A machinable lithium disilicate material and its preparation method and application

Abstract

The present invention provides a machinable lithium disilicate material, its preparation method, and application, relating to the field of glass-ceramic technology. The machinable lithium disilicate material provided by the present invention has a total crystal content greater than 75% and a light transmittance of 53% to 75%. The lithium disilicate material provided by the present invention not only combines the advantages of high crystal content, high transparency, high strength, and machinability, but can also be applied to areas of abutment teeth where the color and condition are excellent and no special color masking is required but where high strength is required. This is of great significance for improving the service life of dental restorative materials and the aesthetic restoration effect.

Description

Technical Field

[0001] The present invention relates to the technical field of glass ceramics, and in particular to a machinable lithium disilicate material and a preparation method and application thereof. Background Art

[0002] Lithium disilicate glass-ceramics possess excellent mechanical properties, translucency, and chemical stability, and hold promising prospects for development in dental restorations. Their unique, cross-linked, interlocking microstructure is crucial for their mechanical properties. However, while this microstructure ensures high strength, it also results in poor machinability. CAD / CAM processing can damage the machining tools, and the resulting restorations can suffer from severe chipping.

[0003] Therefore, common glass-ceramic dental restoration materials on the market are typically in an "intermediate state" with lithium metasilicate as the primary crystal phase. This material exhibits a lamellar or spherical microstructure, ensuring excellent workability. Using CAD / CAM technology, lithium metasilicate is processed into dental restorations, then subjected to high-temperature crystallization to achieve the "final state" with lithium disilicate as the primary crystal phase. After fine-tuning by the dentist, the restoration can be fitted. Slight shrinkage occurs from the "intermediate state" to the "final state," so material shrinkage must be considered during the layout design process when using CAD / CAM technology. However, with the accelerated pace of life, rapid tooth insertion is becoming increasingly popular among dentists and patients. Dental restorations in this "intermediate state" not only have to consider the challenges of tight fit due to material shrinkage, but also the increased time and equipment costs associated with high-temperature crystallization and cooling processes. This significantly prolongs treatment time and reduces effectiveness, resulting in a poor patient experience.

[0004] To address this issue, a dental restorative material that can be directly machined without high-temperature crystallization and can be placed directly on the tooth after simple polishing after CAD / CAM processing is urgently needed. This machinable dental restorative material eliminates the need for high-temperature crystallization, eliminating the need to consider the impact of shrinkage during crystallization on the fit of the tooth. It offers high machining precision and excellent treatment results. After machining, it can be placed on the tooth after simple polishing, eliminating the need for high-temperature crystallization and cooling, significantly reducing patient treatment time.

[0005] However, among the patents for machinable lithium silicate glass-ceramics, Chinese patent CN103648467A discloses a directly machinable lithium silicate glass-ceramic with lithium metasilicate as the sole or primary crystalline phase. By adding a relatively large amount of zirconium oxide, partial crystallization of the lithium metasilicate occurs in the first processing stage, and in the second stage, the proportion of the lithium metasilicate crystalline phase is increased to ensure that the sample meets strength requirements. Because the primary crystalline phase is lithium metasilicate, the glass-ceramic produced by this method has a low crystal content, low strength, and poor wear resistance. Chinese patent CN106413626A discloses a dental restoration with lithium disilicate as the primary crystalline phase, which can be directly machined and, after machining, does not require further heat treatment to obtain the desired dental restoration. This method involves adding a relatively high content of aluminum oxide to generate lithium aluminum silicate, which hinders crystal growth and reduces the content of the primary crystalline phase, lithium disilicate. However, excessively small grain size can lead to decreased mechanical properties and excessive transparency, shortening the lifespan of the restoration. The resulting lithium aluminum silicate impurities can also affect the color and brightness of the restoration, impacting the aesthetic effect. Chinese patent CN110139626A discloses a lithium disilicate blank prepared by a solid-phase sintering method. While this lithium disilicate blank can be directly machined, the surface of the original glass powder crystals is irregular, and even after cold isostatic pressing, pores still exist between the powders. This method of pressing the original glass powder before sintering results in a large number of pores in the blank, creating numerous defects that can easily cause cracks to propagate within the blank, impacting the mechanical properties of the restoration. Furthermore, the significant differences between the pores and the optical properties, such as the refractive index, of the lithium disilicate crystals result in uneven color and transparency, affecting the aesthetic quality of the restoration.

