Amorphous phase lithium silicate glass product, and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of dental restoration materials. Provided are an amorphous phase lithium silicate glass product, and a preparation method therefor and the use thereof. The preparation method for the amorphous phase lithium silicate glass product provided in the present invention comprises the following steps: subjecting glass frit to heat treatment, so as to obtain an amorphous phase lithium silicate glass product, wherein the preparation raw materials of the glass frit comprises: SiO2, Li2O, Al2O3, P2O5 and an auxiliary agent, and the temperature of the heat treatment is 350-560ºC. The amorphous phase lithium silicate glass product prepared in the present invention is free of adhesion in terms of microstructure and macroscopically free of collapse, and has good edge stability and machinability; moreover, the amorphous phase lithium silicate glass product prepared in the present invention has relatively high linear transmittance.

Description

Amorphous lithium silicate glass product and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on June 14, 2023, with application number CN202310698706.9 and invention name “A kind of amorphous lithium silicate glass product and its preparation method and application”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of tooth restoration materials, and in particular to an amorphous lithium silicate glass product and a preparation method and application thereof. Background Art

[0003] The glass frit obtained by melting glass-ceramic raw materials is in a vitreous state. During the cutting and polishing process to prepare the restoration, the pure glass material is prone to chipping, resulting in poor marginal stability of the restoration and a poor fit of the margins after the patient wears the tooth. The main hazards caused by poor margin fit include: plaque accumulation, which can cause or aggravate periodontal inflammation; and excessive bonding gaps, which can lead to excessive adhesive thickness. Long-term chewing pressure can cause the adhesive to break and dissolve, leading to secondary caries at the restoration margin.

[0004] Currently, lithium disilicate glass-ceramics, obtained by high-temperature crystallization (generally >700°C), are commonly used in dental restorations. For example, CN113501668A and CN106413626A both utilize materials containing lithium disilicate crystals. However, due to the microscopic interlocking rod-like structure of lithium disilicate, direct cutting can easily damage the cutting needle and cause significant chipping at the edges of the restoration, hindering its final seating.

[0005] In order to solve the problem of material processing, material manufacturers have found an intermediate state in the process of forming lithium disilicate materials - lithium metasilicate state. This intermediate state is easier to cut than lithium disilicate state. Therefore, the mainstream products on the current market are generally lithium metasilicate products that are easy to cut. These products are all subjected to one or more heat treatments (heat treatment temperature is above 600 ° C) to precipitate lithium metasilicate ceramic phase (ceramic phase accounts for generally ≥50%) inside the glass before cutting and grinding. This can ensure the grinding and cutting effect to a certain extent. EP2284133B1 uses lithium silicate products with lithium metasilicate as the main crystal phase to manufacture dental restorations. The proportion of ceramic phase components inside it is too high, resulting in greater wear on the turning needle, and the lamellar or spherical lithium metasilicate grain morphology will inevitably cause macrostructural collapse due to adhesion of the microstructure during cutting or grinding, and the edge stability is poor.

[0006] Moreover, during the processing / preparation process, defects in the restorations of traditional lithium disilicate glass-ceramic materials and lithium metasilicate products cannot be observed due to their low light transmittance. However, when patients wear teeth and perform daily activities such as chewing, the defects on the restorations will quickly be exposed, which generally manifests clinically as fractures of the restorations.

[0007] Summary of the Invention

[0008] The object of the present invention is to provide an amorphous lithium silicate glass product, a preparation method and application thereof. The amorphous lithium silicate glass product prepared by the present invention does not have adhesion in the microstructure, does not show macroscopic chipping, has good edge stability and excellent machinability; at the same time, the amorphous lithium silicate glass product prepared by the present invention has high linear transmittance.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0010] The present invention provides a method for preparing an amorphous lithium silicate glass product, comprising the following steps:

[0011] heat-treating the glass material to obtain an amorphous lithium silicate glass product;

[0012] The raw materials for preparing the glass frit include: SiO2, Li2O, Al2O3, P2O5 and additives;

[0013] The temperature of the heat treatment is 350-560°C.

