METHODS OF CONTROLLING HAZE IN ORTHODONTIC APPLIANCES INCLUDING SEMI-CRYSTALLINE POLYMERS

A dental appliance includes a polymeric shell with a plurality of cavities for receiving one or more teeth, including an interior region with a core layer of a first thermoplastic polymer A with a thermal transition temperature of about 70° C. to about 140° C. and a flexural modulus greater than about 1.3 GPa, and first and second interior layers of a second thermoplastic polymer B with a glass transition temperature of less than about 0° C., a flexural modulus less than about 1 GPa, and an elongation a break of greater than 150%; and first and second exterior layers of a third thermoplastic polymer C with a thermal transition temperature of about 70° C. to about 140° C. and a flexural modulus greater than about 1.3 GPa. The dental appliance demonstrates enhanced optical properties, with enhanced light transmission and low haze.