Method of manufacturing a prosthetic element

Abstract

A process for preparing a prosthetic element comprising a glass-ceramic body. including the steps of a) providing a basic body comprising an amorphous glass phase and containing the components of the glass-ceramic body to be prepared, and b) transferring energy to the basic body to induce conversion of a starting phase of the material of the basic body into at least one crystalline phase in a confined region. According to the invention, energy is transferred to the confined region of the basic body by laser irradiating said region with a laser beam having a wavelength of at least 500 nm.

Claims

1. A process for preparing a prosthetic element comprising a glass-ceramic body, said process comprising a) providing a basic body comprising an amorphous glass phase and containing the components of the glass-ceramic body to be prepared, and b) transferring energy to the basic body to induce conversion of a starting material of the basic body into at least one crystalline phase in a confined region, wherein energy is transferred to the confined region of the basic body by laser irradiating said region with a laser beam having a wavelength of at least 500 nm; and a first region of the basic body is subjected to a first conversion step to induce formation of a crystalline phase A in the first region, and a second region of the basic body different from the first region is subjected to a second conversion step to induce formation of a crystalline phase B in the second region, wherein the crystalline phase A formed in the first region is different from the crystalline phase B formed in the second region.

2. The process according to claim 1, wherein the laser beam has a wavelength of at least 600 nm.

3. The process according to claim 1, wherein the basic body is heated in the region through laser irradiation.

4. The process according to claim 1, wherein laser irradiation is performed using at least one continuous wave laser.

5. The process according to claim 1, wherein laser irradiation is performed by superposed application of two or more laser beams.

6. The process according to claim 1, wherein the starting phase is amorphous.

7. The process according to claim 1, wherein the basic body is made of an amorphous glass material.

8. The process according to claim 1, further comprising heating the basic body.

9. The process according to claim 8, wherein the basic body is heated to a first temperature before laser irradiation.

10. The process according to claim 9, wherein the first temperature lies in a range of from about 300 C. to about 750 C.

11. The process according to claim 9, wherein the first temperature lies in a range of from about 400 C. to about 750 C.

12. The process according to claim 9, wherein the first temperature lies in a range of from about 600 C. to about 750 C.

13. The process according to claim 9, wherein the first temperature is about 660 C.

14. The process according to claim 1, wherein the glass-ceramic body comprises 65 to 72 wt-% SiO.sub.2, at least 8 wt-% of Li.sub.2O, and at least 8 wt-% of Al.sub.2O.sub.3 based on a total weight of the composition.

15. The process according to claim 1, wherein the glass-ceramic body comprises at least one absorption-increasing ion selected from the group consisting of Nd.sup.3+, Fe.sup.2+, Fe.sup.3+, V.sup.2+, V.sup.3+, V.sup.4+, V.sup.5+, Co.sup.2+, Cr.sup.4+, Cr.sup.6+ and Mn.sup.2+, and mixtures thereof.

16. The process according to claim 1, wherein the proportion of the crystalline phase A is higher in the first region than in the second region and the proportion of the crystalline phase B is higher in the second region than in the first region.

17. The process according to claim 1, wherein the at least one crystalline phase comprises at least one component selected from the group consisting of lithium metasilicate (Li.sub.2SiO.sub.3), lithium disilicate (Li.sub.2Si.sub.2O.sub.5), lithium aluminosilicate (LiAlSi.sub.2O.sub.6, LiAlSiO.sub.4, LiAlSi.sub.3O.sub.8 and/or LiAlSi.sub.4O.sub.10), and Li.sub.3PO.sub.4.

18. The process according to claim 1, wherein the crystalline phase A comprises lithium disilicate as main crystalline phase, and the crystalline phase B comprises lithium aluminosilicate as main crystalline phase.

19. The process according to claim 1, wherein the proportion of the crystalline phase A in the first region changes to the crystalline phase B in the second region in a gradual manner.

20. The process according to claim 1, wherein the prosthetic element is a dental prosthetic element comprising a glass-ceramic body with an enamel area and a dentin area corresponding to the respective areas of a natural tooth, and the first region comprising the crystalline phase A is formed in the enamel area, and the second region comprising the crystalline phase B is formed in the dentin area.

21. The process according to claim 1, further comprising melting an outermost surface of the basic body or the glass-ceramic body by means of laser irradiation followed by solidification of the melted material, thereby providing a gloss to the prosthetic element.

22. The process according to claim 1, further comprising cutting the basic body or the glass-ceramic body into the desired shape for the final prosthetic element, the cutting being performed by means of laser irradiation.

