Figure 3. Representative results for the "dehydrated/rehydrated/dehydrated" tests (N = 3) for whisky expressed in terms of the fracture toughness R-curve behavior. These experiments give a clear indication of how the toughness dropped when dehydrated dentin was exposed to water (HBSS), and that the fracture toughness of dentin was significantly higher in whisky. However, they also provide clear evidence that the effect was completely reversible.