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Statement of the problem: Conventional techniques for implant framework fabrication have been shown to produce errors that are inconsistent with the passive-fit requirement for osseointegrated implant frameworks. Purpose: The aim of this study was to assess the three-dimensional distortion inherent in casting of full arch, screw-retained titanium implant frameworks. Materials and methods: A conventional commercial laboratory one-piece casting, using the lost-wax technique was used. Five wax patterns were fabricated on a die-stone cast poured from a plaster impression of a five-fixture brass analogue. A reflex microscope was used to determine the three-dimensional casting error, by measuring horizontal and vertical distances for each wax pattern and its corresponding cast titanium framework, as well as offset distances from the horizontal reference plane. Results: Significant differences were found in the amount of distortion between wax patterns and cast frameworks, with the castings being approximately 416 μm to 477 μm larger than the wax frameworks. The greatest amount of distortion occurred at the terminal implant abutments, and in the vertical dimension. However, there was inconsistency in these differences, indicating the three-dimensional nature of the overall distortion of the cast frameworks. Conclusions: It is doubtful whether any conventionally cast framework can be made to the degree of accuracy required to fit passively on its abutments because of the multiple variables inherent in this process. It is therefore recommended that all full-arch, cast titanium frameworks be cast in sections, or alternatively be sectioned, indexed and soldered before being seated intraorally.

Thesis advisor: Celeste Wells / As a young woman who plans on pursuing acting after graduation, I have begun to learn how I must craft myself in the professional world. In theatre, the importance of accurately portraying one’s “type” is a concept that has been consistently stressed. One sees the irony of “type” if they consider the very premise of acting, to portray someone other than oneself. If acting is actually “living truthfully under imaginary circumstances” as Meisner suggests, then any actor should be able to play any role. However, actors are constantly pigeonholed into roles that objectify them to a particular type. Academic research has failed to sufficiently address casting conventions, especially in theatre. My study aims to address this gap by gaining insight on casting practices from the director’s perspective. To put it simply, it is my hope that this thesis will reveal the intricacies of casting, including the prevalence of type. Consequently, this will generate a better understanding of the process so that others and myself can learn how to breed success and simultaneously maintain our dignity whilst adhering to a field that requires one to brand themself. / Thesis (BA) — Boston College, 2017. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Communication.

Gypsum has been used almost exclusively as the mould material for casting sanitary-ware due to its high versatility, strength and homogenous pore distribution. However gypsum moulds have a number of disadvantages including deterioration on contact with water, deformation, long set times and short mould lives such that a large number of moulds are required for a commercial manufacturing processes. These drawbacks have led to attempts to find a new synthetic material to create moulds with similar properties to gypsum with respect to fine homogeneous pores, but with increased durability. Porous PMMA was developed in 1971 for the purpose of moulding ceramics. The basic approach to making the materials has remained unchanged since its commercial introduction with few academic studies undertaken on the formulations. This thesis describes an investigation into porous PMMA from an academic perspective studying the mechanism of formation of the materials and the role of the components in polymerisation. In particular: the surfactant type and level, monomer type, water to monomer ratio and bead size have been probed to assess their effect on the porosity and mechanical strength. A particular importance has been placed on the commercial viability of formulations because gypsum is a relatively inexpensive material and, due to its versatility and ease of manufacture, is still used throughout the ceramics industry. To increase cost competitiveness through spreading the higher cost of the raw materials and capital investment, the mechanical strength of porous PMMA materials has to be significantly greater to increase the number of casting cycles from each mould. In addition, to achieve competitive advantage in the marketplace, a deep understanding of the formulation was undertaken. This should allow for tailoring of the mould properties allowing for specialised moulds for different applications. In addition, this focused approach facilitates cost-savings allowing for the minimum input of raw materials. The thesis is a comprehensive body of work which looks individually at the components assessing their effect on the properties of the final material. In addition, the formation mechanism of the materials has been explored by breaking down the polymerisation into key stages. Highlighted is the excessive use of surfactant in a commercial formulation and the influence of plasticisation of the ligaments by the surfactant and excess monomer. The theory behind the polymerisation process, which generates the ligaments and traps the polymer beads in an immobile matrix, is developed; forming a comprehensive understanding of the formation of porous PMMA materials and factors influencing their development and final properties.