Analysis of Enamel Wear Against Ceramic Restorations

1. To characterize the microstructure (fracture toughness, particle size of ceramic, and inter-particle spacing) of three ceramic materials 2. To test the hypothesis that lower fracture toughness of glass and/or crystal phase in ceramics reduce wear damage of enamel. 3. To test the hypothesis that smaller sized crystals reduce wear damage of enamel. 4. To test the hypothesis that larger inter-particle spacing reduces wear damage of enamel. 5. To test the hypothesis that equivalent wear patterns exist in all directions between enamel versus enamel and ceramic versus enamel. 6. To test the hypothesis that bite force does not correlate with wear rates. 7. To test the hypothesis that salivary flow does not correlate with wear rates. 8. To test the hypothesis that a greater amount of wear is not associated with a loss in vertical dimension of occlusion. 9. To test the hypothesis that a greater amount of wear does not correlate with secondary cementum deposition as part of the passive eruption process. 10. To test the hypothesis that maximum wear occurs early and wear rates level off within the first two years. 11. To test the hypothesis that in vitro wear analysis does not correlate with in vivo wear measurements