Dental firing pastes and method of preparing thereof

Abstract

A method for preparing a dental firing paste is also provided, comprising: breaking a plurality of aluminum silicate fibers; mixing glycerin with the broken aluminum silicate fibers until they are uniform and have no separated phases to obtain a dental firing paste, so as to prevent deformation of the restoration during sintering, reduce the color error between the restoration and the teeth in the patient's mouth, and be non-toxic.

Description

[Technical Field]

[0001] This disclosure relates to a dental sintering paste and its preparation method. [Previous Technology]

[0002] In the digital dental fabrication process, the invention and widespread use of oral scanners have replaced physical working models such as impressions and plaster castings with scanned images. During the two steps of strengthening ceramic crystallization and staining in ceramic crowns, dental technicians need to squeeze sintering paste between the metal support pin and the prosthesis (crown) to stabilize the crown and ensure it does not fall off during strengthening and staining. Furthermore, with advancements in dental technology, prostheses have become increasingly thinner. If the inner cavity of the prosthesis lacks sufficient supporting material during ceramic sintering, it is not only prone to falling off and becoming soiled, but may also deform during high-temperature sintering. Due to the thinness of the prosthesis, the color of the abutment teeth in the patient's mouth can negatively affect the final color of the prosthesis.

[0003] In view of this, there is a real need to improve the existing technology. [Summary of the Invention]

[0004] One embodiment of this disclosure provides a dental sintering paste comprising: glycerin and aluminum silicate, wherein the weight ratio of glycerin to aluminum silicate is 6:4 to 9:1.

[0005] In some embodiments, aluminum silicate is zirconium-containing aluminum silicate.

[0006] In some embodiments, the weight ratio of glycerol to aluminum silicate is 7:3 to 8:2.

[0007] In some embodiments, the dental sintering paste further contains pigments.

[0008] In some embodiments, the pigment includes food coloring yellow No. 4, food coloring blue No. 1, food coloring red No. 40, or any combination thereof.

[0009] In some embodiments, the pigments are formulated to produce different colors: wheat color is prepared by mixing 67% by weight of food coloring yellow No. 4, 8% by weight of food coloring blue No. 1, and 25% by weight of food coloring red No. 40; or jasmine color is prepared by mixing 71% by weight of food coloring yellow No. 4, 6% by weight of food coloring blue No. 1, and 24% by weight of food coloring red No. 40; or dark yellowish-brown color is prepared by mixing 75% by weight of food coloring yellow No. 4, 5% by weight of food coloring blue No. 1, and 20% by weight of food coloring red No. 40. % of food coloring Red 40; or chrome yellow, which is 77% by weight of food coloring Yellow 4, 5% by weight of food coloring to make Blue 1, and 18% by weight of food coloring Red 40; or camel, which is 53% by weight of food coloring Yellow 4, 11% by weight of food coloring to make Blue 1, and 35% by weight of food coloring Red 40; or olive, which is 39% by weight of food coloring Yellow 4, 18% by weight of food coloring to make Blue 1, and 43% by weight of food coloring Red 40.

[0010] In some embodiments, the moisture content of the dental sintering paste, the weight lost due to drying at 1 atmosphere and 25°C, tends to balance out in 11 to 13 hours.

[0011] In some embodiments, the fiber diameter of the dental sintering paste is between 15 micrometers and 25 micrometers.

[0012] Another embodiment of this disclosure provides a method for preparing a dental sintering paste, comprising: breaking a plurality of fibers of aluminum silicate; mixing glycerol with the broken fibers of aluminum silicate until homogeneous and free of separated phase to obtain a dental sintering paste, wherein the weight ratio of glycerol to aluminum silicate is 6:4 to 9:1.

[0013] In some embodiments, the step of breaking these fibers of aluminum silicate includes breaking the fibers of aluminum silicate into lengths between 50 micrometers and 250 micrometers.

[0014] In some embodiments, the dental sintering paste does not slip out of the bottle when it is inverted for 12 hours.

[0015] In some embodiments, the method further includes sintering sintering paste, the sintered sintering paste losing 60% to 75% of its weight.

[0016] In some embodiments, the step of mixing glycerol with the broken aluminum silicate fibers includes mixing glycerol, the broken aluminum silicate fibers and food coloring until homogeneous and free of separation phase to obtain a dental sintering paste.

