JP4870038B2 - Dental processing block - Google Patents

Description

  The present invention relates to a dental processing block for cutting out a frame material.

  In recent years, materials that replace metals are being used for frame materials such as crown or inlay restorations used for dental treatment, for the purpose of preventing black margins, patients with metal allergies, or high aesthetics. A typical material as a metal substitute material is resin or ceramics. For example, when producing a frame material made of ceramics, precision cutting / grinding using a CAD / CAM device is performed on a ceramic block. Such a dental processing block is disclosed in Patent Document 1.

  Since the frame material (dental prosthesis) that is directly involved in mastication must be able to withstand pressure or impact during mastication, high-strength ceramics are suitable for the dental processing block. Used for. In particular, in the case of a bridge that connects teeth on both sides of a missing tooth, it is necessary to withstand the force applied to the missing part, and therefore it is required to use ceramic with higher strength.

  There are the following three types of conventional ceramic frame materials. The first frame material is subjected to cutting / grinding processing that is necessary for the patient on the temporarily sintered block, and then completely sintered. The second frame material is for producing a completely sintered block, and cutting and grinding the block into a shape necessary for the patient. The third frame material is formed by depositing metal oxide powder in a shape necessary for a patient and pre-sintering, and then spraying glass powder on the surface to melt and impregnate the glass.

JP 2001-19539 A (abstract, etc.)

  In the case of the first frame material described above, the block in the pre-sintered state is a choke-like material, so that it is easy to process. However, since it is completely sintered after cutting and grinding, it is necessary to predict the amount of shrinkage after sintering and perform cutting and grinding, and it is difficult to obtain a target shape. Further, in the case of the second frame material, since the cutting and grinding are performed after being completely sintered, the processing takes a long time and the deterioration of the grinding tool or the like is rapid. In the case of the third frame material, since the bending strength is as low as about 500 MPa, it cannot be applied to a bridge having a large number of teeth.

  Accordingly, an object of the present invention is to provide a dental processing block for manufacturing a frame material having bending strength that is easy to cut and grind after complete sintering and can be applied to a bridge having a plurality of tooth defects. And

  To achieve the above object, a dental processing block according to the present invention comprises 100 parts by mass of a metal oxide mainly composed of at least one of zirconia, alumina, mullite and spinel, lanthanum phosphate and / or aluminum phosphate 1 It is assumed to include at least 23 parts by mass.

  In the dental processing block of the present invention, lanthanum phosphate and / or aluminum phosphate is contained in a metal oxide mainly containing at least one of zirconia, alumina, mullite and spinel, so that the bending strength of the metal oxide is obtained. Decreases. Therefore, by making the content of lanthanum phosphate and / or aluminum phosphate 1 part by mass or more and 23 parts by mass or less with respect to 100 parts by mass of the metal oxide, cutting / grinding is facilitated and multiple teeth It is possible to have a bending strength applicable also to a bridge of a defect.

  In another dental processing block according to the present invention, in addition to the above-described invention, lanthanum phosphate and / or aluminum phosphate is present as a crystal. By adopting this configuration, cutting / grinding becomes easier.

  In another dental processing block according to the present invention, in addition to the above-mentioned invention, the average particle diameter of the lanthanum phosphate and / or aluminum phosphate crystal is 0.01 μm or more and 1 μm or less. By using lanthanum phosphate and / or aluminum phosphate having such an average particle diameter, cutting and grinding are further facilitated, and coarse lanthanum phosphate and / or aluminum phosphate crystals are destroyed. It becomes difficult to become a starting point and the strength is improved.

  According to the present invention, it is possible to manufacture a frame material having bending strength that is easy to cut and grind after complete sintering and can be applied to a bridge having a plurality of tooth defects.

  A dental processing block according to an embodiment of the present invention will be described below.

The dental processing block according to the embodiment of the present invention includes at least one of zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), mullite (3Al ₂ O ₃ .2SiO ₂ ), and spinel (MgAl ₂ O ₄ ). It contains 100 parts by mass of a metal oxide as a main material and 1 to 23 parts by mass of lanthanum phosphate and / or aluminum phosphate. Hereinafter, the metal oxide, lanthanum phosphate / aluminum phosphate, and manufacturing method used for manufacturing the dental processing block will be described.

