CN115417600B - Lithium disilicate glass ceramic bracket and preparation method thereof - Google Patents

Abstract

The invention discloses a lithium disilicate glass ceramic bracket and a preparation method thereof, and relates to the technical field of artificial tooth materials. The preparation method comprises the following steps: (1) Lithium disilicate glass ceramic powder, acrylic ester, polyethylene glycol and photo-curing resin are mixed according to the following proportion (4-8): (0.01-0.2): (0.05-0.8): (0.5-1.5) and evenly mixing to obtain slurry; (2) Photo-curing, printing and forming the slurry to obtain a dental bracket blank; (3) And (3) discharging glue and sintering the bracket blank to obtain a finished product of the lithium disilicate glass ceramic bracket. By implementing the invention, the lithium disilicate glass ceramic bracket with high shape and position dimensional accuracy and excellent mechanical property can be obtained; the preparation method has high production efficiency and low cost.

Description

Lithium disilicate glass ceramic bracket and preparation method thereof

Technical Field

The present invention relates to the technical field of artificial tooth materials, and in particular to a lithium disilicate glass ceramic bracket and a preparation method thereof.

Background technique

Lithium disilicate glass ceramic is a commonly used dental restoration material. It has both the high transparency of glass and the high strength of ceramic. It can meet the requirements of dental materials for aesthetics and mechanical properties, and occupies an important position in the field of dental restoration. The products based on lithium disilicate glass ceramic currently used in clinical practice are mainly the Ivoka IPSe.maxCAD series. The main preparation process is melt injection molding, that is, pouring the glass melt into the concave mold under high temperature to form it, and then performing crystallization treatment after forming. Other patents related to the preparation of lithium disilicate products, such as CN104108883A discloses a high-strength lithium disilicate glass ceramic and a preparation method thereof, the process flow includes selecting an initial raw material formula and mixing them evenly, then placing them in a crucible and melting them at 1300-1600°C for 1-24 hours, then rapidly cooling them to obtain a matrix glass, and then heat-treating the matrix glass to crystallize it to obtain a glass ceramic whose main crystalline phase is lithium disilicate; for another example, patent CN108751721A discloses a lithium disilicate glass ceramic for dental zirconia surface decoration porcelain and a preparation method and application thereof, the process flow includes mixing and melting the raw materials to obtain a molten material, then pouring the molten material into a mold for annealing to obtain a glass blank, and the blank is again crystallized to obtain a lithium disilicate glass ceramic.

From the above introduction, it can be seen that traditional glass ceramic dental restoration products are obtained through high-temperature melt injection molding and subsequent crystallization treatment. The crystallization treatment is to generate lithium disilicate crystal phase and improve the mechanical properties and chemical stability of glass ceramics, because the crystal phase has better mechanical and chemical stability than amorphous glass. There are two problems with this process flow. First, when it is necessary to prepare complex shapes, especially dental products with internal structures and internal and external interconnected structures, such as dental orthodontic brackets, it is impossible to form them in one step through the mold, and later processing is required, which is time-consuming and labor-intensive, with low precision and low yield rate; on the other hand, the lithium disilicate glass ceramics currently prepared based on the glass melt post-crystallization process have a high glass phase content, resulting in low chemical and mechanical stability of lithium disilicate products. It is necessary to further increase the content of lithium disilicate ceramic crystal phase in lithium disilicate glass ceramics.

Summary of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a lithium disilicate glass-ceramic bracket. The dental bracket product prepared thereby has the advantages of high shape and size accuracy and good mechanical properties, and the preparation method of the present invention has high production efficiency.

Another technical problem to be solved by the present invention is to provide a lithium disilicate glass ceramic bracket.

In order to solve the above problems, the present invention discloses a method for preparing a lithium disilicate glass ceramic dental bracket, which comprises the following steps:

(1) mixing lithium disilicate glass ceramic powder, acrylate, polyethylene glycol, and light-curable resin in a ratio of (4-8): (0.01-0.2): (0.05-0.8): (0.5-1.5) to obtain a slurry;

(2) curing the slurry by photocuring printing to obtain a dental bracket blank;

(3) Debinding and sintering the bracket blank to obtain a finished lithium disilicate glass ceramic bracket.

