No preparo dos canais radiculares, eminentemente os curvos, a abordagem cérvico-apical amplamente difundida promovendo a dilatação da região cervical do canal radicular previamente à atuação de instrumentos em sua região apical constitui técnica e inegavelmente uma forma adequada, tanto do ponto de vista mecânico como microbiológico, de interagir com o espaço endodôntico em busca de uma experiência bem sucedida e previsível. De outra forma, os mais recentes instrumentos endodônticos, muito mais flexíveis em decorrência das novas ligas de baixo módulo de elasticidade empregadas em sua fabricação e dotados de novos índices de conicidade, surgem melhorando tais perspectivas. Desde o surgimento da liga de Níquel-Titânio na Endodontia, na década de oitenta, uma gama imensa de instrumentos desta derivados e para serem empregados com dispositivos mecânicos, eletromecânicos ou pneumocânicos, têm reavivado a esperança de se obter um dispositivo ideal que simulando a cinemática manual supere as limitações operacionais decorrentes, principalmente, da configuração anatômica do canal radicular. Assim, neste experimento verificou-se o desempenho de quatro diferentes recursos técnicos no desgaste da região cervical do canal radicular. Constituíram-se quatro amostras, cada qual composta de 10 espécimes (raízes mésio-vestibulares de primeiros molares superiores), para serem preparadas com (i) Brocas Gates-Glidden, (ii) Brocas Largo-Peeso, (iii) ProFile® .04/.06 & Orifice Shapers e (iv) Pow-R Coronal Shapers. Imagens digitais obtidas antes e após o preparo do canal radicular foram analisadas também digitalmente estudo morfométrico computadorizado avaliando-se a variação das áreas das mesmas em função do desgaste promovido pelos referidos instrumentos. Todos os instrumentos produziram desgaste de ambas as paredes, mesial e distal, do canal radicular na região analisada. A análise estatística das variações de área para o fator parede mesial não mostrou diferenças estatisticamente significantes entre os grupos experimentais para =5%. No entanto quando da comparação dos grupos experimentais para o fator parede distal verificou-se diferenças estatisticamente significantes entre os grupos #1 e #3 para =5%. Ainda, para o fator área total (paredes mesial e distal) verificou-se diferenças estatisticamente signifcantes entre os grupos #3 e #4 para =5%. Concluiu-se que todos os instrumentos testados produzem desgaste tanto da parede mesial como da parede distal do canal radicular e, conseqüentemente, da estrutura dentinária global da região cervical do canal radicular. Por outro lado verificou-se uma tendência da Broca Gates-Glidden em promover maior desgaste da parede distal que o Sistema ProFile® .04/.06 & Orifice Shapers e do Sistema Pow-R Coronal Shapers em promover maior desgaste da estrutura toal que o Sistema ProFile® .04/.06 & Orifice Shapers. / Nowadays is common sense among endodontists that in root canal preparation, mainly the curved ones, the crown-down approach enlarging the cervical third prior instrumentation of the apical third regions provides better interaction between the instrument and the canal walls than the conventional methods. Technically it provides an adequate form to achieve the best and predictable results in cleaning and shaping the root canal system. Additionally the most recent nickel-titanium made endodontic instruments more flexible than the stainless steel instruments and the new taper design have been appeared to improve the endodontic panorama. Since the introduction of the nickel-titanium alloy in Endodontics by Walia et al. in 1988 a number of instruments produced by such alloy in conjunction with the engines new generation have brought new perspectives to deal tridimensionally with the still challenger endodontic space. In this study the performance of four different instruments in the root canal cervical third enlargement was evaluated. Four experimental groups comprised by ten upper molars mesiobuccal roots each were prepared by either (i) Gates bur, (ii) Largo bur, (iii) Profile® .04/.06 & Orifice Shapers or (iv) Pow-R Coronal Shapers. Before and after preparation digitally acquired images were evaluated for area changes within both mesial and distal root canal walls. All instruments produced some amount of wear in both walls and the distals have changed more than the mesials in most times probably due an excentric performance of all evaluated instruments. Comparison of root canal walls wearing among the four experimental groups showed no statistically significant differences (=5%) for mesial wall. However, statistically analyze (=5%) showed significant differences between Experimental