(1. Metal oxide)
The metal oxide raw material powder is preferably at least one of zirconia powder, alumina powder, mullite powder, and spinel powder and having an average particle size of 0.01 to 50 μm. More preferably, a raw material powder having an average particle size of 0.03 to 20 μm is used. When the average particle size is larger than 0.01 μm, the handling is easy and the phase transformation of the oxide crystal is difficult to occur. Further, when the average particle size is smaller than 50 μm, large crystal grains are hardly generated by sintering, and the strength can be improved.

  Zirconia powder may have a monoclinic crystal, tetragonal crystal, cubic crystal, or a mixed crystal of one or more of these, but includes a stabilizer such as yttria, calcia, magnesia, ceria, and the like. And partially stabilized zirconia consisting of monoclinic crystals are suitable for use. The alumina powder may have any crystal structure such as γ, δ, κ, θ, η, α type, etc., but easily available γ-alumina or α-alumina powder is preferable. The mullite powder may contain corundum crystals or glassy material, but is preferably composed of almost 100% mullite crystals. The spinel powder may contain alumina or magnesia, but preferably does not contain these.

(2. Lanthanum phosphate / Aluminum phosphate)
As the raw material powder of lanthanum phosphate or aluminum phosphate, one having an average particle diameter of 0.01 to 1 μm, preferably 0.03 to 0.6 μm is used. When a powder having an average particle size of 0.01 μm or more is used, the cutting / grindability of the dental processing block is improved. On the other hand, when a powder having an average particle size of 1 μm or less is used, coarse particles are hardly generated by sintering, and the strength can be improved.

  Content of a lanthanum phosphate and / or aluminum phosphate is 1-23 mass parts with respect to 100 mass parts of metal oxides, Preferably it is 5-22 mass parts. When the content of lanthanum phosphate and / or aluminum phosphate is 1 part by mass or more, the cutting / grindability of the dental processing block is improved. On the other hand, when the content is 23 parts by mass or less, the strength of the dental processing block is improved. Therefore, considering the balance between easy cutting / grindability and high strength, it is appropriate that the content of lanthanum phosphate and / or aluminum phosphate is 1 to 23 parts by mass.

  The above lanthanum phosphate and / or aluminum phosphate can be easily produced as a precipitate by mixing an aqueous solution of a lanthanum salt and / or an aluminum salt and an aqueous solution of a phosphate. Although this precipitation occurs instantaneously, it may be aged for several hours. Lanthanum phosphate and / or aluminum phosphate may be either a method using pulverization or a method using precipitation, but it is preferable because it is easier to precipitate.

  As the above lanthanum salt, lanthanum nitrate, lanthanum chloride, lanthanum bromide, lanthanum bromate, lanthanum chlorate, lanthanum iodide, and the like can be used. Among these, lanthanum nitrate is preferably used. Moreover, as the above-mentioned aluminum salt, aluminum nitrate, aluminum chloride, aluminum bromide, aluminum bromate, aluminum chlorate, aluminum iodide and the like can be used, and among these, aluminum nitrate is preferably used. These lanthanum salts or aluminum salts may be a mixture of two or more of those exemplified above.

  As the above-mentioned phosphates, orthophosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate Other soluble phosphates can be used, and among these, orthophosphoric acid is preferably used. The phosphate may be a mixture of two or more of those exemplified above.

  The mixing ratio of the above-mentioned lanthanum salt and / or aluminum salt and the above-mentioned phosphate is such that the molar ratio of lanthanum salt and / or aluminum salt to phosphate is 0.8 to 1.2. Is preferred. Incidentally, a metal oxide powder is previously present in an aqueous solution of lanthanum salt and / or aluminum salt and an aqueous solution of phosphate, and mixed powder of lanthanum phosphate and / or aluminum phosphate powder and metal oxide powder. May be produced.