As an improvement of the above technical solution, the preparation method of the lithium disilicate glass ceramic powder is:

1) dispersing a silicon source reagent and a lithium source reagent in a dispersant at a silicon-to-lithium molar ratio of (0.5-2):1 to obtain a precursor solution;

2) adding an initiator to the precursor solution to convert the precursor solution into a gel solution;

3) drying and grinding the gel solution to obtain a precursor powder;

4) heat treating the precursor powder at 600-1000° C. for 0.5-10 h, and grinding the precursor powder to a particle size of ≤200 mesh after cooling to obtain a finished lithium disilicate glass ceramic powder.

As an improvement of the above technical solution, the silicon source reagent is selected from one or more of tetraethyl orthosilicate, silicate, silica sol, hexamethyldisiloxane; the lithium source reagent is selected from alkyl lithium and/or alcohol lithium.

As an improvement of the above technical solution, the initiator is selected from one or more of water, polyvinyl alcohol, a water-ethanol mixture, a water-acetone mixture, a water-isopropanol mixture, and polyethylene glycol;

The dosage of the initiator is 0.1-10% of the volume of the precursor solution.

As an improvement of the above technical solution, in step 1), the silicon source reagent and the lithium source reagent are dispersed in a dispersant at a silicon-lithium molar ratio of (0.5-2):1, and stirred at a stirring speed of 100-1000 rpm for 12-36 hours to obtain a precursor solution;

Wherein, the dispersant is water and/or ethanol.

As an improvement of the above technical solution, the acrylic acid ester is selected from one or more of methyl acrylate, ethyl acrylate, octyl acrylate, lauryl acrylate, and 1,6-hexanediol diacrylate;

The molecular weight of the polyethylene glycol is 200-2000 g/mol.

As an improvement of the above technical solution, the acrylic ester is lauryl acrylate.

As an improvement of the above technical solution, the molecular weight of the polyethylene glycol is 1000-2000 g/mol.

As an improvement of the above technical solution, step (3) includes:

(3.1) debinding the dental bracket blank; wherein the temperature curve used for debinding is: heating to 400-800° C. at a heating rate of 0.1-10° C./min, and maintaining the temperature at 400-800° C. for 0.5-10 h;

(3.2) Sintering the dental bracket blank after debinding; wherein the temperature curve used for sintering is: heating to 800-1250° C. at a heating rate of 0.5-20° C./min, and keeping at 800-1250° C. for 0.5-10 h.

Correspondingly, the present invention also discloses a lithium disilicate glass ceramic bracket, which is prepared by adopting the above-mentioned preparation method of the lithium disilicate glass ceramic bracket.

The implementation of the present invention has the following beneficial effects:

1. The preparation method of the dental orthodontic bracket of the present invention adopts the light-curing printing 3D printing method to form a lithium disilicate glass-ceramic bracket with a complex shape, which has high dimensional accuracy, excellent aesthetic performance, short preparation process and high production efficiency.

2. The preparation method of the lithium disilicate glass ceramic bracket of the present invention is to obtain a slurry by mixing lithium disilicate glass ceramic powder, acrylate, polyethylene glycol, and photocurable resin in a specific proportion, which can meet the slurry performance requirements of photocuring printing and has a high solid phase ratio (>80wt%), effectively improving the strength of the dental bracket product.

3. The present invention prepares lithium disilicate glass ceramic powder by a sol-gel method. Firstly, the finished product is mostly spherical and absorbs less slurry, thereby effectively ensuring that the high solid phase ratio slurry maintains relatively good fluidity and shear thinning properties. Secondly, the process increases the content of the crystalline phase in lithium disilicate glass ceramics, thereby improving the mechanical stability and chemical resistance of the glass ceramics, that is, improving the mechanical properties and chemical resistance of dental bracket products.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an electron microscope image of the lithium disilicate glass ceramic powder obtained in Example 6 of the present invention;

FIG2 is a viscosity curve of the slurry obtained in Example 6 of the present invention;

FIG. 3 is a structural diagram of a dental bracket in embodiments 1 to 7 of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below.