Group #1 (Gates-Glidden burs) and Experimental Group #3 (Profile® .04/.06 & Orifice Shapers) for distal walls with the first showing greater wearing than the latter. Also, the results showed statistically significant differences between Experimental Group #4 (Pow-R & Coronal Shapers) and Experimental Group #3 (Profile® & Orifice Shapers) for the entire structure i.e. mesial and distal walls with the first showing the greater than the latter wearing . It was concluded that all tested instruments wear so the mesial as the distal root canal walls. Experimental results have showed that in first upper molaras mesiobuccal roots Gates-Glidden bur for distals and Pow-R nickel-titanium instruments for both walls, i.e. the cervical dentin entire structure, are supposed to wear more root canal cervical third dentin than the others instruments which they were compared.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2017-01-04T09:35:23Z No. of bitstreams: 2 Tese - Iussif Mamede Neto - 2016.pdf: 8414229 bytes, checksum: dbd825fbd28378443533fac54c7a09c1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-04T09:59:04Z (GMT) No. of bitstreams: 2 Tese - Iussif Mamede Neto - 2016.pdf: 8414229 bytes, checksum: dbd825fbd28378443533fac54c7a09c1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-04T09:59:04Z (GMT). No. of bitstreams: 2 Tese - Iussif Mamede Neto - 2016.pdf: 8414229 bytes, checksum: dbd825fbd28378443533fac54c7a09c1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-11-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Objective: To evaluate transportation (T) and centering ability (CA) of root canal preparations using continuous or reciprocating nickel-titanium endodontic files. Material and methods: Ninety-six mesiobuccal root canals of mandibular first and second molars were randomly divide into 6 groups (n=16) according to the rotary file used: Group 1- ProTaper Next®; Group 2- ProTaper Gold®; Group 3- Mtwo®; Group 4- BioRaCe®; Group 5- WaveOne Gold®; Group 6- Reciproc®. Root canals were prepared according to manufacturer’s instructions. Cone-beam computed tomography scans were obtained before and after canal preparation. Measurements were made at five different points: 2, 3 and 4 mm from the apex and 2, 3 and 4 mm below furcation. Transportation and centering ability were analyzed following the recommendations made by Gambill et al. (1996). Results: The greatest mesiodistal (MD) transportation (T) was found for Reciproc® files (p<0.05), and the greatest buccolingual (BL) T, for Reciproc®, ProTaper Gold® and ProTaper Next® files (p<0.05). The greatest mesiodistal (MD) centering ability (CA) was found for BioRaCe® files (p<0.05), and the greatest buccolingual (BL) CA, for BioRaCe® and Mtwo® files (p<0.05). Conclusion: All systems produced root canal transportation. No file system achieved perfect CA of root preparation. Reciproc® files had the greatest MD T and BL T. BioRaCe® files had the greatest MD CA, whereas BL CA was similar for BioRaCe® and Mtwo® files. / Objetivo: Avaliar o índice de transporte (IT) e a capacidade de centralização (CC) do preparo do canal radicular com instrumentos endodônticos de níquel-titânio acionados em rotação contínua e reciprocante. Materiais e métodos: Noventa e seis canais mesiovestibulares de molares inferiores (primeiro e segundo) foram aleatoriamente divididos em 06 grupos (n=16), de acordo com o instrumento rotatório utilizado: Grupo 1- ProTaper Next®; Grupo 2- ProTaper Gold®; Grupo 3- Mtwo®; Grupo 4- BioRaCe®; Grupo 5- WaveOne Gold®; Grupo 6- Reciproc®. A técnica de preparo do canal radicular obedeceu a orientação dos fabricantes. Tomografia computadorizada de feixe cônico foi realizada antes e após o preparo dos canais radiculares. Foram estabelecidos 06 níveis para a realização das mensurações nas imagens: 2, 3 e 4 mm aquém do vértice radicular e 2, 3 e 4 mm abaixo da furca. O índice de transporte e a capacidade de centralização foram analizados conforme proposto por Gambill et al. (1996). Resultados: O maior IT no sentido mesiodistal (MD) foi observado com o Reciproc® (p<0,05), enquanto que no sentido vestíbulolingual (VL) foram verificados com Reciproc®, ProTaper Gold® e ProTaper Next® (p<0,05). Os maiores valores de CC(MD) e (VL) foram observados com os sistemas BioRaCe® (p<0,05) e BioRaCe® e Mtwo® (p<0,05), respectivamente. Conclusão: Todos os sistemas promoveram transporte do canal radicular. Nenhum instrumento mostrou capacidade de centralização do preparo perfeita. O Reciproc® obteve os valores maiores de IT(MD) e (VL). O sistema BioRaCe® apresentou a maior CC(MD), enquanto que no sentido (VL) o BioRaCe® e Mtwo® mostraram capacidades similares.