[0006] Therefore, it is necessary to develop a machinable lithium disilicate dental restoration material that combines the advantages of high crystal content, high transparency, high strength, and machinability to meet the requirements of the restoration for mechanical properties and aesthetic effects. Summary of the Invention

[0007] The present invention aims to provide a machinable lithium disilicate material, a preparation method thereof, and applications thereof. The lithium disilicate material provided by the present invention not only combines the advantages of high crystal content, high transparency, high strength, and machinability, but can also be applied to areas of abutment teeth where the color and condition are excellent and no special color masking is required but higher strength requirements are required. This is of great significance for improving the service life of dental restorative materials and the aesthetic restoration effect.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a machinable lithium disilicate material. The total crystal mass content of the machinable lithium disilicate material is greater than 75%, and the light transmittance is 53% to 75%.

[0010] Preferably, the machinable lithium disilicate material comprises a crystal structure in which ellipsoidal lithium disilicate grains are aggregated into clusters.

[0011] Preferably, the size of the ellipsoidal lithium disilicate grains is 50 nm to 500 nm.

[0012] Preferably, in terms of weight, the raw materials for preparing the machinable lithium disilicate material include: 58 to 82 parts of Si source; 8 to 27 parts of Li source; 1 to 5 parts of K source; 1.5 to 11.5 parts of Al source; 3 to 15 parts of P source; 0.1 to 9 parts of Ti source; and 0.6 to 8 parts of colorant. The weight of the Si source is calculated as SiO2; the weight of the Li source is calculated as Li2O; the weight of the K source is calculated as K2O; the weight of the Al source is calculated as Al2O3; the weight of the P source is calculated as P2O5; and the weight of the Ti source is calculated as TiO2.

[0013] Preferably, the colorant includes one or more of V2O5 and rare earth oxides.

[0014] The present invention provides a method for preparing the machinable lithium disilicate material described in the above technical solution, comprising the following steps:

[0015] The raw material powders are mixed, melted for the first time and then water quenched to obtain glass slag material;

[0016] The glass slag material is ball-milled and mixed, and then melted for a second time to obtain glass liquid;

[0017] shaping the glass liquid to obtain a glass body;

[0018] The glass body is sequentially annealed and heat-treated to obtain the machinable lithium disilicate material.

[0019] Preferably, the temperature of the first melting is 960° C. to 1680° C., and the holding time of the first melting is 120 min to 1080 min;

[0020] The temperature of the second melting is 1400° C. to 1680° C., and the time of the second melting is 30 min to 480 min.

[0021] Preferably, the annealing temperature is 300° C. to 550° C., and the annealing holding time is 1 hour to 18 hours.

[0022] Preferably, the temperature of the heat treatment is 550° C. to 950° C., and the holding time of the heat treatment is 6 min to 360 min.

[0023] The present invention provides the use of the machinable lithium disilicate material described in the above technical solution or the machinable lithium disilicate material prepared by the preparation method described in the above technical solution in the preparation of dental restoration materials.

[0024] The present invention provides a machinable lithium disilicate material. The machinable lithium disilicate material provided by the present invention can not only be directly machined but also has high strength.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The machinable lithium disilicate material of the present invention has lithium disilicate as the sole or main crystal phase, and can be directly processed by CAD / CAM machining. After grinding and polishing, it can be directly worn on the teeth without considering the problem of tooth tightness caused by material shrinkage and the increase in time and equipment costs caused by high-temperature crystallization and cooling processes.

[0027] (2) The machinable lithium disilicate material of the present invention has a high crystal content (total crystal content > 75%) and a high light transmittance (53% to 75%). The special microstructure of the ellipsoidal lithium disilicate grains aggregated into clusters ensures that the restoration material has a high strength (≥ 300 MPa) and can be directly machined.

[0028] (3) The machinable lithium disilicate material provided by the present invention not only combines the advantages of high crystal content, high transparency, high strength, and machinability, but can also be applied to areas of abutment teeth that have excellent color and condition and do not require special color masking but have high strength requirements. This is of great significance for improving the service life of dental restorative materials and the aesthetic restoration effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is an SEM image of the machinable lithium disilicate material prepared in Example 1;

[0030] Figure 2 This is the XRD pattern of the machinable lithium disilicate material prepared in Example 1;

[0031] Figure 3 The SEM and XRD patterns of the machinable lithium disilicate material prepared in Example 2;

[0032] Figure 4 The SEM and XRD patterns of the machinable lithium disilicate material prepared in Example 3;

[0033] Figure 5 The SEM and XRD patterns of the machinable lithium disilicate material prepared in Example 4;

[0034] Figure 6The SEM and XRD patterns of the machinable lithium disilicate material prepared in Example 5;

[0035] Figure 7 These are the SEM and XRD patterns of the machinable lithium disilicate material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0036] The present invention provides a machinable lithium disilicate material. The total crystal mass content of the machinable lithium disilicate material is greater than 75%, and the light transmittance is 53% to 75%.

