JP6537256B2 - Glass block, method of manufacturing glass block, and method of manufacturing dental prosthesis - Google Patents

Description

  The present invention relates to a glass block.

  The glass block is obtained by processing glass ceramics into a block shape and is ground to a shape of a dental prosthesis or the like (see, for example, Patent Document 1). As a glass block, in order to efficiently carry out the grinding process in a short time, it is desirable that the glass block has excellent grindability.

Patent No. 4777625 gazette

  An object of the present invention is to provide a glass block having excellent grindability.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining that the present inventors might solve the said subject, they found the solution means which consists of the following structures, and came to complete this invention.
(1) consists of glass ceramic semi-crystalline state, and in cross-section, internal 30,000 pores with a diameter 0.1~0.5μm in pieces / mm ² or more and Nde contains, in terms of oxide, Si 63 A glass block characterized by containing 8 to 74.3% by mass, Al at 3.7 to 21.8% by mass, and Li at a ratio of 3.0 to 14.3% by mass .
(2) The glass block according to (1), which contains 35,000 to 700,000 pores / mm ^{2 of the} pores.
(3) The glass block according to (1) or (2), which contains 600,000 to 700,000 pores / mm ^{2 of the} pores.
(4) The glass block according to any one of the above (1) to (3) , which is for a dental prosthesis.
(5) 63.8 to 74.3 mass% of Si, 3.7 to 21.8 mass% of Al, and 3.3 to 24.3 mass% of Al in terms of oxides under melting conditions including the following (I) and (II) . The glass ceramic raw material which is contained at a ratio of 0 to 14.3% by mass is melted, and in the cross section, it is a semi-crystallized state including pores of diameter 0.1 to 0.5 μm at least 30,000 / mm ² or more method of manufacturing features and to Ruga Las block to the glass ceramic.
(I) Melting temperature: 1300 to 1600 ° C
(II) Melting time: less than 2 hours
(6) The method for producing a glass block according to (5) , wherein the melting condition further comprises the following (III) :
(III) Heating rate: 100 ° C / hour or less
(7) the (5) or the semi-crystalline state glass ceramics to the crystalline state after grinding the shape of the dental prosthesis a glass block manufactured by the manufacturing method of a glass block according to (6) Method of manufacturing a dental prosthesis characterized by

  According to the present invention, there is an effect that the grinding performance is excellent.

It is a flowchart which shows the manufacturing method of the dental prosthesis which concerns on one Embodiment of this invention. (A) shows sample No. 1 of the example. It is the electron micrograph which expanded the pore of 1, and (b) is sample No. of an Example. It is the electron micrograph which expanded the pore of 2.

<Glass block and dental prosthesis>
Hereinafter, a glass block and a dental prosthesis according to an embodiment of the present invention will be described.

  The glass block of the present embodiment is for a dental prosthesis. Examples of dental prostheses include inlays, crowns, bridges, dentures, upper structures of dental implants, etc. As upper structures, there are, for example, crowns, bridges, dentures, etc. joined to dental implants. Examples include, but are not limited to.

  Examples of the shape of the glass block include, but not limited to, a rectangular parallelepiped having a length of 10 to 15 mm, a width of 10 to 15 mm, and a height of 15 to 20 mm. The glass block is a concept including other shapes other than the rectangular parallelepiped as long as it can be ground to the desired shape of the dental prosthesis. When the glass block is a rectangular parallelepiped, corner portions may be rounded.

The glass block of the present embodiment is made of glass ceramics in a semi-crystallized state. The semi-crystallization state is a state in which crystallization can be further advanced by heat treatment, and means that the degree of crystallization is 20 to 60%. The degree of crystallinity is calculated from the ratio of the crystal components in the mixed sample obtained by preparing a mixed sample in which a known amount of internal standard substance is added to the sample of glass ceramic, and the powder X-ray diffraction result is Rietveld analysis. Value. Examples of the internal standard substance include Cr ₂ O _{3 and the} like.

Here, the glass block of the present embodiment has 30,000 pieces / mm ² or more, preferably 35,000 to 700,000 pieces / mm ² of pores having a diameter of 0.1 to 0.5 μm in its inside, more preferably Contains 600,000 to 700,000 pcs / mm ² . According to such a configuration, since peeling of the glass occurs from the pores at the time of the grinding process, it is possible to obtain excellent grindability and, as a result, to reduce the load applied to the grinding apparatus. Therefore, while being able to perform grinding processing efficiently in a short time, wear of a grinding tool can be reduced.

  The pores are preferably uniformly present inside the glass block. According to such a configuration, the above-described effects can be efficiently obtained. Also, it is preferred that pores larger than 0.5 μm in diameter do not exist inside the glass block. According to such a configuration, the occurrence of chipping or cracking during grinding can be suppressed.

