Does the composite attachment of clear aligners compromise the effectiveness of dental bleaching? An in vitro study

This study aimed to evaluate the effectiveness of dental bleaching with hydrogen peroxide 35% on the surface below the attachments. Twenty-four blocks of bovine incisors were equally divided into 2 groups. The control group comprises the enamel surface free of attachments, whereas the attachment group comprises the enamel surface with attachment. Initial staining of samples was performed with black tea for 7 days; then, an attachment was made in the attachment group with Z250 resin and new staining for another 7 days in all samples. After staining, in-office bleaching was performed in both groups, and the attachments from the attachment group were removed. Color reading was performed with a spectrophotometer at all stages: initial (baseline), after 7 days of staining, after 14 days of staining, after immediate bleaching, and after 24 hours of bleaching. The color difference was calculated, and data analysis was performed using the t test for intergroup analysis. The results showed effective bleaching in both groups; however, there was a statistically significant difference in color change between them 24 hours after bleaching. It was concluded that the presence of attachment did not impair the action of the bleaching agent on the tooth surface. •Hydrogen peroxide (35%) was effective for in vitro enamel bleaching under composite attachments.•The attachment did not interfere with tooth whitening.•In-office whitening was effective for in vitro enamel bleaching.•The professional can safely perform in-office bleaching on patients with orthodontic aligners.