An In Vitro Study to Compare the Shear Bond Strength of Orthodontic Brackets Bonded to Permanent Teeth by Using Conventional Acid-Etching and Self-Etching Primers

Objectives: The objective of the present study was to evaluate and compare the bond strength of orthodontic brackets bonded to permanent teeth with a conventional acid-etching and self-etching primer systems. Also, the study aims to evaluate the mode of bond failure after debonding the brackets. Materials and Methods: It was an experimental study. Fifty extracted permanent premolars were collected, checked, and cleaned. Teeth were split equally into two groups, group A and B. Orthodontic brackets were bonded using conventional acid-etching and self-etching primer systems for group A and B, respectively. Shear bond strength (SBS) was measured with a universal testing machine, and the mode of bracket-adhesive failure was determined by using adhesive remnant index (ARI). Data were analyzed with a statistical software. Independent sample t-test was used to compare the SBS and Mann–Whitney U test was used to assess whether there is a significant difference of ARI score between the groups. Results: Although the SBS with self-etching primer was within clinically acceptable range, the overall mean SBS for group A (14.71 MPa) was significantly greater than group B (9.24 MPa) (P = 0.024). There was no significant difference in ARI scores between conventional acid-etching and self-etching groups (P = 0.801). Conclusion: The SBS of the conventional acid-etching was significantly higher than the self-etching primer. The SBS of self-etch was within the acceptable range to withstand the forces of mastication. The majority of the brackets recorded ARI score of 1 indicating a cohesive failure with no significant difference between acid-etch and self-etch groups.