Effect of Adhesion Promoter on Bond Strength of Reconditioned Brackets – an In vitro Study

Objectives: To compare the shear bond strength of recycled orthodontic metal brackets using an adhesion booster and conventional primer and using the Adhesive Remnant Index (ARI) score to assess the site of debonding.

Materials and Methods: Eighty premolar teeth were randomly divided into 3 groups of 20 teeth each: Group A-New brackets and Transbond XT, Group B-Recycled brackets and Transbond XT, Group C-Recycled brackets and Transbond XT + Enhance LC. Brackets were recycled using sandblaster. Bond strength was tested on a universal testing machine and remnant adhesive on the tooth surface was determined. Kruskal Wallis test and Mann Whitney test were carried out to know the significant difference between the groups. Chi – square test was used to determine significant differences in the ARI (Adhesive Remnant Index) scores.

Results: Highest mean load was recorded in Group A (9.58±1.72 MPa), followed by Group C (8.60±2.05 MPa) and Group B (6.39±1.64 MPa). Chi- square test indicated significant differences (P=.002) in ARI scores. Group A and Group C were associated significantly for score 2 of ARI; Group B for Score 0 of ARI.

Conclusion: The bond strength of recycled orthodontic brackets with Transbond XT was significantly lower when compared to bond strength of recycled brackets with an adhesion booster. After recycling the brackets with sandblaster and using an adhesion booster, the previously debonded brackets gave the bond strength comparable to new brackets with Transbond XT. The ARI data showed statistically significant association between the ARI scores and the groups.