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Title: Mechanical properties of human enamel and dentine and of composite restorative materials
Author: Hannah, Cameron McDonald
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 1974
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In recent investigations adhesive tensile bond strengths of similar magnitude to the supposed tensile strength of enamel have been obtained on the enamel of human teeth. These bonds were reported to have failed either within the cement adherend or at the interface between adherends, but failure of enamel was not reported. Modifications of clinical techniques now permit the direct attachment of stronger materials to enamel by 'mechanical tagging'. In a literature review only one report on the tensile properties of enamel was traced. However, it was noted that conflicting opinions had been expressed concerning the influence of the structure of enamel and dentine on the mechanical behaviour of these mineralised tissues. The possible limitations of previously used tests have been considered in the present work, and alternative testing procedures have been used in efforts to eliminate possible sources of error in mechanical testing. Two alternative tensile testing procedures have been used which indicate that the strength of enamel is approximately four times greater than the previously reported value. In addition an estimation of the modulus of elasticity of enamel in tension is reported, and it has been found by shear testing that enamel is anisotropic with respect to its mechanical properties. The same tests demonstrate that human dentine is less susceptible to the effects of variables in testing procedures which, in the case of enamel are critical. Previously reported tensile strength estimations on dentine have been substantiated by alternative testing procedures. Precise and known dentinal tubule orientations have been obtained in specimens for mechanical testing and the values obtained suggest that dentine also is anisotropic with respect to its mechanical properties. Comparative strength estimations have been made on recently introduced composite restorative materials which indicate that the mechanical properties of these materials are considerably improved in comparison with previously available materials. The properties of the strongest material are very similar to those of enamel and dentine. Preliminary investigations into the possible development of an adhesive restorative material are also described.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available