The present invention provides a method for preparing a lithium disilicate glass ceramic bracket, which comprises the following steps:

S1: mixing lithium disilicate glass ceramic powder, acrylate, polyethylene glycol, and light-curable resin in a ratio of (4-8): (0.01-0.2): (0.05-0.8): (0.5-1.5) to obtain a slurry;

The lithium disilicate glass ceramic powder may be a glass ceramic powder obtained by traditional melting, rapid cooling, and heat treatment, or may be a lithium disilicate glass ceramic powder prepared by a sol-gel method. Preferably, in one embodiment of the present invention, the lithium disilicate glass ceramic powder is prepared by a sol-gel method, which specifically includes the following steps:

S100: dispersing a silicon source reagent and a lithium source reagent in a dispersant to obtain a precursor solution;

Among them, the silicon source reagent is a reactive reagent containing silicon element, exemplified by one or more of tetraethyl orthosilicate, silicate, silica sol, hexamethyldisiloxane, but not limited thereto. Preferably, the silicon source reagent is tetraethyl orthosilicate. The lithium source reagent is a reactive reagent containing lithium element, such as alkyl lithium (methyl lithium, ethyl lithium, butyl lithium, pentyl lithium, etc.), alcohol lithium (lithium ethoxide, lithium methanol, lithium isopropoxide, etc.), but not limited thereto. Preferably, lithium ethoxide. The dispersant can be water and/or ethanol, but not limited thereto. Preferably, ethanol.

The molar ratio of silicon in the silicon source reagent to lithium in the lithium source reagent is (0.5-2):1, exemplified by 0.8:1, 1:1, 1.3:1, 1.5:1, 1.7:1 or 1.8:1, but not limited thereto.

Specifically, after dispersion, stirring is performed at a stirring speed of 100 to 1000 rpm for 12 to 36 hours to obtain a precursor solution.

S200: adding an initiator to the precursor solution to convert the precursor solution into a gel solution;

Specifically, the initiator can be selected from one or more of water, polyvinyl alcohol, water-ethanol mixture, water-acetone mixture, water-isopropanol mixture, and polyethylene glycol. The amount of the initiator used is 0.1-10% of the volume of the precursor solution.

S300: drying and grinding the gel liquid to obtain a precursor powder;

Specifically, the gel solution is dried at 40-180° C., and after drying, ground until it is not compacted, thereby obtaining a precursor powder.

S400: heat-treating the precursor powder at 600-1000° C. for 0.5-10 h, grinding the precursor powder to a particle size of ≤200 mesh after cooling, and obtaining a finished lithium disilicate glass ceramic powder.

Based on the above preparation method, the prepared lithium disilicate is mainly spherical in microscopic morphology, has less slurry absorption, and can be combined with acrylate, polyethylene glycol, photocurable resin, etc. to form a slurry with reasonable rheological properties and a solid phase rate of more than 85%, thereby improving the various properties of dental brackets.

Specifically, in the slurry formula, the acrylate can be selected from one or more of methyl acrylate, ethyl acrylate, octyl acrylate, lauryl acrylate, and 1,6-hexanediol diacrylate, but is not limited thereto. The above-mentioned acrylate can be combined with polyethylene glycol to form a slurry with stable performance. The slurry has suitable viscoelasticity and viscosity, which can meet the fluidity requirements of photocuring printing and provide a good foundation for stable printing. Preferably, the acrylate is lauryl acrylate. The slurry formed by lauryl acrylate can maintain a good pore structure during the placement process, preventing _O2 from entering the slurry during the mixing process from escaping, resulting in difficulty in curing and reducing printing accuracy.

Specifically, the molecular weight of polyethylene glycol is 200 to 2000 g/mol, exemplified by 200 g/mol, 400 g/mol, 600 g/mol, 1000 g/mol, 1500 g/mol or 1800 g/mol, but not limited thereto. Preferably, the molecular weight of polyethylene glycol is 1000 to 2000 g/mol. Based on polyethylene glycol in this molecular weight range, the thixotropic property of the obtained slurry is better (i.e., it still has good performance after being placed for a certain period of time), thereby effectively preventing defects such as layer cracking, collapse, and missing during printing.

