Both synthetic and naturally derived crosslinkers have been found to exhibit significant effects in biomodification of dentine via their multiple interactions with the dentine matrix .
A stable matrix network or a durable hybrid layer in dentine bonding could be achieved , where the dentine collagen fibrils show improved biochemical and biomechanical properties and enzymatic biodegradation is reduced .
This aim of this review is to explore the current research related to  crosslinking agents used on dentine .
Effect of proanthocyanidin incorporation into dental adhesive resin on resin-dentine bond strength.
OBJECTIVES This study evaluated the effect of proanthocyanidin ( PA ) incorporation into experimental dental adhesives on resin-dentine bond strength . METHODS Four experimental hydrophilic adhesives containing  different PA concentrations were prepared by combining 50wt% resin comonomer mixtures with 50wt% ethanol . Proanthocyanidin was added to the ethanol-solvated resin to yield three adhesives with PA concentrations of 1.0 , 2.0 and 3.0wt% , respectively . A PA-free adhesive served as the control . Flat dentine surfaces from 40 extracted third molars were etched with 32 % phosphoric acid . The specimens were r and omly assigned to one of the four adhesive groups . Two layers of one of the four experimental adhesives were applied to the etched dentine and light-cured for 20s . Composite build-ups were performed using Filtek Z250 ( 3 M ESPE ) . After storage in distilled water at 37 ° C for 24h , twenty-four bonded teeth were sectioned into 0.9 mm × 0.9 mm beams and stressed to failure under tension for bond strength testing . Bond strength data were evaluated by one-way ANOVA and Tukey 's test ( α=0.05 ) . Interfacial nanoleakage was examined in the remaining teeth using a field-emission scanning electron microscope and analysed using the Chi-square test ( α=0.05 ) . RESULTS No significant difference in bond strength was found amongst PA-free , 1 % and 2 % PA adhesives . However , incorporation of 3 % PA into the adhesive significantly lowered bond strength as demonstrated by a greater number of adhesive failures and more extensive nanoleakage along the bonded interface . CONCLUSION Incorporation of 2 % proanthocyanidin into dental adhesives has no adverse effect on dentine bond strength . CLINICAL SIGNIFICANCE The addition of proanthocyanidin to an experimental adhesive has no adverse effect on the immediate resin-dentine bond strength when the concentration of proanthocyanidin in the adhesive is less than or equal to 2 %
Both synthetic and naturally derived crosslinkers have been found to exhibit significant effects in biomodification of dentine via their multiple interactions with the dentine matrix .
A stable matrix network or a durable hybrid layer in dentine bonding could be achieved , where the dentine collagen fibrils show improved biochemical and biomechanical properties and enzymatic biodegradation is reduced .
This aim of this review is to explore the current research related to  crosslinking agents used on dentine .