Multilayer dental appliances and related methods and systems

1. A multilayer dental appliance comprising 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 first soft polymer layer, wherein the first soft polymer layer comprises a first plurality of soft polymer sub-layers laminated together;

a hard polymer layer;

a second soft polymer layer, wherein the second soft polymer layer comprises a second plurality of soft polymer sub-layers laminated together;

wherein the hard polymer layer is disposed between the first plurality of soft polymer sub-layers and the second plurality of soft polymer sub-layers;

wherein each of the first soft polymer layer and the second soft polymer layer comprises a thermoplastic elastomer, wherein each of the first soft polymer layer and the second soft polymer layer has an ultimate tensile strength of greater than about 5000 psi, an elongation at break of greater than about 200%, a thickness from about 25 μm to about 100 μm, and a hardness of about 60 A to about 85 D; and

wherein the hard polymer layer comprises a co-polyester, wherein the hard polymer layer has a tensile strength at yield between about 4000 psi to 6500 psi, an elongation at break of greater than about 70%, a thickness from about 550 μm to about 750 μm, and a hardness greater than either the first soft polymer layer or the second soft polymer layer.

2. The multilayer dental appliance of claim 1 , wherein the first soft polymer layer and the second soft polymer layer each has a flexural modulus of greater than about 35,000 psi, a compression set greater than 40% after 24 hours at 70° C., and a light transmission between 400 nm and 800 nm of greater than about 75%.

3. The multilayer dental appliance of claim 1 , wherein the hard polymer layer has a tensile modulus greater than 150,000 psi.

4. The multilayer dental appliance of claim 1 , wherein each of the first soft polymer layer and the second soft polymer layer further comprises a material selected from the group consisting of: a thermoplastic polyurethane elastomer, a silicone rubber, an elastomeric alloy, a thermoplastic vulcanizate (TPV) elastomer, a block copolymer elastomer, a polyolefin blend elastomer, a thermoplastic co-polyester elastomer, and a thermoplastic polyamide elastomer, or a combination thereof.

5. The multilayer dental appliance of claim 1 , wherein the hard polymer layer further comprises one or more of: a polyester, a thermoplastic polyurethane, a polypropylene, a polyethylene, a polypropylene and polyethylene copolymer, an acrylic, a polyetheretherketone, a polyamide, a polyethylene terephthalate, a polybutylene terephthalate, a polyetherimide, a cyclic block copolymer, a polyethersulfone, a polytrimethylene terephthalate, or a combination thereof.

6. The multilayer dental appliance of claim 1 comprising a thickness from about 600 μm to about 1000 μm.

7. The multilayer dental appliance of claim 1 , wherein the hard polymer layer comprises at least one of: an elongation at yield of greater than about 4%, an elongation at break of greater than about 70%, a flexural modulus greater than about 150,000 psi, a stress relaxation of greater than about 10% at 24 hours testing in a high humidity environment, or a light transmission between 400 nm and 800 nm of greater than about 75%.

8. A plurality of incremental position adjustment appliances 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, wherein the appliances are shaped to move teeth from one arrangement to a successive arrangement when successively worn by the patient, and wherein at least one of the appliances comprises:

a first soft polymer layer, wherein the first soft polymer layer comprises a first plurality of soft polymer sub-layers laminated together;

a hard polymer layer;

a second soft polymer layer, wherein the second soft polymer layer comprises a second plurality of soft polymer sub-layers laminated together;

wherein the hard polymer layer is disposed between the first plurality of soft polymer sub-layers and the second plurality of soft polymer sub-layers;

wherein each of the first soft polymer layer and the second soft polymer layer comprises a thermoplastic elastomer, wherein each of the first soft polymer layer and the second soft polymer layer has an ultimate tensile strength of greater than about 5000 psi, an elongation at break of greater than about 200%, a thickness from about 25 μm to about 100 μm, and a hardness of about 60 A to about 85 D; and

wherein the hard polymer layer comprises a co-polyester, wherein the hard polymer layer has a tensile strength at yield between about 4000 psi to 6500 psi, an elongation at break of greater than about 70%, a thickness from about 550 μm to about 750 μm, and a hardness greater than either the first soft polymer layer or the second soft polymer layer.

9. The plurality of incremental position adjustment appliances of claim 8 , wherein the first soft polymer layer and the second soft polymer layer each has a flexural modulus of greater than about 35,000 psi, a compression set greater than 40% after 24 hours at 70° C., and a light transmission between 400 nm and 800 nm of greater than about 75%.

10. The plurality of incremental position adjustment appliances of claim 8 , wherein the hard polymer layer has a tensile modulus greater than 150,000 psi.

11. The plurality of incremental position adjustment appliances of claim 8 , wherein the first soft polymer layer and the second soft polymer layer each further comprises a material selected from the group consisting of: a thermoplastic polyurethane elastomer, a silicone rubber, an elastomeric alloy, a thermoplastic vulcanizate (TPV) elastomer, a block copolymer elastomer, a polyolefin blend elastomer, a thermoplastic co-polyester elastomer, and a thermoplastic polyamide elastomer, or a combination thereof.