Different tracing techniques of the subperiosteal and endosteal contours (manual, automatic, semi-automatic) or their combinations taken along femoral length in adult individuals can produce different values of cross-sectional geometric (CSG) parameters. Various tracing techniques are widely used in CSG studies of non-adult individuals as well, however, the accuracy of CSG parameters estimated along femoral diaphysis is not yet known for non-adult individuals. In this study, we investigate whether the manual tracing of the subperiosteal and endosteal contours taken at 80% of the femoral diaphyseal length in non-adult individuals can be replaced by another type of tracing in relation to CSG parameters estimation. We examine the effect of anatomical localization on accuracy of the CSG parameters estimated in non-adult individuals femora. We digitized the subperiosteal and endosteal contours in the micro-CT scans from femoral diaphyseal cross-sections in Early Medieval sample of non-adult individuals (N = 46). The digitization and computation of CSG parameters were made in Fiji software with EPJMacro implementation. The assessment of estimates' accuracy was expressed by percentage prediction error (%PE) and limits of agreement. Five percent of CSG parameter obtained from manually traced contours was...

<p></p><p>Additive Manufacturing (AM) allows for the creation of elements with novel forms and functions. Utilizing AM in development of components of civil infrastructure allows for achieving more advanced, innovative, and unique performance characteristics. The research presented in this dissertation is focused on development of a better understanding of the fabrication challenges and opportunities in AM of cement-based materials. Specifically, challenges related to printability and opportunities offered by 3D-printing technology, including ability to fabricate intricate structures and generate unique and enhanced mechanical responses have been explored. Three aspects related to 3D-printing of cement-based materials were investigated. These aspects include: fresh stability of 3D-printed elements in relation to materials rheological properties, microstructural characteristics of the interfaces induced during the 3D-printing process, and the mechanical response of 3D-printed elements with bio-inspired design of the materials’ architecture. This research aims to contribute to development of new pathways to obtain stability in freshly 3D-printed elements by determining the rheological properties of material that control the ability to fabricate elements in a layer-by-layer manner, followed by the understanding of the microstructural features of the 3D-printed hardened cement paste elements including the interfaces and the pore network. This research also introduces a new approach to enhance the mechanical response of the 3D-printed elements by controlling the spatial arrangement of individual filaments (i.e., materials’ architecture) and by harnessing the weak interfaces that are induced by the 3D-printing process. </p><br><p></p>

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På CBH (Skolan för kemi, bioteknologi och hälsa) har en mikro-CT utvecklats, men med förbättringspotential gällande användbarheten. Målet med kandidatexamensarbetet var att förbättra mjukvaran genom att automatisera tre olika aspekter av manuell datahantering: Dels att placera filerna i en mapp med namn kopplat till valda bildtagningsinställningar. Dels att kopiera data via SCP mellan två datorer kopplade till mikro-CT:n. Samt att radera kopierade data från disken som preliminärt sparar filerna. För att möjliggöra en automatisk dataöverföring implementerades ett SSH-nyckelpar med publik nyckelautentisering mellan de två datorerna. Till den befintliga mjukvaran tillades ett skript samt en klass med handhavande över de tre automatiseringsaspekterna. Genom användargränssnittet hämtar klassen inledningsvis information om bildtagningsinställningarna till mappnamnet och när bildtagningen är klar anropar programkoden skriptfilen som utför SCP-kopieringen. Därefter kontrolleras att inga data gått förlorade under överföringen, varefter en radering av de kopierade filerna utförs på den ursprungliga disken. Den nya klassen förbättrar mikro-CT:ns användarvänlighet och underlättar hanteringen av data efter en bildtagning. / At CBH (The School of Engineering Sciences in Chemistry, Biotechnology and Health) a micro-CT has been developed, but the system has potential improvement regarding the usability. The purpose of this bachelor’s thesis was to improve the software by automatizing three aspects of manual data handling: Firstly to place the data in a folder with a name related to the obtained acquisition settings. Secondly to transfer files through SCP between the two computers connected to the micro-CT. Lastly to delete the copied data from the disk that initially saves the files. In order to automate the data transfer an SSH key pair with public key authentication was implemented between the two computers. To the existing software a script as well as a class controlling the three automation aspects were added. From the user interface, the class initially retrieves information about the acquisition settings to the folder name and when the acquisition is complete, the program code calls the script file that performs the SCP transfer. Afterwards a verification is made that no data was lost during the transfer, after which a deletion of the copied files is performed on the original disk. The new class improves the usability of the micro-CT and facilitates the handling of data after an acquisition.