The aim of this study was to evaluate the mechanical properties of engine-driven Nickel-Titanium instruments manufactured by different thermal treatments. In the first part of this study, 60 reciprocating instruments were used (n=20): Reciproc R25 (REC 25.08), Unicone L25 (UNC 25.06) e Prodesign R 25 (PDR 25.06). The cyclic flexural fatigue resistance was performed measuring the time to failure in an artificial stainless steel canal with a 60º angle and a 5 mm radius of curvature (n=10). The torsional test was performed according to ISO 3630-1, measuring the torque and angle of rotation at failure in the 3 mm from the tip portion (n=10). Additionally, the fractured surface of each instrument was examined by scanning electron microscopy (SEM) to assess the topographic features of the fractured surface. Data were analyzed using one was analysis of variance ANOVA and Tukey test, the level of significance was set at 5%. The results of the cyclic flexural fatigue showed that PDR 25.06 presented significantly higher values than the other groups (P<0.05). REC 25.08 showed higher fatigue resistance than UNC 25.06 (P<0.05). In relation to the torsional test, the PDR 25.06 presented the lowest torque load than REC 25.08 and UNC 25.06 (P<0.05). In addition, there was no significant difference between REC 25.08 and UNC 25.06 (P>0.05). The PDR 25.06 and UNC 25.06 showed higher angular rotation until fracture than REC 25.08 (P<0.05). No difference was found between PDR 25.06 and UNC 25.06. All the instruments showed typical topographic features of cyclic flexural and torsional fatigue. The second part of this study evaluated the cyclic flexural and torsional fatigue resistance of reciprocating instruments Reciproc Blue (RB 25.08), WaveOne Gold Primary (WOG 25.07) and Prodesign R 25 (PDR 25.06) (n=20). The cyclic flexural fatigue test was performed with the same previsoly described device, using a root curvature with 60º and a 5 mm radius (n=10) and the torsional test was performed according to ISO 3630-1 (n=10). The fractured surface of each instrument was examined by scanning electron microscopy (SEM). Data were analyzed using one was analysis of variance ANOVA and Tukey test, the level of significance was set at 5%. The results of the cyclic flexural fatigue test showed that PDR 25.06 presented significantly higher values than the other groups (P<0.05). RB 25.08 showed higher fatigue resistance than WOG 25.07 (P<0.05). The torsional test showed that PDR 25.06 had lowed torsional load (P<0.05). No difference was found between RB 25.08 and WOG 25.07 (P>0.05). In relation the angular rotation, the PDR 25.06 showed higher angular rotation values than RB 25.08 and WOG 25.07 (P<0.05). RB 25.08 presented higher angular values than WOG 25.07 (P<0.05). All the instruments showed typical topographic features of cyclic flexural and torsional fatigue. The third part of this study was to evaluate the torsional fatigue resistance of NiTi rotary glide path instruments. The torsional test was performed according to ISO 3630-1, measuring the torque and angle of rotation at failure in the 3 mm from the tip portion. A total of 56 glide path instruments were used (n=8): Logic 25.01 (LOG 25.01), Logic CM 25.01(LOG CM 25.01), Proglider 16.02 (PGD 16.02), Hyflex GPF 15.01, 15.02, 20.02 (HGPF) and Mtwo 10.04. The fractured surface of each instrument was examined by scanning electron microscopy (SEM). Data were analyzed using one was analysis of variance ANOVA and Tukey test, the level of significance was set at 5%. The results showed that LOG 25.01 had a significantly higher torsional load than the other groups (P<0.05). The PGD 16.02 had significantly difference in comparison with HGPF 15.01 and 15.02 (P<0.05). LOG CM 25.01 had higher torsional load than HGPF 15.01 and 15.02 (P<0.05). No difference was found among Mtwo 10.04, HGPG 15.01, 15.02 and 20.02. In relation the angular rotation, LOG CM 25.01 and HGPF 15.01 presented the highest values (P<0.05). PGD 16.02 had the lowest values (P<0.05) followed by Mtwo 10.04. LOG 25.01 had higher angle of rotation than PGD 16.02 and Mtwo 10.04 (P<0.05). All the instruments showed typical topographic features of torsional fatigue. / O objetivo deste estudo foi avaliar o comportamento mecânico de instrumentos mecanizados de Níquel-Titânio (NiTi) fabricados com diferentes tratamentos térmicos. Na primeira parte do estudo foram utilizados 60 instrumentos reciprocantes para a realização dos teste de fadiga cíclica flexural e torcional (n=20): Reciproc R25 (REC 25.08), Unicone L25 (UNC 25.06) e Prodesign R 25 (PDR 25.06). O teste de fadiga cíclica flexural foi realizado com o objetivo de mensurar o tempo para a fratura dos instrumentos em um canal artificial de aço inoxidável com curvatura com 60º de angulação e 5 mm de raio (n=10). Para o teste de torção, os 3 mm inicias das pontas dos instrumentos foram fixadas