion-extension angle while chewing; relationship between jaw and head-neck three-dimensional movement. The electromyography variables of the masticatory cycle analyzed were: inactive and active time of the masseter muscles in the side of work and balancing; muscle activation amplitude (MAA) of the masseter and ECM muscles, during active and inactive periods; activation symmetry of the masseter muscles and ECM; coactivation and correlation between masseter MAA and the ECM side of balancing work, during the active period. The study included 28 male volunteers, mean age of 20.6 years. Kinematic data were obtained from Qualisys System and electromyographic data via wireless sensors Delsys. Records were conducted during unilateral chewing wine gum before and after monosodium glutamate solution injections (pain-inducing substance) and normal saline (control). The order and the side of the applications were randomized and separated by a minimum of 45 min. The records before and after experimental procedures were analyzed by t test and Wilcoxon test for dependent variables and the Spearman correlation coefficient was used to analyze the relationship between mandibular and head-neck variables. As a result, it was observed that pain incited reduction on range of mid-lateral movement during the closing jaw, on vertical and three-dimensional speed during the opening and mid-lateral speed during the opening and closing of the masticatory cycle, reduction on MAA masseter muscle side job during the active period prescribed and increased activation symmetry between the masseter muscles on the side of balancing work and during the chewing cycle. However, no effect of pain was observed on the kinematic and electromyographic head-neck variables or on the movement relations and MAA or coactivation between the mandibular and head-neck systems. Moderate effect sizes were observed for results of the kinematic variables of mid-lateral amplitude and mid-lateral/vertical mandibular speed, suggesting that these may have clinical relevance in the evaluation of mastication in the presence of acute pain. Small effect sizes were observed in all results of electromyographic variables, limiting generalizability of the results to the population of patients with TMD. In conclusion, in the presence of acute pain of the stomatognathic system adaptations involve mainly local mechanisms, influencing only kinematic parameters and mandibular electromyographic without compensation on the movement and head-neck electromyographic activity.
Esta tese teve como objetivo investigar os efeitos da dor induzida experimentalmente no músculo masseter sobre os movimentos e a atividade eletromiográfica crânio-cervical e mandibular durante a mastigação em indivíduos saudáveis. Foram analisadas variáveis cinemáticas relacionadas: (1) à sequência mastigatória (duração, número de ciclos e frequência mastigatória); (2) ao ciclo mastigatório: duração das fases de abertura, fechamento e fase oclusal; amplitude máxima de movimento e velocidade vertical, médio-lateral, anteroposterior e tridimensional da mandíbula durante as fases de abertura e fechamento; amplitude máxima de deslocamento e velocidade tridimensional crânio-cervical durante as fases de abertura e fechamento mandibular; máxima variação do ângulo de flexo-extensão cervical durante a mastigação; relação entre os movimentos mandibulares e crânio-cervicais tridimensionais. As variáveis eletromiográficas analisadas, durante o ciclo mastigatório, foram: duração do tempo inativo e ativo dos músculos masseteres dos lados de trabalho e balanceio; amplitude de ativação muscular (AAM) dos músculos masseter e esternocleidomastóideo (ECM), durante os períodos ativo e inativo; simetria de ativação dos músculos masseter e ECM; coativação e correlação entre a AAM do masseter e ECM dos lados de trabalho e balanceio, durante o período ativo. Participaram do estudo 28 voluntários do sexo masculino, com média de idade de 20,6 anos. Os dados cinemáticos foram obtidos através do Sistema Qualisys e os dados eletromiográficos por meio de sensores sem fio e eletromiógrafo Delsys. Foram realizados registros em mastigação unilateral de uma bala de goma de consistência firme, antes e depois de injeções de solução de glutamato monossódico (substância indutora de dor) e de solução salina isotônica (controle). A ordem e o lado das aplicações foram randomizados e separados por um intervalo mínimo de 45 minutos. Os dados pré e pós procedimentos experimentais foram analisados pelos testes t e Wilcoxon para variáveis dependentes e o coeficiente de correlação de Spearmann foi utilizado para a análise da relação entre variáveis mandibulares e crânio-cervicais. Como resultados, observou-se que a dor ocasionou redução da amplitude de deslocamento médio-lateral durante o fechamento mandibular; redução das velocidades vertical e tridimensional durante a abertura e velocidade médio-lateral durante a abertura e fechamento do ciclo mastigatório; redução da AAM do músculo masseter do lado de trabalho durante o período ativo e aumento da simetria de ativação entre os músculos masseteres dos lados de trabalho e balanceio durante o ciclo mastigatório. Entretanto, nenhum efeito da dor foi observado sobre as variáveis cinemáticas e eletromiográficas crânio-cervicais ou sobre as relações do movimento, AAM ou coativação entre os sistemas mandibular e crânio-cervical. Tamanhos de efeito moderados foram observados para os resultados das variáveis cinemáticas de amplitude e velocidade mandibular médio-lateral e vertical, sugerindo que estas podem ter relevância clínica na avaliação da mastigação na presença de dor aguda. Tamanhos de efeito pequenos foram observados em todos os resultados das variáveis eletromiográficas, limitando sua generalização para indivíduos com DTM. Em conclusão, na presença de dor aguda, as adaptações do sistema estomatognático envolvem principalmente mecanismos locais, influenciando apenas parâmetros cinemáticos e eletromiográficos mandibulares, sem compensações sobre o movimento e atividade eletromiográfica crânio-cervical.

