Lithium disilicate glass-ceramic green body, preparation method therefor, and use thereof

Abstract

Provided are a lithium disilicate glass-ceramic green body, a preparation method therefor, and a use thereof. The lithium disilicate glass-ceramic green body comprises a lithium disilicate main crystal phase, crystal size in the lithium disilicate glass-ceramic blank being between 50 and 400 nm, and the proportion of the area of crystal grains having a length greater than 350 nm to the total area being less than 30%. The present disclosure, by means of controlling the internal crystal size of the lithium disilicate glass-ceramic green body to be below 400 nm, enables same to be directly machined without damaging the machining equipment, and combines the advantages of high strength, machinability and direct coloration. This can reduce the waiting time for patients to receive dental restorations, solve the problem of patients being unable to know the color of all-ceramic dentures before fabrication, and overcome a bottleneck for all-ceramic denture restoration materials for same-day delivery. It has great significance for achieving preoperative color matching and rapid restoration in clinical practice.

Description

A lithium disilicate glass-ceramic preform, its preparation method and application

[0001] Relevant publicly available cross-references

[0002] This disclosure claims priority to Chinese Patent 2024109990852, filed on July 24, 2024, entitled “A Lithium Disilicate Glass-Ceramic Preform and Its Preparation Method and Application,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of dental prosthesis technology, and in particular to a lithium disilicate glass-ceramic preform, its preparation method and application, especially a lithium disilicate glass-ceramic preform for dental prostheses, its preparation method and application. Background Technology

[0004] With the development of CAD / CAM (Computer-Aided Design / Computer-Aided Manufacturing) technology in recent years, the shape data of the processed dental prosthesis can be sent to a processing device for processing, enabling the rapid production of the prosthesis.

[0005] Lithium disilicate glass ceramics are a good CAD / CAM restoration material with excellent mechanical properties, translucency, and chemical stability. Its unique cross-linked and interlocked microstructure is of great significance to its mechanical properties. However, while this microstructure ensures its high strength, it also makes lithium disilicate glass ceramics unmachinable. Processing with CAD / CAM technology will cause damage to the processing tools, and the prepared restorations will have severe chipping.

[0006] US8162664B2 discloses a method for processing dental restorations using lithium disilicate "intermediate" lithium metasilicate, which makes up for the shortcomings of lithium disilicate processing. However, the dental restorations after cutting have low strength and the original color does not match the tooth color. Further heat treatment is required to convert them into lithium disilicate and then into tooth color. This increases the time cycle for restoration production, and also adds the equipment required for restoration production, thus increasing the cost.

[0007] CN113677310B discloses a processable lithium disilicate material obtained by controlling a heat treatment process. The material is characterized by the following feature: when observed under magnification within a field of view of 5 μm width and 5 μm depth, the ratio of the total area of ​​crystals with a length of 0.5 μm or more within the field of view to the area of ​​the field of view is less than 1%. However, the internal grain size distribution ranges from 0 to 0.5 μm, exhibiting a wide distribution range and uneven grain size, resulting in low strength performance of the lithium disilicate blank.

[0008] Therefore, it is necessary to develop a processable lithium disilicate dental prosthesis material with excellent strength. Summary of the Invention

[0009] To address the aforementioned technical problems, this disclosure provides a lithium disilicate glass-ceramic preform, its preparation method, and its applications. This disclosure controls the crystal size of the lithium disilicate glass-ceramic to be between 50 and 400 nm, resulting in a narrow grain size distribution and thus providing machinability. Simultaneously, it controls the proportion of grains longer than 350 nm to less than 30% of the total area, effectively avoiding the problem of poor machinability caused by large grains. Furthermore, the main crystalline phase is the lithium disilicate phase, which directly develops color, and it also possesses high strength, making it a promising candidate for application in dental restorations.

[0010] To achieve this objective, the technical solutions adopted in this disclosure include:

[0011] In a first aspect, this disclosure provides a lithium disilicate glass-ceramic preform, which includes a lithium disilicate main crystalline phase. The crystal size of the lithium disilicate glass-ceramic preform is between 50 and 400 nm, and the area of ​​grains with a length greater than 350 nm accounts for less than 30% of the total area.

[0012] The "main crystalline phase" of lithium disilicate glass-ceramic preform refers to the crystalline phase with the highest crystal precipitation rate observed by X-ray diffraction.

[0013] The crystal size is between 50 and 400 nm, for example, it can be 50 nm, 89 nm, 128 nm, 167 nm, 206 nm, 245 nm, 284 nm, 323 nm, 362 nm or 400 nm, but is not limited to the listed values. Other unlisted values ​​in this range are also applicable. Preferably, it is 100 to 390 nm, then more preferably 150 to 380 nm, and most preferably 150 to 360 nm.

[0014] The area of ​​grains with a length greater than 350 nm accounts for less than 30% of the total area. For example, it can be 29%, 28%, 27%, 26%, 25%, 22%, 20%, 19%, 18%, 17%, 15%, 12%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 2%, 1%, 0.5%, 0.2%, 0.1%, or 0%, etc., preferably less than 20%, more preferably less than 10%, even more preferably less than 5%, and even more preferably less than 1%.

