KR102246214B1 - Radiopaque glass and use thereof - Google Patents

Abstract

The present invention relates to a radiopaque glass having a refractive index (n _d ) of 1.480 to 1.561, and the glass does not contain SrO and PbO other than only impurities. The glass is based on SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ systems. Radiopacity is adjusted using _{Cs 2} O, optionally in combination with fluorine, in particular BaO and/or SnO _2. The glass can in particular be used as a dental glass or as an optical glass.

Description

Radiopaque glass and its use {RADIOPAQUE GLASS AND USE THEREOF}

The present invention relates to lead-free radiopaque glasses and uses thereof.

In the dental field, polymer-based dental compositions are increasingly used for dental restorations. Such polymer-based dental compositions have conventionally consisted of a matrix of organic resins and various inorganic fillers. Inorganic fillers consist primarily of glass, (glass-)ceramics, quartz or other crystalline materials (e.g. YbF ₃ ), sol-gel materials and/or powders of aerosols, and are added as fillers to polymer-based compositions. .

The purpose of using a polymer-based dental composition is to prevent possible harmful side effects of amalgam and to improve esthetics. Depending on the polymer-based dental composition selected, it can be used, for example, for dental fillings or inlays, onlays, etc., and also for various dental repair measures with respect to crowns and bridges.

Such fillers are intended to minimize shrinkage resulting from polymerization of the resin matrix upon curing, and at the same time increase wear resistance. For example, if there is a strong adhesion between the tooth wall and the filling, excessive polymerization shrinkage can cause cracking of the tooth wall. If the adhesion is not sufficient for this purpose, excessive polymerization shrinkage can lead to the formation of a marginal gap between the tooth wall and the filling, which can promote secondary caries.

In addition, certain physical and chemical requirements are imposed on the filler:

The filler material must be able to be processed to produce a very fine powder. The finer the powder, the more homogeneous the appearance of the filling. At the same time, there is an improvement in the polishing properties of the filler, which leads to improved abrasion resistance through a reduction in the open surface area that can penetrate, which allows the filler to maintain its durability for a longer period of time. As described above, the powder is easy to process, and it is preferable that the powder does not undergo agglomeration.

In addition, it is advantageous if the filler is coated with a functionalized silane, since this promotes the formulation of the dental composition and improves the mechanical properties. The surface of the filler particles is at least partially covered with a conventionally functionalized silane.

Regarding its transparency and, where appropriate, the refractive index, the dental glass filler should fit as closely as possible with the resin matrix. In addition, throughout its entirety in which the filler material is also included, the polymer-based dental composition is aesthetically well applied to the natural dental material so that it is as indistinguishable as possible from the surrounding healthy dental material. Powdered fillers of very small particle sizes can likewise play a role in terms of aesthetic standards.

The effective chemical resistance of the filling, in particular with respect to water, can also contribute to the long life of the dental restoration means.

In addition, it is absolutely essential for the treatment of the patient that the means of tooth restoration can be seen on the X-ray image. Since the resin matrix is generally not visible in the X-ray image, the filler must ensure the necessary X-ray absorption. This kind of filler, which provides adequate absorption of X-rays, is said to be radiopaque. The components of the filler are related to radiopacity, examples being glass, or certain components of additives. These additives are also referred to as radiopaque agents. A conventional radiopaque agent other than dental glass filler is YbF ₃ , which can be added in crystalline pulverized form. These additives are also referred to as radiopaque agents. In addition to the dental glass filler, the conventional radiopaque agent is YbF ₃ , which may be added in a crystalline finely divided form.

According to DIN ISO 4049, the radiopacity of dental glass or dental material is recorded as aluminum equivalent thickness (ALET) in relation to the absorption of aluminum X-rays. The relative ALET is based on a sample thickness of 2 mm. Thus, a relative ALET of 200% means that a glass plate having a parallel planar surface having a thickness of 2 mm causes the same attenuation of X-rays as an aluminum plate having a thickness of 4 mm. Similarly, a relative ALET of 500% means that a glass plate with a parallel planar surface of 2 mm in thickness causes the same attenuation of X-rays as an aluminum plate of 10 mm thickness. In the following, the radiopacity of the glass is reported in terms of relative ALET (unit %).

Since polymer-based dental compositions in the application are conventionally injected from the cartridge into the pores, when modeled, they are often intended to be thixotropic in the uncured state. It decreases its viscosity when pressure is applied, while without exposure to pressure it is dimensionally stable.

In terms of filling materials, inert compositions are distinct from reactive dental compositions. The reactive dental composition includes dental cement. In the case of dental cement, an example is glass ionomer cement, the chemical reaction of the filler and the organic acid causes the curing of the dental composition, and the curing properties of the dental composition and its workability accordingly affect the reactivity of the filler. Receive. The process related to the present application is usually one of the settings that can proceed, for example, by superficial radical curing under the action of ultraviolet rays. The glass herein may act as a filler that causes or participates in a chemical reaction, or as an inert additive that does not participate in the reaction. In this case, the chemical reaction is likewise determined by the additional fillers present in the glass ionomer cement.

Apart from purely inert fillers and purely reactive fillers, there are various intermediate steps, which would not be able to be listed in detail. As examples of intermediate steps, mention may be made of “compomer” and “resin modified glass ionomer cement” (RMGIC).

Composites, also referred to as filler composites, while in chemical terms contain additional fillers, which are usually inert, whose curing properties are determined by the composition of the resin matrix and are therefore initially determined, and the chemical reaction of the fillers and/or additives. Is usually not preferred here.

Because, based on their different composition, glass represents a class of materials with various properties, it is often used as a filler for polymer-based dental compositions. Applications other than dental materials in pure form or as a component of a mixture of substances are also conservative and/or protective, for example inlays, onlays, and also shapes for crowns and bridges, materials for artificial teeth or prostheses. It may be possible to relate to materials for dental treatment. In these applications, such as dental materials, these glasses are generally referred to as dental glass.

In addition to those described above, another desirable property of dental glass is that it does not contain toxic lead oxide (PbO).

Thus, dental glass represents a particularly high grade glass. Such glasses can likewise be used in optical applications, in particular those that are advantageous due to the radiopacity of the glass. Since radiopacity means that the glass absorbs electromagnetic radiation in the region of the X-ray spectrum, this glass is meant to be a filter for X-radiation at the same time. Sensitive electronic components can be damaged by X-radiation. In the case of electronic image sensors, for example, the passage of both X-rays can damage the area of the sensor or undesired which may be received, for example, image interference and/or noisy pixels. Can cause a signal. Thus, for certain applications, it is necessary or at least advantageous for electronic components to be protected from X-radiation by filtering this radiation from the spectrum of incident radiation using the glass in question.

Numerous dental glasses and other optical glasses having similar optical positions or similar chemical compositions have been described in the prior art, but such glasses present significant drawbacks in manufacture and/or in use. In particular, many glasses contain significant proportions of fluoride and/or Li ₂ O, which evaporate very easily in the process of melting and fusing, thereby complicating the precise establishment of the glass composition.

Chemically inert barium-free dental glasses for use as fillers in composites are the subject of DE 198 49 388 A1. In the case of low index glasses, the glasses presented here necessarily contain a proportion of ZnO and F. The proportion of F can cause a reaction with the resin matrix, which in turn can be important for its polymerization behavior. In addition, the SiO ₂ ratio to 20-45% by weight limits that the glass described contains sufficient radiopaque agents and F. In particular, for low ZnO and ZrO ₂ content, the addition of up to 27% by weight of SrO is recommended.

WO2005/060921 A1 describes glass fillers that are particularly suitable for dental composites. It contains 9 to 20 mol% of an alkali metal oxide. The purpose of this specification is to provide a glass particle whose concentration of alkali metal ions is lower at the edge of the particle than at its center. This is because the described glass has intentional chemical instability, otherwise this concentration behavior cannot be achieved. It can be assumed that essentially low chemical stability is achieved by the stated proportions of the alkali metals in the initial glass.

Alkali metal silicate glasses serving as fillers for dental materials are described in EP 0885606 B1. In a _{glass with a high SiO 2 content, an Al 2} O ₃ ratio of 5% by weight or more increases the viscosity, resulting in a very high melting temperature. Sodium oxide and potassium oxide are included as essential components. In addition, glass does not contain a substance that imparts radiopacity.

