The purpose of the study was to evaluate the effect of two collagen cross-linking agents, glutaraldehyde and grape seed extract (GSE), on the modulus of elasticity of demineralized dentin, when used at different concentrations and exposure times. Type I collagen provides tissues and organs with tensile strength, form, and cohesiveness. It is thought that increasing the strength of the dentin matrix using cross-linking agents might improve both the strength and the durability of resin-dentin bonds.Materials and Methods:
Sound extracted molar teeth were ground flat and the teeth were sectioned into 0.5-mm beams and trimmed with a bur to create rectangular blocks of dentin. These were etched with 10% phosphoric acid for 5 hours to cause complete tissue demineralization. They were then treated with 2.5%, 5%, or 25% glutaraldehyde (Fisher Biotech, Fair Lawn, NJ) and 0.65% or 6.5% grape seed extract Mega-Natural (Polyphenolics, Madera, CA). The specimens were immersed in water for baseline measurements and then in their respective solutions for 10 minutes, 30 minutes, 1 hour, 2 hours, and 4 hours of cumulative exposure. Modulus of elasticity was measured using a three-point bend method. A total of 10 to 12 specimens were evaluated per group.Results:
The mean baseline modulus of elasticity (E) values varied between 4.8 and 6.2 MPa in water. After 4 hours of treatment, the values increased up to 34.9 and 242.5 MPa, depending on treatment time and cross-linking agent. The 25% glutaraldehyde resulted in a significantly more rapid rise in E after 10 minutes than 2.5% and 5%, and the use of 0.65% and 6.5% GSE resulted in a statistically significant increase in the E of demineralized dentin following each time tested, with 6.5% GSE being the highest. A statistically significant interaction was observed between the factors studied (treatment and time).Conclusions:
Demineralized dentin stiffness is affected by the use of glutaraldehyde and grape seed extract collagen cross-linking agents. The changes to the dentin matrix after treatment with the cross-linkers were both concentration and time dependent.