em um aparelho de torção (n=10), de acordo com a norma ISO 3630-1. Este teste foi realizado com o objetivo de mensurar o torque máximo e o ângulo de rotação suportado pelos instrumentos até sua fratura. Adicionalmente, todos os fragmentos dos instrumentos fraturados foram examinados em microscopia eletrônica de varredura (MEV) para avaliar as características topográficas da superfície da área da fratura. A análise-estatística foi realizada utilizando o teste de análise de variância com um fator ANOVA e teste de Tukey, o nível de significância foi de 5%. Os resultados de fadiga cíclica flexural demonstraram que o PDR 25.06 apresentou maior tempo para a fratura do que os outros grupos (P<0.05). O instrumento REC 25.08 apresentou maior resistência a fadiga cíclica flexural do que o UNC 25.06 (P<0.05). O teste de torção demonstrou que o PDR 25.06 apresentou significantemente menor resistência torcional do que o REC 25.08 e UNC 25.06 (P<0.05). Além disso, não houve diferença entre REC 25.08 e UNC 25.06. Com relação ao ângulo de rotação, o PDR 25.06 e UNC 25.06 apresentaram diferença significante quando comparado ao REC 25.08. Não houve diferença entre PDR 25.06 e UNC 25.06 (P>0.05). Todos os instrumentos apresentaram característica topográficas típicas de fadiga cíclica flexural e torcional. Na segunda parte deste estudo avaliou-se a fadiga cíclica flexural e torcional dos instrumentos reciprocantes Reciproc Blue R25 (RB 25.08), WaveOne Gold Primary (WOG 25.07) e Prodesign R 25 (PDR 25.06) (n=20). O teste de fadiga cíclica flexural foi realizado com dispositivo descrito anteriormente, utilizando curvaturas de 60º e 5 mm de raio (n=10). O teste de torção foi realizado de acordo com a norma ISO 3630-1 (n=10). Todos os fragmentos dos instrumentos fraturados foram examinados em microscopia eletrônica de varredura (MEV) para avaliar as características topográficas da superfície da área da fratura. A análise-estatística foi realizada utilizando o teste de análise de variância com um fator (ANOVA) e teste de Tukey, o nível de significância foi de 5%. Os resultados de fadiga cíclica flexural demonstraram que o PDR 25.06 apresentou a maior resistência a fadiga cíclica flexural do que dos outros grupos (P<0.05). O RB 25.08 apresentou maior tempo para à fratura do que o WOG 25.07 (P<0.05). O teste de torção, o PDR 25.06 apresentou a menor resistência à torção do que os outros grupos (P<0.05). Não houve diferença significante entre RB 25.08 e WOG 25.07 (P>0.05). Em relação ao ângulo de rotação, o PDR 25.06 apresentou maiores valores quando comparados com RB 25.08 e WOG 25.07. O RB 25.08 apresentou diferença significante quando comparado com WOG 25.07. Todos os instrumentos apresentaram características topográficas típicas de fadiga cíclica flexural e torcional. Na terceira parte deste estudo avaliou-se a resistência torcional de instrumentos empregados para patência do canal radicular, de acordo com a norma ISO 3630-1. Foram utilizados 56 instrumentos rotatórios (n=8): Logic 25.01 (LOG 25.01), Logic CM 25.01 (LOG CM 25.01), Proglider 16.02 (PGD 16.02), Hyflex GPF 15.01, 15.02, 20.02 (HGPF) e Mtwo 10.04. Os fragmentos dos instrumentos fraturados foram examinados em microscopia eletrônica de varredura (MEV) para avaliar as características topográficas da superfície da área da fratura. A análise-estatística foi realizada utilizando o teste de análise de variância com um fator ANOVA e teste de Tukey, o nível de significância foi de 5%. Os resultados demonstraram que o LOG 25.01 apresentou significantemente maior resistência torcional do que os demais grupos (P<0.05). O grupo da PGD 16.02 apresentou diferença significante quando comparado com HGPF 15.01 e 15.02 (P<0.05). O LOG CM 25.01 apresentou maior resistência torcional do que o grupo do HGPF 15.01 e 15.02 (P<0.05). Não houve diferença significante entre os intrumentos Mtwo 10.04 e HGPF 15.01, 15.02 e 20.02. Com relação ao ângulo de rotação, o LOG CM 25.01 e HGPF 15.01 apresentaram os maiores valores (P<0.05). O PGD 16.02 apresentou o menor valor de todos os grupos (P<0.05) seguido pelo Mtwo 10.04. O LOG 25.01 apresentou maiores ângulos de rotação do que o PGD 16.02 e Mtwo 10.04 (P<0.05). Todos os instrumentos apresentaram característica topográficas típicas de fadiga torcional. As características da secção transversal, tipo de núcleo, taper e o tratamento térmico possuem forte influência sobre as propriedades mecânicas dos instrumentos de NiTi. No entanto, o tratamento térmico é um dos fatores primordiais para maior flexibilidade dos instrumentos. O instrumento PDR 25.06 apresentou maior resistência à fadiga cíclica flexural e maior ângulo de rotação no teste de torção do que todos os outros instrumentos reciprocantes avaliados. No entanto, menor resistência torcional. Os intrumentos LOG 25.01 apresentaram maior resistência torcional e o LOG CM 25.01 maiores ângulos de rotação.

