阅读说明：本技术 低熔点玻璃陶瓷 (Low-melting glass-ceramics ) 是由 贝里特·格迪克 迈克尔·哈克内尔 于 2020-05-06 设计创作，主要内容包括：本发明涉及一种用于牙科框架结构贴面的玻璃陶瓷、其制备方法及在生产牙科修复体中的应用,其中所述玻璃陶瓷的特点在于高含量的B<Sub>2</Sub>O<Sub>3</Sub>。(The invention relates to a glass ceramic for dental framework structure veneering, a method for the production thereof and the use thereof for producing dental restorations, wherein the glass ceramic is characterized by a high B content 2 O 3 。)

1. A glass-ceramic for dental framework structure veneering, characterized in that said glass-ceramic comprises

60-75% by weight of SiO₂；

6-12% by weight of B₂O₃(ii) a And

6-12% by weight of K₂O；

Based in each case on the total weight of the glass ceramic.

2. The glass-ceramic according to claim 1, wherein the glass-ceramic has a softening point of less than 790 ℃, preferably less than 780 ℃, more preferably 730-770 ℃, as determined by heating microscopy.

3. The glass-ceramic of either or both of claims 1 and 2, wherein the glass-ceramic comprises 7 to 9 weight percent K₂O, based on the total weight of the glass-ceramic.

4. The glass-ceramic according to at least one of the preceding claims, wherein the glass-ceramic further comprises 3 to 11 wt.% Al₂O₃Preferably 5 to 9% by weight, based on the total weight of the glass-ceramic.

5. The glass-ceramic according to at least one of the preceding claims, wherein the glass-ceramic further comprises 4 to 11 wt.% Na₂O, preferably 5 to 7% by weight, based on the total weight of the glass-ceramic.

6. The glass-ceramic according to at least one of the preceding claims, wherein the glass-ceramic further comprises less than 3% by weight of Li₂O, preferably less than 2% by weight, more preferably from 0.1 to 1.5% by weight, based on the total weight of the glass-ceramic.

7. The glass-ceramic according to at least one of the preceding claims, wherein the glass-ceramic has a coefficient of thermal expansion CTE lower than 9.5 x 10^-6K^-1Preferably less than 9.3 x 10^-6K^-1More preferably 8.3 x 10^-6K^-1-9.3*10^-6K^-1Or 8.3 x 10^-6K^-1-9.0*10^-6K^-1It is measured by a dilatometer.

8. The glass-ceramic according to at least one of the preceding claims, characterized in that the glass-ceramic has a solubility of less than 20 μ g/cm²Preferably less than 10. mu.g/cm²More preferably 1 to 5. mu.g/cm²Determined according to DINISO 6872.

9. Glass-ceramic according to at least one of the preceding claims, characterized in that the translucency of the glass-ceramic is higher than 75%, preferably higher than 80%.

10. The glass-ceramic according to at least one of the preceding claims, characterized in that the glass-ceramic is essentially free of lithium disilicate and/or lithium metasilicate.

11. The glass-ceramic according to at least one of the preceding claims, wherein the glass-ceramic comprises leucite.

12. The glass-ceramic according to at least one of the preceding claims, wherein the glass-ceramic comprises 0.1 to 10 wt.% leucite, preferably 0.2 to 5 wt.%, or 1 to 4 wt.%.

13. A method for producing a glass ceramic according to at least one of claims 1 to 12, characterized in that the method comprises the following steps:

a) preparing a starting glass by melting a base component and quenching in water;

b) grinding the glass in step a) to obtain a powder;

c) pressing the powder of step b) to obtain a blank;

d) heat-treating the blank to obtain a glass-ceramic; and

e) grinding the blank in step d) to obtain a powder.

14. Glass according to at least one of claims 1 to 12Use of ceramics in veneering of dental framework structures, preferably of lithium disilicate or ZrO₂A base ceramic frame structure.

15. The use of claim 14, wherein the facing structure has a coefficient of thermal expansion CTE_VSCoefficient of thermal expansion CTE with said frame structure_FSThe difference is not more than 2.5 x 10^-6K^-1Preferably less than 1.5X 10^-6K^-1More preferably less than 1.0X 10^-6K^-1Wherein said coefficients of thermal expansion can be separately measured using dilatometers.

16. Dental restoration comprising a framework structure and a veneer structure, characterized in that the veneer structure is a glass ceramic according to at least one of claims 1 to 12.