[0014] Preferably, the method for preparing the glass frit comprises: melting the raw materials for preparing the glass frit for the first time, pouring the obtained molten glass into water to obtain glass slag material; melting the glass slag material for the second time, pouring and molding the obtained glass liquid to obtain glass frit.

[0015] Preferably, the temperature of the first melting is 1250-1600° C.; and the time of the first melting is 1-8 hours.

[0016] Preferably, the temperature of the second melting is 1400-1600° C.; and the time of the second melting is 1-24 hours.

[0017] Preferably, the casting molding includes casting, cooling and solidification, and annealing in sequence;

[0018] The annealing temperature is 200-300° C., and the holding time is 1-20 hours.

[0019] Preferably, the heat treatment time is 2 minutes to 20 hours.

[0020] Preferably, the heat treatment is a single heat treatment or multiple heat treatments; the multiple heat treatments include: heating the glass material to a heat treatment temperature for a first heat treatment, then cooling it to room temperature with a furnace, and repeating the first heat treatment and furnace cooling; or subjecting the glass material to a gradient heat treatment.

[0021] The present invention provides an amorphous lithium silicate glass product prepared by the preparation method described in the above technical solution.

[0022] Preferably, the linear transmittance of the amorphous lithium silicate glass product is 75-95%.

[0023] The present invention provides the use of the amorphous lithium silicate glass product described in the above technical solution in the preparation of tooth restoration materials.

[0024] The present invention provides a method for preparing amorphous lithium silicate glass products. The present invention heat treats the glass material at 350-560°C, and a large number of small crystal nuclei are precipitated inside the obtained amorphous lithium silicate glass products. Due to the small size of the crystal nuclei, the product still appears to be glassy in a macroscopic manner, and the microscopic components cannot be detected by X-ray diffraction (XRD). These crystal nuclei are numerous and independent of each other, and there is no adhesion in the microstructure. Therefore, after cutting, there will be no macroscopic collapse, and the edge stability is better. In the present invention, since the small crystal nuclei material is easier to cut, when using the same turning needle for cutting, more material can be cut compared to the ceramic phase. The amorphous lithium silicate glass products prepared by the present invention save more turning needles and have excellent machinability. The results of the embodiment show that using the same set of turning needles, only 30-50 pieces can be cut when cutting a lithium silicate product with lithium metasilicate as the main crystal phase, while ≥80 pieces can be cut when cutting the amorphous lithium silicate glass products prepared by the present invention.

[0025] At the same time, the amorphous lithium silicate glass products prepared by the present invention have a high linear transmittance, preferably 75-95%. The present invention uses amorphous lithium silicate glass products with high linear transmittance to make dental restoration materials. During the processing / preparation process, the transparent state makes it easier to detect defects caused by the restoration during the processing. On the one hand, it can reduce the rework rate of the restoration, and on the other hand, it can also reduce the risk of the restoration breaking after the patient wears the tooth.

[0026] In addition, the heat treatment temperature of lithium metasilicate glass ceramic products is high, the treatment time is long, and the energy loss is large. The heat treatment temperature of the present invention is low, the treatment time is relatively short, and it saves more energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is an XRD pattern of the amorphous lithium silicate glass product prepared in Example 1;

[0028] FIG2 is an XRD pattern of the lithium silicate product prepared in Comparative Example 1;

[0029] FIG3 is a process flow chart of the gradient heat treatment of Example 7;

[0030] FIG4 is an XRD diagram of the amorphous lithium silicate glass products prepared in Examples 2 to 7. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing an amorphous lithium silicate glass product, comprising the following steps:

[0032] heat-treating the glass material to obtain an amorphous lithium silicate glass product;

[0033] The raw materials for preparing the glass frit include: SiO2, Li2O, Al2O3, P2O5 and additives;

[0034] The temperature of the heat treatment is 350-560°C.

[0035] The present invention heat-treats glass frit to obtain an amorphous lithium silicate glass product. In the present invention, the glass frit preparation method preferably comprises: melting the raw materials for preparing the glass frit for a first time, pouring the resulting molten glass into water to obtain a glass slag material; and melting the glass slag material for a second time, and casting the resulting glass liquid into a mold to obtain the glass frit.

