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Det ökade intresset av keramiska material har främst centrerat kring zirkoniabaserade keramer på sistone. Zirkoniabaserade fastsittande broar är ämne för en pågående diskussion. Det finns några få publicerade studier på ämnet men med varierande kvalitet och det finns ingen sammanställning av implantatstödda zirkoniabaserade broar. Syftet med den här studien är att bedöma tillgängliga studier på tidigare nämnda konstruktion och redogöra för resultat från kliniska studier.På elektroniska databaser söktes artiklar på implantatstödda zirkoniabaserade fastsittande broar. Artiklar som också rörde tandstödda konstruktioner inkluderades i sökningen. Sökningen kompletterades med en manuell referenssök på de utvalda fulltextartiklarna. Sökningen resulterade i 4,253 artiklar. Baserat på förutbestämda kriterier inhämtades 5 fulltext artiklar. En av de studierna skilde inte på tandstödda och implantatstödda grupper i resultatet, därför exkluderaderades den från fortsatta analyser. Tre studier redogjorde för helkäkeskonstruktioner, och majoriteten av de inkluderade konstruktionerna var helkäkeskonstruktioner. Tillräcklig data för uträkning av överlevnad och komplikationsrisk var tillgänglig i 4 studier. Analysen bar baserad på 47 implantatstödda konstruktioner. Slutsatsen av litteraturstudien blir att zirkoniabaserade helkäkeskonstruktioner som är implantatstödda kan övervägas som behandling. Resultaten är dock baserade på få studier med relativt få konstruktioner inkluderade, varför tolkning av resultaten bör göras med försiktighet. Fortsatta studier behövs för att konkludera hur den här typen av konstruktioner håller med tiden. / The increasing interest in ceramic materials has mostly centered on zirconia-based ceramics lately. Zirconia-based fixed dental prostheses (FDPs) is an ongoing subject of discussion. There are a few articles published on the subject but with varying quality and there is no review on implant-supported zirconia-based FDPs to be found. The purpose of this study is to evaluate available studies on zirconia-based implant-supported FDPs, reporting the results from clinical studies.Three electronic databases were searched for studies reporting on zirconia-based FDPs. The electronic search was complemented by a hand-search made from the reference lists of the retrieved full-text articles. The search result yielded 4,253 titles. Based on pre-established criteria, 5 full-text articles were obtained. One study did not separate the results between tooth-supported and implant-supported groups, why it was excluded from further analysis. Three studies reported on cross-arch restorations, and the majority of the FDPs included were cross-arch restorations. Sufficient data for calculation of cumulative survival-and complication-rates was available in 4 studies. Analysis was based on 47 implant-supported FDPs. This review concludes that cross-arch implant-supported zirconia-based FDPs could be considered as a treatment alternative. The results are, however, based on small number of studies with relatively few FDPs included thus interpretation of the results should be made with caution. Further studies are needed to evaluate how these types of constructions stand the test of time.

SAMMANFATTNING  Syfte  Syftet med studien var att undersöka huruvida färginfiltrering med effektfärg påverkar böjhållfastheten i flerskiktad zirkonia.  Material och metod Zirkoniamaterialet KATANA™ Zirconia YML, Kuraray Noritake användes i studien. Totalt framställdes 54 stycken provkroppar varav sex stycken utgjorde en pilotstudie för polering. Resterande 48 delades in i sex grupper (n = 8). Tre av grupperna frästes ut från Emalj och Body 1 (E-B1) och de resterande tre grupperna frästes ut från Body 2 och Body 3 (B2-B3). Två grupper, från de olika skikten, infiltrerades med Esthetic Colorant A plus (A), två grupper infiltrerades med Esthetic Colorant Opaque (O) samt två grupper utgjorde kontrollgrupper utan infiltrering (K). Provkropparna infiltrerades och sintrades enligt fabrikantens anvisningar. Därefter polerades de enligt ett poleringsschema och slutligen genomfördes ett biaxialt böjhållfasthetstest. Resultaten från samtliga grupper analyserades med One-way ANOVA, Tukey’s test, med en signifikansnivå på α = 0,05 med hjälp av statistikprogrammet SPSS.  Resultat Resultatet påvisade ingen signifikant skillnad i böjhållfastheten inom grupperna för de två skikten (E-B1A, E-B1O och E-B1K) samt (B2-B3A, B2-B3O och B2-B3K). Grupperna med skikten som inkluderade B2-B3 uppvisade signifikant högre böjhållfasthet oavsett infiltrering/kontroll än grupperna E-B1A, E-B1O och E-B1K.   Slutsats Böjhållfastheten i flerskiktad zirkonia påverkas inte av infiltrering med effektfärg. / ABSTRACT Purpose The purpose of this in vitro study was to investigate whether color infiltration with effect colors affect the biaxial flexural strength of multilayer zirconia.   Material and method The zirconia material KATANA™ Zirconia YML, Kuraray Noritake was used in the study. A total of 54 specimens were produced, of which six were part of a pilot study for polishing. The remaining 48 were divided into six groups (n=8). Three of the groups were milled of Enamel and Body 1 (E-B1) and the remaining three groups were milled of Body 2 and Body 3 (B2-B3). Two groups, from the different layers, were colored with Esthetic Colorant A plus (A), two groups were colored with Esthetic Colorant Opaque (O), while two groups served as control groups (K). The specimens were colored and sintered according to the manufacturer's instructions, polished according to a polishing schedule, and finally a biaxial flexural strength test was performed. The results were analyzed using One-way ANOVA, Tukey's test, with a significance level of α = 0.05 using the statistical software SPSS.   Results The results showed no significant difference in flexural strength within the groups for the two layers (E-B1A, E-B1O, and E-B1K) and (B2-B3A, B2-B3O, and B2-B3K). The groups with layers that included B2-B3 showed significantly higher flexural strength regardless of coloring/control than the groups E-B1A, E-B1O, and E-B1K.  Conclusion The flexural strength of multilayered zirconia is not affected by color infiltration with effect colors.

