Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-06T17:32:29Z No. of bitstreams: 1 rodrigofalcisantos.pdf: 3181366 bytes, checksum: 26ae7d9a4c2057c4eaf0d4de25c69495 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-08T14:40:37Z (GMT) No. of bitstreams: 1 rodrigofalcisantos.pdf: 3181366 bytes, checksum: 26ae7d9a4c2057c4eaf0d4de25c69495 (MD5) / Made available in DSpace on 2016-06-08T14:40:37Z (GMT). No. of bitstreams: 1 rodrigofalcisantos.pdf: 3181366 bytes, checksum: 26ae7d9a4c2057c4eaf0d4de25c69495 (MD5) Previous issue date: 2013-03-21 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Este ensaio pré-clínico se propôs avaliar e comparar o volume ósseo na interface enxerto/leito receptor, utilizando o etil-cianoacrilato (Super Bonder Flex Gel®) e parafusos de titânio como agentes de fixação na incorporação de enxertos ósseos, verificado por meio de microtomografia computadorizada. Para tal, utilizou-se 12 ratos, da espécie Rattus novergicos albinus, (Wistar), machos adultos com aproximadamente três meses de idade. Os animais foram aleatoriamente divididos em dois grupos de seis, com um grupo controle (grupo Parafuso Titânio – PT), no qual foi utilizado um parafuso de fixação interna rígida para estabilização do enxerto, e um grupo experimental (grupo Super Bonder Flex Gel® - SB) , no qual foi aplicado o adesivo para estabilizar o enxerto ósseo. O procedimento foi realizado sob anestesia geral, removendo-se um enxerto em bloco do osso parietal esquerdo e fixando-o no osso parietal direito na calvária dos animais. Após 30 dias de cirurgia os 12 animais foram submetidos à eutanásia e o material enxertado foi submetido à análise microtomográfica. O teste U de Mann Whitney, não mostrou diferença estatisticamente significativa entre os parâmetros avaliados (volume total-TV, volume ósseo-BV, fração do volume-BV/TV, espessura trabecular-Tb.Th, distância intertrabecular-TB.Sp e número de trabéculas-Tb.N) em ambos os grupos, com exceção da distância entre as trabéculas (Tb.Sp). O grupo SB apresentou uma Tb.Sb significativamente maior (p=0,015). Desta forma pode-se concluir que o exame de microtomografia computadorizada foi capaz de detectar formações de tecido ósseo mineralizado na interface enxerto/leito receptor após 30 dias do experimento. Além disso, o etil-cianoacrilato foi tão eficiente quanto o parafuso de titânio na estabilização e incorporação do enxerto ósseo na calvária de ratos, tanto em relação aos parâmetros volumétricos, quanto em relação aos parâmetros de densidade óssea. / This preclinical trial was developed with the aim of evaluating and comparing the bone volume in the interface bone / graft, using ethyl-cyanoacrylate (Super Bonder Flex Gel ®) and titanium screws as fixing agents in bone graft incorporation, evaluated by computed microtomography. To verify the efficiency of the tested product, 12 adult male rats of the species Rattus novergicos albinus (Wistar) of approximately three months of age were randomly divided into two groups of six rats each. In the control group (PT), a screw internal fixation was used to stabilize the graft. In the experimental group (SB) an adhesive of ethyl- cyanoacrylate was used. Under general anesthesial a block graft was removed from the left parietal bone and fixed on the right parietal bone, in the calvaria of the animal. Thirty days after the surgery, all animals were euthanized and the grafted material analyzed by computed microtomography. The Mann Whitney U test did not show any statistically significant difference between the proposed parameters (Total volume – TV, Bone volume – BV, Bone volume fraction – BV/TV, Trabecular thickness – Tb.Th, Trabecular separation – Tb.Sp and Trabecular number – Tb.N) in both groups, except for the Trabecular separation (Tb.Sp). The SB group presented a Tb.Sb higher than the PT group (p = 0.015) with statistical significance. Therefore, was possible to conclude that the computed microtomography test was able to detect mineralized bone tissue formations in the interface bone / graft after 30 days. Also the volumetric parameters and the parameters of bone density for ethyl-cyanoacrylate was as efficient as the titanium screw in bone graft incorporation in rat calvaria.

