21 May 2022
31 May 2022
This study aimed to investigate the effect of Er:YAG laser treatment of enamel and bracket base on shear bond strength (SBS) and failure mode of orthodontic brackets to primary molars. Sixty extracted primary molars were collected and randomly assigned into four groups of 15, as follows: Group 1 (Control): conventional acid etching + intact brackets, Group 2: conventional acid etching + laser treated brackets, Group 3: Er.YAG laser etching and conventional acid etching + intact brackets, and Group 4: Er.YAG laser etching and conventional acid etching + laser treated brackets. The Er:YAG laser (2940 nm) was used at settings of 150 mJ, 10 Hz, and 10 seconds for enamel conditioning and 250 mJ, 10 Hz and 10 seconds for bracket treatment. Metal brackets were bonded to teeth with a light-cured composite. After 24 hours’ storage in water, SBS was tested in an Instron machine and the adhesive remnant index was determined. There was a significant difference in SBS between the four groups (P=0.001). Tukey test revealed that the bond strength in group 2 was significantly lower than that of group 3 (P=0.004) and group 4 (P=0.003), whereas other comparisons were not significant (P>0.05). No significant difference was found in ARI scores among the groups (P=0.43). Er:YAG laser etching followed by conventional acid etching was a suitable technique to enhance bracket bond strength to primary enamel. However, laser treatment of new orthodontic brackets had a deleterious effect on bond strength and is not recommended.