High-strength and high-permeability lithium disilicate glass ceramic and preparation method and application thereof
阅读说明：本技术 一种高强度和高透性二硅酸锂玻璃陶瓷及其制备方法和应用 (High-strength and high-permeability lithium disilicate glass ceramic and preparation method and application thereof ) 是由 张佳新 聂全义 赵丽佳 周生刚 虞勇 王晓俊 于 2021-08-06 设计创作，主要内容包括：本发明提供了一种高强度和高透性二硅酸锂玻璃陶瓷及其制备方法和应用,本发明通过优化原料配比、调控热处理条件制备得到以二硅酸锂为主晶相,以偏硅酸锂、磷酸锂或石英为杂相的二硅酸锂玻璃陶瓷,其中二硅酸锂晶体的尺寸大于700nm,长径比不少于3；所述二硅酸锂玻璃陶瓷的三点弯曲强度为450～750MPa,断裂韧性高于3.5MPa·m～(1/2),1mm厚样品在550nm处的光学透过率在10％～80％内可调节；所述二硅酸锂玻璃陶瓷兼具了高强度和高透性的优良性能,有效地降低了修复体崩缺的风险,较好地模拟了自然牙齿的坚韧和透光性,具有较好的应用前景。(The invention provides a high-strength and high-permeability lithium disilicate glass ceramic and a preparation method and application thereofLithium, lithium phosphate or quartz is hetero-phase lithium disilicate glass ceramic, wherein the size of lithium disilicate crystal is more than 700nm, and the length-diameter ratio is not less than 3; the three-point bending strength of the lithium disilicate glass ceramic is 450-750 MPa, and the fracture toughness is higher than 3.5 MPa.m 1/2 The optical transmittance of a sample with the thickness of 1mm at 550nm is adjustable within 10-80%; the lithium disilicate glass ceramic has the excellent performances of high strength and high permeability, effectively reduces the risk of prosthesis collapse, better simulates the toughness and light transmittance of natural teeth, and has better application prospect.)
1. A high-strength and high-permeability lithium disilicate glass ceramic, which is characterized by comprising the following raw material components: SiO 22 63～75wt％、Li2O 13～18wt％、Al2O3 1～6wt％、K2O 1～10wt％、P2O52-6 wt%, 0-4 wt% of additive and 0-10 wt% of colorant;
the main crystal phase of the lithium disilicate glass ceramic is lithium disilicate crystal, and the impurity phase is any one or the combination of at least two of lithium metasilicate, lithium phosphate and quartz; the size of the lithium disilicate crystal is more than 700nm, and the length-diameter ratio is not less than 3.
2. The lithium disilicate glass-ceramic according to claim 1, having a raw material composition comprising: SiO 22 65～70wt％、Li2O 14～16wt％、Al2O3 2～5wt％、K2O 2～8wt％、P2O53-5 wt%, 1-3 wt% of additive and 2-5 wt% of colorant;
preferably, the raw material composition of the lithium disilicate glass ceramic further comprises 0-6 wt% of CaO, 0-5 wt% of BaO, and B2O30～10wt％、ZrO2Or HfO20 to 10 wt% of any one or a combination of at least two of them, but none of them contains 0.
3. The lithium disilicate glass-ceramic according to claim 1 or 2, wherein the additive comprises a monovalent metal oxide and a divalent metal oxide;
preferably, the monovalent metal oxide comprises Na2O、Rb2O or Cs2Any one or a combination of at least two of O;
preferably, the divalent metal oxide comprises any one of MgO, SrO or ZnO, or a combination of at least two thereof.
4. The lithium disilicate glass-ceramic of any one of claims 1 to 3, wherein the colorant comprises Fe2O3、TiO2、CeO2、CuO、Cr2O3、MnO、SeO2、V2O5、In2O3Or a combination of any one or at least two of rare earth oxides;
preferably, the rare earth oxide comprises La2O3、Nd2O3、Tb2O3、Pr6O11Or Er2O3Any one or a combination of at least two of them.
5. The lithium disilicate glass-ceramic according to any one of claims 1 to 4, wherein the lithium disilicate crystals are in the form of shuttles;
preferably, the lithium disilicate crystals have a microstructure of three-dimensional interlacing and grain interlocking.
6. The lithium disilicate glass ceramic according to any one of claims 1 to 5, wherein when the lithium disilicate crystal has a size of more than 700nm and less than 1200nm and an aspect ratio of 3 to 5, a 1mm thick sample of the lithium disilicate glass ceramic has a light transmittance at 550nm of 10% to 40%;
preferably, when the size of the lithium disilicate crystal is larger than or not smaller than 1200nm and the length-diameter ratio is not smaller than 5, the light transmittance of a 1mm thick sample of the lithium disilicate glass ceramic at 550nm is 40-80%.
7. A method for preparing a lithium disilicate glass-ceramic according to any one of claims 1 to 6, comprising the steps of:
(1) mixing the raw materials of the lithium disilicate glass ceramic according to a proportion, and melting after mixing to obtain basic glass liquid;
(2) and (2) sequentially carrying out forming annealing treatment and heat treatment on the basic glass liquid obtained in the step (1) to obtain the lithium disilicate glass ceramic.
8. The method according to claim 7, wherein the mixing in step (1) is performed using a mixer;
preferably, the mixing time in the step (1) is 30-300 min;
preferably, the melting temperature of the step (1) is 1300-1600 ℃;
preferably, the melting time in the step (1) is 1-10 h.