Rentgenová počítačová mikrotomografie (CT) je metoda pro trojrozměrné (3D) zobrazování vnitřní struktury objektů. Laboratoř rentgenové počítačové mikro a nanotomografie na CEITEC VUT (Středoevropský technologický institut, Vysoké učení technické v Brně) se zaměřuje zejména na nedestruktivní analýzu v průmyslovém odvětví. Ukázalo se ale, že tato metoda nachází široké uplatnění i v dalších vědeckých oblastech včetně vývojové biologie. Tato práce poskytuje propojení mezi materiálovými a živými vědami. Kompletní proces vedoucí k vytvoření 3D modelu různých anatomických struktur je detailně popsán. Tento postup zahrnuje kontrastování vzorků, samotné CT měření a analýzu dat. Právě zpracování dat je mnohdy považováno za nejdůležitější část v rentgenové počítačové tomografii a proto je této oblasti věnována v práci největší část. Úpravou měřicích parametrů byl dále optimalizován CT přístroj GE v|tome|x L 240 za účelem umožnění automatické segmentace. Navíc je diskutována možnost měření na synchrotronu za účelem zvýšení prostorového rozlišení a diferenciálního kontrastu. Předpokládá se, že v blízké budoucnosti získají průmyslové CT přístroje podobné zobrazovací vlastnosti, a to jak díky nedávnému vývoji v oblasti hardwaru, tak v oblasti zpracování dat.

O presente estudo teve como objetivo principal avaliar as estruturas rúpteis da borda leste da Bacia do Paraná em Santa Catarina, a partir do estudo dos lineamentos estruturais que afetaram as rochas do embasamento, da sucessão ondwânica, das vulcânicas da Formação Serra Geral e das alcalinas associadas ao Domo de Lages e ao Complexo Carbonatítico de Anitápolis. Para atingir estes objetivos, foram efetuados levantamentos de campo de análise estrutural dos lineamentos, integração do arcabouço estrutural a partir de dados geofísicos (aeromagnetometria), análise de imagens do sistema óptico ( Landsat-7 \'ETM POT.+\'), imagens de radar (SRTM-3) e dados de microtomografia computadorizada (\'mü\'CT). Os dados obtidos foram incorporados em um Sistema de Informação Geográfic a (SIG), analisados em conjunto ou separados, e permitiram caracterizar estruturas associadas à tectônica formadora e deformadora da Bacia do Paraná. A tectônica formadora da bacia evidencia um padrão estrutural compativel com o modelo de um \'rifte central\' de direção NE-SW, e a tectônica deformadora revelou estar ligada não apenas a movimentos verticais, mas principalmente a movimentos horizontais capazes de gerar falhas transcorrentes em ambiente intraplaca. Foram caracterizados três eventos tectônicos deformadores da sequência Paleozoica da Bacia do Paraná, que são posteriores as vulcânicas da Formação Serra Geral e as rochas alcalinas do Domo de Lages, a saber: um evento mais antigo (Cretáceo Inferior) com orientação da compressão máxima (\'sigma\'1) ao redor de N -S, observado apenas nas rochas da Formação Serra Geral; um evento de idade intermediária (Cretáceo Superior- Terciário) com compressão máxima (\'sigma\'1) orientada próxima de NE-SW, caracterizado nos três domínios estudados (Escudo Catarinense, Form. Serra Geral e rochas alcalinas); e o último evento de idade mais nova (Neógeno), com a compressão máxima (\'sigma\'1) orientada ao redor de E-W (ESE-WNW), idendificado em dois domínios (Escudo Catarinense e Form. Serra Geral). Os três eventos envolveram a geração de estruturas transcorrentes e podem ser explicados em um contexto geodinâmico associados à: ruptura continental do Gondwana, abertura do Oceano Atlântico, rotação da Placa Sul-America de leste para oeste e subducção na costa oeste da Placa Sul-Americana. Os dois primeiros eventos foram