(3. Manufacturing method of dental processing block)
When mixing 100 parts by mass of the metal oxide powder and 23 parts by mass of the powder of lanthanum phosphate and / or aluminum phosphate, in the case of dry mixing, a vibration mill, a rotary mill, or a barrel mill is preferably used. On the other hand, in the case of wet mixing, a magnetic stirrer, mixing using a stirring blade, ball mill mixing, or the like is preferably used. As a molding method, a die press, extrusion molding, injection molding, cold isostatic pressing (CIP) or the like is preferably used. Since lanthanum phosphate and / or aluminum phosphate has a function as a binding aid (binder) at the time of molding, it can be molded without requiring any special binder. For sintering, methods such as atmospheric pressure sintering, gas pressure sintering, hot isostatic pressing (HIP) can be employed. The sintering temperature can be selected appropriately depending on the type of metal oxide, the type of lanthanum phosphate and / or aluminum phosphate and the amount added, preferably 700 ° C. to 1400 ° C. An appropriate temperature within the temperature range is preferable. Lanthanum phosphate and / or aluminum phosphate acts as a sintering aid during sintering. For this reason, the relative density of the sintered body can be densified to 97% or more in atmospheric pressure sintering without adding any other special auxiliary agent. In addition, in order for lanthanum phosphate and / or aluminum phosphate to be present as crystals in the dental processing block, it is preferable to set the sintering temperature high.

(Main effects of this embodiment)
The dental processing block according to the present embodiment can produce a frame material that is easy to cut and grind after complete sintering and has bending strength (600 MPa or more) that can be applied to a bridge having many tooth defects. Block. The ease of cutting and grinding after complete sintering is thought to be due to the cleavage of lanthanum phosphate and aluminum phosphate contained in the dental processing block. Here, “cleavage” is a property in which a crystal or the like is cracked or peeled along a specific direction or a specific surface. Similarly, cleaving substances include mica and the like, but mica is easily affected by acid in the oral cavity and eluted. On the other hand, lanthanum phosphate and aluminum phosphate are excellent in acid resistance and have low biological harm. For this reason, lanthanum phosphate and / or aluminum phosphate are suitable as additives for dental processing blocks. Zirconia, alumina, mullite, and spinel are also suitable as main materials for dental processing blocks because of their low biological harm.

  When a part or all of lanthanum phosphate and / or aluminum phosphate is present as a crystal in the dental processing block, cutting / grinding is easier than existing as an amorphous material. This is considered due to the cleavage of the crystal. The average particle size of the lanthanum phosphate and / or aluminum phosphate crystals present in the dental processing block is usually 0.01 to 1 μm, preferably 0, derived from the average particle size of the raw material powder. 0.03 to 0.6 μm. That is, the dental processing block of the present invention has a cutting / grinding property of the dental processing block when the lanthanum phosphate and / or the aluminum phosphate crystal is contained as an average particle diameter in such a range. Is particularly favorable.

  Examples of dental processing blocks will be described below. However, the present invention is not limited to the following examples. In Examples and Comparative Examples, various physical properties were measured according to the following methods.

(1) X-ray analysis The X-ray diffraction of the sintered compact was measured using the X-ray-diffraction apparatus "RINT-1200" (made by Rigaku Corporation), and the crystal | crystallization in a sintered compact was identified.

(2) Average particle diameter and content of lanthanum phosphate or aluminum phosphate crystal Lanthanum phosphate using a scanning electron microscope “S-3400N” (manufactured by Hitachi High-Technologies Corporation) (hereinafter abbreviated as “SEM”) And / or the average particle diameter of the aluminum phosphate crystal and its content were calculated.
For the average particle diameter, an average value of 100 crystal particles randomly extracted on the SEM observation screen was calculated.
The content was calculated from the occupancy area and density of lanthanum phosphate and / or lanthanum phosphate on the SEM observation screen, and determined as a part by mass with respect to 100 parts by mass of zirconia.
In addition, in the SEM observation screen of the dental processing block, confirmation of each crystal of lanthanum phosphate and aluminum phosphate was performed by using a composition display in a backscattered electron image.

