DE102010028693A1 - Method for manufacturing denture part from three-dimensional-data i.e. CAD data, involves sintering scaffold body with outer geometry of denture part, where density of material is smaller than final density of denture part - Google Patents

Abstract

The method involves sintering a scaffold body (14) with an outer geometry of a denture part (9) made of a ceramic material (8) e.g. zirconia or aluminum oxide, by laser, where density of the material is less than final density of the manufactured denture part to attain final density by a post-treatment. The density of the scaffold body is predefined according to the laser sintering process. The scaffold body is in-filtered with a filler (13), where outer geometry of the scaffold body comprises laser sintering mass corresponding to final dimensions of the manufactured denture part.

Description

The invention relates to a method for producing a dental prosthesis part from 3D data as well as a tooth replacement part made thereafter.

State of the art

In the prior art, it is known to produce ceramic dentures from CAD data. For this purpose, a variety of different methods are proposed.

Among the best known methods is the abrasive machining of a blank by means of suitable computer-controlled processing machines.

Such a procedure is described in the WO 99/47065 disclosed. A blank is used which has not yet been sintered to final strength and from which a tooth replacement part is machined, which is densely sintered after machining while maintaining the proportions. In this case, the working out under a sintering shrinkage corresponding enlargement must be made.

Alternatively, it is possible as in the DE 100 61 630 A1 discloses to infiltrate a porous blank after processing with glass.

In addition, it is known to aufzuschlickern ceramic powders on tooth stumps, pre-sinter this porous and then infiltrated with glasses. Such a method is in the EP 0 241 384 A2 disclosed. The open pores of the blank are impregnated with the glass in a molten state until no more open pores remain.

The erosive methods have the disadvantage that sometimes large amounts of ceramic must be disposed of unused. This is due to the fact that the blanks have a sufficient size for multi-part dental prosthesis parts, such. B. for bridges. On the other hand, often only one item is made. Nevertheless, the size of the dental prosthesis is limited by the size of the blank.

In the case of the slip process, there is the disadvantage that the slip can not be applied in a form-preserving manner due to its flow properties and the production of tooth rows can not be carried out fully automatically. It is necessary for a dental technician to rework the generated dental prostheses. The flow properties further require that the shape of the framework is largely determined by the shape of the stump.

In addition, there is the disadvantage in the case of the slip process that the slurry is not applied uniformly and as a result can result in fault zones and layer boundaries which interfere with the infiltration of glass and thus lead to unusable tooth replacement parts.

Based on the prior art, the object of the invention can be formulated to provide a method for the production of ceramic tooth rows and a dental prosthesis, in which a cost-effective and at the same time accurate and high-quality production of dental prostheses is possible.

Presentation of the invention

The object of the invention is achieved by a method according to the characterizing part of claim 1.

The method for producing a tooth replacement part from 3D data envisages that by means of laser sintering a framework body having an outer geometry of the dental prosthesis part is produced which has a density which is less than a final density of the finished dental prosthesis part and which is suitable for this by means of a subsequent treatment To reach final density.

This method allows the production of individual tooth replacement parts of high quality. The framework body represents a precursor of the dental prosthesis, which does not yet have the necessary final density. This is achieved only by a suitable aftertreatment. As a result, stresses can be avoided, which arise in particular by producing a permanent ceramic dental prosthesis part by means of laser sintering.

The outer geometry of the framework body already corresponds to the outer geometry of the dental prosthesis part to be produced. The dimensions of the outer geometry are chosen so that they take into account any changes in the dimensions by the aftertreatment. The dimensions of the scaffold body thus correspond only in the case already the dimensions of the dental prosthesis part to be produced, if no change in size occurs by the aftertreatment.

In particular, ceramic tooth replacement parts which are produced by means of laser sintering according to the prior art method, have due to the layered structure of the dental prosthesis irregularities in the structure and stresses that can weaken the ceramic dental prosthesis part in its structure. Procedures in which final sintering tooth replacement line are produced by means of laser sintering therefore require intensive post-processing, for example heating for a long period of time to reduce the stresses.

Advantageously, the framework body of the dental prosthesis part is made of ceramic material.

Advantageously zirconium oxide or aluminum oxide are used as the material, and additives which favorably influence the laser sintering process are also used. These may be, for example, admixtures of the same substance with particle sizes in the nanometer range, which have a lower sintering temperature than coarser structures. These formerly melting nanoscale particles improve the heat conduction of the laser energy into the coarser particles. Furthermore come as additives glass or plastics into consideration.

Advantageously, the density of the framework body can be predetermined after laser sintering. As a result, a density can be selected that is tailored to the post-processing.