  The pores can be analyzed as follows. First, a glass block is broken with a mortar or the like, and the fractured surface is observed with an electron microscope at a magnification of about 10,000 to 100,000. Next, the maximum diameter of each of the plurality of pores exposed to the fracture surface is measured, and the number of pores having a maximum diameter of 0.1 to 0.5 μm among the plurality of pores is counted. At this time, the number of pores is counted in the range of 20 μm × 20 μm. Then, the number of pores per unit square mm may be calculated from the number of pores counted.

  On the other hand, the glass block preferably contains Si, Al and Li, and the content of Si is preferably 63% by mass or more in terms of oxide with respect to the total amount of the glass block. The glass block preferably contains 63 to 75% by mass of Si, 3 to 22% by mass of Al, and 3 to 15% by mass of Li in terms of oxide with respect to the total amount of the glass block, the oxide More preferably, it contains 67 to 75% by mass of Si, 3 to 8% by mass of Al, and 11 to 15% by mass of Li in terms of conversion. The glass block may contain, for example, elements such as P, Zr, Mg, Zn, V, Fe, Mn, Ce, Ti, K, etc. in addition to Si, Al, Li.

Si, Al and Li are usually present in the glass block in the form of oxides, ie in the form of SiO ₂ , Al ₂ O ₃ and Li ₂ O. The contents of Si, Al and Li can be measured by ICP (Inductively Coupled Plasma) emission spectroscopy. That is, the content (mass%) of Si, Al and Li in the glass block is measured by ICP emission spectrometry, and the content in terms of SiO ₂ , Al ₂ O ₃ and Li ₂ O ( It may be converted to mass%). The other elements in the glass block can be measured in the same manner.

  The dental prosthesis of the present embodiment is obtained by grinding the above-mentioned glass block into the shape of a dental prosthesis and then crystallizing it from the semi-crystallized glass ceramic. Since the glass block is excellent in grindability as described above, it can be ground to the shape of a dental prosthesis with high processing accuracy. Moreover, since the strength is improved by changing the glass ceramic from the semi-crystallized state to the crystallized state, the dental prosthesis of the present embodiment can exhibit excellent strength. The crystallization state means that the degree of crystallinity is 70 to 90%. The degree of crystallinity is a value measured by the same measurement method as described for the semi-crystallized state.

<Method of manufacturing glass block and dental prosthesis>
Next, a method of manufacturing a glass block and a dental prosthesis according to an embodiment of the present invention will be described in detail with reference to FIG.

As shown in FIG. 1, first, at step S1, the glass ceramic raw material is melted. Examples of glass ceramic raw materials include SiO ₂ , Al ₂ O ₃ , P ₂ O ₅ , ZrO ₂ , MgO, ZnO, V ₂ O ₅ , Fe ₂ O ₃ , MnO, CeO ₂ , TiO ₂ , Li ₂ O, K Examples include oxides such as ₂ O and metal carbonates that form these oxides, but are not limited thereto. Among the exemplified glass ceramic materials, P ₂ O ₅ , V ₂ O ₅ and TiO ₂ function as nucleating agents and CeO ₂ functions as a fining agent, but nucleating agents and fining agents are limited thereto is not. The glass ceramic material is preferably in the form of powder.

  Here, the number of pores described above can be adjusted mainly by the melting conditions when melting the glass ceramic raw material. Specifically, when the melting temperature when melting the glass ceramic material is increased, the number of pores tends to be reduced. Conversely, when the melting temperature is lowered, the number of pores tends to increase. As a melting temperature, it is preferable that it is 1300-1600 degreeC, and it is more preferable that it is 1400-1600 degreeC. In particular, when the melting temperature is 1440 to 1460 ° C., the number of pores tends to be large.

  As a temperature rising rate which raises temperature to melting temperature, 100 degrees C / hour or less is preferable, and 50 degrees C / hour or less is more preferable. When the heating rate is increased, the number of pores tends to be reduced. As a lower limit of a temperature rising rate, 10 degrees C / hour or more is preferable.

  The melting time is preferably less than 2 hours, more preferably 1 hour or more and less than 2 hours. When the melting time is long, pores adjacent to each other tend to aggregate, and the number of pores tends to decrease.

  Next, in step S2, a melt obtained by melting the glass ceramic material is poured into a mold, and this is cooled and processed into a block shape to obtain a glass block in a glass state. When pouring the melt of the glass ceramic raw material into the mold, it is preferable to pour it without pressure. Thus, the glass block and the mold can be prevented from adhering to each other after cooling, and the glass block can be manufactured in a short time.

