O objetivo do trabalho foi avaliar as alterações morfológicas bi, tridimensionais, e o transporte em canais mesiais de molares inferiores com curvatura acentuada. Selecionou-se molares inferiores com dois canais e forames independentes, livres de nódulos pulpares, reabsorção interna, tratamento endodôntico prévio, fratura radicular e dentro do padrão de raio e ângulo de curvatura, avaliados pelos exames radiográficos, tomográficos cone bean e microtomográficos. Partiu-se de 393 dentes para selecionar 15 dentro deste padrão morfológico. Esses dentes foram submetidos à microtomografia antes da instrumentação, após o preparo com instrumento Reciproc® R25 e após o preparo por cada lima dos sistemas de complementação (Mtwo e K3). Os dados morfométricos foram analisados pelo programa CTAn e as análises estatísticas foram realizadas utilizando o programa SPSS onde observou-se os seguintes resultados: a análise morfométrica bidimensional mostrou que a área e o perímetro apresentaram aumento gradual a cada milímetro avaliado, partindo do primeiro milímetro apical; houve também aumento gradual de área e de perímetro a cada troca de instrumento de acordo com o que se realizou o preparo biomecânico dentro dos conjuntos de grupos; houve diferença estatisticamente significante de área e de perímetro dos canais radiculares apenas após o preparo com os instrumentos #40 taper 04 e taper 02 (P<0,05). Em relação à distância do ápice, houve diferença estatística de área entre todos os milímetros avaliados (P<0,05). Em relação ao perímetro, não houve diferença entre os milímetros 1 e 2; e, 4 e 5 (P>0,05), entretanto com diferença entre o terceiro milímetro e os demais (P<0,05). As análises morfológicas tridimensionais de volume, área de superfície e SMI (Índice de Modelo Estrutural) do canal radicular, tiveram comportamento semelhante entre os grupos. Os espécimes submetidos à complementação, com instrumentos taper 04 e taper 02, não apresentaram diferença estatística após os preparos (P>0,05), com diferença entre os canais preparados com a R25 e os canais originais (P<0,05). Quando comparados os conjuntos de grupos, nenhum grupo análogo apresentou diferença estatística (P>0,05). Foi analisado o transporte por terços (cervical, médio e apical) e por todo o canal, não sendo detectada diferença estatisticamente significante (P>0,05) entre os terços, nem do canal todo entre a complementação pelos instrumentos taper 04 (Mtwo) e taper 02 (K3). / The purpose of this study was to evaluate the two- and three-dimensional morphological changes, and the transportation that occurs in the mesial canals of mandibular molars with severe curvature. Molars were selected with two independent canals and foramina, no pulpal nodules, internal resorptions, previous endodontic treatment or root fracture and within the standard radius and angle of curvature evaluated by radiographs, cone-beam tomography and microtomography. From the 393 teeth initially selected, 15 fulfilled the selected parameters. The teeth were subjected to microtomography before instrumentation, after instrumentation with Reciproc® R25 and after preparation with each file of the complementary systems (MTwo and K3). The morphometric data were analyzed by CTAn software and the statistical analysis was performed using the SPSS software where the following results were observed. The two-dimensional morphometric analysis showed that the area and the perimeter presented a gradual increase for every evaluated millimeter, starting from the first apical millimeter. There was also a gradual increase in area and perimeter with each change of instrument according to the biomechanical within the sets of groups. There was a statistically significant difference in area and perimeter of root canals after the preparation with the instruments #40 taper 04 and taper 02 (P <0.05). Regarding the distance from the apex area, there was statistically difference among all evaluated millimeters (P <0.05). Regarding the perimeter, there was no difference between 1 and 2 mm, and 4 or 5 (P> 0.05), however with a difference between the third millimeter and the others (P <0.05). The three-dimensional morphological analyses of volume, surface area and root canal SMI (Structural Model Index) of the root canal showed a similar behavior among the groups. The specimens subjected to complementation to the instrumentation with instruments of tapers 04 and 02 showed no statistically significant difference after preparation (P> 0.05), with significant difference between the original and prepared canals (P <0.05). When comparing the sets of groups, no analogue group presented a statistically significant difference (P> 0.05). Transport was analyzed by thirds (cervical, middle and apical) and throughout the canal there, without statistically difference (P> 0.05) among the thirds or between groups with complementation with taper 04 (MTwo) and taper 02 (K3) instruments.