[0036] In the present invention, the raw materials for preparing the glass frit are preferably mixed in the same container; the mixing is preferably performed manually or mechanically. In the present invention, the temperature of the first melting is preferably 1250-1600°C, more preferably 1400-1550°C, and even more preferably 1450-1500°C. The duration of the first melting is preferably 1-8 hours, more preferably 2-5 hours, and even more preferably 3-4 hours. In the present invention, the first melting is preferably performed in air. In the present invention, the molten glass obtained after the first melting is poured into water and directly quenched into glass slag. In the present invention, the temperature of the second melting is preferably 1400-1600°C, more preferably 1450-1580°C, and even more preferably 1500-1550°C. The duration of the second melting is preferably 1-24 hours, more preferably 8-24 hours, and even more preferably 10-20 hours. In the present invention, the second melting is preferably performed in air. The present invention utilizes the second melting to achieve a more uniform distribution of the glass frit composition.

[0037] In the present invention, the casting molding preferably includes casting, cooling and solidification, and annealing in sequence. In the present invention, the casting is preferably carried out in a mold; the present invention has no special requirements for the shape of the mold, which can be determined according to the needs of the product. In the present invention, the cooling and solidification is preferably carried out at room temperature. In the present invention, the annealing temperature is preferably 200-300°C, more preferably 240-280°C, and further preferably 250-260°C; the holding time is preferably 1-20h, more preferably 2-15h, and further preferably 8-12h. In the present invention, the annealing is preferably carried out in air.

[0038] In the present invention, the raw materials for preparing the glass frit preferably include: SiO2 55-75wt%, Li2O 10-25wt%, Al2O3 0.5-12wt%, P2O5 2-8wt%, additives 0.1-11wt%, and colorants 0-10wt%.

[0039] In the present invention, the raw materials for preparing the glass frit preferably include 55 to 75 wt % of SiO 2 , more preferably 58 to 73 wt %, and even more preferably 59 to 65 wt %.

[0040] In the present invention, the raw materials for preparing the glass frit preferably include 10-25 wt % of Li2O, more preferably 13-22 wt %, and even more preferably 15-20 wt %.

[0041] In the present invention, the raw materials for preparing the glass frit preferably include 0.5 to 12 wt % of Al 2 O 3 , more preferably 1 to 8 wt %, and even more preferably 2 to 6 wt %.

[0042] In the present invention, the raw materials for preparing the glass frit preferably include 2-8 wt % of P2O5, more preferably 4-6 wt %, and further preferably 5 wt %.

[0043] In the present invention, the raw materials for preparing the glass frit preferably include 0.1 to 11 wt % of additives, more preferably 2.3 to 10.8 wt % of additives, and even more preferably 6.1 to 8.3 wt %. In the present invention, the additives preferably include one or more of alkali metal oxides, divalent metal oxides, trivalent metal oxides, and tetravalent metal oxides. In the present invention, the alkali metal oxides preferably include one or more of Na2O and K2O; the divalent metal oxides preferably include one or more of BeO, MgO, CaO, SrO, BaO, and ZnO; the trivalent metal oxides preferably include one or more of B2O3, La2O3, and Bi2O3; and the tetravalent metal oxides preferably include one or more of ZrO2 and TiO2. In the present invention, the role of the additives is to adjust the amount and ratio of each component to adjust the viscosity of the glass system, the crystal precipitation time, and the crystal growth direction during the crystallization process.

[0044] In the present invention, the auxiliary agent more preferably includes one or more of Na2O, K2O, MgO, BaO, ZnO, B2O3, ZrO2 and TiO2. In a specific embodiment of the present invention, the mass ratio of Na2O, K2O, MgO, BaO, ZnO, B2O3, ZrO2 and TiO2 is preferably 0-1:0-0.2:0-1:0-0.3:0-3:0-2:1-8:0-1, more preferably 0.1-0.5:0.2:0.1-0.5:0.2-0.3:1-2.4:0.1-2:2-5:0.1-0.5.

