JP2002143184A - Method and assembly for pressure molding of dental element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of preventing the occurrence of the crack of dental elements. SOLUTION: The method and assembly for pressure molding of the dental elements including stamps 28, more particularly elements for dentures, such as inlays, onlays and dental crowns which include a process step of manufacturing a material mold of a lost wax type which is at least one of the elements to be molded, a process step of forming a casting mold 26 consisting of a refractory material 14 around the at least one material mold, a process step of heating the refractory material so as to expend the material mold thereby forming a molding cavity 20 to the material mold, a press aperture 24 and >=1 connecting paths 22 between the molding cavity and the press aperture 24 and a process step of introducing a press molding material 30 which is put into at least a state thrustable to a liquid form and is pushed into the molding cavity by a thrusting means into the press aperture 24 and in which the thrusting means has the coefficient of expansion substantially coinciding with the coefficient of expansion of the refractory material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a dental element. The invention particularly relates to the pressing of dental elements from pressable materials. Such methods are well known from practice.

[0002]

2. Description of the Related Art This well-known method is described in "Empress of the Firm Ivoclar".
In this method, a mold having a molding cavity in the form of a dental element formed therein is placed in a press oven, although used under the name "Ivoclar)". In the oven, the material to be pressed is heated, and then the pressed material is pressed into the molding cavity using a press integrated with the oven. Thereafter, the element is removed from the oven and, after cooling, the element is removed from the mold and surface treated.

[0003]

The method offers the advantage that relatively precise dental elements can be manufactured from relatively hard materials. Such elements are particularly suitable, for example, for denture elements. This known method, however, has the disadvantage that cracks are frequently formed in the mold, in the stamp of the press, and in the dental element. This is in each case a consequence of the material used (especially aluminum oxide), and furthermore to the extent that the expansion of the stamp is not possible to be absorbed by the refractory and pressed material. It is. A further disadvantage of this known method is that an oven with an integrated press is used for this purpose. This means
This means that special equipment that is relatively expensive must be purchased, but in each case only one mold is manufactured at a time. This means that a relatively long manufacturing time is required for each dental element, which is costly.

It is a first object of the present invention to provide a method of the type indicated in the preamble, which avoids and maintains the disadvantages of known methods.

[0005] Even more particularly, it is an object of the present invention to provide a method in which cracks in the parts of the equipment and materials used and in the elements to be formed are avoided.

It is a further object of the present invention to provide a method in the form described in the introduction, by means of which a dental element, in particular a pressed dental element, is produced relatively quickly. However, it is possible to use pressing means that can be used separately from the oven.

[0007]

To this end, a method according to the invention is characterized by the features according to claim 1.

Surprisingly, by using a pressing means having a press stamp introduced into the press opening, the press stamp has an expansion coefficient at least substantially less than that of the refractory material forming the mold. Although at least a part of the material is manufactured from the material, it is possible to prevent cracking. Without being bound by any theory, if the differences in the coefficients of expansion of the materials used are too large, stress will result in the refractory material, the stamped material and / or the stamp, and the stress will be particularly high in the material used. Due to the relatively low modulus of elasticity, it is not sufficiently absorbed. Said low modulus of elasticity is a dental element that is formed with sufficient accuracy and is sufficiently flat to obtain a dental element having at least a smooth surface,
It is informative. At least the mold and stamp must therefore retain their shape well, even at elevated temperatures. Stamps and molds according to the present invention should be deformed upon heating and cooling to at least a similar degree with respect to shape and with respect to deformation curves with respect to time. The advantage is therefore that no cracks occur in the molding mass during its cooling. The mold is still substantially stress free. This prevents the dental element from cracking. Cracking of the press forming material remaining in the press opening to the forming cavity and the feed path will be further prevented. Cracking in this residual material causes cracking of the dental element and must be prevented.

The stamp preferably has a coefficient of expansion approximately equal to the coefficient of expansion of the refractory material. Also, the stamp preferably has a coefficient of expansion approximately equal to the coefficient of expansion of the material of the cuvette in which the mold is formed.

[0010] In an advantageous embodiment, the stamp is manufactured at least in part from a material similar to, and preferably the same as, the refractory material from which the mold is manufactured. This applies in particular to parts that extend into the press opening during pressing. Stresses in other parts are thereby further prevented.

In a further detailed description, the method according to the invention is further characterized by the features according to claim 3.

