Date of Award

8-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Joseph, Paul F

Committee Member

Thompson , Lonny L

Committee Member

Li , Gang

Abstract

The human tooth is an amazing structure that is worthy of detailed research and analysis. For over half a century, various tests have been conducted to acquire more information about the structural and material properties of dentin, enamel, and the dentin-enamel junction. Unfortunately, variations still exist in the experimental results, even in the most recently collected data. The primary focus of the majority of material property testing on human teeth has been hardness testing utilizing indentation and nanoindentation analysis. However, several limitations still exist with the indentation technique. Thus, the moirŽ fringe analysis method, specifically microscopic moirŽ interferometry, has been introduced as a viable alternative testing method for the analysis of biological materials.
Microscopic moirŽ interferometry is a real-time, full-field deformation analysis technique that allows for in-depth investigation of the mechanics and structures of materials at a microscopic level. In addition, the use of a compact, four beam immersion interferometer allows for near simultaneous analysis of a specimen in both the U and V displacement fields. A modified microscopic moirŽ interferometry system has been developed which expands on the concepts of both moirŽ interferometry and standard microscopic moirŽ interferometry. This modified system was developed specifically for the specialized minute deformation analysis of biological materials. A sensitivity of 4.8 fringes/µm of displacement has been attained using the modified system while increasing the spatial resolution with the capability of analyzing fringe patterns as small as 22 µm in width. This significant increase is a result of the in-depth analysis, modification, and enhancement of nearly every component in the microscopic moirŽ interferometry system.
Finally, a system validation test was conducted in which two of the elastic constants of human dentin were experimentally determined, specifically the elastic modulus and Poisson's ratio. The results obtained in the test procedure were within the acceptable limits of the previously published data. Therefore, it has been demonstrated that the modified microscopic moirŽ interferometry system possesses the capability of directly determining the mechanical properties of microscopic biological specimens in a timely and accurate manner.

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