Across vertebrates, the coordinated evolution and synchronous development of teeth and the mandible must require specific timing and positioning of gene expression. While debate persists about whether teeth have evolved before or after mandible, currently, the consensus is that these systems evolved at separate times and thus have discreet origins. This raises an important question of whether tooth and mandibular tissues have over the course of their evolution become developmentally co-dependent or, as separate evolutionary origins would imply, remain developmentally autonomous of each other. The molecular signaling that patterns the genesis of upper versus lower jaw skeletons, as well as specifies tooth type (i.e., molar vs. incisor) is relatively well understood. To date, the distinct genetic processes that drive tooth development distinct from jaw skeletal development has been little-studied, in no small part due to the technical complexity of this task. The main hypothesis of thesis is that a collection of genes acting within a gene regulatory network (GRN) drives odontogenesis with neither input from, nor influence on, jaw morphogenesis. The Transformation Related Protein (TRP63) is a master transcription factor that is vital to odontogenesis because TRP63 maintains the competence and proliferation of the epithelial layer of the tooth organ. Thus the “toothless” TRP63 homozygote mouse mutant (Brdm2 mutant) fails to develop teeth even though it develops a virtually unperturbed mandible. This combination of lower jaw morphogenesis in the absence of odontogenesis presents a rare model to study the genetic changes that occur when teeth but not jaws fail to form. A previous microarray gene expression analysis (Boughner laboratory, unpublished data) of mandibular prominences (MdPs) derived from embryonic day (E) 10-13 revealed that, compared to heterozygote (Trp63+/-) MdPs, in Brdm2 mutant MdPs, transcript levels of cerebellin 1 (Cbln1); keratin 2-8 (Krt2-8); phospholipid transfer protein (Pltp) and fermitin 1 (Fermt1) were altered in at least some of the four embryonic stages. Specifically Cbln1 and Krt2-8 were up-regulated while Pltp and Fermt1 were down-regulated. None of these four genes have previously been linked to odontogenesis yet all are potential candidates for a “tooth-specific” GRN. Using RT-qPCR analysis, I aimed to test the validity of the microarray work and confirmed its veracity by showing that, generally, Cbln1 and Krt2-8 mRNA were up-regulated, while Fermt1 (but not Trp63 or Pltp) mRNA was significantly down-regulated in the MdPs of Brdm2 mutant mice relative to Trp63+/- mice. Conversely, western blotting protein expression analysis showed little-to-no change among Brdm2 MdPs relative to either wild type (Trp63 +/+) or Trp63+/- embryos, making it difficult to tease out the precise relationship between CBLN1, FERMT1, KRT2-8, and PLTP and TRP63. These results show a lack of strong correlation between mRNA and protein expression. Because the mRNA analyses showed disturbances in the expression level in a few of these five genes within the MdPs during the earliest stages of tooth development, these genes remain candidates for an odonto-specific GRN. In complement to the genetic work, to characterize the tandem developmental morphology of tooth and jaw skeleton tissues, my work included developing a new tissue staining protocol. Using Protargol, a silver-based compound, to enhance in uncut mouse embryos contrast among tiny, soft oral tissues and visualize their organization in 3D and microscopic detail across several embryonic stages. This novel protocol offers a simple, easy-to-follow, and relatively inexpensive way to effectively stain whole embryos aged E10-15 for X-ray based micro-computed tomography (μ-CT) imaging using synchrotron and desktop scanning systems. Because the scan data are digital, this new method also allows more precise, accurate and rapid empirical studies of the sizes, shapes and positions of teeth as they form within the jaw to clarify how these tissues are integrated as they develop. The work presented in this thesis investigated tooth development exclusive of mandible development from complementary molecular and morphological points of view. Driven by the lack of understanding of the genetic mechanisms that orchestrate tooth with jaw skeletal development, this study has for the first time isolated a set of genes that are potential candidates for tooth formation only. These results set the stage for next steps in testing the developmental-genetics that enable teeth and jaws to “fit” together as they develop.