Implementation Method

[0017] To make the description of this disclosure more detailed and complete, illustrative descriptions of embodiments and specific examples of this disclosure are provided below. However, this is not the only form of implementing or using the specific examples of this disclosure. The various embodiments disclosed below can be combined or substituted with each other where advantageous, and other embodiments can be added to one embodiment without further description or explanation. In the following description, many specific details will be set forth in detail to enable the reader to fully understand the following embodiments. However, the embodiments of this disclosure can also be practiced without such specific details.

[0018] In addition, spatial relative terms, such as "down" and "up," are used to conveniently describe the relative relationship of one element or feature to other elements or features in the diagram. These spatial relative terms are intended to include different orientations of the device during use or operation, in addition to those shown in the diagram. The device may be positioned otherwise (e.g., rotated 90 degrees or other orientations), and the spatial relative descriptions used herein may be interpreted accordingly.

[0019] In this document, unless otherwise specified in the text, the words “a” and “the” may refer to one or more. It will be further understood that the words “comprising,” “including,” “having,” and similar terms used herein refer to the features, regions, integers, steps, operations, elements, and / or components described herein, but do not exclude one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof described or additionally described herein.

[0020] Furthermore, when numbers or ranges of numbers are described by the terms "about," "approximately," and the like, the terms are intended to cover numbers within a reasonable range of variations that, as understood by those skilled in the art, inherently occur during manufacturing. For example, based on known manufacturing tolerances associated with manufacturing characteristics (having characteristics associated with numbers), numbers or ranges of numbers encompass a reasonable range including the described numbers, such as within + / - 10% of the described numbers. Furthermore, references to numbers and / or letters may be repeated in various instances in this disclosure. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0021] In some embodiments, a dental sintering paste is provided, comprising glycerin and aluminum silicate, wherein the weight ratio of glycerin to aluminum silicate is 6:4 to 9:1. In some embodiments, the weight ratio of glycerin to aluminum silicate is 7:3 to 8:2.

[0022] In some embodiments, the aluminum silicate is zirconium-containing aluminum silicate. In some embodiments, the dental sintering paste comprises glycerin, aluminum silicate, and zirconium oxide. In some embodiments, the weight ratio of zirconium oxide to aluminum silicate is 95:5 to 75:25, for example, 95:5, 90:10, 85:15, 80:10, 75:25, or any value between any two of these values. In some embodiments, the weight ratio of zirconium oxide to aluminum silicate is 8:2.

[0023] In some embodiments, the fiber diameter of the dental sintering paste is between 15 micrometers and 25 micrometers, for example 15 micrometers, 16 micrometers, 17 micrometers, 18 micrometers, 19 micrometers, 20 micrometers, 21 micrometers, 22 micrometers, 23 micrometers, 24 micrometers, 25 micrometers, or any value between any two of these values.

[0024] In some embodiments, the moisture content of the dental sintering paste, the weight loss due to drying at 1 atm and 25°C, tends to balance out in 11 to 13 hours, for example, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours, or any value between any two of these values. In some embodiments, the weight loss is between 45% and 55%, for example, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, or any value between any two of these values.

[0025] In some embodiments, the dental sintering paste further comprises a pigment. In some embodiments, the weight percentage of the food coloring is from 0.1 wt% to 5.0 wt%, such as 1.0 wt%, or any value between any two of these values, based on 100% of the total weight of the dental sintering paste.

[0026] In some embodiments, a method for preparing a dental sintering paste is provided, comprising: breaking a plurality of fibers of aluminum silicate; mixing glycerol with the broken fibers of aluminum silicate until homogeneous and free of separated phase to obtain a dental sintering paste, wherein the weight ratio of glycerol to aluminum silicate is 6:4 to 9:1.

[0027] In this article, "uniform without phase separation" means that there is no obvious agglomeration or phase separation under visual observation. For example, there is no oil-powder separation phenomenon, achieving uniform molding.

[0028] In some embodiments, the sintering paste is inverted in the bottle for at least 20 minutes or at most 24 hours without falling, for example 20 minutes, 30 minutes, 40 minutes, 50 minutes, 1 hour, 2 hours, 3 hours, 6 hours, 9 hours, 12 hours, 24 hours, or any value between any two of these values.

[0029] In some embodiments, the step of breaking these fibers of aluminum silicate includes breaking the fibers of aluminum silicate into lengths between 50 micrometers and 250 micrometers.

[0030] In some embodiments, the method further includes sintering a sintering paste, the sintered sintering paste losing 60% to 75% of its weight, for example 60%, 65%, 70%, 75%, or any value between any two of these values.

