Orientador: Vanessa Monteiro Pedro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-03T23:41:36Z (GMT). No. of bitstreams: 1 Semeghini_TatianaAdamov_D.pdf: 2521486 bytes, checksum: 66bbbe5501501dd84c2354d69d48a0a4 (MD5) Previous issue date: 2004 / Resumo: Embora a co-ativação da musculatura cervical durante a movimentação da mandíbula tenha sido estudada na literatura, esta situação ainda é pouco descrita quando comparados voluntários clinicamente normais e portadores de disfunções musculares. O objetivo deste trabalho foi estudar eletromiograficamente a co-ativação bilateral do músculo esternocleidomastoideo em relação aos Mm. Da mastigação em voluntários clinicamente normais e em portadores de bruxismo. Para a coleta do sinal mioelétrico foi utilizado um eletromiógrafo (*Lynx Eletronics) formado por um módulo condicionador de sinais de 12 bits de resolução, filtro tipo Butterworth (10,6 - 509 Hz) com ganho de 100 vezes, e placa conversora A/D, colocado dentro de uma Gaiola Eletrostática de Faraday. O registro mioelétrico foi realizado pelo software Aqdados, com apresentação simultânea dos canais usados e freqüência de amostragem de 1000 Hz, instalado em um computador 486 DX padrão. O sinal foi captado por eletrodos ativos diferenciais simples, formados por duas barras retangulares de prata paralelas, espaçadas por 10mm. e fixas entre si. A impedância de entrada dos eletrodos foi de 10G¿OMEGA¿, CCMR de 130 dB e 2pF, com ganho de 100 vezes. Foram também utilizados no estudo: eletrodo de referência; esparadrapos impermeáveis; Parafilme M (American National Can TM); metrônomo (Picollo - Winter), régua milimetrada. O sinal eletromiográfico foi coletado em três situações: a) isotonia dos músculos da mastigação; b) CIVM dos músculos da mastigação; c) CIVM do M. ECM. Os dados foram avaliados estatisticamente pelos testes ANOVA - Medidas Repetidas e Teste T para dados não pareados, de acordo com a situação estudada. Os resultados evidenciaram a presença da co-ativação do M. ECM em ambos grupos estudados e a análise dos valores médios de RMS bruto dos Mm. da mastigação revelou diferenças estatisticamente significativas entre os entre os grupos estudados nas variáveis músculos, lados e situações, validando os critérios de inclusão da amostra adotados nesta pesquisa. Em voluntários clinicamente normais, a ativação do M. ECM foi significativamente menor durante a isotonia que na isometria dos Mm. da mastigação, enquanto que em portadores de bruxismo, estas diferenças não foram verificadas. Na CIVM dos Mm. da mastigação, evidenciou-se uma diminuição das porcentagens bilaterais de co-ativação do M. ECM em relação à porção anterior do M. temporal, além da diminuição da ativação do músculo masseter e um aumento da ativação do músculo temporal em portadores de bruxismo, quando. comparados aos voluntários clinicamente normais. Comparando os valores de ativação do M. ECM nos movimentos mandibulares à sua CIVM, verificou-se uma diminuição de ativação muscular do lado direito em voluntários portadores de bruxismo. Os resultados desta pesquisa, sob suas condições experimentais realizadas, permitiram concluir que houve co-ativação do M. esternocleidomastoideo durante a movimentação mandibular e que esta parece sofrer influência das alterações dos músculos da mastigação em voluntários portadores de bruxismo, embora seja perceptível a necessidade de realização de mais estudos sobre o tema / Abstract: Although cervical muscles co-activation during jaw movements has been studied, this verification is stilllittle described in literature when are compared healthy subjects and patients with muscular dysfunction. The aim of this study was to verify by surface electromyography the bilateral co-activation of the sternocleidomastoid (SCM) muscle regarding to chewing muscles in healthy and bruxism volunteers. To record myoelectric signs, has been used a 16 channel signal conditioner with 12 bits dynamic band resolution (*Lynx Eletronics), Butterworth-type band pass filter (10,6-509 Hz) with gain of 100 times, and A/D converter board, placed inside of an Electrostatic Cage of Faraday. The myoelectric signs were displayed through by Aqdados Software installed in an Ibm-pc 486 DX2, that have showed simultaneous presentation of the used channels, each one with frequency of sampling of 1000 Hz. The signal was caught by simple active electrodes, formed by two rectangular and parallel silver bars, spaced for 10 mm. and fixed between it. The electrodes impedance of input was of 10G, 130 dB of CMRR and 2pF, with 100 times of gain. The materiaIs also used in this study were: reference electrode; adhesive tapes; Parafilm-M (American National Can¿POT. TM¿),metronome (Picollo-Winter) and milimetric ruler. The myoelectric signal was collected in three positions: a) chewing movements; b) clenching movements; c) isometric contraction of SCM muscles. The data has been evaluated statistically by ANOVA-repeated measures and impaired T tests, on accordance with the studied situation. The results have evidenced the presence of SCM coactivation in both groups and the analysis of RMS average values by chewing muscles have showed significant statistical differences between groups referring muscles, sides and situations analyzed, witch may be valid the criteria of sample inclusion adopted on this research. In healthy volunteers, the SCM co-activation was significantly fewer during chewing that in clenching, while that in bruxism subjects, these differences have not been verified. During clenching, a reduction of SCM co-activation referred as temporalis anterior muscle was proven, beyond the reduction of masseter muscle with an increase of temporalis anterior muscle activation has been observed in bruxism subjects. Comparing the values of SCM activation on jaw movements with its maximal isometric contractions, has been verified a significant reduction of muscular activity in right side on bruxism subjects. The results of this research, under those experimental conditions, have allowed concluding that the sternocleidomastoid coactivation during the jaw movements was verified in humans and that this seems to suffer influences from muscular alterations caused by bruxism. Thus, it is perceivable the necessity of accomplishment of more studies about this subject / Doutorado / Anatomia / Doutor em Biologia Buco-Dental