(3) Density The volume of the sintered body was calculated from the diameter and thickness. The sintered body was weighed, and the density was calculated from the mass and volume. The sintered density was calculated from the density (6 g / cm ³ ) of the zirconia powder “TZ-3Y-E” (trade name, manufactured by Tosoh Corporation) and the calculated density.
Density = Mass of sintered body / Volume of sintered body Relative density = density of sintered body / (density of lanthanum phosphate × mixing ratio + density of aluminum phosphate × mixing ratio + density of “TZ-3Y-E” × Mixing ratio)

(4) Bending strength A three-point bending strength test was performed on the sintered body. The test sample is obtained by grinding and polishing the obtained sintered body to have a thickness of 1.2 mm, a width of 4 mm, and a length of 25 mm. The surface of 4 mm in width is brought into contact with two rod-shaped supports (the radius of curvature of the portion in contact with the sample is 0.8 mm) arranged in parallel so that the distance between the fulcrums is 15 mm. Placed on. Then, the crosshead (the radius of curvature of the portion in contact with the sample was 0.8 mm) was pressed against one central point between the fulcrums (one central point of the sample) at a speed of 0.5 mm / min until the sample was broken. And the maximum stress until a sample broke was measured (n = 4).

(5) Machinability Using Diamond Point HP Form 25 (made by Matsukaze), grinding was performed at 10000 rpm (ULTIMATE 500 (made by Nakanishi) under water cooling perpendicularly to the side surface of the sintered body, and the grinding depth after 5 seconds was measured. .

Example 1
Lanthanum nitrate hexahydrate (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 27.8 g and distilled water 300 g (reagent manufactured by Wako Pure Chemical Industries, Ltd.) were weighed and mixed to obtain a lanthanum nitrate aqueous solution. Further, 7.8 g of orthophosphoric acid (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) and 300 g of distilled water (reagent manufactured by Wako Pure Chemical Industries, Ltd.) were weighed and mixed to obtain an aqueous phosphoric acid solution. An aqueous phosphoric acid solution was mixed with an aqueous lanthanum nitrate solution with stirring. Immediately after mixing, the aqueous solution became cloudy to obtain a lanthanum phosphate aqueous solution. The obtained mixture was subjected to solid-liquid separation using a centrifuge. 900 g of ethanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was added to the sediment, mixed for 1 hour, and solid-liquid separation was performed by centrifugation. After the same operation was performed twice, the precipitate was dried at 50 ° C. for 24 hours.
10.0 g of the obtained powder (average particle size 0.20 μm in SEM observation), 100 g of “TZ-3Y-E” and 300 g of distilled water are weighed and mixed for 3 hours, and solid-liquid separation is performed by centrifugation, and the precipitate Was dried at 50 ° C. for 24 hours.

  The sediment was dried at 50 ° C. for 24 hours. 1 g of the dried product was die-pressed with a diameter of 13 mm to obtain a disk-shaped green compact. Further, the dried product was die-pressed at 5 mm × 30 mm to obtain a green compact of a quadrangular column. The green compact was fired under conditions of 1250 ° C. for 2 hours using an electric furnace “Super Burn” manufactured by Motoyama Co., Ltd.

Example 2
Lanthanum nitrate hexahydrate (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 83.3 g and distilled water 900 g (reagent manufactured by Wako Pure Chemical Industries, Ltd.) were weighed and mixed to obtain a lanthanum nitrate aqueous solution. Further, orthophosphoric acid (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) 23.4 g and distilled water (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 900 g were weighed and mixed to obtain an aqueous phosphoric acid solution. An aqueous phosphoric acid solution was mixed with an aqueous lanthanum nitrate solution with stirring. Immediately after mixing, the aqueous solution became cloudy to obtain a lanthanum phosphate aqueous solution. The obtained mixture was subjected to solid-liquid separation using a centrifuge. 900 g of ethanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was added to the sediment, mixed for 1 hour, and solid-liquid separation was performed by centrifugation. After the same operation was performed twice, the precipitate was dried at 50 ° C. for 24 hours.
22.0 g of the obtained powder (0.55 μm in SEM observation), 100 g of “TZ-3Y-E” and 400 g of distilled water are weighed and mixed for 3 hours, solid-liquid separation is performed by centrifugation, and the precipitate is 50 ° C. , And dried for 24 hours.

  The sediment was dried at 50 ° C. for 24 hours. 1 g of the dried product was die-pressed with a diameter of 13 mm to obtain a disk-shaped green compact. Further, the dried product was die-pressed at 5 mm × 30 mm to obtain a green compact of a quadrangular column. The green compact was sintered under conditions of 1250 ° C. for 2 hours using an electric furnace “Super Burn” manufactured by Motoyama Co., Ltd.

