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This study will develop the basis for a critique of western medicine aimed at providing an analysis, starting from the proposition that any system of medicine must necessarily embody a mysterious quality. What is meant here by mystery is an all-encompassing element of indeterminacy, and so of uncertainty in both the theory and practice of medicine. This analysis will therefore begin by examining the relationship between mystery and medicine. More specific aspects of western medicine will then be considered to show how they have developed so as to produce a reinterpretation or marginalisation of all that is not quantifiable or wholly comprehensible in terms of a particular conception of rationality. The insights ignored gained from this re-evaluation will then be used to develop the outline of a different critique which will indicate ways in which western medicine should be modified in both theory and practice. This will begin the recognition that although the present justification of western medicine is flawed, a more adequate one may be found through re-examining current medical practice and re-orientating it by taking account of particular themes in other contemporary and historical systems of medicine. The unrecognised thread which unites and gives coherence to all these medical systems is the role of mystery. It must be wholeheartedly acknowledged if the current mistakes and problems of western medicine are the revealed and understood, so that more plausible moral and scientific foundations for western medicine can be established.

This thesis traces the development of materials used for denture baseplates and suggests areas for concentrating future research projects. Due to the falling decay rates in many developed countries, the provision of partial rather than full dentures is becoming increasingly common and this places new demands on the baseplate materials. An extensive bibliography has been included which traces the history of the denture materials, their advantages and disadvantages. Despite the fact that it was introduced in the mid 1930s, poly(methyl methacrylate) still remains the material of choice mainly due to low cost and ease of production. However, the use of poly(methyl methacrylate) is limited by it's mechanical properties, and the development of new materials with more suitable characteristics is considered. Traditionally denture teeth have been poorly investigated despite the fact that clinically many dentures fail due to the poor performance of the denture teeth, particularly the excessive wear apparent on many of the occlusal surfaces. By studying the microstructure of natural teeth in detail, a closer understanding of the ways in which they fulfil their functions has been achieved. Scanning Electron Microscopy of the enamel has revealed closely packed crystals arranged in a keyhole configuration whilst a new model has been proposed for the structure of dentine. This new model shows that the material is arranged in basic structural units of approximately 10-20nm across, which coalesce to form a continuous mineral phase. These structures would be consistent with the role of enamel as the protective abrasion resistant layer and with the dentine as the shock absorber, and proposals have been put forward for improving the artificial replacements.

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