In an effort to mitigate damage caused by earthquakes to the built environment, civil engineers have been commissioned to research, design, and build increasingly robust and resilient structural systems. Innovative means to accomplish this task have emerged, such as integrating Shape Memory Alloys (SMAs) into structural systems. SMAs are a unique class of materials that have the ability to spontaneously recover strain of up to 8%. With proper placement in a structural system, SMAs can act as superelastic "structural fuses", absorbing large deformations, dissipating energy, and recentering the structure after a loading event. Though few applications have made it into practice, the potential for widespread use has never been better due to improvements in material behavior and reductions in cost. In this research, three different SMA-based structural applications are developed and tested. The first is a tension/compression damper that utilizes nickel-titanium (NiTi) Belleville washers. The second is a partially restrained beam-column connection utilizing NiTi bars. The third is an articulated quadrilateral bracing system utilizing NiTi wire bundles in parallel with c-shape dampers. Each system was uniquely designed to allow a structure to undergo large drift demands and dissipate energy while retaining strength and recentering ability. This exploratory work highlights the potential for SMA-based structural applications to enhance seismic structural performance and community resilience.

Objectif : il a été rapporté que l’utilisation d’agents prophylactiques fluorés pouvait favoriser la corrosion galvanique au sein des alliages de titane. L’objectif de la présente étude était d’évaluer l’effet d’un rince-bouche fluoré sur les propriétés mécaniques de fils en nickel-titane (NiTi) et de fils en cuivre-nickel-titane (CuNiTi) lorsque ces derniers sont couplés à des boîtiers de compositions différentes (boîtiers de marques Smartclip, Clarity, et Sprint). Matériels et Méthodes : 90 segments de fils en NiTi et 90 segments de fils en CuNiTi ont été chacun couplés à 2 boîtiers de chaque marque. Chaque assemblage fil-boîtiers a été par la suite incubé pendant 3 heures à 37°C, soit dans une solution de fluore neutre (Fluorinse™ 0,05% NaF), soit dans une solution de salive artificielle (solution contrôle). Suite à l’incubation, les échantillons étaient nettoyés avec de l’eau déshydrogénée, les fils séparés des boîtiers et montés sur un support pour subir un test de pliage en trois points en milieu humide (salive artificielle) à 37°C. Les modules d’élasticité ainsi que les limites conventionnelles d’élasticité en activation et en désactivation ont été mesurés et comparés. Des analyses de Variance (ANOVA) et des comparaisons post-hoc avec la correction de Bonferronni ont été utilisées pour comparer les groupes entre eux (α = 0,05). Résultats : L’utilisation d’un rince-bouche fluoré a produit une réduction du module d’élasticité et de la limite conventionnelle d’élasticité en activation et en désactivation pour les fils en NiTi ; cependant, cet effet a été modulé par le type de boîtier auquel le fil a été couplé. Les propriétés mécaniques de fils en CuNiTi n’ont pas été affectées par le fluor, ou par le type de boîtier utilisé. Conclusions : L’utilisation d’un rince-bouche fluoré modifie les propriétés mécaniques des fils en NiTi seulement. Cet effet est modulé par le boîtier auquel le fil en NiTi est couplé. A la différence des autres études publiées dans la littérature, nos résultats ne nous permettent pas de conclure que la modification des propriétés mécaniques des fils en NiTi entrainerait obligatoirement un allongement de la durée du traitement orthodontique. Mots clés : Fluor, fils nickel-titane, boîtiers orthodontiques, corrosion galvanique, propriétés mécaniques. / Aim: it has been reported that the use of fluoride prophylactic agents can cause galvanic corrosion of the titanium based alloys used in orthodontics. The purpose of the present study was to investigate the effects of a fluoride mouthrinse on the mechanical properties of nickel-titanium (NiTi) and copper–nickel-titanium (CuNiTi) orthodontic archwires that have been coupled with different types of orthodontic brackets (Smartclip, Clarity, and Sprint brackets). Materials and Methods: 90 segments of NiTi and 90 segments of CuNiTi archwires were tested. Every segment was coupled with 2 brackets of each brand. The wire–bracket assembly obtained was incubated, at 37°C for three hours either in a solution of a commercially available mouthwash (Fluorinse™ 0,05% NaF), or in a solution of artificial saliva (control). Following the incubation, the wires were separated from the brackets, rinsed, mounted on a stainless steel support and placed in a waterbath of artificial saliva at 37°C. A 3-point bending test was made to calculate the loading and unloading elastic modulus and yield strength of the wires. Analysis of variance (ANOVA) and post hoc comparisons were made using Bonferronni’s correction to identify the statistically significant differences (α = 0,05). Results: The use of a fluoridated mouthrinse reduced the loading and unloading elastic modulus and yield strength of the NiTi wires. This reduction, however, varies with the type of bracket that was coupled with the wire. The mechanical properties of the CuNiTi wires were not modified by the use of the fluoride rinse or by the type of bracket to which they were coupled. Conclusions : The use of a fluoride mouthrinse alters the mechanical properties of NiTi wires only. This effect varies with the type of bracket that was in contact with the wire. However our results do not allow us to conclude that the alteration of the mechanical properties of the wires would necessarily imply a prolongation of the orthodontic treatment time. Key words: Fluoride, nickel-titanium archwires, galvanic corrosion, mechanical properties,orthodontic brackets.

