Coloring solution for dental zirconia ceramics and method for using the same

Abstract

A coloring solution for dental zirconia ceramics and a method for using the same are provided. The coloring solution consists of coloring agents, a solvent, and an additive. The coloring agents are a combination of two or more rare earth metal compounds, wherein the rare earth metal compounds having rare earth metal ions selected from the group consisting of praseodymium (Pr) ions, erbium (Er) ions, cerium (Ce) ions, and neodymium (Nd) ions. The concentration of the rare earth metal ions in the solution is 0.053 mol/liter solvent. The molar ratio of Pr ions:Er ions:Ce ions:Nd ions in the solution is 1:(1050):(020):(030).

Claims

1. A coloring solution for dental zirconia ceramics, the coloring solution consists of coloring agents, a solvent, and an additive, wherein the coloring agents are a combination of two or more rare earth metal compounds, wherein the rare earth metal compounds having rare earth metal ions selected from the group consisting of praseodymium (Pr) ions, erbium (Er) ions, cerium (Ce) ions, and neodymium (Nd) ions, the concentration of the rare earth metal ions in the coloring solution is 0.053 mol/liter solvent, and in the solution, the molar ratio of Pr ions:Er ions:Ce ions:Nd ions is 1:(1050):(020):(030); the solvent is one selected from the group consisting of water, methanol, ethanol, isopropanol, n-propanol, glycerol, and ethylene glycol, or mixture of two or more thereof, and the amount of the additive is 0-50 wt %, based on the total weight of the coloring solution.

2. The coloring solution for dental zirconia ceramics according to claim 1, characterized in that, Pr ions:Er ions:Ce ions:Nd ions is 1:(1240):(110):(325).

3. The coloring solution for dental zirconia ceramics according to claim 1, characterized in that, the coloring agents are a combination of soluble salts of the rare earth metal ions, and one or more anions selected from the group consisting of chloride, acetate, nitrate, thiocyanate and sulfate.

4. The coloring solution for dental zirconia ceramics according to claim 1, characterized in that, the additive comprises thixotropic agent which includes one or more selected from the group consisting of glucose, sucrose, polydextrose, polyethylene alcohol, and PEG-600.

5. The coloring solution for dental zirconia ceramics according to claim 1, characterized in that, the additive comprises surfactant which includes one or more selected from the group consisting of octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyoxyethylene fatty acid ester, polyoxyethylene amine.

6. A method of using the coloring solution for dental zirconia ceramics according to claim 1, characterized in that, the method comprises the steps of: step 1: preparing the coloring solution and a pre-sintered body of zirconia ceramics; step 2: treating the pre-sintered body of the zirconia ceramics with the coloring solution; step 3: drying the treated pre-sintered body of the zirconia ceramics; step 4: sintering the dried pre-sintered body of the zirconia ceramics at high temperature.

7. The method of claim 6, characterized in that, the treating of the pre-sintered body of the zirconia ceramics is performed by soaking the pre-sintered body of the zirconia ceramics in the coloring solution; or by brushing, spraying or spin coating the coloring solution on the pre-sintered body of the zirconia ceramic; or by applying the coloring solution on the pre-sintered body of the zirconia ceramics via sponge, or any combination thereof.

8. The method of claim 6, characterized in that, the drying is performed by drying at room temperature, infrared drying, freeze drying, or microwave drying.

9. The method of claim 6, characterized in that, the sintering temperature for sintering at high temperature is from 1300 to 1700 C. and the sintering period is 0.5 to 3 h.

10. The method of claim 9, characterized in that, the sintering temperature for sintering at high temperature is from 1480 to 1600 C.

11. The method of claim 9, characterized in that, the sintering period is 2 h.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the visible light transmittance of the samples obtained in example 6 of the present invention and comparative examples 1 and 2, wherein the different bodies of the pre-sintered zirconia ceramics are colored with three different coloring solutions, after sintering, all of the samples show a substantially same color.