[0015] The proportion of the area of ​​grains with a length greater than 350 nm to the total area in this disclosure is data obtained by observation within a magnified field of view of 10 μm × 10 μm, but it is not limited to observation only using this field of view. The entire surface of the lithium disilicate glass ceramic preform exhibits this pattern.

[0016] It is worth noting that in this disclosure, the crystal size is controlled to be between 50 and 400 nm. When the crystal size is too small, the sample strength is too low and the transparency is too high, which is not conducive to color development. When the crystal size is too large, the sample cannot be cut and processed. Furthermore, the proportion of the area of ​​crystals with a length greater than 350 nm to the total area is controlled to be less than 30%. When the area of ​​crystals with this size is too large, there is a problem of reduced cutting performance and severe edge defects of the repair.

[0017] Preferably, the flexural strength of the lithium disilicate glass-ceramic preform is greater than 300 MPa, for example, it can be 301 MPa, 335 MPa, 368 MPa, 401 MPa, 434 MPa, 468 MPa, 501 MPa, 534 MPa, 567 MPa or 600 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0018] In some alternative embodiments, the lithium disilicate main crystal phase has at least two crystal morphologies.

[0019] In some optional embodiments, the crystal morphology includes at least a first crystal morphology in which the ratio of any two of the length, width, and height is in the range of 0.6 to 1, such as 0.6, 0.7, 0.8, 0.85, 0.9, 0.95, or 1, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The crystal morphology also includes a second crystal morphology in which at least one of the length, width, and height has a ratio of 3:1 or higher, such as 3:1, 5:1, 7:1, 9:1, 11:1, 13:1, 15:1, 17:1, 19:1, or 20:1, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0020] In this disclosure, the lithium disilicate glass-ceramic preform has two overlapping crystal morphologies, which gives it high flexural strength.

[0021] In some alternative embodiments, the first crystal morphology includes any one or a combination of at least two of granular, ellipsoidal, rhomboid, or clustered shapes, wherein typical but non-limiting combinations are combinations of granular and ellipsoidal shapes, combinations of granular and rhomboid shapes, combinations of rhomboid and ellipsoidal shapes, combinations of clustered and ellipsoidal shapes, and combinations of granular and clustered shapes.

[0022] In some alternative embodiments, the second crystal morphology includes any one or a combination of at least two of the following: spindle-shaped, plate-shaped, layer-shaped, network-shaped, rod-shaped, or needle-shaped. Typical but non-limiting combinations include a combination of spindle-shaped and plate-shaped, a combination of layer-shaped and plate-shaped, a combination of spindle-shaped and layer-shaped, a combination of network-shaped and plate-shaped, a combination of spindle-shaped and network-shaped, a combination of rod-shaped and network-shaped, and a combination of spindle-shaped and needle-shaped.

[0023] In some optional embodiments, the composition content of the lithium disilicate glass-ceramic preform, by weight percentage, is as follows:

[0024] In this disclosure, SiO2 is 62% to 75%, for example, it can be 62%, 64%, 65%, 67%, 68%, 70%, 71%, 73%, 74% or 75%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Preferably, it is 63% to 74%, more preferably 64% to 73.5%.

[0025] Li2O: 8% to 18%, for example, it can be 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17% or 18%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. 10% to 18% is preferred, and 11% to 17% is more preferred.

[0026] Al2O3: 0.5% to 5%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Preferably, it is 0.5% to 4.5%, more preferably 0.5% to 4%.

[0027] This disclosure further optimizes the Al2O3 content to be controlled at 0.5% to 5%, which, in combination with the content of phosphorus pentoxide and other components, results in the final sample having lithium disilicate as the main crystalline phase. This allows for better control of crystal size uniformity and ensures that the crystal size is within a suitable range, encompassing both size uniformity and absolute size control. Ultimately, this further improves flexural strength and machinability, and reduces the proportion of edge chipping after cutting.

[0028] P2O5: 2-10%, for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Preferably, it is 2%-9%, more preferably 2.5%-8%.

[0029] In this disclosure, the P2O5 content is preferably controlled between 2% and 10%, which can simultaneously ensure the crystal size and the crystal content in the product, avoid the situation of excessive glass phase, and ultimately further improve the flexural strength and machinability.

[0030] Me(Ⅰ)2O: 1 to 10%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Preferably, it is 1.5% to 9%, more preferably 1.5% to 8%.

[0031] Me(II)O: 0.1% to 5%, for example, it can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Preferably, it is 0.1% to 2%, more preferably 0.1% to 1.5%.

[0032] In this disclosure, Me(II)O has two functions. One is to mix with Me(I)2O to achieve a mixed alkali effect, which ultimately reduces the melting temperature and thus reduces energy consumption in the subsequent melting process. The other important function is that Me(II)O can promote the precipitation of lithium disilicate with a second crystal morphology in the lithium disilicate glass ceramic preform, which then mixes with the first crystal morphology originally present in the lithium disilicate glass ceramic preform. The two have a similar effect to the combination of "steel bars and cement", which significantly improves the flexural strength of the lithium disilicate glass ceramic preform.