The photocurable resin is a common UV-curable resin in the art, such as: Lancolu L-6114 standard UV epoxy acrylic resin, Vitus WDS-2255 bisphenol A modified epoxy propylene resin, Huakai HL-183C70 novolac epoxy acrylate, BASF Joncryl 848 epoxy acrylic resin.

Among them, the usage ratio of lithium disilicate glass ceramic powder, cellulose ester, polyethylene imine, photocurable resin, and water is (4-8): (0.01-0.2): (0.05-0.8): (0.5-1.5): (0.1-1.5). The slurry obtained based on the above ratio has no agglomeration or caking, has reasonable fluidity, and has a high solid content (≥80wt%), which can well meet the needs of photocuring printing. Preferably, the usage ratio of lithium disilicate glass ceramic powder, acrylate, polyethylene glycol, and photocurable resin is (6-8): (0.01-0.1): (0.05-0.3): (0.5-1.5). The slurry obtained based on the above ratio has a higher solid content and better mechanical properties of the dental bracket.

S2: printing the slurry by photocuring to obtain a dental bracket blank;

Among them, a common light-curing printing 3D printer can be used for molding. Preferably, in one embodiment of the present invention, a pull-down ceramic 3D printing device is used for molding. Preferably, the ADT-ZP-DLP series 3D printer produced by Shenzhen Qiyu Technology Co., Ltd. is used for molding. This series of 3D printers adopts a "dual cylinder-sinking-scraping" structure, which greatly reduces the demand for slurry fluidity, and can improve printing accuracy and reduce slurry consumption.

S3: debinding and sintering the bracket blank to obtain a finished lithium disilicate glass ceramic bracket;

Specifically, S3 includes:

S31: debinding the dental bracket blank;

The temperature curve used for debinding is: heating to 400-800°C at a heating rate of 0.1-10°C/min, and keeping at 400-800°C for 0.5-10h;

Exemplarily, the binder removal heating rate is 0.2°C/min, 0.5°C/min, 1°C/min, 2°C/min, 4°C/min, 5°C/min or 8°C/min, but is not limited thereto. When the heating rate is greater than 10°C/min, the binder removal rate is too fast, which may easily cause cracking of the blank. When the heating rate is less than 0.5°C, the binder removal rate is too slow.

S32: sintering the dental bracket blank after debinding; wherein the temperature curve used for sintering is: heating to 800-1250° C. at a heating rate of 0.5-20° C./min, and keeping at 800-1250° C. for 0.5-10 hours.

The present invention is further described below with reference to specific examples. It should be noted that the printing device used in the following examples is Adventure 3D-ZP Printer-192-50 (Shenzhen Qiyu Technology Co., Ltd.). The structure of the prepared dental bracket is shown in FIG3 .

Example 1

This embodiment provides a method for preparing a lithium disilicate glass ceramic bracket, which comprises:

(1) lithium disilicate glass ceramic powder, octyl acrylate, polyethylene glycol 200 (molecular weight 200 g/mol), and photocurable resin are uniformly mixed in a ratio of 4:0.01:0.05:0.5 to obtain a slurry; specifically, the lithium disilicate glass ceramic powder is prepared by the preparation method of CN108751721A, and after the preparation, it is crushed and passed through a 2000 mesh sieve;

(2) curing the slurry by photocuring printing to obtain a dental bracket blank;

(3) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in the air. The debinding method is: heating to 300°C at 0.5°C/min and keeping it for 1 hour, then heating to 480°C at 0.5°C/min and keeping it for 2 hours, and finally heating to 600°C at 1°C/min and keeping it for 1 hour, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in the air. The specific sintering method is: heating to 600°C at 5°C/min and keeping it for 1 hour, then heating to 1000°C at 2°C/min and keeping it for 2 hours. After cooling, the lithium disilicate glass ceramic dental bracket is obtained.

Example 2

(1) Ethyl orthosilicate and lithium ethoxide were dissolved in ethanol to form 2 mol/L and 0.82 mol/L homogeneous transparent solutions, respectively. The two solutions were mixed in a silicon to lithium element molar ratio of 1:1 and stirred at a speed of 500 r/min for 12 h to obtain a homogeneous solution.