To meet the requirements of precise temperature monitoring at high temperatures in extremely corrosive environments, such as in coal gasifiers, a new sensor technology has been developed. This optical, ultra high temperature measurement system utilizes single crystal sapphire as a sensing element. A series of experiments was performed to determine the corrosion resistance of single crystal sapphire and single crystal fully stabilized cubic zirconia at high temperatures in coal slag and soda lime glass. The amount of corrosion of sapphire and zirconia in corrosive slags was measured at 1200°C, 1300°C, and 1400°C for different exposure times. The microstructural features at the interface of sapphire and zirconia were investigated using SEM and EDX analysis. The experimental measurements as well as SEM micrographs show very little or no degradation of sapphire and zirconia samples in corrosive slags. An interesting phenomenon was observed in the EDX scans of sapphire in the coal slag: the iron from the slag appears to have completely separated from the silicon and deposited at the sapphire surface. This interesting observation can be further explored to study whether this iron layer can be used to control the corrosion of sapphire. / Master of Science

OBJECTIVES: This study aims to fill these voids in the literature regarding the microstructure, mechanical and optical properties of multilayered zirconia subjected to repeated firing. It will aim to increase knowledge and understanding of this type of novel material, whether multilayered by chroma or composition. MATERIALS AND METHODOLOGY: The three materials examined are ZirCAD Prime by Ivoclar Vivadent, Origin Beyond+ Hybrid by B and D Dental Technologies, and Katana HTML by Kuraray Noritake. Beam-shaped specimens were sectioned to the correct size from discs of the three zirconia materials and subsequently cleaned, polished, and annealed. Ten specimens taken from each group were subjected to one, three, and five repeated firings, which were then used for the destructive flexural strength test using a universal testing machine. Another set of smaller specimens were produced and used for the non-destructive tests, prepared in the same manner as the other specimens, with 2 samples present in each group. These small specimens were examined for the following properties: contrast ratio and CIELAB measurements on a white and black background using a spectrophotometer, crystallographic phase changes using x-ray diffraction (XRD), and elemental analysis using energy dispersive spectroscopy (EDS). RESULTS: Repeated firings did not have any significant effects across all brands of materials for all tests conducted. However, significant differences existed between the different materials, and within their different layers for all tests conducted unrelated to repeated firing. Significant differences only existed in flexural strength depending on annealing, polishing status, type of polishing, and size independent of repeated firing. Annealing yielded weaker specimens than non-annealed, polished specimens were stronger than non-polished ones, automated polishing resulted in stronger specimens than manually polished ones, and smaller specimens were stronger than larger ones in terms of flexural strength. CONCLUSIONS: Within the limitations of this study, repeated firing has no significant effects on the various multilayered zirconia tested in this study. There is a significant difference in flexural strength between the materials studied. Significant differences in flexural strength also existed between specimens that were annealed versus ones that were not; and between specimens that were polished versus ones that were not. This study has increased knowledge regarding this novel material.

Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) method whereby complex parts can be built to near net geometry in an automated environment. Parts formed by LPBF have excellent properties and require little post-processing. While LPBF allows for creative designs to reduce weight and part count by integrating sub-components of assemblies, designers are limited to one material within any LPBF print. Although various materials can be used in LPBF, metals are of special interest to many industrial customers due to their high strength and toughness. The metals commonly used for LPBF include iron, aluminum, and titanium alloys. These alloys are generally designed to fulfill specific needs and even small variations in composition are detrimental to the functionality. However, some alloys are intentionally modified to achieve specific results. For example, Yttria is dispersed in stainless steel to enhance its resistance to radiation damage. The sensitivity of metal alloys to small changes in composition can be exploited to change the properties of LPBF material within a single print. An en-situ doping technique, which is under development, allows for the introduction of small quantities of liquid-suspended additives to any part of the powder bed. The liquid is then evaporated, and these additives integrate with the solid material upon laser fusion to change the properties of the base material. In this thesis, steel-insoluble (zirconia) and soluble (carbon) dopants are introduced into multi-layer parts formed by LPBF. Zirconia significantly increased the porosity of the steel with continuous pores which disrupt the columnar grain structure. The majority of the added zirconia segregated to the outer surface and porous surfaces within the bulk. Although hardness did not increase as expected, the porosity can aid in osseointegration when used for implants, or as a reduced-conductivity thermal barrier in heat sensitive applications. Carbon-doped samples, on the other hand, had nearly 30% increased hardness and more homogeneous microstructure than unmodified material. Hardened surfaces may be a valuable tool for designers who require wear resistance. Although porosity increased from ~0% to over 10% in the worst case, modified parameters resulted in only 1% porosity. The data indicate that changing the processing conditions affects porosity, so the amount of porosity could be adjusted. Finally, carbon was shown to create preferential etching which enables easy removal of support structures. Supports doped with carbon to promote sensitization and etched in an electrolyte bath either broke free without tension, or using no more than 20% of the force required to remove unmodified supports. This is a valuable step for reducing the post-processing required of many LPBF designs.

Cette thèse porte sur l'évaluation de la réponse cellulaire in vitro vis-à-vis de différentes stratégies de modification de surface pour améliorer la capacité d’ostéointégration de céramiques bioinertes pour implants orthopédiques et dentaires. Premièrement des surfaces l'alumine-zircone avec différentes micro-rugosités obtenues par moulage par injection ont été étudiées. Le comportement d'ostéoblastes primaires humains (obtenus à partir de têtes de fémurs soumis à arthroplastie) a été étudié sur les surfaces telles quelles ou modifiées par traitement avec acide hydrofluorique. La micro-rugosité a eu seulement un effet mineur sur la réponse ostéoblastique tandis que la combinaison de micro- et nano-rugosité a eu un effet synergique sur la maturation ostéoblastique. Cette stratégie de modification de surface ouvre la voie vers des cupules acétabulaires céramiques monoblocs directement ostéo-intégrées. Deuxièmement, le robocasting (une technique d’impression 3D) a été exploré pour la production de structures macroporeuses en alumine-zircone avec une haute reproductibilité et contrôle architectural. Les structures imprimées ont présentées une topographie aux multiples niveaux grâce au design et les conditions de frittage. Les ostéoblastes ont pu s'attacher sur les structures 3D mais la préservation des cellules à l’intérieur des scaffolds sur le long terme reste à améliorer. Des techniques de sélection rapide de modifications de surface ont fait l'objet de la dernière partie de cette thèse. Deux différentes stratégies ont été utilisées sur la zircone: laser femtoseconde pour la production de multiples motifs sur un échantillon unique et échantillons avec un gradient de rugosité via le contrôle du temps d’attaque chimique. La morphologie des cellules souches humaines a permis d'avoir un indicateur précoce de la lignée de différentiation cellulaire. En conclusion, les différentes techniques de modification de surface de zircone et alumine-zircone utilisées à travers la thèse peuvent moduler l’interaction cellule-matériau en stimulant la différentiation ostéoblastique de cellules souches et la maturation des ostéoblastes. / The focus of this PhD thesis is the in vitro evaluation of cell-material interactions on bioinert ceramics with novel surface modifications for enhanced osseointegration of orthopaedic and dental implants. Firstly, alumina-zirconia surfaces with different micro-roughnesses obtained by injection moulding were studied. The behaviour of human primary osteoblasts (hObs) obtained from patients undergoing total hip replacements was studied on the different micro-rough ZTA surfaces and on combined micro-/nano-rough surfaces modified by hydrofluoric acid treatment. Micro-roughness alone had minor effects on hOb response while the combination micro-/nano-roughness induced a synergic effect on hOb maturation. This latter surface modification technique opens the way to the fabrication of ceramic acetabular cups with direct implantation capabilities. Secondly, robocasting (a 3D printing technique) was explored for the fabrication of a alumina-zirconia macroporous structures with high reproducibility and control of the architecture. Roughness at different scales was observed for the 3D structures due to the scaffold design and to the low temperature sintering conditions. Osteoblasts were able to attach on the 3D structures but cell retention at long term needs further optimization. Rapid screening of cell-material interactions was the subject of the last part of the thesis. Two different strategies were tested on zirconia: femtosecond laser to produce multiple patterns on a single sample and samples with a roughness gradient by the control of chemical etching time. Stem cell morphology was used as an early marker of cell differentiation lineage. In conclusion, the different surface modification techniques of zirconia and alumina-zirconia surfaces used in the thesis allow the modulation of cell-material interactions by stimulating stem cells osteogenesis and osteoblast maturation.