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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Determinação da área alargada posterior ao retratamento do canal radicular com instrumentos de níquel-titânio / Determination of the enlarged area after retreatment of the root canal with nickel-titanium instruments.

Pereira, Larissa Ernesto 27 July 2018 (has links)
O objetivo do presente estudo foi determinar a área alargada posterior ao retratamento do canal radicular com instrumentos de níquel-titânio em imagens de tomografia computadorizada de feixe cônico. Sessenta raízes mesiais de molares inferiores foram selecionadas e submetidas a tomografia computadorizada de feixe cônico(TCFC) em 4 períodos de: antes do preparo (T1), após o preparo (T2), após o retratamento (T3) e após a complementação do retratamento (T4). Após a TCFC inicial (T1), os dentes foram submetidos ao protocolo de abertura coronária e exploração dos canais com lima manual tipo K n.15, preparados com instrumentos ProTaper Next (até X3: # 30.07), e submetidos novamente a TCFC (T2); A seguir foram obturados pela técnica híbrida de Tagger com cimento AH Plus, e submetidos a 1000 ciclos de termociclagem simulando um período de 12 meses. Subsequentemente, os espécimes foram distribuídos de acordo com os protocolos de desobturação do canal radicular, em três grupos (n=10): G1- Protaper Universal Retratamento (D1: #30.09; D2: #25.08; D3: #20.07;); G2- Mtwo Retratamento (#25.05) e G3- DRaCe (DR1: #30.10; DR2: #25.04). Após a desobturação, os espécimes foram submetidos novamente à TCFC (T3). Em seguida, foram submetidos ao protocolo de complementação para remoção do material obturador, em três grupos (n=10): G1, G2 e G3: PT next X4: #40.06. A seguir os espécimes foram submetidos novamente à TCFC (T4) para avaliação da área alargada do canal radicular. A média e o desvio padrão das variáveis quantitativas foram obtidas. A normalidade dos dados foi avaliada pelo teste de Kolmogorov-Smirnov. As variáveis foram avaliadas pelo Teste-t para amostras pareadas para avaliar a diferença entre a área desgastada entre o preparo (Tomografia 2) e o retratamento (Tomografia 4). As variáveis foram avaliadas pelo Teste de Análise de Variância (ANOVA) post hoc Tukey para a comparação entre Protaper-R (grupo 1), Mtwo-R (grupo 2) e D- Race (grupo 3). Foram considerados significativos valores de p < 0,05. A análise de variância evidenciou diferença estatisticamente significante em relação aos grupos em canal mesiovestibular em nível 2 mm abaixo de furca p<0,038 e em canal mesiovestibular em nível 4 mm abaixo de furca p<0,005. Evidenciou também diferença estatisticamente significante em relação aos grupos 1, 2 e 3 em canal mesiovestibular em nível 2 mm abaixo de furca após o retratamento p<0,028. A diferença média da área alargada entre o preparo e o retratamento em canais mesiovestibulares comparando os grupos Protaper-R, Mtwo-R e D-race evidenciou diferença estatisticamente significante em todos os grupos (p<0,000 e p<0,029) e em canais mesiolinguais valores entre p<0,000 e p<0,029. Conclui-se que as técnicas de complementação avaliadas aumentaram a área do canal radicular, contribuindo para a remoção do remanescente de material obturador, sendo que o sistema Protaper-R ® permitiu maior desgaste. Embora tenha havido ampliação da área do canal radicular em níveis determinados, nenhuma das técnicas avaliadas foram capazes de remover completamente o material obturador dos canais radiculares / The objective of the present study was to determine the enlarged area after retreatment of the root canal with nickel-titanium instruments in conical beam computed tomography images. Sixty mesial roots of mandibular molars were selected and submitted to concomitant computed tomography (CBCT) in 4 periods of: before preparation (T1), after preparation (T2), after retreatment (T3) and after completing retreatment (T4). After the initial CBCT (T1), the teeth were submitted to the protocol of coronary opening and exploration of channels with manual file type K n.15, prepared with ProTaper Next instruments (up to X3: # 30.07), and again submitted to CBCT); They were then filled by the Tagger hybrid technique with AH Plus cement and submitted to 1000 cycles of thermocycling simulating a period of 12 months. Subsequently, the specimens were distributed according to root canal clearance protocols, in three groups (n = 10): G1 Protaper Universal Retreatment (D1: # 30.09; D2: # 25.08; D3: # 20.07;); G2- Mtwo Retreatment (# 25.05) and G3- DRaCe (DR1: # 30.10; DR2: # 25.04). After disintegration, the specimens were again submitted to TCFC (T3). Afterwards, they were submitted to the complementation protocol to remove the obturator material, in three groups (n = 10): G1, G2 and G3: PT next X4: # 40.06. Afterwards the specimens were again submitted to TCFC (T4) for evaluation of the enlarged area of the root canal. The mean and standard deviation of the quantitative variables were obtained. The normality of the data was evaluated by the Kolmogorov-Smirnov test. The variables were evaluated by the t-Test for paired samples to evaluate the difference between the worn area between the preparation (Tomography 2) and the retreatment (Tomography 4). The variables were evaluated by the Tukey post-hoc ANOVA for the comparison between Protaper- R (group 1), Mtwo-R (group 2) and D-Race (group 3). Values of p <0.05 were considered significant. The analysis of variance showed a statistically significant difference in relation to the groups in mesiobuccal channel at level 2 mm below furca p <0.038 and in mesiobuccal channel at level 4 mm below furca p <0.005. There was also a statistically significant difference in relation to groups 1, 2 and 3 in mesiobuccal channel at level 2 mm below furcation after retreatment p <0.028. The mean difference in the wide area between preparation and retreatment in mesiobuccal canals comparing the Protaper-R, Mtwo-R and D-race groups showed a statistically significant difference in all groups (p <0.000 and p <0.029) and in mesiolinguistic channels values between p <0.000 and p <0.029. It was concluded that the complementation techniques evaluated increased the root canal area, contributing to the removal of the remainder of the obturator material, and the Protaper-R ® system allowed for greater wear. Although there was enlargement of the root canal area at determined levels, none of the techniques evaluated were able to completely remove the obturator material from the root canals
2