[0031] In some embodiments, a dental prosthesis is provided, comprising: a crown body and a dental sintering paste as described above. The crown body includes a shell and a cavity located within the shell, the dental sintering paste being filled in the cavity.

[0032] Currently, there is no tinted sintering paste, and the thinness of the prosthesis causes the color of the abutment tooth to affect the final color of the prosthesis. How to tint the sintering paste to match the abutment tooth shade guide so as not to cause color difference during the final sintering of the prosthesis crown is a challenge. Therefore, this disclosure provides a dental sintering paste that prevents deformation of the prosthesis during sintering, reduces color error between the prosthesis and the patient's teeth, and is non-toxic.

[0033] The following examples and experimental cases are provided to illustrate the dental sintering paste disclosed herein in more detail. However, they are only for illustrative purposes and are not intended to limit the scope of the disclosure. The scope of protection of the disclosure shall be defined by the appended claims.

[0034] Although the method disclosed herein is described below using a series of operations or steps, the order in which these operations or steps are shown should not be construed as a limitation of this disclosure. For example, some operations or steps may be performed in a different order and / or simultaneously with other steps. Furthermore, it is not necessary to perform all illustrated operations, steps, and / or features to achieve the implementation of this disclosure. In addition, each operation or step described herein may include several sub-steps or actions.

[0035] For clarity, features and elements that are known in the field and are not essential for understanding the principles described will be omitted.

[0036] Example

[0037] Preparation Example 1

[0038] First, zirconium-containing aluminum silicate (or refractory cotton, with a zirconium oxide to aluminum silicate weight ratio of 8:2) is obtained, and its compound fibers are broken into lengths between 50 micrometers and 250 micrometers. Next, glycerin is mixed with these broken aluminum silicate fibers (with or without optional addition of food coloring) until homogeneous and free of separated phases to obtain a dental sintering paste. Glycerin and zirconium-containing aluminum silicate are mixed in different weight ratios (see Table 1 below). If food coloring is selectively added, the addition amount is trace to negligible. Specifically, the weight percentage of food coloring is 1.0 wt% of 100% of the total weight of the dental sintering paste.

[0039] Table 1. Weight ratio of glycerol and aluminum zirconium silicate serial number weight ratio glycerin weight percentage Aluminum silicate containing zirconium weight percentage 1 5:5 50% 50% 2 6:4 60% 40% 3 7:3 70% 30% 4 8:2 80% 20% 5 9:1 90% 10%

[0040] When the ratio of glycerol to aluminum zirconium silicate is 5:5, the mixture is extremely dry and cannot effectively aggregate into shape. A sample with a ratio of 6:4 can aggregate into shape but is relatively hard. A ratio of 7:3 exhibits appropriate viscosity, plasticity, and support. A ratio of 8:2 results in a moist sample surface. A ratio of 9:1 causes the sample to slip off the metal pins, indicating that it cannot provide adequate support for the crown. Subsequent examples use a glycerol to aluminum zirconium silicate ratio of 7:3 as an example; without added food coloring, it is called a colorless sintering paste; with added food coloring, it is called a support-colored sintering paste.

[0041] In this preparation example, edible yellow pigment (Tartrazine), edible blue pigment (Brilliant blue FCF), and edible red pigment (Allura Red AC) were selected as the three primary colors of the pigments. These edible pigments were added to the sintering paste in different proportions, and the colors of the abutments in the patient's mouth were prepared by referring to the Ivoclar Vivadent IPS Natural Die Material shade guide and the VITA classical A1-D4® shade guide. The mixing proportions are shown in Table 2 below. The sintering paste for the support teeth was named according to color as follows: (a) Wheat, (b) Jasmine, (c) Dark Goldenrod, (d) Chrome Yellow, (e) Camel, and (f) Olive, corresponding to VITA A1, VITA A3, VITA ND4, VITA ND6, VITA ND8, and VITA ND9, respectively. Please refer to Figure 10 for the mixing results. For example, glycerin is 50 parts by weight, aluminum zirconium silicate is 50 parts by weight, and pigment is 1 part by weight; glycerin is 60 parts by weight, aluminum zirconium silicate is 40 parts by weight, and pigment is 1 part by weight; glycerin is 70 parts by weight, aluminum zirconium silicate is 30 parts by weight, and pigment is 1 part by weight; glycerin is 80 parts by weight, aluminum zirconium silicate is 20 parts by weight, and pigment is 1 part by weight; or glycerin is 90 parts by weight, aluminum zirconium silicate is 10 parts by weight, and pigment is 1 part by weight.

