A method and the resulting product for optimizing the configuration of a mouthpiece for cleaning teeth in which the configuration of the mouthpiece is optimized to the oral geometry of individual users. The method includes a first step (26) of producing a digital scan of the oral geometry of the individual user and then producing a rigid shell (30) for the mouthpiece substantially matching the digital scan. The configuration of the resulting mouthpiece is characterized by the outer surface of the shell not extending from the buccal surface of the individual teeth more than 7 mm (31) further, by the rear edge of the shell not contacting the tissues to the rear of the rearmost teeth (36), and still further by no more than a 2 mm overlap into the gum line (36), when the mouthpiece is operatively positioned in the users mouth.