9. The production method according to any one of claims 7 or 8, wherein the step of the shape annealing treatment of step (2) includes: pouring the basic glass liquid into a mold for annealing to obtain base glass;
preferably, the preheating temperature of the die is 200-500 ℃;
preferably, the annealing time is 0.1-24 h;
preferably, the molding annealing treatment is followed by cooling to room temperature;
preferably, the heat treatment comprises at least a first heat treatment and a last heat treatment;
preferably, the heat treatment further comprises an intermediate heat treatment;
preferably, the temperature of the first heat treatment is 500-600 ℃;
preferably, the time of the first heat treatment is 60-240 min;
preferably, the temperature of the intermediate heat treatment is 600-700 ℃;
preferably, the time of the intermediate heat treatment is 30-240 min;
preferably, the temperature of the last heat treatment is 800-860 ℃;
preferably, the time of the last heat treatment is 1-30 min;
preferably, the base glass or the intermediate product before the last heat treatment is subjected to CAD/CAM machining to form the shape of the tooth to be restored;
preferably, the base glass or an intermediate product before the last heat treatment is formed into the shape of the tooth to be restored by a hot press molding method or a lost wax method.
10. Use of a lithium disilicate glass-ceramic according to any one of claims 1 to 6, wherein the lithium disilicate glass-ceramic is used for making dental restorations;
preferably, the dental prosthesis comprises any one of a dental overlay, an inlay, an onlay, an abutment, a single crown, an anterior multi-unit bridge or a posterior multi-unit bridge.
Technical Field
The invention belongs to the technical field of microcrystalline glass, particularly relates to a glass ceramic, and a preparation method and application thereof, and particularly relates to a high-strength and high-permeability lithium disilicate glass ceramic, and a preparation method and application thereof.
Background
The lithium disilicate glass ceramic is microcrystalline glass with homogeneous crystal phase and glass phase distribution and compact structure. The refractive index (1.55) of the lithium disilicate crystal formed by crystallization has good optical matching with the refractive index (1.50) of the glass matrix, so that the lithium disilicate crystal has excellent semi-transparency and can maximally simulate the color and luster and the light transmission characteristics of natural teeth, thereby having excellent aesthetic effect. In addition, the good mechanical properties and the inherent property that the glass matrix is very susceptible to acid etching by HF make it better able to solve the problems of occlusion and adhesion in dental restoration, thus becoming the material of choice for aesthetic restoration of anterior teeth.
Currently, the clinical use of lithium disilicate glass ceramics as dental restorative products is mainly the IPS series of Ivoclar-Vivadent company and the ZLS (zirconia-toughened silicon) series of Dentsply Silona. However, the three-point bending strength is generally between 360 and 440Mpa, so that the jaw teeth are easily cracked or broken due to abrasion or contact with hard food in the actual occlusion process, and great hidden danger and additional economic investment are caused to patients. Much research has been devoted to increasing their strength and improving their reliability and service life.
For example, CN109824351A discloses a high strength ceramic composite for dental restoration, which is prepared by adding ZrSiO to a glass ceramic component4Allowing it to decompose and form ZrO in situ during heat treatment2A microcrystal; due to ZrO2The microcrystal can generate phase transformation from a tetragonal phase to a monoclinic phase in the cooling process to generate volume expansion, so that an extrusion effect is formed on the surrounding lithium disilicate crystal, and the bending strength of the lithium disilicate glass ceramic is improved to 420-479 MPa by using the compressive stress formed by the extrusion effect; US09676656B2 discloses a high strength and beautiful lithium disilicate glass-ceramic containing cristobalite crystals and a preparation method thereof by adding high content of SiO2Preparing glass ceramic with lithium disilicate as main crystal phase and quartz as second phase, and utilizing thermal expansion coefficient of quartz (10.9X 10)-6v/DEG C) is larger than the glass matrix, so that the bending strength of the glass ceramic is improved to 380-440 MPa due to the characteristic of easy formation of compressive stress; CN104108883A discloses a high-strength lithium disilicate glass ceramic and a preparation method thereof, wherein the method is to add high-content MgO and Al into the components2O3Then heat treatment is carried out to make MgO and Al2O3、SiO2Fully reacting to form glass ceramic taking lithium disilicate as a main crystal phase and magnesium aluminum silicate and beta-quartz as impurity phases, and further improving the strength of the glass ceramic to 705MPa through internal compressive stress; however, although the bending strength is improved to a certain extent by the above method, the improved strength is limited, and the refractive index of the introduced second phase (hetero phase) is not matched with that of the glass matrix, which easily causes the problem of reduced light transmittance, so that the method can only be used for repairing the pontic at the posterior tooth position in practical application.
CN108069611A discloses a high-permeability lithium silicate glass ceramics and lithium disilicate glass ceramics, a preparation method and application thereof, wherein the method adjusts SiO in the components2With Li2The mass ratio of O, so as to control the crystal size of lithium disilicate to be less than 200nm, and the crystal size is lower than the range of 380-780 nm of visible light, so that the prepared glass ceramic shows higher light transmittance, but fine crystal size cannot form good tri-crystalThe microstructure of dimensional interweaving and grain interlocking causes the strength to be still maintained at the prior level, namely 360-450 MPa.
In addition, high fracture toughness is also one of the important indicators for evaluating the reliability and the risk of crack or fracture resistance of glass ceramics. IPS series of Ivoclar-Vivadent company has a fracture toughness of 2.0 to 2.5MPa m1/2According to ISO6872, it is known that when the fracture toughness is higher than 3.0MPa · m1/2When in use, the bridge can be effectively used as an anterior three-unit bridge body; when the fracture toughness is higher than 3.5 MPa.m1/2And can be used as a posterior three-unit bridge, which is difficult to meet the requirement of fracture toughness of most of the current glass ceramics.