(2) adding an initiator (water: ethanol = 1:1 (weight ratio), the amount added is 1 vol% of the solution volume) to form a gel;

(3) The gel was transferred to an oven at 60°C and kept warm for 12 hours, and then completely dried in an oven at 90°C. The dried gel was ground to obtain a precursor powder;

(4) The precursor powder is heat treated by heating to 600°C at 3°C/min and then keeping the temperature for 1 hour, and then heating to 800°C at 2°C/min and keeping the temperature for 2 hours. The heat-treated powder is ball-milled in a planetary ball mill at a speed of 400 r/min for 1 hour, and passed through a 2000-mesh sieve to obtain lithium disilicate glass ceramic powder.

(5) mixing lithium disilicate glass ceramic powder, octyl acrylate, polyethylene glycol 400 (molecular weight 400 g/mol), and light-curable resin in a ratio of 4:0.01:0.05:0.5 to obtain a slurry;

(6) curing the slurry by photocuring printing to obtain a dental bracket blank;

(7) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in air. The debinding method is: heating to 300°C at 0.5°C/min and keeping it for 1 hour, then heating to 480°C at 0.5°C/min and keeping it for 2 hours, and finally heating to 600°C at 1°C/min and keeping it for 1 hour, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in air. The specific sintering method is: heating to 600°C at 5°C/min and keeping it for 1 hour, then heating to 1000°C at 2°C/min and keeping it for 2 hours. After cooling, the lithium disilicate glass ceramic dental bracket is obtained.

Example 3

(1) Ethyl orthosilicate and lithium ethoxide were dissolved in ethanol to form 2 mol/L and 0.82 mol/L homogeneous transparent solutions, respectively. The two solutions were mixed in a silicon to lithium element molar ratio of 1:1 and stirred at a speed of 500 r/min for 12 h to obtain a homogeneous solution.

(2) adding an initiator (water: ethanol = 2:1 (weight ratio), the amount added is 3 vol% of the solution volume) to form a gel;

(3) The gel was transferred to an oven at 60°C and kept warm for 12 hours, and then completely dried in an oven at 90°C. The dried gel was ground to obtain a precursor powder;

(4) The precursor powder is heat treated by heating to 600°C at 3°C/min and then keeping the temperature for 1 hour, and then heating to 800°C at 2°C/min and keeping the temperature for 2 hours. The heat-treated powder is ball-milled in a planetary ball mill at a speed of 400 r/min for 1 hour, and passed through a 2000-mesh sieve to obtain lithium disilicate glass ceramic powder.

(5) mixing lithium disilicate glass ceramic powder, octyl acrylate, polyethylene glycol 200 (molecular weight 200 g/mol), and light-curable resin in a ratio of 8:0.2:0.8:1.5 to obtain a slurry;

(6) curing the slurry by photocuring printing to obtain a dental bracket blank;

(7) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in air. The debinding method is: heating to 300°C at 0.5°C/min and keeping it for 1 hour, then heating to 480°C at 0.5°C/min and keeping it for 2 hours, and finally heating to 600°C at 1°C/min and keeping it for 1 hour, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in air. The specific sintering method is: heating to 600°C at 5°C/min and keeping it for 1 hour, then heating to 1000°C at 2°C/min and keeping it for 2 hours. After cooling, the lithium disilicate glass ceramic dental bracket is obtained.

Example 4

(1) Ethyl orthosilicate and lithium ethoxide were dissolved in ethanol to form 2 mol/L and 0.82 mol/L homogeneous transparent solutions, respectively. The two solutions were mixed in a silicon to lithium element molar ratio of 1:1 and stirred at a speed of 500 r/min for 12 h to obtain a homogeneous solution.

