Shear bond strength of orthodontic brackets after adding silver nanoparticles to a nano-bond adhesive at different thermal cycles and cyclic loading- An in vitro study

OBJECTIVE: To evaluate the effects of silver nano particles (AgNPs) added on Nano-Bond adhesive system (NBA) and its effect on shear bond strength (SBS) of orthodontic brackets attached to enamel at different thermal cycles and cyclic loading. MATERIALS AND METHODS: Forty extracted premolar teeth for orthodontic reasons were divided randomly into two main groups (20 teeth in each group). Group A: the brackets were bonded by NBA without additives. Group B: the brackets were bonded by NBA containing AgNPs with concentration 0.05%. Every group was further subdivided into 4 subgroups according to teeth subjected or not subjected to thermocycling and cyclic loading. SBS was tested using Lloyd universal testing machine. One-way analysis of variance (ANOVA) was used for testing the significance between the means of tested groups. The SBS increased in Group B with AgNPs compared to Group A in all the conditions tested. Group A1 and B1 with zero thermal cycling and cyclic loading exhibited highest mean SBS. CONCLUSIONS: These results indicate addition of AgNPs significantly increased the shear bond strength of Nano-Bond adhesive system.