17. Dental prosthesis according to claim 16, characterized in that the thickness of the surfacing structure is 0.2-3mm, preferably 0.5-1.5 mm.

18. Paste comprising a liquid medium and a powder of a glass-ceramic according to at least one of claims 1 to 12 for use in the veneering of a dental framework structure.

19. A method for producing a dental restoration, characterized in that a glass ceramic according to at least one of claims 1 to 12 or a paste according to claim 18 is applied to a framework structure.

Another disadvantage of the glass-ceramics known from the prior art is their high softening point, which complicates the processing and thus requires high temperatures during production, which greatly prolongs the time for completing the dental restoration. In addition, another disadvantage of the above-mentioned high-melting-point facing materials is that their firing temperature exceeds the softening point of the glass ceramic used to form the frame structure, particularly if the frame structure is composed of lithium silicate glass ceramic. The softening point of such glass-ceramics is typically 780-840 ℃, depending on their composition. It is not possible to veneer the frame with such materials which are already very common in the dental market, because the frame is deformed during the firing of the veneering material. At ZrO₂Problems with high melting point facing materials are also found in framing materials. Albeit ZrO₂Is much higher than the softening point of all known facing materials, but in order to match the patient's tooth color as much as possible, the dental sector often uses porous presintered ZrO which is colored with a coloring liquid₂A frame. However, if these colored ZrO are sintered densely, then₂The frame is heated again to 850 c or more, the coloring component contained therein will be partially oxidized, and depending on the composition of the coloring liquid used, deviation in color fidelity may occur.

It is therefore an object of the present invention to provide a glass ceramic for the facing of frame structures which has good processability and which, on the one hand, forms a stable bond with the frame structure. On the other hand, glass ceramics are characterized by good optical properties, which allow the natural color gradient of teeth to be reproduced.

Surprisingly, it has been found that B is present in high amounts₂O₃The glass-ceramic of (1) can achieve this object.

The invention therefore relates firstly to a glass ceramic for dental framework structure veneering, which contains 60 to 75% by weight of SiO₂(preferably 65-70%% by weight), 6-12% by weight of B₂O₃(preferably 7-10% by weight) and 6-12% by weight of K₂O, each based on the total weight of the glass-ceramic.

The glass ceramic according to the invention is distinguished in particular by a relatively low softening point, which is why material-saving processing is possible, which is particularly important in relation to the temperature sensitivity of the material of the frame structure. It has surprisingly been found that due to the low processing temperature of the glass ceramic and its softening temperature, the frequently occurring deformation of the frame structure is reduced and the bonding between the facing ceramic and the frame structure is improved. Within the scope of the present invention, it has been found to be particularly advantageous if the glass-ceramic has a softening point of not more than 800 ℃. Thus, in a preferred embodiment of the glass-ceramic of the present invention, the glass-ceramic has a softening point of less than 790 ℃, preferably less than 780 ℃, more preferably 730-770 ℃. The softening point can be determined by using a heated microscope, for example, as described in DIN 51730.

In particular, the properties of the glass-ceramic of the invention are matched to the properties of the material used for producing the frame structure in order to ensure a stable bond between the frame structure and the facing ceramic. In particular, the glass-ceramic may further comprise a component for adjusting its thermal properties.

In a preferred embodiment, the glass ceramic of the invention also comprises from 7 to 9% by weight of K₂O, based in each case on the total weight of the glass ceramic. In the composition of the invention K₂The presence of O favors the formation of leucite crystals in the glass-ceramic of the invention. The presence of leucite crystals in the glass-ceramic of the invention enhances its physical properties and acid resistance. In a preferred embodiment of the invention, the glass-ceramic comprises leucite (K [ A ])lSi₂O₆]). In another embodiment of the present invention, the glass-ceramic has a crystalline phase, which preferably comprises leucite as its main component.

In one embodiment, the glass-ceramic comprises 0.1 to 10% by weight of leucite, preferably 0.2 to 5% by weight or 1 to 4% by weight. The leucite content can be determined by the Rietveld method.

In another preferred embodiment, the glass-ceramic contains 3 to 11% by weight Al₂O₃Preferably 5 to 9% by weight. Al (Al)₂O₃Also beneficial to the acquisition of leucite crystals in the glass-ceramic of the invention.