(2) FIG. 2 shows the visible light transmittance of the samples obtained in example 6 of the present invention and comparative examples 1 and 2, wherein the same bodies of the pre-sintered zirconia ceramics are colored with three different coloring solutions, after sintering, all of the samples show a substantially same color.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) Hereafter, some specific embodiments of the present invention will be described in detail, with reference to the examples and figures. However, the examples described are only some illustrated examples of the present invention, not all of the examples of the present invention. Based on the examples provided herein, all of the other examples, obtainable for a person skilled in the art without any creative work, are also fall within the scope of protection of the present invention.

EXAMPLE 1

(4) A coloring solution containing Pr(NO.sub.3).sub.3 and Er(NO.sub.3).sub.3 was prepared, wherein the concentration of Pr(NO.sub.3).sub.3 was 0.005 mole/liter, and the concentration of Er(NO.sub.3).sub.3 is 0.060 mole/liter. Water was used as solvent. Polydextrose is added to the aqueous solution in a concentration of 10 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er is 1:12.

(5) A zirconia ceramic body having a porosity of 50% was prepared by shaping a 3Y-TZP powder via isostatic pressing, and then sintering at 1000 C. for 2 hours.

(6) The coloring solution prepared was brushed on the pre-sintered body of the zirconia ceramics by using a writing brush. The coloring solution was brushed for 7 times in total.

(7) The coated pre-sintered body of the zirconia ceramics was infrared dried for 20 minutes, and then sintered in a box-type electric furnace at a temperature of 1600 C. for 1.5 hour. A colored dental prosthesis was obtained.

EXAMPLE 2

(8) A coloring solution, containing PrCl.sub.3 of 0.009 mole/liter solvent, ErCl.sub.3 of 0.153 mole/liter solvent, and NdCl.sub.3 of 0.027 mole/liter solvent as coloring agents, was prepared. Water was used as solvent. Glucose was added into the aqueous solution, as an additive, in a concentration of 30 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er:Nd is 1:17:3.

(9) A pre-sintered body of zirconia ceramics was prepared as in example 1.

(10) The coloring solution was applied on the pre-sintered body of the zirconia ceramics with a sponge, until the coloring solution can not permeate into the colored green body any more.

(11) The coated body of the zirconia ceramics was freeze dried at 30 C. for 3 hours, then sintered in a box-type electric furnace at a temperature of 1500 C. for 3 hours. A colored dental prosthesis according to the present example was obtained.

EXAMPLE 3

(12) A coloring solution, containing PrAc.sub.3 of 0.015 mole/liter solvent, ErAc.sub.3 of 0.252 mole/liter solvent, and NdAc.sub.3 of 0.107 mole/liter solvent as coloring agents, was prepared. Water was used as solvent. PEG-600 was added as an additive, with a concentration of 25 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er:Nd is 1:16.8:7.1.

(13) A pre-sintered body of zirconia ceramics was prepared as in example 1. The pre-sintered body of zirconia ceramics was soaked in the coloring solution for 5 minutes.

(14) The soaked body of the zirconia ceramics was dried at room temperature for 2 hours, then sintered in a box-type electric furnace at a temperature of 1480 C. for 2 hours. A dental prosthesis according to the present example was obtained.

EXAMPLE 4

(15) A coloring solution, containing Pr(NO.sub.3).sub.3 of 0.018 mole/liter solvent, Er(NO.sub.3).sub.3 of 0.262 mole/liter solvent, and Nd(NO.sub.3).sub.3 of 0.092 mole/liter solvent as coloring agents, was prepared. Water was used as solvent. Sucrose was added as additive, with a concentration of 20 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er:Nd is 1:14.6:5.1.

(16) A pre-sintered green body of zirconia ceramic was prepared as in example 1, and then brushed the coloring solution prepared in the present example for 2 or 3 times. Then, the coloring solution was further sprayed on the green body until the zirconia ceramic body was saturated by the coloring solution.

(17) The coated body of the pre-sintered zirconia ceramics was dried via microwave for 15 minutes, then sintered in a box type electric furnace at a temperature of 1700 C. for 0.5 hour. A dental prosthesis according to the present example was obtained.