[0042] Table 2. Proportion of edible pigments in 6 types of support tooth color sintering pastes name Food coloring yellow No. 4 Food coloring, blue No. 1 Food coloring red No. 40 Total weight percentage wheat color 67% 8% 25% 100% Jasmine 71% 6% twenty four% 100% dark yellowish brown 75% 5% 20% 100% Chrome yellow 77% 5% 18% 100% Camel 53% 11% 35% 100% olive green 39% 18% 43% 100%

[0043] Example 1 Microstructure

[0044] Since the Scanning Electron Microscope (SEM) instrument is only suitable for dry samples, the commercially available (a) VITA firing paste (VITA Zahnfabrik), (b) Sirona Speedpaste (Dentsply Sirona), (c) Aidite firing paste (Aidite), (d) IPS object fix (Ivoclar vivadent), (e) DD contrast firing paste (Dental Direkt), and (f) colorless sintering paste of Preparation Example 1 were first sintered in the furnace at 850°C for 25 minutes before being placed in the SEM instrument for imaging.

[0045] Regarding the colorless sintering paste, the results in Figure 20 show that, except for group (d) IPS, the surface structures of the other sintering pastes are the same, exhibiting a fibrous structure, which is consistent with the observations under an optical microscope. However, the IPS sintering paste appears as a powdery granule. This result can be compared with observations during daily use; when extruding the IPS sintering paste, the paste texture is noticeably harder and more solid. Conversely, the other five sintering pastes are relatively easier to extrude.

[0046] In the six types of self-made support tooth color sintering pastes ((a) wheat color, (b) jasmine color, (c) dark yellowish brown, (d) chrome yellow, (e) camel color, and (f) olive color), the results in Figure 30 show that, as observed under an optical microscope, the surface morphology of the six different colored sintering paste samples all exhibits a cotton fiber-like appearance.

[0047] Based on the SEM results in Figure 20 and Figure 30, five samples were taken repeatedly to calculate the diameter of the sintering paste fibers or powder particles (as shown in Figure 40). In the commercially available and colorless sintering paste of Preparation Example 1 (Figure 40, left), except for the VITA sintering paste which had a lower fiber diameter (19.2 μm), the fiber diameters of the other three brands ranged from 20.4 μm to 22 μm, while the average fiber diameter of the colorless sintering paste of Preparation Example 1 was 21.44 ± 1.1 μm. In the six types of colorless sintering paste of Preparation Example 1 (Figure 40, right), the average fiber diameter ranged from 19.0 μm to 20.8 μm, which was not significantly different from the 21.44 μm of the colorless sintering paste of Preparation Example 1.

[0048] Example 2 Energy Dispersive Spectrometry Analysis

[0049] The commercially available sintering paste and the sintering paste from Preparation Example 1 were analyzed using an energy dispersive spectrometer (EDS). The analytical results are shown in Figure 5.50. The sintering paste is mostly composed of elements such as carbon, oxygen, aluminum, and silicon. Trace amounts of sodium were detected in three of the sintering pastes: Aidite, DD, and the colorless sintering paste from Preparation Example 1. The colorless sintering paste from Preparation Example 1 used refractory cotton containing aluminosilicate zirconium silicate, so the EDS results showed additional zirconium content. Among all the sintering paste samples, aluminum had the highest content, followed by silicon and oxygen.

[0050] Similarly, in the EDS spectra of the six color-colored sintering pastes prepared in Example 1 (Figure 6, 60), the elemental composition included carbon, oxygen, sodium, aluminum, silicon, zirconium, etc., the same as that of the colorless sintering paste prepared in Example 1. The Au* appearing in the spectrum represents gold, which is due to a thin gold film being deposited on the sample before analysis, and is not a component of the sample itself. The results show that the peak distribution of these six color-colored sintering pastes is the same, indicating that the addition of food coloring to the sintering paste has no effect on the elemental composition.

[0051] Example 3 Weight difference before and after sintering

[0052] For different commercially available brands and the sintering paste samples from Preparation Example 1, the initial weight was set to 1.0 ± 10% g and placed on a sintering pad. Then, following the manufacturer's recommended staining and sintering program, the temperature was set, and the sample, along with the sintering pad and sintering tray, was placed in a ceramic furnace and the program (Programat CS, Ivoclar Vivadent, Germany) was started. After the furnace sintering program was completed, the sample was removed after the temperature decreased, and the weight of the sintered sample was weighed again. This process was repeated three times, and the average and standard deviation of the weight difference before and after sintering were recorded. The formula is as follows: Weight difference = Δw = (Original weight - Weight after sintering) / Original weight (%). This time, no dental crowns were involved; the sintering paste was simply placed in a ceramic furnace and sintered under the same conditions as in Example 1.

