Aim: To compare in vitro the effects on shear bond strength of the application of a dental bleaching and desensitizer agent prior to bonding metallic orthodontic brackets to extracted human teeth. Method: Sixty therapeutically extracted human premolars without any visible defects were collected and stored in 0.1% thymol solution at room temperature. All teeth were randomly assigned to one of four groups (each n = 15): group I, teeth were treated with bleaching gel containing 10% carbamide peroxide; group II, teeth were treated with a desensitizer containing 26% potassium oxalate; group III, teeth were treated as in group I followed by application of the desensitizer agent as in group II; and group IV, control group. The teeth from all the four groups were then bonded with 0.018-inch Roth premolar brackets. The shear bond strength was tested in a Hounsfield material testing machine. Results: In group I, 10% carbamide peroxide gel alone did not affect the shear bond strength significantly compared with the unbleached specimens in the control group. The use of the desensitizer agent alone in group II significantly reduced the shear bond strength. In group III, further significant reduction of the mean shear bond strength occurred compared with all the three groups. Conclusion: The use of 10% carbamide peroxide prior to bonding orthodontic metallic brackets does not significantly alter shear bond strength. Application of desensitizer agent alone or in combination with bleaching agent significantly lowers the shear bond strength of orthodontic brackets. Application of desensitizer agent alone or in combination with bleaching agent does not lower the shear bond strength below the recommended value for orthodontic bonding procedure. As a result, their use is not a contraindication before orthodontic fixed mechanotherapy. ORTHODONTICS (CHIC) 2012;13:e181–e187.
Key words: bleaching, carbamide peroxide, desensitizer, shear bond strength