relacionados à tectônica que afetou à margem passiva (transtração) da Placa Sul-Americana, e o último foi relacionado à influência da subducção da Placa d e Nazca sob a Placa Sul-Americana. O processo iniciou-se com a compressão máxima (\'sigma\'1) ao redor de N-S, que gerou transcorrências destrais intracontinentais próximas de NW e transcorrências sinistrais NE associadas com a margem continental rompida. Posteriormente, o campo de compressão máxima (\'sigma\'1) mudou para direção próxima de NE, devido à rotação da Placa Sul-Americana para oeste e, atualmente, devido à influência da compressão da margem ativa da Placa Sul-Americana sobre a Placa de Nazca, instalou-se um campo de compressão máxima (\'sigma\'1) próximo de E-W (transpressão). / The main objective of the present study was to evaluate the brittle structures of the eastern border of Paraná Basin in Santa Catarina State, based on the study of structural lineaments affecting the basement rocks, the Gondwanan succession, the vulcanic rocks from Serra Geral Formation, the alkaline rocks from Lages`s Dome and from Anitápolis Carbonatite Complex. To achieve these goals structural analysis from field data were done, as well as, the integration of the structural framework from geophysical data (aeromagnetometric), image analysis of the o ptical system (Landsat-7 \'ETM POT.+\'), radar (SRTM-3) and data from computed microtomography (\'mü\'CT). The data were incorporated into a Geographic Information System (GIS) and analyzed together or separately. The data obtained allowed to characterize tectonic structures associated with the formation and the deformation of the Paraná Basin. The tectonic development of the basin shows a structural pattern compatible with the model of a central rift in the NE-SW and the tectonic related to deformation of the basin revealed not only to be linked with vertical movements, but also the horizontal movements can generate transcurrent faults in intraplate environment. Three tectonic events were characterized and related to the deformation of the Paraná Basin, after Serra Geral Formation, thus described: one older (Lower Cretaceous) with maximum stress (\'sigma\'1) oriented around NS trend, observed only in the rocks from Serra Geral Formation, an intermediate age (Upper Cretaceous-Tertiary) with maximum stress (\'sigma\'1) oriented next to NE-SW, identified in the three studied domains (Santa Catarina Shield, Serra Geral Formation and alkaline rocks), and the last younger (Neogene), with maximum stress (\'sigma\'1) oriented around EW (ESE-WNW) identified in two areas (Santa Catarina Shield and Serra Geral Form.). The three events involving transcurrent faults can be explained in a geodynamic context associated to: breaking of Gondwana, opening of the Atlantic Ocean, rotation of the South America Plate from east to west and the subduction of the Nazca plate under the South-American Plate. The first two events are related to the tectonic of the passive margin (transtension) and the latter related to the influence of the subduction of the Nazca Plate under the South American Plate. The process began with maximum stress (\'sigma\'1) oriented around NS trend, which generated intracontinental transcurrent dextral faults near NW and NE sinistral faults associated with the continental margin broken. Later, the maximum stress (\'sigma\'1) was oriented near NE due to the rotation of the South American Plate to the west, and now due to the influence of the compression of the active margin of the South American Plate on the Nazca Plate, the maximum stress (\'sigma\'1) is near EW (transpression).

