Embodiments include dental appliances, dental appliance systems, and methods of making and using such appliances. In one embodiment, a dental appliance includes a shell having a number of cavities to receive one or more teeth, each cavity having an inner surface. Fewer than all cavities are scaled-up in size by a first selected percentage over one or more dimensions of a corresponding tooth surface to provide a uniform space between the cavity inner surface and the corresponding tooth surface.
