In Vitro Evaluation of the Bond Strength of Metal Brackets Adhered to Different Dental Restorative Materials using Different Orthodontic Adhesives

Background: During orthodontic treatment, teeth with brackets may sometimes be restored with different restorative materials. In this case, the content of the orthodontic adhesive selected for bracket bonding may also be important. Aim: This study compared the bond strength of metal orthodontic brackets adhered to different resin composite and glass ionomer cement (GIC) restoration surfaces with glass ionomer-based and resin-based orthodontic adhesives to determine the best orthodontic adhesive for use in restored teeth. Material and Methods: This study prepared 80 discs. Four material groups of 20 discs were created: reinforced high-viscosity GIC, high-viscosity GIC, flowable bulk-fill resin composite, and nanohybrid resin composite. Specimens in each material group were divided into two subgroups that differed in the orthodontic adhesive used to bond the brackets to the prepared specimens. After 24 hours, the specimens were shear bond strength (SBS) tested at 1 mm/min using a universal tester. Results: The SBS of glass ionomer-based orthodontic adhesive differed significantly between metal brackets adhered to different bases (P < 0.001). The highest SBSs were observed between metal brackets and high-viscosity glass ionomer restorations (6.79 +/- 2.38). The highest SBSs observed with a resin-based orthodontic adhesive were between metal brackets adhered to nanohybrid resin composite restorations (8.84 +/- 2.10; P = 0.030). Conclusions: Glass ionomer-based orthodontic adhesive provided safer bond strength and demineralization prevention when applying metal brackets to teeth with glass ionomer restorations.