Dental glass-ceramic restorations and methods of making the same

Abstract

The application discloses a dental glass ceramic restoration and a preparation method thereof, and belongs to the technical field of dental restorations. The technical scheme comprises the following steps: a restoration wax pattern is prepared by using a digital design method; the restoration wax pattern is embedded with plaster material to perform mold turning to form a plaster mold, the plaster mold has an outwardly protruding grouting opening; the mold cavity of the plaster mold is filled with glass slurry, and the grouting opening is always filled with the glass slurry to the glass slurry in the mold cavity of the plaster mold to dry to form a hardened body; the hardened body is taken out to perform glue removal, and then crystallization sintering is performed; the glass slurry comprises glass powder, and the particle size of the glass powder is selected from any value in the range of 3-5 mu m. The application is applied to the aspect of dental restoration, solves the problem that the preparation process of the existing dental glass ceramic restoration is complex, and has the characteristics of a simple process.

Description

Technical Field

[0001] This invention belongs to the field of dental prosthesis technology, and particularly relates to a dental glass-ceramic prosthesis and its preparation method. Background Technology

[0002] Currently, the two main methods for molding dental restorations are fusion molding and sintering, but both methods have the problem of complex processes. Fusion molding requires first molding a glass block, but the glass block is brittle and prone to cracking, and is also prone to crystallization problems. Sintering, on the other hand, is difficult to mold by dry pressing, and can easily result in edge chipping. Furthermore, both methods require complex processes to create a ceramic block before it is machined or hot-pressed into shape.

[0003] Chinese patent CN109069238A discloses a method for preparing dental prostheses, in which a blank is provided, the blank being made of ceramic, particularly glass ceramic or glass, and the blank having a predefined spatial dependence of color and / or opacity in its volume, and the blank is pressed into a pressure chamber of a pressure muffle furnace, the material of the blank being pressed into a mold cavity corresponding to the dental prosthesis through a channel structure emanating from the pressure chamber, wherein the channel structure and the spatial dependence of color and / or opacity in the blank are coordinated to obtain one of a variety of possible color and / or opacity distributions in the ceramic material of the dental prosthesis formed in the mold cavity.

[0004] The aforementioned patents also require the preparation of blanks first, and then the blanks are processed to obtain dental restorations, which still presents the problem of complex processes. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to overcome the problem of the complexity of the existing dental glass-ceramic restoration preparation process, and to propose a dental glass-ceramic restoration with a simple process and its preparation method.

[0006] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing a dental glass-ceramic restoration, comprising: Using digital design methods to create wax models of restorations; A plaster mold is formed by embedding a wax pattern of the restoration with plaster material and then casting it. The plaster mold has an outward-protruding grout injection port. The cavity of the plaster mold is filled with glass slurry, and the slurry outlet is kept filled with glass slurry until the glass slurry in the cavity of the plaster mold dries and forms a hardened blank. Remove the hardened blank and remove the binder; after removing the binder, crystallize and sinter. The glass slurry includes glass powder, the particle size of which is selected from any value between 3 and 5 μm.

[0007] Preferably, the wax pattern of the restoration is enlarged by 20-25% proportionally to the restoration.

[0008] Preferably, by mass percentage, the glass powder comprises 60-75% SiO2, 10-25% Li2O, 0-5% ZnO, 0.1-10% Al2O3, 0.1-8% K2O, 0-10% P2O5, and 0-10% ZrO2.

[0009] Preferably, the glass slurry includes a slurry, and the mass ratio of glass powder to slurry is 6-8:2-4.

[0010] Preferably, the slurry comprises 95-99% water, 0.5-3.5% dispersant and 0.5-2% low-carbon alcohol by mass percentage.

[0011] Preferably, the dispersant is polyethylene glycol and / or polyvinyl alcohol, and the lower alcohol is ethanol and / or methanol.

[0012] Preferably, by mass percentage, the glass powder comprises 65-73% SiO2, 12-20% Li2O, 2-4% ZnO, 3-8% Al2O3, 3-6% K2O, 3-8% P2O5, and 1-5% ZrO2; the slurry comprises 96-98% water, 1.5-3% dispersant, and 1-1.5% low-carbon alcohol.

[0013] Preferably, the debinding process includes: debinding at 300-500℃ for 1-3 hours; the crystallization sintering conditions include: sintering at 750-900℃ under vacuum conditions, heating rate of 15-30℃ / min, and holding time of 0.5-1.5 hours.