23. The process according to claim 1, wherein the laser beam has a wavelength of at least 700 nm.

24. The process according to claim 1, wherein the laser beam has a wavelength of at least 800 nm.

25. The process according to claim 1, wherein laser irradiation is performed using at least one continuous wave high power diode laser.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of a laser irradiation process of a basic body as described in Example 1;

(2) FIG. 2 is a schematic diagram of a laser irradiation process utilizing two beams that are collimated to increase the effective energy absorbed by the basic body;

(3) FIG. 3 is a top plan view of a basic body subjected to a first conversion step to induce formation of a crystalline phase A in a first region and a second conversion step to induce formation of a crystalline phase B in a second region, and showing an outline of the shape a prosthetic element for a dental restoration to be cut from the basic body;

(4) FIG. 4 is a schematic view of a prosthetic element cut from the basic body of FIG. 3, including first and second regions;

(5) FIG. 5 is a schematic view of a final prosthetic element similar to FIG. 4 but including a melted outer surface.

DETAILED DESCRIPTION

(6) The present invention is further illustrated by way of the following examples.

EXAMPLES

Glass Composition of Basic Body

(7) A glass composition comprising 68 wt-% SiO.sub.2, 10.5 wt-% Li.sub.2O, 10.5 wt-% wt-% Al.sub.2O.sub.2, 0.5 wt-% K.sub.2O, 2.5 wt-% Na.sub.2O, 4.5 wt-% P.sub.2O.sub.5, 0.5 wt-% ZrO.sub.2, 1.45 wt-% CaO, 1.5 wt % CeO.sub.2, 0.05 wt % V.sub.2O.sub.5 is provided according to a standard procedure known to the skilled person.

Example 1

(8) A bar shaped sample 11 having the above composition is put on a ceramic base plate 12 (table) which itself is arranged on a metal support 13. This arrangement is placed in a chamber where the sample is treated by laser irradiation 14 using a LIMO high power continuous wave (cw) diode laser 15 (wavelength =808 nm, optical power=max. 350 W, spot diameter d.sub.F=6 mm, uniform beam profile). The laser beam is thereby directed through a focusing lens 16.

(9) More specific details regarding the laser irradiation in Experiments No.s 1.1 and 1.2 are given in the following:

(10) TABLE-US-00002 Experiment No. # 1.1 1.2 Sample Position on table on table Sample State not not nucleated nucleated Beam Propagation focused focused angle 45 angle 45 Beam Diameter mm 6 6 Optical Power W 180 180 Intensity W/cm.sup.2 636.6 636.6 Irradiation time Min 5 7

(11) A comparison of Experiments 1.1 and 1.2 reveals that during the laser irradiation treatment a translucent violet colour starts to spread from the top to the bottom, followed by a white colour propagating from the centre of the sample, leaving a white crystalline phase in the centre with blue violet surroundings.

Example 2

(12) Samples having the above composition are preheated in a first step during 1 min at 150 W and 1 min at 120 W before laser irradiation treatment using the laser specified in Example 1. More specific details regarding the laser irradiation in Experiment No. 2 are given in the following:

(13) TABLE-US-00003 Experiment No. # 2 Sample on table Position Sample State nucleated glass Beam focused Propagation angle 45 Beam Diameter mm 6 Optical Power W 190 Intensity W/cm.sup.2 672.0 Irradiation Min 3 time

(14) By this treatment, a glass-ceramic sample comprising crystalline phases of white and yellow colour is obtained. The presence of the crystalline phases generated by laser irradiation is confirmed by XRD (X-ray diffraction) measurements which reveal the presence of 39.8% of beta-spodumene (LiAlSi.sub.2O.sub.6), 16.3% of lithium disilicate, 0.8% of dilithium phyllo-disilicate, 6.1% of lithiophosphate (Li.sub.3PO.sub.4), and 0.4% of petalite (LiAlSi.sub.4O.sub.10).

(15) Thus, the examples confirm crystallization in the samples by laser irradiation energy using a laser having a wavelength of 808 nm.

(Comparative) Example 3

(16) For comparative reasons, a sample having the composition defined above for Examples 1 and 2 is treated by laser irradiation using a picosecond laser (wavelength =355 nm (UV)) with a pulse duration of less than 12 picoseconds (ultra-short pulse).

(17) By the process of Example 3, no crystallized areas inside the sample are obtained. Rather, ablation at the surface of the sample is detected.

(Comparative) Example 4

(18) In a further comparative example, a sample having the composition defined above for Examples 1, 2 and 3 is treated by laser irradiation using a nanosecond laser (wavelength =355 nm (UV)) with a pulse duration of less than 20 nanoseconds.

(19) Several laser intensities, focal positions and laser beam diameters are tested. At low laser intensities, no crystallization is detected. Higher laser intensities engenders thermal stresses that result in cracks along with a melting and ablation on the sample surface.