[0037] In the present invention, the total crystal mass content of the machinable lithium disilicate material is greater than 75%, preferably 76-96%, and more preferably 76%, 80%, 85%, 90% or 96%.

[0038] In the present invention, the light transmittance of the machinable lithium disilicate material is 53% to 75%, and is preferably 53%, 58%, 63%, 70% or 74.5%.

[0039] In the present invention, the machinable lithium disilicate material preferably comprises a crystal structure composed of clusters of ellipsoidal lithium disilicate grains, more preferably primarily composed of clusters of ellipsoidal lithium disilicate grains, inevitably containing some independently existing ellipsoidal lithium disilicate grains. This unique microstructure ensures that the lithium disilicate material possesses high strength (≥300 MPa) while also being directly machinable.

[0040] In the present invention, the size of the ellipsoidal lithium disilicate grains is preferably 50 nm to 500 nm, and more preferably 50 nm, 75 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 225 nm, 250 nm, 275 nm, 300 nm, 325 nm, 350 nm, 375 nm, 400 nm, 425 nm, 450 nm, 475 nm, or 500 nm. In the present invention, the size of the ellipsoidal lithium disilicate grains refers to the length of the major axis of the ellipsoid.

[0041] In the present invention, the machinable lithium disilicate material preferably has lithium disilicate as the sole or main crystal phase.

[0042] In the present invention, the machinable lithium disilicate material has a relatively high three-point bending strength (≥300 MPa), such as 300 MPa, 330 MPa, 360 MPa, 390 MPa, 420 MPa, 450 MPa, 480 MPa or 510 MPa.

[0043] In the present invention, the raw materials for preparing the machinable lithium disilicate material preferably include, in parts by weight: 58 to 82 parts of Si source; 8 to 27 parts of Li source; 1 to 5 parts of K source; 1.5 to 11.5 parts of Al source; 3 to 15 parts of P source; 0.1 to 9 parts of Ti source; and 0.6 to 8 parts of colorant. The weight of the Si source is calculated as SiO2; the weight of the Li source is calculated as Li2O; the weight of the K source is calculated as K2O; the weight of the Al source is calculated as Al2O3; the weight of the P source is calculated as P2O5; and the weight of the Ti source is calculated as TiO2.

[0044] In the present invention, the raw materials for preparing the machinable lithium disilicate material preferably include 58 to 82 parts by weight of a Si source, and more preferably 58, 59, 61, 70, 79, 80, 81, or 82 parts by weight. In the present invention, the Si source is preferably SiO2; the parts by weight of the Si source are calculated as SiO2.

[0045] Based on the weight of the SiO2, the raw materials for preparing the machinable lithium disilicate material preferably include 8 to 27 parts of a Li source, and more preferably 8, 9, 10, 13, 18, 22, 25, 26, or 27 parts. In the present invention, the Li source is preferably Li2CO3 or Li2O; the weight of the Li source is calculated as Li2O.

[0046] Based on the weight of the SiO2, the raw materials for preparing the machinable lithium disilicate material preferably include 1 to 5 parts of a K source, and more preferably 1.0 part, 1.1 part, 1.2 parts, 1.8 parts, 2.6 parts, 4.2 parts, 4.8 parts, 4.9 parts, or 5.0 parts. In the present invention, the K source preferably includes K2CO3 or KH2PO4; the weight of the K source is calculated as K2O.

[0047] Based on the weight of the SiO2, the raw material for preparing the machinable lithium disilicate material preferably includes 1.5 to 11.5 parts of an Al source, and more preferably 1.5, 1.6, 1.7, 1.8, 3.5, 5.5, 9.5, 10.5, 11.0, or 11.5 parts. In the present invention, the Al source preferably includes Al2O3, Al(NO3)3, or Al(OH)3; the weight of the Al source is calculated as Al2O3.

[0048] Based on the weight of the SiO2, the raw materials for preparing the machinable lithium disilicate material preferably include 3 to 15 parts of a P source, and more preferably 3 parts, 4 parts, 5 parts, 6 parts, 9 parts, 12 parts, 13 parts, 14 parts, or 15 parts. In the present invention, the P source preferably includes (NH4)2HPO4 or KH2PO4; the weight of the P source is calculated as P2O5.

[0049] Based on the weight of the SiO2, the raw material for preparing the machinable lithium disilicate material preferably includes 0.1 to 9 parts of a Ti source, and more preferably 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 1.5, 3.5, 6.5, 8, 8.5, or 9.0 parts. In the present invention, the Ti source preferably includes TiO2; the weight of the Ti source is calculated as TiO2.

