Comparison of shear bond strength of rebonded stainless steel brackets with three different enamel surface conditioning methods

Abstract

Background: During the orthodontic bonding process, the need for repositioning or rebonding of
orthodontic brackets on the enamel surface occurs frequently. The aim of this study is to compare
the shear bond strength (SBS) in rebonding orthodontic stainless steel brackets with three different
methods of enamel surface conditioning methods.
Materials and Methods: In this in vitro study, 80 human premolars that were extracted for
orthodontic purposes were randomly divided into four groups and underwent orthodontic bonding
procedure (N = 20). Except for the control group, three other groups underwent debonding and
rebonding process in which after removing the remaining adhesive with tungsten‑carbide bur,
enamel surface conditioned by three different methods including re‑etching with phosphoric acid,
sandblasting + acid etching, and Erbium‑doped Yttrium–Aluminum–Garnet laser. Then, the SBS of
the bracket to the enamel surface was compared between different groups. Scanning Electron
microscopy images were also obtained from a number of samples. Statistical analysis was performed
by Kruskal–Wallis and Mann–Whitney tests.
Results: The highest SBS was observed in the primary bond (control group) with an average of
29,440 MPa. There was a significant difference between the studied groups (P < 0.001) and only
the group that was re‑etched with phosphoric acid had no significant difference with the control
group (P = 0.708) ∝ =0.05.
Conclusion: Rebonding of brackets using phosphoric acid for reconditioning of the enamel surface
creates bond strength comparable to the primary bond. Other groups had significantly lower SBS
than the control group.
Key Words: Dental air abrasion, dental bonding, dental debonding, orthodontic bracket,shear strength