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The viscoelastic behavior of concrete, nearly completely attributable to changes in properties in the cement paste, is an ongoing area of research with the objective of avoiding unpredictable response and potentially failure of concrete structures. This research explores the elastic and viscoelastic response in cement paste beams using relaxation testing, with and without strain reversals in the load history. It was seen that strain reversal imparts significant changes in mechanical response, retarding load relaxation. Companion beams were tested for chemical composition at varying depths in the beam section and the results were compared to those of control specimens not subject to stress. Results indicate significant variations in composition implying that stress accelerates the hydration process. The reasons behind the acceleration are discussed and incorporated into a preliminary solidification-dissolution model for beam relaxation. The model, though in need of improvement through further research, shows promise in potentially predicting relaxation in cement paste and by extension, in concrete structures. / Ph. D.

The objective of this thesis is to provide an improved characterization of porous scaffolds. A more focused objective is to provide a computational model simulating the cell mediated resorption process of resorbable bone substitutes. The thesis is structured in three scientific manuscripts. The first manuscript used fuzzy-based image treatment methods to analyse images generated by micro-computed tomography. From the literature, it is known that the fuzzy-based method helps to improve the accuracy of the characterization, in particular for scaffolds featuring a relatively small pore size. In addition, a new algorithm was introduced to determine both pore and interconnection sizes. The surface area of bone substitutes was quantified by using marching cube algorithm. Besides, the so-called Lattice Boltzmann method was used to characterize the permeability of the investigated scaffolds. Scaffolds made of [béta]-tricalcium phosphate ([béta]-Ca[subscript 3](PO[subscript 4])[subscript 2]) and presenting a constant porosity and four variable pore sizes were examined. The average pore size (diameter) of the four bone substitute groups (denominated with a letter from group A to D) was measured to be 170.3«1.7, 217.3«5.2, 415.8«18.8 and 972.3«10.9 [micro]m. Despite this significant change in pore size, the pore interconnection size only increased slightly, in the range of 61.7 to 85.2 [micro]m. The average porosity of the four groups was 52.3«1.5 %. The surface density of scaffolds decreased from 11.5 to 3.3 mm[superscript -1], when the pore size increased. The results revealed that the permeability of scaffolds is in the same order of magnitude and increased from 1.1?10[superscript -10] to 4.1?10[superscript -10] m[superscript 2] with increasing the pore size. The second manuscript was devoted to the use of subvoxelization algorithm and high-resolution scanner, in an attempt to further improve the accuracy of the results, in particular, of the small pore scaffolds. As expected, an increase of the image resolution from 15 to 7.5 [micro]m significantly eased the segmentation process and hence improved scaffold characterization. Subvoxelization also improved the results specifically in terms of interconnection sizes. Specifically, much smaller interconnection sizes were yielded after applying the subvoxelization process. For example, the mean interconnection size of small pore size groups, group A and B, dropped from 63 to 20 and 30 [micro]m, respectively. Furthermore, due to more details obtained from subvoxelization and high-resolution scanning, additional effects so called"boundary effects" were observed. The boundary effects can yield misleading results in terms of interconnection sizes. The means to reduce these effects were proposed. The third manuscript focused on the simulation and understanding of cell mediated resorption of bone graft substitutes. A computer model was developed to simulate the resorption process of four bone substitute groups. [mu]CT data and new"image processing" tools such as labelling and skeletonization were combined in an algorithm to perform the steps of resorption simulation algorithm. The proposed algorithm was verified by comparing simulation results with the analytical results of a simple geometry and biological in vivo data of bone substitutes. A correlation coefficient between the simulation results and both analytical and experimental data, was found to be larger than 0.9. Local resorption process revealed faster resorption in external region specifically at earlier resorption time. This finding is in agreement with the in vivo results. Two definitions were introduced to estimate the resorption rate; volume resorption rate and linear resorption rate. The volume resorption rate was proportional to accessible surface and decreased when the pore size increased, while the linear resorption rate was proportional to thickness of material and increased with increasing the pore size. In addition, the simulation results revealed no effect of resorption direction on resorption behaviour of substitutes. However, the resorption rate of small pore size samples was decreased with increasing the minimum interconnection size required for cell ingrowth, to 100 [micro]m. This thesis combined novel"image processing" tools and subvoxelization method to improve the characterization of porous bone substitutes used in the bone repair process. The improved characterization allowed a more accurate simulation process. The simulation data were consistent with previously obtained biological data of the same group and allows understanding the local resorption process. The available tools and results are expected to help with the design of optimal substitute for bone repair."--Résumé abrégé par UMI.

