Evaluating a Cobalt-Tetraphenylporphyrin Complex, Functionalized with a Reduced Graphene Oxide Nanocomposite, for...

To study using cobalt-tetraphenylporphyrin/reduced graphene oxide (CoTPP/RGO), a nanocomposite highly catalytic both for oxidizing and for reducing hydrogen peroxide (H₂ O₂ ), to whiten teeth.

Dyes (D&C Red 34, Orange No. 4), tea, and betel nuts (Areca catechu) were used to stain the tooth specimens for three days and subsequently bleached using H₂ O₂ alone, H₂ O₂ plus CoTPP, or H₂ O₂ plus CoTPP/RGO for 0.5-70 hours. The process was photographed using an electronic chromometer and a camera. Color change was assessed after each session. The results of bleaching teeth with and without photoirradiation were compared.

CoTPP/RGO increased the tooth-whitening efficacy of H₂ O₂ for specimens stained with dyes, tea, and betel nuts. Using lamps (photoactivation) (wavelengths: 254 nm and 310 nm) to catalyze the H₂ O₂ bleaching agent reduced the bleaching treatment time.

First, the Co/TPP/RGO complex allows improved tooth bleaching and shorter treatment times. Second, because the Co/TPP/RGO complex bleached D&C Red 34 at a similar rate and to a similar degree as tea and other natural agents stain teeth, it is a convenient staining agent for studying many vital aspects of tooth bleaching. (J Esthet Restor Dent 28:321-329, 2016).