Effect of Collagen Cross-linkers on Dentine Biomodification and Durability of Resin-dentine Bond: An In vitro Microtensile Bond Strength Study

Introduction: Dental composites, commonly used for restorations, face high failure rates (15%–50%) within 10 years, largely due to dentine’s complex structure. Factors such as hydrophilic monomer use and inadequate collagen infiltration weaken bond strength. This study investigates the effectiveness of the natural cross-linker quercetin, comparing its impact on bond strength to other agents. Materials and Methods: Thirty freshly extracted human molars that met the inclusion and exclusion criteria were collected and stored in 0.1% thymol solution. Teeth were randomly divided into five experimental groups: I – quercetin, II – carbodiimide, III – grape seed extract (GSE), IV– ethanol and V – water wet bonding (control). The enamel surface of the molars was ground to expose mid-coronal dentine. Acid etching with 37% phosphoric acid, rinsing for 45–60 s, and blot drying was done. Thereafter, the respective collagen cross-linking agent was applied for 1 min. A bonding agent was applied and light cured. Incremental nanohybrid light-cured composite build-up (4–6 mm) was done. Resin-dentine sticks of approximately 9.0 mm × 1.0 mm × 1.0 mm were prepared and secured in an acrylic jig. The tensile force was applied using a universal testing machine at a speed of 0.5 mm/min at the tooth–restoration interface. Samples for delayed testing were stored in artificial saliva till testing after 6 months. Microtensile bond strength was calculated as F/A (MPa). Results: Immediate testing showed significantly higher strength values for quercetin, carbodiimide and GSE as compared to ethanol and water wet bonding. There was no significant difference in the strength at 6-month intervals for quercetin, carbodiimide and GSE. Ethanol and control groups showed a statistically significant reduction in the bond strength after 6 months. Conclusion: Biomodification of dentine matrix using various collagen cross-linkers may contribute to long-term resin–dentine bonds.