The effect of transient proanthocyanidins preconditioning on the cross-linking and mechanical properties of demineralized dentin.

Proanthocyanidin-based preconditioners were prepared by adding powdered proanthocyanidins-rich grape seed extract to various solvents at different concentrations. Demineralized dentin specimens were preconditioned for 20, 30, 60 or 120 s, followed by the evaluation of their cross-linking degree, mechanical properties and micromorphology. The cross-linking degree of the demineralized dentin collagen exhibited concentration- and time- dependent increase after preconditioning treatment, irrespective of the preconditioner and the solvent. When treated for the same exposure time, specimens after 15% proanthocyanidins preconditioning resulted in the highest mean ultimate tensile strength compared with all the other groups tested. Five percent glutaraldehyde control group produced the highest cross-linking degree, but the ultimate tensile strength was lower than that of 15% proanthocyanidins group. The field emission scanning electron microscopy confirmed that the demineralized dentin collagen was in a homogeneous and regular arrangement after preconditioning and maintained expanding, regardless of the surface moisture conditions.