O presente estudo teve como objetivo principal avaliar as estruturas rúpteis da borda leste da Bacia do Paraná em Santa Catarina, a partir do estudo dos lineamentos estruturais que afetaram as rochas do embasamento, da sucessão ondwânica, das vulcânicas da Formação Serra Geral e das alcalinas associadas ao Domo de Lages e ao Complexo Carbonatítico de Anitápolis. Para atingir estes objetivos, foram efetuados levantamentos de campo de análise estrutural dos lineamentos, integração do arcabouço estrutural a partir de dados geofísicos (aeromagnetometria), análise de imagens do sistema óptico ( Landsat-7 \'ETM POT.+\'), imagens de radar (SRTM-3) e dados de microtomografia computadorizada (\'mü\'CT). Os dados obtidos foram incorporados em um Sistema de Informação Geográfic a (SIG), analisados em conjunto ou separados, e permitiram caracterizar estruturas associadas à tectônica formadora e deformadora da Bacia do Paraná. A tectônica formadora da bacia evidencia um padrão estrutural compativel com o modelo de um \'rifte central\' de direção NE-SW, e a tectônica deformadora revelou estar ligada não apenas a movimentos verticais, mas principalmente a movimentos horizontais capazes de gerar falhas transcorrentes em ambiente intraplaca. Foram caracterizados três eventos tectônicos deformadores da sequência Paleozoica da Bacia do Paraná, que são posteriores as vulcânicas da Formação Serra Geral e as rochas alcalinas do Domo de Lages, a saber: um evento mais antigo (Cretáceo Inferior) com orientação da compressão máxima (\'sigma\'1) ao redor de N -S, observado apenas nas rochas da Formação Serra Geral; um evento de idade intermediária (Cretáceo Superior- Terciário) com compressão máxima (\'sigma\'1) orientada próxima de NE-SW, caracterizado nos três domínios estudados (Escudo Catarinense, Form. Serra Geral e rochas alcalinas); e o último evento de idade mais nova (Neógeno), com a compressão máxima (\'sigma\'1) orientada ao redor de E-W (ESE-WNW), idendificado em dois domínios (Escudo Catarinense e Form. Serra Geral). Os três eventos envolveram a geração de estruturas transcorrentes e podem ser explicados em um contexto geodinâmico associados à: ruptura continental do Gondwana, abertura do Oceano Atlântico, rotação da Placa Sul-America de leste para oeste e subducção na costa oeste da Placa Sul-Americana. Os dois primeiros eventos foram relacionados à tectônica que afetou à margem passiva (transtração) da Placa Sul-Americana, e o último foi relacionado à influência da subducção da Placa d e Nazca sob a Placa Sul-Americana. O processo iniciou-se com a compressão máxima (\'sigma\'1) ao redor de N-S, que gerou transcorrências destrais intracontinentais próximas de NW e transcorrências sinistrais NE associadas com a margem continental rompida. Posteriormente, o campo de compressão máxima (\'sigma\'1) mudou para direção próxima de NE, devido à rotação da Placa Sul-Americana para oeste e, atualmente, devido à influência da compressão da margem ativa da Placa Sul-Americana sobre a Placa de Nazca, instalou-se um campo de compressão máxima (\'sigma\'1) próximo de E-W (transpressão). / The main objective of the present study was to evaluate the brittle structures of the eastern border of Paraná Basin in Santa Catarina State, based on the study of structural lineaments affecting the basement rocks, the Gondwanan succession, the vulcanic rocks from Serra Geral Formation, the alkaline rocks from Lages`s Dome and from Anitápolis Carbonatite Complex. To achieve these goals structural analysis from field data were done, as well as, the integration of the structural framework from geophysical data (aeromagnetometric), image analysis of the o ptical system (Landsat-7 \'ETM POT.+\'), radar (SRTM-3) and data from computed microtomography (\'mü\'CT). The data were incorporated into a Geographic Information System (GIS) and analyzed together or separately. The data obtained allowed to characterize tectonic structures associated with the formation and the deformation of the Paraná Basin. The tectonic development of the basin shows a structural pattern compatible with the model of a central rift in the NE-SW and the tectonic related to deformation of the basin revealed not only to be linked with vertical movements, but also the horizontal movements can generate transcurrent faults in intraplate environment. Three tectonic events were characterized and related to the deformation of the Paraná Basin, after Serra Geral Formation, thus described: one older (Lower Cretaceous) with maximum stress (\'sigma\'1) oriented around NS trend, observed only in the rocks from Serra Geral Formation, an intermediate age (Upper Cretaceous-Tertiary) with maximum stress (\'sigma\'1) oriented next to NE-SW, identified in the three studied domains (Santa Catarina Shield, Serra Geral Formation and alkaline rocks), and the last younger (Neogene), with maximum stress (\'sigma\'1) oriented around EW (ESE-WNW) identified in two areas (Santa Catarina Shield and Serra Geral Form.). The three events involving transcurrent faults can be explained in a geodynamic context associated to: breaking of Gondwana, opening of the Atlantic Ocean, rotation of the South America Plate from east to west and the subduction of the Nazca plate under the South-American Plate. The first two events are related to the tectonic of the passive margin (transtension) and the latter related to the influence of the subduction of the Nazca Plate under the South American Plate. The process began with maximum stress (\'sigma\'1) oriented around NS trend, which generated intracontinental transcurrent dextral faults near NW and NE sinistral faults associated with the continental margin broken. Later, the maximum stress (\'sigma\'1) was oriented near NE due to the rotation of the South American Plate to the west, and now due to the influence of the compression of the active margin of the South American Plate on the Nazca Plate, the maximum stress (\'sigma\'1) is near EW (transpression).