Thesis written in co-mentorship with director: Nelly Huynh; co-directors: Frank Rauch and Jean-Marc Retrouvey; collaborators: Clarice Nishio, Duy-Dat Vu and Nathalie Alos / Introduction - L'ostéogenèse imparfaite (OI) est une maladie osseuse héréditaire qui affecte la production du collagène de type I et le remodelage osseux. Les biphosphonates sont administrés aux enfants atteints d'OI dans le but d’augmenter la masse osseuse et de réduire les fractures osseuses. Les patients atteints d’OI ont des malocclusions sévères qui affectent leur qualité de vie. Plusieurs processus biologiques de remodelage osseux qui sont nécessaires pour un mouvement dentaire orthodontique sont affectés chez les gens atteints d’OI. L'objectif de cette étude est d'évaluer le mouvement dentaire orthodontique dans un modèle de souris avec OI et traitées aux biphosphonates. Matériels et méthodes - Vingt-quatre souris femelles âgées de 10 semaines ont été divisés en 4 groupes : 1 - OI traitées par zolédronate (n=6); 2 - OI non traitées (n=6); 3 - Type sauvage traitées par zolédronate (n=6); 4 – Type sauvage non traitées (n=6) Un ressort de nickel-titane activé à 10 g de force a été cimenté entre les incisives et la 1ère molaire maxillaire droite. Le côté contralatéral a été utilisé comme témoin. Une dose de 0,05 mg de zolédronate a été administrée par voie sous-cutanée un jour avant la chirurgie. Sept jours après l'intervention, les souris ont été euthanasiées et la distance entre la 1ère et la 2e molaire a été mesurée par analyse microtomographique. Résultats - Le mouvement dentaire orthodontique était significativement plus important chez les souris OI que celles de types sauvages dans les groupes non traités (p < 0,05). Le traitement par zolédronate n'a eu aucun effet significatif sur le mouvement dentaire orthodontique au sein des groupes OI et type sauvages. Conclusions - Ces résultats suggèrent une augmentation du mouvement dentaire orthodontique chez les souris avec l’ostéogenèse imparfaite. / INTRODUCTION - Osteogenesis imperfecta (OI) is a heritable bone disorder that affects collagen type I production and bone remodeling. Orthodontic tooth movement (OTM) involves the underlying process of alveolar bone remodeling. The objective of this study is to evaluate OTM in a mouse model of OI. METHODS - Twenty four, 10 week-old female mice were divided into 4 groups: 1- OI treated with zoledronate, 2- OI untreated, 3- Wild-type (WT) treated with zoledronate and 4- WT untreated. A nickel-titanium closed coil spring (10 g) was attached between the incisors and the right maxillary 1st molar. The contralateral side was used as control. Zoledronate (0.05mg/kg) was administered sub-cutaneously 1 day prior to surgery. Seven days after the procedure, the distance between 1st – 2nd molars was measured by micro-CT. RESULTS - OI mice presented significantly more OTM than WT mice when comparing within untreated groups (p<0.05). Zoledronate treatment had no significant effect on OTM within OI and WT groups. CONCLUSIONS - These results suggest increased OTM in mice with OI. The dose of zoledronate administrated 1 day prior to surgery had no significant effect on OTM.

No description available.