Therefore, the development of the lithium disilicate glass ceramic with high strength, high permeability and high fracture toughness effectively reduces the risk of prosthesis collapse and better simulates the toughness and light transmittance of natural teeth, and has very important significance in the field of dental restoration.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a high-strength and high-permeability lithium disilicate glass ceramic and a preparation method and application thereof, the lithium disilicate glass ceramic enables the size of the prepared lithium disilicate crystal grains to be controllable by optimizing the composition ratio and regulating and controlling the reaction conditions in the heat treatment process, the three-point bending strength reaches 450-750 MPa, the optical transmittance of a 1mm thick sample at 550nm is adjustable within 10-80%, the risk of prosthesis collapse is effectively reduced, and the toughness and light transmittance of natural teeth are well simulated.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a high strength and high permeability lithium disilicate glass-ceramic having a raw material composition comprising: SiO 2263 to 75 wt%, such as 63 wt%, 65 wt%, 67 wt%, 69 wt%, 71 wt%, 73 wt%, or 75 wt%, etc.; li2O13-18 wt%, such as 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, or 18 wt%; al (Al)2O31 to 6 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%, etc.;K2o1 to 10 wt%, for example, 1 wt%, 3 wt%, 5 wt%, 7 wt%, or 10 wt%; p2O52 to 6 wt%, for example 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%, etc.; 0 to 4 wt% of an additive, such as 0, 1 wt%, 2 wt%, 3 wt%, or 4 wt%; 0 to 10% by weight of a colorant, for example, 0, 2%, 4%, 6%, 8% or 10% by weight, and the above numerical values are not limited to the listed numerical values, and other numerical values not listed in the respective numerical values are also applicable.
The main crystal phase of the lithium disilicate glass ceramic is lithium disilicate crystal, and the hetero-phase is any one or a combination of at least two of lithium metasilicate, lithium phosphate or quartz, and typical but non-limiting examples of the combination are: combinations of lithium metasilicate and lithium phosphate, lithium phosphate and quartz, and the like; the lithium disilicate crystals have a size of more than 700nm, such as 710nm, 800nm, 900nm, 1000nm, 1100nm, 1200nm, 1300nm, or the like; aspect ratios of not less than 3, e.g., 3, 4, 5, or 6, and the above numerical choices are not limited to the recited values, and other non-recited values within the respective numerical ranges are equally applicable.
In the invention, the size of the lithium disilicate crystal is more than 700nm, the length-diameter ratio is not less than 3, and the shape of the lithium disilicate crystal is in a fusiform shape. The "size of lithium disilicate crystal" refers to the length of the long axis of the shuttle crystal, and the aspect ratio refers to the ratio of the length to the width.
In the present invention, the strength, fracture toughness and light transmittance of the lithium disilicate glass ceramic are improved by increasing the size of the lithium disilicate crystals to be close to or larger than the range of the visible maximum wavelength (380nm to 780nm), unlike the prior art which considers that the lithium disilicate glass ceramic has good light transmittance only when the crystal size is smaller than the visible minimum wavelength. This is because the larger the size of the crystal, the smaller the number of crystals in a certain space, and the smaller the grain boundary between the glass matrix and the lithium disilicate crystal, the smaller the scattering effect of the grain boundary on light, and the higher the light transmittance.
The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.
As a preferred technical scheme of the invention, the lithium disilicate glass ceramic comprises the following raw materials: SiO 2265 to 70 wt%, for example 65 wt%, 67 wt%, 69 wt% or 70 wt%, etc.; li2O14-16 wt%, for example 14 wt%, 15 wt% or 16 wt%; al (Al)2O32 to 5 wt%, for example 2 wt%, 3 wt%, 4 wt%, or 5 wt%, etc.; k2O2-8 wt%, for example 2 wt%, 3 wt%, 5 wt%, 7 wt%, or 8 wt%; p2O53 to 5 wt%, for example 3 wt%, 4 wt% or 5 wt%, etc.; 1 to 3 wt% of an additive, for example 1 wt%, 2 wt% or 3 wt%; 2 to 5% by weight, for example 2%, 3%, 4% or 5% by weight, of the colorant, and the above numerical values are not limited to the listed numerical values, and other numerical values not listed in the respective numerical values are also applicable.
Preferably, the raw material composition of the lithium disilicate glass ceramic further comprises 0-6 wt% of CaO, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%; BaO 0 to 5 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%; b is2O30 to 10 wt%, for example, 0.1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, or 10 wt%; ZrO (ZrO)2Or HfO20 to 10 wt%, such as 0.1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, or 10 wt%, and the like, and typical but non-limiting examples of such combinations are: combination of CaO and BaO, CaO, BaO and B2O3Combination of (A) and (B)2O3Or ZrO2Combinations of (a), (b), and the like.
As a preferred embodiment of the present invention, the additive comprises a monovalent metal oxide and a divalent metal oxide.
Preferably, the monovalent metal oxide comprises Na2O、Rb2O or Cs2Any one or a combination of at least two of O, typical but non-limiting examples of which are: na (Na)2O and Rb2Combination of O, Rb2O and Cs2Combination of O, Na2O、Rb2O and Cs2Combinations of O, and the like.
Preferably, the divalent metal oxide comprises any one of, or a combination of at least two of, MgO, SrO or ZnO, typical but non-limiting examples of which are: combinations of MgO and SrO, SrO and ZnO, MgO, SrO and ZnO, and the like.
