Do conventional and new-generation multiple ultrasonic applications change the shear bond strength of metal brackets?

Abstract

Background: The purpose of this study was to compare orthodontic braces' shear bond strength (SBS) before and after conventional and new-generation multiple ultrasonic instrumentations (UIs). Materials and Methods: One hundred and seventy-five extracted human premolars were bracketed and embedded in acrylic molds. Teeth were separated into 7 groups; each group consisted of 25 teeth. All samples were thermocycled 500 times and control group was randomly selected. To the rest of the teeth, UI and vector ultrasonic instrumentation (VUI) were performed, UI1 and VUI1 were separated. Following the second thermocycling, UI and VUI; UI2 and VUI2, and after the third thermocycling, UI and VUI the UI3 and VUI3 were separated. Results: The decreases in the mean SBS of the UI3 and VUI3 were found to be statistically significant compared to the control group's means. There were no statistically significant differences between neither the means of the control group and UI1, UI2, VUI1, VUI2; nor the means of the VUI1-UI1; VUI2-UI2; VUI3-UI3. There was no statistically significant difference among the means of the UI1-UI2-UI3. On the other hand, the VUI3 was found to have the least statistically significant SBS among VUI groups. Conclusions: Our results revealed that multiple UI and VUI applications both reduce the SBS of brackets. Although the reduction with VUI was found to be more than UI, there was no statistically significant difference between the two instrumentations. Both procedures can be used with caution as a multiple cleaning aid for patients undergoing fixed orthodontic treatment.