Long-term nano-mechanical properties of biomodified dentin-resin interface components

Failures of dental composite restorative procedures are largely attributed to the degradation of dentin-resin interface components. Biomodification of dentin using bioactive agents may improve the quality and durability of the dentin-resin bonds. The aim of this study was to nanomechanically assess the reduced modulus of elasticity (Er) and nano-hardness (H) of major components of the dentin-resin interface (hybrid layer, adhesive layer and underlying dentin) biomodified by collagen cross-linkers at 24h, 3 and 6 months following restorative procedure. Demineralized dentin surfaces were biomodified with 5% glutaraldehyde (GD) or 6.5% grape seed extract (GSE) prior to placement of adhesive systems and composite resin. Nano-measurements of the interface components in a fluid cell showed that both agents increased the Er and H of underlying dentin after 3 and 6 months when compared to a control. The mechanical properties of the adhesive and hybrid layers decreased over time. Biomodification of the dentin-resin interface structures using GD and GSE can increase the mechanical properties of the interface over time and may contribute to the long-term quality of adhesive restorations.