What is claimed is:
1. A crystalline ceramic dental mill blank having a Contrast Ratio value less than about 0.7.
2. The mill blank of claim 1 wherein the ceramic is a single crystal.
3. The mill blank of claim 1 wherein the ceramic is polycrystalline.
4. The mill blank of claim 3 wherein the ceramic is single-phase crystalline.
5. The mill blank of claim 3 wherein the ceramic is multi-phase crystalline.
6. The mill blank of claim 1 wherein the blank has a tooth-like shade.
7. The mill blank of claim 1 wherein the ceramic is aluminum oxide.
8. The mill blank of claim 1 wherein the ceramic is selected from the group consisting of magnesium-aluminum spinel, zirconium oxide, yttrium aluminum garnet, zirconium silicate, yttrium oxide and mullite
9. The mill blank of claim 1 wherein the blank has a Contrast Ratio value less than about 0.6.
10. The mill blank of claim 1 wherein the blank has a Contrast Ratio value less than about 0.5.
11. The mill blank of claim 1 wherein the blank, after milling into a Flexural Strength test sample, has a flexural strength greater than about 250 MPa.
12. The mill blank of claim 1 wherein the blank, after milling into a Flexural Strength test sample, has a flexural strength greater than about 350 MPa.
13. The mill blank of claim 1 wherein the blank, after milling into a Flexural Strength test sample, has a flexural strength greater than about 500 MPa.
14. The mill blank of claim 1 wherein the ceramic comprises less than about 5wt % glass.
15. The mill blank of claim 1 wherein the ceramic comprises less than about 2 wt % glass.
16. The mill blank of claim 1 wherein the ceramic is essentially free of oxynitride.
17. The mill blank of claim 1 wherein the blank includes a support stub.
18. A dental mill blank comprising at least 99% polycrystalline ceramic having at least 99% theoretical density and a Contrast Ratio value of less than about 0.7, wherein the blank, after milling into a Flexural Strength test sample, has a flexural strength greater than about 250 MPa.
19. The blank of claim 18 wherein the ceramic is selected from the group consisting of aluminum oxide, yttrium oxide, yttria-alumina garnet, and magnesium-aluminum spinel.
20. A method for making a dental prosthesis comprising the steps of:
a) providing a dental mill blank comprising crystalline ceramic having a Contrast Ratio less than about 0.7; and
b) carving the mill blank into a desired shape.
21. The method of claim 20 wherein the ceramic has a Contrast Ratio less than about 0.6.
22. The method of claim 20 wherein the ceramic has a Contrast Ratio less than about 0.5.
23. The method of claim 20 wherein the carved mill blank has a flexural strength greater than about 250 MPa.
24. The method of claim 20 wherein the carved mill blank has a flexural strength greater than about 350MPa.
25. The method of claim 20 wherein the carved mill blank has a flexural strength greater than about 500 MPa.
26. The method of claim 20 wherein the mill blank is carved into the desired shape in less than about 3 hours.
27. The method of claim 20 wherein the mill blank is carved into the desired shape in less than about 2 hours.
28. The method of claim 20 wherein the mill blank is carved into the desired shape in less than about 1 hour.
29. The method of claim 20 further comprising the step of:
c) adding additional material to the carved blank.
31. The method of claim 20 further comprising the steps of:
c) manually changing the shape of the carved blank and
d) finishing the outer surface of the carved blank.
32. The method of claim 20 wherein the carving is performed by a milling machine.
33. The method of claim 20 wherein the carving is performed by a hand-held instrument.
34. A method for using a dental prosthesis comprising the steps of:
a) providing a dental mill blank comprising crystalline ceramic having a Contrast Ratio less than about 0.7;
b) carving the mill blank into a desired shape; and
c) attaching the carved blank to tooth or bone structure.
35. The method of claim 34, wherein the carved blank is attached to the tooth or bone structure with a color-matching bonding agent.
36. The method of claim 34 further comprising an interim step of:
a) applying a color-matching composition onto a the tooth or bone structure prior to placing the carved blank onto the tooth structure.
37. A multiple-unit kit comprising a crystalline ceramic dental mill blank having a Contrast Ratio less than about 0.7 and instructions for using the mill blank.
38. The kit of claim 37 further comprising a color-matching composition suitable for use in the oral environment.
39. The kit of claim 37 further comprising a bonding agent.
40. The kit of claim 37 further comprising a milling lubricant.
41. A crystalline ceramic dental prosthesis having a Contrast Ratio value less than about 0.7.
42. The prosthesis of claim 41 wherein the ceramic is a single crystal.
43. The prosthesis of claim 41 wherein the ceramic is polycrystalline.
44. The prosthesis of claim 41 wherein the ceramic is single-phase crystalline.
45. The prosthesis of claim 41 wherein the ceramic is multi-phase crystalline.
46. The prosthesis of claim 41 wherein the ceramic is selected from the group consisting of aluminum oxide, magnesium-aluminum spinel, zirconium oxide, yttrium aluminum garnet, zirconium silicate, yttrium oxide and mullite.
