Resin-based composite (RBC) restorations are widely used in clinical dentistry due to their esthetic appeal and biocompatibility. However, their long-term success depends heavily on the stability of the resin-dentin bond interface. This study investigated the effects of prolonged water storage and thermocycling on the microtensile bond strength (mTBS) of RBC restorations bonded using different adhesive systems.
Thirty-six human third molars were sectioned to expose flat dentin surfaces and randomly assigned to three groups based on adhesive type: (1) etch-and-rinse (Clearfil SE Bond), (2) self-etch (Clearfil S3), and (3) universal adhesive (SingleBond Universal). After bonding, nanohybrid composites (Filtek Z350 XT) were placed and light-cured. Specimens were initially tested for mTBS after 24 hours of water storage (baseline). Remaining specimens were then divided into two subgroups: one stored in distilled water at 37°C for 6 months, and another subjected to 5,000 cycles of thermocycling (5°C to 55°C). After each aging protocol, mTBS testing was repeated.
Results showed a significant decline in bond strength over time. The etch-and-rinse group maintained the highest mTBS values after aging: 58.7 ± 6.3 MPa (water storage) and 54.1 ± 5.9 MPa (thermocycling), both significantly higher than baseline (p < 0.01). The self-etch group exhibited moderate degradation: 49.2 ± 5.7 MPa (water) and 45.3 ± 6.1 MPa (thermocycling). The universal adhesive group showed the greatest reduction: 41.5 ± 7.2 MPa (water) and 38.9 ± 6.8 MPa (thermocycling), with statistically significant differences from all other groups (p < 0.05). Failure mode analysis revealed that aging increased the proportion of adhesive failures across all groups. In the etch-and-rinse group, mixed failure remained dominant even after aging, suggesting stable hybrid layer integrity. In contrast, the self-etch and universal groups displayed a marked increase in interfacial separation, indicating hydrolytic degradation of the adhesive layer. Scanning electron microscopy confirmed visible gaps and debonding at the interface following thermocycling. These findings highlight that while all adhesive systems degrade over time, the etch-and-rinse approach provides superior resistance to environmental challenges.POLR3GL Antibody custom synthesis The presence of a well-defined hybrid layer, formed by deep penetration of resin into demineralized dentin tubules, contributes to greater durability.CHRNA7 Antibody Purity Thermocycling accelerates degradation by inducing thermal stress and promoting fluid infiltration into the interface.PMID:35222844 The universal adhesive, despite its versatility, may be more susceptible to hydrolysis due to its high content of hydrophilic monomers.
Clinically, these results emphasize the importance of selecting adhesive systems with proven long-term performance, particularly in load-bearing or posterior teeth. While simplified protocols offer convenience, they may compromise longevity. Future research should explore the use of hydrophobic resins and cross-linking agents to enhance interface stability.
Conclusion: Prolonged water storage and thermocycling significantly reduce the microtensile bond strength of resin-based composite restorations. Etch-and-rinse adhesives demonstrate superior long-term durability compared to self-etch and universal systems. Clinicians should consider the expected service life when selecting bonding materials, prioritizing robust, well-documented protocols for optimal restoration longevity.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com