effect of a whitening mouthwash containing blue covarine on enhancing tooth and composite resin discolorations

Objective: this study examined the impact of a blue covarine whitening mouthwash on enhancing the color of stained composite resin specimens and teeth.methods: this in vitro study involved a total of 72 specimens including 36 human incisors and 36 disks prepared from a resin composite. the specimens in each group were randomly distributed to three subgroups (n=12) according to the applied mouthwash: listerine, iwhite and a control group. control specimens were maintained in distilled water throughout the study. the remaining specimens were immersed in a coffee solution for two weeks, then treated with either listerine (containing hydrogen peroxide) or iwhite (containing blue covarine) mouthwashes. the immersion lasted for four minutes daily over 56 days. color assessment was performed by a spectrophotometer at baseline (t1), post-staining (t2), and post-mouthwash immersion (t3) and color change (δe) between stages was calculated.results: significant discoloration was observed after immersion in coffee solution in the experimental groups as compared to the control (p<0.05). the color change between baseline (t1) and after immersion in mouthwashes (t3) was not significantly different between the two experimental groups on tooth samples (p=0.12). however, δe (t1-t3) was significantly lower in iwhite (δe=2.27) than the listerine mouthwash (δe=4.99) on composite specimens (p<0.001).conclusions: both hydrogen peroxide- and blue covarine-containing mouthwashes showed comparable effects in restoring tooth discolorations, although the color changes were detectable after treatment ((δe > 3.3).the mouthwash containing blue covarine (iwhite) restored the original color of composite resin specimens more successfully than the mouthwash containing hydrogen peroxide (listerine).