[0053] The experimental results show that the sintering paste will experience weight loss after sintering. Among the commercially available sintering pastes (Figure 7, 70 left), the IPS sintering paste has the smallest weight loss compared to other sintering pastes, approximately 24%. Visual observation and optical microscopy clearly show that the texture of the IPS sintering paste is different from other sintering pastes. Therefore, this result may be because the composition of the IPS sintering paste is not the same as other brands of sintering pastes, which consist of refractory cotton and glycerin. The weight loss of the other four commercially available sintering pastes is approximately 80% of their original weight, suggesting that 80% of the sintering paste's composition is solvent, and only 20% is cotton. In contrast, the sintering paste prepared in this experiment (Preparation Example 1 colorless sintering paste and Figure 7, 70 right) has a weight loss of approximately 70% after sintering, suggesting that 70% of the composition of Preparation Example 1 sintering paste is solvent, and only 30% is refractory cotton. This result is consistent with the 7:3 mixing ratio of glycerin and refractory cotton used in Preparation Example 1 sintering paste. Furthermore, the percentage of weight loss after sintering of the six types of sintering pastes was very similar, all around 70%, indicating that the type and amount of color dye did not affect the residual amount of the sintering paste after sintering in the furnace.

[0054] Example 4 Thermal Property Analysis

[0055] Analysis was performed using a simultaneous thermogravimetric analyzer (STA PT 1000, LINSEIS) with both a thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC). Less than 0.005 g of the sintered commercially available sample and the sintered paste sample from Preparation Example 1 were placed in a dedicated crucible and heated from room temperature at a maximum temperature of 1000°C. The weight change (Delta m, Δm) and DSC phase change curves of the samples were measured.

[0056] As can be observed from the thermogravimetric analysis (TGA) curves in Figures 8.80 and 9.90, the weight of the sample increases with increasing temperature. This may be due to the combination of the gas introduced into the STA instrument with the cotton, resulting in an increase in weight. However, no obvious peak or phase change temperature is observed in the DSC curves. Since the thermogravimetric analysis instrument can only accept dry samples, and the sintering paste of Preparation Example 1 was in paste form before sintering in the furnace, it was not a dry sample and could not be placed in the instrument. Therefore, this result may be because both the commercially available and Preparation Example 1 sintering paste samples were first sintered in a ceramic furnace, and the sintering paste itself has refractory properties, capable of withstanding high temperatures of 900°C to 1400°C without melting or vaporizing. However, the maximum temperature limit of the STA instrument is only 1000°C, so the sintering paste sample will not undergo a phase change, and therefore the phase change of the sintering paste cannot be observed in the results.

[0057] Example 5 Moisturizing effect

[0058] When using sintering paste, it gradually dries out over time. One gram of each of the commercially available and Preparation Example 1 sintering pastes were placed at 1 atmosphere and room temperature (25°C). The weight loss due to drying of the sintering paste samples was recorded over time (0.5 hours, 1 hour, 3 hours, 4.5 hours, 6 hours, 9 hours, 12 hours, 16 hours, 20 hours, and 1 day, 3 days, 7 days, and 14 days). This loss was termed drying weight loss.

[0059] The results in the upper left of Figure 100 show that the commercially available sintering paste and the sintering paste of Preparation Example 1 tend to reach equilibrium after 1 day (24 hours). The equilibrium points of VITA, Sirona, Aidite, IPS, DD, and the colorless sintering paste of Preparation Example 1 are 0.2204 g, 0.2245 g, 0.2694 g, 0.8411 g, 0.2315 g, and 0.4866 g, respectively. Further observation of the data in the upper right of Figure 100 within 20 hours shows that the IPS sintering paste dries earlier than the other sintering pastes, reaching equilibrium at about 4.5 hours, with an equilibrium point around 0.84 g. The colorless sintering paste of Preparation Example 1 reaches equilibrium at about 12 hours, with an equilibrium point around 0.55 g. The other four sintering pastes (VITA, Sirona, Aidite, and DD) continue to decrease in weight until the end of 20 hours, and have not yet reached equilibrium.