Na₂The presence of O has also proven advantageous. Thus, in a preferred embodiment, the glass-ceramic of the invention contains 4 to 11% by weight of Na₂O, preferably 5 to 7% by weight, based in each case on the total weight of the glass ceramic.

It has been demonstrated that the present invention uses B in an amount₂O₃And K₂The interaction of O is particularly advantageous for structural reinforcement of the glass-ceramic.

In contrast to other alkali metal oxides, Li in glass-ceramics₂The presence of O has little advantage, particularly in view of the composite bond with the frame structure. Thus, in a preferred embodiment of the glass-ceramic of the invention, the glass-ceramic comprises Li₂The content of O is less than 3% by weight, preferably less than 2% by weight, more preferably from 0.1 to 1.5% by weight, based in each case on the total weight of the glass ceramic. In addition, low content of Li₂O prevents the formation of lithium silicate crystals in the glass-ceramic of the invention.

Preferably, the presence of lithium silicate crystals in the glass crystals of the invention should be kept low in order not to adversely affect the physically and chemically advantageous properties.

In a further advantageous embodiment of the invention, the content of lithium silicate crystals is less than 1% by weight, in particular less than 0.1% by weight, in particular less than 0.01% by weight, based on the total weight of the glass-ceramic. Particularly preferred are glass ceramics that are substantially free of lithium disilicate and/or lithium metasilicate. In the meaning of the present invention, "substantially free" means a content of less than 0.01% by weight, preferably completely free. The content of lithium silicate crystals in the glass-ceramic can be determined by the Rietveld method.

In a particularly preferred embodiment, the glass ceramic of the invention comprises the following components:

60-75% by weight, preferably 65-70% by weight, of SiO₂；

6-12% by weight, preferably 7-10% by weight, of B₂O₃；

6-12% by weight, preferably 7-9% by weight, of K₂O；

3-11% by weight, preferably 5-9% by weight, of Al₂O₃；

4-11% by weight, preferably 5-7% by weight, of Na₂O；

0 to 3% by weight, preferably 0.1 to 1.5% by weight, of Li₂O；

Wherein the weight percentages are based in each case on the total weight of the glass ceramic.

In order to increase the translucency, it has proven advantageous if the glass ceramic according to the invention comprises a low content of a component selected from BeO, TiO₂、ZnO、BaO、P₂O₅、PbO、CaF₂And NaF, preferably in an amount of less than 1.5% by weight, in particular less than 1.0% by weight, in particular less than 0.5% by weight or less than 0.1% by weight. Glass-ceramics substantially free of the above-mentioned components are also preferred.

In a further preferred embodiment, the glass ceramic of the invention comprises less than 0.5% by weight of ZnO, preferably less than 0.1% by weight of ZnO, based in each case on the total weight of the glass ceramic. In a particularly preferred embodiment of the invention, the glass ceramic of the invention is substantially free of ZnO.

In a further preferred embodiment, the glass ceramic of the invention contains less than 15% by weight of ZrO₂Preferably less than 5% by weight of ZrO₂More preferably less than 1% by weight of ZrO₂Based on the weight of the glass-ceramic, respectively. In a particularly preferred embodiment of the invention, the glass ceramic of the invention is substantially free of ZrO₂。

In a further preferred embodiment, the glass ceramic of the invention comprises less than 0.5% by weight of BaO, preferably less than 0.1% by weight of BaO, based in each case on the total weight of the glass ceramic. In a particularly preferred embodiment of the invention, the glass ceramic of the invention is substantially free of BaO.

In a further embodiment of the invention, the total amount of the components consisting of BaO and ZnO is less than 1.0% by weight, preferably less than 0.5% by weight, in particular less than 0.1% by weight, based in each case on the total weight of the glass ceramic.

For glass-ceramics, the person skilled in the art knows the following facts: describing the components of the glass-ceramic in the form of oxides is a common method of describing glass-ceramics. However, it can be clarified here that the glass ceramic of the invention is preferably obtained from a starting mixture of components comprising the glass ceramic in its oxide form.

In a preferred embodiment of the invention, the glass ceramic of the invention has a translucency of more than 75%, in particular more than 80%.

For determination of translucency, thin disks (1.5g, diameter >14mm) were pressed from ceramic powder and tested by firing in a dental oven. Subsequently, the final thickness of the disc was brought to 1.00. + -. 0.01mm by grinding and polished to a high gloss on both sides. The measurement was carried out in the visible range of the spectrum (360-740nm) using a commercially available spectrometer.