[0033] Colorant: 0.1% to 10%, for example, it can be 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In some alternative implementations, the mass ratio of SiO2 to Li2O is (3.5 to 7):1, for example, it can be 3.5:1, 4.1:1, 4.4:1, 4.7:1, 6.08:1, 6.74:1 or 7:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] In some alternative implementations, the mass ratio of the sum of Al2O3 and P2O5 to Li2O is (0.2 to 1):1, for example, it can be 0.2:1, 0.33:1, 0.52:1, 0.63:1, 0.72:1, 0.91:1 or 1:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] In this disclosure, Al2O3 works together with P2O5 to regulate the grain size of lithium disilicate. Therefore, the sum of the contents of the two and the mass ratio of Li2O need to be controlled within a specific range, which is more conducive to obtaining a product with a final grain size within the target range. On the other hand, the amount of Al2O3 introduced should not be too high to avoid the situation where the crystals grow further during the subsequent glazing process, resulting in a decrease in performance.

[0037] In order to obtain products with the target grain size, the present disclosure has a high P2O5 content and a low Al2O3 content, which can form more nuclei and thus reduce the final grain size. Aluminum oxide can reduce phase separation in the silicon-lithium system and increase the thermal stability of the system. At the same time, it can significantly reduce the crystal growth rate in the system, which is beneficial to improving the crystallization controllability of the system.

[0038] In some alternative implementations, Me(Ⅰ)2O comprises K2O and / or Na2O.

[0039] In some alternative embodiments, Me(Ⅱ)O comprises any one or a combination of at least two of MgO, CaO, ZnO, BaO or SrO, wherein typical but non-limiting combinations are combinations of MgO and CaO, combinations of ZnO and CaO, combinations of MgO and ZnO, combinations of BaO and CaO, combinations of MgO and BaO, combinations of SrO and BaO, and preferably at least ZnO.

[0040] In this disclosure, Me(II)O is further preferably found to contain ZnO, and the ZnO content is 0.05-5.0%, for example, it can be 0.05%, 0.06%, 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4%, 4.5%, or 5%, preferably 0.05-3.0%. The final main crystalline phase is lithium disilicate, which can simultaneously obtain two crystal morphologies, and the crystal size and ratio of the two morphologies are within a suitable range, which can better improve the cutting performance and strength.

[0041] In some alternative embodiments, the colorant comprises CeO2, V2O5, Er2O3, and Pr6O. 11 Combinations of at least two of Nd₂O₃, Fe₂O₃, Tb₄O₇, or TiO₂, wherein typical but non-limiting combinations are combinations of CeO₂ and V₂O₅, combinations of Er₂O₃ and V₂O₅, combinations of CeO₂ and Er₂O₃, and Pr₆O₃. 11 Combinations with V₂O₅, CeO₂ and Pr₆O 11 Combinations of Nd2O3 and Fe2O3, combinations of Nd2O3 and Fe2O3, combinations of Fe2O3 and V2O5, combinations of Tb4O7 and V2O5, and combinations of Fe2O3 and TiO2.

[0042] This disclosure does not impose any restrictions on the shape of the lithium disilicate glass-ceramic preform. It can adopt shapes well known to those skilled in the art, such as block, column, disc, or plate shapes, for cutting, grinding, or milling by CAD / CAM equipment. It is preferably block or disc-shaped, and more preferably block-shaped.

[0043] Generally, the dimensions of the block-shaped billet are: length between 11mm and 44mm, width between 10mm and 18mm, and height between 10mm and 18mm. Preferred block-shaped billet dimensions are 18mm×13mm×15mm, 40mm×15mm×14mm, 32mm×15mm×14mm, or 12mm×13mm×15mm.

[0044] The smallest surface of the block blank is bonded to a metal handle using organic adhesive. The metal handle is matched with the corresponding CAD / CAM cutting equipment. The block blank is fixed to the cutting equipment by the metal handle and then cut to obtain a denture of a specific shape.

[0045] In a second aspect, this disclosure provides a method for preparing a lithium disilicate glass-ceramic preform according to the first aspect. The method includes: subjecting a glass preform to a first heat treatment to obtain a lithium disilicate glass-ceramic preform; the heat treatment curve of the first heat treatment includes at least two plateau temperatures.

[0046] In some optional embodiments, the heating rate of the heat treatment curve is 1 to 10 °C / min, for example, it can be 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min or 10 °C / min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 3 to 8 °C / min.

[0047] In some optional embodiments, the first plateau temperature in the heat treatment curve is 550℃ to 670℃, for example, it can be 550℃, 564℃, 577℃, 590℃, 604℃, 617℃, 630℃, 644℃, 657℃ or 670℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The second plateau temperature is 730℃ to 850℃, for example, it can be 730℃, 744℃, 757℃, 770℃, 784℃, 797℃, 810℃, 824℃, 837℃ or 850℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] This process includes at least two plateau temperatures. Preferably, the first plateau temperature is above 500°C and below 660°C, with a holding time preferably above 10 minutes and below 300 minutes, forming the nucleus for crystal growth. The second plateau temperature is higher than the first, preferably above 700°C and below 850°C, with a holding time preferably above 10 minutes and below 100 minutes, completing crystal growth. The heating rate in this process needs to be controlled at above 1°C / min and below 10°C / min, more preferably above 3°C / min and below 8°C / min, and even more preferably above 4°C / min and below 6°C / min, to ensure the formation of uniform and fine crystals inside the blank, with crystal sizes ranging from 50 to 400 nm, making it suitable for processing.

