Improved dental appliances and polymeric sheets are disclosed. The dental appliances and polymeric sheets are useful for making dental appliances having outer layers comprised of a material having a modulus of from about 1,000 MPA to 2,500 MPA ("hard") and an inner core comprised of elastomeric material or materials having a modulus of from about 50 MPa to 500 MPa ("soft"), which exhibit improved flexibility and strength and better stain resistance than currently available materials and dental appliances.