DE 4443173 A1 comprises a high zirconium content barium-free glass with a _{ZrO 2} content higher than 12% by weight and other oxides. Such fillers are particularly too reactive for current dental compositions based on acrylates, which can cause uncontrolled curing, for example excessively rapidly. Zirconium oxide in this amount has a tendency to devitrification. This possibly leads to phase separation with nucleation and subsequent crystallization. In addition, such glasses can be produced with high alkali metal content, thereby ensuring that the melting temperature is not too high, which makes melting aggregation difficult. However, after all, this high content of alkali metal is detrimental to the chemical stability of the glass.

DE 199 45 517 A1 likewise describes a glass of high zirconium content which exhibits the same problems as the glass in the above specification in applications in the dental field.

DE 10 2005 051 387 B3 is a dental glass, a magnesium alumino having a high content of _{La 2} O ₃ and/or Y ₂ O ₃ and also WO ₃ and ZrO ₂ to achieve radiopacity and a refractive index of 1.50 to 1.549. Describes silicate glass. These glasses do not contain barium, strontium and alkali metal oxides. In view of the high magnesium oxide content of these glasses, it has a tendency to phase separation. Another disadvantage is the high sensitivity to crystallization due to the content _{of WO 3} and ZrO _2. This content additionally raises the melting temperature. La ₂ O ₃ is a very expensive raw material and should be avoided accordingly.

DE 10 2009 008 951 A1 discloses radiopaque, barium-free glasses containing essentially zirconium oxide and their use as dental glasses. To achieve a narrow refractive index range of 1.518 to 1.533, ZrO ₂ is used with Cs ₂ O and/or La ₂ O ₃ . In order for this glass to be melted, a high K ₂ O ratio is also required. Likewise, here a problem with such glass is the tendency of crystallization combined with the relatively high melting temperature and the raw material cost caused by the _{La 2} O _{3 used.} Glass with a low refractive index is not described in the prior art.

DE 10 2011 084 501 B3 discloses a barium-free, radiopaque glass having a refractive index of 1.50 to 1.58. Glass is based on a combination of SrO and La ₂ O ₃ and ZrO _{2 as radiopaque agents.} In addition, Cs ₂ O may be added to increase radiopacity. The advantage of these glasses is their high melting temperature and tendency to crystallize. The La ₂ O ₃ described above is very expensive.

JP 2004-002062 A is a glass substrate for flat screens. In addition to SrO, the disclosed glasses mainly contain BaO and also a high proportion of Al ₂ O ₃ and MgO. Al ₂ O ₃ , SrO, BaO and MgO components are required as a network transformer to ensure the meltability of the glass. These glasses are also not considered to be used as dental glasses, because they considerably lack the required radiopacity. Separately, the content of Al ₂ O ₃ has a high SiO _{2 -} and to increase the viscosity of the content of the glass, and thus require a high melting temperature for the purposes of manufacture accordingly. The high content of MgO is a disadvantage in glass for dental applications, which is intended to have a low refractive index combined with high radiopacity. MgO does not increase the radiopacity to the same extent as other alkaline earth metal oxides CaO, SrO and BaO, instead of primarily exhibiting an increase in the refractive index (n _{d ), and thus it creates a desirable balance between low refractive index and high radiopacity.} It can be complicated.

A feature shared by all glasses identified in the prior art is that they have low hydrolysis resistance or are too reactive and/or are not radiopaque, or they contain components that are harmful to health and/or the environment. In addition, many known dental glasses contain SrO, which significantly increases the melting temperature. In addition to these economic disadvantages, the high SrO ratio makes it difficult to control the crystallization operation during the manufacturing process of many glasses. Also, with known radiopaque agents used alone or in known combinations (usually in combination _{with La 2} O ₃ ), the achievable radiopacity cannot be increased arbitrarily and satisfactorily without too large an increase in the refractive index. . Glass with a refractive index greater than 1.65 (as described in WO 2007/034258 A1, for example) cannot currently be used satisfactorily in practice as dental glass, fillers for polymer-based dental compositions, and the like. In addition, the disadvantage of lanthanum oxide is that it is too expensive and impairs the economics of the glass produced using it.

It is an object of the present invention to provide a relatively low refractive index lead-free, radiopaque glass having improved radiopacity.

In particular, it is also an object of the present invention to provide a glass system capable of producing a glass having a more easily improved radiopacity in relation to the refractive index and refractive index precisely defined within a given refractive index range, for improved ease of manufacture. Is to provide. The glass is preferably suitable for use in the field of dentistry as a medical part, in particular as a dental glass, and as an optical glass. It must be reasonably producible, biocompatible despite its high grade, and also suitable for passive and active dental protection, processability, setting behavior of the surrounding polymer matrix, and also long-term stability and strength. It should have excellent properties in relation to it. In order to meet the requirements in modern dental treatment and dental technology, in addition, the glass of the present invention must have at least good hydrolytic stability.

The drawings show:
1 is a correlation between the refractive index and the relative aluminum equivalent thickness for the example in Table 1,
2 is a correlation between the refractive index and the relative aluminum equivalent thickness for the example of Table 1 with advantageous upper and lower limits,
3 is a correlation between the refractive index and the relative aluminum equivalent thickness for the example of Table G 1500 with advantageous upper and lower limits,
Figure 4 is a correlation between the refractive index and the relative aluminum equivalent thickness for the example of Table G 1515 with advantageous upper and lower limits,
5 is a correlation between the refractive index and the relative aluminum equivalent thickness for the examples of Table G 1525 with advantageous upper and lower limits,
6 is a correlation between the refractive index and the relative aluminum equivalent thickness for the example of Table G 1550 with advantageous upper and lower limits.

The glass according to the invention in the base matrix should also not contain coloring components such as Fe ₂ O ₃ , CoO, NiO, CuO, etc., other than only impurities or influents and/or residual components that are difficult to avoid in industrial production, thereby coloring teeth. It allows the selection of the optimal starting coloration location for possible applications for and/or for optical applications, adaptation of the spectrum of the passing electromagnetic radiation is possible. In addition, the glass should not contain colored particles that cause a second glass phase and/or scatter and similarly alter the perceived color. One or more additional glass phases will reduce the resistance of the glass.

This object is achieved by a glass according to the independent claim. Preferred embodiments and applications are apparent from the dependent claims.

_{In particular, there is provided a radiopaque glass having a refractive index (n d} ) of 1.480 to 1.561, which does not contain PbO except only impurities, which includes (in weight percent on an oxide basis):

Cs ₂ O is always present in glass as a radiopaque agent. In an advantageous embodiment, this ensures a high radiopacity of the glass in combination with one or more additional radiopaque agents. Particularly advantageous variants include Cs ₂ O and at least BaO or SnO ₂ as radiopaque agents, where La ₂ O ₃ may also optionally be included. Advantageous SnO ₂ -containing radiopaque agents include _{SnO 2} in addition to Cs ₂ O and BaO, _{optionally with La 2} O _{3. A further advantageous embodiment includes a combination of Cs 2} O and La ₂ O ₃ serving as a radiopaque agent, wherein an advantageous variant of this embodiment may not contain BaO.

Some advantageous variants of the radiopaque glass mentioned may include fluorine (fluorine-containing variant). The component fluorine can be included to better adjust the refractive index depending on the radiopaque agent used. When fluorine is included, the content may advantageously be 0.3% by weight or more and 0.5% by weight or more. A preferred upper limit may be 6% by weight, advantageously 5.5% by weight, preferably 2.5% by weight. Another advantageous variant has a significantly reduced fluorine content in the range of 0 to less than 0.3% by weight, i.e., this variant may be fluorine deficient (fluorine-deficient variant) or even fluorine free ( Fluorine-free variant).

_{An advantageous fluorine-containing embodiment of the present invention is a radiopaque glass having a refractive index (n d} ) of 1.480 to 1.561, which does not contain PbO other than only impurities, including the following.

For the purposes of the present invention, advantageous sub-variants of the fluorine-containing variant are possible, ie the advantageous SnO ₂ -containing sub-variants and the advantageous SnO ₂ -free sub-variants. The SnO ₂ in an amount of 15% by weight beneficial SnO _2-contained sub-variant is advantageously greater than 0 - 15% by weight, preferably 0.3 - 15 wt.% Or 0.5 - 15% by weight, more advantageously 1 Includes. Another advantageous SnO ₂ content is greater than 4-15% by weight. Alternatively, the fluorine-containing radiopaque glass can advantageously be SnO ₂ -free (SnO ₂ free sub-variant).