[0049] In some alternative embodiments, the preparation of the glass preform includes: ball milling, melting, casting and cooling of the raw material powder to obtain the glass preform.

[0050] This disclosure makes no restrictions on the process flow, parameters and equipment for the ball milling, melting, casting and cooling steps, and any process flow, parameters and equipment known to those skilled in the art for the preparation of glass preforms may be used.

[0051] In the ball milling process, the raw materials are mixed evenly using ball milling equipment. The ball milling time is preferably 1 hour to ensure that the raw materials are mixed evenly.

[0052] In the melting process, the uniformly mixed powder is placed in a high-temperature furnace, preferably at a melting temperature of 1200℃ to 1580℃, thereby obtaining molten glass, such as at 1350℃, 1450℃, 1500℃ or 1580℃, etc. The preferred melting time is more than 2 hours and less than 6 hours to obtain sufficiently uniform glass liquid, such as 3 hours, 4 hours or 5 hours. The glass can also be repeatedly melted to ensure that the glass liquid is sufficiently uniform.

[0053] In the casting preparation process, the molten glass from the melting process is poured into a mold, placed in an annealing furnace, and annealed at a temperature above 350°C and below 450°C for 1 to 3 hours. Then it is cooled to room temperature to obtain the glass blank.

[0054] Thirdly, this disclosure provides an application of the lithium disilicate glass-ceramic preform of the first aspect in machining.

[0055] The processing method for the machinable high-strength lithium disilicate glass-ceramic preforms disclosed herein typically employs CAD / CAM equipment, enabling the manufacture of dentures required by dental patients in a short time. Generally, the fabrication of a single veneer involves processes such as design, cutting, sintering, grinding, and glazing / polishing. This material eliminates one sintering time step, reducing the time from 80 minutes to 55 minutes, significantly improving efficiency.

[0056] In some optional embodiments, the percentage of defective area in the lithium disilicate glass-ceramic preform after machining is less than 8%, for example, it can be 7.9%, 7.8%, 7.7%, 7.6%, 7.5%, 7.4%, 7.0%, 6.5%, 6.4%, 6.2%, 6.0%, 5.5%, 5.2%, 5.0%, 4.8%, 4.5%, 4.0%, 3.9%, 3.8%, 3.7%, 3.5%, 3.0%, 2.9%, 2.8%, 2.5%, 2.0%, 1.9%, 1.8%, 1.5%, 1.0%, 0.5%, or 0%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0057] In some alternative implementations, machining includes CAD / CAM machining.

[0058] In some alternative implementations, machining is used to form the dental prosthesis block.

[0059] In the processing steps, the lithium disilicate blank from the nucleation and crystallization process is cooled to room temperature to obtain a machinable dental restoration. The dental restoration is then machined into a denture shape using machining methods, which are not particularly limited and include cutting, grinding, etc., thus obtaining a denture.

[0060] Compared with the prior art, this disclosure has at least the following beneficial effects:

[0061] (1) The lithium disilicate glass-ceramic preform provided in this disclosure uses lithium disilicate as the main crystalline phase, and further optimizes the crystal size to be between 50 and 400 nm, so that it can be directly machined and prepared into the shape of a repair body with complete and continuous edges. The introduction of ZnO and other materials promotes the formation of two types of lithium disilicate nanoscale crystals after the nucleation and crystallization process inside the preform. The two types of nanoscale crystals are closely bonded and interlocked, which gives it excellent processing performance and excellent mechanical strength. Under preferred conditions, its flexural strength is above 300 MPa, with excellent performance and a defect area ratio of ≤8%; at the same time, it has good machinability.

[0062] (2) The preparation method of lithium disilicate glass ceramic blank provided in this disclosure has a simple manufacturing process and is easy to industrialize.

[0063] (3) The lithium disilicate glass ceramic preform provided in this disclosure has the advantages of high strength, machinability, and direct color development. It can reduce the waiting time for patients to wear teeth and can be applied to veneers, inlays, single crowns, and 3-unit bridge restorations without molars. It solves the problem of patients not knowing the color of all-ceramic dentures before tooth fabrication and breaks through the bottleneck of all-ceramic denture restoration materials that affect patients wearing teeth on the same day. It is of great significance for achieving preoperative color matching and rapid restoration in clinical practice. Attached Figure Description

[0064] Figures 1 and 2 are SEM images of the machinable lithium disilicate dental prosthesis prepared in Example 1;

[0065] Figure 3 is an XRD pattern of the machinable lithium disilicate dental restoration prepared in Example 1;

[0066] Figure 4 is the XRD pattern of the machinable lithium disilicate dental prosthesis prepared in Example 2;

[0067] Figure 5 is a SEM image of the lithium disilicate dental restoration prepared in Comparative Example 2. Detailed Implementation

[0068] To facilitate understanding of this disclosure, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of this disclosure.