As a preferred embodiment of the present invention, the colorant comprises Fe2O3、TiO2、CeO2、CuO、Cr2O3、MnO、SeO2、V2O5、In2O3Or rare earth oxides, or combinations of at least two of the foregoing, as typical but non-limiting examples: TiO 22、CeO2And CuO, Fe2O3And TiO2Combination of MnO, SeO2、V2O5And In2O3Combination of (1), V2O5、In2O3And combinations of rare earth oxides, and the like.
Preferably, the rare earth oxide comprises La2O3、Nd2O3、Tb2O3、Pr6O11Or Er2O3Any one or a combination of at least two of the following, typical but non-limiting examples being: la2O3And Nd2O3Combination of (1), Nd2O3、Tb2O3And Pr6O11Combination of (5), Pr6O11And Er2O3Combinations of (a), (b), and the like.
In a preferred embodiment of the present invention, the lithium disilicate crystal is in the form of a shuttle.
Preferably, the lithium disilicate crystals have a microstructure of three-dimensional interlacing and grain interlocking.
In a preferred embodiment of the present invention, when the lithium disilicate crystal has a size of more than 700nm and less than 1200nm and an aspect ratio of 3 to 5, the light transmittance at 550nm of a 1mm thick sample of the lithium disilicate glass ceramic is 10% to 40%, for example, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, but the present invention is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.
Preferably, the lithium disilicate glass ceramic has a light transmittance at 550nm of 40% to 80%, for example, 40%, 45%, 50%, 55%, 60%, 65%, or 70%, or 75% or 80%, for a 1mm thick sample of the lithium disilicate glass ceramic, when the lithium disilicate crystals have a size of not less than 1200nm and an aspect ratio of not less than 5, but not limited to the recited values, and other values not recited in this range of values are also applicable.
In a second aspect, the present invention provides a method for preparing the above lithium disilicate glass ceramic, the method comprising the steps of:
(1) mixing the raw materials of the lithium disilicate glass ceramic according to a proportion, and melting after mixing to obtain basic glass liquid;
(2) and (2) sequentially carrying out forming annealing treatment and heat treatment on the basic glass liquid obtained in the step (1) to obtain the lithium disilicate glass ceramic.
According to the preparation method, all the raw materials are fully melted until bubbles completely escape so as to ensure the quality and color uniformity of a subsequently obtained glass block, then the internal stress of matrix glass is eliminated through forming annealing treatment, the phenomenon that a large amount of internal stress is accumulated in the matrix glass to cause hidden cracking or collapse in the processing process due to overlarge temperature difference is prevented, then the nucleation-growth process of crystal grains is regulated and controlled through heat treatment, lithium disilicate crystals with the size larger than 700nm and the length-diameter ratio not less than 3 are obtained, and the high length-diameter ratio enables the lithium disilicate crystals to form a microstructure with three-dimensional interweaving and crystal grain interlocking, so that the three-point bending strength and the fracture toughness of the glass ceramic are improved.
As a preferable technical scheme of the invention, the mixing in the step (1) is carried out by adopting a mixer.
Preferably, the mixing time in step (1) is 30-300 min, such as 30min, 60min, 90min, 120min, 150min, 180min, 210min, 240min, 270min or 300min, but not limited to the recited values, and other non-recited values in the range of the values are also applicable.
Preferably, the melting temperature in step (1) is 1300-1600 ℃, such as 1300 ℃, 1350 ℃, 1400 ℃, 1450 ℃, 1500 ℃, 1550 ℃ or 1600 ℃, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the melting time in step (1) is 1 to 10 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
As a preferable embodiment of the present invention, the forming annealing treatment in the step (2) includes: and pouring the basic glass liquid into a mold for annealing to obtain the matrix glass.
Preferably, the preheating temperature of the mold is 200 to 500 ℃, for example, 200 ℃, 300 ℃, 400 ℃ or 500 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the annealing time is 0.1 to 24 hours, such as 0.1 hour, 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, or 24 hours, but not limited to the recited values, and other values not recited within the range of values are also applicable.
Preferably, the forming annealing treatment is followed by cooling to room temperature.
Preferably, the heat treatment includes at least a first heat treatment and a last heat treatment.
Preferably, the heat treatment further comprises an intermediate heat treatment.
In the present invention, when the number of heat treatments is 3, the heat treatments are performed in the order of "first time", "intermediate time", and "last time".