[0045] In the present invention, the raw materials for preparing the glass frit preferably also include 0-10 wt % of a colorant, more preferably 2.7-6.9 wt % of a colorant, and even more preferably 3.1-4.7 wt % of a colorant. In the present invention, the colorant preferably includes one or more of a manganese-containing compound, a cobalt-containing compound, a nickel-containing compound, a copper-containing compound, a chromium-containing compound, a vanadium-containing compound, an iron-containing compound, and a rare earth element oxide. In the present invention, the manganese-containing compound is preferably MnO2; the cobalt-containing compound is preferably CoO; the nickel-containing compound is preferably Ni2O3; the copper-containing compound is preferably CuO; the chromium-containing compound is preferably Cr2O3; the vanadium-containing compound is preferably V2O5; the iron-containing compound is preferably Fe2O3; and the rare earth element oxide preferably includes one or more of Er2O3, CeO2, and Nd2O3.

[0046] In the present invention, the colorant more preferably includes one or more of CoO, Fe2O3, Er2O3, CeO2, and Nd2O3. In a specific embodiment of the present invention, the mass ratio of CoO, Fe2O3, Er2O3, CeO2, and Nd2O3 is preferably 0-0.1:0-0.2:0-2:2-4:0-0.8, more preferably 0-0.1:0.1-0.2:0.1-0.5:2.5-3.5:0.1-0.5, and further preferably 0.1:0.1-0.2:0.2-0.3:3.0-3.5:0.2-0.4.

[0047] After obtaining the glass frit, the present invention heat-treats the glass frit to obtain an amorphous lithium silicate glass product. In the present invention, the heat treatment temperature is 350-560°C, preferably 400-555°C, and more preferably 420-500°C. In the present invention, the heat treatment time is preferably 2 minutes to 20 hours, more preferably 20 minutes to 15 hours, and even more preferably 3-5 hours. In the present invention, the heating rate from room temperature to the heat treatment temperature is preferably 5-200°C / h, more preferably 20-50°C / h.

[0048] In the present invention, the heat treatment is preferably a single heat treatment or multiple heat treatments. In the present invention, the number of heat treatments in the multiple heat treatments is preferably 1 to 5 times, more preferably 1 to 3 times.

[0049] In the present invention, the multiple heat treatments preferably include: heating the glass material to a heat treatment temperature for a first heat treatment, then cooling it to room temperature in a furnace, and repeating the first heat treatment and furnace cooling. In the present invention, during the multiple heat treatments, the temperature of each heat treatment is independently 350 to 560°C, preferably 400 to 555°C, and more preferably 420 to 500°C. In the present invention, the time of each heat treatment is independently preferably 2 minutes to 20 hours, more preferably 20 minutes to 15 hours, and further preferably 3 to 5 hours.

[0050] In the present invention, the multiple heat treatments preferably include: subjecting the glass material to a gradient heat treatment. In the present invention, the gradient heat treatment preferably includes: first heating to an intermediate temperature at a first heating rate for a first heat preservation, and then heating to a final temperature at a second heating rate for a second heat preservation. In the present invention, the first heating rate is preferably 50 to 200°C / h, more preferably 100 to 150°C / h; the intermediate temperature is preferably 350 to 450°C, more preferably 380 to 420°C; the first heat preservation time is preferably 3 to 20h, more preferably 5 to 15h; the second heating rate is preferably 5 to 30°C / h, more preferably 10 to 20°C / h; the final temperature is preferably 450 to 560°C, more preferably 500 to 555°C; the second heat preservation time is preferably 20min to 20h, more preferably 1 to 10h. In a specific embodiment of the present invention, the gradient heat treatment includes: heating to 420°C at a heating rate of 50°C / h, keeping warm for 3 hours, then heating to 555°C at a heating rate of 30°C / h, and keeping warm for 20 minutes.

[0051] The product obtained by the heat treatment parameters described above is in a glassy or glass-like state and is an amorphous lithium silicate glass product. As a preferred embodiment, the present invention uses multiple heat treatments to further improve the machinability of the amorphous lithium silicate glass product.