The use of a cuvette made of a substantially non-oxidizing material offers the advantage that cracking in the refractory material of the mold and thus cracking in the dental element is even more possible. This is because the cuvette appropriately supports according to a change in the volume inside the cuvette. In that regard, such cuvettes are useful for use in further well-known methods.

As a material for the cuvette, a nickel-chromium alloy is particularly suitable. Also, in a further detailed description, the method according to the invention is further characterized by the features according to claim 5.

[0014] The use of compression means inside the cuvette means that the refractory material during heating or dimensional change of the mold and the expansion of the cuvette during heating and cooling,
It offers the advantage that it can be absorbed by the compression means without the occurrence of undesired pressures and stresses in the mold and / or cuvette. In that respect,
Such compressed materials are also beneficial for use in well-known methods.

As the pressure molding material, a material containing at least glass and at least a glass-like component, such as quartz, is preferably used. This allows for the liquid phase of the pressed material and is beneficial for pressing the pressed material mass into the forming cavity. In particular, a press-formed mass containing the above-mentioned glass component and ceramic component is used. A dental element is thereby obtained, which can be formed particularly precisely by its pressing properties, and furthermore obtain the desired properties for use as a denture element.

In a particularly advantageous embodiment, the method according to the invention is further characterized by the features according to claim 13.

Such a method offers the advantage that at least a part of the stamp, in particular a part extending into the press opening of the mold, is removable together with the mold from the pressing means and remains in the press opening. Typically, the mold is cut from around the dental element after sufficient hardness has been obtained. For this purpose, for example, a blasting technique is used.

In the prior art, an aluminum oxide stamp is used, which is cleaned after each use. To that end, blasting techniques are further used, in which the stamp, in particular its diameter, continuously decreases, and upon repeated use the pressed mass escapes into the gap formed between the mold and the stamp. . As a result, the quality of dental elements manufactured in a known manner is adversely affected, while the stamps become increasingly difficult to clean.
In stamps according to the present invention, this problem does not exist. Because, as a rule, all stamps are 1
This is because it is used only once and fits accurately into the press opening. Therefore, there is no problem due to wear.
Also, as a result, the desired pressure and thus the complete filling of the molding cavity is always achieved. The mold and each part of the stamp are removed together.

In a further detailed description, the method according to the invention is further characterized by the features according to claim 14.

The method described above offers the advantage that the mold can be prepared and cleared separately from the oven, while also including the oven used for another purpose, separately from the pressing means. Gives the benefit of allowing the use of a simple oven.

[0021] The invention further relates to a pressure-formed dental element assembly, characterized by the features according to claim 15.

Such an assembly has the advantage that in a relatively quick and simple manner it is possible to press-mold a dental element, at least partly of which is made of ceramic, by relatively simple means. give. Although the use of pressing means integrated with the oven is possible, the assembly preferably includes pressing means separate from the oven.

The present invention provides a cuvette for use in pressing dental elements, characterized by the features according to claim 22, and a material which is substantially non-oxidizing at the temperature required for melting the ceramic material, in particular Use of a cuvette manufactured from a nickel-chromium alloy, wherein the cuvette press-molds a dental element using ceramic in at least a part thereof in a mold manufactured from a refractory mass. About.

[0024] Further advantageous embodiments of the method and the assembly according to the invention are described in the dependent claims hereinafter.

[0025]

DETAILED DESCRIPTION OF THE INVENTION For clarity of the invention, an exemplary embodiment of the method and assembly according to the invention will be described.
It will be described with reference to the accompanying figures.

In this description, the same or corresponding parts have the same or corresponding reference numbers.

FIG. 1 shows a mold 1 in a perspective view, the mold 1 comprising three molded cavity forming parts 2, a substantially cylindrical connecting part 4 and three connecting path forming parts 8. The connection path forming portion extends in a radial direction from a point close to the first end 6 of the connection portion 4, and connects the molded cavity forming portion 2 to the connection portion 4. Each molded cavity forming part 2 has the shape of a dental element to be formed, in particular, the shape of a denture element such as an inlay, an onlay or a crown. The molding cavity forming part 2 is provided with a cavity 10 on the side remote from the connection part 4, and the denture element formed by the cavity 10 is mounted in the oral cavity. Since the mold 1 is made of a material having a relatively low melting point, such as a wax, the material can be easily removed after the mold has been formed around the mold 1, This is as described below.