[0060] In the moisture retention test, the weight losses of VITA, Sirona, Aidite, IPS, DD, and the colorless sintering paste of Preparation Example 1 when naturally dried to equilibrium were approximately 78.02%, 78.78%, 74.10%, 17.00%, 77.78%, and 53.04%, respectively. It can be seen that compared with complete drying, IPS and the colorless sintering paste of Preparation Example 1 lost less weight when naturally dried to equilibrium, which means that these two sintering pastes have relatively good moisture retention.

[0061] The results in the lower left of Figure 100 show that the six types of tooth-colored sintering pastes prepared in Example 1 rapidly decreased to about 0.5 mg within one day and tended to reach equilibrium. Moreover, the curves of the six types of tooth-colored sintering pastes observed in hours or days almost overlapped (lower left and lower right of Figure 100), indicating that color has no significant effect on the water retention of the sintering paste.

[0062] In the moisture retention test, the weights of the six types of sintered pastes in the support teeth color after drying in the atmosphere were 0.5027 g, 0.5142 g, 0.5224 g, 0.4968 g, 0.5043 g and 0.5004 g respectively, which means that the weight loss when approaching equilibrium was approximately 49.89%, 51.13%, 50.92%, 50.59%, 51.20% and 50.60% respectively.

[0063] Example 6 Adhesion Test

[0064] Three different ceramic blocks were used: lithium disilicate glass-ceramic (Ivoclare.maxCAD), zirconia ceramic (Aierchuang ST), and feldspar glass-ceramic (VITA MarkII). First, the green-state Erchuang ST zirconia ceramic blocks were strengthened according to the manufacturer's recommended sintering temperature (Miyazaki, Nakamura, Matsumura, Ban, & Kobayashi, 2013; Saridag, Tak, & Alniacik, 2013). Then, each of the three ceramic blocks was cut into 12 1 mm thick sheets using a diamond cutter, and commercially available colorless sintering paste, the colorless sintering paste of Preparation Example 1, and the six different colored sintering pastes of Preparation Example 1 were extruded. Next, the ceramic sheets were evenly pressed onto sintering pads and sintered in the furnace. The sintering parameters were set according to the manufacturer's recommended coloring heating rate, maximum temperature, and holding time. After sintering, the dried sintering paste was gently removed, and the degree of adhesion remaining on the ceramic sheets was observed.

[0065] Table 3. Adhesion ratios of colorless and 6 types of support tooth sintering pastes prepared in Example 1. VITA Sirona Aidite IPS DD Preparation Example 1: Colorless Sintering paste e.Max CAD 5% 76% 3% 0% 8% 7% Upcera ST 0% 0% 0% 0% 0% 0% VITA Mark II 0% 0% 0% 0% 0% 0% wheat color Jasmine dark yellowish brown Chrome yellow Camel olive green e.Max CAD 10% 11% 10% 20% 12% 0% Upcera ST 0% 0% 0% 8% 0% 0% VITA Mark II 0% 0% 0% 0% 0% 0%

[0066] As shown in Table 3 and Figure 11 above, all e.Max CAD ceramic blocks, regardless of the type of sintering paste, exhibit significant residue. If the e.Max CAD ceramic blocks are excluded, and only the Upcera ST and VITA Mark II ceramic blocks are observed, the IPS sintering paste shows the most severe adhesion residue. The other five sintering pastes, excluding the IPS paste, demonstrate good anti-adhesion properties on the ceramic tiles.

[0067] As shown in Table 3 and Figure 11 below, the results indicate that in the six types of colored sintering pastes for the support teeth of Preparation Example 1, the colored sintering pastes completely evaporated after sintering in the furnace, leaving only the original white color. Similar to the results of commercially available sintering pastes, all six types of colored sintering pastes for the support teeth of Preparation Example 1 left noticeable residues on the e.Max CAD ceramic block. If the e.Max ceramic block is disregarded, all six colors of sintering paste exhibited good anti-adhesion properties on the ceramic block after sintering.

[0068] Example 7 Optical Property Analysis of Colored Sintering Paste

[0069] According to the definition of the International Commission on Illumination (CIE), color difference (ΔE) is the square root of the sum of squares of the deviations of the test object from the standard object's L, a, b values. The formula is: ΔE = 0. The value of ΔE is between 0 and 100. When ΔE = 0, it means that there is no difference between the color of the test object and the reference color; while when ΔE = 100, it means that the color of the test object is completely distorted from the reference color. According to the research of Douglas et al., this embodiment sets the standard perception threshold as ΔE = 2.6. When ΔE < 2.6, it means that the color difference cannot be distinguished by the human eye. When ΔE ≤ 5.5, it is considered to be within the clinically acceptable range of color difference.