This doctoral study consists of three parts. In the first part, structural and electronic properties of Al_kTi_lNi_m (k+l+m=2,3) microclusters have been investigated by performing density functional theory (DFT) calculations within the B3LYP [which comprises the Becke-88 exchange functional and the correlation functional of Lee, Yang, and Parr] and the effective core potential (ECP) level. Dimers and trimers of the elements aluminum, titanium, and nickel, and their binary and ternary combinations have been studied in their ground states. The optimum geometries, possible dissociation channels, vibrational properties, and electronic structure of the clusters under study have been obtained. In the second part, after an empirical potential energy function (PEF) has been parametrized for the AlTiNi ternary system, stable (minimum-energy) structures of Al_kTi_lNi_m (k+l+m=4) microclusters have been determined by molecular dynamics (MD) simulations. The energetics of the microclusters in 1K and 300 K have been discussed. By performing, again, DFT calculations (within the B3LYP and ECP level), the possible dissociation channels and electronic properties of the obtained clusters have been calculated. In the last part, using the empirical PEF parametrized previously for the AlTiNi ternary system, minimum-energy structures of Al_nTi_nNi_n (n= 1-16) ternary alloy nanoparticles have been determined by performing MD simulations. The structural and energetic features of the obtained nanoparticles have been investigated.

O objetivo do presente trabalho foi avaliar, em microtomografia computadorizada (CT), o preparo de canais de molares inferiores com diferentes sistemas acionados a motor. Foram selecionadas 58 raízes mesiais patentes, de diâmetro anatômico correspondente a #10. Para a avaliação em TC, um anel de aço inoxidável foi confeccionado nos moldes do suporte para amostra do microtomógrafo, para que servisse de fôrma para a inclusão das raízes em resina Duralay, a fim de padronizar a posição do espécime no escaneamento inicial e final. Os canais foram preparados com os sistemas Reciproc R25 (n=16); WaveOne Primary File (n=16); Twisted File (n=14), e HyFlex (n=12). Após serem escaneados, foram reconstruídos tridimensionalmente e avaliados quantitativamente quanto à variação de volume (mm3), área de superfície (mm2) e structure model index (SMI). Foi, ainda, realizada a avaliação qualitativa das seções transversais por terço e por quadrante (MV, ML, DV, DL), sendo avaliado o toque de paredes. Os dados paramétricos foram analisados estatisticamente pelos testes ANOVA e t para amostras pareadas (&#945;=5%). Não foi observada diferença estatística nos parâmetros quantitativos avaliados para Reciproc (142,77 76,75; 42,22 19,22; e 14,68 17,69, respectivamente); WaveOne (105,09 64,82; 29,54 19,21; 14,81 9,10, respectivamente); Twisted File (111,83 43,09; 33,31 18,40; 9,16 6,57, respectivamente), e HyFlex (151,74 149,37; 43,08 41,44; 10,80 8,52, respectivamente) (p=0,423). Dentro de cada grupo, foi observada diferença significante entre os resultados pré e pós-operatórios. O teste não paramétrico de Kruskal Wallis foi aplicado para a avaliação relativa ao toque de paredes. Foi observado que o sistema HyFlex apresentou a maior porcentagem de toques (82,3 13,1), seguido por Reciproc (81,3 16,9), Twisted File (78,3 14,4) e, por fim, WaveOne (76,9 21,7) (p>0,05). Em relação aos terços não foi observada diferença significativa (p=0,424). Os resultados da avaliação dos quadrantes intergrupo não demonstraram diferenças, porém indicaram tendência do preparo em direção à parede distal no terço cervical. Ao final, pôde-se concluir que os sistemas testados se equivalem quanto ao preparo de canais mesiais de molares inferiores; porém, nenhuma das técnicas foi capaz de tocar completamente em todas as paredes do canal radicular. / The aim of this work was to analyze, in X-ray computed microtomography (CT), the root canal preparation of mandibular molars with different engine driven systems. 58 mesial roots were selected, of anatomic diameter corresponding to #10. For the analysis in TC, a stainless steel ring was manufactured in the same shape as the brace for CT sampling, in order to serve as a mold to insert the roots in Duralay resin, so as to standardize the position of the specimen in the initial and final scanning. The canals were prepared with the Reciproc R25 (n=16), WaveOne Primary File (n=16), Twisted File (n=14) and HyFlex (n=12) systems. After being scanned, they were three-dimensionally reconstructed and quantitatively evaluated as regards the variation of volume (mm3), surface area (mm2) and structure model index (SMI). In addition, the qualitative evaluation of the cross sections by third and by quadrant (MV, ML, DV, DL) was carried out, along with the wall touching evaluation. The parametric data were statistically analyzed by ANOVA and t-tests for paired samples (&#945;=5%). No statistical difference was observed in the qualitative parameters evaluated for Reciproc (142.77 76.75; 42.22 19.22; and 14.68 17.69; respectively), WaveOne (105.09 64.82; 29.54 19.21; 14.81 9.10; respectively), Twisted File (111.83 43.09; 33.31 18.40; 9.16 6.57; respectively) and HyFlex (151.74 149.37; 43.08 41.44; 10.80 8.52) (p=0,423). Significant difference was observed within each group between the pre- and post-results. The Kruskal-Wallis non-parametric test was applied for the evaluation as regards root canal wall touching. At the end, we observed that the HyFlex system presented the highest touching rate (82.3 13.1), followed by the Reciproc (81.3 16.9), Twisted File (78.3 14.4) and, finally, WaveOne (76.9 21.7) systems (p>0.05). As for the thirds, was not observed any significant difference (p=0.424). The results of the evaluation in the intergroup quadrants did not show any difference; however, they showed that there was a preparation trend towards the distal wall in the cervical third. At the end, it can conclude that the systems tested are equivalent as regards the preparation of mesial canals of mandibular molars, but none of the techniques was capable of fully touching all root canal walls.