An advantageous fluorine-reducing embodiment of the present invention (fluorine-deficient or fluorine-free variant) is a radiopaque glass having _{a refractive index (n d) of 1.480 to 1.561, which does not contain PbO except only impurities, which is (} In weight percent on an oxide basis) including:

For the purposes of the present invention, advantageous sub-modifications of the fluorine-reducing variant are possible, ie the advantageous SnO ₂ -containing sub-modification and the advantageous SnO ₂ -free sub-modification. Advantageous SnO _2-contained sub-variant is advantageously greater than 0 - 15% by weight, preferably 0.3 - 15 wt.% Or 0.5 - 15% by weight, more advantageously from 1 to - a SnO ₂ content of 15% by weight Includes. Another advantageous SnO ₂ content is greater than 4-15% by weight. Alternatively, the fluorine-deficient and/or fluorine-free radiopaque glass can advantageously be SnO ₂ -free (SnO ₂ free sub-variant).

The glass according to the invention has a refractive index n _d (also referred to as the refractive index) of 1.480 to 1.561. Thus, it applies very well to dental polymers and/or acrylate-based resins available within this refractive index range, whereby the aesthetic requirements imposed on polymer-based dental compositions, in particular dental glass/polymer composites, are natural. Satisfied for the appearance.

The glass according to the present invention achieves the properties of lead-containing dental glass related to the required X-ray absorption without the use of lead or other substances that may be rejected for health reasons. The glass according to the invention does not contain lead. The term "free" in this context means the absence of such substances other than for example only unavoidable contaminants which may be caused by air pollution and/or impurities in the raw materials used. However, also especially for dental glass, contamination of the glass with unwanted substances generally _{does not exceed 300 ppm for Fe 2} O ₃ , preferably not more than 100 ppm, and 30 ppm for PbO, As ₂ for O ₃ it does not exceed 100 ppm about 20 ppm, other impurities about 20 ppm, Sb ₂ O _3. SrO is always closely related to BaO in the raw material. Depending on the purity of the BaO raw material, up to 0.7% by weight of SrO may be present in the glass according to the invention. These limit values are covered by the phrase "excludes impurities only, does not contain them". Of course, the complete absence of the aforementioned undesired substances from the glass according to the invention is particularly preferred. The SrO component is preferably not actively added to the glass according to the invention.

X-ray absorption and thus radiopacity are advantageously achieved through a combination of radiopaque agents.

According to an advantageous variant of the invention, the radiopacity _{is by a combination of Cs 2} O, BaO and/or SnO ₂ , i.e. through the presence of two or more of these components, advantageously preventing the presence of these three components. Is achieved through Unlike early dental glasses that were attempted to achieve radiopacity through a high content of usually possible one high absorption component or through _{a combination with La 2} O _{3, radiopacity according to this variant of the present invention} Silver is achieved by a suitable combination of two or more of these BaO, SnO ₂ and/or Cs _{2 O components effective in radiopacity.} In this way, it is possible to achieve particularly stringent requirements for the optical properties of the glass, and also to achieve very good hydrolysis and/or chemical resistance. The content for BaO, SnO ₂ and Cs ₂ O as a whole is preferably at least 8% by weight, more preferably at least 10% by weight, and most preferably at least 12% by weight. Very little of these components cause insufficient X-ray absorption. The higher the sum of these radiopaque agents in the glass, the higher the radiopacity. The advantageous upper limit for the sum of BaO, SnO ₂ and Cs ₂ O is 51% by weight, preferably 49% by weight, more preferably 47% by weight, also preferably 45% by weight, further preferably 43% by weight. Can be

Further, with regard to the advantageous fluorine-containing variant, the radiopaque glass contains a limited amount of fluorine, which serves to specifically adjust the refractive index of the glass according to the specific amount of the radiopaque agent. This corresponds to the effect as a result of the use of a large amount of radiopaque agents in the glass, the radiopacity actually increases, but at the same time the refractive index of the resulting glass also increases. Through the addition of fluorine, it is possible to keep an increase in the refractive index within a limit value or even prevent an increase in the refractive index.

The combination of the radiopaque components BaO, Cs ₂ O, and/or SnO ₂ with optionally F has surprisingly proved to be particularly suitable for producing glasses with high radiopacity in a relatively wide refractive index range of 1.480 to 1.561. _{In the context of the present invention, it is supplied for this purpose so that the sum of BaO, Cs 2} O, SnO ₂ and F in weight percent based on the oxide is at least 8% by weight or at least 9% by weight, preferably at least 10% by weight . Advantageously, the sum may be at least 11% by weight or at least 12% by weight, some advantageous variants may be at least 13% by weight or at least 14% by weight, and other advantageous variants may be at least 15% by weight or It may be at least 16% by weight or at least 17% by weight. The advantageous upper limit of the sum of BaO, Cs ₂ O, SnO ₂ and F is 56% by weight, preferably 54% by weight, more preferably 52% by weight, also preferably 50% by weight, further preferably 48% by weight It can be %. Some advantageous variants may have an upper limit of 42% or 36% or 35% by weight relative to the total. It is generally known that glass with a lower index of refraction tends to achieve a lower radiopacity and thus a lower value of aluminum equivalent thickness than glass with a higher index of refraction. The reason for this is that only a relatively small amount of radiopaque agent can be used for low refractive index glass. If the proportion of radiopaque agent is increased, the refractive index will shift to a higher value. Through the advantageous combination of BaO, Cs ₂ O, and SnO ₂ in particular F, it is possible to change the radiopacity and corresponding aluminum equivalent thickness to higher values than the entire refractive index range of the present invention. This makes it possible to achieve substantially higher X-ray visibility values than is possible heretofore for a given index of refraction. It is also possible to specifically adjust the refractive index in radiopaque glass.

Particularly advantageous embodiments of radiopaque glasses with advantageous combinations of fluorine and three radiopaque agents include:

In general, the present invention has succeeded in providing a glass system capable of accurately adjusting the refractive index of the glass to specific requirements by changing the ratio of the components in the system described above, wherein the glass has improved radiopacity for a given refractive index. This simplifies the manufacture of glass with high radiopacity that refracts differently.

The following glass components are described for all glasses according to the invention and advantageous variants.

_{Basically, the glass according to the invention comprises SiO 2} as a glass-forming component in a proportion of 35 to 75% by weight. The upper limit according to the invention is 75% by weight. Higher content of SiO ₂ can unfavorably lead to high melting temperatures, whereas, in addition, the required radiopacity cannot be achieved. In the case of an advantageous embodiment, 73% by weight, preferably 70% by weight, more preferably 68.5% by weight or 65% by weight can be selected as the upper limit of _{SiO 2. Some advantageous variants have a SiO 2} upper limit of 64% by weight, advantageously 61% or 59% or 56% or 53% by weight. According to the invention, the lower limit is 35% by weight. Lower content can have negative consequences for chemical resistance and devitrification tendency. In the case of an advantageous glass composition, the _{lower limit of SiO 2} may be 36% by weight, preferably 37% by weight, more preferably 38% by weight, further preferably 39% by weight. Some advantageous variants may comprise at least 40% by weight, preferably at least 42% or at least 45% or at least 47% or at least 50% by weight of SiO ₂ . One preferred embodiment of the glass according to the invention is envisioned with _{a SiO 2} content of 38 to 70% by weight, more preferably 39 to 70% by weight.

B ₂ O ₃ is provided to the glass according to the invention in a content of 2 to 16% by weight, advantageously 4 to 15% by weight, preferably 5 to 15% by weight. It can advantageously be provided in the range of 6 to 15% by weight or 7 to 15% by weight. Some advantageous variants include 3 to 14% by weight of these components. B ₂ O ₃ has a positive effect on glass formation and melting behavior. It also acts as a flux. In addition to the lowering effect on the melting temperature, _{the use of B 2} O ₃ simultaneously leads to an improvement in the crystallization stability of the glass according to the invention. Thus, according to the invention, the lower limit is 2% by weight. For certain glasses, 3% or 4% by weight, advantageously 5% by weight, preferably 6% by weight, preferably 7% by weight, can also be selected as an advantageous lower limit for boron oxide. The upper limit for boron oxide according to the invention is 16% by weight, preferably 15% by weight. Higher ratios are not recommended for these systems in order not to impair chemical resistance. Up to 14.5% by weight, preferably up to 14% by weight of boron oxide can also be advantageously included. If _{the content of B 2} O ₃ is too high, the case of separation from the glass may occur, which in turn shows an undesired non-uniformity of the refractive index, and also has a side effect on chemical resistance.

