Dans le cadre de la vitrification des déchets nucléaires de haute activité à vie longue, un nouveau procédé a été mis en service à l’usine de La Hague en 2010 : le procédé creuset froid. Dans ce procédé, des gradients thermiques apparaissent au sein du bain de verre. Celui-ci forme une couche solide au contact de la paroi froide, appelée « auto-creuset ». Dans cette zone, le verre est soumis à des températures où il peut potentiellement cristalliser. L’objectif de ce travail était de déterminer la microstructure de cet auto-creuset en précisant les zones de cristallisation. Parallèlement, il s’agissait d’évaluer l’impact du gradient thermique sur la cristallisation des verres considérés. La cristallisation de deux verres d’intérêt nucléaire a donc été étudiée à l’aide d’une méthode basée sur l’analyse d’images MEB en conditions de traitements isotherme et sous gradient thermique. Les analyses en isotherme mettent en évidence la cristallisation de cristaux d’apatite (660°C-900°C) et de powellite (630°C-900°C) et permettent de quantifier cette cristallisation (vitesses de croissance et de nucléation, fraction cristallisée) qui reste très limitée (< 3%). La comparaison des résultats issus de ces deux types d’expérimentations montre que le gradient thermique n’a pas d’impact mesurable sur les cristallisations observées. Afin de compléter les analyses surfaciques de la cristallisation, des mesures par microtomographie in et ex situ ont été réalisées à l’ESRF sur la ligne ID19. Cette étude a permis de suivre la cristallisation d’apatites dans un verre simplifié et de confirmer la fiabilité de la méthode de quantification de la cristallisation basée sur l’analyse d’images 2D. / In the context of the vitrification of high level nuclear waste, a new industrial process has been launched in 2010 at the La Hague factory: The skull melting process. This setup applies thermal gradients to the melt, which leads to the formation of a solid layer of glass: the “self-crucible”. The question would be to know whether these thermal gradients have an impact or not on the crystallization behaviour of the considered glasses in the self crucible. In order to answer that question, the crystallization of two glass compositions of nuclear interest has been investigated with an image analysis based method in isothermal and thermal gradient heat treatments conditions. The isothermals experiments allow for the quantification (growth speed, nucleation, crystallized fraction) of the crystallization of apatites (660°C-900°C) and powellites (630°C- 900°C). The comparison of the results obtained through these two types of experimentations allows us to conclude that there is no impact of the thermal gradient on the crystallization of the studied glass compositions. In order to complete the image analysis study (based on surfaces), in and ex situ microtomography experiments have been performed at ESRF (Grenoble) on the ID10 beamline. This study allowed us to follow the crystallization of apatites in a simplified glass and to confirm the reliability of the image analysis method based on the analysis of surfaces.

Orientador: Juliane Maria Guerreiro Tanomaru / Resumo: Os instrumentos de níquel-titânio usados durante o preparo dos canais radiculares podem sofrer diferentes processos de tratamento na liga durante a fabricação. Sistemas de instrumentação mecanizada apresentam formatos individuais dos instrumentos, sendo sugeridas diversas cinemáticas de atuação durante a ação de corte da dentina. Os sistemas de único instrumento usados em cinemática reciprocante e novos instrumentos com tratamento térmico das ligas devem ser estudados quanto ao efeito sobre o preparo do canal e dentina radicular. A anatomia do canal, as técnicas obturadoras e o emprego de diferentes materiais podem influenciar na qualidade da obturação. O objetivo do estudo foi avaliar o preparo de canais achatados de incisivos inferiores e canais mesiais de molares inferiores com instrumento rotatório e/ou reciprocante, bem como a qualidade da obturação usando diferentes técnicas ou cimento de silicato de cálcio. Noventa incisivos inferiores apresentando canais achatados foram preparados com sistema Mtwo em rotação contínua (Mtwo rot) até 40/.06; Mtwo 40/.06 instrumento único em cinemática reciprocante horária (Mtwo rec) e Reciproc (R40) (n=30). Os dentes foram escaneados por microtomografia computadorizada (Micro-CT) antes e após o preparo. Os dados foram expressos em porcentagem do aumento de volume do canal (%V), redução da espessura de dentina (%DTR), área de superfície não instrumentada (%S) e debris remanescente (%D). O tempo necessário para o preparo foi anotado. Cana... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The nickel-titanium instruments used during the preparation of root canals can present different treatment processes in alloy during manufacturing. Mechanized instrumentation systems present instruments with individual formats, being suggested various kinematics during the action on the dentin. Single instrument systems used in reciprocating kinematics and the new instruments with thermal treatment of alloys should be studied as to the effect on the preparation of the root canal and dentin. The anatomy of the root canal, the filling techniques and the use of different materials can influence in the quality of filling. The objective of this study was to evaluate the flattened root canal preparation of mandibular incisors and mesial root canals mandibular molars using rotatory and/or reciprocating instruments, as well the quality of root canal obturation using different techniques or calcium silicate sealer. Ninety mandibular incisors presenting flattened canals were prepared using Mtwo system in continuous rotation (Mtwo rot) up to 40/.06; Mtwo 40/.06 single instrument in reciprocating motion (Mtwo rec) and Reciproc (R40) (n = 30). The teeth were scanned by computed microtomography (Micro-CT) before and after the preparation. Data were expressed as a percentage of the increase in volume of root canal (% V), reduction of the thickness dentin (% DTR), uninstrumented surface area (% S) and remaining debris (% D). The time required for the preparation was noted. Mesial root canals... (Complete abstract click electronic access below) / Doutor

A técnica de levantamento de seio maxilar (LSM) visa aumentar a altura óssea junto à superfície sinusal de maxila posterior atrófica utilizando diferentes materiais de preenchimento, para possibilitar a instalação de implantes dentários. Esses materiais de preenchimento podem variar quanto à origem e às propriedades físicoquímicas, resultando em diferentes respostas biológicas. O objetivo do atual trabalho foi avaliar a eficiência do Gen-Ox®inorg e GenPhos XP® na técnica de elevação do seio maxilar em comparação ao Bio-Oss®. Em 24 coelhos foi realizado o levantamento bilateral dos seios maxilares (SMs) utilizando 200 mm3 de material de preenchimento por seio, conforme os grupos experimentais Bio-Oss (6SMs/período), Gen-Ox (5SMs/período) e GenPhos (5SMs/período), e a janela óssea de acesso foi recoberta com uma membrana reabsorvível. Os animais de cada grupo foram eutanasiados aos 15, 30 e 60 dias e a região dos SMs foi coletada e fixada em formalina a 10% tamponada. As peças foram submetidas à análise microtomográfica para determinação do volume total do SM elevado e em seguida ao processamento histológico, sendo cortes coronais dos SMs obtidos e avaliados morfometricamente pelo método de volumetria de pontos. Todos os três materiais apresentaram excelente biocompatibilidade e promoveram a manutenção do volume do seio preenchido ao longo do tempo, sendo em média de 214,1 mm3. Em todos os grupos a formação óssea ocorreu em íntimo contato com as partículas de material. Ao término de 60 dias, o tecido ósseo formado mostrava-se maduro e preenchia parcialmente os espaços entre as partículas. A forma e tamanho das partículas de Gen-Ox gerou maior espaço entre as partículas que pode ter levado a formação de maior volume de tecido ósseo e de tecido conjuntivo (53,0 ± 10,1 mm3 e 74,1 ± 21,5 mm3) comparado ao Bio-Oss (43,7 ± 11,6 mm3 e 61,2 ± 23,3 mm3) e GenPhos (47,5 ± 10,4 mm3 e 58,5 ± 25,7 mm3). Baseado na estabilidade do volume sinusal elevado, na capacidade osteocondutora e na formação e maturidade óssea ao longo do tempo promovidos pelo Gen-Ox®inorg e GenPhos®, comparável ao do Bio-Oss®, conclui-se que esses dois biomateriais significam uma alternativa segura na técnica de LSM. / Maxillary sinus augmentation (MSA) for implant placement using bone graft or bone substitutes is a common procedure to increase the bone volume in the atrophic posterior part of the maxilla. Various bone substitutes have been used in sinus floor elevation procedures. Nonetheless, the biological performance of bone substitutes may vary according to origin, physical and chemical properties. The goal of this study was to evaluate the efficiency of both Gen-Ox®inorg and GenPhos XP® in maxillary sinus augmentation technique compared to Bio-Oss®. In 24 rabbits, it was conducted a bilateral lifting of the maxillary sinuses (MSs) using 200 mm3 of filling material for sinus in accordance with the experimental groups Bio-Oss (6SMs/period), Gen-Ox (5MSs/period) and GenPhos (5MSs/period). The sinus access window was covered with a resorbable membrane. The animals of each group were euthanized at 15, 30 and 60 days and the MSs were collected and fixed in 10% buffered formalin. The samples were submitted to microtomographic analysis to calculate the MS augmentation volume. Histological coronal sections of MS augmentation were used for morphological analysis and determination of volume density of each structure by point counting volumetry method. All three materials had excellent biocompatibility and promoted maintenance of the MS augmentation volume over time, averaging 214.1 mm3. In all groups the bone formation occurred in close contact with the material particles. At the end of 60 days, the bone tissue formed was mature and it partially filled the spaces between the particles. The shape and size of Gen-Ox particles generated greater space between the particles that may have led to a higher formation of bone volume and connective tissue (53.0 ± 10.1 mm3 and 74.1 ± 21.5 mm3) than Bio-Oss (43.7 ± 11.6 mm3 and 61.2 ± 23.3 mm3) and GenPhos (47.5 ± 10.4 mm3 and 58.5 ± 25.7 mm3). Based on the stability of the MS volume, the osteoconductive capacity and the bone formation and maturation over time promoted by Gen-Ox®inorg and GenPhos®, and comparable to Bio-Oss®, it is concluded that these two biomaterials may be a safe alternative in MSA technique.