The study of internal structure of materials has always been an essential issue in a variety of application fields, from the medical radiology to the materials science. X-ray computed microtomography (with both conventional and synchrotron radiation sources) has a great potential for these purposes because its three-dimensional and non destructive nature as well as the fact that it does not require any sample preparation and it allows to study samples under stress or after consecutive treatments. The recent developments of new X-ray sources with innovative imaging techniques, as well as novel high resolution detectors, allow moving forward the maximum achievable resolution of this technique to a few micrometers or even less. This contributed to increase its application in biomedical purposes, but also to raise the need for quantitative analysis of the reconstructed data. Indeed in most of the cases a quantitative characterization of the samples microstructures is needed to better understand their physical and chemical behavior, the effects of manufacturing process or the response to stress. Dedicated software packages have been developed to perform a geometrical and morphological characterization of the samples texture and to evaluate some typical parameters commonly used to classify porous media such as porosity, cell size distribution, connectivity and anisotropy. In this work two case studies have been considered for the application of a quantitative analysis approach to microtomography datasets: the first concerns the characterization of bone ingrowth within tissue engineering scaffolds, while the second is related to the extraction of morphological descriptors for the architecture of human skull bones. It will be shown how suitable image processing and analysis techniques are able to effectively quantify significant parameters such as the trabecular thickness of the skull bones as well as the porosity and the degree of connectivity of bone tissue engineering scaffolds. Similar quantitative analysis methods applied to microtomography images have to be considered as an effective methodology for a comprehensive characterization of other biomedical samples.

The use of Computerised microtomography (CμT) in biomedical research is well established, with most applications developed at synchrotron facilities. The possibility to non-invasively monitor morphological changes in biological samples, makes it an attractive technique in biomedicine. However, high absorbed doses and long examination times are a disadvantage that limits the possibilities of performing longitudinal examinations. The aim of this work was to optimise CmT using conventional X-ray tubes for applications in non-destructive material testing and for skeleton research in small animals (rat). A calculational model of the imaging system was developed and used to optimise the relation between image quality, expressed as the signal-to-noise ratio (SNR) in detecting a contrasting detail, and imaging time in material testing. The model was modified to optimise the relation between the SNR in detecting a trabecular detail in cancelleous bone and the mean absorbed dose in spongiosa and skin for (rat) tibia and femur. Gastrectomized Sprague-Dawley rats were used to initiate osteoporotic changes. In order to detect differences in between gastrectomized rats and controls, spatial resolutions of 150 mm or better were needed. The minimum absorbed doses in femur spongiosa at SNR = 5 were 1mGy - 700 mGy at spatial resolutions from 100 mm to10 mm. In femur skin, the corresponding minimum absorbed doses were 2 mGy - 2000 mGy. Corresponding values for tibia were 0.3 mGy - 300 mGy for both spongiosa and skin (spatial resolution of 100 mm to10 mm). Taking 0.5 Gy as the tolerance limit for the spongiosa dose, longitudinal studies with six repeated examinations will be possible at a spatial resolution of 25 mm in femur and 17 examinations in tibia.