[0070] This experiment was divided into three groups based on different color reference materials: (a) A3 resin abutment teeth, (b) air, and (c) colorless sintering paste were placed inside the crown of the central incisor. The aim was to observe the color difference between (a) using A3-colored abutment teeth as the standard value and applying sintering paste of six different abutment colors to the crown; (b) the color difference between staining the crown directly without sintering paste and staining it after applying the sintering paste of the six abutment colors from Preparation Example 1; and (c) the color difference between staining the crown using the colorless sintering paste from Preparation Example 1 and staining it after applying the sintering paste of the six abutment colors from Preparation Example 1. In this embodiment, one group of reference materials was set as (a) A3 resin abutment teeth. (b) and (c) can be considered as the color differences caused when the abutment teeth in the patient's mouth are of these six colors.

[0071] As shown in Figures 120(a) and (c), the darker the color inside the crown, the greater the color difference (ΔE) on the crown surface. The different colors of the abutments within the crown clearly demonstrate the variation and difference in crown color. Interestingly, when the baseline color is when no object is placed inside the crown (Figure 120(b)), the color difference (ΔE) increases as the color of the sintering paste inside the crown becomes lighter. This result may be because when no object is placed inside the crown, the inner crown will have a shadow, and this shadow effect is closer to that of the darker abutments.

[0072] Overall, regardless of the object placed in the inner crown, when the crown thickness is 1.5mm, the color difference is significantly smaller than when the crown thickness is 1.0mm and 0.5mm, and decreases with increasing thickness. This shows that the thinner the crown, the greater the influence of the abutment color on the crown surface color. In other words, when the dental technician is staining, if the crown is filled with white sintering paste or if there is only air but the abutment color in the patient's mouth is one of the six abutment colors, the color difference ΔE is large and significant. Therefore, the advantage of using colored sintering paste is that it gives the crown a realistic oral appearance before staining, and after staining, it not only presents an excellent color but also retains the translucency of a natural tooth.

[0073] Example 8

[0074] This study used a colorimetric method (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) to evaluate the biocompatibility of the commercially available and sintered paste of Preparation Example 1. Osteoblastoid cells (MG63) were seeded in 24-well culture dishes, with 5 × 10⁴ cells per well, and cultured for 18 hours in a cell culture incubator at 37°C and 5% CO₂. The culture medium was then replaced with the extract of the sample, and cultured for 1, 3, and 7 days. At different time points, the culture dishes were removed, all DMEM was removed, and 1 mL of DMEM containing 10% MTT was added and reacted in the dark for 4 hours. Then, all solution was removed, and DMSO was added to dissolve and crystallize. 100 μL / well of the solution was then placed in a 96-well culture dish, and the absorbance (OD) at wavelengths of 563-650 nm was read using an ELISA reader.

[0075] As shown in Figure 130, after 7 days of culture, the absorbance of the control group (culture medium without added samples) was 0.72 ± 0.12, while the cell viability of all sintering pastes was good. Except for VITA, which was slightly lower at 0.71 ± 0.03, the absorbance values ​​of the other sintering pastes were all greater than the control group's 0.72. It is worth noting that the absorbance of the colorless sintering paste of Preparation Example 1 was the highest, at 0.96 ± 0.02, indicating that it had the best cell viability and the lowest toxicity. This result may be because the composition of the colorless sintering paste of Preparation Example 1 is simpler than that of other brands of sintering pastes.