[0069] It should be understood that in the description of this disclosure, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0070] Example 1

[0071] This embodiment provides a method for preparing a lithium disilicate glass-ceramic preform, which includes the following steps:

[0072] According to the mass percentage of the basic glass components, weigh out the analytically pure SiO2, Li2CO3, K2CO3, Al2O3, ZnO, (NH4)2HPO4, and TiO2. 2、 The mass percentages of the oxides corresponding to each component in CeO2 and Er2O3 are 72:15.7:3.5:1:0.15:0.2:4.55:0.5:1.8:0.6.

[0073] After weighing the raw material powder, place it in a ball mill jar and use a ball mill at a speed of 500 r / min for 1 hour to ensure uniform mixing. Place the mixed raw material in a crucible and put it in a high-temperature resistance furnace. Heat the material to 1000℃ at a rate of 10℃ / min and hold for 100 min. Then heat the material to 1500℃ at a rate of 10℃ / min and hold for 3 hours. Remove the material and cast it into a graphite mold preheated to 450℃ for 60 min. Place the mold in an annealing furnace and anneal at 400℃ for 1 hour. Then cool the mold to room temperature to obtain the glass blank.

[0074] The glass preform is placed in a crystallization furnace and heated to 630°C at a rate of 5°C / min, held for 180 min, then heated to 800°C at a rate of 5°C / min, held for 30 min, and cooled to room temperature to obtain a lithium disilicate glass-ceramic preform (i.e., a machinable lithium disilicate dental prosthesis).

[0075] The microstructure and XRD images of the lithium disilicate dental prosthesis prepared in this embodiment are shown in Figures 1-2 and 3. The lithium disilicate dental prosthesis has a crystal content of 84%, a spindle-shaped lithium disilicate grain size of 320 nm, a particulate lithium disilicate grain size of 230 nm, and a flexural strength of 360 MPa.

[0076] Example 2

[0077] This embodiment provides a method for preparing a lithium disilicate glass-ceramic preform, which includes the following steps:

[0078] According to the mass percentage of the basic glass components, weigh out the analytically pure SiO2, Li2CO3, K2CO3, Al2O3, ZnO, (NH4)2HPO4, and TiO2. 2、 The mass percentages of the oxides corresponding to each component in CeO2 and Er2O3 are 70:14.7:4:1:0.15:2.2:5.05:0.5:1.8:0.6.

[0079] After weighing the raw material powder, place it in a ball mill jar and use a ball mill at a speed of 600 r / min for 40 min to ensure uniform mixing. Place the mixed raw material in a crucible and put it in a high-temperature resistance furnace. Heat the material to 1100℃ at a rate of 15℃ / min and hold for 90 min. Then heat the material to 1560℃ at a rate of 5℃ / min and hold for 2.5 h. Remove the material and cast it into a graphite mold preheated to 500℃ for 50 min. Place the mold in an annealing furnace and anneal at 450℃ for 0.5 h. Then cool the mold to room temperature to obtain the glass preform.

[0080] The glass preform is placed in a crystallization furnace and heated to 670°C at a rate of 10°C / min, held for 120 min, then heated to 810°C at a rate of 2°C / min, held for 10 min, and cooled to room temperature to obtain a lithium disilicate glass-ceramic preform (i.e., a machinable lithium disilicate dental prosthesis).

[0081] The XRD pattern of the machinable lithium disilicate dental prosthesis prepared in this embodiment is shown in Figure 4. As can be seen from Figure 4, the quartz phase increases and the lithium disilicate crystal content decreases to 77%.

[0082] Example 3

[0083] This embodiment provides a method for preparing a lithium disilicate glass-ceramic preform, which includes the following steps:

[0084] According to the mass percentage of the basic glass components, weigh out the analytically pure SiO2, Li2CO3, K2CO3, Al2O3, ZnO, (NH4)2HPO4, and TiO2. 2、 The mass percentages of the oxides corresponding to each component in CeO2 and Er2O3 are 71.5:15.7:4:1:0.15:1.2:3.55:0.5:1.8:0.6.

[0085] After weighing the raw material powder, place it in a ball mill jar and use a ball mill at a speed of 500 r / min for 1.5 h to ensure uniform mixing. Place the mixed raw material in a crucible and put it in a high-temperature resistance furnace. Heat the material to 950℃ at a rate of 5℃ / min and hold for 200 min. Then heat the material to 1400℃ at a rate of 12℃ / min and hold for 6 h. Remove the material and cast it into a graphite mold preheated to 400℃ for 120 min. Place the mold in an annealing furnace and anneal at 350℃ for 1.5 h. Then cool the mold to room temperature to obtain the glass blank.

[0086] The glass preform is placed in a crystallization furnace and heated to 550°C at a rate of 2°C / min, held for 240 min, then heated to 730°C at a rate of 10°C / min, held for 120 min, and cooled to room temperature to obtain a lithium disilicate glass-ceramic preform (i.e., a machinable lithium disilicate dental prosthesis).