O objetivo desse estudo foi avaliar a adaptação interna e marginal de coroas de dissilicato de lítio obtida por duas técnicas disponíveis pelo sistema CAD/CAM, o escaneamento direto e indireto. As análises foram realizadas por meio do microtomógrafo computadorizado (&microCT), microscópio confocal a laser (CL) e técnica da replica (TR), em dois momentos: antes e após a cristalização do material. O dente 14 de manequim foi preparado e duplicado em silicone, obtendo 20 réplicas em resina de poliuretano. Para a formação do Grupo 1 (IND/n=08), o manequim foi moldado com moldeira de estoque e silicone de adição com técnica de moldagem simultânea e modelagem com gesso pedra tipo III e IV, totalizando oito modelos em gesso. Os modelos foram escaneados com escâner indireto. Foram fresadas oito coroas de dissilicato de lítio. Para formação do Grupo 2 (DIR/n=08), o manequim foi escaneado com escâner direto. Oito imagens foram obtidas e enviadas ao laboratório pelo programa do sistema. Da mesma forma, foram fresadas oito coroas de dissilicato de lítio. As leituras da adaptação marginal das coroas foram realizadas com as mesmas adaptadas sobre a respectiva réplica em poliuretano, no &microCT, CL, e TR. As leituras da adaptação interna foram realizadas no &microCT e TR. As análises foram realizadas antes e após a cristalização das coroas. Os dados que apresentaram distribuição normal foram analisados por ANOVA dois fatores e os dados que não apresentaram distribuição normal foram analisados por teste U de Mann-Whitey para comparação entre os Grupos e pelo teste de Wilcoxon para comparação antes e após a cristalização. Em relação à adaptação axial, foi verificada diferença significante apenas para os Tempos (p=0,017), com menores valores após a cristalização. Para a adaptação interna não foi observada diferença entre os Grupos (p>0,05) ou Tempos estudados (p>0,05). Para a adaptação marginal vertical houve diferença para o Grupo IND, com maiores valores após a cristalização independente da metodologia de análise (&microCT - p=0,001; confocal - p=0,038). Já a medida marginal horizontal apresentou resultados divergentes de acordo com a metodologia utilizada. No &microCT, IND foi maior que DIR (p=0,003) e antes maior que após a cristalização (p<0,001). No confocal, IND menor que DIR após a cristalização (p=0,05), e para DIR, antes menor que após a cristalização (p=0,005). No volume total e volume marginal do espaço para cimentação houve diferença significante apenas para o DIR, com maiores valores após a cristalização (volume total - p=0,025; volume marginal - p=0,002). Pelos resultados obtidos pode-se concluir que há contração do material após a cristalização, resultando em maior desadaptação comprovado pelo aumento do volume total do espaço de cimentação em consequência da dificuldade de assentamento da coroa de dissilicato de lítio. / The objective of this study was to evaluate the internal and marginal adaptation of lithium desilicated crowns obtained by two alternative techniques to the CAD / CAM system, direct and indirect scanning. The analyzes were carried out by computerized microtomograph, laser confocal microscope and replica technique, in two moments: before and after the crystallization of the material. The manikin tooth 14 was prepared for total crown. Then it was duplicated, in silicone, and there were obtained 16 replicas in polyurethane resin. Two groups were formed from the impression of the manikin through the direct and indirect scanning, For the Group 1 (IND/n = 08), the manikin was molded with stock tray, with addition silicone, by the simultaneous molding technique and modeling performed with gypsum stone type III and IV, totaling eight molds and plaster models. The models were sent to the laboratory for scanning on the scanner indirect. Dissilicate crowns were made of lithium milled. For the Group 2 (DIR/n = 08), the dummy was scanned by scanner directly. The eight images obtained were sent directly to the laboratory by the system program. Likewise, milled lithium dissilicate crowns were made. The marginal adaptation of the crowns was performed with the same ones on the respective polyurethane tooth, in the computerized microtomograph (&microCT), confocal laser microscope (CL) and through the replica technique (TR). Internal adaptation readings were performed using a &microCT and TR. The analyses were made before and after the crystallization of the crowns. The data showed normal distribution were analyzed by two factors ANOVA and the data did not show normal distribution were analyzed for U Mann-Whitney test for comparison among groups and by the Wilcoxon test for comparison before and after the crystallization . In relation to the axial adaptation, significant difference was verified only for Times (p = 0.017), with lower values after crystallization. For the internal adaptation was not observed difference between groups (p > 0.05) or Times studied (p > 0.05). For the vertical marginal adaptation difference to the IND group, with higher values after the crystallization analysis methodology-independent (&microCT p = 0.001;-p = 0.038 confocal). Already the measure presented divergent results horizontal marginal according to the methodology used. In &microCT, IND was greater than DIR (p = 0.003) and greater than after the crystallization (p < 0.001). In confocal IND less than DIR after the crystallization (p = 0.05), and DIR, before less than after the crystallization (p = 0.005). In total volume and marginal volume of space for cementation significant difference only to the DIR, with higher values after the crystallization (total volume - p = 0.025; marginal volume - p = 0.002). The results obtained can be concluded that there is contraction of the material after the crystallization, resulting in higher leakage evidenced by the increase of the total volume of the cementing space as a result of the settling difficulty the dissilicate Crown.