[0052] In the present invention, the heat treatment is preferably carried out in air. In the present invention, after the heat treatment, the glass is preferably cooled to room temperature in the furnace to obtain an amorphous lithium silicate glass product.

[0053] The present invention provides an amorphous lithium silicate glass product prepared by the preparation method described in the above technical solution. In the present invention, the linear transmittance of the amorphous lithium silicate glass product is preferably 75-95%, more preferably 80-90%.

[0054] The present invention provides the use of the amorphous lithium silicate glass product described in the above technical solution in the preparation of a dental restorative material, preferably in the preparation of a dental restoration. In the present invention, the dental restoration preferably includes one or more of a veneer, an inlay, a crown, and a bridge. The present invention does not particularly require the specific method of application; methods familiar to those skilled in the art can be employed.

[0055] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0056] Example

[0057] The raw materials for preparing the glass frit are placed in the same container and mixed; the fully mixed raw materials are melted for the first time, and the obtained molten glass is directly poured into water and quenched into glass slag material;

[0058] The glass slag material is melted for a second time, the obtained glass liquid is poured into a mold, and then cooled, solidified and annealed in sequence to obtain glass material;

[0059] The glass material is heat-treated and then cooled to room temperature in the furnace to obtain an amorphous lithium silicate glass product.

[0060] The raw materials and process parameters for preparing the glass frit used in the examples are shown in Table 1.

[0061] Table 1 Raw material composition and process parameters of the embodiment

[0062] Example 7

[0063] The preparation method is basically the same as that in Example 1, except that the heat treatment is a gradient heat treatment. The specific process is shown in Figure 3: the temperature is raised to 420°C at a heating rate of 50°C / h, kept warm for 3 hours, then raised to 555°C at a heating rate of 30°C / h, kept warm for 20 minutes; then cooled to room temperature with the furnace to obtain an amorphous lithium silicate glass product.

[0064] Comparative Example 1

[0065] The preparation method is basically the same as that of Example 1, except that the heat treatment temperature is adjusted to 650° C., and the obtained sample is a lithium silicate product with lithium metasilicate as the main crystal phase.

[0066] Comparative Example 2

[0067] The preparation method is basically the same as that of Example 1, except that the heat treatment temperature is adjusted to 300° C. to obtain glass frit.

[0068] Test Example 1

[0069] Figure 1 shows the XRD pattern of the amorphous lithium silicate glass product prepared in Example 1. As can be seen from Figure 1, the XRD pattern of the sample prepared in Example 1 exhibits a "steamed bun peak," indicating a typical amorphous state. The XRD patterns of the amorphous lithium silicate glass products prepared in Examples 2-7 are shown in Figure 4, which is similar to that in Figure 1 and represents typical amorphous state samples.

[0070] FIG2 is an XRD diagram of the lithium silicate product prepared in Comparative Example 1. As can be seen from FIG2 , since Comparative Example 1 adopts a higher heat treatment temperature, the obtained sample is a lithium silicate product with lithium metasilicate as the main crystal phase.

[0071] The product prepared in Comparative Example 2 was glass material, and the tooth restoration broke during the cutting process and could not be completely cut out.

[0072] Test Example 2

[0073] Eight sets of identical new turning needles were prepared and used to cut the samples obtained in Examples 1 to 7 and Comparative Example 1. The amorphous lithium silicate glass product prepared in Example 1 could produce 80 dental restorations, the amorphous lithium silicate glass product prepared in Example 2 could produce 88 dental restorations, the amorphous lithium silicate glass product prepared in Example 3 could produce 83 dental restorations, the amorphous lithium silicate glass product prepared in Example 4 could produce 84 dental restorations, the amorphous lithium silicate glass product prepared in Example 5 could produce 82 dental restorations, and the amorphous lithium silicate glass product prepared in Example 6 could produce 85 dental restorations. The amorphous lithium silicate glass product prepared in Example 7 could produce 100 dental restorations. The turning needles could no longer be used after cutting 32 dental restorations from the lithium silicate product prepared in Comparative Example 1. This indicates that the amorphous lithium silicate glass product prepared in the present invention is easier to cut and requires fewer turning needles.