Investigation, design and implementation of circular-polarised antennas for satellite mobile handset and wireless communications. Simulation and measurement of microstrip patch and wire antennas for handheld satellite mobile handsets and investigations of polarization polarity, specific absorption rate, and antenna design optimization using genetic algorithms.

Khalil, Khaled January 2009 (has links)
The objectives of this research work are to investigate, design and implement circularly-polarized antennas to be used for handheld satellite mobile communication and wireless sensor networks. Several antennas such as Quadrifilar Spiral Antennas (QSAs), two arm Square Spiral and stripline or coaxially-fed microstrip patch antennas are developed and tested. These antennas are investigated and discussed to operate at L band (1.61-1.6214GHz) and ISM band (2.4835-2.5GHz) A substantial size reduction was achieved compared to conventional designs by introducing special modifications to the antenna geometries. Most of the antennas are designed to produce circularly-polarized broadside-beam except for wireless sensor network application a circularly-polarized conical-beam is considered. The polarization purity and Specific Absorption Rate (SAR) of two dual-band antennas for satellite-mobile handsets next to the human head are investigated and discussed, using a hybrid computational method. A small distance between the head and the handset is chosen to highlight the effects of the relatively high-radiated power proposed from this particular antenna. A Genetic Algorithm in cooperation with an electromagnetic simulator has been introduced to provide fast, accurate and reliable solutions for antenna design structures. Circularly-polarized quadrifilar helical antenna handset and two air-dielectric microstrip antennas were studied. The capabilities of GA are shown as an efficient optimisation tool for selecting globally optimal parameters to be used in simulations with an electromagnetic antenna design code, seeking convergence to designated specifications. The results in terms of the antenna size and radiation performance are addressed, and compared to measurements and previously published data.
3

Investigation, design and implementation of circular-polarised antennas for satellite mobile handset and wireless communications : simulation and measurement of microstrip patch and wire antennas for handheld satellite mobile handsets and investigations of polarization polarity, specific absorption rate, and antenna design optimization using genetic algorithms

Khalil, Khaled January 2009 (has links)
The objectives of this research work are to investigate, design and implement circularly-polarized antennas to be used for handheld satellite mobile communication and wireless sensor networks. Several antennas such as Quadrifilar Spiral Antennas (QSAs), two arm Square Spiral and stripline or coaxially-fed microstrip patch antennas are developed and tested. These antennas are investigated and discussed to operate at L band (1.61-1.6214GHz) and ISM band (2.4835-2.5GHz) A substantial size reduction was achieved compared to conventional designs by introducing special modifications to the antenna geometries. Most of the antennas are designed to produce circularly-polarized broadside-beam except for wireless sensor network application a circularly-polarized conical-beam is considered. The polarization purity and Specific Absorption Rate (SAR) of two dual-band antennas for satellite-mobile handsets next to the human head are investigated and discussed, using a hybrid computational method. A small distance between the head and the handset is chosen to highlight the effects of the relatively high-radiated power proposed from this particular antenna. A Genetic Algorithm in cooperation with an electromagnetic simulator has been introduced to provide fast, accurate and reliable solutions for antenna design structures. Circularly-polarized quadrifilar helical antenna handset and two air-dielectric microstrip antennas were studied. The capabilities of GA are shown as an efficient optimisation tool for selecting globally optimal parameters to be used in simulations with an electromagnetic antenna design code, seeking convergence to designated specifications. The results in terms of the antenna size and radiation performance are addressed, and compared to measurements and previously published data.
4

Analyse de la morphologie buccofaciale et des voies aériennes supérieures chez des porteurs de prothèses complètes souffrant des troubles du sommeil

Chassé, Véronique 02 1900 (has links)
No description available.

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