Figure 7.

A schematic description of crack growth through a decussated zone in enamel. Extension through prism decussation results in a highly tortuous path with multiple deflections. Arrest of cracks in enamel usually occurs while traversing from a less oblique prism orientation (indicated by the highlighted area), also known as the parazone (P) to a more oblique orientation, also known as the diazone (D). The crack traverses through a bundle of prisms along the interprismatic boundary and may undergo bifurcation in the search for a more energetically favorable path.