47. The prosthesis of claim 41 having a flexural strength greater than about 250 MPa.
48. The prosthesis of claim 41 wherein the ceramic comprises less than about 5wt % glass.
49. The prosthesis of claim 41 wherein the ceramic is essentially free of oxynitride.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An article with at least one switching segment, wherein the at least one switching segment comprises
a) a shape-memory compound comprising at least one thermo-programmable shape memory polymer and particles embedded therein, which particles are suitable to heat up in an alternating electromagnetic field, wherein the shape memory compound has a thermal transfer coefficient hschalt;
b) an isolating region surrounding the shape memory compound a) and having a thermal transfer coefficient hiso;
wherein hiso<hschalt.
2. The article according to claim 1, wherein the ratio hisohschalt is \u22660.9.
3. The article according to claim 1, wherein the isolating region has substantially no particles which are suitable to heat up in an alternating electromagnetic field.
4. The article according to claim 1, wherein the isolating region comprises a material or is made of a material with a specific thermal conductivity \u03bbiso, which is smaller than the specific thermal conductivity \u03bbschalt of the at least one thermo-programmable shape memory polymer of the shape memory compound.
5. The article according to claim 1, wherein the isolating region has a structure which is different from the structure of the shape memory compound.
6. The article according to claim 1, wherein the isolating region has a foam structure.
7. The article according to claim 1, wherein the material of the isolating region comprises a gas.
8. The article according to claim 1, wherein the ratio of the average diameter of the isolating region and the shape memory compound (Diso+schalt) to the average diameter of the shape memory compound (Dschalt) is selected in cross-section of the at least one switching segment (Diso+schaltDschalt such that a switching temperature of the at least one shape memory polymer of the shape memory compound can be attained in the shape memory compound through excitation with an alternating electromagnetic field, wherein the at least one switching segment is in an environment having a thermal transfer coefficient which is greater than the thermal transfer coefficient of the shape memory compound of the switching segment.
9. The article according to claim 8, wherein the diameter ratio Diso+schaltDschalt is selected such that the at least one switching segment attains the switching temperature in an environment of water andor in an alternating electromagnetic field having a frequency of 245 to 265 kHz and a field strength of 10 to 16 kAm.
10. The article according to claim 8, wherein the ratio of the average diameter of the isolating region and of the shape memory compound to the average diameter of the shape memory compound in cross-section of the at least one switching segment is Diso+schaltDschalt\u22671.01.
11. The article according to claim 1, wherein the isolating region comprises pores, which are distributed over the cross-section of the isolating region along a pore size gradient, wherein the pores in an outer region of the isolating region are on average smaller than the pores in an inner region of the isolating region.
12. A method for producing an article with at least one switching segment according to claim 1, comprising the steps of:
a) preparing a shape memory compound of the at least one switching segment, which comprises at least one thermo-programmable shape memory polymer and particles incorporated therein, which particles are suitable to be heated up in an alternating electromagnetic field, wherein the shape memory compound has a thermal transfer coefficient hschalt; and
depositing on the shape memory compound of the at least one switching segment an isolating region which has a thermal transfer coefficient hiso<hschalt, so that the isolating region surrounds the shape memory compound, and
wherein step b) is carried out concurrent with step a) or subsequent to step a).
13. The method according to claim 12 wherein the shape memory compound of the at least one switching segment is produced by deformation from a polymer melt, by a continuous andor discontinuous, single-layer andor multilayer extrusion or injection molding process andor by a joining process of several prefabricated elements.
14. The method according to claim 12, wherein the isolating region is deposited by foaming, by spraying andor by phase inversion.
15. The method according to claim 12, wherein the isolating region is produced by foaming andor phase inversion of the at least one thermo-programmable shape memory polymer of the shape memory compound.
16. The method according to claim 12, wherein the isolating region is produced by foaming andor phase inversion of one or more materials, which are different from the at least one thermo-programmable shape memory polymer of the shape memory compound.
17. The article according to claim 1, wherein the article is in contact with a materials having a thermal transfer coefficient greater than hschalt.
18. (canceled)
19. The article according to claim 17 wherein the material is a liquid or tissue of a human or animal.
20. The article according to claim 2 wherein the ratio hisohschalt is \u22660.1.
21. The article according to claim 2 wherein the gas is CO2 or air.