[0074] Test Example 3

[0075] The samples obtained in Examples 1 to 7 and Comparative Examples 1 to 2 were cut into small pieces with a size of length × width × thickness = 25 mm × 25 mm × 1 mm, and the linear transmittance of each sample was tested using a haze meter. The results are shown in Table 2.

[0076] Table 2 Linear transmittance of samples obtained from Examples 1 to 7 and Comparative Examples 1 to 2

[0077] As can be seen from Table 2, the amorphous lithium silicate glass products prepared in the present invention have higher linear transmittance. During the processing / preparation of dental restoration materials, the transparent state makes it easier to detect defects in the restoration. On the one hand, it can reduce the rework rate of the restoration, and on the other hand, it can avoid the fracture of the restoration after the patient wears the tooth.

[0078] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an amorphous lithium silicate glass product, comprising the following steps: The glass material is heat-treated to obtain an amorphous lithium silicate glass product; The raw materials for preparing the glass frit include: SiO2, Li2O, Al2O3, P2O5 and additives; The temperature of the heat treatment is 350-560°C.

2. The preparation method according to claim 1, characterized in that: The glass frit preparation method comprises: melting raw materials for preparing the glass frit for the first time, pouring the obtained molten glass into water to obtain glass slag material; melting the glass slag material for the second time, pouring and molding the obtained glass liquid to obtain glass frit.

3. The preparation method according to claim 2, characterized in that: The temperature of the first melting is 1250-1600° C.; the time of the first melting is 1-8 hours.

4. The preparation method according to claim 2, characterized in that: The temperature of the second melting is 1400-1600° C.; the time of the second melting is 1-24 hours.

5. The preparation method according to claim 2, characterized in that: The casting molding includes casting, cooling and solidification and annealing in sequence; The annealing temperature is 200-300° C., and the insulation time is 1-20 hours.

6. The preparation method according to claim 1, characterized in that: The raw materials for preparing the glass material include: SiO2 55-75wt%, Li2O 10-25wt%, Al2O3 0.5-12wt%, P2O5 2-8wt%, auxiliary agent 0.1-11wt%; and colorant 0-10wt%.

7. The preparation method according to claim 6, characterized in that: The auxiliary agent includes one or more of alkali metal oxides, divalent metal oxides, trivalent metal oxides and tetravalent metal oxides.

8. The preparation method according to claim 6 or 7, characterized in that: The auxiliary agent includes one or more of Na2O, K2O, MgO, BaO, ZnO, B2O3, ZrO2 and TiO2.

9. The preparation method according to claim 1, characterized in that: The heat treatment time is 2 minutes to 20 hours.

10. The preparation method according to claim 1, characterized in that: The heat treatment is one-time heat treatment or multiple heat treatments; the multiple heat treatments include: heating the glass material to a heat treatment temperature for the first heat treatment, then cooling it to room temperature with the furnace, repeating the first heat treatment and cooling it with the furnace; or subjecting the glass material to a gradient heat treatment.

11. The preparation method according to claim 10, characterized in that: The gradient heat treatment comprises: firstly heating the temperature to an intermediate temperature at a first heating rate for a first heat preservation, and then heating the temperature to a final temperature at a second heating rate for a second heat preservation; The first heating rate is 50-200°C / h; the intermediate temperature is 350-450°C; the first insulation time is 3-20h; The second heating rate is 5 to 30° C. / h; the final temperature is 450 to 560° C.; and the second insulation time is 20 min to 20 h.

12. Amorphous lithium silicate glass product prepared by the preparation method according to any one of claims 1 to 11.

13. The amorphous lithium silicate glass product according to claim 12, characterized in that: The linear transmittance of the amorphous lithium silicate glass product is 75-95%.

14. Use of the amorphous lithium silicate glass product according to any one of claims 12 to 13 in the preparation of tooth restoration materials.

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