The structures of bones and teeth are both hierarchical and graded, spanning length scales from nanometers to centimeters. Much is known about the relations between structure and function at the macroscopic level, and to some extent at the nanometer level with the advent of the nanoindenter and the atomic force microscope. Here we focus on the meso-scale. The structures at this level differentiate between different members of the bone family of materials and hence how they are adapted to their specific functions. They are thus of particular interest. An instrument developed as part of our current NIH funded research, that integrates digital holography (DH) and electronic speckle pattern interferometry (ESPI), will be used. This DH&ESPI instrument is capable of accurately mapping under water the visco-elastic responses of whole teeth when subjected to forces resembling those in mastication. Furthermore, it can accurately and precisely measure strain and then deduce elastic moduli of small cubes of bone or tooth over areas of 100xl000 microns or less. Here it is proposed to use this instrument to systematically map the deformational changes that occur when whole teeth of different types are subjected to compressive forces, and to map the variations in elastic moduli on the internal surfaces of teeth (in particular the soft zone beneath the DEJ) and bone (in particular osteonal bone). This body of knowledge will provide new insights into the material design features of bones and teeth. It will constitute an important basis for improving the functioning of dental materials and bone replacement parts by allowing them to be designed such that they respond mechanically in a manner similar to the original tissue.
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