[0087] Example 4

[0088] This embodiment provides a method for preparing a lithium disilicate glass-ceramic preform, which includes the following steps:

[0089] According to the mass percentage of the basic glass components, weigh out the analytically pure SiO2, Li2CO3, K2CO3, Al2O3, ZnO, (NH4)2HPO4, and TiO2. 2、 The mass percentages of the oxides corresponding to each component in CeO2 and Er2O3 are 69:15.7:4:1:0.55:2.3:4.65:0.5:1.7:0.6. After weighing the raw material powder, place it in a ball mill jar and use a ball mill at a speed of 500 r / min for 1 hour to ensure uniform mixing. Place the mixed raw material in a crucible and put it in a high-temperature resistance furnace. Heat the material to 1000℃ at a rate of 10℃ / min and hold for 100 min. Then heat the material to 1500℃ at a rate of 10℃ / min and hold for 3 hours. Remove the material and cast it into a graphite mold preheated to 450℃ for 60 min. Place the mold in an annealing furnace and anneal at 400℃ for 1 hour. Then cool the mold to room temperature to obtain the glass blank.

[0090] The glass preform is placed in a crystallization furnace and heated to 630°C at a rate of 5°C / min, held for 180 min, then heated to 800°C at a rate of 5°C / min, held for 30 min, and cooled to room temperature to obtain a lithium disilicate glass-ceramic preform (i.e., a machinable lithium disilicate dental prosthesis).

[0091] Example 5

[0092] This embodiment provides a method for preparing a lithium disilicate glass-ceramic preform, which includes the following steps:

[0093] According to the mass percentage of the basic glass components, weigh out the analytically pure SiO2, Li2CO3, K2CO3, Al2O3, ZnO, (NH4)2HPO4, and TiO2. 2、 The mass percentages of the oxides corresponding to each component in CeO2 and Er2O3 are 70.4:15.7:3:2:0.15:1.1:4.65:0.5:2.0:0.5. After weighing the raw material powder, place it in a ball mill jar and use a ball mill at a speed of 500 r / min for 1 hour to ensure uniform mixing. Place the mixed raw material in a crucible and put it in a high-temperature resistance furnace. Heat the material to 1000℃ at a rate of 10℃ / min and hold for 100 min. Then heat the material to 1500℃ at a rate of 10℃ / min and hold for 3 hours. Remove the material and cast it into a graphite mold preheated to 450℃ for 60 min. Place the mold in an annealing furnace and anneal at 400℃ for 1 hour. Then cool the mold to room temperature to obtain the glass blank.

[0094] The glass preform is placed in a crystallization furnace and heated to 630°C at a rate of 5°C / min, held for 180 min, then heated to 800°C at a rate of 5°C / min, held for 30 min, and cooled to room temperature to obtain a lithium disilicate glass-ceramic preform (i.e., a machinable lithium disilicate dental prosthesis).

[0095] Example 6

[0096] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Example 1 except that the P2O5 content is only 1% and the remaining 3.55% is adapted to be SiO2.

[0097] Example 7

[0098] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Example 1 except that the P2O5 content is 12% and the SiO2 content is reduced by 7.45%.

[0099] Example 8

[0100] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Example 1 except that the Al2O3 content is 0.1% and the remaining 0.9% is adapted to be SiO2.

[0101] Example 9

[0102] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Example 1 except that the Al2O3 content is 8% and the SiO2 content is adapted to be reduced by 7%.

[0103] Example 10

[0104] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Example 1 except that the ZnO content is 0.05% and the remaining 0.1% is adapted to be increased to SiO2.

[0105] Example 11

[0106] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Example 1 except that the ZnO content is 6% and the SiO2 content is reduced by 5.85%.

[0107] Example 12

[0108] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as that in Embodiment 1 except that ZnO is replaced with BaO.

[0109] Example 13

[0110] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Embodiment 1 except that the glass preform is placed in a crystallization furnace and heated to 700°C at a heating rate of 5°C / min.

[0111] Example 14

[0112] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Embodiment 1 except that the glass preform is placed in a crystallization furnace and heated to 500°C at a heating rate of 5°C / min.

[0113] Example 15

[0114] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Embodiment 1 except that the second plateau temperature in the heat treatment curve is 900℃, i.e., it is heated to 900℃ at a heating rate of 5℃ / min.

[0115] Example 16

[0116] This embodiment provides a lithium disilicate glass-ceramic preform, which is the same as in Embodiment 1 except that the second plateau temperature in the heat treatment curve is 700°C, i.e., it is heated to 700°C at a heating rate of 5°C / min.

[0117] Example 17

[0118] This embodiment provides a lithium disilicate glass-ceramic preform. Except for the second plateau temperature of 850°C and holding for 5 minutes in the heat treatment curve, which is then raised to 850°C at a heating rate of 5°C / min and held for 5 minutes, the rest of the lithium disilicate glass-ceramic preform is the same as in Embodiment 1.

[0119] Comparative Example 1

[0120] This comparative example provides a lithium disilicate glass-ceramic preform, which is identical to that of Example 1 except that the ratio of SiO2:Li2O:K2O:Al2O3:ZnO:MgO:P2O5:TiO2:CeO2:Er2O3 is 68:15.2:4:2:3.5:2.2:3.2:0.4:1.0:0.5.