Advantageously, the density of the framework body after laser sintering is between 10% and 40% of the final density. With such a degree of sintering, an open-pore structure is produced which is readily infiltratable and has very good strength values.

It is particularly advantageous if the laser sintering follows it, a scaffold body is formed, which is structured open-pored. This ensures that, for example, when an infiltration with a filler, all open pores are filled with the filler and a completely dense tooth replacement part is created.

Advantageously, the aftertreatment comprises infiltration with a filler, wherein the framework body already has the final dimensions of the dental prosthesis part to be produced after laser sintering.

Infiltration allows you to close open pores and create great aesthetics. Suitable fillers have good wetting properties and spread well in the framework body to be infiltrated so that no cavities are formed. The thermal expansion coefficient of the fillers must be adapted to the material of the scaffold body. In addition, the melting point of the filler must be lower than the sintering temperature of the material of the framework body. In general, glasses and plastics have proven to be suitable fillers.

It is particularly advantageous if the laser sintering and the infiltration is done in one operation. The material of the skeleton body is mixed with the filler. In laser sintering, in admixtures of, for example, less than 10% of the total mass, filler is added to the material of the framework body. This leads to a lowering of the sintering temperature. The filler has a lower melting point than the material of the scaffold body and is already in the liquid state during sintering before the material of the scaffold body melts. The material of the framework body thus builds up networks with cavities into which the already liquid filler flows.

Advantageously, the aftertreatment provides dimensionally true sintering to final dimensions, the dimensions of the external geometry of the framework body taking into account a shrinkage to the final dimension after laser sintering. By further sintering stresses within the ceramic structure can be reduced and a dense tooth replacement part is created. To account for the shrinkage that occurs during the dimensionally true sintering, a scaffold body with correspondingly larger dimensions is produced by means of laser sintering. The larger dimensions are correspondingly taken into account in the 3D data set, which is used to control the laser sintering process.

Furthermore, the invention relates to a dental prosthesis, which was prepared by the method described above.

Brief description of the drawings

The method according to the invention and the tooth replacement part according to the invention will be explained with reference to the drawing. It show the

1 a known laser sintering plant for carrying out the method according to the invention, the

2A a section of a section through a material container with ceramic material of the laser sintering system 1 during laser sintering, the

2 B an open-pored ceramic tooth replacement part, the

3A a section of a section through the material container 1 with a material mixture and with a finished tooth replacement part and the

3B a closed-pore tooth replacement part produced by the method according to the invention.

Embodiment of the invention

The 1 shows a known from the prior art laser sintering machine 1 which essentially consists of a laser 2 , a power supply 3 . a control unit 4 , a deflecting mirror 5 as well as a material container 6 with material 8th for the production of a tooth replacement part 9 consists.

3D data of the tooth replacement part to be produced 9 or a framework body 14 of the tooth replacement part become the control unit 4 provided by transmission means, not shown. Here, the skeleton body represents a precursor of the dental prosthesis, which already has the outer geometry of the dental prosthesis, but not yet a necessary end density. The control unit 4 decomposes these 3D data, which are usually 3D volume data, into individual layers and calculates paths for a laser beam for these layers 7 the laser 2 , Based on this control data, the control unit controls 4 the laser 2 , the deflection mirror 5 and one in the material container 6 located height-adjustable floor 10 as well as a roller 11 , The deflection mirror 5 serves to the laser beam 7 along the through the control unit 4 controlled way. The laser beam 7 is on the surface of the material 8th in the material container 6 focused.

After completion of a layer becomes the floor 10 through the control unit 4 adjusted by a layer thickness down and by means of the roller 11 a new layer of the material 8th applied.

This process is repeated until the framework body 14 of the tooth replacement part to be produced 9 is completely built up in all layers.

Powder which remains unsintered in the structure of the finished dental prosthesis does not contribute to the stability of the dental prosthesis. But it is harmless if the given properties of the material for. the application as a dental prosthesis are sufficient.

In 2A is a section of a section of itself in the material container 6 located, for example, ceramic material 8th shown enlarged. The laser beam 7 is on the surface of the ceramic material 8th focused, wherein the width d _{L of} the focus of the laser beam 7 is about 5 times larger than the dimensions of an average sized ceramic granule d _k . The laser beam 7 thereby causes a simultaneous melting of several grains of the ceramic material 8th , The focus in the beam of the laser beam 7 located ceramic granules melt on the already finished part of the porous frame body of the dental prosthesis 9 on and enter into each other a network-like connection.