Preferably, the temperature of the first heat treatment is 500 to 600 ℃, for example, 500 ℃, 520 ℃, 540 ℃, 560 ℃, 580 ℃, or 600 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the time of the first heat treatment is 60 to 240min, such as 60min, 90min, 120min, 150min, 180min, 210min or 240min, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the temperature of the intermediate heat treatment is 600 to 700 ℃, for example 600 ℃, 620 ℃, 640 ℃, 660 ℃, 680 ℃ or 700 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the time of the intermediate heat treatment is 30 to 240min, such as 30min, 60min, 90min, 120min, 150min, 180min, 210min or 240min, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, the temperature of the last heat treatment is 800 to 860 ℃, for example 800 ℃, 810 ℃, 820 ℃, 830 ℃, 840 ℃, 850 ℃ or 860 ℃, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the time of the last heat treatment is 1-30 min, such as 1min, 5min, 10min, 15min, 20min, 25min or 30min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
In the invention, the first heat treatment of the matrix glass can form a large number of crystal nuclei in the glass matrix; after the intermediate heat treatment, the glass ceramic with lithium metasilicate as the main crystal phase can be formed; the final heat treatment results in the formation of a glass-ceramic having lithium disilicate as the main crystal phase, and therefore the temperature and time for each heat treatment is important. If the temperature of the first heat treatment is too low, the glass matrix is difficult to nucleate or the nucleation amount is less, and the uniform growth of lithium metasilicate crystals in the middle heat treatment process cannot be effectively controlled; if the temperature of the first heat treatment is too high, a large number of crystal nuclei grow to form lithium metasilicate crystals, which is not beneficial to controlling the size of the lithium disilicate crystals; if the temperature of the intermediate heat treatment is too low, a large amount of crystal nuclei are difficult to grow to form lithium metasilicate crystals which are easy to process, so that the processing performance is poor; if the temperature of the intermediate heat treatment is too high, lithium metasilicate crystals are easily converted into lithium disilicate crystals that are difficult to process, resulting in a decrease in processability; if the temperature of the last heat treatment is too low, lithium disilicate crystals with higher length-diameter ratio are difficult to form, and the strength value is lower; if the temperature of the last heat treatment is too high, abnormal growth of lithium disilicate crystals may be caused, resulting in a decrease in strength and light transmittance.
Preferably, the base glass or the intermediate product before the last heat treatment is subjected to CAD/CAM machining to form the shape of the tooth to be restored.
Preferably, the base glass or an intermediate product before the last heat treatment is formed into the shape of the tooth to be restored by a hot press molding method or a lost wax method.
As a preferred technical scheme of the invention, the preparation method comprises the following steps:
(1) the method comprises the following steps of (1) proportionally loading raw materials of lithium disilicate glass ceramics into a mixer, mixing for 30-300 min, melting for 1-10 h at 1300-1600 ℃ after mixing, and obtaining basic glass liquid after components are uniformly distributed and bubbles are completely escaped;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 200-500 ℃ for annealing for 0.1-24 h, and naturally cooling to room temperature to obtain base glass;
heating the substrate glass to 500-600 ℃, and keeping the temperature for 60-240 min; then heating to 600-700 ℃, and preserving heat for 30-240 min; then, processing the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical processing, hot press molding or a lost wax method, and then grinding and polishing the surface; and finally, putting the processed sample into a high-temperature electric furnace, and preserving the heat for 1-30 min at the temperature of 800-860 ℃ to obtain the lithium disilicate glass ceramic taking the lithium disilicate crystal as the main crystal phase.
In a third aspect, the present invention provides the use of a lithium disilicate glass ceramic as described above for the manufacture of a dental restoration.
Preferably, the dental prosthesis comprises any one of a dental overlay, an inlay, an onlay, an abutment, a single crown, an anterior multi-unit bridge or a posterior multi-unit bridge.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the lithium disilicate glass ceramic, the size of lithium disilicate crystals is increased, so that a microstructure with three-dimensional interweaving and grain interlocking can be well formed, the three-point bending strength of the lithium disilicate glass ceramic is maintained between 450 and 750MPa, and the fracture toughness is higher than 3.5 MPa.m1/2(ii) a On the other hand, the increase of the size of the crystal can weaken the scattering effect of a crystal boundary on light, so that the optical transmittance of a sample with the thickness of 1mm at the position of 550nm can be adjusted within 10-80%, the excellent performances of high strength, high permeability and high fracture toughness are really achieved, the risk of collapse is effectively reduced, and the toughness and light transmittance of natural teeth are better simulated;
(2) the preparation method provided by the invention has the advantages that the crystal size is regulated and controlled by optimizing the formula composition and controlling the conditions in the heat treatment process, the process flow is simple, the economic benefit is high, and the industrial application prospect is good.
Drawings
FIG. 1 is a Differential Scanning Calorimetry (DSC) plot of a lithium disilicate glass ceramic provided in example 1 of the present invention;
FIG. 2 is a microscopic morphology of a lithium disilicate glass ceramic provided in example 1 of the present invention;
FIG. 3 is a graph showing the distribution of the length dimension of lithium disilicate crystals in the lithium disilicate glass ceramic provided in example 1 of the present invention;
FIG. 4 is a graph showing the distribution of the width dimension of lithium disilicate crystals in the lithium disilicate glass ceramic provided in example 1 of the present invention;
FIG. 5 is an X-ray diffraction pattern (XRD) of a lithium disilicate glass ceramic provided in example 1 of the present invention;
FIG. 6 is a graph showing the transmittance of the lithium disilicate glass ceramic provided in example 1 of the present invention in the visible light range of 400 to 900 nm.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.
The following are typical but non-limiting examples of the invention:
the raw material compositions of lithium disilicate glass ceramics prepared in the following examples and comparative examples are shown in table 1, in which the contents of the respective components are mass percentages.