O objetivo do trabalho foi avaliar as alterações morfológicas bi, tridimensionais, e o transporte em canais mesiais de molares inferiores com curvatura acentuada. Selecionou-se molares inferiores com dois canais e forames independentes, livres de nódulos pulpares, reabsorção interna, tratamento endodôntico prévio, fratura radicular e dentro do padrão de raio e ângulo de curvatura, avaliados pelos exames radiográficos, tomográficos cone bean e microtomográficos. Partiu-se de 393 dentes para selecionar 15 dentro deste padrão morfológico. Esses dentes foram submetidos à microtomografia antes da instrumentação, após o preparo com instrumento Reciproc® R25 e após o preparo por cada lima dos sistemas de complementação (Mtwo e K3). Os dados morfométricos foram analisados pelo programa CTAn e as análises estatísticas foram realizadas utilizando o programa SPSS onde observou-se os seguintes resultados: a análise morfométrica bidimensional mostrou que a área e o perímetro apresentaram aumento gradual a cada milímetro avaliado, partindo do primeiro milímetro apical; houve também aumento gradual de área e de perímetro a cada troca de instrumento de acordo com o que se realizou o preparo biomecânico dentro dos conjuntos de grupos; houve diferença estatisticamente significante de área e de perímetro dos canais radiculares apenas após o preparo com os instrumentos #40 taper 04 e taper 02 (P<0,05). Em relação à distância do ápice, houve diferença estatística de área entre todos os milímetros avaliados (P<0,05). Em relação ao perímetro, não houve diferença entre os milímetros 1 e 2; e, 4 e 5 (P>0,05), entretanto com diferença entre o terceiro milímetro e os demais (P<0,05). As análises morfológicas tridimensionais de volume, área de superfície e SMI (Índice de Modelo Estrutural) do canal radicular, tiveram comportamento semelhante entre os grupos. Os espécimes submetidos à complementação, com instrumentos taper 04 e taper 02, não apresentaram diferença estatística após os preparos (P>0,05), com diferença entre os canais preparados com a R25 e os canais originais (P<0,05). Quando comparados os conjuntos de grupos, nenhum grupo análogo apresentou diferença estatística (P>0,05). Foi analisado o transporte por terços (cervical, médio e apical) e por todo o canal, não sendo detectada diferença estatisticamente significante (P>0,05) entre os terços, nem do canal todo entre a complementação pelos instrumentos taper 04 (Mtwo) e taper 02 (K3). / The purpose of this study was to evaluate the two- and three-dimensional morphological changes, and the transportation that occurs in the mesial canals of mandibular molars with severe curvature. Molars were selected with two independent canals and foramina, no pulpal nodules, internal resorptions, previous endodontic treatment or root fracture and within the standard radius and angle of curvature evaluated by radiographs, cone-beam tomography and microtomography. From the 393 teeth initially selected, 15 fulfilled the selected parameters. The teeth were subjected to microtomography before instrumentation, after instrumentation with Reciproc® R25 and after preparation with each file of the complementary systems (MTwo and K3). The morphometric data were analyzed by CTAn software and the statistical analysis was performed using the SPSS software where the following results were observed. The two-dimensional morphometric analysis showed that the area and the perimeter presented a gradual increase for every evaluated millimeter, starting from the first apical millimeter. There was also a gradual increase in area and perimeter with each change of instrument according to the biomechanical within the sets of groups. There was a statistically significant difference in area and perimeter of root canals after the preparation with the instruments #40 taper 04 and taper 02 (P <0.05). Regarding the distance from the apex area, there was statistically difference among all evaluated millimeters (P <0.05). Regarding the perimeter, there was no difference between 1 and 2 mm, and 4 or 5 (P> 0.05), however with a difference between the third millimeter and the others (P <0.05). The three-dimensional morphological analyses of volume, surface area and root canal SMI (Structural Model Index) of the root canal showed a similar behavior among the groups. The specimens subjected to complementation to the instrumentation with instruments of tapers 04 and 02 showed no statistically significant difference after preparation (P> 0.05), with significant difference between the original and prepared canals (P <0.05). When comparing the sets of groups, no analogue group presented a statistically significant difference (P> 0.05). Transport was analyzed by thirds (cervical, middle and apical) and throughout the canal there, without statistically difference (P> 0.05) among the thirds or between groups with complementation with taper 04 (MTwo) and taper 02 (K3) instruments.