(2) adding an initiator (water: ethanol = 2:1 (weight ratio), the amount added is 3 vol% of the solution volume) to form a gel;

(3) The gel was transferred to an oven at 60°C and kept warm for 12 hours, and then completely dried in an oven at 90°C. The dried gel was ground to obtain a precursor powder;

(4) The precursor powder is heat treated by heating to 600°C at 3°C/min and then keeping the temperature for 1 hour, and then heating to 800°C at 2°C/min and keeping the temperature for 2 hours. The heat-treated powder is ball milled in a planetary ball mill at a speed of 400 r/min for 1 hour, and passed through a 2000-mesh sieve to obtain lithium disilicate glass ceramic powder;

(5) mixing lithium disilicate glass ceramic powder, lauryl acrylate, polyethylene glycol 200 (molecular weight 200 g/mol), and light-curable resin in a ratio of 8:0.08:0.4:1.2 to obtain a slurry;

(6) curing the slurry by photocuring printing to obtain a dental bracket blank;

(7) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in air. The debinding method is: heating to 300°C at 0.5°C/min and keeping it for 1 hour, then heating to 480°C at 0.5°C/min and keeping it for 2 hours, and finally heating to 600°C at 1°C/min and keeping it for 1 hour, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in air. The specific sintering method is: heating to 600°C at 5°C/min and keeping it for 1 hour, then heating to 1000°C at 2°C/min and keeping it for 2 hours. After cooling, the lithium disilicate glass ceramic dental bracket is obtained.

Example 5

(1) Ethyl orthosilicate and lithium ethoxide were dissolved in ethanol to form 2 mol/L and 0.82 mol/L homogeneous transparent solutions, respectively. The two solutions were mixed in a silicon to lithium element molar ratio of 1:1 and stirred at a speed of 500 r/min for 12 h to obtain a homogeneous solution.

(2) adding an initiator (water: ethanol = 2:1 (weight ratio), the amount added is 3 vol% of the solution volume) to form a gel;

(3) The gel was transferred to an oven at 60°C and kept warm for 12 hours, and then completely dried in an oven at 90°C. The dried gel was ground to obtain a precursor powder;

(4) The precursor powder is heat treated by heating to 600°C at 3°C/min and then keeping the temperature for 1 hour, and then heating to 800°C at 2°C/min and keeping the temperature for 2 hours. The heat-treated powder is ball milled in a planetary ball mill at a speed of 400 r/min for 1 hour, and passed through a 2000-mesh sieve to obtain lithium disilicate glass ceramic powder;

(5) mixing lithium disilicate glass ceramic powder, lauryl acrylate, polyethylene glycol 200 (molecular weight 200 g/mol), and light-curable resin in a ratio of 8:0.08:0.4:1.2 to obtain a slurry;

(6) curing the slurry by photocuring printing to obtain a dental bracket blank;

(7) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in air. The debinding method is: heating to 300°C at 0.5°C/min and keeping it for 1 hour, then heating to 480°C at 0.5°C/min and keeping it for 2 hours, and finally heating to 600°C at 1°C/min and keeping it for 1 hour, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in air. The specific sintering method is: heating to 600°C at 5°C/min and keeping it for 1 hour, then heating to 1000°C at 2°C/min and keeping it for 2 hours. After cooling, the lithium disilicate glass ceramic dental bracket is obtained.

Example 6

(1) Ethyl orthosilicate and lithium ethoxide were dissolved in ethanol to form 2 mol/L and 0.82 mol/L homogeneous transparent solutions, respectively. The two solutions were mixed in a silicon to lithium element molar ratio of 1:1 and stirred at a speed of 500 r/min for 12 h to obtain a homogeneous solution.

(2) adding an initiator (water: ethanol = 2:1 (weight ratio), the amount added is 3 vol% of the solution volume) to form a gel;

(3) The gel was transferred to an oven at 60°C and kept warm for 12 hours, and then completely dried in an oven at 90°C. The dried gel was ground to obtain a precursor powder;

(4) The precursor powder is heat treated by heating to 600°C at 3°C/min and then keeping the temperature for 1 hour, and then heating to 800°C at 2°C/min and keeping the temperature for 2 hours. The heat-treated powder is ball-milled in a planetary ball mill at a speed of 400 r/min for 1 hour, and passed through a 2000-mesh sieve to obtain lithium disilicate glass ceramic powder.

