The Influence of Er:YAG Laser Conditioning versus Self-Etching Adhesives with Acid Etching on the Shear Bond Strength of Orthodontic Brackets

Abstract

The aim of this study was to compare the shear bond strength (SBS) of orthodontic brackets after acid etching, laser ablation, self-etching primer application, and combined treatments. One hundred defect-free premolars were randomly assigned to five groups. The teeth received the following treatments: group 1: phosphoric acid + Transbond XT primer; group 2: Transbond Plus Self-Etching Primer (TPSEP); group 3: Er:YAG laser ablation + Transbond XT primer; group 4: Er:YAG laser ablation + phosphoric acid + Transbond XT primer; and group 5: Er:YAG laser ablation + TPSEP. Transbond XT Adhesive Paste was used in all groups for bracket bonding. Samples were stored in deionized water at 37 degrees C for 24 h. The shear debonding test was performed at a crosshead speed of 5 mm/min. Failed brackets were examined by a stereomicroscope at 16 x magnification to determine the bond failure interface using a modified adhesive remnant index (ARI). SBS values were compared using one-way analysis of variance (ANOVA). The Kruskal-Wallis test was used for ARI scores and pairwise comparisons were done using the Mann-Whitney U test with Bonferroni correction. Mean SBS values (MPa) and standard deviations for the groups were: group 1, 13.18 +/- 3.45; group 2, 13.52 +/- 4.38; group 3, 10.33 +/- 4.74; group 4, 13.00 +/- 3.47; and group 5, 12.46 +/- 6.31. No significant differences were observed in the SBS of all the groups evaluated, but there was a significant difference in ARI scores, with group 3 showing higher ARI scores than groups 1 and 4. Er:YAG laser ablation and self-etching primer application showed similar SBS values as conventional acidetching for bonding brackets.