Seyyed Amir Hossein Mirhashemi
Mohammad Sadegh Ahmad Akhundi
Saeed Mehdi Pour Ganji
Mehdi Allahdadi
Mohammad Norouzian
Nasim Chiniforush

Abstract Introduction: In recent decades zirconium oxide has been introduced in the field of dentistry as a high-strength ceramic. Unlike its mechanical advantages, however, due to its inert chemical properties, it bonds poorly to other substrates, so improving bonding strength to an adhesive material is necessary.Methods: In this experimental study, ۷۰ ceramic zirconia blocks were prepared and distributed randomly among ۷ groups. Then the shear bond strengths were determined and the samples were examined by a scanning electron microscope (SEM). Statistical analysis was performed by one-way ANOVA and multiple Tukey comparisons.Results: One-way analysis of variance (ANOVA) showed that laser irradiation distance has a significant effect on orthodontics brackets bond strength to zirconia-ceramics. Based on the Tukey post hoc test, each group was compared with other groups and the contact mode and ۲ mm distance groups showed significantly higher bond strength than other groups (P-value <۰.۰۵).Conclusion: Orthodontic bracket bond strength to zirconia-ceramics will be reduced by increasing Er: YAG laser irradiation distance from samples. The highest bond strength will be achieved when the laser irradiation distance is ۲ mm or when the laser beam is in contact with samples. Keywords: Orthodontic bracket bond strength Zirconia surface Laser radiation distance Er YAG Laser