[0050] Based on the weight of the SiO2, the raw materials for preparing the machinable lithium disilicate material preferably include 0.6 to 8 parts of colorant, specifically preferably 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 3.5 parts, 5.5 parts, 7.5 parts, 7.6 parts, 7.7 parts, 7.8 parts, 7.9 parts or 8.0 parts.

[0051] In the present invention, the colorant preferably includes one or more of V2O5 and rare earth oxides; the rare earth oxides preferably include CeO2, Er2O3, Pr6O 11 and one or more of Nd2O3.

[0052] The present invention provides a method for preparing the machinable lithium disilicate material described in the above technical solution, comprising the following steps:

[0053] The raw material powders are mixed, melted for the first time and then water quenched to obtain glass slag material;

[0054] The glass slag material is ball-milled and mixed, and then melted for a second time to obtain glass liquid;

[0055] shaping the glass liquid to obtain a glass body;

[0056] The glass body is sequentially annealed and heat-treated to obtain the machinable lithium disilicate material.

[0057] In the present invention, raw material powders are mixed, melted for the first time, and then water-quenched to obtain glass slag material. In the present invention, the composition of the raw material powders is consistent with the raw materials for preparing the machinable lithium disilicate material described above, and will not be repeated here.

[0058] The present invention has no special requirements on the particle size of each raw material powder, and commercially available products well known in the art can be directly used.

[0059] In the present invention, the temperature of the first melting is preferably 960°C to 1680°C, and the holding time of the first melting is preferably 120min to 1080min. In the present invention, the temperature rise program of the first melting is preferably a single-stage temperature rise or a multi-stage temperature rise, more preferably a two-stage temperature rise. In the present invention, when the first melting is a two-stage temperature rise program, the first melting preferably includes: first heating the raw material mixed powder to the temperature of the first melting stage and performing a first holding, followed by a second heating to the temperature of the second melting stage and performing a second holding. In the present invention, the temperature of the first melting stage is preferably 960°C to 1100°C, specifically preferably 960°C, 970°C, 980°C, 1000°C, 1050°C or 1100°C; the first holding time is preferably 400min to 600min, specifically preferably 400min, 450min, 500min, 550min or 600min; the temperature of the second melting stage is preferably 1500°C to 1680°C, specifically preferably 1500°C, 1550°C, 1600°C, 1650°C or 1680°C; the second holding time is preferably 120min to 480min, specifically preferably 120min, 180min, 240min, 360min or 480min. In the present invention, the rates of the first and second heating are independently preferably 5°C / min to 20°C / min, more preferably 8°C / min to 15°C / min, and most preferably 10°C / min.

[0060] After obtaining the glass slag, the present invention ball-mills the glass slag and performs a second melting to obtain glass liquid. In the present invention, the ball-milling speed is preferably 100 to 900 r / min, and more preferably 100 r / min, 200 r / min, 300 r / min, 700 r / min, 800 r / min, or 900 r / min; the ball-milling time is preferably 5 to 180 minutes, and more preferably 5 minutes, 10 minutes, 20 minutes, 30 minutes, 60 minutes, 120 minutes, 150 minutes, or 180 minutes.

[0061] In the present invention, the temperature of the second melting is preferably 1400°C to 1680°C, and the holding time of the second melting is preferably 30 minutes to 840 minutes. In the present invention, the second melting is preferably a single-stage holding or a multi-stage holding, more preferably a two-stage holding. In the present invention, when the second melting is a two-stage holding, the second melting preferably comprises: heating the mixture obtained by ball milling to the temperature of the first melting stage for holding in the first stage, and cooling it to the temperature of the second melting stage for holding in the second stage. In the present invention, the melting temperature of the first stage is preferably 1560°C to 1680°C, specifically preferably 1560°C, 1580°C, 1600°C, 1650°C or 1680°C; the insulation time of the first stage is preferably 120min to 480min, specifically preferably 120min, 180min, 240min, 360min or 480min; the melting temperature of the second stage is preferably 1400°C to 1560°C, specifically preferably 1400°C, 1450°C, 1500°C or 1560°C; the insulation time of the second stage is preferably 30min to 360min, specifically preferably 30min, 60min, 120min, 180min, 240min or 360min.

[0062] In the present invention, the heating rate from room temperature to the melting temperature of stage I is preferably 5°C / min to 20°C / min, more preferably 8°C / min to 15°C / min, and most preferably 10°C / min. The cooling rate from the melting temperature of stage I to the melting temperature of stage II is preferably 5°C / min to 20°C / min, more preferably 8°C / min to 15°C / min, and most preferably 10°C / min.

