Little is known about the performance of Transbond™ Plus Self-Etching Primer (TPSEP), especially when used with Adhesive Precoated Brackets™ (APC 1 and APC 2). The aim of this study was to compare the shear bond and rebond strengths and failure sites of APC 1 and APC 2 with a non-coated bracket system [Victory Series (V)] using Transbond XT™ light-cured adhesive and TPSEP or 37 per cent phosphoric acid as the conditioner.
The results demonstrated that on dry testing of 120 brackets when applying an occluso-gingival load to produce a shear force at the bracket–tooth interface, there was no statistically significant difference in the shear bond strength (SBS) of APC 1 (68.4 N), APC 2 (74.9 N), and V brackets (75.4 N, control group). There was also no significant difference in bond failure sites of the APC 1 and APC 2 when compared with the non-coated bracket system using Transbond XT light-cured adhesive and TPSEP, with bond failure for all groups occurring mainly at the adhesive–enamel interface. There was a significant difference in the SBS of the V brackets when using TPSEP and 37 per cent phosphoric acid as the conditioners. The latter was lower (60.6 N) and the bond failure site changed from the enamel–adhesive interface to the bracket–adhesive interface.
The shear rebond strengths of all bracket types were statistically significantly lower (P < 0.05) than their initial SBS (APC 1, APC 2, and V: 35.9, 36.7, and 34.1 N, respectively) and the locus of bond failure altered from the adhesive–enamel interface to the bracket–adhesive interface. A clinical trial using TPSEP as a conditioner would be useful as the time taken to remove the adhesive from the enamel surface may be reduced following debond.