The glass ceramic according to the invention is distinguished by the fact that it forms a stable bond with the frame structure, so that chipping or damage under load (for example during chewing) is avoided, even with a low veneer thickness. In particular, this advantageous composite material is obtained because the coefficient of thermal expansion CTE of the glass ceramic is CTE matched to the coefficient of thermal expansion CTE of the material of the frame structure. The CTE of the glass-ceramic of the invention must not exceed that of the frame. It has been demonstrated that if the CTE of the glass ceramic of the invention is 0.1-2.5X 10 lower than the CTE of the frame structure^-6K^-1Is particularly advantageous. Thus, in a preferred embodiment, the glass-ceramic has a coefficient of thermal expansion CTE of less than 9.5 in a single component10^-6K^-1Preferably 9.3X 10 or less^-6K^-1More preferably less than 8.3X 10^-6K^-1-9.3*10^-6K^-1Or 8.3 x 10^-6K^-1-9.0*10^-6K^-1(measured using a dilatometer). The coefficient of thermal expansion is measured at 800 ℃ or below, in particular in the range of 100 ℃ and 400 ℃.

The glass ceramic of the invention is also characterized by a high chemical stability, which makes it particularly suitable for use in the dental field. Surprisingly, it was found that although B₂O₃High content, but the solubility of the glass-ceramics according to the invention is low, especially in acidic media. Thus, in a preferred embodiment, the glass-ceramic of the present invention has a solubility of less than 20. mu.g/cm²Preferably less than 10. mu.g/cm²More preferably 1 to 5. mu.g/cm². For example, the solubility can be determined according to DIN ISO 6872.

The glass-ceramic is preferably provided in the form of a powder, which is processed into a paste by using a liquid medium, which paste is then applied to the frame structure. It has surprisingly been found that the composite adhesion between the glass ceramic and the frame structure can be improved if a glass ceramic in powder form having a selected particle size distribution is used. Thus, in a preferred embodiment, the glass-ceramic is in the form of a powder having a particle size distribution D50 of 15 to 35 μm, preferably 20 to 25 μm, as determined by laser granulometry. Further preferably, the glass-ceramic of the invention is in the form of a powder having a particle size distribution D90 of 50-80 μm, preferably 60-75 μm, as determined by laser granulometry. In a preferred embodiment, the glass ceramic according to the invention is in the form of a powder with a particle size distribution D10 of 2 to 10 μm, preferably 3 to 5 μm, measured by means of a laser particle sizer.

In particular, it has been shown that adjusting the particle size distribution of the glass-ceramic according to the invention is an important factor in the formation of a stable bond between the frame structure and the glass-ceramic. For example, the particle size distribution may be obtained by subjecting the glass-ceramic to several grinding and melting processes during the preparation process. The invention therefore also relates to a process for preparing the glass ceramic according to the invention, comprising the following steps:

a) preparing a starting glass by melting a base component and quenching in water;

b) grinding the glass in step a) to obtain a powder;

c) pressing the powder of step b) to obtain a blank;

d) heat-treating the blank to obtain a glass-ceramic; and

e) grinding the blank in step d) to obtain a powder.

Preferably, in step a) of the process according to the invention, the preparation of the glass is effected by means of a starting mixture comprising the glass-ceramic components in their oxide form.

In a preferred embodiment of the invention, the production of the starting glass in step a) is carried out in two stages. Thus, in step a-i) a leucite partial frit powder capable of forming leucite crystals is first prepared. Preferably, said leucite partial frit powder is prepared by melting the basic components of the leucite partial frit, followed by quenching in water and optionally grinding the leucite partial frit thus obtained. Preferably, said leucite partial frit powder has the following composition:

50-60% by weight, preferably 52-58% by weight, of SiO₂；

12 to 18% by weight, preferably 13 to 17% by weight, of K₂O；

12 to 18% by weight, preferably 13 to 17% by weight, of Al₂O₃；

Optionally 4-10% by weight, preferably 5-9% by weight of Na₂O；

Optionally 1.5-6% by weight, preferably 2-5% by weight, of B₂O₃；

Optionally 0.5-3 wt%, preferably 1.0-2.5 wt% CaO; and

optionally from 0 to 2% by weight, preferably from 0.5 to 1.6% by weight, of Li₂O。