TABLE 1
Example 1
Example 2
Example 3
Example 4
Example 5
Example 6
SiO2
67.5
69
70
64.5
72
70
Li2O
14.7
16.7
13.4
15.5
13
14
K2O
4.2
3.2
6.1
5.7
3
3.4
Al2O3
3.7
3.3
4.8
5.0
4
3.5
P2O5
3.3
4.2
2.9
4.4
5
4.8
Rb2O
0.3
0.6
0.5
1.2
0.8
1.0
MgO
1.0
0.4
0.6
0.5
—
—
CaO
0.4
—
0.3
—
—
0.2
Fe2O3
1.75
1.2
0.4
0.8
1.6
1.2
Tb2O3
2.7
0.3
0.8
1.0
0.4
1.9
La2O3
0.45
0.3
0.2
0.4
0.2
—
ZnO2
—
0.8
—
1.0
—
—
Example 1:
the embodiment provides a preparation method of a high-strength and high-permeability lithium disilicate glass ceramic, which comprises the following steps:
(1) the raw materials of the lithium disilicate glass ceramic are proportionally loaded into a mixer, mixed for 40min, placed in a platinum crucible after being mixed, melted for 5h at 1450 ℃, and after the components are uniformly distributed and bubbles are completely escaped, the basic glass liquid is obtained;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 420 ℃ for annealing for 10 hours, and then naturally cooling to room temperature to obtain base glass;
heating the matrix glass to 520 ℃, preserving the heat for 130min, and naturally cooling to room temperature; then heating to 660 ℃, preserving the heat for 150min, and naturally cooling to room temperature; then, machining the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical machining, and then grinding and polishing the surface; finally, putting the processed sample into a high-temperature electric furnace, and preserving heat for 2min at 840 ℃ to obtain Li2Si2O5Crystal as main crystal phase, with Li2SiO3And Li3PO4Lithium disilicate glass ceramics which are heterogeneous.
The lithium disilicate glass ceramic obtained as described above is characterized in that a DSC diagram is shown in FIG. 1, a micro-topography diagram is shown in FIG. 2, a length size distribution diagram of lithium disilicate crystals is shown in FIG. 3, a width size distribution diagram of lithium disilicate crystals is shown in FIG. 4, an XRD diagram of lithium disilicate glass ceramic is shown in FIG. 5, and a transmittance curve of the lithium disilicate glass ceramic in visible light in a range of 400nm to 900nm is shown in FIG. 6.
As can be seen from FIG. 1, the glass transition temperature T of the sampleg485 c, which means that the formation of a large number of crystal nuclei in the glass matrix can be effectively promoted only when the heat treatment temperature is higher than 485 c. 628 ℃ is the exothermic peak when lithium metasilicate crystals are formed, 802 ℃ is the exothermic peak when lithium disilicate crystals are formed, and 959 ℃ is the softening point of the glass ceramic, which indicates that the sample is easy to soften and deform above the temperature.
As can be seen from fig. 2, the microstructure of the sample is spindle-shaped and is distributed by a mechanism of three-dimensional interlacing and grain interlocking, and further from table 3, it can be found that the spindle-shaped lithium disilicate crystal has a size of 1080nm and an aspect ratio of 4.7, and the high aspect ratio facilitates inter-grain interlacing, so that the three-point bending of the glass ceramic is effectively increased to 580 MPa. In addition, the lithium disilicate glass ceramic has a fracture mode along the crystal fracture, and the high long-diameter ratio can effectively prolong the crack propagation path, thereby dissipating the driving force of crack propagation and effectively improving the fracture toughness of the lithium disilicate glass ceramic to 3.62 MPa.m1/2And meets the use requirement of the national standard ISO6872 on the posterior three-unit bridge body.
As can be seen from FIGS. 3 and 4, the lithium disilicate crystals had an average length of 1.08 μm and an average width of 0.23. mu.m.
As can be seen from FIG. 5, the main crystal phase of the sample was lithium disilicate (Li)2Si2O5) The hetero-phase is lithium metasilicate (Li)2SiO3) And lithium phosphate (Li)3PO4)。
As can be seen from FIG. 6, the optical transmittance at 550nm of the 1mm thick lithium disilicate glass ceramic sample is 20.11%, which well meets the clinical requirement of high transmittance of the dental restorative material (the optical transmittance at 550nm of the 1mm thick sample is 20-55%).
Example 2:
the embodiment provides a preparation method of a high-strength and high-permeability lithium disilicate glass ceramic, which comprises the following steps:
(1) the raw materials of the lithium disilicate glass ceramic are proportionally loaded into a mixer, mixed for 30min, placed in a platinum crucible after being mixed, melted for 3h at 1450 ℃, and after the components are uniformly distributed and bubbles are completely escaped, the basic glass liquid is obtained;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 400 ℃ for annealing for 3h, and then naturally cooling to room temperature to obtain base glass;
heating the substrate glass to 550 ℃, preserving the heat for 100min, and naturally cooling to room temperature; then heating to 660 ℃, preserving the temperature for 180min, and naturally cooling to room temperature; then, machining the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical machining, and then grinding and polishing the surface; finally, putting the processed sample into a high-temperature electric furnace, and preserving the heat for 6min at 840 ℃ to obtain Li2Si2O5Crystal as main crystal phase, with Li2SiO3Lithium disilicate glass ceramics which are heterogeneous.
Example 3:
the embodiment provides a preparation method of a high-strength and high-permeability lithium disilicate glass ceramic, which comprises the following steps:
(1) the raw materials of the lithium disilicate glass ceramic are proportionally loaded into a mixer, mixed for 60min, placed in a platinum crucible after being mixed, melted for 5h at 1450 ℃, and after the components are uniformly distributed and bubbles are completely escaped, the basic glass liquid is obtained;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 450 ℃ for annealing for 2h, and then naturally cooling to room temperature to obtain matrix glass;
heating the matrix glass to 570 ℃, preserving heat for 140min, and naturally cooling to room temperature; then heating to 670 ℃, preserving the heat for 210min, and naturally cooling to room temperature; then, machining the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical machining, and then grinding and polishing the surface; finally, will processPutting the good sample into a high-temperature electric furnace, and preserving the heat for 10min at the temperature of 830 ℃ to obtain Li2Si2O5Crystal as main crystal phase, with Li2SiO3Lithium disilicate glass ceramics which are heterogeneous.