Cortical bone is a dynamic tissue which undergoes adaptive and pathological changes throughout life. An improved understanding of the spatio-temporal process of remodeling holds great promise for improving our understanding of bone development, maintenance and senescence. The use of micro-computed tomography (µCT) on living animals is relatively new and allows the three dimensional quantification of change in trabecular bone microarchitecture over time. The use of in vivo µCT is limited by the radiation dose created by the x-ray beam, with commercially available in vivo systems generally operating in the 10-20 um resolution range and delivering an absorbed dose between 0.5-1 Gy. Because dose scales to the power of four with resolution, in vivo imaging of the cortical canal network, which requires a higher resolution, has not been achieved. I hypothesized that using synchrotron propagation phase contrast µCT, cortical porosity could be imaged in vivo in rats at a dose on the same level as those used currently for trabecular bone analysis. Using the BMIT-BM beamline, I determined the optimal propagation distance and used ion chamber and lithium fluoride crystal thermoluminescent dosimetry to measure the absorbed dose of my in vivo protocol as well as several ex vivo protocols using synchrotron phase contrast µCT at 5 µm, 10 µm, and 11.8 µm and conventional desktop in vivo protocols using commercial µCT systems. Using synchrotron propagation phase contrast µCT, I scanned the forelimb of two adult Sprague-Dawley rats and measured an absorbed dose of 2.53 Gy. Using two commercial µCT system, I measured doses between 1.2-3.6 Gy for protocols at 18µm that are in common use. This thesis represents the first in vivo imaging of rat cortical porosity and demonstrates that an 11.8 µm resolution is enough to visualize cortical porosity in rats, with a dose within the scope of those used for imaging trabecular bone in vivo.

In the area of translational research, stent developers consult pathologists to obtain the best and most complete amount of data from implanted test devices in the most efficient manner. Through the use of micron-scale computed tomography along with post-fixation staining techniques in this study, full volumes of previously implanted stents have been analyzed in-situ in a non-destructive manner. The increased soft tissue contrast imparted by metal-containing stains allowed for a qualitative analysis of the vessel’s response to the implant with greater sensitivity and specificity while reducing beam-hardening artifact from stent struts. The developed staining techniques included iodine-potassium iodide, phosphomolybdic acid, and phosphotungstic acid, all of which bind to soft tissue and improve image quality through their ability to attenuate high energy X-rays. With these stains, the overall soft tissue contrast increased by up to 85 percent and contrast between medial and neointimal layers of the vessel increased by up to 22 percent. Beam hardening artifact was also reduced by up to 38 percent after staining. Acquiring data from the entirety of the stent and the surrounding tissue increased the quality of stent analysis in multiple ways. The three dimensional data enabled a comprehensive analysis of stent performance, lending information such as neointimal hyperplasia, percent stenosis, delineation of vessel wall layers, stent apposition, and stent fractures. By providing morphological data about stent deployment and host response, this method circumvents the need to make the more traditional histology slides for a morphometric analysis. These same data may also be applied to target regions of interest to ensure histology slides are cut from the optimal locations for a more in-depth analysis. The agents involved in such techniques are readily available in most pathology laboratories, are safe to work with, and allow for rapid processing of tissue. The ability to forego histology altogether or to highly focus what histology is performed on a vessel has the potential to hasten the development process of any coronary stent.

Resin composites have been in the dental field for over forty years. They are now thought to be the most commonly used restorative material due to their aesthetic and mechanical properties. Although resin composites have high success rates as restorations, they do not offer all properties of an ideal restorative material. The aims of this research were to characterise the effects of variation in resin composite formulation on handling, mechanical; and physical properties. In particular the influence of the size and distribution of the inorganic components was investigated through the study of experimental formulations. Packing stress and viscosity were assessed with pentrometer principle at two different temperatures (23 and 37 ºC). It was found that filler size was strongly correlated with both packing stress and viscosity. Additionally, temperature has a dominant effect on packing stress and viscosity. Micro computed tomography [μCT] was used to investigate percentage of voids [% voids] in 3D dimensions. It was found that smaller filler size incorporated less % voids. In contrast filler size and disruption had a little effect on fracture toughness of resin composites. 3D surface topography was used to investigate the surface roughness before and after tooth brush abrasion. It was found filler size had a significant influence in both gloss retention and surface roughness (smaller filler size exhibited higher surface gloss). Finally, the effect of different storage media (distilled water, Coca Cola and red wine) on colour stability and gloss were investigated. It was found that dietary habits effect discolouration of resin composite restorations with the acidic drinks caused more staining.

No description available.

No description available.