This thesis work was conducted in the Department of Mechanical Engineering at the Cape Peninsula University of Technology (CPUT) and was submitted towards the partial fulfilment of the Masters Degree in Technology: Mechanical Engineering. / Recent years have witnessed a tremendous growth and significant advances in “smart” composites and “smart” composite structures. These smart composites integrate active elements such as sensors and actuators into a host structure to create improved or new functionalities through a clever choice of the active elements and/or a proper design of the structure. Such composites are able to sense a change in the environment and make a useful response by using an external feedback control system. Depending on their applications, smart composites usually make use of either the joint properties of the structure or the properties of the individual elements within the composites. The accumulation in the understanding of materials science and the rapid developments in computational capabilities have provided an even wider framework for the implementation of multi-functionality in composites and make “smart” composites “intelligent”.

O objetivo do presente trabalho foi avaliar, em microtomografia computadorizada (CT), o preparo de canais de molares inferiores com diferentes sistemas acionados a motor. Foram selecionadas 58 raízes mesiais patentes, de diâmetro anatômico correspondente a #10. Para a avaliação em TC, um anel de aço inoxidável foi confeccionado nos moldes do suporte para amostra do microtomógrafo, para que servisse de fôrma para a inclusão das raízes em resina Duralay, a fim de padronizar a posição do espécime no escaneamento inicial e final. Os canais foram preparados com os sistemas Reciproc R25 (n=16); WaveOne Primary File (n=16); Twisted File (n=14), e HyFlex (n=12). Após serem escaneados, foram reconstruídos tridimensionalmente e avaliados quantitativamente quanto à variação de volume (mm3), área de superfície (mm2) e structure model index (SMI). Foi, ainda, realizada a avaliação qualitativa das seções transversais por terço e por quadrante (MV, ML, DV, DL), sendo avaliado o toque de paredes. Os dados paramétricos foram analisados estatisticamente pelos testes ANOVA e t para amostras pareadas (&#945;=5%). Não foi observada diferença estatística nos parâmetros quantitativos avaliados para Reciproc (142,77 76,75; 42,22 19,22; e 14,68 17,69, respectivamente); WaveOne (105,09 64,82; 29,54 19,21; 14,81 9,10, respectivamente); Twisted File (111,83 43,09; 33,31 18,40; 9,16 6,57, respectivamente), e HyFlex (151,74 149,37; 43,08 41,44; 10,80 8,52, respectivamente) (p=0,423). Dentro de cada grupo, foi observada diferença significante entre os resultados pré e pós-operatórios. O teste não paramétrico de Kruskal Wallis foi aplicado para a avaliação relativa ao toque de paredes. Foi observado que o sistema HyFlex apresentou a maior porcentagem de toques (82,3 13,1), seguido por Reciproc (81,3 16,9), Twisted File (78,3 14,4) e, por fim, WaveOne (76,9 21,7) (p>0,05). Em relação aos terços não foi observada diferença significativa (p=0,424). Os resultados da avaliação dos quadrantes intergrupo não demonstraram diferenças, porém indicaram tendência do preparo em direção à parede distal no terço cervical. Ao final, pôde-se concluir que os sistemas testados se equivalem quanto ao preparo de canais mesiais de molares inferiores; porém, nenhuma das técnicas foi capaz de tocar completamente em todas as paredes do canal radicular. / The aim of this work was to analyze, in X-ray computed microtomography (CT), the root canal preparation of mandibular molars with different engine driven systems. 58 mesial roots were selected, of anatomic diameter corresponding to #10. For the analysis in TC, a stainless steel ring was manufactured in the same shape as the brace for CT sampling, in order to serve as a mold to insert the roots in Duralay resin, so as to standardize the position of the specimen in the initial and final scanning. The canals were prepared with the Reciproc R25 (n=16), WaveOne Primary File (n=16), Twisted File (n=14) and HyFlex (n=12) systems. After being scanned, they were three-dimensionally reconstructed and quantitatively evaluated as regards the variation of volume (mm3), surface area (mm2) and structure model index (SMI). In addition, the qualitative evaluation of the cross sections by third and by quadrant (MV, ML, DV, DL) was carried out, along with the wall touching evaluation. The parametric data were statistically analyzed by ANOVA and t-tests for paired samples (&#945;=5%). No statistical difference was observed in the qualitative parameters evaluated for Reciproc (142.77 76.75; 42.22 19.22; and 14.68 17.69; respectively), WaveOne (105.09 64.82; 29.54 19.21; 14.81 9.10; respectively), Twisted File (111.83 43.09; 33.31 18.40; 9.16 6.57; respectively) and HyFlex (151.74 149.37; 43.08 41.44; 10.80 8.52) (p=0,423). Significant difference was observed within each group between the pre- and post-results. The Kruskal-Wallis non-parametric test was applied for the evaluation as regards root canal wall touching. At the end, we observed that the HyFlex system presented the highest touching rate (82.3 13.1), followed by the Reciproc (81.3 16.9), Twisted File (78.3 14.4) and, finally, WaveOne (76.9 21.7) systems (p>0.05). As for the thirds, was not observed any significant difference (p=0.424). The results of the evaluation in the intergroup quadrants did not show any difference; however, they showed that there was a preparation trend towards the distal wall in the cervical third. At the end, it can conclude that the systems tested are equivalent as regards the preparation of mesial canals of mandibular molars, but none of the techniques was capable of fully touching all root canal walls.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-06-11T11:47:52Z No. of bitstreams: 2 Dissertação - Ana Paula Pedroso Brito - 2015.pdf: 1014799 bytes, checksum: e2dcf8a46ffc5134b0215684a6190af3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-06-11T11:50:48Z (GMT) No. of bitstreams: 2 Dissertação - Ana Paula Pedroso Brito - 2015.pdf: 1014799 bytes, checksum: e2dcf8a46ffc5134b0215684a6190af3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-06-11T11:50:48Z (GMT). No. of bitstreams: 2 Dissertação - Ana Paula Pedroso Brito - 2015.pdf: 1014799 bytes, checksum: e2dcf8a46ffc5134b0215684a6190af3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-03-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Purpose: to determine flute-to-shank ratio of rotatory nickel-titanium instruments Mtwo® #30/.05, ProTaper® #30/.09, Wizard Navigator® #30/.06 and BioRace® 35/.04. Material and methods: Instruments’ diameter were measured with a digital caliper in the first five flutes and abraded longitudinally by a diamond disk until instrument half diameter was achieved in flutes region. The samples were then fixed in stubs and SEM images were performed at 60X magnification. The flutes and shanks areas were measured, and flute-toshank ratio was achieved using software AxioVision®. Statistical analysis was performed by ANOVA and Tukey’s Test for comparison between groups. Results: There was significant statistical difference for flutes areas. Mtwo® #30/.05 had the higher shank areas and was significantly different from the other instruments, except for Wizard Navigator #30/.06 ate the second flute site. Flute-to-shank ratio showed a 3-28% variation. Conclusions: Flutes dimensions were lower than shanks’. Wizard Navigator® #30/.05 had lower flute-to-shank ratio than other files. / Objetivo: Relacionar a aresta lateral de corte e o núcleo de instrumentos endodônticos de níquel-titânio de rotação contínua Mtwo® #30/.05, ProTaper® #30/.09, Wizard Navigator® #30/.06 e BioRace® 35/.04. Material e métodos: Os instrumentos foram medidos com paquímetro digital para aferição do seu diâmetro nas cinco primeiras arestas de corte e desgastados longitudinalmente com disco diamantado flexível dupla face até atingir metade do diâmetro do instrumento nas regiões das arestas laterais de corte. A seguir, as amostras foram fixadas em stubs e obtidas as imagens por microscopia eletrônica de varredura com aumento de 60X. Foram realizadas mensurações das áreas da aresta lateral de corte e do núcleo, e a razão entre estas medidas utilizando o software AxioVision®. A análise estatística foi realizada por meio da ANOVA e do Teste de Tukey para comparação entre os grupos. Resultados: Houve diferença significativa entre as áreas das arestas para todos os instrumentos. O instrumento Mtwo® #30/.05 apresentou as maiores áreas do núcleo, com diferença significativa para todos os demais instrumentos, à exceção do Wizard Navigator® #30/.06 na região da segunda aresta. A relação entre a área da aresta de corte e do respectivo núcleo mostrou que a aresta representou áreas que variaram de 3% a 28% do núcleo. Conclusões: As dimensões da aresta lateral de corte foram inferiores às do núcleo em todos os instrumentos. O Wizard Navigator® #30/.06 apresentou uma relação entre as dimensões da aresta em relação ao núcleo inferiores aos demais