[0014] Preferably, after crystallization and sintering, an intermediate repair body is obtained. The surface of the intermediate repair body is then polished and glazed to obtain the final repair body.

[0015] In another aspect, the present invention provides a dental glass-ceramic restoration according to the above-mentioned technical solution, wherein the main crystalline phase of the restoration is lithium disilicate.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing dental glass-ceramic restorations. The method utilizes digital design to create a mold cavity, performs glass-ceramic slurry injection molding, and then directly crystallizes and sintersects the material after drying to obtain the final restoration. The process is simple, cost-effective, and helps reduce the difficulty of product manufacturing. Attached Figure Description

[0017] Figure 1This is a schematic diagram of the preparation process of the dental glass-ceramic restoration provided by the present invention; Figure 2 This is a flowchart illustrating the preparation process of the dental glass-ceramic restoration provided by the present invention. Figure 3 The image shown is the XRD pattern of the crystal phase of the repair body provided in Example 1 of this invention. In the above figures, 1 is the plaster mold; 2 is the mold cavity; and 3 is the grout injection port. Detailed Implementation

[0018] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0019] A method for preparing dental glass-ceramic restorations, such as Figure 1 , 2 As shown, this includes: creating wax models of the restoration using digital design methods. These digital design methods can be CAD, CAM, or 3D printing.

[0020] A method for preparing a dental glass-ceramic restoration includes: embedding a restoration wax pattern in plaster material to form a plaster mold 1, wherein the plaster mold 1 has an outwardly protruding injection port 3. The plaster mold 1 may be a two-part structure to facilitate the removal of the dried blank. The inner surface of the plaster mold 1 forms a cavity 2 corresponding to the restoration wax pattern.

[0021] A method for preparing a dental glass-ceramic restoration includes: filling a cavity 2 of a plaster mold 1 with glass slurry, and maintaining a continuous flow of glass slurry in the injection port 3 until the glass slurry in the cavity 2 of the plaster mold 1 dries to form a hardened preform. The glass slurry is in suspension form. When injected into the cavity 2 of the plaster mold 1, the plaster absorbs the moisture from the glass slurry, allowing it to dry quickly. Maintaining a continuous flow of glass slurry in the injection port 3 before drying effectively prevents structural defects caused by moisture loss. It should be noted that dental glass-ceramic restorations are generally small in size and can dry and solidify quickly under the action of plaster.

[0022] The above technical solution specifies that the plaster mold 1 has an outwardly protruding grouting port 3, and the grouting port 3 is left with a certain height so that when the volume of the grout shrinks during the drying process, the grouting port 3 can be used to retain the grout for automatic replenishment, and the hardened blank is formed after drying.

[0023] The aforementioned glass slurry includes glass powder, the particle size of which is selected from any value between 3 and 5 μm. By limiting the particle size of the glass powder, the uniformity of the glass powder particle size is ensured, and at the same time, the purpose of uniform shrinkage is achieved.

[0024] A method for preparing dental glass-ceramic restorations includes: removing a hardened preform and removing the adhesive, followed by crystallization and sintering. During drying and sintering, the preform will shrink to a certain extent. Therefore, when making the wax pattern, the subsequent shrinkage must be considered and scaled up to ensure that the final restoration meets the requirements. The magnitude of shrinkage is related to the composition of the glass powder, the particle size of the broken glass powder, the composition of the slurry, and the sintering temperature. This invention has found that, while ensuring the quality of the restoration, the shrinkage rate is between 20% and 25%. Therefore, this invention further requires that the restoration wax pattern be scaled up proportionally by 20%-25% relative to the restoration.

[0025] To ensure the mechanical properties of the restoration, such as flexural strength and fracture toughness, and to control the shrinkage rate of the preform to 20%-25% after drying and sintering, a mold cavity 2, which is proportionally enlarged by 20-25% relative to the restoration, is used to obtain a restoration with structural dimensions that meet the requirements. This invention further specifies the composition of the glass powder, the particle size of the crushed glass powder, the composition of the slurry formulation, and the sintering temperature.