The mold 1 is placed on a substrate (not shown), after which a cuvette 12 is placed over the mold 1 on the same substrate, as described in more detail below. After that, the space around the mold 1 inside the cuvette is filled with the refractory material 14 through the opening 56 in the bottom 54.
Is filled with A piece of paper 1 on the inner surface of the cuvette 12
6 is fixed as a compression means between the wall 18 of the cuvette 12 and the refractory material 14 and functions as an expansion joint. Next, the cuvette is allowed to reach a certain temperature for a certain period of time.
It is preheated so that substantially no more gas escapes from the refractory mass, while the mold 1 flows out.
The refractory mass 14 is thereby hardened while the mold 2
In the refractory material 14 functioning as 6, a molding cavity 20 having the shape of the molding cavity forming part 2 is formed, together with a connecting pipe 22 formed by the connecting pipe forming part 8 and a press opening 24 formed by the connecting part 4. , Obviously left.

Subsequently, the cuvette 12 with the mold 26 is turned over to the position shown in FIG. An appropriate amount of the press forming material is supplied into the press opening 24, for example, in the form of a pellet, and then the stamp 28 contacts the upper part of the press forming material 30 and moves into the press opening 24. The stamp 28 is arranged such that the outer wall of the stamp 28 is placed substantially in contact with the wall of the press opening 24.
It corresponds to the outer circumference of the connection 4 and thus the press opening 2
4 has an outer circumference coinciding with the inner circumference. The stamp 28 is made from a material having a coefficient of expansion that substantially matches the coefficient of expansion of the refractory material 14, so that there is substantially no stress during heating and cooling. In the embodiment shown, the stamp 28 is made from the same material as the refractory mass 14, at least a similar material. The length of the stamp 28 preferably corresponds at least approximately to the depth of the press opening 24.

After the stamp 28 has been placed on the compact 30, the cuvette 12 with the mold 26, the stamp 28 and the compact 30 are heated to the processing temperature of the compact 30. You. This means that the heating is obtained such that the pressed mass 30 is easily pressed through the connecting channel 22 into the molding cavity 20 and is completely filled.

When sufficient heating is obtained, the cuvette 12
Is arranged on the press table 32 of the press 34 and below the press arm 36, as schematically shown in FIG. Stamp 28 then extends above upper surface 38 of refractory material 14. The press arm 36 is pivotally connected to a support column 44 via a shaft 42.
Connected to 0. The lever 40 is connected to a piston rod 46 of a piston-cylinder assembly 48 on a side of the column 44 remote from the press arm 36, and the piston-cylinder assembly 48, like the column 44 and the press table 32, has a press It is connected to the base 50. Since, for example, compressed air can be introduced through the opening 51 of the cylinder 52 of the piston-cylinder assembly 48, the lever 40 can be tilted by the piston rod 46 and the stamp 28 can be pressed by the press arm 36. It is possible to press into the opening 24, thereby moving the pressure-formed mass 30.
As mentioned earlier, the pressed mass 30 is pressed through the connecting passage 22 and into the forming cavity 20 to form the desired dental element. After pressing, the pressure of the piston-cylinder assembly can be removed, the press arm can be raised to its original position, and then the cuvette 12 can be removed from the press table 32. .

After the mold 26 and the press molding material 30 have been sufficiently cooled, the mold 26 is removed from the cuvette 12 by, for example, pushing the mold 26 through an opening 56 formed in the bottom 54 of the cuvette 12. You. The cuvette 12 has a slightly conical interior and a bottom 54
Clearing is easy because a taper is provided outward in the direction away from the center. After the mold has been removed from the cuvette, the refractory material 14 includes a stamp 28 and is formed around the cured press-molded material 30, i.e., within the dental element 20 and the connection channel 22 and the press opening 24. The refractory material 14 around the portion is cut or otherwise removed, for example by blasting, using a technique appropriate for that purpose. After this, the dental elements are removed and surface treated, for example by sawing them off.

The cuvette 12 includes a first slot 58 on both sides of an opening 56 in the bottom 54 thereof.
(FIG. 2) and a cuvette fork, known per se, enters the cuvette to remove the cuvette 12. Further, the wall portion 18 is provided with a second slot 60 which opens laterally on both sides of the cuvette 12, and the second slot 60 further contains a cuvette tong for operating the cuvette 12, which is known per se. Put in. The stamp 28 is provided with a chamfered end on the side extending to the press opening 24 during use, and
This is done in order to optimally apply pressure to zero, so that the material is even better pushed into the molding cavity.

