The effect of antimicrobial photodynamic therapy on shear bond strength of orthodontic bracket: An in vitro study

Objectives: The aim of this study was to evaluate the effect of antimicrobial photodynamic therapy (aPDT) with methylene blue (MB) and indocyanine green (ICG) on bond strength of orthodontic brackets to enamel. Materials and methods: A total of 45 non-carious and sound human premolar teeth were used in this study. All teeth were examined under a stereomicroscope at x10 magnification. The samples were divided to 3 groups including no treatment (control group), aPDT with MB and 660 nm diode laser and aPDT with ICG and 808 nm diode laser. After aPDT procedure, orthodontic brackets were bonded to enamel surfaces. Then, the samples were thermocycled for 5000 cycles between 5 degrees and 55 degrees C in water bath. The brackets were then debonded using a universal testing machine. The adhesive remnant index (ARI) score and SEM microscope evaluation were assessed. One-way analysis of variance (ANOVA) with Post-hoc test were used to compare the SBS values among groups. Results: The highest SBS mean value was presented in group 1 (control) (31.98 +/- 6.36). Whereas, the lowest SBS mean value was observed in group 3 (aPDT with ICG) (24.11 +/- 5.78). There were significant differences in SBS values between control and aPDT groups (P < 0.05). Some superficial porosity and irregularity was presented following aPDT on surface of enamel when examined by scanning electron microscope. The mode of failure was mostly score 0 and score 1 in all groups. Conclusion: MB and ICG mediated antimicrobial photodynamic therapy both reduced the bond strength of orthodontic brackets compared to control group.

Automated summary

This study evaluated the effect of antimicrobial photodynamic therapy with methylene blue and indocyanine green on the bond strength of orthodontic brackets to enamel. The results showed that this therapy reduced the bond strength of orthodontic brackets compared to the control group.