OBJECTIVE: The objective of this study was to assess, in vitro, the
influence of bleaching gel and the use of desensitizing agent over bond strength
of ceramic brackets bonded to bovine enamel. METHODS: One hundred bovine incisors were selected and randomly divided into five groups
(n = 20): Group 1, control group (without bleaching); Group 2, bleached with 35%
hydrogen peroxide; Group 3, bleached with 35% hydrogen peroxide (three
applications, 15 minutes each) and desensitizing agent applied for 10 minutes;
Group 4, bleached with 35% hydrogen peroxide for 40 minutes; Group 5, bleached
with 35% hydrogen peroxide for 40 minutes with desensitizing agent applied for 10
minutes. Brackets were bonded 7 days after bleaching and submitted to shear bond
strength test after 24 hours at a compression rate of 1 mm/minute. After fracture,
the adhesive remnant index (ARI) was assessed under stereoscopic at 40 x
magnification. Shear strength data (MPa) were submitted to one-way ANOVA and
Tukey's test with significance level set at 5%. RESULTS: Group 5 (29.33 MPa) showed significantly higher bond strength than Group 1 (19.19
MPa), Group 2 (20.59 MPa) and Group 4 (23.25 MPa), but with no difference in
comparison to Group 3. There was no significant difference among the other groups.
The adhesive remnant index showed predominance of score 3, that is, all resin
remained adhered to enamel for all groups. CONCLUSION: Bleaching with 35% hydrogen peroxide with calcium associated with desensitizing
agent application produced higher bond strength values of brackets bonded to
bovine enamel.