EXAMPLE 5

(18) A coloring solution, containing PrCl.sub.3 of 0.035 mole/liter solvent, ErCl.sub.3 of 0.438 mole/liter solvent, and NdCl.sub.3 of 0.211 mole/liter solvent as coloring agents, was prepared. Water was used as solvent. PEG was added as an additive, with a concentration of 15 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er:Nd is 1:12.5:6.0.

(19) Then the related steps in example 1 were carried out. A dental prosthesis according to the present example was obtained.

EXAMPLE 6

(20) A coloring solution, containing Er(NO.sub.3).sub.3 of 0.40 mole/liter solvent, Pr(NO.sub.3).sub.3 of 0.01 mole/liter solvent, Ce(NO.sub.3).sub.3 of 0.01 mole/liter solvent, and Nd(NO.sub.3).sub.3 of 0.1 mole/liter solvent as coloring agents, was prepared. Water was used as solvent. Polydextrose was added as an additive, with a concentration of 20 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er:Ce:Nd is 1:40:1:10.

(21) Then the related steps in example 1 were carried out. A dental prosthesis according to the present example was obtained.

EXAMPLE7

(22) A coloring solution, containing Er(NO.sub.3).sub.3 of 0.30 mole/liter solvent, Pr(NO.sub.3).sub.3 of 0.01 mole/liter solvent, Ce(NO.sub.3).sub.3 of 0.10 mole/liter solvent, and Nd(NO.sub.3).sub.3 of 0.10 mole/liter solvent as coloring agents, was prepared. Water was used as solvent. Polydextrose was added as an additive, with a concentration of 20 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er:Ce:Nd is 1:30:10:10.

(23) Then the related steps in example 1 were carried out. A dental prosthesis according to the present example was obtained.

EXAMPLE 8

(24) A coloring solution, containing Er(NO.sub.3).sub.3 of 0.20 mole/liter solvent, Pr(NO.sub.3).sub.3 of 0.01 mole/liter solvent, Ce(NO.sub.3).sub.3 of 0.05 mole/liter solvent, and Nd(NO.sub.3).sub.3 of 0.25 mole/liter solvent as coloring agents, was prepared. Water was used as the solvent. Polydextrose was added as the additive, with a concentration of 20 wt %, based on the total weight of the solution. In this solution, the molar ratio of Pr:Er:Ce:Nd is 1:20:5:25.

(25) Then the related steps in example 1 were carried out. A dental prosthesis according to the present example was obtained.

COMPARATIVE EXAMPLES 1 and 2

(26) The steps of example 1 were repeated with the exception that a commercial coloring solution for dyeing dental zirconia ceramic 1 sold under the trade name PRETTAU AQUARELL A3 (ZIRKONZAHN) and a commercial coloring solution for dyeing dental zirconia ceramic 2 sold under the trade name LAVA PLUS HIGH TRANSLUCENCY ZIRCONIA DYEING LIQUID A3 (3M ESPE) were used instead of the coloring solution prepared in example 1, to obtain the samples of comparative examples 1 and 2 respectively.

COMPARATIVE EXAMPLE 3

(27) A coloring solution, containing Ce.sub.2(SO.sub.4).sub.3 of 1.230 mole/liter solvent, Gd.sub.2(SO.sub.4).sub.3 of 0.635 mole/liter solvent, and Te.sub.2(SO.sub.4).sub.3 of 1.135 mole/liter solvent as coloring agents, was prepared. Ethylene glycol was used as the solvent. Polyethylene alcohol with a concentration of 30 wt % was used as the additives, based on the total weight of the solution. In this solution, the molar ratio of Ce:Gd:Te is 1.9:1:1.8.

(28) Then the related steps in example 1 were carried out. A dental prosthesis according to this comparative example was obtained.

COMPARATIVE EXAMPLE 4

(29) A coloring solution, containing CeCl.sub.3 of 1.031 mole/liter solvent, EuCl.sub.3 of 0.125 mole/liter solvent, and NdCl.sub.3 of 1.335 mole/liter solvent as coloring agents, was prepared. A 1:1 mixture of ethanol and water was used as the solvent. PEG 1000 with a concentration of 15 wt % was used as the additives, based on the total weight of the solution. In this solution, the molar ratio of Ce:Eu:Nd is 8.25:1:10.68.

