Effects of phosphoric acid and glutaraldehyde-HEMA on dentin collagen

The purpose of this study was to evaluate the effects of phosphoric acid (P A) and a proprietary glutaraldehyde-HEMA aqueous solution (Gluma Desensitiz er. GD) on dentin collagen. Specimens of demineralized bovine dentin collag en were treated with either 37% or 50% PA for I or 5 min. An additional set of specimens was treated with 37% PA for I min followed by GD for I min. A ll specimens were washed with distilled water, lyophilized, reduced with st andardized (NaBH4)-H-3, hydrolyzed with 6 M HCl and subjected to amino acid and cross-link analyses. The results demonstrated that the treatment of de mineralized dentin with PA under the conditions tested did not significantl y alter the collagen cross-links. The GD-treated samples showed reduction o f free lysine (Lys) and hydroxylysine (Hyl) residues, as well as a decrease in the levels of collagen reducible cross-links. In addition, unidentified reducible compounds were detected by high-performance liquid chromatograph y (HPLC) analysis. These compounds may be derived from cross-links formed b etween GD-derived aldehyde and Lys/Hyl of collagen. The findings indicate t hat PA treatment does not significantly affect dentin collagen amino acid a nd cross-link composition, and that GD treatment affects dentin collagen am ino acid and cross-link composition.