  For example, stainless steel (SUS), carbon and the like can be mentioned as a component material of the type into which the melt of the glass ceramic raw material is poured, but it is not limited thereto. The cooling may be performed to the heating temperature of the annealing process described below.

  Next, in step S3, the obtained glass block is annealed (heat treatment) to take strain. As the conditions of the annealing treatment, it is preferable to set the heating temperature to a temperature 5 to 15 ° C. lower than the glass transition temperature (Tg) and to set the heating time to 30 minutes to 2 hours, but it is not limited thereto. The glass block after the annealing treatment may be cooled to room temperature (23 ° C.). The annealing process can be omitted. When the annealing process is omitted, the cooling in step S2 may be cooled to room temperature.

  Next, in step S4, the glass block is subjected to a first heat treatment to form crystal nuclei or to grow crystals, thereby obtaining a glass block made of glass ceramics in a semi-crystallized state. As a condition of the first heat treatment, the heat treatment temperature is preferably set to 700 to 1050.degree. The heat treatment time is preferably 10 minutes to 4 hours.

  It is preferable to attach a chucking fitting to the glass block. According to such a configuration, it is possible to grind the glass block in a state in which the metal fitting is chucked to the grinding device. Attachment of the metal fitting can be performed, for example, via an adhesive or the like.

  Next, in step S5, a glass block made of glass ceramics in a semi-crystallized state is ground into the shape of a dental prosthesis to obtain a ground workpiece. Since the glass block to be ground is made of glass ceramics in a semi-crystallized state, cracks do not easily develop like glass which is not crystallized even by grinding, and therefore, it is difficult to break during grinding. In addition, since the glass block made of the glass ceramic in the semi-crystallized state is excellent in the grindability as described above, the load applied to the grinding apparatus is small, and the grinding process can be efficiently performed in a short time. As a grinding apparatus, although milling machines, such as a ball end mill, etc. are mentioned, for example, it is not limited to this.

  Next, in step S6, a second heat treatment is performed on the ground work product, and the semi-crystallized glass ceramic is crystallized to obtain a dental prosthesis. The obtained dental prosthesis has excellent strength, so it is hard to break even when chewing a hard thing.

  As a condition of the second heat treatment, it is preferable to set the heat treatment temperature to 850 to 1200 ° C. The heat treatment time is not particularly limited. The second heat treatment is preferably performed under reduced pressure.

  Finally, in step S7, a colored glass paste called porcelain for adjusting the color is applied to the dental prosthesis and baked. As an application means, a brush etc. are mentioned, for example. The baking is preferably performed at a temperature lower than the heat treatment temperature of the second heat treatment. Baking is preferably performed under reduced pressure. The dental prosthesis baked with porcelain can be used, for example, adhesively bonded to the teeth.

  As mentioned above, although the glass block for dental prostheses was demonstrated as an example as one embodiment of the present invention, the use of the glass block of the present invention is not restricted to this, and various glass ceramics formed by grinding processing It can be used as a material of a member.

  EXAMPLES Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the following examples.

<Preparation of glass block>
As glass ceramic raw materials, SiO ₂ , Al ₂ O ₃ , Li ₂ CO ₃ , ZrO ₂ , ZrO ₂ , P ₂ O ₅ , CeO ₂ , MgO, ZnO, V ₂ O ₅ , Fe ₂ O ₃ , K ₂ CO ₃ , TiO ₂ It was used. All of these glass ceramic materials are in powder form.

  The glass ceramic raw materials mentioned above were mixed so that it might become the composition of the glass ceramics shown in Table 1. The composition of the glass ceramic shown in Table 1 is a value measured by ICP emission spectrometry.

  Next, the mixed glass ceramic raw material was melted in a platinum crucible in the atmosphere under the melting conditions (melting temperature, melting time and heating rate) shown in Table 1. Then, a melt obtained by melting the glass ceramic raw material was poured into a mold made of SUS without pressure, cooled, and processed into a block shape to obtain a glass block in a glass state.

  Next, the obtained glass block was annealed. The annealing conditions were such that the heating temperature was 10 ° C. lower than the glass transition temperature (Tg), and the heating time was 1 hour. The glass block after the annealing treatment was cooled to room temperature (23 ° C.).

  Finally, the glass block was subjected to the first heat treatment, and sample No. 1 shown in Table 1 was subjected to. 1 to 11 glass blocks were obtained. The conditions for the first heat treatment were a heat treatment temperature of 700 ° C. and a heat treatment time of 30 minutes.

Sample No. Each of the glass blocks 1 to 11 was a rectangular solid having a length of 12 mm, a width of 14 mm, and a height of 18 mm. Also, for sample no. The crystallinity of the glass blocks 1 to 11 was calculated by the Rietveld analysis program "RIETAN" using X-ray diffraction data measured with an X-ray diffractometer "X'PertPRO" manufactured by PANalytical. Cr ₂ O ₃ was used as the internal standard substance. As a result, sample no. Each of the glass blocks 1 to 11 had a crystallinity of 30 to 60%. Therefore, sample no. All of the glass blocks 1 to 11 were made of semi-crystallized glass ceramics.