Avaliação da \"qualidade\" da microarquitetura óssea contribui na prevenção e risco de fraturas associado a osteoporose. Amostras de ossos trabeculares de corpos vertebrais da região T12, L1 e L4 de 30 de indivíduos (cadáveres humanos), classificados pela técnica de ultrassonometria de calcâneo como normais, osteopênicos e osteoporóticos foram utilizadas. Os parâmetros histomorfométricos, físicos e mecânicos da microarquitetura analisados pela técnica de microtomografia de raios-X, ensaios mecânicos de compressão axial e nanoindentação. Baseado nestes parâmetros, constantes elásticas efetivas globais foram obtidas pela técnica homogeneização assintótica para estrutura tipo-placa. Teste ANOVA apresentou diferenças, muito e extremamente significativas para densidade linear estrutural (p = 0,017), grau de anisotropia (p = 0,042), auto valor (p = 0,045), número de Euler (p = 0,016), idade (p = 0,009), separação trabecular (p = 0,009), densidade de conectividade (p = 0,006), módulo de elasticidade (p = 0,001), tensão máxima no limite de resistência a fratura (0,001), índice de qualidade óssea do calcâneo (p = 0,0001), fração de volume ósseo (p = 0,0001), espessura trabecular (p = 0,0002), dimensão fractal (p = 0,0002), momento de inércia polar médio (p = 0,00005), excentricidade (p = 0,0002), fração de porosidade (p = 0,0001) e densidade mineral óssea aparente (p = 0,00005) entre os grupos. O teste de Spearman identificou correlação moderada, alta e muito alta dos valores da tensão máxima no limite de resistência a fratura com os parâmetros de idade (r = -0,684), fração de volume ósseo (r = 0,762), fator de forma trabecular (r = -0,754), espessura trabecular (r = 0,675), densidade linear trabecular (r = 0,622), autos valores (r = -0,615), dimensão fractal (r = 0,855), momento de inércia polar médio (r = 0,816), excentricidade (r = -0,569) e fração de porosidade (r = -0,762). Estes parâmetros são indicadores da qualidade da microarquitetura óssea trabecular e risco de fratura associado a osteoporose. / Evaluation of the \"quality\" of bone microarchitecture can contribute to the prevention and risk of fractures associated with osteoporosis. Samples of trabecular bone from the vertebral regions T12, L1 and L4 from the bodies of 30 individuals (human cadavers), classified by ultrasonometry technique calcaneus as normal, osteopenic and osteoporotic were used. The histomorphometric, physical and mechanical parameters of the microarchitecture were analyzed by X-ray microtomography technique, mechanical tests of axial compression and nanoindentation. Based on these parameters, globally effective elastic constants were obtained by asymptotic homogenization technique for type-plate structure. ANOVA test showed differences that were very and extremely significant for the following: structural linear density (p = 0.017) anisotropy (p = 0.042), auto value (p = 0.045), Euler number (p = 0.016), age (p = 0.009), trabecular separation (p = 0.009), connectivity density (p = 0.006), elastic modulus (p = 0.001), maximum stress fracture strength limit (0.001), bone quality score of the calcaneus (p = 0.0001), bone volume fraction (p = 0.0001), trabecular thickness (p = 0.0002), fractal dimension (p = 0.0002), mean polar moment of inertia (p = 0.00005), eccentricity (p = 0.0002), porosity fraction (p = 0.0001) and apparent bone mineral density (p = 0.00005) between groups. The Spearman test identified moderate correlation, high and very high values of maximum stress fracture resistance limit for the following parameters: age (r = -0.684), bone volume fraction (r = 0.762), trabecular bone pattern factor (r = -0.754), trabecular thickness (r = 0.675), trabecular linear density (r = 0.622), auto value (r = -0.615), fractal dimension (r = 0.855), mean polar moment of inertia (r = 0.816), eccentricity (r = -0.569) and porosity fraction (r = -0.762). These parameters are quality indicators of the microarchitecture of trabecular bone and fracture risk associated with osteoporosis.

