Aim: This study was conducted to evaluate the effect of proanthocyanidin-containing natural cross-linkers on the resin-dentin bond strength and dentin matrix stiffness.

Methods: Forty-five specimens were prepared from 9 recently extracted molars for microtensile bond strength(µTBS) testing. Specimens were divided according to the type of extract used for dentin pretreatment into 3 groups(n=15): Control group(CO), Grape seed extract(GSE), Cacao seed extract(CSE). Occlusal enamel of the teeth was removed exposing superficial dentin. The exposed dentin surface was etched using 35%phosphoric acid, then the respective pre-treatment was applied using a microbrush for 1 minute and blot dried, afterwhich the adhesive was applied. Composite was then built onto the pre-treated dentin surface in 2 increments(2mm each) and the teeth were sectioned using an isomet saw into beams(1x1x8mm) and micro-tensile bond strength was evaluated using a universal testing machine. For dentin stiffness evaluation, nine sound molars were used to obtain 45 dentin beams(1x1x6.5mm). Beams were fully demineralized using a 10%phosphoric acid solution and rinsed for 10 minutes with distilled water. Beams were then divided into 3 groups(n=15) and treated with the respective extract for 1 minute. To evaluate the dentin stiffness the beams were subjected to 3-point loading.

Results: µTBS results revealed insignificant difference between the tested groups. Concerning dentin matrix stiffness; grape seed extract recorded significantly higher mean value compared to cacao seed extract and control.

Conclusion: Treating demineralized dentin for 1 minute using grape seed extract improved the stiffness of dentin matrix, but was insufficient to improve the resin-dentin microtensile bond strength.