Due to the complex nature of jaw movements, three-dimensional (3D) movement recording provide information about the jaw movement capacity. The aim of the present report was to test the reliability of measuring lower jaw movements using a 3D movement recording system and to calculate the lower jaw movement volume. Lower jaw movements, recorded by 3D optoelectronic movement analysis system (MacReflex®) was compared with reference values from a digital caliper. Pre-tests were performed to develop a software to calculate the lower jaw movements in separate dimensions and its volume. Pilot tests with two test persons followed to register the lower jaw movements and calculate lower jaw movement volume. The results indicate low reliability of lower jaw movements measured by movement recording system compared with reference values from digital caliper, reflected by delta values (D = max-min). The values from the movement recording system indicate high variability reflected by higher levels of standard deviation for movement recorded values compared with digital caliper and by percentage values calculated from the differences between mean values of movement recording and digital caliper. The calculated lower jaw movement volume was 10.3 cm3 and 17.2 cm3 for the test persons, respectively. Conclusively, the results imply that further testing of the method is needed with larger series and test-retest reliability analysis to evaluate the possibility to improve accuracy of tracing jaw movements with recording device. The 3D-movement recording system together with the software could be used for calculation of lower jaw movement volume but its accuracy could not be validated.

A deeper understanding of both movement control and the effects of nociceptor inputs on our motor systems is critical for proper clinical diagnosis of musculo-skeletal dysfunctions and for development of novel rehabilitation schemes. In the jaw system, masticatory movements are produced by a central pattern generator (CPG) located in the brainstem. Considerable efforts have been made in deciphering this neuronal network. The present thesis contributes towards an increasingly detailed understanding of its essential elements, and presents a hypothesis of how deep somatic pain (i.e. muscle pain) may be evoked and interferes with the masticatory CPG circuitry. In Paper I, the expression of c-Fos-like protein was used as a molecular marker to visualize brainstem neurons that were active during induced fictive mastication in the anesthetized and paralyzed rabbit. Our findings provide a previously lacking detailed record of the neuronal populations that form the masticatory motor pattern. Certain cells were located in brainstem areas previously suggested to be involved in the masticatory CPG. However, it was a new finding that neurons in the dorsal part of the trigeminal main sensory nucleus (NVsnpr-d) may belong to this circuitry. Paper II focused on the discovered neurons in NVsnpr in an in vitro slice preparation from young rats.  Intracellular recordings allowed us to define two cell types based on their response to depolarizing current. Microstimulation applied to the trigeminal motor nucleus, its reticular border, the parvocellular reticular formation and the nucleus reticularis pontis caudalis, elicited postsynaptic potentials in 81% of the neurons tested. Responses obtained were predominately excitatory and sensitive to gluta-matergic antagonists DNQX or/and APV. Some inhibitory and biphasic responses were also evoked. Bicuculline methiodide or strychnine blocked the IPSPs indicating that they were mediated by GABAA or glycinergic receptors. About one third of the stimulations activated both types of neurons antidromically. Neurons in NVsnpr-d seem to gather all the conditions that can theoretically account for a role in masticatory rhythm generation. In Paper III, the masticatory model system was used to investigate the possible role of muscle spindle primary afferents in development of persistent musculoskeletal pain. Following intramuscular acidic (pH 4.0) saline injections of rat masseter muscles, in vitro whole cell recordings were done from jaw closing muscle spindle somata located in the trigeminal mesencephalic nucleus (NVmes). Compared to control neurons, the somata of afferents exposed to acid had more hyperpolarized membrane potentials, more hyperpolarized thresholds for firing, high frequency membrane oscillations and ectopic bursting of action potentials. These changes in membrane properties lasted for up to 35 days. Within the same time frame experi-mental animals showed hypersensitivity to touch on the skin covering the injected muscle. Similar saline injections also resulted in a significant increase of activity dependent c-Fos expression in NVmes neurons compared to controls. Immuno-fluorescence and lectin binding studies indicated that small-caliber muscle afferents containing known nociceptor markers (CGRP, SP, P2X3, TRPV1 and IB4) and expressing glutamate receptors are found close to the annulo-spiral endings of the NVmes afferents. Combined, our new observations support the hypothesis that excessive release of glutamate, within muscle spindles due to ectopically evoked antidromic action potentials, could lead to development of persistent musculoskeletal pain by activation and/ or sensitization of adjacent muscle afferent nociceptors.