The refractory material from which the mold is made preferably uses a material which has a relatively high weight percentage of filler and is held together by the binder. As filler, for example, quartz, aluminum oxide and the like, or mixtures thereof, are used, and the stamps are preferably manufactured from the same material. In this regard, the binder may be, for example, MgO NH ₄ H ₂ PO
₄ is used. The refractory material is, for example, 60
Consists of weight percent to 85 weight percent filler and 15 weight percent to 40 weight percent binder. Preferably, no less than 70 weight percent and no more than 80 weight percent of filler is used, the remainder being supplemented with binder to 100 percent. The refractory material is degassed prior to filling the mold to prevent undesired chemical reactions such as oxidation and to obtain sufficient density.

As the pressure-molded ingot, a material having sufficient fluidity at an increase in temperature to be pressed into the cavity is preferably used. On the other hand, after cooling, a hard and smooth ingot is formed. The mass still allows for surface treatments such as polishing and coloring. Thus, for example, it comprises from 40% to 85% by weight, preferably from 50% to 70% by weight, of SiO ₂ and many other components, such as Al ₂ O ₃ , K ₂ O, Na ₂ O, Li ₂ O, BaO, Ca
A press-molded material mass is used to make up the remainder with a mixture of O, Ba ₂ O ₃ , F ₂ , P ₂ O _{5 and the} like. It would be particularly advantageous to use a pressed mass that substantially contains silicate glass having at least that property.

As will be clear from the present description, in the method according to the invention, the stamp is, for example, manufactured in such a way that it is at least partially used, in principle, only once and erased with the mold. Thus, wear problems do not occur and costly cleaning operations are omitted. In the embodiment shown, the stamp is designed in bulk. However, it is clear that the stamp may be designed hollow, and thus with appropriate compatibility,
The stamp can be provided at the free end of the press arm. The degree of filling of the molding cavities may be determined, for example, based on the displacement of the stamp, so that in each case it is possible to obtain a suitable filling indentation pressure.

[0037] Such press stamps can also be used in integrated press ovens of a further known type. Since the press opening is partitioned by the stamp, any pressing direction can be selected. In principle, it is also possible for the cuvette to be arranged in the pressing device with its bottom side-to-side or bottom-up.

The present invention is not limited in any way to the exemplary embodiments shown in the description and figures. Many of these variations are possible within the scope of the invention as outlined by the claims.

Therefore, for example, another type of press may be used, for example, a type in which the piston-cylinder assembly is directly connected to the press arm, or a type in which an eccentric pressing mechanism or the like is used. Good. It is also possible to use a manual pressing means such as an appropriate tongue. Furthermore, it is possible to use other compositions of the press-molding material and / or the refractory mass, as long as the press-forming material can be pressed into the molding cavity by the above-mentioned pressing means. A different number of molding cavities may be provided in the mold, which may be otherwise connected to the press opening by a composite stamp,
For example, it may be connected to several press openings provided for different molding cavities. If the refractory mass has sufficient inherent strength to absorb the development of internal pressure, the mold can be used without a cuvette. Obviously, the cuvette may be designed differently, for example according to the elements to be formed. Also, the dental component may be designed differently, for example provided with another fixing means, which may be included in the mold, for example as an insert, so that the fixing means , At least a portion of which will be surrounded by the pressure molding material.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a brazing mold with connections of three dental elements.

FIG. 2 is a cut-away side view showing a cuvette provided with a molding cavity and a part of a pressing means.

3 is a partial cut-away side view schematically illustrating a press with a cuvette according to FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Material type 2 Molding cavity formation part 4 Connection part 6 1st end part 8 Connection path formation part 10 cavity

 ──────────────────────────────────────────────────続 き Continued on the front page (71) Applicant 500492015 Verlende Lageweg 10, HOORN, NETHERLANDS

Claims (23)