[0121] The SEM image of the lithium disilicate dental prosthesis prepared in this comparative example is shown in Figure 5. As can be seen from Figure 5, only one morphology of crystal phase was obtained, resulting in poor machinability.

[0122] Test methods: The crystal content and main crystalline phase of the lithium disilicate glass-ceramic green body were tested using the X-ray crystal three-point bending test. The flexural strength of the lithium disilicate glass-ceramic green body was tested using the three-point bending test method of GB30367-2013 / ISO6872:2008. The crystal morphology types of the lithium disilicate glass-ceramic green body were tested using X-ray diffraction. The crystal morphology and grain size of the lithium disilicate glass-ceramic green body were observed and tested using scanning electron microscopy. The machinability of the lithium disilicate glass-ceramic green body was tested using CAD / CAM cutting equipment (CMW-400 cutting machine) (based on the number of facets that can be cut by one set of cutting tools). The percentage of defect area after cutting the lithium disilicate glass-ceramic green body was tested using a high-definition microscope.

[0123] The test results of the above embodiments and comparative examples are shown in Table 1.

[0124] Table 1

[0125] The following points can be observed from Table 1:

[0126] (1) As can be seen from Examples 1-5, the lithium disilicate glass-ceramic preform provided in this disclosure uses lithium disilicate as the sole or main crystalline phase. Traditional lithium disilicate dental restorations have a cross-linked, interlocking long rod-shaped microstructure. The lithium disilicate glass-ceramic preform provided in this disclosure has two crystal morphologies. The two nanoscale crystal morphologies are closely fitted and cross-interlocked, giving it excellent processing performance and excellent mechanical strength, making it suitable for use as a dental restoration. Moreover, its flexural strength is above 300 MPa, exhibiting excellent performance, with a defect area ratio of ≤8%. It also has good machinability. In other words, the lithium disilicate dental restoration provided in this disclosure combines the advantages of high crystal content, high strength, and good machinability. It can be applied to veneers, inlays, single crowns, and 3-unit bridge restorations without molars, which is of great significance for improving the service life and aesthetic restoration effect of dental restoration materials.

[0127] (2) As can be seen from Examples 1 and 6 to 12, the selection and content of each component in the lithium disilicate glass-ceramic preform provided in this disclosure have a significant impact on the flexural strength and machinability of the final lithium disilicate glass-ceramic preform. The P2O5 content is preferably controlled between 2% and 10%, the final main crystalline phase of the sample is lithium disilicate, and the crystal size can be controlled within a suitable range. The final sample has high flexural strength and a small proportion of edge chipping after cutting. Similarly, the Al2O3 content is controlled between 0.5% and 5%, and the ZnO content can cooperate with other components to further improve the flexural strength of the sample and reduce the proportion of edge chipping after cutting, which has broad application prospects.

[0128] (3) As can be seen from the combined examples 1 and 13-17, the present disclosure preferably adopts a heat treatment curve with two plateau temperatures and the temperature is controlled within a reasonable range, which can better control the size and morphology of crystal growth, and finally obtain a lithium disilicate glass ceramic blank with excellent flexural strength and cutting performance.

[0129] (4) As can be seen from the combined results of Example 1 and Comparative Example 1, the Me(II)O content in Comparative Example 1 is seriously high, resulting in only one morphology of crystal phase and poor machinability. This indicates that the present disclosure can improve flexural strength and machinability by introducing two morphologies of crystal into the lithium disilicate glass-ceramic preform.

[0130] This disclosure illustrates its detailed features through the above embodiments, but it is not limited to these detailed features, meaning that this disclosure does not necessarily depend on them for implementation. Those skilled in the art should understand that any improvements to this disclosure, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods all fall within the scope of protection and disclosure of this disclosure. Industrial applicability

[0131] The method for preparing lithium disilicate glass-ceramic preforms disclosed herein is simple and easy to industrialize. The prepared lithium disilicate glass-ceramic preforms have advantages such as high strength, machinability, and direct color development, which can reduce the waiting time for patients to wear teeth. It can be applied to veneers, inlays, single crowns, and 3-unit bridge restorations without molars, solving the problem of patients not knowing the color of all-ceramic prostheses before tooth fabrication. It breaks through the bottleneck of all-ceramic prosthesis restoration materials that affect patients wearing teeth on the same day, and is of great significance for achieving preoperative color matching and rapid restoration in clinical practice.

Claims

1. A lithium disilicate glass-ceramic body, characterized in that, The lithium disilicate glass ceramic blank comprises a lithium disilicate main crystal phase, the area ratio of the crystal grains with a size of 50-400 nm and a length of more than 350 nm in the lithium disilicate glass ceramic blank is less than 30%.

2. The lithium disilicate glass-ceramic body according to claim 1, characterized in that The bending strength of the lithium disilicate glass ceramic blank is greater than 300 MPa.

3. The lithium disilicate glass-ceramic body according to claim 1 or 2, characterized in that The lithium disilicate main crystal phase has at least two crystal morphologies.