[0076] Although the present disclosure has been disclosed above with reference to embodiments, it is not intended to limit the present disclosure. Anyone skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0077] The various aspects of this disclosure will be most readily understood when read in conjunction with the accompanying drawings. It should be noted that, according to industry standard operating procedures, the various feature structures may not be drawn to scale. In fact, for clarity of explanation, the dimensions of various feature structures can be arbitrarily increased or decreased. To make the above and other objects, features, advantages, and embodiments of this disclosure more apparent and understandable, the accompanying drawings are described as follows: Figure 1 shows a schematic diagram of a colorimetric plate corresponding to different sintering paste colors according to one embodiment of this disclosure. Figure 2 shows an electrochemical display of the surface structure of commercially available and homemade colorless sintering pastes according to one embodiment of this disclosure. Figure 3 shows an electrochemical display of the surface structure of a homemade tooth-colored sintering paste according to one embodiment of this disclosure. Figure 4 shows a bar chart of the fiber diameter of commercially available and homemade colorless and tooth-colored sintering pastes according to one embodiment of this disclosure. Figure 5 shows the energy dispersive spectral distribution of commercially available and homemade colorless sintering pastes according to one embodiment of this disclosure. Figure 6 illustrates the energy dispersive spectral distribution of the homemade abutment-colored sintering paste according to one embodiment of this disclosure. Figure 7 illustrates the percentage weight loss after sintering of commercially available and homemade colorless and abutment-colored sintering pastes according to one embodiment of this disclosure. Figure 8 illustrates the thermogravimetric / microdifferential scanning calorimetric analysis results of commercially available and homemade colorless sintering pastes according to one embodiment of this disclosure. Figure 9 illustrates the thermogravimetric / microdifferential scanning calorimetric analysis results of the homemade abutment-colored sintering paste according to one embodiment of this disclosure. Figure 10 illustrates the natural drying rate of commercially available and homemade colorless and abutment-colored sintering pastes according to one embodiment of this disclosure. Figure 11 illustrates the surface adhesion of commercially available and homemade colorless and abutment-colored sintering pastes according to one embodiment of this disclosure. Figure 12 illustrates the color differences between a crown filled with six kinds of homemade abutment-colored sintering pastes and a crown filled with (a) A3 abutment, (b) only air, and (c) white sintering paste according to one embodiment of this disclosure. Figure 13 illustrates the cell viability of commercially available and homemade colorless sintering pastes according to one embodiment of this disclosure. [Biomaterial Storage]

[0079] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A dental sintering paste comprising: glycerin; and aluminum silicate, wherein the weight ratio of the glycerin to the aluminum silicate is 6:4 to 9:

1.

2. The dental sintering paste as described in claim 1, wherein the aluminum silicate is zirconium-containing aluminum silicate.

3. The dental sintering paste as claimed in claim 1, wherein the weight ratio of the glycerin to the aluminum silicate is 7:3 to 8:

2.

4. The dental sintering paste as described in claim 1 further contains pigments.

5. The dental sintering paste as described in claim 4, wherein the pigment comprises food coloring yellow 4, food coloring blue 1, food coloring red 40, or any combination thereof.

6. The dental sintering paste as described in claim 5, wherein the pigment is used to formulate different colors: wheat color is formulated with 67% by weight of the food coloring yellow 4, 8% by weight of the food coloring blue 1, and 25% by weight of the food coloring red 40; or jasmine color is formulated with 71% by weight of the food coloring yellow 4, 6% by weight of the food coloring blue 1, and 24% by weight of the food coloring red 40; or dark yellowish-brown color is formulated with 75% by weight of the food coloring yellow 4, 5% by weight of the food coloring blue 1, and 20% by weight of the food coloring red 40. Alternatively, chrome yellow can be mixed with 77% by weight of the food coloring No. 4, 5% by weight of the food coloring to create Blue No. 1, and 18% by weight of the food coloring No. 40; or camel can be mixed with 53% by weight of the food coloring No. 4, 11% by weight of the food coloring to create Blue No. 1, and 35% by weight of the food coloring No. 40; or olive can be mixed with 39% by weight of the food coloring No. 4, 18% by weight of the food coloring to create Blue No. 1, and 43% by weight of the food coloring No.

40.

7. The dental sintering paste as claimed in claim 1, wherein the moisture content of the dental sintering paste, by weight loss due to drying at 1 atmosphere and 25°C, tends to balance within 11 to 13 hours.

8. The dental sintering paste as claimed in claim 1, wherein the fiber diameter of the dental sintering paste is between 15 micrometers and 25 micrometers.

9. A method for preparing a dental sintering paste, comprising: breaking a plurality of aluminum silicate fibers; mixing glycerol with the broken aluminum silicate fibers until homogeneous and free of separated phase to obtain the dental sintering paste, wherein the weight ratio of the glycerol to the aluminum silicate is 6:4 to 9:

1.

10. The method as claimed in claim 9, wherein the step of breaking the aluminum silicate fibers comprises breaking the aluminum silicate fibers into fibers with a length between 50 micrometers and 250 micrometers.

11. The method as described in claim 9, wherein the dental sintering paste does not slip when the bottle is inverted for 12 hours.

12. The method as described in claim 9 further comprises sintering the sintering paste, wherein the sintered sintering paste loses 60% to 75% of its weight.

13. The method as claimed in claim 9, wherein the step of mixing the glycerol with the broken aluminum silicate fibers comprises mixing the glycerol, the broken aluminum silicate fibers, and food coloring until homogeneous and free of separating phase, to obtain the dental sintering paste.

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