The glass according to the invention essentially comprises Al ₂ O ₃ in the range of 0.8 to 7.5% by weight. It may advantageously be present in the range of 0.8 to 6% by weight or 1 to 7% by weight. Al ₂ O ₃ improves the chemical resistance of glass. Thus, according to the invention, in the glass it is present in an amount of at least 0.8% by weight. Aluminum oxide of at least 1% by weight, preferably at least 1.2% by weight, can also be used advantageously. _{However, the Al 2} O ₃ content of approximately 7.5% by weight should not be exceeded so that the glass is difficult to melt-especially in hot processing parts-so that the viscosity of the glass does not increase. In addition, an excessively large amount of aluminum oxide impairs the tendency to devitrify and also the resistance of the glass to acids. The upper limit of Al ₂ O ₃ is preferably 7% by weight, more preferably in fact only 6.5% by weight or 6% by weight.

Alkali metal oxides from the group of Li ₂ O, Na ₂ O and K ₂ O are required in order to allow the glass to melt at all. K ₂ O acts to adjust the melting temperature and at the same time strengthens the glass network. Thus, according to the invention, it is present in the glass composition in a proportion of 0 to 14% by weight, advantageously 0 to 12% by weight, preferably 0 to 10% by weight. For K ₂ O, a range of 0 to 7% by weight is preferred, and a range of 0 to 5% by weight is particularly preferred for some advantageous variants. _{This is because the upper limit of 14% by weight for K 2} O according to the present invention should not be exceeded, and the content of the alkali metal oxide lowers the chemical resistance. Further, advantageously, 12% by weight or 11% by weight, preferably 10% by weight, preferably 7% by weight, preferably 6% by weight may be selected as the upper limit. A particularly advantageous variant comprises up to 5% by weight, more preferably up to 4% by weight K ₂ O. For some advantageous variants _{, the advantageous lower limit for K 2} O may be 0.5% by weight, 1% by weight, 1.5% by weight or 2% by weight. Also, _{embodiments that do not contain K 2} O are possible for the purposes of the present invention.

The sodium ions and lithium ions have a small size that allows them to more easily leach out of the glass matrix, thereby reducing chemical resistance, especially hydrolysis resistance. In one advantageous embodiment of the invention, the radiopaque glass does not contain _{Na 2} O and/or Li _{2 O other than only impurities.}

Impurities can be introduced into the glass by contamination of the raw materials used for making the glass, and/or by contamination and/or corrosion of the melt aggregates used. These impurities generally do not exceed a proportion of 0.2% by weight, in particular 0.1% by weight. Of course, this also includes the complete absence of the ingredients being discussed. Thus, "component free" means that the glass is essentially free of such components, ie, any such component is present as an impurity, even if it is present in the glass, but is not added as an individual component to the glass composition. .

The content of barium oxide is 0 to 24% by weight, preferably 0.6 to 24% by weight. The preferred range is 0.8 to 20% by weight, more preferably 1 to 18.5% by weight for some variants. A too high amount of BaO causes a decrease in chemical resistance. Therefore, the upper limit of 24% by weight should not be exceeded. For some variants, it is also possible to select as an upper limit, advantageously 22% by weight, or 21% by weight, more advantageously 20% by weight, preferably 18.5% by weight or 18% by weight. Further advantageous upper limits may be 17%, 15%, 14%, 12% or 10% by weight. In an advantageous variant, there should be at least 0.6% by weight of BaO present in the glass in order to achieve X-ray absorption with other materials. BaO may advantageously be present in the glass in an amount of at least 0.8% by weight, preferably at least 1% by weight, more preferably at least 1.1% by weight. Some advantageous variants may have a lower limit of BaO of 2%, 4% or 6% by weight. However, BaO-free radiopaque glass variants are also possible in the context of the invention described below.

Advantageous embodiments of the radiopaque glass may not contain BaO. In such glasses, the impermeability can only be based _{on Cs 2 O.} In order to produce higher X-ray absorption, La ₂ O ₃ and/or SnO ₂ can advantageously be used in the glass as radiopaque agent(s) other than the _{contained Cs 2 O. Advantageous variants of radiopaque glasses having a refractive index (n d} ) of 1.480 to 1.561 that do not contain PbO and BaO other than only impurities include (in weight percent on an oxide basis):

With regard to the BaO-free variant, the combination of components Cs ₂ O or Cs ₂ O and La ₂ O ₃ and/or SnO ₂ acting as radiopaque agents is used to produce the required radiopacity in the desired refractive index range. It can be enough. For glass in medical applications, especially in the dental field, the BaO-free variant is an advantageous alternative to the known BaO-containing and/or SrO-containing radiopaque glasses. Advantageously, the BaO-free variant also has a low fluorine content, in particular less than 2% by weight, preferably less than 1% by weight or less than 0.5% by weight or less than 0.3% by weight. Further, advantageous BaO-free variants may contain no fluorine.

_{Cs 2} O according to the invention is likewise used to achieve X-ray visibility, but at the same time also contributes to improving the meltability. According to the invention, Cs ₂ O is present in the glass composition in 1 to 30% by weight, preferably 1 to 28% by weight, more preferably 1.5 to 26% by weight, most preferably 2 to 25% by weight. The alkali metal Cs is more stationary in the glass matrix compared to the alkali metals Li, Na, K and Rb. Therefore, it is less severely leached, and the chemical resistance is less impaired than the aforementioned alkali metal. Since too little Cs ₂ O leads to poor X-ray visibility and increased melting temperature, the lower limit according to the invention is 1% by weight. In the case of advantageous glass compositions, the lower limit may also be 1.5% by weight, more advantageously 2% by weight, preferably 2.5% by weight, very preferably 3% by weight. Some advantageous variants may contain at least 5% by weight or at least 6% by weight or at least 7% by weight of Cs ₂ O. Another advantageous variant may have a lower limit of 9% or 10% by weight of Cs _{2 O.} This is because according to the present invention, the Cs ₂ O present must be 30% by weight or less, otherwise chemical resistance is impaired. Advantageously the glass composition contains up to 28% by weight of Cs ₂ O, preferably up to 26% by weight of Cs ₂ O, more preferably up to 25% by weight or up to 24% by weight of Cs ₂ O. Some advantageous variants may contain up to 22% by weight, preferably up to 20% by weight or up to 19% by weight of Cs ₂ O.

Advantageously, SnO ₂ likewise serves to adjust X-ray visibility. This contributes to high radiopacity, and the refractive index increases less strongly than other radiopaque agents. These components are present in the glass composition in a proportion of 1 to 15% by weight. Some advantageous variants of the glass according to the invention do not contain _{SnO 2.}

In the SnO ₂ -containing variant, SnO ₂ is 0.5 to 15% by weight, advantageously 1 to 15% by weight, advantageously 3 to 15% by weight, preferably 4 to 15% by weight, more preferably> 4 It is present in the glass composition in an advantageous proportion of from to 15% by weight, very preferably from 4 to 12% by weight and particularly preferably from 4 to 10% by weight. Too small amounts of SnO ₂ can lead to poor X-ray visibility, and thus these components may be at least 0.1% by weight or at least 0.3% by weight, advantageously at least 0.5% by weight or with respect to the _{advantageous SnO 2 -containing variant.} It should be present in an amount of 1% by weight or more. In addition, SnO ₂ improves and ensures the chemical resistance of Cs _{2 O-containing glass.} In addition, 3% by weight, preferably 4% by weight, more preferably> 4% by weight may be advantageously provided as the lower limit of _{SnO 2.} Very high amounts of SnO ₂ cause severe devitrification and/or a tendency to crystallize. Therefore, the upper limit of 15% by weight should not be exceeded. As an upper limit selected, advantageously 13% by weight, preferably 12% by weight, more preferably 10% by weight, very preferably also 9% by weight of SnO ₂ may be present. Variations with less SnO ₂ may have an advantageous upper limit of 6% or 3% by weight.