[0063] After obtaining the molten glass, the present invention shapes the molten glass to obtain a glass body. In the present invention, the shaping is preferably performed in a mold, more preferably a graphite mold. In the present invention, the mold is preferably preheated before casting the molten glass. The preheating temperature is preferably 450°C to 750°C, and more preferably 450°C, 500°C, 550°C, 600°C, 650°C, or 750°C. The preheating time is preferably 30 minutes to 360 minutes, and more preferably 30 minutes, 60 minutes, 90 minutes, 150 minutes, 180 minutes, 240 minutes, or 360 minutes.

[0064] After obtaining the glass body, the present invention sequentially anneals and heat treats the glass body to obtain the machinable lithium disilicate material. In the present invention, the annealing temperature is preferably 300°C to 550°C, specifically preferably 300°C, 350°C, 450°C, 500°C or 550°C; the annealing holding time is preferably 1h to 18h, specifically preferably 1h, 2h, 3h, 6h, 12h or 18h. In the present invention, the annealing atmosphere is preferably an air atmosphere. In the present invention, the purpose of the annealing is to reduce or eliminate the uneven residual thermal stress and optical instability formed in the glass body during the hot forming process, thereby achieving a stable internal structure of the glass.

[0065] In the present invention, the temperature of the heat treatment is preferably 550°C to 950°C, and the holding time of the heat treatment is preferably 6 minutes to 360 minutes. In the present invention, the temperature of the heat treatment is preferably greater than the annealing temperature. In the present invention, the heating program of the heat treatment is preferably a single-stage heating program or a multi-stage heating program, more preferably a two-stage heating program. In the present invention, when the heat treatment is a two-stage heating program, the heat treatment preferably includes: heating the glass body from the annealing temperature to the temperature of the first stage heat treatment and holding the temperature, and then heating to the temperature of the second stage heat treatment and holding the temperature. In the present invention, the temperature of the first heat treatment is preferably 550°C to 650°C, specifically preferably 550°C, 580°C, 620°C or 650°C; the holding time of the first heat treatment is preferably 1h to 3h, specifically preferably 1h, 1.5h, 2h, 2.5h or 3h; the temperature of the second heat treatment is preferably 750°C to 950°C, specifically preferably 750°C, 780°C, 800°C, 850°C, 880°C, 890°C or 900°C; the holding time of the second heat treatment is preferably 6min to 180min, specifically preferably 6min, 15min, 20min, 30min, 60min, 120min, 150min or 180min. In the present invention, the atmosphere of the heat treatment is preferably an air atmosphere. In the present invention, the temperature of the first heat treatment is near the first crystallization peak temperature, so that the glass system begins to crystallize and forms a large number of lithium metasilicate crystal nuclei; the temperature of the second heat treatment is near the second crystallization peak temperature, so that the lithium metasilicate formed in the system is converted into lithium disilicate, and at the same time the crystal size grows larger and the mechanical properties are improved.

[0066] In the present invention, the heating rates from the annealing temperature to the first heat treatment temperature and from the first heat treatment temperature to the second heat treatment temperature are independently preferably 3°C / min to 10°C / min, more preferably 5°C / min.

[0067] In the present invention, after the heat treatment, the obtained material is preferably cooled to room temperature to obtain the machinable lithium disilicate material.

[0068] The present invention adopts the above-mentioned heat treatment process, which can make the lithium disilicate material have a high crystal content (total crystal content>75%) and a high light transmittance (53% to 75%).

[0069] The present invention provides the use of the machinable lithium disilicate material described in the above technical solution, or the machinable lithium disilicate material prepared by the preparation method described in the above technical solution, in the preparation of dental restoration materials. The present invention preferably directly processes the machinable lithium disilicate material into a dental restoration material. The dental restoration does not require further sintering and can be directly worn after only grinding and polishing.

[0070] 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.

[0071] Example 1

[0072] This embodiment provides a machinable lithium disilicate material. The preparation method of the machinable lithium disilicate material is as follows:

[0073] Analytically pure SiO2, Li2CO3, K2CO3, Al2O3, (NH4)2HPO4, TiO2, CeO2, and Er2O3 were weighed according to the mass percentages of the basic glass components. The mass percentages of the corresponding oxides for each component are shown in Table 1. After the raw material powders were uniformly mixed, they were placed in a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 960°C at a rate of 10°C / min and held for 500 minutes. The temperature was then raised to 1520°C at a rate of 10°C / min and held for 120 minutes. After removal, the crucible was poured into water for quenching to obtain glass slag.

[0074] The glass slag material was placed in a ball mill and ball-milled at 600 r / min for 10 minutes. The ground glass slag material was put back into a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 1580°C at a rate of 10°C / min and kept warm for 240 minutes. The temperature was then lowered to 1500°C at a rate of 10°C / min and kept warm for 60 minutes. After being taken out, the glass body was cast into a graphite mold preheated at 450°C for 180 minutes to obtain a glass blank.

