The present invention is a switch-closeable double barrel syringe and methods for bleaching teeth using it. The syringe comprises two separately contained barrels, each containing one component of a dental bleach, and a rotatable tip with orifices to match, when open, orifices in the barrels, and a mixing chamber. The tip rotates between open and closed positions in order to dispense bleaching compositions for use in dental hygene. Various formulations of bleaching compositions may be contained within the barrels, however the invention is ideally suited for those which require separate storage of active ingredients before use.