Objectives: While bracket debonding has been explored through shear bond-strength tests with debonding linked to the type of material used, the technique of adhesive application, and contamination, the contribution of internal voids in orthodontic adhesives is unknown. Voids may result in fracture or bond-failure, either within the adhesive or at the tooth-adhesive-bracket interfaces. The aim of this thesis is to quantify the internal volumetric voids and bonding strength of three generations of bracket adhesives. Methods: Extracted third molars were bonded with three groups of orthodontic brackets including conventionally-pasted (CP), pre-coated (PC), or pre-coated flash-free (FF) (n=5 per group). The three-dimensional internal structure of the adhesive was evaluated with Micro Computed Tomography (micro-CT) using the Skyscan micro-CT (maximum resolution of 5 microns). Data from the micro-CT were analyzed with SkyScan software to perform 3D reconstructions, image processing, and qualitative and quantitative analysis of the adhesive’s structure. The amount of void was determined by measuring the percentage of voids at the bonded interfaces (Vint) and within the adhesive (Vbulk). The total amount of void was also calculated (Vtot= Vint+ Vbulk). Differences in void between the groups were assessed using one-way ANOVA with post-hoc Tukey tests (α=0.05). The bonding strength of the three adhesives systems was evaluated via shear bond strength tests. Results: Our void quantification results showed that FF brackets had a statistically higher (p0.05) for any the analyzed locations (Vint, Vbulk). Our results indicate the majority of voids were found at bonded interfaces (Vint) compared to within the bulk (Vbulk) for all three groups, with statistically significant (p<0.05) differences for CP and FF. Our bonding strength evaluation revealed the pre-coated group (PC) to have on average the highest bond strength compared to conventionally-pasted (CP) and pre-coated flash-free (FF) groups. Conclusions: The overall amount of void in the pre-coated flash-free adhesive brackets is significantly higher compared to conventionally-pasted and pre-coated groups. The majority of the void was identified to be located at the bonded interfaces (tooth/adhesive and bracket/adhesive) rather than within the bulk of the adhesive for all groups. Our bonding strength results indicate the pre-coated brackets to have the highest bond strength compared to pre-coated flash-free and conventionally-pasted. Our preliminary set of results indicate an inverse relationship between bonding strength and amount of void of brackets adhesives, with the pre-coated exhibiting the highest bond strength and least void. However, due to a limited sample size additional data are needed to validate these conclusions and find solid relationships between adhesive voids and bonding strength. / Oral Biology

Submitted by MARCELO LELIS ZUPPARDO (ortodontiazuppardo@hotmail.com) on 2018-08-01T23:43:51Z No. of bitstreams: 1 Versão FINAL 01.08.2018.pdf: 1738428 bytes, checksum: ea89ecbcd914fe55c572f405cd81df64 (MD5) / Approved for entry into archive by Silvana Alvarez null (silvana@ict.unesp.br) on 2018-08-03T12:52:56Z (GMT) No. of bitstreams: 1 zuppardo_ml_dr_sjc.pdf: 1738428 bytes, checksum: ea89ecbcd914fe55c572f405cd81df64 (MD5) / Made available in DSpace on 2018-08-03T12:52:56Z (GMT). No. of bitstreams: 1 zuppardo_ml_dr_sjc.pdf: 1738428 bytes, checksum: ea89ecbcd914fe55c572f405cd81df64 (MD5) Previous issue date: 2018-06-06 / Este estudo comparou dois protocolos cirúrgicos, corticotomia e corticotomia com decorticalização, em ratos para verificar alteração na movimentação ortodôntica convencional. 60 animais foram divididos aleatoriamente: Grupo controle (GC) - movimentação ortodôntica convencional; Grupo 1 (G1) -movimentação ortodôntica e corticotomia; Grupo 2 (G2) - movimentação ortodôntica com corticotomia e decorticalização. Os animais foram eutanasiados após 7 e 14 dias. No G1 e G2 houve uma maior movimentação ortodôntica comparado aos animais do GC aos 14 dias (p = 0,009 e 0,016) com uma maior área radiográfica interradicular, menor volume ósseo/volume total, menor área final e menor porcentagem de osso. Aos 7 dias os animais do G2 apresentaram menor volume de osso/volume total comparado com GC e aos 14 dias os animais do G2 apresentaram uma menor medida linear da crista óssea comparado com o GC. Os animais do GC aos 14 dias apresentaram uma maior área final comparado aos 7 dias, enquanto o G2 apresentou maior número de células TRAP positivas tanto aos 7 quanto aos 14 dias comparado com o G1. Na análise histológica aos 7 dias houve frequente reabsorção radicular inicial geralmente associada às áreas de hialinização e aos 14 dias, presença do infiltrado inflamatório e com menor ocorrência de áreas hialinas. O padrão de reabsorção radicular iniciado no 7º dia de movimento e consolidado no 14º dia. Concluímos que a corticotomia acelera a movimentação ortodôntica em 14 dias independente da magnitude da injúria cirúrgica / This study compared two surgical protocols, corticotomy and decorticalization corticotomy, in rats to verify alteration in conventional orthodontic movement. 60 animals were randomly divided: Group 1 (G1) orthodontic movement and corticotomy, and Group 2 (G2) orthodontic movement with corticotomy and decorticalization. The animals were euthanized after 7 and 14 days. In G1 and G2, there was a greater orthodontic movement compared to CG animals at 14 days (p = 0.009 and 0.016) with a higher interradicular radiographic area, lower bone volume / total volume, lower final area and lower percentage of bone. At 7 days the G2 animals presented lower bone volume / total volume compared to CG and at 14 days G2 animals presented a smaller linear measure of bone crest compared to CG. GC animals at 14 days presented a larger final area compared to 7 days, while G2 presented a higher number of TRAP cells positive at 7 and 14 days compared to G1. In the histological analysis at 7 days, there was frequent initial root resorption generally associated with hyalinization areas and at 14 days, presence of inflammatory infiltrate and less occurrence of hyaline areas. The root resorption pattern started on day 7 of movement and was consolidated on the 14th day. We conclude that corticotomy accelerates orthodontic movement in 14 days regardless of the magnitude of the surgical injury.

