Systems and methods for varying elastic modulus appliances
The present invention provides improved devices, systems and methods for repositioning teeth from an initial tooth arrangement to a final tooth arrangement. Repositioning is accomplished with a system comprising a series of polymeric shell appliances configured to receive the teeth and incrementally reposition individual teeth in a series of successive steps. The individual appliances may be formed from layers having different stiffnesses (elastic moduluses), and the stiffnesses of successive appliances may be different, or both.
1. A method for producing an orthodontic appliance, the method comprising:
providing a mold of patient's dentition;
forming a first material layer over the mold;
removing one or more portions of the first material layer after forming the first material layer to form a remaining portion and one or more removed portions of the first material layer, at least one of the one or more removed portions spanning a group of two or more teeth of the patient's dentition; and
forming a second material layer over the remaining portion of the first material layer so as to produce the orthodontic appliance.
2. The method of claim 1 , wherein the second material layer spans the entirety of the patient's dentition and the remaining portion of the first material layer spans less than the entirety of the patient's dentition after removing the one or more portions.
3. The method of claim 1 , wherein the remaining portion of the first material layer forms an inner layer of the orthodontic appliance and the second material layer forms an outer layer of the orthodontic appliance.
4. The method of claim 3 , wherein an overlapping portion comprises a stiffness greater than a stiffness of the first material layer and a stiffness of the second material layer, the overlapping portion comprising a portion of the first material layer and a portion of the second material layer where the first material layer overlaps a portion of the second material layer.
5. The method of claim 3 , wherein an elastic modulus of an overlapping portion is greater than an elastic modulus of a non-overlapping portion, the overlapping portion comprising a portion of the first material layer and a portion of the second material layer where the first material layer overlaps a portion of the second material layer.
6. The method of claim 1 , wherein the first material layer differs from the second material layer with respect to one or more of the following: elastic modulus, polymer type, or thickness.
7. The method of claim 1 , wherein the first material layer is the same as the second material layer with respect to one or more of the following: elastic modulus, polymer type, or thickness.
8. The method of claim 1 , wherein the first material layer has a greater stiffness than the second material layer.
9. The method of claim 1 , wherein the orthodontic appliance varies in stiffness along one or more of a mesial-distal axis, a facial-lingual axis, or a gingival-crown axis.
10. The method of claim 1 , wherein the orthodontic appliance comprises an occlusal surface having a lower stiffness than the remaining surfaces of the orthodontic appliance.
11. The method of claim 1 , wherein the second material layer is continuous along a mesial-distal axis, and wherein the formed first material layer is discontinuous along the mesial-distal axis.
12. The method of claim 1 , wherein at least one of the removed one or more portions is sized to cover only a portion of a tooth of the patient's dentition.
13. The method of claim 1 , wherein at least one of the removed one or more portions is sized to span a gingival line of the patient's dentition.
14. The method of claim 1 , wherein removing the one or more portions comprises segmenting the first layer into a plurality of sections each shaped to receive one or more of the patient's teeth.
15. The method of claim 1 , wherein the orthodontic appliance comprises one or more gaps formed between two or more remaining portions.
16. The method of claim 1 , wherein the mold comprises a positive model of the patient's dentition in a desired tooth arrangement.
17. The method of claim 1 , wherein forming the first material layer comprises thermoforming the first material layer over the mold and forming the second material layer comprises thermoforming the second material layer together with the first material layer.
18. The method of claim 1 , further comprising trimming the orthodontic appliance for patient use.