Keynote Address: Is the Dentin Enamel Junction Important to Durability of the Bonded Interface?

Abstract Body: Durability is an important quality of dental materials and their bonds to tooth structure. While the dentin enamel junction (DEJ) is largely credited with arresting cracks and the fracture resistance of teeth, its contribution to adhesive bonds has been unclear. This presentation will discuss the durability of adhesive bonds involving the DEJ according to results of evaluations by static and cyclic loading, and through a comparison to adhesive bonds involving enamel only. The findings indicate that although the DEJ is important to bond strength, bonds involving the DEJ are less resistant to fatigue failure than those to decussated enamel. The DEJ deters cracks from extending into the dentin, but it does not prevent fatigue failures. These results suggest that enamel rod decussation is more important to the durability of bonds to tooth structure than the DEJ. Capitalizing on that finding, new strategies for designing and developing restorative materials are introduced.