In the context of the advantageous fluorine-containing variant of the invention, the radiopaque glass contains fluorine in a proportion of at least 0.3% by weight, preferably 0.5% by weight. Advantageously up to 8% by weight, preferably up to 5.5% by weight, preferably up to 5% by weight or-in some variants-up to 2.5% by weight of fluorine is present. Some variations have an upper limit on F of 6% or 3% by weight. An advantageous range for F in an advantageous embodiment may also be 0.75 to 2.5% by weight, particularly advantageously 0.75 to 2.25% by weight, preferably 1 to 2% by weight. Fluorine herein is recorded in atomic form and is referred to as mass in the composition. This serves to adjust the refractive index by interaction with the above-described combinations of radiopaque agents, and improves the melting properties of the glass batch by lowering the melting temperature. Thus, it may be included in the composition at least 0.3% by weight, preferably at least 0.5% by weight. As well as 0.75% by weight, preferably 1% by weight can be selected as an advantageous lower limit. The upper limit of 8% by weight, advantageously 6% by weight, preferably 5.5% by weight, preferably 5% by weight should not be exceeded, otherwise the component may evaporate in the course of the melting operation, and the non-uniformity of the refractive index in the glass Because there can be one distribution. Fluorine may advantageously be present in a proportion of up to 2.5% by weight, preferably up to 2.25% by weight, more preferably up to 2% by weight in some variations.

In the fluorine-deficient variant of the present invention, less than 0.3% by weight of F is present. The fluorine-free variant does not contain F.

At this point, it is understood that any of the above-described upper and/or lower limits of one component can be arbitrarily combined with all of the aforementioned upper and/or lower limits of the other component, in a manner that is included in the present description and will be apparent to those skilled in the art. You will know.

In one advantageous embodiment of the glass of the corresponding variant comprising _{SnO 2 and F, the molar ratio of SnO 2} to F is at least 0.4, preferably at least 0.45, more preferably at least 0.49, very preferably at least 0.5. Is provided. In an advantageous embodiment _{, it is preferred that the molar ratio of SnO 2} to F is 0.85 or less, preferably 0.79 or less, more preferably 0.77 or less, further 0.75 or less, also preferably 0.72 or less, very preferably 0.7 or less. . Through these measurements, it is possible to accurately set the refractive index of the glass in combination with a relatively high X-ray absorption. A further advantage is that the correct ratio ensures the meltability of the glass. Values that are too high produce a non-uniform melt.

Additional radiopaque refractive index and radiopaque in a glass, that is, high aluminum to improve the adjustment of the equivalent thickness, Cs ₂ O for the above-described opaque task Cs ₂ O, more than a molar ratio of the sum of BaO and SnO ₂ 0.05, preferably in It is advantageous if it is 0.07 or more, more preferably 0.1 or more. It advantageously does not exceed an upper limit of 0.48, preferably 0.45 and more preferably 0.41. Too little a rain causes too low X-ray absorption. Too high a ratio reduces chemical resistance.

The radiopaque glass may optionally contain _{ZrO 2} in a proportion of 0 to 2% by weight, preferably 0 to 1% by weight. This zirconium content improves mechanical properties, in particular tensile and compressive strength, and also lowers the brittleness of the glass. However, too high a content can result in a glass that becomes highly reactive, especially in the environment of dental polymers. On the other hand, glass is at least almost usually inert to dental polymers, in particular composites, which, for example, do not interfere with their polymerization behavior. In one advantageous variant, the glass does not contain zirconium oxide (ZrO ₂ -free).

One advantageous embodiment of the radiopaque glass may include alkaline earth from the group of CaO and MgO in limited proportions. The proportion of CaO may be 0 to 2% by weight. MgO is likewise optional and can be present in 0 to 2% by weight. In one particular preferred embodiment, the glass according to the invention contains no MgO but only impurities. MgO can be detrimental to glass in dental applications where a low index of refraction is combined with high radiopacity. MgO does not increase the radiopacity to the same extent as other alkali earth metal oxides CaO, SrO and BaO, which means that the X-ray absorption edge of MgO is much below them, and that of tungsten X-ray tubes used in medical applications. This is because it shows only a small effect on the part. MgO only increases the refractive index, thereby complicating the balance between low refractive index and high radiopacity.

The glasses according to the invention are free of CeO ₂ and TiO ₂ , except optionally only impurities. Taking into account their absorption in the UV region, CeO ₂ and TiO ₂ shift the UV edge of the glass, which can result in unwanted yellowish coloring. In one preferred embodiment, the glass according to the invention does not contain _{TiO 2.}

One particularly preferred embodiment of the glass does not contain _{TiO 2} and ZrO _2.

Preferably, ZnO and/or WO ₃ and/or Nb ₂ O ₅ and/or HfO ₂ And/or Ta ₂ O ₅ and/or Gd ₂ O ₃ And/or Sc ₂ O ₃ and/or Y ₂ O ₃ and/or Yb ₂ O ₃ may additionally be present in 0 to 2% by weight, individually or in any combination.

In the context of the present invention, La ₂ O ₃ can advantageously be used in a proportion of 0 to 19% by weight, preferably 0 to 16% by weight or 0 to 15% by weight in order to adjust the desired radiopacity of the glass. . If La ₂ O ₃ is included, in general it will advantageously be present in the glass at least 0.1% by weight, preferably at least 0.2% by weight, preferably at least 0.5% by weight or at least 1% by weight. Preferably, the La ₂ O ₃ -containing glass comprises more than 2% by weight of this component. Some advantageous variants have a suitable lower limit of 4% by weight. An advantageous upper limit of La ₂ O ₃ may be 19% by weight or 18% by weight, preferably 17% by weight or 16% by weight or 15% by weight. Another advantageous variant may have a suitable upper limit for _{La 2} O ₃ of 13% or 11% or 10% or 9% or 8% or 7.5% or 6% or 5% by weight of La 2 O 3 by weight.

As an alternative to the La ₂ O ₃ -containing variant, the invention includes an advantageous variant with a significantly reduced content _{of La 2} O _3. This variant contains up to 2% by weight, preferably up to 1.5% by weight or up to 1% by weight of La ₂ O ₃ (La ₂ O ₃ -deficient variant). If La ₂ O ₃ is present in this variant, 0.1% by weight may be an advantageous lower limit for this. The _{limitation on the La 2} O ₃ content has an advantageous effect of not increasing the refractive index of the glass too much. One preferred embodiment of the glass does not contain _{La 2 O 3 (La 2 O} 3 - containing non-variant). This provides a cost advantage and enables the production of low-index glasses with high radiopacity.

It is possible for radiopaque glasses for industrial or optical applications to contain, for example, in a proportion of 0 to 2% by weight, advantageously 0 to 1% by weight, of one or more detergents selected from the group of chlorides or sulfates. SnO ₂ can also likewise be used as a cleaning agent with the advantages of possible cleaning agents, such as As ₂ O ₃ and Sb ₂ O ₃ , and also the above-mentioned chlorides and sulfates, contamination by other cleaning agents does not occur in the melt aggregate. This is advantageous when dental glass is likewise produced after industrial glass.

The linear coefficient of thermal expansion α(20-300) of the glass according to the invention, measured at a temperature interval of 20° C. to 300° C., is preferably less than ^{7×10 −6} K ^−1. As a result of the low coefficient of thermal expansion, the glass according to the invention is able to compensate for the inherent high thermal expansion of the polymer, especially when used as a filling material in a polymer, and is thus well suited to natural tooth materials in polymer-based dental compositions. The applied thermal expansion is given.

As previously described, the glasses according to the invention are resistant to chemical attack-that is, they are chemically stable. They preferably have water resistance HGB according to DIN ISO 719 of class 2 or better.

Thus, the glass according to the present invention is noted for its chemical resistance, which in combination with a resin matrix results in a high degree of inertness and thus a very long life of the dental composition as a whole.

According to a further preferred embodiment of the invention, the glass according to the invention also preferably does not contain other components mentioned in the claims and/or in the description. This means that according to one such embodiment, the glass consists substantially of the above-described components. The expression “consisting substantially of” herein means that other components are present as impurities when present, but are not intentionally added as individual components to the glass composition.

Nevertheless, the invention also envisions the use of the glass according to the invention as a basis for further glasses, in which up to 5% by weight of additional components can be added to the glass according to the invention described. In this case, the glass consists of the glass described above according to the invention in the range of at least 95% by weight.

Of course, it is also possible to apply the colored appearance of the glass for optical or other industrial applications through the addition of conventional oxides for the purpose. Suitable oxides for coloring glass are known to the person skilled in the art, examples of which include CuO and CoO, which for this purpose can preferably be added in an amount of 0 to 0.5% by weight. In addition, the glass may be given a preservative function through the addition _{of Ag 2} O in an amount of, for example, 0 to 3% by weight.