4. The lithium disilicate glass-ceramic body according to claim 3, characterized in that The crystal morphologies at least include a first crystal morphology with a ratio of any two of length, width and height in the range of 0.6-1, and a second crystal morphology with a ratio of at least two of length, width and height greater than 3:

1.

5. The lithium disilicate glass-ceramic body according to claim 4, characterized in that The first crystal morphology includes any one or a combination of at least two of a particle shape, an ellipsoidal shape, a rhombic shape or a cluster shape.

6. The lithium disilicate glass-ceramic body according to claim 4 or 5, characterized in that The second crystal morphology includes any one or a combination of at least two of a spindle shape, a sheet shape, a layer shape, a net shape, a rod shape or a needle shape.

7. The lithium disilicate glass-ceramic body according to any one of claims 1 to 6, characterized in that The lithium disilicate glass-ceramic body has a composition, in terms of percent by mass, of:

8. The lithium disilicate glass-ceramic body according to claim 7, characterized in that The mass ratio of SiO2 to Li2O is (3.5-7):

1.

9. The lithium disilicate glass-ceramic body according to claim 8, characterized in that The mass ratio of the sum of Al2O3 and P2O5 to Li2O is (0.2-1):

1.

10. The lithium disilicate glass-ceramic body according to any one of claims 7 to 9, characterized in that The Me(I)2O comprises K2O and / or Na2O.

11. The lithium disilicate glass-ceramic body according to any one of claims 7 to 10, characterized in that The Me(II)O comprises any one or a combination of at least two of MgO, CaO, ZnO, BaO or SrO.

12. The lithium disilicate glass-ceramic body of claim 11, wherein, The Me(II)O at least comprises ZnO.

13. The lithium disilicate glass-ceramic body according to any one of claims 7 to 12, characterized in that The colorant comprises a combination of at least two of Ce02, V205, Er203, Pr60 11 , Nd203, Fe203, Tb407, or Ti02.

14. A method of making a lithium disilicate glass-ceramic body according to any one of claims 1 to 13, characterized in that, The preparation method comprises: subjecting a glass blank to a first heat treatment to obtain a lithium disilicate glass ceramic blank; and the heat treatment curve of the first heat treatment comprises at least two platform temperatures.

15. The preparation method according to claim 14, characterized in that, The heating rate of the heat treatment curve is 1-10 ℃ / min.

16. The method of claim 15, wherein, The heating rate of the heat treatment curve is 3-8 ℃ / min.

17. The method of any one of claims 14 to 16, wherein the method further comprises the step of: The first platform temperature in the heat treatment curve is 550-670 ℃, and the second platform temperature is 730-850 ℃.

18. Use of the lithium disilicate glass ceramic blank according to any one of claims 1-13 in mechanical processing.

19. Use according to claim 18, characterized in that, The area ratio of the defect area of the lithium disilicate glass ceramic blank after mechanical processing is less than 8%.

20. Use according to claim 18 or 19, characterized in that, The mechanical processing comprises CAD / CAM processing.

21. Use according to any one of claims 18 to 20, characterized in that, The mechanical processing is used for forming a block for dental restoration. The lithium disilicate glass ceramic blank comprises a lithium disilicate main crystal phase, the area ratio of the crystal grains with a size of 50-400 nm and a length of more than 350 nm in the lithium disilicate glass ceramic blank is less than 30%. The bending strength of the lithium disilicate glass ceramic blank is greater than 300 MPa. The lithium disilicate main crystal phase has at least two crystal morphologies. The crystal morphologies at least include a first crystal morphology with a ratio of any two of length, width and height in the range of 0.6-1, and a second crystal morphology with a ratio of at least two of length, width and height greater than 3:

1. The first crystal morphology includes any one or a combination of at least two of a particle shape, an ellipsoidal shape, a rhombic shape or a cluster shape. The second crystal morphology includes any one or a combination of at least two of a spindle shape, a sheet shape, a layer shape, a net shape, a rod shape or a needle shape. The mass ratio of SiO2 to Li2O is (3.5-7):

1. The mass ratio of the sum of Al2O3 and P2O5 to Li2O is (0.2-1):

1. The Me(I)2O comprises K2O and / or Na2O. The Me(II)O comprises any one or a combination of at least two of MgO, CaO, ZnO, BaO or SrO. The Me(II)O at least comprises ZnO. The preparation method comprises: subjecting a glass blank to a first heat treatment to obtain a lithium disilicate glass ceramic blank; and the heat treatment curve of the first heat treatment comprises at least two platform temperatures. The heating rate of the heat treatment curve is 1-10 ℃ / min. The heating rate of the heat treatment curve is 3-8 ℃ / min. The first platform temperature in the heat treatment curve is 550-670 ℃, and the second platform temperature is 730-850 ℃.

18. Use of the lithium disilicate glass ceramic blank according to any one of claims 1-13 in mechanical processing. The area ratio of the defect area of the lithium disilicate glass ceramic blank after mechanical processing is less than 8%. The mechanical processing comprises CAD / CAM processing. The mechanical processing is used for forming a block for dental restoration.

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