(30) Then the related steps in example 1 were carried out. A dental prosthesis according to this comparative example was obtained.

(31) Both the color and the appearance (e.g., the transmittance) of the dental prostheses prepared according to comparative examples 3 and 4 fail to meet the requirements of the dental prosthesis in clinical.

(32) Measurement and Evaluation

(33) Bend strength of the samples of examples 1 to 8 and comparative examples 1 to 4 were measured by three-point bending method. The size of samples is that, width: (40.2) mm; thickness (1.20.2) mm, and length: above 20 mm.

(34) Measuring method: Cross section size of each sample was measured, with accuracy of 0.01. Span distance was adjusted to 16 mm. A sample was placed in the center of the supporting point of the jig, a load was applied on the surface of the sample in direction vertical to the long axis of the sample. The load was applied by the test machine with a speed of (1.00.5) mm/minute until the sample broke. The load on breaking was recorded.

(35) Three-point bending strength M of each sample was calculated according to the following equation:

(36) $M=\frac{3\mathrm{WL}}{2{\mathrm{bd}}^2}$

(37) wherein:

(38) MBending Strength, MPa;

(39) Wthe maximum load on the sample until broken, N;

(40) Lspan distance, mm;

(41) bwidth of the sample, mm;

(42) dthickness of the sample, mm.

(43) Lambde 650 ultraviolet-visible spectrophotometer was used to determine the transmittance of the samples, the wavelength is in a range of from 380 to 780 nm. The visible transmittance of the samples of examples 1 to 8 and comparative examples 1-4 were measured.

(44) Size of the sample: diameter of above 25 mm and thickness of 1.00.01 mm.

(45) The measured bending strengths and transmittances were listed in below table 1.

(46) TABLE-US-00001 TABLE 1 The three-point bending strengths and transmittances of the sample of zirconia colored by the different coloring solutions three-point bending Visible light Coloring agents Additives strength transmittance (mol/L) Solvent wt % MPa % blank no No no 1371 42.93 example 1 Pr(NO.sub.3).sub.3 0.005 water polydextrose 1248 42.15 Er(NO.sub.3).sub.3 0.060 10 example 2 PrCl.sub.3 0.009 water Glucose 1157 40.88 ErCl.sub.3 0.153 30 NdCl.sub.3 0.027 example 3 PrAc.sub.3 0.015 water PEG 600 1182 39.78 ErAc.sub.3 0.252 25 NdAc.sub.3 0.107 example 4 Pr(NO.sub.3).sub.3 0.018 water sucrose 1139 39.50 Er(NO.sub.3).sub.3 0.262 20 Nd(NO.sub.3).sub.3 0.092 example 5 PrCl.sub.3 0.035 water PEG 1092 38.69 ErCl.sub.3 0.438 15 NdCl.sub.3 0.211 example 6 Pr(NO.sub.3).sub.3 0.01 water polydextrose 1289 38.50 Ce(NO.sub.3).sub.3 0.01 20 Er(NO.sub.3).sub.3 0.4 Nd(NO.sub.3).sub.3 0.1 example 7 Er(NO.sub.3).sub.3: 0.30, water polydextrose 1089 39.0 Pr(NO.sub.3).sub.3: 0.01, 20 Ce(NO.sub.3).sub.3: 0.10, Nd(NO.sub.3).sub.3: 0.10 example 8 Er(NO.sub.3).sub.3: 0.20, water polydextrose 1154 39.4 Pr(NO.sub.3).sub.3: 0.01, 20 Ce(NO.sub.3).sub.3: 0.05, Nd(NO.sub.3).sub.3: 0.25 comparative Coloring solution 1135 26.8 example 1 for dyeing dental zirconia ceramic 1 (PRETTAU AQUARELL A3 (ZIRKONZAHN )) comparative Coloring solution 1131 30.1 example 2 for dyeing dental zirconia ceramic 2 (LAVA PLUS HIGH TRANSLUCENCY ZIRCONIA DYEING LIQUID A3 (3M ESPE)) comparative Ce.sub.2(SO.sub.4).sub.3 1.230 ethylene polyethylene 989 36.86 example 3 Gd.sub.2(SO.sub.4).sub.3 0.635 glycol alcohol Te.sub.2(SO.sub.4).sub.3 1.135 30 comparative CeCl.sub.3 1.031 water, PEG 1000 953 35.94 example 4 EuCl.sub.3 0.125 ethanol 15 NdCl.sub.3 1.335 Notes Visible light transmittance = transmittance at wavelength of 550 nm 1.19;