After a layer has been completely produced, if it is a granular ceramic material 8th act, the already completed part of the framework body 14 lowered to another layer on the already completed part of the scaffold body 14 apply. If it is a liquid material, the already completed part of the framework body 14 with a new layer of ceramic matrix 8th overdrawn.

The laser beam 7 and the basic ceramic substance 8th move with one to the desired material properties of the resulting dental prosthesis 9 adjusted relative velocity v in a convenient direction. Preferably, the laser beam travels coherent tracks within the denture structure.

2 B shows the according to 2A prepared framework body of the dental prosthesis 9 as a whole. The framework body is open-pored, the degree of sintering being approximately 40%. The open pores will then have a size of 50-80% of the mean grain size of the powder.

The aftertreatment can be done in two ways. On the one hand, the skeleton body 14 sintered by a further sintering process to the final density of as 99% of the theoretically possible density. Then the scaffolding body 14 of the tooth replacement part 9 produced magnified during laser sintering, so that the shrinkage produced during sintering is compensated.

On the other hand, the post-treatment can be carried out by infiltration with a filler, for example plastic or glass. For this purpose, the open-pored scaffold body with the liquid filler, for example, pressure-impregnated. But it can also be used any other physical effect to the filler in the framework body 14 to bring in, for example, the capillarity.

In 3A is the production of a dental prosthesis 9 represented, which is already infiltrated with glass during the laser sintering. This becomes a ceramic component 8th represented by circles, a glass component 13 as a filler, represented by diamonds, in the material container 6 added.

The glass component 13 has a lower melting point than the ceramic material 8th so that the glass component 13 It melts earlier and is already fluid while being made of the ceramic material 8th the framework body as a ceramic network 14 which forms the tooth replacement part 9 lends its stability. The spaces between the framework body 14 be through the liquid glass component 13 filled and produce the filling 15 , for example glass.

3B shows the finished closed-pore tooth replacement part 9 , in which at the same time the ceramic framework 14 produced by laser sintering and the infiltration was carried out by means of glass.

LIST OF REFERENCE NUMBERS

1

Laser sintering unit

2

laser

3

power supply

4

control unit

5

deflecting

6

material containers

7

laser beam

8th

Material of the framework body, for example ceramic

9

dental prosthesis

10

adjustable floor

11

roller

13

filler

14

scaffold body

15

Filling, for example glass

v

relative speed

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 99/47065 [0004]
• DE 10061630 A1 [0005]
• EP 0241384 A2 [0006]

Claims (10)

Method for producing a tooth replacement part ( 9 ) from 3D data, characterized in that by means of laser sintering a framework body ( 14 ) with an outer geometry of the tooth replacement part ( 9 ) of a material ( 8th ) having a density which is less than a final density of the finished dental prosthesis ( 9 ) and which is suitable for achieving this final density by means of a post-treatment. Method according to claim 1, characterized in that the framework body ( 14 ) of the tooth replacement part made of ceramic material ( 8th ) will be produced. A method according to claim 2, characterized in that as a ceramic material ( 8th ) Zirconia or alumina is used and that preferably additives are used, which favorably influence the laser sintering process. Method according to one of claims 1 to 3, characterized in that the density of the scaffold body ( 14 ) can be predetermined after the laser sintering. A method according to claim 4, characterized in that the density is between 10% and 40% of the final density. Method according to one of claims 1 to 5, characterized in that the framework body ( 14 ) of the tooth replacement part ( 9 ) is porous. A method according to claim 6, characterized in that the aftertreatment an infiltration of the framework body ( 14 ) with a filler ( 13 ), wherein the external geometry of the framework body ( 14 ) after laser sintering has dimensions which are already final dimensions of the finished tooth replacement part ( 9 ) correspond. A method according to claim 7, characterized in that the laser sintering and the aftertreatment are carried out in a single operation, wherein the framework body ( 14 ) of the tooth replacement part ( 9 ) in one operation with the laser sintering by admixing the filler ( 13 ) to the material ( 8th ) of the framework body ( 14 ) is formed and infiltrated, the filler ( 13 ) a lower melting temperature than the sintering temperature of the material ( 8th ) of the framework body ( 14 ) Has. Method according to one of claims 1 to 6, characterized in that the post-treatment a dimensionally stable sintering of the framework body ( 14 ) to a final dimension of the tooth replacement part ( 9 ), wherein the dimensions of the outer geometry of the framework body ( 14 ) take into account a shrinkage to the final dimension after laser sintering. Ceramic tooth replacement part ( 9 ), characterized in that it was prepared by a method according to any one of claims 1 to 8.

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