Amanda Jane Lewis

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Most of the removable partial denture castings examined showed radiographic evidence of internal porosity. In general the porosity ocurred in characteristic regions associated with abrupt changes in cross-sectional thickness. These were located either within the partial denture framework or at the casting-sprue junctions. The porosity is due to metal(More)
Two types of specimens were cast from a variety of pure metals and alloys. A unidirectional solidification system was used for the production of the first, whilst a deliberate feeding problem was incorporated in the production of the second. The specimens were subjected to radiographic and metallographic evaluation in conjunction with porosity(More)
The fracture of removable partial denture castings does not occur in a random manner but rather at characteristic sites that are determined by the designs of the castings. These sites will be located where elastic stresses resulting either from handling or from normal function are likely to be concentrated. Regions of abrupt change in cross-sectional areas(More)
Three groups of tensile test pieces were produced using a nickel base partial denture castin alloy and employing induction fusion in each case. The first group was produced from new metal, the second from metal which had been recast four times, and the third from new overheated metal. Samples of alloy were cut from each group and, together with a piece from(More)
Three series of tensile test pieces were produced using a nickel base partial denture casting alloy. For the first series induction heating was employed, for the second a resistance crucible, and for the third an oxy-acetylene torch. Samples from each series were sectioned longitudinally, mounted, polished and examined microscopically for evidence of(More)
A metal die simulating a model of a partially dentate upper jaw prepared with milled facets for reference measurement with vernier calipers was used for the making of duplicate stone models, in three different duplicating flasks. The observation showed that irrespective of the flask size, the duplicated models were slightly wider.
A technique for measuring changes in the dimensions of elastomeric impression materials is described. The technique involves using holographic interferometry to determine the rate of dimensional change on setting of the materials. The total change in dimension is found by integration with time. The sensitivity of the technique allows accurate determination(More)
Three series of two types of specimens were cast from a cobalt and a nickel base alloy using variation in mould and metal temperatures and in mould size. The casting procedures included a unidirectional solidification system and a problem of feeding. Porosity was assessed by radiographic and metallographic analyses.