[0075] The glass body was annealed at 450°C for 2 hours, then heated to 582°C at a heating rate of 5°C / min and kept warm for 60 minutes; then heated to 798°C at a heating rate of 5°C / min and kept warm for 10 minutes. After cooling to room temperature, a machinable lithium disilicate material was obtained.

[0076] The microstructure and XRD pattern of the machinable lithium disilicate material prepared in this embodiment are shown in FIG. Figure 1 and Figure 2 As shown. Figure 1 It can be seen that the lithium disilicate material is mainly composed of ellipsoidal lithium disilicate grains aggregated into cluster-like crystal structures. Figure 2 The XRD diffraction peak intensity and the integrated area of the crystalline peak calculated using Jade indicated a crystalline content of 79%. Furthermore, the material had a light transmittance of 74%. The SEM images revealed ellipsoidal lithium disilicate grains with a size of 160 nm. The three-point flexural strength of the material, measured according to the test method specified in GB / T30367-2013 7.3.2, was 303 MPa. The material was then prepared into C14-shaped ceramic blocks and used to cut dental restorations (veneers) using a CMW400 cutting machine until the cutting needle broke. The number of dental restorations that could be cut was calculated, and a set of cutting needles was found to be capable of cutting over 30 veneers.

[0077] Example 2

[0078] This embodiment provides a machinable lithium disilicate material. The preparation method of the machinable lithium disilicate material is as follows:

[0079] Analytically pure SiO2, Li2CO3, K2CO3, Al2O3, (NH4)2HPO4, TiO2, CeO2, and Er2O3 were weighed according to the mass percentages of the basic glass components. The mass percentages of the corresponding oxides of each component are shown in Table 1. After the raw material powders were uniformly mixed, they were placed in a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 960°C at a rate of 10°C / min and held at this temperature for 560 minutes. The temperature was then raised to 1600°C at a rate of 10°C / min and held at this temperature for 120 minutes. After removal, the crucible was poured into water for quenching to obtain glass slag.

[0080] The glass slag material was placed in a ball mill and ball-milled at 600 r / min for 10 minutes. The ground glass slag material was put back into a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 1620°C at a heating rate of 10°C / min and kept warm for 240 minutes. The temperature was then lowered to 1520°C at a cooling rate of 10°C / min and kept warm for 60 minutes. After being taken out, the glass slag material was cast into a graphite mold preheated at 450°C for 180 minutes to obtain a glass blank.

[0081] The glass body was annealed at 450° C. for 2 h, then heated to 582° C. at a heating rate of 5° C. / min and kept warm for 60 min; then heated to 850° C. at a heating rate of 5° C. / min and kept warm for 120 min. After cooling to room temperature, a machinable lithium disilicate material was obtained.

[0082] The SEM and XRD patterns of the machinable lithium disilicate material prepared in this embodiment are shown in FIG. Figure 3 As shown, its crystal content is 94%, the transmittance is 68%, the ellipsoidal lithium disilicate grain size is 240nm, the three-point bending strength is 398MPa, and a set of turning needles can cut more than 27 veneers.

[0083] Example 3

[0084] This embodiment provides a machinable lithium disilicate material. The preparation method of the machinable lithium disilicate material is as follows:

[0085] Analytically pure SiO2, Li2CO3, K2CO3, Al2O3, (NH4)2HPO4, TiO2, CeO2, and Er2O3 were weighed according to the mass percentages of the basic glass components. The mass percentages of the corresponding oxides of each component are shown in Table 1. After the raw material powders were uniformly mixed, they were placed in a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 960°C at a rate of 10°C / min and held for 500 minutes. The temperature was then raised to 1620°C at a rate of 10°C / min and held for 180 minutes. After removal, the crucible was poured into water for quenching to obtain glass slag.

[0086] The glass slag material was placed in a ball mill and ball-milled at 600 r / min for 10 minutes. The ground glass slag material was put back into a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 1580°C at a rate of 10°C / min and kept warm for 300 minutes. The temperature was then lowered to 1520°C at a rate of 10°C / min and kept warm for 60 minutes. After being taken out, the glass body was cast into a graphite mold preheated at 450°C for 120 minutes to obtain a glass blank.

[0087] The glass body was annealed at 450° C. for 3 hours, then heated to 582° C. at a heating rate of 5° C. / min and kept warm for 60 minutes; then heated to 850° C. at a heating rate of 5° C. / min and kept warm for 120 minutes. After cooling to room temperature, a machinable lithium disilicate material was obtained.

