Abstract: Disclosed are compositions for bleaching teeth, comprising a single component part or two or more components blended together before each application. The compositions offer extended shelf life and accelerated bleaching action while significantly reducing the possibility of user discomfort. In preferred embodiments, the composition or one of its parts comprises a blend of hydrogen peroxide and carbamide peroxide in a solution having the consistency of a gel or a viscous liquid. The inventive system allows for water in the composition to avoid tissue desiccation and associated user discomfort, without compromising the shelf life of the composition.