The invention further encompasses a glass powder composed of the glass according to the invention, and the use of the radiopaque glass according to the invention as a glass powder. Glass powders are prepared, for example, by the known method described in DE 41 00 604 C1. The glass powder and/or powder particles according to the invention preferably have an average particle size of at most 50 μm, more preferably at most 20 μm. An average particle size of 0.1 μm can reach the lower limit, but of course smaller particle sizes are also included in the present invention. The glass powders described above can generally serve as fillers and/or as starting materials for the use of the glass according to the invention as dental glass. The radiopaque glass according to the invention provides an advantageous use in a dental glass/polymer dental composition comprising a dental polymer. Dental compositions of this kind may be, for example, dental filling materials, inlays, onlays, materials for dental cement, shape materials for crowns and bridges, materials for artificial teeth, and/or for prosthetics, conservative and/or Or as other materials for protective dental treatment are found.

In one preferred embodiment, the surface of the glass powder, ie the surface of the glass powder particles, is silanized by conventional techniques. Silanization makes it possible to improve the bonding of the inorganic filler to the polymer matrix of the polymer-based dental composition.

The initially stated object is further achieved by the radiopaque glass according to the invention for use in the medical field, more particularly in the dental medicine field, as dental glass and/or for diagnostic purposes. Diagnostic purposes include medical applications, examples of which are use in contrast media.

In addition, the initially stated object is achieved by a radiopaque glass according to the invention for use as dental glass for treatment of voids in human and/or animal teeth and/or for tooth restoration. Treatment generally involves complete or partial filling of voids, hollows, gaps, etc. in the tooth.

The glass according to the invention can preferably be used as described as dental glass. In this case, it is advantageous if the dental glass is in the form of powder particles. This is further advantageous when it is a component of a polymer-based dental composition comprising a dental polymer and more particularly forming a filler in powder form. The surface of the powder particles is preferably silanized. In one advantageous embodiment, the additional ingredients may be miscible with the dental composition in addition to the glass powder, examples of which include barium and/or strontium and/or lithium aluminate glass-ceramic powder, to further increase radiopacity. Additives for (e.g. yttrium trifluoride and/or yttrium fluoride), or fillers to adjust the viscosity (more specifically fumed silica and/or wet-settled silica).

Dental glass is preferably a filler into a composite material for treatment, more particularly for filling of dental voids and/or for dental restoration, more preferably for acrylate-based polymers requiring primarily chemically inert fillers (also (Referred to as filling composites). Likewise, the use of the glass according to the invention as a radiopaque agent in dental compositions, in particular polymer-based dental compositions, is within the context of the invention. The glass according to the invention is, for example, a suitable replacement for _{expensive crystalline radiopaque agents such as YbF 3.} The glass according to the invention is also suitable for use as a filler in dental cements, for example glass ionomer cements. Likewise, it is possible for the glass according to the invention to be used as an inert additive in glass ionomer cements. It is particularly preferred to be used as an inert additive in polymer-reinforced glass ionomer cements. Polymer-reinforced glass ionomer cements comprise one class of materials available over the past few years, which represents the cement hardening reaction itself, which can take a very long time, but also resins such as the composites described above to initially harden. Also includes the matrix.

Thus, the radiopaque glass according to the present invention is preferably used to prepare a dental glass/polymer composite comprising a dental polymer. The dental polymer is preferably acrylate, methacrylate, 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane (bis-GMA), triethylene glycol UV-curable resins based on dimethacrylate (TEGDMA or TEGMA, as meant herein), urethane dimethacrylate (UDMA), alkanediol dimethacrylate or cyanoacrylate.

Likewise, the use of the glass according to the invention as an optical component comprising the glass according to the invention is encompassed by the invention. It is understood that an optical component is any article, in particular a component, that can be used for optical applications. This may be a component through which light passes. Examples of such components include cover glass and/or lens components, as well as supports of other components, such as mirrors and glass fibers.

The cover glass is preferably used to protect electronic components. Of course, it likewise includes optoelectronic components. The cover glass is conventionally present in the form of a glass plate with a parallel planar surface, preferably installed on an electronic component, thereby being protected from environmental influences, but for example electromagnetic radiation, such as light and X-radiation, is a cover glass. Can pass through and interact with electronic components. However, for certain optoelectronic components, X-radiation can also be harmful. The cover glass made of the radiopaque glass according to the invention can thus be used, for example, for cases such as X-ray protective glass in medical devices.

A further possible application is the use of the radiopaque glass according to the invention as cover glass and/or substrate glass in display technology for cathode ray tubes (CRT).

Based on these optical properties, the glass according to the invention can likewise be used for optical applications. Since it is usually chemically inert, it is suitable for applications as substrate glass and/or cover glass in photovoltaic cells, for example silicon-based solar cells, coverings of organic solar cells and/or support materials for thin film photovoltaic modules. . The X-ray absorption of the glass according to the invention has, among other things, certain advantages in the use of photovoltaic modules in aerospace applications, since these modules can be exposed to specific intensity X-radiation outside the Earth's atmosphere. . In addition, the property of high X-ray absorption makes it possible to use the glass as an X-ray protective glass very generally.

Due to its high temperature stability, the glass according to the invention is also particularly suitable as lamp glass for use in halogen lamps and/or fluorescent tubes and related structures. If the mechanism of light generation in the lamp causes X-radiation, a particular advantage of the glass according to the invention is that this radiation can be taken away from the surroundings. In addition, the glass according to the invention can be used in an X-ray tube.

The vaporization of the glass according to the present invention by physical methods and the deposition of vaporized glass on the part are additionally included in the present invention. This physical vapor deposition process, also referred to simply as the PVD process, is familiar to those skilled in the art and is described in the examples of DE 102 22 964 B4. In this process, the glass according to the invention acts as a target to be vaporized. The components vapor-coated with glass according to the invention can be advantageous from both the chemical resistance of the glass and its absorption of X-rays.

In addition, taking into account its high stability, the glass according to the invention is likewise suitable for safe temporary and/or permanent storage of radioactive waste, and also as a matrix material for the embedding of radioactive materials.

These glasses also show advantages in applications as container glass or packaging for pharmaceutical products. From the standpoint of high stability with respect to the surrounding medium, interactions with components can be almost excluded.

Example

The invention is illustrated below with examples illustrating the teachings of the invention, but is not intended to be limited thereto.

[Table 1] Examples (AB) in% by weight

Table 1 includes examples of radiopaque glass in a preferred composition range. All data on the composition are listed in weight percent. The glass contains _{an advantageous combination of radiopaque agents of Cs 2} O, BaO and SnO ₂ and an additionally defined amount of fluorine. The combinations mentioned and fluorine together form an advantageous radiopaque system, in which an index of refraction in the range of 1.480 to 1.561 and a relative aluminum equivalent thickness in the range from approximately 120% up to more than approximately 1400% can be established.

All values for the relative aluminum equivalent thickness (ALET, unit %) listed in Table 1 corresponding to X-ray absorption (XRO, unit %) were determined in a method based on DIN ISO 4049. The gray value in the image was measured using image processing software and used for determination of X-ray absorption. Table 1 additionally lists the refractive index (n _d ) and density of the examples.

The glasses described in the examples were prepared as follows:

The raw materials for the oxide are weighed and injected, and then thoroughly mixed. The glass batch is melted at about 1580° C. into a discrete melt aggregate, then purified and homogenized. At a casting temperature of about 1600° C., the glass can be cast and processed as a ribbon or to other desired dimensions. In a solid, continuous assembly, the temperature can be reduced to about 100K or more.

For further processing, the cooled glass ribbon could be milled by a method known from DE 41 00 604 C1 to form a glass powder having an average particle size of 10 μm or less. Glass properties were determined for glass bulks not milled into powder. This glass has good chemical resistance in relation to water.

The chemical resistance of the modified examples of the glass according to the present invention are additionally listed in Table 1. As an example for the two examples, the hydrolysis resistance class (HGB) according to DIN ISO 719 is given. However, the glasses according to the invention achieve good values for acid resistance according to DIN 12116 and alkali resistance to DIN ISO 695.

Table G1500 below shows glasses having a refractive index in the range of 1.50. Values are given in weight percent.

Table G1515 below shows a glass having a refractive index in the range of 1.515. The values are given in weight percent.

