Evaluation of Shear Bond Strength of Orthodontic Adhesives Containing Zinc Oxide Nanoparticles: An In Vitro Study

Background Orthodontic bonding materials are required to provide adequate adhesion throughout treatment while also permitting safe debonding upon completion. Recently, the incorporation of nanoparticles into composite resins has gained attention due to their antimicrobial properties and their potential to reduce enamel decalcification around orthodontic brackets. However, such modifications may influence the mechanical and physical characteristics of adhesives, particularly the shear bond strength. Limited evidence is available regarding the effect of zinc oxide nanoparticles on the bond strength of orthodontic brackets. Aim This study aimed to evaluate and compare the shear bond strength of orthodontic brackets bonded using an adhesive containing zinc oxide nanoparticles with that of a conventional orthodontic adhesive. Materials and Methods A total of 32 extracted human premolars with intact structure were selected for this in vitro investigation and randomly assigned into two equal groups ( n = 16). Stainless steel brackets (McLaughlin–Bennett–Trevisi (MBT) 0.022″ × 0.028″) were bonded to the buccal surfaces using two different adhesive systems: one incorporated with 1% zinc oxide nanoparticles and the other without nanoparticle addition, serving as the control. After 24 h, shear bond strength was measured using a universal testing machine (UTM). The collected data were statistically analyzed using IBM Statistical Package for Social Sciences version 24, and an independent t -test was applied to determine the significance of differences between groups. Results A statistically significant difference in shear bond strength was observed between the two groups. The experimental group demonstrated a mean value of 2.8 MPa, whereas the control group showed a considerably higher mean value of 16.28 MPa. Conclusion The addition of zinc oxide nanoparticles to orthodontic adhesives has a significant impact on shear bond strength, which may restrict its effectiveness for clinical use.