An apparatus and a system for delivering a two-tier oxidative therapy to a dental patient. The apparatus is a mouthpiece made of rubber or thermoplastic elastomer that provides a full or partial coverage of the teeth and gums to be treated, firstly with vaporized hydrogen peroxide and later, ozone gas. The design of the mouthpiece encompassing multiple injection tubes also allows all surfaces of all teeth and gums to be treated at the same time, thereby offering a quick, painless and economical procedure to the dental patient.