Stretch-induced muscle damage is a condition resulting in force decline in skeletal muscle after eccentric contractions. The exact mechanisms underlying this decline is unclear but has been attributed to EC-coupling failure. Both μ-calpain and junctophilin-1 are activated during eccentric contractions in single fibres and isolated muscle, however no studies have shown this in blood-perfused muscle. This study used an in vivo model to investigate the roles of μ-calpain and JP-1 in force decline of the tibialis anterior (TA) muscle of wild-type and mdx mice (model for Duchenne muscular dystrophy) during eccentric contractions. The hypothesis was that eccentric contractions would cause calcium influx through stretch-activated channels (SACs) thereby activating μ-calpain and JP-1, disrupting EC-coupling and thus force production. The TA was subjected to 20 eccentric contractions during supramaximal activation and removed after a 30 min recovery. Western blotting was used to detect protein activity. The results show force decline during eccentric contractions is associated with JP-1 proteolysis, but not μ-calpain autolysis. The SAC blocker, streptomycin, was effective in improving force during eccentric contractions but had no effect on JP-1 proteolysis in mdx mice, whilst a second SAC blocker, anti-TRPC-1, had no effect. The results suggest under more physiological conditions, JP-1 proteolysis is independent of calcium influx through SACs and is more likely due to mechanical damage or reactive oxygen species induced SR-calcium release.

Made available in DSpace on 2014-10-09T12:46:05Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:02:09Z (GMT). No. of bitstreams: 1 07534.pdf: 4371715 bytes, checksum: 9ec1fe68c7fae9017a80251be5a75572 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:50:49Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T13:58:55Z (GMT). No. of bitstreams: 1 09630.pdf: 3746433 bytes, checksum: b60e474fd6da4ad82de4d554c143b16b (MD5)
Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia)
IPEN/D-MPLO
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Osteopaths use muscle energy techniques (MET) to reduce pain, to increase muscle length and to increase joint range of motion. Few investigations have focused on applications of MET and to date the temporomandibular joint (TMJ) has been completely overlooked. This study aimed to determine the effect of a specific MET technique and therapeutic jaw exercises on pain of the temporomandibular region. This study investigated whether changes occurred immediately after application of the treatment protocol and if those changes were maintained over the following thirty minutes and one week later. Twenty one subjects with an inter-incisal range of mouth opening of less than or equal to 40mm were randomly assigned to either a TMJ exercise group, MET group or to a control group. Participants underwent either a specific isometric MET to the muscles of mandibular elevation, therapeutic jaw exercises or recieved no treatment at all. Visual Analogue Scales were used to measure perceived pain and were recorded before and after either intervention. Initially post treatment pain scores increased in those persons who participated in the TMJ exercises. All other pain scores decreased following treatment however these changes were not statistically significant. The results of this study indicated that further investigation into the effects of both MET and TMJ exercises on pain is required and to allow the full effectiveness of MET and TMJ exercises to be explored the need to conduct research on purely symptomatic patients is vital. This minor thesis was written by a post-graduate student as part of the requirements of the Master of Health Science (Osteopathy) program.

Osteopaths use muscle energy techniques (MET) to reduce pain, to increase muscle length and to increase joint range of motion. Few investigations have focused on applications of MET and to date the temporomandibular joint (TMJ) has been completely overlooked. This study aimed to determine the effect of a specific MET technique and therapeutic jaw exercises on pain of the temporomandibular region. This study investigated whether changes occurred immediately after application of the treatment protocol and if those changes were maintained over the following thirty minutes and one week later. Twenty one subjects with an inter-incisal range of mouth opening of less than or equal to 40mm were randomly assigned to either a TMJ exercise group, MET group or to a control group. Participants underwent either a specific isometric MET to the muscles of mandibular elevation, therapeutic jaw exercises or recieved no treatment at all. Visual Analogue Scales were used to measure perceived pain and were recorded before and after either intervention. Initially post treatment pain scores increased in those persons who participated in the TMJ exercises. All other pain scores decreased following treatment however these changes were not statistically significant. The results of this study indicated that further investigation into the effects of both MET and TMJ exercises on pain is required and to allow the full effectiveness of MET and TMJ exercises to be explored the need to conduct research on purely symptomatic patients is vital. This minor thesis was written by a post-graduate student as part of the requirements of the Master of Health Science (Osteopathy) program.