[0088] The SEM and XRD patterns of the machinable lithium disilicate material prepared in this embodiment are shown in FIG. Figure 4 As shown, its crystal content is 96%, the transmittance is 65%, the ellipsoidal lithium disilicate grain size is 280nm, the three-point bending strength is 440MPa, and a set of turning needles can cut more than 24 veneers.

[0089] Example 4

[0090] This embodiment provides a machinable lithium disilicate material. The preparation method of the machinable lithium disilicate material is as follows:

[0091] Analytically pure SiO2, Li2CO3, K2CO3, Al2O3, (NH4)2HPO4, TiO2, CeO2, and Er2O3 were weighed according to the mass percentages of the basic glass components. The mass percentages of the corresponding oxides of each component are shown in Table 1. After the raw material powders were uniformly mixed, they were placed in a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 960°C at a rate of 10°C / min and held for 500 minutes. The temperature was then raised to 1620°C at a rate of 10°C / min and held for 180 minutes. After removal, the crucible was poured into water for quenching to obtain glass slag.

[0092] The glass slag material was placed in a ball mill and ball-milled at 600 r / min for 10 minutes. The ground glass slag material was put back into a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 1580°C at a rate of 10°C / min and kept warm for 300 minutes. The temperature was then lowered to 1520°C at a rate of 10°C / min and kept warm for 120 minutes. After being taken out, the glass body was cast into a graphite mold preheated at 450°C for 120 minutes to obtain a glass blank.

[0093] The glass body was annealed at 450° C. for 3 hours, then heated to 582° C. at a heating rate of 5° C. / min and kept warm for 60 minutes; then heated to 810° C. at a heating rate of 5° C. / min and kept warm for 30 minutes. After cooling to room temperature, a machinable lithium disilicate material was obtained.

[0094] The SEM and XRD patterns of the machinable lithium disilicate material prepared in this embodiment are shown in FIG. Figure 5 As shown, its crystal content is 89%, the transmittance is 69%, the ellipsoidal lithium disilicate grain size is 290nm, the three-point bending strength is 468MPa, and a set of turning needles can cut more than 24 veneers.

[0095] Example 5

[0096] This embodiment provides a machinable lithium disilicate material. The preparation method of the machinable lithium disilicate material is as follows:

[0097] Analytically pure SiO2, Li2CO3, K2CO3, Al2O3, (NH4)2HPO4, TiO2, CeO2, and Er2O3 were weighed according to the mass percentages of the basic glass components. The mass percentages of the corresponding oxides of each component are shown in Table 1. After the raw material powders were uniformly mixed, they were placed in a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 960°C at a rate of 10°C / min and held for 500 minutes. The temperature was then raised to 1620°C at a rate of 10°C / min and held for 180 minutes. After removal, the crucible was poured into water for quenching to obtain glass slag.

[0098] The glass slag material was placed in a ball mill and ball-milled at 600 r / min for 10 minutes. The ground glass slag material was put back into a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 1580°C at a rate of 10°C / min and kept warm for 300 minutes. The temperature was then lowered to 1520°C at a rate of 10°C / min and kept warm for 120 minutes. After being taken out, the glass body was cast into a graphite mold preheated at 450°C for 120 minutes to obtain a glass blank.

[0099] The glass body was annealed at 450° C. for 3 hours, then heated to 582° C. at a heating rate of 5° C. / min and kept warm for 60 minutes; then heated to 810° C. at a heating rate of 5° C. / min and kept warm for 30 minutes. After cooling to room temperature, a machinable lithium disilicate material was obtained.

[0100] The SEM and XRD patterns of the machinable lithium disilicate material prepared in this embodiment are shown in FIG. Figure 6 As shown, its crystal content is 91%, the transmittance is 64%, the ellipsoidal lithium disilicate grain size is 295nm, the three-point bending strength is 480MPa, and a set of turning needles can cut more than 21 veneers.

[0101] Comparative Example 1

[0102] In this comparative example, analytically pure SiO2, Li2CO3, K2CO3, Al2O3, (NH4)2HPO4, TiO2, CeO2, and Er2O3 were weighed according to the mass percentages of the basic glass components. The mass percentages of the corresponding oxides of each component are shown in Table 1. After uniformly mixing the raw material powders, they were placed in a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 960°C at a rate of 10°C / min and held at this temperature for 500 minutes. The temperature was then raised to 1620°C at a rate of 10°C / min and held at this temperature for 180 minutes. The crucible was then removed and quenched in water to produce glass slag.

[0103] The glass slag material was placed in a ball mill and ball-milled at 600 r / min for 10 minutes. The ground glass slag material was put back into a platinum crucible and placed in a high-temperature resistance furnace. The temperature was raised to 1580°C at a rate of 10°C / min and kept warm for 300 minutes. The temperature was then lowered to 1520°C at a rate of 10°C / min and kept warm for 120 minutes. After being taken out, the glass body was cast into a graphite mold preheated at 450°C for 120 minutes to obtain a glass blank.