Example 3
27.7 g of aluminum nitrate nonahydrate (reagent, manufactured by Wako Pure Chemical Industries) and 300 g of distilled water (reagent, manufactured by Wako Pure Chemical Industries) were weighed and mixed to obtain an aqueous aluminum nitrate solution. Moreover, 15.0 g of ammonium phosphate (reagent special grade, manufactured by Wako Pure Chemical Industries) and 300 g of distilled water (reagent, manufactured by Wako Pure Chemical Industries) were weighed and mixed to obtain an aqueous phosphoric acid solution. An aqueous phosphoric acid solution was mixed with an aqueous aluminum nitrate solution with stirring. Immediately after mixing, the aqueous solution became cloudy to obtain an aluminum phosphate aqueous solution. The obtained mixture was subjected to solid-liquid separation using a centrifuge. 600 g of ethanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was added to the precipitate, mixed for 1 hour, and solid-liquid separation was performed by centrifugation. After the same operation was performed twice, the precipitate was dried at 50 ° C. for 24 hours.

  10.0 g of the obtained powder (average particle size 0.06 μm in SEM observation), 100 g of “TZ-3Y-E” and 300 g of distilled water are weighed and mixed for 3 hours, solid-liquid separation is performed by centrifugation, and sediment Was dried at 50 ° C. for 24 hours.

  1 g of the dried product was die-pressed with a diameter of 13 mm to obtain a disk-shaped green compact. Further, the dried product was die-pressed at 5 mm × 30 mm to obtain a green compact of a quadrangular column. The green compact was sintered at 1250 ° C. for 2 hours using an electric furnace “Superburn” manufactured by Motoyama Co., Ltd.

Comparative Example 1
“TZ-3Y-E” used in Example 1 was die-pressed with a diameter of 13 mm to obtain a disk-shaped green compact. Further, the dried product was die-pressed at 5 mm × 30 mm to obtain a green compact of a quadrangular column. The green compact was fired at 1250 ° C. for 2 hours using an electric furnace “Super Burn” manufactured by Motoyama Co., Ltd.

Comparative Example 2
Lanthanum nitrate hexahydrate (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 83.3 g and distilled water 900 g (reagent manufactured by Wako Pure Chemical Industries, Ltd.) were weighed and mixed to obtain a lanthanum nitrate aqueous solution. Further, orthophosphoric acid (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) 23.4 g and distilled water (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 900 g were weighed and mixed to obtain an aqueous phosphoric acid solution. An aqueous phosphoric acid solution was mixed with an aqueous lanthanum nitrate solution with stirring. Immediately after mixing, the aqueous solution became cloudy to obtain a lanthanum phosphate aqueous solution. The obtained mixture was subjected to solid-liquid separation using a centrifuge. 900 g of ethanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was added to the sediment, mixed for 1 hour, and solid-liquid separation was performed by centrifugation. After the same operation was performed twice, the precipitate was dried at 50 ° C. for 24 hours.
27.0 g of the obtained powder (0.25 μm in SEM), 100 g of “TZ-3Y-E” and 400 g of distilled water are weighed and mixed for 3 hours, solid-liquid separation is performed by centrifugation, and the precipitate is placed at 50 ° C. It was dried under the condition of 24 hours.

  1 g of the dried product was die-pressed with a diameter of 13 mm to obtain a disk-shaped green compact. Further, the dried product was die-pressed at 5 mm × 30 mm to obtain a green compact of a quadrangular column. The green compact was sintered under conditions of 1250 ° C. for 2 hours using an electric furnace “Super Burn” manufactured by Motoyama Co., Ltd.

  Table 1 shows the X-ray analysis, particle diameter, mass part, density, bending test, and machinability of each sintered body obtained in Examples 1 to 3 and Comparative Examples 1 and 2.

