Ion-releasing Resin Composites as Clear Aligner Attachments: Comparison of Caries-inhibition Effect and Shear Bond Strength to Ename

Objectives: To evaluate mineral loss and lesion depth of enamel adjacent to different ion-releasing resin composites in conjunction with artificial caries induction, and to evaluate shear bond strength to enamel. Methods: Three ion-releasing resin composites (ACTIVA™ BioACTIVE-RESTORATIVE™, BEAUTIFIL Injectable XSL and Cention® N) with or without adhesive system were investigated in comparison with a conventional resin composite (Filtek™ Z350 XT). Effect of Caries Inhibition in Adjacent Enamel – 36 human premolars with cylindrical cavities and filled with restorative materials underwent 14 days of artificial caries induction and were sectioned into two cross-sectional specimens (n=12). Mineral loss and lesion depth were measured at 10, 260, 510, and 760 μm from the tooth-restoration interface and analyzed using repeated measures ANOVA and pairwise comparison for within group comparisons (p<0.05) and One-way ANOVA with Tukey’s post hoc test for comparisons among groups (p<0.05). Shear bond strength test – 108 human premolars were embedded in self-curing acrylic resin. A polyethylene tube was placed on each surface and filled with restorative materials. Each group was divided into 2 subgroups (n=9) whether the specimens were thermocycled or not. Shear bond strength was tested with the Instron® 5566 universal testing machine. Failure analysis was conducted using a stereomicroscope. Shear bond strength was analyzed using two-way ANOVA and Tukey’s multiple comparison test (p<0.05). Results: At 14 days post-caries simulation, ACTIVA™ BioACTIVE-RESTORATIVE™ and Cention® N with and without adhesive demonstrated an ability to inhibit caries formation at 10 μm from the restoration-enamel interface. Shear bond strength to enamel of Cention® N with adhesive had the highest values for both non-thermocycling (21.68±1.86 MPa) and thermocycling (21.17±2.4 MPa) condition, being significantly higher than other groups except for the conventional resin composite (20.3±1.85 MPa for non-thermocycling and 19.16±2.29) MPa for thermocycling condition.\ Conclusions: The use of Cention® N with adhesive provides the optimal combination of shear bond strength and caries inhibition effect, which is potentially a superior candidate for clear aligner attachments.