Conditioner’S Influencing Glass Ionomer–Dentin Bond: Varied Thermocycling Conditions

Aim or purpose: This study evaluated the effect of different surface conditioning protocols on the bond strength of high-viscosity glass ionomer cement to primary dentin under various thermocycling conditions. Materials and methods: The study protocol was approved by the institutional ethics committee (Approval No.2024/05-34), and 108 extracted primary teeth meeting the inclusion criteria were used. Specimens were randomly assigned to four groups according to the number of thermocycles (control; 1,000; 5,000; and 10,000). Each group was further divided into three subgroups based on the surface conditioning protocol: no conditioning, conditioning with the liquid of glass ionomer cement, and conditioning with polyacrylic acid. Bond strength was measured using a shear bond test, and the fracture types obtained were examined using a stereomicroscope. Data were analyzed using the Shapiro–Wilk test, robust ANOVA test, and Bonferroni test (p<0.05). Results: The bond strength significantly decreased statistically in thermal cycling processes, regardless of surface conditioning protocols (p<0.001). Independent of thermocycling, surface conditioning protocols (p=0.941) and the interaction effect between thermocycling and surface conditioning (p=0.617) did not significantly affect bond strength. Moreover, there was no significant correlation between fracture types and the study groups (p=0.999). Conclusions: Surface conditioning did not improve the bond strength of high-viscosity glass ionomer cement to primary dentin, while thermocycling had a detrimental effect. These findings highlight the need for alternative conditioning strategies to enhance long-term performance.