Effects of different bleaching methods on shear bond strengths of orthodontic brackets.

OBJECTIVE: To evaluate the effects of different bleaching methods on the shear bond strength (SBS) of orthodontic brackets. MATERIALS AND METHODS: Forty-five freshly extracted premolars were randomly divided into three groups (n = 15 per group). In group I, bleaching was performed with the office bleaching method. In group II, bleaching was performed with the home bleaching method. Group III served as the control. Orthodontic brackets were bonded with a light cure composite resin and cured with an LED light. After bonding, the SBS of the brackets were tested with a Universal testing machine. RESULTS: Analysis of variance indicated a significant difference between groups (P < .001). The highest values for SBS were measured in group III (20.99 +/- 2.32 MPa). The SBS was significantly lower in groups I and II than in group III (P < .001). The lowest values for SBS were measured in group II (6.42 +/- 0.81 MPa). SBS was significantly higher in group I than in group II (P < .001). CONCLUSIONS: Both of the bleaching methods significantly affected the SBS of orthodontic brackets on human enamel. Bleaching with the home bleaching method affected SBS more adversely than did bleaching with the office bleaching method.