Example 4:
the embodiment provides a preparation method of a high-strength and high-permeability lithium disilicate glass ceramic, which comprises the following steps:
(1) the method comprises the following steps of (1) proportionally loading raw materials of lithium disilicate glass ceramics into a mixer, mixing for 100min, placing the mixture into a platinum crucible, melting for 3h at 1600 ℃, and obtaining basic glass liquid after components are uniformly distributed and bubbles are completely escaped;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 450 ℃ for annealing for 4h, and then naturally cooling to room temperature to obtain matrix glass;
heating the substrate glass to 530 ℃, preserving the heat for 120min, and naturally cooling to room temperature; then heating to 630 ℃, preserving heat for 130min, and naturally cooling to room temperature; then, machining the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical machining, and then grinding and polishing the surface; finally, putting the processed sample into a high-temperature electric furnace, and preserving the heat for 3min at 860 ℃ to obtain Li2Si2O5Crystal as main crystal phase, with Li2SiO3And Li3PO4Lithium disilicate glass ceramics which are heterogeneous.
Example 5:
the embodiment provides a preparation method of a high-strength and high-permeability lithium disilicate glass ceramic, which comprises the following steps:
(1) the method comprises the following steps of (1) proportionally loading raw materials of lithium disilicate glass ceramics into a mixer, mixing for 300min, placing the mixture into a platinum crucible, melting for 10h at 1300 ℃, and obtaining basic glass liquid after components are uniformly distributed and bubbles are completely escaped;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 200 ℃ for annealing for 24 hours, and then naturally cooling to room temperature to obtain base glass;
heating the matrix glass to 600 ℃, preserving the heat for 60min, and naturally cooling to room temperature; then heating to 700 ℃, preserving the heat for 30min, and naturally cooling to room temperature; then, machining the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical machining, and then grinding and polishing the surface; finally, putting the processed sample into a high-temperature electric furnace, and preserving heat for 1min at 850 ℃ to obtain Li2Si2O5Crystal as main crystal phase, with Li2SiO3Lithium disilicate glass ceramics which are heterogeneous.
Example 6:
the embodiment provides a preparation method of a high-strength and high-permeability lithium disilicate glass ceramic, which comprises the following steps:
(1) the method comprises the following steps of (1) proportionally loading raw materials of lithium disilicate glass ceramics into a mixer, mixing for 200min, placing the mixture into a platinum crucible, melting for 1h at 1500 ℃, and obtaining basic glass liquid after components are uniformly distributed and bubbles are completely escaped;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 500 ℃ for annealing for 0.1h, and then naturally cooling to room temperature to obtain base glass;
heating the substrate glass to 500 ℃, preserving the heat for 240min, and naturally cooling to room temperature; then heating to 600 ℃, preserving the heat for 240min, and naturally cooling to room temperature; then, machining the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical machining, and then grinding and polishing the surface; finally, putting the processed sample into a high-temperature electric furnace, and preserving the heat for 30min at the temperature of 800 ℃ to obtain Li2Si2O5Crystal as main crystal phase, with Li2SiO3And Li3PO4Lithium disilicate glass ceramics which are heterogeneous.
Example 7:
this example provides a method for preparing a high strength and high permeability lithium disilicate glass ceramic using the same raw materials as in example 1, comprising the steps of:
(1) the raw materials of the lithium disilicate glass ceramic are proportionally loaded into a mixer, mixed for 100min, placed in a platinum crucible after being mixed, melted for 4h at 1400 ℃, and after the components are uniformly distributed and bubbles are completely escaped, the basic glass liquid is obtained;
(2) pouring the basic glass liquid obtained in the step (1) into a mold at 450 ℃ for annealing for 5 hours, and then naturally cooling to room temperature to obtain matrix glass;
heating the substrate glass to 550 ℃, preserving heat for 240min, and naturally cooling to room temperature; then, machining the obtained intermediate product into the shape of the tooth to be restored by adopting CAD/CAM mechanical machining, and then grinding and polishing the surface; finally, putting the processed sample into a high-temperature electric furnace, and preserving the heat for 30min at the temperature of 810 ℃ to obtain Li2Si2O5Lithium disilicate glass ceramics with crystal as main crystal phase and lithium metasilicate and quartz as impurity phase.
Example 8:
this example provides a method for producing a high strength and high permeability lithium disilicate glass ceramic using the same raw materials as in example 1, with reference to the production method in example 1, except that: the temperature of the first heat treatment of the base glass in the step (2) is 450 ℃.
Example 9:
this example provides a method for producing a high strength and high permeability lithium disilicate glass ceramic using the same raw materials as in example 3, with reference to the production method in example 3, except that: the temperature of the first heat treatment of the base glass in the step (2) is 630 ℃.
Comparative example 1:
this comparative example provides a method of preparing a lithium disilicate glass ceramic using the same raw materials as those used in example 1, with reference to the preparation method in example 1, except that: heating the matrix glass to 670 ℃ in the step (2), preserving the heat for 180min, and naturally cooling to room temperature; then, the CAD/CAM mechanical processing is adopted to process the obtained intermediate product into the shape of the tooth to be restored, and then the surface is polished and polishedA light; finally, putting the processed sample into a high-temperature electric furnace, and preserving the heat for 5min at 840 ℃ to obtain Li2Si2O5Crystal as main crystal phase, with Li2SiO3Lithium disilicate glass ceramics which are heterogeneous.