Universidade de São Paulo, Faculdade de Medicina; 2015. Introdução: Diante de uma rotura traumática do manguito rotador, não há evidência direta que comprove que os reparos realizados precocemente são mais eficazes que aqueles realizados tardiamente. Para abordar essa questão, ensaios biomecânicos e de morfometria óssea foram realizados após roturas extensas do manguito rotador realizadas precocemente (lesões agudas) e tardiamente (lesões crônicas), mediante a utilização de um modelo experimental em ratos. Método: 30 ratos adultos da raça Wistar foram aleatoriamente divididos em três grupos (I, II e III) e submetidos à secção completa dos tendões do supraespinal e infraespinal nos ombros esquerdos. Após oito semanas, nos animais dos grupos I e II, os tendões rotos pertencentes aos ombros esquerdos foram cirurgicamente reparados, e os tendões equivalentes nos ombros direitos foram seccionados e imediatamente reparados. Quatro semanas após os reparos (para os ratos do grupo II) ou oito semanas após os reparos (para os ratos do grupo I), os animais foram submetidos à eutanásia. Os ratos do grupo III foram submetidos à eutanásia oito semanas após a cirurgia de secção tendínea sem que houvesse ocorrido o reparo dos tendões rotos. Os ombros direitos dos animais do grupo III permaneceram intactos e serviram como controles. Após a eutanásia, todos os ratos tiveram seus ombros dissecados e os espécimes foram encaminhados para a realização de testes biomecânicos e de microtomografia computadorizada. Resultados: Para todos os parâmetros biomecânicos analisados, foram encontradas interações significantes referentes aos fatores tempo de cicatrização e reparo, considerando os reparos precoces e tardios. Com relação ao tendão supraespinal para o período de oito semanas de cicatrização, a força máxima até a falha foi significantemente maior nos reparos precoces em comparação aos reparos tardios (31,81 ± 3,86N vs 19,36 ± 6,14N; p < 0,001), bem como a rigidez (17,22 ± 4,35N/mm vs 10,85 ± 4,25N/mm; p=0,034), a tensão máxima até a falha (4,49 ± 2,02N/mm2 vs 1,97 ± 0,61N/mm2; p < 0,001) e o módulo de elasticidade (13,72 ± 5,29N/mm2 vs 6,47 ± 2,42 N/mm2; p=0,033). Com relação ao tendão infraespinal com oito semanas de cicatrização, a força máxima até a falha foi significantemente maior nos reparos precoces em comparação aos reparos tardios (21,26 ± 3,94N vs 12,74 ± 2,87N; p=0,005), assim como a rigidez (12,86 ± 2,65N/mm vs 7,21 ± 3,30N/mm; p=0,014). O grupo com reparo tardio com oito semanas de cicatrização obteve resultados nos testes biomecânicos semelhantes aqueles obtidos nos testes do grupo com lesão sem reparo com oito semanas de cicatrização. A avaliação microtomográfica não apresentou diferenças significantes na microarquitetura óssea entre os reparos realizados precocemente e tardiamente. Conclusões: Os resultados desse estudo demonstram que as roturas extensas do manguito rotador reparadas precocemente produzem um tecido cicatricial na junção ósteo-tendínea com melhores propriedades biomecânicas que as roturas reparadas tardiamente. Porém, ao analisar a morfometria óssea da porção proximal do úmero, verificou-se que os efeitos são equivalentes, tanto para os reparos realizados tardiamente quanto para os reparos realizados precocemente / Introduction: In the event of a traumatic rotator cuff tear, there is no direct evidence that supports early over late surgical repair. To address this knowledge gap, biomechanical and bone morphometry outcomes were assessed following early (acute) and late (chronic) massive rotator cuff tear repairs in an experimental rat model. Methods: 30 adult Wistar rats were randomly divided into three groups (I, II and III), then subjected to combined supraspinatus and infraspinatus tendon tears of the left shoulder. Eight weeks following the injury, animals from groups I and II had the tendons of the injured shoulder surgically repaired. In addition, these animals were subjected to the same injury on the contralateral shoulder, which was immediately repaired. The rats were euthanized four weeks (group II) or eight weeks (group I) following the repairs. Group III was euthanized eight weeks following the injury, without surgical repair of the left shoulder, and the intact right shoulders of this group were used as controls. Tissues from all groups were harvested and subjected to biomechanical testing and bone morphometry analysis. Results: In all biomechanical parameters