[0104] The glass blank was annealed at 450° C. for 3 h, then heated to 582° C. at a heating rate of 5° C. / min and kept warm for 60 min; then heated to 810° C. at a heating rate of 5° C. / min and kept warm for 30 min. After cooling to room temperature, a lithium disilicate dental restoration material was obtained.

[0105] The SEM and XRD patterns of the lithium disilicate dental restoration material described in this comparative example are shown in FIG. Figure 7 As shown, its crystal content is 94%, the transmittance is 53%, the short rod-shaped lithium disilicate grain size is 450nm, the three-point bending strength is 498MPa, and it is not machinable.

[0106] Table 1 Basic glass composition of Examples and Comparative Examples (percentage by weight)

[0107]

[0108]

[0109] In order to more intuitively compare the effect data of the embodiments and comparative examples, the test results of the crystal content, light transmittance, strength and cutting properties of the machinable lithium disilicate dental restorations prepared in the above embodiments and comparative examples are summarized, and the results are shown in Table 2.

[0110] Table 2 Crystal content, light transmittance, bending strength and machinability of the examples and comparative examples

[0111]

[0112] As can be seen from Examples 1 to 5 and Comparative Example 1, the machinable lithium disilicate material provided by the present invention has lithium disilicate as the sole or primary crystalline phase. Conventional lithium disilicate dental restoration materials have a cross-linked, interlocking, long rod-shaped microstructure. The machinable lithium disilicate material provided by the present invention has an ellipsoidal crystal structure. The unique microstructure, in which the ellipsoidal lithium disilicate grains aggregate into clusters, ensures that the restoration material has a high strength (≥300 MPa) while also being directly machinable. By controlling the composition ratio of the base glass and the heat treatment curve, the machinable lithium disilicate material has a high crystal content (total crystal content >75%) and a high light transmittance (53% to 75%). The machinable lithium disilicate material provided by the present invention not only combines the advantages of high crystal content, high transparency, high strength, and machinability, but can also be applied to abutments with excellent color and condition, without the need for special color masking but with high strength requirements, which is of great significance for improving the service life of dental restoration materials and the aesthetic restoration effect.

[0113] 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 machinable lithium disilicate material, characterized in that: The total crystal mass content of the machinable lithium disilicate material is greater than 75%, and the light transmittance is 53% to 75%. The machinable lithium disilicate material includes a crystal structure in which ellipsoidal lithium disilicate grains are aggregated into clusters. The size of the ellipsoidal lithium disilicate grains is 100 nm to 500 nm.

2. The machinable lithium disilicate material according to claim 1, characterized in that The raw materials for preparing the machinable lithium disilicate material include, in parts by weight: 58 to 82 parts of Si source; 8 to 27 parts of Li source; 1 to 5 parts of K source; 1.5 to 11.5 parts of Al source; 3 to 15 parts of P source; 0.1 to 9 parts of Ti source; and 0.6 to 8 parts of colorant. The weight of the Si source is calculated as SiO2; the weight of the Li source is calculated as Li2O; the weight of the K source is calculated as K2O; the weight of the Al source is calculated as Al2O3; the weight of the P source is calculated as P2O5; and the weight of the Ti source is calculated as TiO2.

3. The machinable lithium disilicate material according to claim 2, characterized in that The colorant includes one or more of V2O5 and rare earth oxides.

4. A method for preparing the machinable lithium disilicate material according to any one of claims 1 to 3, comprising the following steps: The raw material powders are mixed, melted for the first time and then water quenched to obtain glass slag material; The glass slag material is ball-milled and mixed, and then melted for a second time to obtain glass liquid; shaping the glass liquid to obtain a glass body; The glass body is sequentially annealed and heat-treated to obtain the machinable lithium disilicate material.

5. The preparation method according to claim 4, characterized in that The temperature of the first melting is 960° C. to 1680° C., and the holding time of the first melting is 120 min to 1080 min; The temperature of the second melting is 1400° C. to 1680° C., and the insulation time of the second melting is 30 min to 840 min.

6. The preparation method according to claim 4, characterized in that The annealing temperature is 300° C. to 550° C., and the annealing holding time is 1 hour to 18 hours.

7. The preparation method according to claim 4, characterized in that The temperature of the heat treatment is 550° C. to 950° C., and the holding time of the heat treatment is 6 min to 360 min.

8. Use of the machinable lithium disilicate material according to any one of claims 1 to 3 or the machinable lithium disilicate material prepared by the preparation method according to any one of claims 4 to 7 in the preparation of dental restoration materials.

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