Afin de mieux comprendre le comportement mécanique de l’os trabéculaire et d’améliorer la prédiction du risque de fracture, l’objectif de cette thèse est de développer un modèle numérique « bio-fidèle » prenant en compte l’hétérogénéité tissulaire, et de déterminer les contraintes mécaniques au sein des travées osseuses, dans le domaine de déformation élastique. À l’échelle tissulaire, une étude par nanoindentation a permis de dissocier les comportements élastiques et plastiques de l’os en fonction de sa composition (minéral/collagène). Ainsi, le comportement élastique du tissu osseux serait principalement lié à sa quantité de minéral alors que ses propriétés plastiques seraient davantage liées à la phase organique. Une loi reliant le degré de minéralisation de l’os (DMB) au module élastique a été déterminée dans l’os humain. La création d’un modèle numérique reproduisant de manière rigoureuse le comportement élastique de l’os trabéculaire, nécessite la prise en compte de l’hétérogénéité de la quantité de minéral (DMB) et donc son acquisition en 3D. Grâce à une méthode de recalage d’image 2D/3D, les acquisitions de microtomographie ont été comparées aux valeurs obtenues par microradiographie quantitative, méthode de référence de mesure du DMB. Sous certaines conditions, la microtomographie permet une évaluation correcte de l’hétérogénéité minérale. La création et l’analyse d’un modèle numérique par éléments finis de l’os trabéculaire, à partir des images de tomographie, a montré l’importance des paramètres du modèle (taille et formulation des éléments) ainsi que le rôle de l’hétérogénéité minérale sur l’évaluation des contraintes locales appliquées aux travées osseuses. / Finite element modeling has become more and more suitable to estimate the mechanical properties of trabecular bone. Such models tend to be used to evaluate bone fracture risk. The main goal of this study was to create a bio-faithful model of trabecular bone to evaluate elastic stresses fields in trabeculae. In a first part, a nanoindentation study lead to a dissociation of elastic and plastic behavior of bone tissue, depending of its composition (mineral/collagen). At osteon level, bone elastic behavior mainly depends on mineral quantity whereas its plastic behavior mainly depends on collagen maturity. The relation between degree of mineralization of bone (DMB) and elastic modulus have been determined for human bone. The purpose of second part of the study was to evaluate DMB heterogeneity inside a 3D model of trabecular bone. Using 2D/3D registration, we compare the results obtain with high resolution microtomography to those from quantitative microradiography, the goldstandard method used to measure DMB. We prove that it was possible to obtain a good evaluation of mineral heterogeneity in trabecular bone by tomography. The last part of this study, is dedicated to the creation of a finite element model of trabecular bone. After analyzing the influence of finite element modeling parameter on the assessment of mechanical response (size and element formulation), we showed that the integration of mineral heterogeneity at the tissue level lead to strong modifications of stress fields in bone trabeculae. The results of this study prove that bone mineral heterogeneity is an important parameter and should be taken into account when evaluating trabecular bone mechanical properties.