Effect of dentin biomodification using natural collagen cross-linkers on the durability of the resin-dentin bond and demineralized dentin stiffness.

OBJECTIVE: The purpose of this study was to evaluate the effect of using natural cross-linkers as sumac and curcumin on the durability of the resin-dentin bond and stiffness of demineralized dentin matrix. METHODS: Thirty sound molars were divided into 5 groups: Control (CO), Grape Seed extract (GSE), Cacao seed extract (CSE), Sumac extract (SE) and Curcumin extract (CE). The teeth had their coronal dentin exposed, etched, and pre-treated for 1 min with the extracts. Teeth were then bonded using Single-Bond II adhesive and 4 mm composite was built up on dentin surface. Teeth were sectioned into 1 x 1 x 8mm beams and their micro-tensile bond strength (muTBS) was tested after 24 h and 6 months of water storage. For stiffness testing, 15 teeth were sectioned to obtain dentin beams (1 x 1 x 6.5 mm), the beams were demineralized in 10% phosphoric acid then rinsed and divided into 5 groups. Beams were then immersed in their respective extract solution for 1 min after which they were subjected to a 3- point loading test using a universal testing machine to calculate their modulus of elasticity. RESULTS: After 24 h, no significant difference in muTBS was shown between all groups. After 6 Months, GSE, CE, and SE showed significantly higher muTBS compared to CO (p >/= 0.05). For the modulus of elasticity; only GSE showed a significantly higher modulus compared to other groups. CLINICAL RELEVANCE: The application of grape seed extract, curcumin and sumac extract as dentin pre-treatments appear to be a promising approach to enhance the durability of the resin-dentin bond in a clinically relevant application time.