<Evaluation>
Sample No. The number of pores having a diameter of 0.1 to 0.5 μm, the grinding time and the grindability were evaluated for glass blocks 1 to 11. Each evaluation method is shown below, and the result is shown in Table 1.

(Number of pores with a diameter of 0.1 to 0.5 μm)
First, the glass block was broken in a mortar and the fractured surface was observed with an electron microscope at a magnification of 10,000. Next, the maximum diameter of each of the plurality of pores exposed to the fracture surface was measured, and the number of pores having a maximum diameter of 0.1 to 0.5 μm was counted among the plurality of pores. At this time, the number of pores was counted in the range of 20 μm × 20 μm. And the number of pores per unit square mm was calculated from the number of pores counted. The results are shown in the column "Number of pores (number / mm ² )" in Table 1.

  Sample No. The electron micrograph which expanded the pore of 1 to FIG. The electron micrograph which expanded the pore of 2 is each shown in FIG.2 (b). As apparent from FIG. In any of the glass blocks 1 and 2, no pores having a maximum diameter of greater than 0.5 μm were observed. Similarly, sample nos. No pores larger than 0.5 μm in maximum diameter were observed in 3 to 11 glass blocks.

(Grind time)
The grinding time (minutes) when grinding was performed under the following conditions was measured.
Grinding device: Water-cooled grinder "Plus MG5W" manufactured by Kucco-Koul Dental Co., Ltd.
Types of grinding wheels: Φ 2 (No. 120) and Φ 0.9 (No. 240) of wheels with electrodeposited diamond shaft
Number of rotations: 40,000 rpm
Feeding speed: 300 mm / min Machining shape: crown crown The sample with the longest grinding time was taken as 100, and the ratio of the grinding time of other samples to this sample was calculated. The grinding time (ratio) means that the smaller the value, the better the grindability.

(Grindability)
The grindability was evaluated from the results of the grinding time (ratio) described above. Evaluation criteria were set as follows.
◎: The grinding time (ratio) is a value of 65 or less.
○: The grinding time (ratio) is larger than 65 and smaller than 85.
Fair: The grinding time (ratio) is 85 or more, which is a value smaller than 90.
X: Grinding time (ratio) is a value of 90-100.
In the evaluation criteria, Δ is a range that causes no problem in practical use.

As apparent from Table 1, the sample No. 1 containing 30,000 / 30 ² or more pores having a diameter of 0.1 to 0.5 μm inside was found. All of 1-3, 5, 7, 9-11 showed the result which is excellent in agrindability. Among these samples, No. ¹ containing 35,000 to 700,000 cells / mm ² of pores. 1-3, 7 and 9-11 showed the result which is excellent by the grindability. In particular, sample No. ¹ containing 600,000 to 700,000 cells / mm ^{2 of} pores. 1 showed the result which is the most excellent in the grindability.

Claims (7)

Consists of a semi-crystalline state glass ceramics, and in cross-section, inside 30,000 pores with a diameter of 0.1 to 0.5 [mu] m / mm ² or more and Nde contains, in terms of oxide, the Si 63.8～ A glass block characterized by comprising 74.3% by mass, 3.7 to 21.8% by mass of Al and 3.0 to 14.3% by mass of Li . The glass block according to claim 1, wherein the pores are 35,000 to 700,000 pores / mm ² . Glass block according to claim 1 or 2, characterized in that it comprises 600,000～700,000 pieces / mm ² of the pores. The glass block according to any one of claims 1 to 3 , which is for a dental prosthesis. 63.8 to 74.3 mass% of Si, 3.7 to 21.8 mass% of Al, and 3.0 to 14 Li in terms of oxides under melting conditions including the following (I) and (II) : .3 Semi-crystallized glass ceramic containing a glass ceramic material contained at a ratio of 3% by mass and containing , in cross section, at least 30,000 particles / diameter ² with a diameter of 0.1 to 0.5 μm inside method of manufacturing features and to Ruga Las block that you.
(I) Melting temperature: 1300 to 1600 ° C
(II) Melting time: less than 2 hours The method for producing a glass block according to claim 5 , wherein the melting condition further comprises the following (III).
(III) Heating rate: 100 ° C / hour or less Dental prosthesis, wherein the semi-crystalline state glass ceramics to the crystalline state after grinding the shape of the dental prosthesis a glass block manufactured by the manufacturing method of a glass block according to claim 5 or 6 Method of manufacturing objects.