Comparative Evaluation of Shear Bond Strength of Orthodontic Brackets using Laser Etching and Two Conventional Etching Techniques: An in vitro Study

Abstract

Introduction: The purpose of this study was to evaluate and compare the shear bond strength between the bracket and acid etched enamel, enamel treated with self-etch primer and laser irradiated enamel and to analyze the interface of the enamel bracket bond. Materials and methods: Around 60 noncarious human premolars were divided randomly into three groups of 20 each and etched using 37% phosphoric acid, self-etch primer and Er:YAG laser. Stainless steel brackets were then bonded using Transbond XT following which all the samples were stored in distilled water at room temperature for 24 hours. Shear bond strength was tested using a chisel edge, mounted on the crosshead of Universal Testing Machine. After debonding, the teeth were examined under 10× magnification with a stereomicroscope and ARI score determined. Shear bond strengths of the three groups were then compared using ANOVA test (multiple comparisons, Tukey’s correction). Comparison of the ARI scores was done using Chi-square test. Result: The acid etched group yielded the highest mean debonding force (13.34 Mpa) followed by self-etch group (12.15 Mpa) and laser etch group (12.10 Mpa). No significant difference was found between the three groups. On comparison of the ARI scores, it was found that the adhesive left on the enamel surface after debonding was significantly higher in the acid etched group than the self-etch group (p = 0.009). There was no significant difference in the ARI scores between the other two groups. Conclusion: These results indicate that the shear bond strength of all the three groups was clinically acceptable with no significant difference between them but more adhesive was left on enamel treated with acid and laser as compared to self-etch primer treated enamel.