Table G1525 below shows a glass having a refractive index in the range of 1.525. The values are given in weight percent.

Table G1550 below shows a glass having a refractive index in the range of 1.550. The values are given in weight percent.

The glasses shown in Tables G 1500, G 1515, G 1525 and G 1550 were fused experimentally, and thus, completely or at least partially, are the material of the present invention. Thus, the corresponding embodiment is also an embodiment of the present invention.

[Table 2] Comparative Example (VB) in% by weight

[Table 3] Comparative Example (VB) in mol%

Tables 2 and 3 list the composition, refractive index, and relative aluminum equivalent thickness in percent (ie, X-ray absorption, XRO, units %) of the comparative examples for comparison. Glass is known dental glass and radiopaque glass and/or filler material for use in dental compositions, wherein the radiopacity is in each case a variety of radiopaque agent systems (individual radiopaque agents and/or different radiopaque agents). It is derived from the use of a combination of tasks).

1 shows in graphical form an advantageous correlation between the refractive index and the relative aluminum equivalent thickness for Examples AB1 to AB12:

Within the claimed refractive index range of 1.480 to 1.561, the refractive index is assigned to the relative aluminum equivalent thickness ALET (unit %) as can be described as a function of:

Relative ALET (%) = (15480 to 15900) * n _d- (23015 to 22695).

According to a first advantageous variant of the present invention _{, a radiopaque glass having a refractive index (n d} ) in the refractive index range of 1.480 to 1.561 is at least the minimum relative aluminum equivalent thickness (minimum relative ALET) defined by the following equation. It is advantageous to have an aluminum equivalent thickness ALET (%):

Minimum relative ALET (%) = C * n _d -D, where C = 11000 and D = 16160.

_{It is added that a radiopaque glass having a refractive index (n d} ) in the refractive index range of 1.480 to 1.561 has a relative aluminum equivalent thickness ALET (%) less than the maximum relative aluminum equivalent thickness (maximum relative ALET) defined by the following equation. Is advantageous as:

Maximum relative ALET (%) = A * n _d -B, where A = 11430 and B = 16230.

For radiopaque glass, thus advantageously, _{all refractive indices in the n d} range of 1.480 to 1.561 can be assigned to the interval of the relative ALET bounded by a maximum relative ALET and a minimum relative ALET. A preferred radiopaque glass having a defined refractive index (n _d ) has a relative ALET that is advantageous to the section of the relative ALET, which section can be calculated by the above equation.

According to the first variant advantageous, the assignment value (n _d ; Relative ALET) establishes two linear equations defining the favorable upper and lower limits of the relative ALET in the _{n d} range of 1.480 to 1.561 for the preferred variant of the glass. It is done by doing. 2 shows a graph of the linear equations for AB1 to AB15. The graph forms a so-called "enveloping line". In the region between the upper enveloping line (maximum) and the lower enveloping line (minimum), _{an advantageous range of relative ALETs allocated in the n d} range of 1.480 to 1.561 is found in the preferred variant of the glass. As can be seen, the embodiment lies between the "enveloping lines".

According to a second advantage of the invention, in the refractive index range between 1.480 and 1.561, _{the allocation between the refractive index of the glass (n d} ) and the relative aluminum thickness ALET (%) is made through the description of the following section:

By way of example, the meaning of this is as follows: a radiopaque glass having a given composition according to the invention and a refractive index in _{the n d range of 1.490 to <1.510 (e.g. n d} = 1.50) has a relative ALET of at least 260% (Corresponds to the minimum ALET). At the maximum value, the ALET of this glass can preferably be 1000% (corresponding to the maximum ALET). For radiopaque glasses falling within different n _d ranges, other values shown in each case for "minimum ALET" and "maximum ALET" are also valid. Thus, for a relative ALET, “minimum ALET” defines a lower limit and “maximum ALET” defines an upper limit, which is referred to as the _{defined n d range.}

According to an alternative advantageous variant, in the refractive index range of 1.480 to 1.561, _{the allocation between the refractive index of the glass (n d} ) and the relative aluminum thickness ALET (%) is made through the description of the following section:

By way of example, the meaning of this is as follows: a radiopaque glass having a given composition according to the invention and a refractive index in _{the n d range of 1.480 to <1.490 (e.g. n d} = 1.485) has a relative ALET of at least 120% (Corresponds to the minimum ALET). At the maximum, the ALET of this glass can preferably be 760% (corresponding to the maximum ALET). For radiopaque glasses falling within different n _d ranges, other values shown in each case for "minimum ALET" and "maximum ALET" are also valid. Thus, for a relative ALET, “minimum ALET” defines a lower limit and “maximum ALET” defines an upper limit, which is referred to as the _{defined n d range.}

For data collection, glass bulks were prepared from the glass compositions of the examples and the relevant parameters were identified: the relative aluminum equivalent thickness (in %) was determined by the technique described above. The refractive index (n _d ) was determined in a known manner. The number of samples for each example was two. Each parameter was measured multiple times, and the average value was calculated for the refractive index and X-ray absorption. The correlation between the refractive index and radiopacity is, for example, in the radiopaque glass according to the present invention, such as a glass having an advantageous radiopaque agent system of _{SnO 2} , BaO, Cs _{2 O and F as shown in FIG. 1.} Can be expressed by linear regression.

For comparison, the refractive index and relative aluminum equivalent thickness are plotted in FIG. 1 for the comparative example mentioned as well, which is based on a different radiopaque agent system. It can be seen that the examples within the claimed refractive index range have higher X-ray absorption than the comparative examples (based on the individual refractive indices). For the same refractive index, the X-ray absorption value achieved in the preferred glass is _{substantially higher, for example at n d} = 1.548, Example AB1 has a relative ALET of 1240%, while Comparative Example VB1 has only 763 %, Comparative Example VB10 has only 276%, Comparative Example VB14 has only 190%. Likewise, in the low refractive index range of approximately 1.49, Example AB3 exhibits a relative ALET of 310%, while that of Comparative Example VB19 is only 80%. Thus, the X-ray visibility of the preferred glass in the context of the present invention, and the polymer-based dental composition made using the same, increases significantly. Thus, for the same thickness, optical components comprising preferred glass (e.g., glass protective components, etc.) will be made thinner by absorbing more X-radiation than known optical components for the same X-ray absorption. Because of this, weight reduction can be achieved.

Particularly in the case of a glass with a low refractive index, it has been difficult to increase the radiopacity until now, and it has been possible only to increase it insufficiently, because increasing the proportion of the radiopaque agent simultaneously increases the refractive index. to be. With _{an advantageous radiopaque system comprising SnO 2} , BaO, Cs ₂ O and F, a significant increase in radiopacity is achieved even at a low refractive index, and at a high refractive index, the aluminum equivalent thickness is very significant compared to the known glass. Is improved.

In Figure 2, _{Example AB15 related to radiopaque components Cs 2} O, BaO and SnO ₂ exhibits similar composition to Example AB7 and similarly high relative ALET, however, the refractive index of 1.504 is Example AB7 (n _d =1.525 Has a lower refractive index than ). This can contribute to the beneficial influence of the fluorine component, which allows the refractive index-in this particular case, to be specially adjusted to be lower. As a result, it is possible to manufacture glasses with a particularly high relative ALET and a relatively low refractive index.

The comparison of Examples AB13 and AB14, which can be seen in FIG. 2, has approximately the same refractive index, but different relative indices, through the proper selection of the _{radiopaque agent in the preferred radiopaque agent system comprising SnO 2} , BaO, Cs _{2 O and F.} It is clarified that it is possible to manufacture glass with ALET.

The advantageous equations, graphs and intervals described above to correlate the refractive index of the glass with the relative aluminum equivalent thickness are thus valid for the embodiments of the invention mentioned in Tables G 1500, G 1515, G 1525 and G 1550. (See Figs. 3 to 6). In this figure, advantageous upper and lower limits ("enveloping lines") appear as in the comparative examples for comparison.

The invention can also be further described by the following description:

1. A dental composition or dental material comprising a radiopaque glass according to the invention as a filler for treatment, more particularly for filling voids of human and/or animal teeth and/or for dental restoration.

2. Glass powder comprising powder particles composed of radiopaque glass according to the present invention.

3. The glass powder according to the description 2, wherein the surface of the existing powder particles is silanized.

4. Fillings for polymer-based dental compositions comprising the glass according to the invention for treatment, more particularly for filling voids of human and/or animal teeth and/or for tooth restoration.

