Changqi Xu1, Yong Wang. 1. University of Missouri-Kansas City, School of Dentistry, Kansas City, MO 64108, USA.
Abstract
PURPOSE: The biodegradation of exposed dentin collagen within the adhesive/dentin (a/d) interface is one of the main reasons for composite restoration failures and seriously affects the durability of dental restorations. In the present study, the objective was to investigate whether the inclusion of the cross-linking reagent (glutaraldehyde, GA) in the adhesive would increase collagen biodegradation resistance within the a/d interface. MATERIALS AND METHODS: The model adhesive consisted of ~60 % monomers (HEMA/bis-GMA, 45/55 wt/wt) and ~ 40 % ethanol as a solvent. 5% GA was added to the above formulation. After the dentin surfaces were etched for 15 s with 35% phosphoric acid, rinsed with water and blotted dry, adhesives both with and without GA were applied and polymerized by visible light for 20 s. These a/d specimens were immersed in the biodegradation solution (prepared by adding 160 mg collagenase in 1 liter of TESCA buffer solution) for up to 30 days after proceeding with the sectioning/fracture to expose the a/d interfaces. The specimens were analyzed using SEM and micro-Raman spectroscopy. RESULTS: SEM results indicated that for the adhesive without GA, there were many voids and a loss of collagen fibrils in the a/d interface after being challenged by the biodegradation solution. The Raman spectra collected from the interface showed that the amide I of collagen at 1667 cm-1 obviously decreased, indicating a removal of collagen fibrils during the degradation process. For the adhesive containing GA, the collagen fibrils within the interface did not degrade at all, which was also confirmed by the Raman results. CONCLUSION: The results corroborate the previous findings that by using the current adhesive system and wet bonding, the collagen fibrils in the a/d interface are largely unprotected and easily undergo biodegradation. Directly including cross-linking agents in the adhesive could protect collagen fibrils from degradation in situ within the a/d interface.
PURPOSE: The biodegradation of exposed dentin collagen within the adhesive/dentin (a/d) interface is one of the main reasons for composite restoration failures and seriously affects the durability of dental restorations. In the present study, the objective was to investigate whether the inclusion of the cross-linking reagent (glutaraldehyde, GA) in the adhesive would increase collagen biodegradation resistance within the a/d interface. MATERIALS AND METHODS: The model adhesive consisted of ~60 % monomers (HEMA/bis-GMA, 45/55 wt/wt) and ~ 40 % ethanol as a solvent. 5% GA was added to the above formulation. After the dentin surfaces were etched for 15 s with 35% phosphoric acid, rinsed with water and blotted dry, adhesives both with and without GA were applied and polymerized by visible light for 20 s. These a/d specimens were immersed in the biodegradation solution (prepared by adding 160 mg collagenase in 1 liter of TESCA buffer solution) for up to 30 days after proceeding with the sectioning/fracture to expose the a/d interfaces. The specimens were analyzed using SEM and micro-Raman spectroscopy. RESULTS: SEM results indicated that for the adhesive without GA, there were many voids and a loss of collagen fibrils in the a/d interface after being challenged by the biodegradation solution. The Raman spectra collected from the interface showed that the amide I of collagen at 1667 cm-1 obviously decreased, indicating a removal of collagen fibrils during the degradation process. For the adhesive containing GA, the collagen fibrils within the interface did not degrade at all, which was also confirmed by the Raman results. CONCLUSION: The results corroborate the previous findings that by using the current adhesive system and wet bonding, the collagen fibrils in the a/d interface are largely unprotected and easily undergo biodegradation. Directly including cross-linking agents in the adhesive could protect collagen fibrils from degradation in situ within the a/d interface.
Authors: Vadim Elagin; Daria Kuznetsova; Ekaterina Grebenik; Denis A Zolotov; Leonid Istranov; Tatiana Zharikova; Elena Istranova; Anastasia Polozova; Dmitry Reunov; Alexandr Kurkov; Anatoly Shekhter; Elvira R Gafarova; Victor Asadchikov; Sergey M Borisov; Ruslan I Dmitriev; Elena Zagaynova; Peter Timashev Journal: Front Bioeng Biotechnol Date: 2020-02-19
Authors: Tanveer Ahmed Shaik; Alba Alfonso-Garcia; Martin Richter; Florian Korinth; Christoph Krafft; Laura Marcu; Jürgen Popp Journal: Molecules Date: 2020-08-25 Impact factor: 4.411