analyzed, a significant interaction was observed between healing and repair timing. For the supraspinatus tendon with eight weeks healing time, biomechanical properties were significant increased in the early repair group compared to the late repair group, including maximum load to failure (31,81 ± 3,86N vs 19,36 ± 6,14N; p < 0,001), stiffness (17,22 ± 4,35N/mm vs 10,85 ± 4,25N/mm; p=0,034), maximum stress to failure (4,49 ± 2,02N/mm2 vs 1,97 ± 0,61N/mm2; p < 0,001) and modulus of elasticity (13,72 ± 5,29N/mm2 vs 6,47 ± 2,42 N/mm2; p=0,033). For the infraspinatus tendon with eight weeks healing time, biomechanical properties were also significantly increased in the early repair group, including maximum load to failure (21,26 ± 3,94N vs 12,74 ± 2,87N; p=0,005) and stiffness (12,86 ± 2,65N/mm vs 7,21 ± 3,30N/mm; p=0,014). There were no significant differences between the late repair with eight weeks of healing time and the group without surgical repair for supraspinatus and infraspinatus tendons. Concerning bone morphometry of the humeral head, no significant differences were observed when comparing early and late repair groups. Conclusions: The results from this study indicate that early surgical repair of a massive rotator cuff tear leads to increased biomechanical properties of the tissue after healing. However, proximal humerus bone morphometry was unaffected by surgical repair timing

Orientador: Rafael Nobrega Stipp / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-25T14:55:16Z (GMT). No. of bitstreams: 1 Rodrigues_ItaloSartoCarvalho_D.pdf: 947131 bytes, checksum: 718f334861a919e4b10e20f1d03bdfd3 (MD5) Previous issue date: 2014 / Resumo: O biofilme é uma população biológica com um elevado grau de organização, onde os microrganismos presentes formam uma comunidade estruturada, coordenada e funcional. O estudo do comportamento dos biofilmes é fundamental para melhorar as formas de controle, especialmente durante infecções, tais como as doenças periodontais. No primeiro capítulo, foram avaliados os efeitos da aplicação tópica e frequente do digluconato de clorexidina (CLX) em diferentes concentrações na periodontite induzida por ligadura nos primeiros molares de ratos. As ligaduras receberam 10 µl de soluções de CLX à 0,2%, 2%, 10%, 20% ou diluente, de quatro em quatro dias, em um total de quatro aplicações. Após eutanásia, a quantidade de células bacterianas no biofilme formado sobre a ligadura foi estimada por cultura e por PCR quantitativo. A reabsorção óssea foi mensurada em altura e área por fotografia digital e em volume por microtomógrafo. Depois de quatro dias a partir da última aplicação da CLX, as reduções bacterianas mantidas pelos tratamentos com CLX atingiram até 10-6. O grupo que recebeu CLX a 20% teve, em média, logs bacterianos 3,3× menor (p<0.01, Kruskal-Wallis). Não houve diferença estatística entre os grupos em relação à reabsorção óssea por ambos os métodos testados (p>0.05, Kruskal-Wallis), embora 55% dos sítios apresentaram menor reabsorção óssea. No segundo capítulo, foi avaliada a influência de diversas substâncias na formação de biofilme por Prevotella intermedia. Os biofilmes foram formados em placas de 48 poços contendo tratamento de superfície prévio com DNA purificado, hemina, CaCO3, Ca(OH)2, CaCl2, soro, albumina, dextrana, metionina, glicose, glutamina, KCl, complexo vitamínico, cistina ou mucina. O biofilme formado foi corado e quantificado por espectrofotometria. A arquitetura do biofilme foi visualizada por microscopia confocal de fluorescência por varredura laser. O tratamento da superfície com CaCl2 a 1 mg/cm2 permitiu a formação do biofilme em quantidade de 0,3 OD490nm (p<0.01, ANOVA Dunnet), sendo esse valor 10× superior quando a superfície foi tratada com 2,5 mg/cm2 (p<0.01, ANOVA Dunnet). As demais substâncias tiveram pouco ou nenhum impacto sobre a formação do biofilme. A visualização por microscopia confocal revelou uma comunidade estruturada e com vitalidade em toda sua espessura. Conclusões: os dados indicam que a CLX concentrada diminui a carga bacteriana na região da periodontite induzida, que reflete em menor reabsorção óssea apenas em parte das amostras. O pré-revestimento da superfície de crescimento com cálcio promove a formação de biofilme por P. intermedia / Abstract: Biofilms are biological communities with a high degree of organization, in which micro-organisms form structured, coordinated and functional communities. These