Made available in DSpace on 2017-07-24T19:21:57Z (GMT). No. of bitstreams: 1 Patricio Runnacles.pdf: 1899405 bytes, checksum: f12074a5a86f43aa25ef7c17d1ba8e87 (MD5) Previous issue date: 2014-12-17 / Objective: This in vivo study evaluated the baseline pulp temperature in human intact upper premolars and the pulp temperature rise induced by light emitted by a high power polywave Light Emitting Diode (LED) light curing unit (LCU); also, the possible correlation between the change in temperature (ΔT) and the volume of the crown and the pulp chamber ex vivo. Material and methods: after approval of the local Ethics Committee was obtained (protocol #255,945), upper right and left first premolars requiring extraction for orthodontic reasons from 8 volunteers (n=15) received infiltrative and intraligamental anesthesia and were isolated using rubber dam. A small, occlusal preparation was made using high-speed hand piece, under constant air-water spray, until a minute pulp exposure was attained. The sterile probe from a wireless, NIST-traceable, temperature acquisition system (Temperature Data Acquisition - Thermes WFI, Physitemp) was inserted directly into the coronal pulp. Once the baseline pulp temperature was stable, the buccal surface was exposed to polywave light from a LED LCU (Bluephase 20i, Ivoclar Vivadent) using selected EMs: 10-s either in low (10-s/L) or High (10-s/H); 5-s-Turbo (5-s/T); and 60-s-High (60-s/H) intensities, allowing a 7-min span between each exposure. Peak PT values and PT increases from baseline (ΔT) after exposure were subjected to 1-Way, repeated measures ANOVAs, and Bonferroni's post-hoc tests (α=0.05). Linear regression analysis was performed to establish the relationship between applied radiant exposure and ΔT. Linear regression analysis was performed to establish the relationship between applied radiant exposure and ΔT. the teeth were extracted according to treatment plan. The crown and pulp volumes were measured using micro-tomography scanner, and pulp chamber / crown volume ratio was determined. Afterwards, premolar buccal-lingual, cervico-occlusal, mesio-distal dimensions as well as between cusp distances were measured using a digital caliper. Results: consistent temperature below body temperature, resulting in an average core temperature of 35 ° C (+ 0.7 ° C) was found. All modes of activation of the LED promoted significant temperature rise in the pulp chamber. A positive correlation between energy density and thermal variation was observed. No correlation was observed between coronal volume, the pulp chamber with temperature changes. A significant negative correlation was noted between pulp temperature changes when 10-s/L was used and VL. / Objetivo: Este estudo in vivo avaliou a temperatura basal da polpa em pré-molares hígidos superiores em humanos e o aumento da temperatura induzida pela luz emitida por um fotopolimerizador à base de Diodo Emissor de Luz (LED) polywave de alta potência; além disso, a possível correlação entre a variação de temperatura (ΔT) e o volume da coroa e da câmara pulpar ex vivo. Material e métodos: após aprovação da Comissão de Ética da Universidade Estadual de Ponta Grossa (UEPG) (protocolo #255,945), pré-molares direito e esquerdo de 8 pacientes voluntários (n=15), que necessitavam de extrações por motivos ortodônticos, receberam anestesia infiltrativa e intraligamentar e isolamento absoluto. Um pequeno acesso oclusal com exposição pulpar foi realizado usando alta-rotação, sob spray de ar e água constante, até atingir uma mínima exposição da polpa. Inseriu-se uma sonda estéril de um termopar wireless (Temperature Data Acquisition - Thermes WFI, Physitemp) diretamente no interior da câmara pulpar. Após a estabilização da temperatura basal da polpa, a face vestibular foi exposta à luz de um fotopolimerizador LED polywave (Bluephase 20i, Ivoclar Vivadent), usando modos de exposição selecionados: 10s em baixa potência (10s/L), 10s em alta potência (10s/H), 5s em potência turbo (5s/T) e 60s em alta potência (60s/H), respeitando um intervalo de 7 min entre cada exposição. A temperatura pulpar foi registrada a cada 0,2 s. Os valores absolutos e a variação da temperatura pulpar após exposição foram submetidos a análise estatística fator único (ANOVA) com medidas repetidas seguida pelo teste de Bonferroni (α=0,05). A correlação entre as densidades de energia aplicadas e os valores das variações de aumento de temperatura foi estabelecida por uma análise de regressão linear. Após as exodontias realizadas de acordo com os planos de tratamento, os elementos dentários (n=11) foram armazenados em Timol 0,1% e as dimensões mésio-distal da face oclusal (MD), cérvico-oclusal (CO), e vestíbulo-lingual (VL) da coroa dos dentes foram medidas com um paquímetro digital. Os volumes coronário e da câmara pulpar foram determinados por meio de microtomografia computadorizada (μCT) dos espécimes. Resultados: foi encontrada uma temperatura basal média consistente abaixo da temperatura corporal, de 35°C (+ 0,7°C). Todos os modos de ativação do LED promoveram aumento significativo de temperatura na câmara pulpar. Foi observada uma correlação positiva entre densidade de energia e variação térmica. Não houve correlação dos volumes coronal e da câmara pulpar com as variações térmicas, mas foi encontrada uma correlação negativa entre a medida VL das coroas e o ΔT no modo de exposição 10s/L.