Effect of Thermocycling and Surface Treatments on the Durability of Bond Strength of Translucent Zirconia to Resin Cement: An In Vitro Study

Abstract

Background: Achieving a durable bond between translucent zirconia and resin cement remains challenging due to the material's low surface energy and inherent smoothness. Surface treatment is essential for enhancing bond strength, and thermocycling is critical for predicting clinical performance. Objective: This study aimed to investigate the influence of various substrate modifications on zirconia-resin bonding and to assess the impact of artificial aging on bond durability after 5,000 thermocycles. Materials and methods: Seventy-two zirconia blocks were divided into three groups according to surface treatment: selective infiltration etching (SIE), sandblasting, and CoJet. Shear bond strength (SBS) was measured before and after thermocycling using a universal testing machine. SEM analysis was performed on the surface conditions, the debonded interface, and the failure patterns (adhesive, cohesive, or mixed). Data were analyzed using one-way ANOVA with Tukey's post hoc test and two-way ANOVA. Results: Before thermocycling, the sandblasted and SIE groups showed higher SBS compared to the CoJet group. After thermocycling, the sandblasted group showed a 40% reduction in SBS, the CoJet group a 22% reduction, and the SIE group showed the least (9%). Adhesive failure was dominant in the sandblasted and CoJet groups, while the SIE group had more cohesive failures. Conclusion: The SIE surface treatment demonstrated the highest bond strength and the greatest resistance to thermocycling, suggesting its potential as a reliable surface modification to enhance the durability of zirconia-resin bonding.