This work deals with processing and analysis of micro-CT images of dental-canals filled by~two materials (AH-plus and NaMPC). For that reason, six dog-teeth were scanned in the X-Ray Micro CT Research Lab. The main aim was to produce an algorithm (in Matlab) that evaluates the quality of filling of dental canals (quality of filling materials). The algorithm performs the segmentation of dental canals and calculates their borders. Also, the algorithm measures the percentage contacts of filling materials with dental walls. Moreover, the algorithm provides masks of dental canals according to requirements of the commercial program VG Studio, that evaluates the porosity of filling materials. The results of percentage contacts and porosities show on not-remarkable differences of tested filling materials.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação de Mestrado do programa de Pós-Graduação em Ciência e Tecnologia dos Materiais é apresentado um estudo para a caracterização do concreto reforçado com fibras de polipropileno e de aço pela análise das imagens de microtomografia computadorizada por transmissão de raios X (μCT). Foram produzidos corpos de prova de concreto para determinar a sua resistência mecânica à compressão. As imagens foram obtidas no sistema Skyscan, modelo 1174, reconstruídas e analisadas. Foi possível observar na análise das imagens a estrutura da fibra de aço dispersa na matriz do concreto e quantificá-las pelo programa de análise de imagens Ctan e perceber um ganho na resistência mecânica em relação ao concreto sem fibras. Não foi feito a quantificação das amostras de fibras de polipropileno dispersas na matriz de concreto, mas foi observada a presença de aglomerados dessa fibra que resultaram na perda da resistência mecânica em relação ao concreto sem fibras. / In this dissertation Masters Program Graduate in Science and Technology of Materials is presented a study for characterization of concrete reinforced with polypropylene fibers and steel by image analysis of computed microtomography X ray transmission (μCT). Concrete samples were produced to determine their mechanical resistance to compression. The images were obtained in the SkyScan model 1174, reconstructed and analyzed. It was possible, in image analysis, to observe the structure of steel fiber dispersed in the concrete matrix and quantify them by image analysis program Ctan and observed a gain in strength compared to concrete fiber less. The quantification was not did to samples of polypropylene fibers dispersed in the matrix of concrete, but we observed the presence of clusters fibers resulting in the loss of mechanical strength compared to concrete fiber less.

Ultra high performance fibre reinforced concrete (UHPFRC) is a relatively new fibre reinforced cementitious composite and has become very popular in construction applications. Extensive experimental studies have been conducted, demonstrating its superior properties such as much higher strength, ductility and durability than conventional fibre reinforced concrete (FRC) and high performance concrete. However, the material's damage and fracture mechanisms at meso/micro scales are not well understood, limiting its wider applications considerably. This study aims at an in-depth understanding of the damage and fracture mechanisms of UHPFRC, combining microscale in-situ X-ray computed tomography (µXCT) experiments and mesoscale image-based numerical modelling. Firstly, in-situ µXCT tests of small-sized UHPFRC specimens under wedge splitting loading were carried out, probably for the first time in the world, using an in-house designed loading rig. With a voxel resolution of 16.9µm, the complicated fracture mechanisms are clearly visualised and characterised using both 2D images and 3D volumes at progressive loading stages, such as initiating of micro-cracks, arresting of cracks by fibres, bending and pulling out of fibres and spalling of mortar at the exit points of inclined fibres. Secondly, based on the statistics of pores in the µXCT images obtained for a 20mm cube specimen, an efficient two-scale analytical-numerical homogenisation method was developed to predict the effective elastic properties of the UHPFRC. The large number of small pores were first homogenised at microscale with sand and cement paste, using elastic moduli from micro-indentation tests. 3D mesoscale finite element models were built at the second scale by direct conversion of the µXCT images, with fibres and large pores were faithfully represented. The effects of the volume fraction and the orientation of steel fibres on the elastic modulus were investigated, indicating that this method can be used to optimise the material micro-structure. Thirdly, 3D mesoscale finite element models were built for the specimen used in the in-situ µXCT wedge splitting test, with embedded fibre elements directly converted from the µXCT images. The fracture behaviour in the mortar was simulated by the damage plasticity model available in ABAQUS. Finally, 2D mesoscale finite element models were developed to simulate the fracture behaviour of UHPFRC using cohesive interface elements to simulate cracks in the mortar, and randomly distributed two-noded 1D fibres and connector elements to simulate the pull-out behaviour of fibres. This approach offers a link between the fibres pull-out behaviour and the response of the whole composite at the macroscale, thus it can be used to conduct parametric studies to optimise the material properties.

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 (α=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 (α=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.