5. A polymer-based dental composition comprising a radiopaque glass according to the invention or a glass powder composed of a glass according to the invention.

6. A dental glass/polymer composite comprising a radiopaque glass according to the present invention or a glass powder composed of a radiopaque glass according to the present invention.

7. In the description 6, the dental polymer is preferably acrylate, methacrylate, 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane (bis- GMA), triethylene glycol dimethacrylate (TEGDMA or TEGMA, as defined herein), urethane dimethacrylate (UDMA), alkanediol dimethacrylate or a UV-curable resin based on cyanoacrylate. Dental glass/polymer composite.

8. Dental glass/polymer glass ionomer cement comprising a radiopaque glass according to the invention or a glass powder composed of the glass according to the invention.

9. Dental glass for the preparation of dental glass/polymer dental compositions comprising dental polymers for treatment, more particularly for filling voids of human and/or animal teeth and/or for tooth restoration. The use of the radiopaque glass according to the invention as.

10. Use of radiopaque glass according to the invention as glass powder.

11. Use according to description 10, wherein the surface of the powder particles present is silanized.

12. Use according to description 10 or 11 in a dental glass/polymer dental composition comprising a dental polymer.

13.-as a radiopaque agent in a polymer-based dental composition, and/or

-As parts for optical applications, and/or

-As cover glass and/or substrate glass in display technology for cathode ray tubes (CRT), and/or

-As cover glass and/or substrate glass in photovoltaic cells, and/or

-As lamp glass in an X-ray tube, and/or

-As a material for the landfill of radioactive materials

Use of radiopaque glass according to the invention.

14. Contains the following components (in wt% based on oxide) and preferably 0-19 wt% La ₂ O _{3 having a refractive index (n d} ) of 1.480 to 1.561, which does not contain PbO except only impurities Radiopaque glass made:

15. Radiopaque glass comprising the following components (in weight percent based on oxide), having _{a refractive index (n d} ) of 1.480 to 1.510, which does not contain PbO except only impurities:

16. Radiopaque glass comprising the following components (in weight percent based on oxide), having _{a refractive index (n d} ) of 1.505 to 1.520, which does not contain PbO except only impurities:

17. Radiopaque glass comprising the following components (in weight percent based on oxide), having _{a refractive index (n d} ) of 1.519 to 1.542, which does not contain PbO except only impurities:

18. Radiopaque glass comprising the following components (in weight percent based on oxide), having _{a refractive index (n d} ) of 1.542 to 1.561, which does not contain PbO except only impurities:

19. Radiopaque glass comprising the following components (in weight percent based on oxide), having _{a refractive index (n d} ) of 1.480 to 1.561, which does not contain PbO and BaO except only impurities:

Using the described radiopaque _{agent combinations (SnO 2} , BaO, Cs ₂ O) and advantageously the defined addition of fluorine, it is possible to formulate a glass having a desired refractive index on the one hand and an extremely high X-ray absorption on the other hand. It is possible. In accordance with the present invention, in the refractive index range of 1.480 to 1.561, it is possible to implement a range of relative aluminum equivalent thicknesses of about 120% up to more than 1400%, for example up to 1600%.

_{This example also demonstrates that the refractive index (n d} ) of the glass system according to the invention, in particular in the range of 1.480 to 1.561, can be applied to the intended application without inhibition of the essential ALET. As a result, the system can be used not only as a filler, especially in dental compositions, but also in other applications that impose high requirements on factors including purity and/or chemical resistance and temperature stability. Glass systems can be manufactured at an advantageous cost on an industrial scale.

In addition, the glass according to the present invention is relatively easy to melt and is thus efficient to manufacture. If a glass system finds that the individual components change within the stated limits, for example, dental filling materials-adjusting the refractive index to the requirements of the application, such as those required for glass with improved ALET. It is possible. The possible refractive index variations included in the present invention are considerably wide. In particular, since only the defined selection of raw materials needs to be maintained within the material within the range of ratios that are varied in the amounts described above, such glass systems in particular enable rational industrial manufacture of glass within the present glass system. Thus, the procedural manner when melting glass within a glass system is also very similar.

Claims (21)

_{A radiopaque glass having a refractive index (n d} ) of 1.480 to 1.561, which does not contain PbO other than only impurities, and contains the following components (in weight percent based on oxide):

The radiopaque glass according to claim 1, which does not contain PbO except only impurities, and has a refractive index (n _d ) of 1.480 to 1.561, comprising the following components (in weight percent based on oxide) Glass:

The radiopaque glass according to claim 1, which does not contain PbO except only impurities, and has a refractive index (n _d ) of 1.480 to 1.561, comprising the following components (in weight percent based on oxide) Glass:

. The radiopaque glass according to claim 1 comprising the following components (in weight percent based on oxide):

. The radiopaque glass according to claim 2, comprising the following components (in weight percent based on oxide):

. The method according to any one of claims 1 to 5, wherein F in a proportion of up to 5.5% by weight and/or La ₂ O _{3 in} a content of 0-19% by weight and/or B in a content of 5-15% by weight Radiopaque glass containing ₂ O _3. The radiopaque glass according to any one of claims 1 to 5, wherein the sum of the proportions of _{BaO and Cs 2} O and SnO _{2 and F (in weight percent based on oxide) is ≧12%.} The radiopaque glass according to any one of claims 1 to 5, wherein _{the molar ratio of SnO 2 to} F is 0.4 or more and/or 0.85 or less. The radiopaque glass according to any one of claims 1 to 5, wherein _{the molar ratio of Cs 2} O to the sum of _{Cs 2} O + BaO + SnO ₂ is 0.05 or more and/or 0.48 or less. The radiopaque glass according to any one of claims 1 to 5, further comprising at least one of the following components (in weight percent based on oxide):

The method according to any one of claims 1 to 5, wherein, except for only impurities, the glass is Na ₂ O and/or Li ₂ O and/or MgO and/or CeO ₂ and/or TiO ₂ and/or La ₂ O ₃ and /Or radiopaque glass that does not contain _{ZrO 2.} The glass according to any one of claims 1 to 5, wherein the _{glass having a refractive index (n d} ) in the refractive index range of 1.480 to 1.561 is greater than the minimum relative aluminum equivalent thickness (minimum relative ALET) determined by the following equation: Or radiopaque glass with the same relative aluminum equivalent thickness ALET (%):
Minimum relative ALET (%) = C * n _d -D, where C = 11000 and D = 16160. _{The relative aluminum equivalent thickness ALET of claim 12, wherein the glass having a refractive index (n d} ) in the refractive index range of 1.480 to 1.561 is less than or equal to the maximum relative aluminum equivalent thickness (maximum relative ALET) determined by the following equation. Radiopaque glass with (%):
Maximum relative ALET (%) = A * n _d -B, where A = 11430 and B = 16230. The radiation according to any one of claims 1 to 5, wherein in the refractive index range of 1.480 to 1.561, _{the allocation value between the refractive index of glass (n d} ) and the relative aluminum equivalent thickness ALET (%) is as shown in the table below. Impermeable glass:

. The radiation according to any one of claims 1 to 5, wherein in the refractive index range of 1.480 to 1.561, _{the allocation value between the refractive index of glass (n d} ) and the relative aluminum equivalent thickness ALET (%) is as shown in the table below. Impermeable glass:

. Radiopaque glass consisting of the glass according to any one of claims 1 to 5 in the range of 95% (% by weight based on oxide) or more. Radiopaque glass according to any one of the preceding claims, for use in the medical field, in particular in the field of dental medicine, as dental glass and/or for diagnostic purposes. Radiopaque glass according to any one of the preceding claims, for use as dental glass for treatment, in particular for filling voids in human and/or animal teeth and/or for tooth restoration. . 18. The radiopaque glass of claim 17, wherein the dental glass is in the form of powder particles and is part of a polymer-based dental composition comprising a dental polymer. 19. The radiopaque glass of claim 18, wherein the dental glass is in the form of powder particles and is part of a polymer-based dental composition comprising a dental polymer. The method according to any one of claims 1 to 5,
-As a radiopaque agent in a polymer-based dental composition, and/or
-As parts for optical applications, and/or
-As cover glass and/or substrate glass in display technology in the case of a cathode ray tube (CRT), and/or
-As cover glass and/or substrate glass in photovoltaic cells, and/or
-As glass in an X-ray tube, and/or
-As a material for embedding radioactive materials
Radiopaque glass for use.

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