biological communities are embedded in a self-created extracellular matrix. Biofilm is also associated with a high level of antimicrobial tolerance of the associated organisms. Understanding biofilm behavior is crucial to develop ways for its control during infections, such as periodontal disease. In the first chapter, topical and frequent application of various concentrations of chlorhexidine digluconate (CLX) where evaluated. Periodontitis were induced by ligature on first molars. Then, ligatures were treated with 10 µl of chlorhexidine solutions at 0.2%, 2%, 10%, 20% or diluent, every four days in a total of four applications periods. After euthanasia, bacterial loads on ligatures were estimated by both culture and qPCR. Bone resorption height and area were measured by digital photography and its volume by microtomography. Treated sites had bacterial reductions up to 10-6 cells. Treatment with 20% CLX showed mean of 3.3× lower bacterial levels (p<0.01, Kruskal-Wallis). There was no statistical difference between groups regarding bone resorption (p>0.05, Kruskal-Wallis), although 55% of the treated sites had some lower bone resorption. In the second chapter, substances that may enhance biofilm formation by Prevotella intermedia were investigated. Wells of 48-well plates were coated with DNA, hemin, CaCO3, Ca(OH)2, CaCl2, serum, albumin, dextran, methionine, glucose, glutamine, KCl, vitamin complex, cystine or mucin. Biofilms were grown for 24 h, washed, stained and quantified by spectrophotometry. Biofilm architecture and its viability were visualized by Confocal Laser Scanning Microscopy. Surfaces treated with 1 mg/cm2 of CaCl2 enhanced biofilm amount by 0.3 OD490nm (p<0.01, ANOVA Dunnet), while 2.5 mg/cm2 yielded 10-fold more biofilm mass (p<0.01, ANOVA Dunnet). Other substances had modest or no impact in biofilm mass. Confocal microscopy images showed structured and alive biofilms with no dead areas. Conclusions: concentrated CLX reduces bacterial load, which reflects in lower bone resorption in few sites. Surfaces pre-coated with calcium chloride enhance P. intermedia biofilm formation / Doutorado / Microbiologia e Imunologia / Doutor em Biologia Buco-Dental

La thèse a pour but de caractériser les propriétés mécaniques de matériaux à base de fibres de bois en relation avec les propriétés intrinsèques des fibres et leur arrangement spatial complexe. Ce type de matériau, dont les caractéristiques dépendent de sa configuration, est hétérogène à différentes échelles : à l’échelle microscopique de la fibre, à l’échelle mésoscopique du réseau des fibres et à l’échelle macroscopique du matériau. Pour observer ces hétérogénéités, différents moyens expérimentaux de caractérisation sont utilisés, notamment la microtomographie aux rayons X et la corrélation d’images volumiques. Ces deux techniques permettent à la fois de visualiser et numériser la position spatiale des différentes fibres du matériau à l’échelle microscopique dans le volume, et d’obtenir le champ tridimensionnel de déformation à cœur. Comme résultats, le matériau étudié montre un comportement non-linéaire avec une déformation résiduelle et un effet d’hystérésis en charge/décharge, qui suit le modèle de Van-Wyk. A l’échelle microscopique, le champ de déformation 3D apparait fortement hétérogène et est intimement lié aux porosités locales. / This thesis aims at characterizing the mechanical properties of wood-based fibrous material in relation with the intrinsic properties of the fiber as well as the complex architecture of random fibrous assembly. This material, whose characteristics strongly depend on its configuration, is heterogeneous at different scales: microscopic scale of individual fibers, mesoscopic scale of fiber assembly and macroscopic scale of sample. In order to observe these heterogeneities, different experimental characterization methods are employed, especially X-ray microtomography and Digital Volume Correlation. These both techniques allow us to visualize and digitize the spatial position of different phases of material at microscopic scale as well as the full 3D strain field inside the material. The obtained results are following: the material shows a non-linear mechanical behavior with hysteresis and residual deformation during cyclic compression tests, which respects Van Wyk's model. At microscopic scale, the 3D strain field is strongly heterogeneous and deeply related to local porosities.