[0026] In a preferred embodiment, the glass powder, by mass percentage, comprises 60-75% SiO2, 10-25% Li2O, 0-5% ZnO, 0.1-10% Al2O3, 0.1-8% K2O, 0-10% P2O5, and 0-10% ZrO2. This glass powder contains the necessary components for forming the lithium silicate crystalline phase, including SiO2, Li2O, nucleating agents, alkali metal oxides, alkaline earth metal oxides, colorants, and fluorescent agents. This technical solution limits the composition of the glass powder because it contains sufficient main components to generate the primary crystalline phase, nucleating agents to control crystallization, stabilizers to ensure the chemical stability of the glass ceramic, fluxes to aid melting, and colorants and fluorescent agents to produce optical effects, thus effectively ensuring the mechanical properties and dimensional stability of the restoration.

[0027] Understandably, the mass percentage of SiO2 can also be any value within the range of 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, etc.; the mass percentage of Li2O can also be any value within the range of 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, etc.; and the mass percentage of ZnO can also be any value within the range of 1%, 2%, 3%, 4%. The mass percentage of Al2O3 can also be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value within that range; the mass percentage of K2O can also be 1%, 2%, 3%, 4%, 5%, 6%, 7%, or any value within that range; the mass percentage of P2O5 can also be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or any value within that range; and the mass percentage of ZrO2 can also be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or any value within that range.

[0028] In a preferred embodiment, the glass slurry comprises a liquid, and the mass ratio of glass powder to liquid is 6-8:2-4. Specifically, the mass ratio of glass powder to liquid can be 8:2, 6:4, or 7:3. This technical solution further limits the mass ratio of glass powder to liquid. Too high a proportion of glass powder may lead to poor fluidity of the glass slurry, excessively rapid solidification, and failure to tightly fill the mold cavity 2, resulting in pores and decreased strength and fracture toughness. Too low a proportion of glass powder may lead to an excessively thin glass slurry, resulting in excessively high moisture content after drying, making it more prone to uneven shrinkage, deformation, affecting dimensional accuracy, and increased porosity, leading to decreased strength and fracture toughness. A uniformly suspended glass slurry is prepared by mixing glass powder with water, binder, and dispersant in a certain proportion and then ball milling.

[0029] In a preferred embodiment, the slurry comprises, by mass percentage, 95-99% water, 0.5-3.5% dispersant, and 0.5-2% low-carbon alcohol. Further, the dispersant is polyethylene glycol and / or polyvinyl alcohol, and the low-carbon alcohol is ethanol and / or methanol. This technical solution defines the composition of the slurry because it includes water as the main solvent, and the dispersant and low-carbon alcohol ensure uniform suspension and viscosity of the glass slurry, resulting in tight bonding and uniform distribution within the restoration, thus guaranteeing the mechanical properties and uniform dimensional shrinkage of the restoration.

[0030] Understandably, the mass percentage of water can be 96%, 97%, 98% or any value within that range, the mass percentage of dispersant can be 1.0%, 1.5%, 2.0%, 2.5%, 3.0% or any value within that range, and the mass percentage of lower alcohols can be 1.0%, 1.5% or any value within that range.

[0031] In a preferred embodiment, the glass powder comprises, by mass percentage, 65-73% SiO2, 12-20% Li2O, 2-4% ZnO, 3-8% Al2O3, 3-6% K2O, 3-8% P2O5, and 1-5% ZrO2; the slurry comprises 96-98% water, 1.5-3% dispersant, and 1-1.5% low-carbon alcohol.

[0032] In a preferred embodiment, the adhesive removal process includes: removing adhesive at 300-500°C for 1-3 hours; the crystallization sintering conditions include: under vacuum conditions, a sintering temperature of 750-900°C, a heating rate of 15-30°C / min, and a holding time of 0.5-1.5 hours. This technical solution further defines the adhesive removal and crystallization sintering conditions to ensure complete adhesive removal, good crystal growth, and uniform and sufficient shrinkage of the restoration, thereby achieving good mechanical properties and restoration dimensions. It is understood that the adhesive removal temperature can also be any value within the range of 350°C, 400°C, 450°C, and 800°C, 850°C, and 850°C, and the sintering temperature can also be any value within the range of 800°C, 850°C, and 850°C.

[0033] In a preferred embodiment, an intermediate repair is obtained after crystallization and sintering. The surface of the intermediate repair is then polished and glazed to obtain the final repair.