Cette étude porte sur l'équipement en bois de cervidé (armement et outillage) fabriqué par les chasseurs-cueilleurs paléolithiques qui peuplaient le massif pyrénéen durant le Magdalénien (19-14 ka cal. BP). Pendant cette période, qui correspond à la fin de la dernière glaciation, les Pyrénées constituent une frontière écologique naturelle, circonscrivant plus ou moins strictement la répartition des cervidés de part et d’autre du massif. La question des usages comparés du bois de cervidé autour des Pyrénées est un cas d'étude particulièrement intéressant pour appréhender les interactions hommes préhistoriques-variations du milieu de part et d’autre d’une frontière écologique naturelle. À travers l’étude techno-économique de sept séries d’industrie sur bois de cervidé du Magdalénien pyrénéen (Santa Catalina-NIII, Isturitz-SI/Eω, Isturitz-I/F1, Troubat-10/8, Belvis-1/4,Canecaude I-2, La Bora Gran), nous avons pu confirmer que les groupes de chasseurs-cueilleurs avaient globalement puisé dans leur environnement proche l’essentiel des ressources dont ils avaient besoin pour leurs équipements.Si les études techniques et économiques comparées que nous avons menées sur ces deux matériaux ne font pas apparaître d’avantages substantiels de l’un par rapport à l’autre, il n’en demeure pas moins que leur exploitation implique dans les deux cas une anticipation des besoins à plus ou moins long terme. En ce sens, le versant nord du massif livre un exemple original de planification des besoins en armement à travers l’exploitation du bois de renne par les groupes du Magdalénien moyen récent et du Magdalénien supérieur ancien. Enfin,pour pallier les problèmes d’identification taxinomique des bois de cervidé (cerf/ renne) liés à la transformation anthropique des vestiges, nous avons développé une nouvelle méthode d’identification des bois de cervidé au micro-CT, combinant microtomographie X et analyses statistiques avancées (SVM classifiers). Cette méthode innovante, dont l’indice de confiance est évalué à 96 %, a permis de démontrer l’importation de bois de renne sur le territoire Ibérique depuis le versant nord du massif. / This study focuses on deer antler equipment (weapon and tool kits) crafted by Palaeolithic hunter-gatherers that inhabited the Pyrenees during the Magdalenian (19-14 ka cal. BP). Throughout this period, which corresponds to the end of the last glaciation, the Pyrenees constitute a natural ecological border, more or less confining the distribution of deer on either side of this mountain range. Comparing the use of deer antler throughout the Pyrenees is a particularly interesting case study for addressing interactions between prehistoric people and environmental variations on either side of a natural ecological border. Through a techno-economic study of seven deerantler industries from the Pyrenean Magdalenian (Santa Catalina-NIII, Isturitz-SI/Eω, Isturitz-I/F1, Troubat-10/8, Belvis-1/4, Canecaude I-2, La Bora Gran), we were able to confirm that hunter-gatherer groups generally exploited their immediate environment for essential resources that they needed for these artefact types. While comparative technical and economic analyses of these two materials do not reveal any substantial advantageof one over the other, their exploitation does however imply in both cases a more or less long-term anticipationof needs. In this sense, the northern side of the range underlines an original example of forward planning of weaponry needs in the exploitation of reindeer antler by Late Middle and Early Upper Magdalenian groups. Finally, in order to overcome problems of taxonomic identification of deer antler (red deer vs. reindeer) tied tothe anthropic transformation of these artefacts, we developed a new identification method using micro-CT scanning,combining X-ray microtomography and advanced statistical analyses (SVM classifiers). This innovative method, with a confidence interval evaluated at 96%, allowed us to demonstrate the import of reindeer antler into the Iberian territory from the northern slopes of the mountain range.