As a result, peaks corresponding to lanthanum phosphate (LaPO ₄ ) and zirconia (ZrO ₂ ) were observed in the dental processing blocks obtained in Example 1, Example 2 and Comparative Example 2. In the dental processing block obtained in Example 3, peaks corresponding to aluminum phosphate (AlPO ₄ ) and zirconia (ZrO ₂ ) were observed. From this result, the dental processing blocks obtained in Example 1, Example 2 and Comparative Example 2 have lanthanum phosphate and zirconia, and the dental processing block obtained in Example 3 It was found that aluminum phosphate and zirconia were present. On the other hand, in the dental processing block obtained in Comparative Example 1, only a peak corresponding to zirconia was observed.

  With respect to the dental processing blocks obtained in Examples 1 to 3, the average particle diameter and the content of the lanthanum phosphate or aluminum phosphate crystal were measured. As a result, in the dental processing block obtained in Example 1, the average particle size of the lanthanum phosphate crystal was 0.20 μm and the content was 9.5 parts by mass. The dental processing block thus obtained had an average particle size of lanthanum phosphate crystal of 0.55 μm and a content of 21.7 parts by mass. The dental processing block obtained in Example 3 As for the block, it turned out that the average particle diameter of the crystal body of an aluminum phosphate is 0.06 micrometer, and content is 9.8 mass parts. On the other hand, the lanthanum phosphate and / or aluminum phosphate crystals were not found in the dental processing block obtained in Comparative Example 1, and the lanthanum phosphate in the dental processing block obtained in Comparative Example 2 was not observed. The average particle size and content of the crystals were 0.25 μm and 26.7 parts by mass, respectively.

The density was measured about the block for dental processing obtained in Examples 1-3. As a result, the dental processing block obtained in Example 1 has a density of 5.75 g / cm ³ and a relative density of 99%. The dental processing block obtained in Example 2 is The density is 5.60 g / cm ³ and the relative density is 98%. The dental processing block obtained in Example 3 has a density of 5.52 g / cm ³ and a relative density of 98. %. On the other hand, the density and relative density of the dental processing block obtained in Comparative Example 1 were 5.83 g / cm ³ and 98%, respectively, and the density and relative density of the dental processing block obtained in Comparative Example 2 were Were 5.43 g / cm ³ and 96%, respectively.

  In Example 1, the average value of the maximum stress (bending strength) of the four samples was 780 MPa, and the minimum value of the bending strength exceeded 750 MPa. In Example 2, the average value of the maximum stress (bending strength) of the four samples was 650 MPa, and the minimum value of the bending strength exceeded 600 MPa. In Example 3, the average value of the maximum stress (bending strength) of the four samples was 700 MPa, and the minimum value of the bending strength exceeded 650 MPa. From this result, it was found that the obtained dental processing block can produce a frame material having bending strength applicable to a bridge having a large number of tooth defects. The bending strength of the frame material that can be applied to the bridge having a large number of teeth is 600 MPa or more under the measurement conditions of this embodiment. On the other hand, the average bending strength of the sample cut out from the dental processing block obtained in Comparative Example 1 is 900 MPa, and the average bending strength of the sample cut out from the dental processing block obtained in Comparative Example 2 is It was 530 MPa.

  Further, as a result of the cutting test, the dental processing blocks obtained in Examples 1 to 3 and Comparative Example 2 had cutting depths of 0.5 mm, 0.8 mm, 0.7 mm, and 1.0 mm, respectively. There was no spark and no diamond bar was worn, and it was found that grinding was easy. From this result, it was found that the obtained dental processing block was easy to grind after complete sintering. On the other hand, the dental processing block obtained in Comparative Example 1 has a cutting depth of less than 0.1 mm, sparks are observed, and wear of the diamond bar is observed. I found out.

  The present invention has industrial applicability to a dental processing block for scraping a frame material.

Claims (3)

  Dental processing comprising 100 parts by mass of a metal oxide mainly composed of at least one of zirconia, alumina, mullite and spinel, and 1 part by mass to 23 parts by mass of lanthanum phosphate and / or aluminum phosphate For block.   2. The dental processing block according to claim 1, wherein the lanthanum phosphate and / or aluminum phosphate exists as a crystal.   The dental processing block according to claim 1 or 2, wherein an average particle size of the lanthanum phosphate and / or aluminum phosphate crystal is 0.01 µm or more and 1 µm or less.