[0034] In a preferred embodiment, conventional process steps such as weighing, melting, water quenching, and crushing are performed according to the formula to crush the glass powder into particles with a diameter of 3-5 μm. The glass powder is mixed with the slurry and stirred for 1-2 hours, then poured into the designed plaster mold 1. After drying, it is removed from the mold and placed in a glue removal furnace at 300-500°C for glue removal for 1-3 hours. Vacuum sintering is then performed in a vacuum sintering furnace at a sintering temperature of 750-900°C, a heating rate of 15-30°C / min, and a holding time of 0.5-1.5 hours. After sintering, the repair body is obtained by polishing and glazing.

[0035] In another aspect, the present invention provides a dental glass-ceramic restoration of the above-mentioned technical solution, wherein the main crystalline phase is lithium disilicate.

[0036] To provide a clearer and more detailed description of the dental glass-ceramic restorations and their preparation methods provided in the embodiments of the present invention, specific embodiments will be described below.

[0037] Examples 1-10 According to the component content shown in Tables 1 and 2 below, take the raw materials of the base glass and mix them thoroughly. Each raw material can be its oxide, carbonate, or phosphate, etc. The mixed raw materials are placed in a platinum crucible and melted in a furnace. The melting temperature is controlled at 1550℃ and the melting time is 60 min to homogenize the glass liquid. Then, it is poured into cold water to obtain broken glass flocs, which are then crushed to a particle size of about 4 μm. Prepare the slurry by mixing water, dispersant, and low carbon alcohol evenly with the crushed glass powder in proportion and stirring for 2 hours. Pour the slurry into the designed plaster mold 1, dry it, remove it from the mold, and place it in a glue removal furnace at 450℃ for 2 hours. Vacuum sintering is then carried out in a vacuum sintering furnace at a sintering temperature of 750-900℃, a heating rate of 15℃ / min, and a holding time of 0.5-1.5 hours. After sintering, the repair body is obtained by polishing and glazing.

[0038] Table 1. Raw material composition of basic glass powder

[0039] Table 2 Basic Raw Material Composition of Slurry

[0040] The process parameters and sample performance indicators under different raw material ratios in Examples 1-10 above are shown in Table 3.

[0041] Table 3. Process parameters and sample performance indicators under different raw material ratios

[0042] Comparative Examples 1-5 According to the composition content shown in Table 4 below, take the raw material components of the melt-processed lithium disilicate, such as oxides, carbonates, or phosphates, and mix them thoroughly. Place the mixed raw materials into a platinum crucible, place the platinum crucible in a furnace for melting, control the melting temperature at 1550℃, and the melting time at 60 min to homogenize the glass melt. Then pour it into cold water to obtain broken glass flocs. After drying the broken glass flocs, put them back into the furnace for melting, control the melting temperature at 1550℃, and the melting time at 60 min. After melting, pour the glass melt into a mold to form it. Demold it 30 min after forming and vacuum sinter it in a vacuum sintering furnace at 640℃. Use CAD / CAM to process the required restoration body, and then sinter it at a sintering temperature of 800-870℃, a heating rate of 15℃ / min, and a holding time of 5-15 min. After sintering, glaze it to obtain the restoration body.

[0043] The composition of lithium disilicate glass ceramic raw materials obtained by the traditional melting method is shown in Table 4 below.

[0044] Table 4 Composition of Lithium Disilicate Glass-Ceramic Raw Materials by Traditional Melting Method

[0045] The performance of the example samples was compared with that of the traditional fused lithium disilicate glass-ceramic samples, and the performance of the traditional fused lithium disilicate glass-ceramic samples is shown in Table 5 below.

[0046] Table 5 Performance Indicators of Lithium Disilicate Glass-Ceramic Samples from the Traditional Melting Method

[0047] The above results show that the performance of the sample in this embodiment is not significantly different from that of the traditional fused lithium disilicate glass-ceramic sample. However, the present invention greatly simplifies the preparation process of the restoration.

[0048] Comparative Example 6 The formulation and preparation method are the same as in Example 1, except that the particle size of the glass powder is 2 μm.

[0049] Comparative Example 7 The formulation and preparation method are the same as in Example 1, except that the particle size of the glass powder is 6 μm.

[0050] The performance indicators of Example 1 and Comparative Examples 6-7 are shown in Table 5.

[0051] Table 5 Performance indicators of Example 1 and Comparative Examples 6-7

[0052] In Comparative Example 6, the glass powder had a particle size of 2 μm. The particle size was too small, which made the restoration prone to uneven shrinkage and deformation after sintering, affecting the final shape and fit of the restoration. The bending strength and fracture toughness also decreased to some extent.