Cette thèse se compose de deux projets individuels et six chapitres, qui sont basées sur l'examen de la structure interne dentaire inférieure dentition postcanine dans un certain nombre de fossiles et modernes spécimens, à travers lesquels une étude approfondie a été effectuée à l'aide de micro-tomodensitométrie et ordinateur-outils de paleonanthropology assistée. Nous avons d'abord recensé et évalué la valeur taxinomique de l'épaisseur de l'émail et des modèles de distribution de l'épaisseur de l'émail 3D entier couronne dans un certain nombre des premiers membres du genre Homo en Afrique du Sud, et examiné dans le relavence taxonomique de EDJ morphologie long postcanine dentition, et discuté de la facteurs d'adaptation possibles / développement qui tiennent compte de la variation de la morphologie EDJ nous avons observé ici. Les trois premiers chapitres (Introduction, Matériel et méthodes) donnent un aperçu des objectifs de cette thèse, et d'examiner les études précédentes. En outre, ils fournissent une introduction détaillée des matières fossiles, les sites et un arrière-plan de la méthode assistée par ordinateur (micro-XCT) pour analyser la structure interne dentaire. Le chapitre des résultats comprend deux documents de recherche indépendants, dans les différentes étapes de soumission et de publication. Les résultats et les chapitres de discussion offrent un résumé détaillé de l'épaisseur de l'émail, EDJ morphométrie géométrique et 3D-EDJ variation métamérique entre les espèces, et de comparer les résultats avec un certain nombre d'études morphologiques et de développement, et de fournir une perspective d'étude future. Le dernier chapitre atteint des points décisifs de cette thèse, il met en évidence la valeur taxinomique des prémolaires EDJ, et met l'accent sur les caractéristiques de la mosaïque de la dentition des premiers membres du genre Homo sud-africaine. / This thesis consists of two individual projects and six chapters, which are based on the examination of dental inner structure of lower postcanine dentition in a number of fossil and modern specimens, through which a comprehensive study has been done using micro-computed tomography and computer-assisted paleonanthropology tools. We first documented and assessed the taxonomical value of enamel thickness and 3D whole-crown enamel thickness distribution patterns in a number of earliest members of the genus Homo in South Africa, and looked into the taxonomic relavence of EDJ morphology along postcanine dentition, and discussed the possible adaptive/developmental factors that account for the variation of EDJ morphology we observed here. The first three chapters (Introduction, Materials and Methods) provide an overview of the objectives of this thesis, and review previous studies. Also, they provide a detailed introduction of fossil materials, sites and a background of computer-aided method (micro-XCT) to analyze the dental inner structure. The Results chapter comprises of two independent research papers, in different stages of submission and publication. The Results and Discussion chapters offer an extensive summary of enamel thickness, EDJ geometric morphometrics and 3D-EDJ metameric variation between species, and compare the results with a number of morphological and developmental studies, and provide an outlook of future study. The last chapter reaches the conclusive points of this thesis, it highlights the taxonomical value of premolar EDJ, and emphasizes the mosaic features of the dentition of South African early Homo.