(47) The blank sample is that obtained by subjecting the pre-sintered zirconia of example without treating by the coloring solution to the sintering process of example 1.

(48) To evaluate the appearance of the obtained dental prosthesis, 20 ordinary persons with good eyesight ranging from 25 to 40 years old were randomly selected. Appearance of the dental prostheses samples obtained in examples 1 to 8 and comparative examples 1-4 were evaluated and scored by these peoples. The samples were scored as 0 to 5, wherein the sample having appearance most close to the natural teeth is scored as 5, and the blank sample is scored as 0. The samples that having intermediate appearance are correspondingly scored according to the degree that their appearance is close to that of the natural teeth, wherein, the more their appearance closes to that of the natural teeth, the higher score is given. All of the results given by these 20 peoples were averaged, and listed in table 2.

(49) TABLE-US-00002 TABLE 2 Scores of the appearance of the samples. average score example 1 4.5 example 2 4.7 example 3 4.65 example 4 4.65 example 5 4.8 example 6 4.9 example 7 4.95 example 8 4.85 comparative example 1 3.9 comparative example 2 4.1 comparative example 3 3.5 comparative example 4 3.3

(50) FIG. 1 shows the comparison of the transmittance of the samples obtained by using a commercial coloring solution for dyeing dental zirconia ceramic 1 sold under the trade name PRETTAU AQUARELL A3 (ZIRKONZAHN), a commercial coloring solution for dyeing dental zirconia ceramic 2 sold under the trade name LAVA PLUS HIGH TRANSLUCENCY ZIRCONIA DYEING LIQUID A3 (3M ESPE), and the coloring solution prepared in example 6 of the present invention (UPZIR A3). In FIG. 1, pre-sintered body of zirconia ceramic 1 (sold under the trade name PRETTAU ZIRCONIA (ZIRKONZAHN)), pre-sintered body of zirconia ceramic 2 (sold under the trade name LAVA PLUS HIGH TRANSLUCENCY ZIRCONIA (3M ESPE)) and pre-sintered body of zirconia ceramic 3 (sold under the trade name UPCERA ST (UPCERA)) were used, and the three kinds of samples of dental prosthesis obtained therefrom showed a substantially same color. After chemical analysis, it is proved that both of two kinds of commercial solutions contain ions of transitional metals. It can be seen from FIG. 1 that, highest visible light transmittance was obtained by using the coloring solution according to example 6 of the present invention.

(51) FIG. 2 shows that the samples of the dental prosthesis, obtained by treating the pre-sintered body of zirconia, UPCERA ST dental corona, with the coloring solution of the present invention (UPZIR A3) and the commercial coloring solution for dyeing dental zirconia ceramic 1 sold under the trade name PRETTAU AQUARELL A3 (ZIRKONZAHN) and commercial coloring solution for dyeing dental zirconia ceramic 2 sold under the trade name LAVA PLUS HIGH TRANSLUCENCY ZIRCONIA DYEING LIQUID A3 (3M ESPE), have a similar color. It can be seen from FIG. 2 that, the highest visible light transmittance was obtained by using the coloring solution according to the present invention.

(52) Some specific examples are described hereinbefore. These examples are for the purpose of clearly illustrating the present invention, not for limiting the scope of protection of the present invention. Without going beyond the spirit and principle of the present invention, any modification, substitution, and improvement etc, fall within the scope of the present invention.