[0053] In Comparative Example 7, the glass powder had a particle size of 6 μm. The particle size was too large, which resulted in a loose structure and high porosity in the green body after drying, making it easy to be damaged. Furthermore, the density, flexural strength, and fracture toughness of the repaired body decreased after sintering.

[0054] like Figure 3 The image shows the XRD pattern of the repair body provided in Example 1. It can be seen from the image that the repair body contains the main crystalline phase Li2Si2O5 and the secondary crystalline phase Li2SiO3.

[0055] In summary, this method allows for the direct fabrication of personalized restorations from the slurry, saving many intermediate processes. Compared to the melting method, it eliminates the need for melting and molding, and a single heat treatment, avoiding issues such as chipping and uneven crystallization during heat treatment. Compared to the sintering method, it directly shapes the final restoration without the need for dry pressing, avoiding the edge chipping problem common in dry pressing methods like sintering. Compared to machinable methods, which require grinding away most of the material, this method requires significantly less material to complete the restoration fabrication. Compared to hot pressing, it omits many intermediate processes for making ceramic blocks, directly shaping the restoration from the slurry, making the process much simpler. The dental glass-ceramic restoration preparation method provided by this invention is simple in process and cost-effective; it avoids, to some extent, the problems of chipping, cracking, and uneven crystallization associated with the melting method; it also avoids, to some extent, the edge chipping problem common in dry pressing methods like sintering; and it directly shapes the final restoration without the need for intermediate ceramic blocks.

Claims

1. A method for preparing a dental glass-ceramic restoration, characterized in that, include: Using digital design methods to create wax models of restorations; The wax pattern of the restoration is embedded in plaster material and then molded to form a plaster mold, the plaster mold having an outwardly protruding grouting port; The cavity of the plaster mold is filled with glass slurry, and the slurry is kept in the injection port until the glass slurry in the cavity of the plaster mold dries to form a hardened blank. The hardened blank is removed and the binder is removed. After the binder is removed, crystallization sintering is performed. The glass slurry includes glass powder, the particle size of which is selected from any value between 3 and 5 μm.

2. The method for preparing a dental glass-ceramic restoration according to claim 1, characterized in that, The wax model of the restoration is enlarged by 20-25% proportionally to the restoration.

3. The method for preparing a dental glass-ceramic restoration according to claim 2, characterized in that, The glass powder comprises, by mass percentage, 60-75% SiO2, 10-25% Li2O, 0-5% ZnO, 0.1-10% Al2O3, 0.1-8% K2O, 0-10% P2O5, and 0-10% ZrO2.

4. The method for preparing a dental glass-ceramic restoration according to claim 2, characterized in that, The glass slurry includes a slurry, and the mass ratio of the glass powder to the slurry is 6-8:2-4.

5. The method for preparing a dental glass-ceramic restoration according to claim 4, characterized in that, The slurry comprises, by mass percentage, 95-99% water, 0.5-3.5% dispersant and 0.5-2% low-carbon alcohol.

6. The method for preparing a dental glass-ceramic restoration according to claim 5, characterized in that, The dispersant is polyethylene glycol and / or polyvinyl alcohol, and the lower alcohol is ethanol and / or methanol.

7. The method for preparing a dental glass-ceramic restoration according to claim 4, characterized in that, The glass powder comprises, by mass percentage, 65-73% SiO2, 12-20% Li2O, 2-4% ZnO, 3-8% Al2O3, 3-6% K2O, 3-8% P2O5, and 1-5% ZrO2; the slurry comprises 96-98% water, 1.5-3% dispersant, and 1-1.5% low-carbon alcohol.

8. The method for preparing a dental glass-ceramic restoration according to claim 1, characterized in that, Debinding includes: Discharge the adhesive at 300-500℃ for 1-3 hours; The crystallization sintering conditions include: sintering temperature of 750-900℃ under vacuum conditions, heating rate of 15-30℃ / min, and holding time of 0.5-1.5 hours.

9. The method for preparing a dental glass-ceramic restoration according to claim 1, characterized in that, After crystallization and sintering, an intermediate repair is obtained. The surface of the intermediate repair is then polished and glazed to obtain the final repair.

10. The dental glass-ceramic restoration according to claim 1, characterized in that, The main crystalline phase of the dental glass-ceramic restoration is lithium disilicate.

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