Further, in step a-ii) a glass partial frit powder is prepared, which is amorphous. Preferably, the glass partial frit powder is prepared by melting the basic components of the glass partial frit, followed by quenching in water and optionally grinding the glass partial frit thus obtained. The composition of the glass fraction frit is chosen so that, after mixing with the leucite fraction frit from steps a-i), a composition of the glass-ceramic of the invention is obtained. Preferably, the glass part frit powder has the following composition:

65-80% by weight, preferably 68-75% by weight, of SiO₂；

4-10% by weight, preferably 5-9% by weight, of K₂O；

2-10% by weight, preferably 3-9% by weight, of Al₂O₃；

Optionally 4-10% by weight, preferably 5-8% by weight of Na₂O；

Optionally 5 to 12% by weight, preferably 6.5 to 10% by weight, of B₂O₃；

Optionally 0.5-3 wt%, preferably 1.0-2.5 wt% CaO; and

optionally from 0 to 2% by weight, preferably from 0.5 to 1.6% by weight, of Li₂O。

Subsequently, the powders obtained from a-i) and a-ii) can be mixed in suitable mixing ratios. The mixing ratio of the leucite partial frit powder to the glass partial frit powder is selected to obtain the composition of the glass-ceramic of the present invention. Typically, the weight ratio of leucite partial frit powder to glass partial frit powder is from 1:20 to 1:1, preferably from 1:10 to 1: 2.

Subsequently, the powder mixture is subjected to further processing according to steps c) to e). Preferably, the heat treatment in step d) results in the formation of leucite crystals.

The heat treatment for forming the glass-ceramic in step d) of the method of the invention is preferably carried out at a temperature of 800-.

The glass ceramic of the invention is particularly suitable for being prepared into a veneer structure applied to a framework structure to obtain a dental restoration. The invention therefore further relates to the use of the glass ceramic according to the invention for facing frame structures, preferably lithium disilicate or ZrO₂Application in the veneering of a base ceramic frame structure.

In order to achieve a stable bond between the facing structure and the frame structure, it has proved advantageous if the facing structure and the frame structure have similar coefficients of thermal expansion. Thus, in a preferred embodiment, the facing structure has a coefficient of thermal expansion CTE_VSCoefficient of thermal expansion CTE with frame structure_FSThe difference is not more than 2.5 x 10^-6K^-1Preferably less than 1.5X 10^-6K^-1More preferably less than 1.0X 10^-6K^-1Wherein the frame structure has a higher CTE than the overlay structure, the coefficient of thermal expansion can be separately measured using an expansion meter.

The invention also relates to a dental restoration comprising a framework structure and a veneer structure, wherein the veneer structure is the glass ceramic of the invention. The framework structure is preferably lithium disilicate or ZrO₂A base ceramic frame structure. The framework structure can be designed to reproduce the natural color gradient of the tooth. This avoids complex colouring of the overlay structure. The coloring of the frame structure can be achieved, for example, by introducing a coloring oxide, or by using a coloring liquid. It was surprisingly found that the optical properties of the frame were not affected by the fired overlay structure. Thus, embodiments are preferred in which the frame structure has a color gradient. Alternatively, embodiments are preferred in which the frame structure is colored.

It has surprisingly been found that a stable bond between the facing structure and the frame structure can be achieved by means of the glass ceramic according to the invention even with thin facing structures. Thus, in a preferred embodiment, the thickness of the surfacing structure is from 0.2 to 3mm, preferably from 0.5 to 1.5 mm.

In order to achieve such a low thickness, it has proven advantageous to apply the facing structure in the form of a paste to the frame structure. The invention therefore further relates to a paste comprising a liquid medium and the glass ceramic of the invention. Preferably, the liquid medium is water, which may optionally contain other components.

The invention also relates to a method for producing a dental restoration, wherein a glass ceramic according to the invention or a paste according to the invention is applied to a framework structure. In a preferred embodiment, theThe frame structure is a ceramic frame structure, especially lithium disilicate or ZrO₂A base ceramic frame structure.

The invention is further explained by the following examples, which are in no way to be construed as limiting the basic idea of the invention.

FIG. 1 is an SEM micrograph of a glass-ceramic in example II of the present invention. The glass ceramic was treated with 5% HF for 90 seconds. The etched spots indicate where leucite is present.

Examples