Patent ID: 9655691
Date: 2017-05-23
CPC Classifications: A61C,A61F,A63B,B29C,B29K,B29L,B32B,Y10T

Claim:
1. A removable orthodontic tooth positioning appliance having teeth receiving cavities shaped to directly receive at least some of a patient's teeth and apply a resilient positioning force to the patient's teeth, the appliance comprising: a hard inner polymer layer comprising a co-polyester and having a hard polymer layer elastic modulus; and a first soft outer polymer layer and a second soft outer polymer layer each comprising a thermoplastic polyurethane elastomer and each having a soft polymer elastic modulus less than the hard polymer layer elastic modulus, a flexural modulus of greater than about 35,000 psi, a hardness of about 60A to about 85D, and a thickness in a range from 25 μm to 100 μm, wherein the hard inner polymer layer is disposed between the first soft outer polymer layer and the second soft outer polymer layer so as to reduce degradation of the resilient positioning force applied to the teeth when the appliance is worn.