Abstract:
Background: Clear aligner therapy has gained widespread popularity as an aesthetically favorable and patient-comfort alternative to traditional fixed orthodontic appliances. The attachments used in conjunction with aligners must provide adequate bond strength to withstand the repetitive forces of tray insertion and removal, while simultaneously protecting the enamel from demineralization. Ion-releasing resin composites, which release fluoride and other beneficial ions, offer the potential to enhance both the mechanical stability of the attachments and the caries inhibition effect of adjacent enamel.Purpose: 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: Four ion-releasing resin composites (Activa™ BioACTIVE-RESTORATIVE™, Beautifil Injectable X SL , Cention N and Predicta Bioactive Bulk Restorative) with and without adhesive system were investigated. Effect of Caries Inhibition in Adjacent Enamel 48 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 tooth-restoration interface. 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) for 10,000 cycles of thermocycling. Shear bond strength was tested with the Instron® 5566 universal testing machine. Failure analysis was conducted using a stereomicroscope. Results: At 14 days post-caries simulation, Activa 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 thermocycling and non-thermocycling condition, being significantly higher than other groups except for the conventional resin composite. 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. Keywords: clear aligner attachment, caries inhibition, ion-releasing resin composite, shear bond strength