En conditions saines, le tissu osseux est constamment remodelé pour s’adapter aux différentes contraintes mécaniques, réparer les microfissures et maintenir l’homéostasie minérale. Ce remodelage est effectué par les ostéoblastes et les ostéoclastes, responsables de la formation et de la résorption du tissu osseux. Leurs activités sont orchestrées par les ostéocytes, cellules osseuses les plus abondantes, via la mechanotransduction. Dans cette thèse, nous avons utilisé la microtomographie par rayonnement synchrotron afin d’étudier la morphologie du réseau lacuno-canaliculaire (LCN), ainsi que la distribution 3D de la densité massique des tissus osseux minéralisés, sur des sujets sains ou atteints d’ostéonécrose de la mâchoire suite à un traitement par bisphosphonates (BP). Les BP sont utilisés pour le traitement de l’ostéoporose et des métastases osseuses, limitant la résorption osseuse par les ostéoclastes. Nous avons supposé que les patients ainsi traités présentaient un volume de lacunes ostéocytaires plus grand, dû à la résorption du tissu péri-lacunaire par ostéolyse ostéocytaire. Le sujet affecté par un manque de minéraux induit par la réduction du remodelage ostéoclastique, maintiendrait ainsi son homéostasie minérale. Cette hypothèse n’a pas été confirmée, mais nous avons toutefois remarqué que les lacunes larges étaient plus abondantes dans la mâchoire que dans le tibia et le fémur. Cela s’expliquerait par l’accumulation préférentielle des BP dans la mâchoire, au taux de remodelage élevé. De plus, si ces BP sont déposés dans les lacunes ostéocytaires pendant le processus de minéralisation, des concentrations toxiques pourraient être atteintes en cas d’infection, conduisant alors à une diminution du pH, et à la dissolution des minéraux. Nous avons également utilisé la nanotomographie par rayonnement synchrotron avec reconstruction de phase pour analyser la morphologie du LCN et les propriétés du tissu avoisinant, sur mâchoires de sujets sains et traités par BP. Nous supposons qu’une minéralisation secondaire a lieu via la diffusion des minéraux à travers l’interface fluide-matrice, à la surface des lacunaire et des canalicules. Cela devrait conduire à une variation de la densité massique en fonction de la distance par rapport au bord des porosités, que nous avons effectivement observé. Ainsi, l’échange minéral entre le fluide extracellulaire et la matrice minéralisée s’effectue à la frontière des lacunes et des canalicules. Nos données suggèrent que la capacité d’échange de minéraux entre le réseau poreux et la matrice osseuse augmenterait d’un ordre de grandeur si la surface canaliculaire était prise en compte. Le modèle de diffusion résultant de nos études devrait contribuer à une meilleure compréhension puis optimisation du traitement. Toutefois, des études complémentaires sur les modifications des propriétés du tissu pendant la minéralisation secondaire et les fluctuations des concentrations du minéral dans le sang sont nécessaires. / Under healthy conditions, human bone undergoes permanent remodeling to adjust to mechanical demands, to repair micro-cracks and to maintain mineral homeostasis. This process of remodeling is performed by osteoblasts and osteoclasts: bone-forming and bone-resorbing cells. The activity of osteoclasts and osteoblasts is triggered by osteocytes, the most frequently occurring type of bone cell, via mechanosensation processes. Bisphosphonates (BP) prescribed during treatment for osteoporosis or bone metastasis inhibit osteoclast activity and thus decrease the bone turnover. In this work, the distribution and morphology of osteocyte lacunae of human cortical jaw bone was investigated in 3D, and a comparison between healthy and BP-treated donors was performed using synchrotron radiation (SR) µCT. In a second approach, we used SR nano-CT with phase contrast to investigate the morphology of the canalicular network and the bone tissue properties in the vicinity of the lacuna-canalicular network of human jaw bone, originating from both healthy subjects and patients treated with BPs. We hypothesized that secondary mineralization takes place via a diffusion process through the fluid-matrix interface at both the lacunar and the canalicular surfaces. This should result in mass density gradients with respect to the distance to the pore boundary. Such mass density gradients were indeed observed at both lacunar and canalicular interfaces. We concluded that mineral exchange between extracellular fluid and mineralized matrix occurs at all bone surfaces, including the canaliculi. Our data suggested that the capacity of the pore network to exchange mineral with the bone matrix would increase by one order of magnitude if the canalicular surface is taken into account. However, more studies should be performed, targeting not only the changes of tissue properties during secondary mineralization, but also during fluctuations of mineral concentration in periods of high mineral demand.

L’utilisation des matériaux à faibles impacts environnementaux devient essentielle dans le secteur du bâtiment à cause de sa forte consommation d’énergie et de ressources naturelles. Cette thèse porte sur les isolants bio-sourcés et spécialement les laines de chanvres possédant des propriétés thermiques et hydriques intéressantes. La laine de chanvre, étant composée essentiellement de fibres végétales, constitue un matériau fibreux anisotrope et fortement poreux, et possède à l’échelle microscopique une structure complexe et aléatoire. D’où l’intérêt de décrire précisément la morphologie de ce type de laine et de caractériser sa structure par analyse d’images tomographiques à rayons X et des images MEB. Puis nous avons mis en place un modèle macroscopique couplé de transfert de chaleur et de masse, permettant de comprendre le comportement thermohydrique de ces laines en utilisant la méthode de changement d’échelle par prise de moyenne. Pour prendre en compte la complexité géométrique de la microstructure nous avons eu recours à un double changement d’échelle. / The use of low environmental impact materials becomes essential in the construction industry due to its high consumption of energy and natural resources. In this thesis it was focused on the bio-based and especially wool hemp insulation with interesting thermal and water properties. Hemp wool, being composed substantially of plant fibers, is an anisotropic, fibrous and highly porous material. At the microscopic level it possesses a complex and random structure, hence the interest of an accurate description to the morphology of this type of wool and to characterize its structure analysis by X-ray tomographic images and SEM images. Then a macroscopic model of coupled heat transfer and mass transport is set up to understand the behavior of these wools using the scaling method average gain. To take into account the geometric complexity of the microstructure a double change of scale was used.