First, the base glasses obtained in the manufacturing processes of examples 1 to 9 and comparative example 1 and the intermediate products in the heat treatment process were subjected to the corresponding phase analyses, and the results are shown in Table 2.
TABLE 2
Wherein, TgIs the glass transition temperature; t isNAnd tNRespectively the first heat treatment temperature and time; t isP1And tP1Respectively the intermediate heat treatment temperature and time; t isP2And tP2The temperature and time of the last heat treatment are respectively.
Next, the lithium disilicate glass ceramics prepared in examples 1 to 9 and comparative example 1 were measured for crystal size, aspect ratio, light transmittance at 550nm, three-point bending strength, hardness, fracture toughness and chemical solubility, and the respective test method conditions were as follows, and the measurement results are shown in Table 3.
Crystal size was measured and counted using Nano Measurer 1.2 software.
Light transmittance: and testing the test sample in a wavelength range of 400-900 nm by using a spectrophotometer, wherein the thickness of the test sample is 1 mm.
③ mechanical property: the three-point bending strength and fracture toughness characterization of the invention adopts ISO6872:2008 international standard. For the test of the three-point bending strength, 15 samples are tested, and the average value of the obtained three-point bending strength values is calculated; for the fracture toughness test, 10 specimens were tested by the V-groove beam method (SEVNB) to obtain an average value of fracture toughness of the specimens.
The hardness test of the invention adopts ISO14705:2008 international standard, and uses Vickers hardness tester, the applied load is 1 kilogram force (1kgf), the test is 15 times, and the average value of the Vickers hardness of the sample is obtained.
Chemical solubility: the chemical solubility of the invention is tested and analyzed according to ISO6872:2008 international standard.
TABLE 3
In examples 1 to 6, by adopting the preparation method of the present invention, the light transmittance of the obtained lithium disilicate glass ceramic at a wavelength of 550nm is 20.11 to 53.08% by optimizing the raw material components and regulating and controlling the conditions of each heat treatment, and the requirement of high light transmittance for the dental restorative material in clinical practice is usually maintained between 20 to 55% (550nm wavelength), which indicates that the requirement of high light transmittance for the dental restorative material in clinical practice is completely met. The obtained lithium disilicate glass ceramic has good processability, and can remarkably reduce the problems of breakage, large abrasion to a machine needle and the like in the mechanical processing process. In addition, the lithium disilicate crystal has a size larger than 1080nm and a length-diameter ratio larger than 4.7, so that a microstructure of three-dimensional interweaving and grain interlocking can be well formed, the three-point bending strength of the glass ceramic is maintained at 580-750 MPa, and the risk of tooth collapse is effectively reduced. The obtained lithium disilicate glass ceramic has a fracture toughness of 3.58 to 5.56MPa · m1/2A hardness of 5.65 to 6.32GPa and a chemical solubility of 29.3 to 43.6 [ mu ] g/cm2Meets the clinical requirements on dental materials.
Example 7 by using the preparation method of the present invention, the light transmittance of the obtained lithium disilicate glass ceramic at the wavelength of 550nm can still reach 26.5% by only two heat treatments,and has good processability, and simultaneously, the three-point bending strength reaches 560MPa, and the fracture toughness reaches 4.02 MPa.m1/2The hardness reaches 5.85GPa, and the chemical solubility is 44.0 mu g/cm2Meets the clinical requirements on dental materials.
In the preparation process of the embodiment 8, the temperature during the first heat treatment is reduced, and the uniform growth of crystals in the heat treatment process cannot be effectively controlled, so that the light transmittance of the finally obtained lithium disilicate glass ceramic at the wavelength of 550nm is reduced, and the three-point bending strength is reduced; example 9 increasing the temperature at the first heat treatment during the preparation is disadvantageous for the control of the lithium disilicate crystal size, and also results in a decrease in the light transmittance at a wavelength of 550nm and a decrease in the three-point bending strength of the resulting lithium disilicate glass ceramic.
The lithium disilicate glass ceramic prepared in the comparative example 1 has a low aspect ratio, so that a microstructure of three-dimensional interlacing and grain interlocking cannot be formed, the light transmittance of the obtained lithium disilicate glass ceramic at the wavelength of 550nm is low, and the three-point bending strength is seriously reduced.
It can be seen from the above examples and comparative examples that the lithium disilicate glass ceramic of the present invention can form a microstructure of three-dimensional interlacing and grain interlocking by increasing the size of lithium disilicate crystals, so that the three-point bending strength of the lithium disilicate glass ceramic is maintained between 450-750 MPa, and the fracture toughness is higher than 3.5 MPa.m1/2(ii) a On the other hand, the increase of the size of the crystal can weaken the scattering effect of a crystal boundary on light, so that the optical transmittance of a sample with the thickness of 1mm at the position of 550nm can be adjusted within 10-80%, the excellent performances of high strength, high permeability and high fracture toughness are really achieved, the risk of collapse is effectively reduced, and the toughness and light transmittance of natural teeth are better simulated; the preparation method regulates and controls the crystal size by optimizing the formula composition and controlling the conditions in the heat treatment process, has simple process flow and high economic benefit, and has better industrial application prospect.
The applicant states that the present invention is illustrated by the above examples to show the products and detailed methods of the present invention, but the present invention is not limited to the above products and detailed methods, i.e. it is not meant that the present invention must rely on the above products and detailed methods to be carried out. It will be apparent to those skilled in the art that any modifications to the present invention, equivalents thereof, additions of additional operations, selection of specific ways, etc., are within the scope and disclosure of the present invention.