The role of collagen cross-linkers in the stability of the adhesive interface

The subject of the thesis is the stability of the adhesive interface created at the level of the dental substrate. The connection between polymerized adhesives and the remaining mineralized dentin occurs through the collagen fibrils extending from the underlying mineralized matrix towards the hybrid layer. The collagen fibrils contain bound, non-collagenous proteins such as growth factors and matrix proteases. These proteases play an important role during dentin maturation, but they become trapped and inactive after the collagen matrix mineralized. However, during adhesive procedures, the enzymes of the collagen matrix are exposed and activated, irrespective of the E&R or SE procedure employed, resulting in the progressive degradation of the collagen fibril anchoring the restorative material to tooth structure. This leads to solubilization of collagen and loss of retention of the adhesive restoration. Recent studies supported the use of protein cross-linking agents during bonding procedures to prevent dentin collagen degradation caused by endogenous enzymes to improve bond durability. Acrolein (ACR),1-ethyl-3- (3-dimethylaminopropyl) carbodiimide (EDC) and dicyclohexylcarbodiimide (DDC) are compounds claimed to be potent cross-linkers. The present series of studies aimed at investigating the effect of various collagen crosslinkers on dentin protease activity and their effect on bond-strength to the dentinal substrate. Thus, selected collagen cross-linkers were tested to determine their effect on MPa values on coronal and radicular dentin, the marginal infiltration at the resin dentin interfaces, the presence of endogenous enzymatic activity after treatment and the localization of the gelatinase activity on dentin. Additionally, the effect of the crosslinkers and the effect of treatment period (duration) on the degradation of collagen matrices were examined. The results obtained suggest that collagen crosslinkers can inactivate e the collagen degradation through the inactivation of dentin proteases. However, in vivo studies are essential to better understand the feasibility of the tested molecules as dentin conditioning.