A device, method, and system are provided for treating the oral cavity. The device includes a mouthpiece suitable for implementing a dental treatment, wherein the mouthpiece includes one or more stock elastomeric dental cover layers suitable for forming and maintaining a treatment cavity having a vacuum fluid seal, wherein the dental cover layers includes a layer over all the surfaces of the upper teeth and surrounding gums and/or a layer over all the surfaces of the lower teeth and surrounding gums, wherein each of the layers includes one or more hardened rigid or semi-rigid sections for enabling selected and/or differential collapsibility of the cover layers when exposed to vacuum pressure； and one or more treatment supply layers, and one or more flow channels in fluid communication with the treatment cavity so that the treatment supply layer can deliver and/or remove one or more treatment fluids from the one or more fluid sealed treatment cavities.