(5) mixing lithium disilicate glass ceramic powder, lauryl acrylate, polyethylene glycol 1000 (molecular weight 1000 g/mol), and light-curable resin in a ratio of 8:0.08:0.4:1.2 to obtain a slurry;

(6) curing the slurry by photocuring printing to obtain a dental bracket blank;

(7) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in air. The debinding method is: heating to 300°C at 0.5°C/min and keeping it for 1 hour, then heating to 480°C at 0.5°C/min and keeping it for 2 hours, and finally heating to 600°C at 1°C/min and keeping it for 1 hour, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in air. The specific sintering method is: heating to 600°C at 5°C/min and keeping it for 1 hour, then heating to 1000°C at 2°C/min and keeping it for 2 hours. After cooling, the lithium disilicate glass ceramic dental bracket is obtained.

Example 7

(1) Ethyl orthosilicate and tert-butyl lithium were dissolved in ethanol to form 1 mol/L and 0.5 mol/L homogeneous transparent solutions, respectively. The two solutions were mixed in a silicon to lithium element molar ratio of 1.2:1 and stirred at a speed of 500 r/min for 8 h to obtain a homogeneous solution.

(2) adding (water: acetone = 1:1 (weight ratio), the amount added is 5 vol% of the solution volume) to form a gel;

(3) transferring the gel to an oven at 70° C. and keeping the temperature for 24 hours, and then completely drying the gel in an oven at 120° C., and grinding the dried gel to obtain a precursor powder;

(4) The precursor powder is heat treated by heating to 500°C at 1°C/min and then keeping the temperature for 2 h, then heating to 750°C at 1°C/min and keeping the temperature for 3 h. The heat treated powder is ball milled in a planetary ball mill at a speed of 500 r/min for 2 h, and passed through a 1000-mesh sieve to obtain lithium disilicate glass ceramic powder.

(5) mixing lithium disilicate glass ceramic powder, lauryl acrylate, polyethylene glycol 2000 (molecular weight 2000 g/mol), and light-curable resin in a ratio of 6:0.05:0.3:1.1 to obtain a slurry;

(6) curing the slurry by photocuring printing to obtain a dental bracket blank;

(7) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in air. The debinding method is: heating to 240°C at 1°C/min and keeping it for 1 hour, then heating to 380°C at 1°C/min and keeping it for 1 hour, then heating to 470°C at 0.5°C/min and keeping it for 2 hours, and finally heating to 600°C at 1°C/min and keeping it for 1 hour, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in a vacuum. The specific sintering method is: heating to 600°C at 2°C/min and keeping it for 1 hour, then heating to 1200°C at 1°C/min and keeping it for 2 hours. After cooling, a lithium disilicate glass ceramic bracket is obtained.

Example 8

(1) Hexamethyldisiloxane and ethyllithium were dissolved in ethanol to form 3 mol/L and 1 mol/L homogeneous transparent solutions, respectively. The two solutions were mixed in a molar ratio of silicon to lithium of 1:1 and stirred at a speed of 800 r/min for 24 h to obtain a homogeneous solution.

(2) adding (water: isopropanol = 1:1 (weight ratio), the added amount is 8 vol% of the solution volume) to form a gel;

(3) transferring the gel to an oven at 50° C. and keeping the temperature for 18 hours, and then completely drying the gel in an oven at 150° C., and grinding the dried gel to obtain a precursor powder;

(4) The precursor powder is heat treated by heating to 400°C at 1°C/min and then keeping the temperature for 2h, then heating to 600°C at 1°C/min and then keeping the temperature for 2h, then heating to 800°C at 0.5°C/min and keeping the temperature for 2h. The heat-treated powder is ball milled at a speed of 300 r/min for 4h in a planetary ball mill and passed through a 3000-mesh sieve to obtain lithium disilicate glass ceramic powder.

(5) mixing lithium disilicate glass ceramic powder, lauryl acrylate, polyethylene glycol 1600 (molecular weight 1600 g/mol), and light-curable resin in a ratio of 7:0.05:0.25:0.9 to obtain a slurry;

(6) curing the slurry by photocuring printing to obtain a dental bracket blank;

(7) The dental bracket blank is placed in a low-temperature ceramic furnace for debinding in air. The debinding method is: heating to 260°C at 1°C/min and keeping it for 0.5h, then heating to 360°C at 1°C/min and keeping it for 2h, then heating to 470°C at 1°C/min and keeping it for 2h, and finally heating to 600°C at 1°C/min and keeping it for 2h, and then cooling to complete the debinding process. Next, the bracket after debinding will be placed in a high-temperature furnace and sintered in a nitrogen atmosphere. The specific sintering method is: heating to 600°C at 2°C/min and keeping it for 1h, then heating to 1200°C at 1°C/min and keeping it for 2h. After cooling, a lithium disilicate glass ceramic bracket is obtained.

