In-vitro comparison of shear bond strength of orthodontic brackets bonded with light cured light bond™ and chemical cured rely⋅a⋅bond®

Aim: The aim of this study was to compare the shear bond strength of light cured Light Bond™ and chemical cured Rely⋅a⋅Bond® with light cured Transbond™ XT which was used on routine clinical practice. Material and method: Bond strengths, debonding distances, amount of residual adhesive on tooth after debonding, and scanning electron microscopic images of three teeth which have close values to the average value of each group were examined and compared. In our study, total of 90 bovine lower permanent incisor teeth were used. Bond strengths and residual adhesive indices of three groups which contain 30 teeth were analyzed using the Kruskal –Wallis test. Dunn-Bonferroni test was used as a multiple comparison test in case of Kruskal-Wallis analysis resulted difference. P < 0.05 was considered as statistically significant. Results: The bond strengths in groups Light Bond™, Rely⋅a⋅Bond® and Transbond™ XT were 19,45 MPa, 18,28 MPaand14,73 MPa respectively. Significant differences on the bond strenghts between Light Bond™ and Transbond™ XT were founded. Significant differences on the bond strenghts between Rely⋅a⋅Bond® and Transbond™ XT were observed. There was not any statistically significant difference on the bond strengths between groups Light Bond™ and Rely⋅a⋅Bond®. There was a significiant difference in debonding distances between groups Rely⋅a⋅Bond® and Transbond™ XT. There was not any significant difference in debonding distances between three groups. In the groups Light Bond™, Rely⋅a⋅Bond® and Transbond™ XT, predominant ARI scores were 3,1 and 1 respectively. In the scanning electron microscopic images, frequent and tall resin tags were observed in group Light Bond™. In group Rely⋅a⋅Bond®, heterogen resin tags with various lengths which were taller than group Light Bond™ were viewed. In group Transbond™ XT, resin tags were frequent which were shorter compared with other groups. Conclusion: Light Bond™ had the highest bond strengths values with homogen and deeper resin tags. Elimination of 37% acid application step in Transbond™ XT group has decrased bond strength by reducing the penetration of the adhesive. Rely⋅a⋅Bond® had tallest resin tags and the longest debonding distance which provides more flexibility compared wtih other groups.