[Claims] 1. A method for pressure-forming a dental element, in particular a denture element, comprising the step of producing at least one mold of the element to be molded, the mold being of a vanishing type. Creating a mold of refractory material around one mold, heating the refractory material to dissipate the mold, thereby forming a cavity for the mold, a press opening, Forming one or more connection paths between the molding cavity and the press opening; and forming a pressurized molding material which is in a liquid state, at least pressurizable, and which is pressed into the molding cavity by pressing means. Introducing said press opening into said press opening, wherein said pressing means comprises a stamp having a coefficient of expansion substantially corresponding to the coefficient of expansion of the refractory material, for pressure molding the dental element. the method of 2. The stamp according to claim 1, wherein at least a portion thereof extends into the press opening during pressing, and the stamp is formed from, preferably the same as, the refractory mass in which the mold is formed. The method of claim 1, wherein: 3. The refractory mass for the mold is introduced into a cuvette, the cuvette being made of a substantially non-oxidizing material, in particular a metal.
Or the method of 2. 4. The method of claim 3, wherein the ingot is introduced into a cuvette made of a nickel chromium alloy or an alloy having similar resistance to oxidation at elevated temperatures. 5. The mold is formed in a cuvette and, prior to introducing the refractory material into the cuvette, is provided with compression means, the means for compressing while heating and pressing the pressed mass. A method according to any of the preceding claims, characterized in that it is able to do so and thus functions as an expansion joint. 6. The cuvette according to claim 1, wherein
The method of claim 5, wherein a compacted material such as a piece of paper is disposed. 7. A method according to any preceding claim, wherein the mold is formed in a cuvette that tapers slightly inward in the direction of the bottom. 8. The method as claimed in claim 1, wherein the pressure-forming material is a mass of glass, in particular silicate glass. 9. The method as claimed in claim 1, wherein the pressure-forming material is a mass at least partially composed of a ceramic material. 10. The press-molded material of from 40% to 85% by weight, in particular from 50% to 75% by weight, preferably from 50% to 75% by weight.
Not less than 70% by weight of SiO ₂
The method according to claim 8, wherein a mass containing the following is used. 11. Refractory masses of from 60 to 85% by weight, in particular from 70 to 8% by weight.
0% by weight of fillers such as quartz and aluminum oxide and 15% to 40% by weight, in particular 20% to 30% by weight of M
The method according to any one of the preceding claims, characterized in that the wood mass containing a binder such as gO NH ₄ H ₂ PO ₄ is used. 12. The method according to claim 1, wherein the refractory mass is degassed and densified before introducing the pressure molding material. 13. When the mold is removed from the pressing means after the pressing of the pressed molding material, at least a part of the stamp remains in the mold, in particular in the press opening, and the at least one dental element is removed from the mold. A method according to any of the preceding claims, wherein said method is substantially eliminated when said method is applied. 14. The preceding claim, wherein an oven is used at least for heating the mold, the mold is placed in the oven, and a press is used for pressing separately from the oven. The method of any of the preceding clauses. 15. An assembly for pressing a dental element, comprising a pressing means, a cuvette, and a refractory material for forming a mold in the cuvette, forming a mold of the dental element to be formed. It is provided that a fugitive, in particular brazing, modeling means is provided, said pressing means comprising at least a stamp made of a material having an expansion coefficient substantially matching that of the refractory material. Assembly features. 16. The assembly according to claim 15, wherein the stamp is at least partially manufactured from the same material as the refractory mass. 17. The cuvette according to claim 15, wherein the cuvette is made by a clearing design so as to taper inward, in particular in the direction of the bottom.
The described assembly. 18. The stamp according to claim 15, wherein at least part of the stamp is made from a refractory mass.
An assembly according to any of claims 17 to 17. 19. The assembly according to claim 15, wherein the cuvette is made of a substantially non-oxidizing material, in particular a nickel chromium alloy. 20. The apparatus according to claim 15, further comprising a compression means disposed between the wall portion of the cuvette and the refractory mass when the cuvette is used.
20. The assembly according to any of 19. 21. The assembly of claim 20, wherein the stamp is designed such that at least a portion thereof is lost with the refractory material when removing the dental element from a mold. 22. A cuvette used in pressing a dental element from a ceramic material, wherein the cuvette is made of a substantially non-oxidizing material at a temperature required for melting the ceramic material, in particular a nickel chromium alloy. A cuvette characterized by being performed. 23. Use of a cuvette made of a substantially non-oxidizing material, especially a nickel chromium alloy at the temperature required for melting of the ceramic material, in a mold made of a refractory material in the cuvette. The use of a cuvette for pressing at least partly a ceramic dental element.