The lithium disilicate glass ceramic brackets of Examples 1 to 7 were tested as follows:

(1) Fracture toughness: measured in accordance with GB/T 23806-2009 Test method for fracture toughness of fine ceramics - single edge precracked beam (SEPB) method;

(2) Hardness: Determined in accordance with GB/T 16534-2009 - Test method for room temperature hardness of fine ceramics;

(3) Light transmittance: measured in accordance with JC/T 2020-2010 - Test method for light transmittance of translucent fine ceramics;

(4) Determination of printing yield rate: 100 pieces were printed for each example. If there were any defects such as collapse or missing during the printing process, it was considered unqualified. After the finished product was debonded, if there was any layer cracking, it was considered unqualified.

(5) Determination of sintering yield rate: For each example, 50 samples without visual defects after debinding were collected, sintered, and the yield rate was calculated. Specifically, if cracks, deformation, or breakage occurred, it was considered unqualified.

The specific test data are as follows:

The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.

Claims (6)

1. A method for preparing a lithium disilicate glass ceramic bracket, characterized in that it comprises the following steps: (1) lithium disilicate glass ceramic powder, acrylate, polyethylene glycol, and light-curable resin are uniformly mixed in a ratio of 8:0.08:0.4:1.2 to obtain a slurry; (2) curing the slurry by photocuring printing to obtain a dental bracket blank; (3) debinding and sintering the bracket blank to obtain a finished lithium disilicate glass ceramic bracket; The preparation method of the lithium disilicate glass ceramic powder is: 1) dispersing a silicon source reagent and a lithium source reagent in a dispersant at a silicon-to-lithium molar ratio of 1:1 to obtain a precursor solution; 2) adding an initiator to the precursor solution to convert the precursor solution into a gel solution; 3) drying and grinding the gel solution to obtain a precursor powder; 4) heat treating the precursor powder at 600-1000° C. for 0.5-10 h, and grinding the precursor powder to a particle size of ≤200 mesh after cooling to obtain a finished lithium disilicate glass ceramic powder; The acrylic acid ester is lauryl acrylate, and the molecular weight of the polyethylene glycol is 1000 g/mol. 2. The method for preparing a lithium disilicate glass-ceramic bracket according to claim 1, characterized in that the silicon source reagent is selected from one or more of tetraethyl orthosilicate, silicate, silica sol, and hexamethyldisiloxane; and the lithium source reagent is selected from alkyl lithium and/or alcohol lithium. 3. The method for preparing a lithium disilicate glass ceramic bracket according to claim 1, characterized in that the initiator is selected from one or more of water, polyvinyl alcohol, a water-ethanol mixture, a water-acetone mixture, a water-isopropanol mixture, and polyethylene glycol; The amount of the initiator used is 0.1-10% of the volume of the precursor solution. 4. The method for preparing a lithium disilicate glass ceramic bracket according to claim 1, characterized in that in step 1), a silicon source reagent and a lithium source reagent are dispersed in a dispersant, and stirred at a stirring speed of 100 to 1000 rpm for 12 to 36 hours to obtain a precursor solution; Wherein, the dispersant is water and/or ethanol. 5. The method for preparing a lithium disilicate glass ceramic bracket according to claim 1, wherein step (3) comprises: (3.1) debinding the dental bracket blank; wherein the temperature curve used for debinding is: heating to 400-800°C at a heating rate of 0.1-10°C/min, and maintaining the temperature at 400-800°C for 0.5-10h; (3.2) Sintering the dental bracket blank after debinding; wherein the temperature curve adopted for sintering is: heating to 800~1250℃ at a heating rate of 0.5~20℃/min, and keeping the temperature at 800~1250℃ for 0.5~10h. 6. A lithium disilicate glass ceramic bracket, characterized in that it is prepared by the preparation method of a lithium disilicate glass ceramic bracket according to any one of claims 1 to 5.