An apparatus for practicing the inventive method includes a glass ampule having a tooth whitening solution vacuum sealed within a chamber of the ampule. The ampule is contained within a cylindrical plastic sleeve closed at one end and enclosed at its other open end by the proximal termination of a brush-type applicator. An adhesive such as glue is used to adhere the periphery of the brush to the inner surfaces of the plastic cylinder. The bristles preferably have circular cross-sections so that when they are tightly packed together and adhered to the plastic cylinder, interstices between adjacent bristles are sufficiently large enough to permit flow through of the tooth whitening composition while being sufficiently small enough to prevent shards of glass from the ampule, when broken open, to pass through the brush. A cardboard sleeve surrounds the plastic cylinder to protect the user from the glass ampule when broken. The method of using the inventive apparatus is also disclosed.