SE518905C2 - Procedure for dental restoration - Google Patents

Abstract

The present invention relates to a method for producing a dental restoration of at least part of at least one tooth. The method comprises measuring the surface of a preparation replica (1) of a preparation, for which the dental restoration is intended, and storing information about the topology of the preparation replica (1) in a data storage means (3), and creating a computer model (4) of the dental restoration, whereby at least some of the information stored in the previous step is used and/or user inputs from a computer operator is registered. At least one tool path is generated for the control of a machining equipment (5), using the computer model (4), and a restoration replica (6) is machined in a restoration replica material, using the at least one tool path. Finally a mould (7) is formed, using the restoration replica (6), and the dental restoration is cast, using the mould (7).

Description

20 25 30 o u n u of 518 905 CAD / CAM-based systems from the manufacture of dental restorations are known in the art, for example: 0 Duret: “Vers unit prothèse inforrnatisée” Tonus Dentaire no. 73, 1985 p. 55-57, v Duret et al: “CAD-CAM in dentistry”, JADA, vol. 117, nov. 1988, p. 715-720, 0 Williams: ”Dentistry and CAD / CAM: Another French Revolution”, Journal of Dental Practice Administration, J anuary / March 1987, 0 Sjölin, Sundh, Bergman: “The Decim System for Production of Dental Restorations” , International Journal of Computerized Dentistry 199913 [1].

The first CAD / CAM systems for the manufacture of dental restorations thus emerged in the 1980s. In a dental CAD / CAM system, a method is used that includes measuring the surface of the plaster model, which is produced in the same way as in the wax melting method described above. Data regarding the topology of the prepared tooth and possibly also the surrounding teeth are stored in a computer. An operator interacts with the CAD part of the system to design the restoration on the scanned surface and to create a computer model of the desired restoration. The computer model is transferred to the CAM part of the system, where toolpaths are generated for processing the restoration based on a given raw material, made of, for example, ceramics or metal. In the last step, the toolpaths are transferred to a CNC machine for machining.

The CAD / CAM systems use the possibilities that computers and software offer for designing the restaurant more or less automatically in a cost-effective way. In the manufacturing step, however, there are certain costs that are difficult to avoid: 1. When machining in ceramics or metal, there is always a significant cost for tool wear. 2. When a CNC machine is used for manufacturing, there will always be a significant cost of capital. 10 15 20 25 30 I o u | en 518 905 3. When machining in expensive materials, such as gold alloys or the like, there is a need for a cost-effective recycling system for the shavings and surplus materials. 4. When expensive materials, such as gold alloys or the like, are to be machined from a solid block instead of cast, there must be a much larger amount of such material, say ten times more. Although most of it could be recycled at low cost, the presence of an expensive material can already cause problems and costs, attributable to safety. SE 470 346 B describes a process for the production of artificial dental restorations of ceramics. The method comprises the steps of: recording the surface of a prepared tooth using a three-dimensional optical method on a plaster model of the preparation, - reproducing the recorded surface (of the preparation) on a first body using a computer-controlled cutter, - designing a second body by expanding the recorded surface and milling an outer surface corresponding to the expanded surface, or by applying wax to the first body, - generating an imprint of the second body in an elastic material, - use of the first body and the imprint of a press tool, and - designing a cap using the press tool in a die casting process.

The procedure according to SE 470 346 B is intended for an industrial process, which involves heavy and expensive equipment, which is not easily made accessible in a dental laboratory. Furthermore, the method according to SE 47O 346 B cannot easily be used in the continuous casting procedure which at present used in laboratories. OBJECT OF THE INVENTION The object of the present invention is to provide a method for producing a dental restoration, which method reduces or avoids the above-mentioned problems. .

A further object of the invention is to provide a method for producing a dental restoration, which is more time efficient than traditional casting methods, and which can be easily realized in establishments where traditional. casting procedures are used.

SUMMARY OF THE INVENTION The object of the invention is achieved by a method according to claim 1.

By generating a data model for the execution of the restoration, instead of - as is the case with the wax melting method - sculpting by hand in wax material, the labor cost is reduced. The tool cost for machining in wax will be considerably lower compared to machining in ceramics or metals. Because the processing time per restoration will be shorter, when processing in wax compared to processing in other materials, the cost of capital per restoration will be lower. Since the method according to the invention does not give rise to the need for a recycling system for any material which at present used for restorations, there is also no need for expensive filtration systems for capturing contaminants in the recycled restoration materials. There is no need for maintenance service and no safety system for handling a large amount of gold. 10 15 20 25 | DESCRIPTION OF THE DRAWING FIGURES The invention will now be described in more detail with reference to the accompanying drawings, in which Figures 1-4 are schematic perspective views of articles used in steps of a method described below. Fig. 5 is a schematic perspective view of an article used in a method according to an alternative embodiment of the present invention.

DETAILED DESCRIPTION In the following description, the term preparation includes a prepared tooth, a prepared number of teeth or a prepared part of a tooth. To produce a restoration for a preparation, the first step is to create an exact copy of the preparation, here referred to as a preparation copy. This is done, in a known manner, by creating a bite impression of the preparation, using a suitable material, usually silicone. The preparation copy, often made of gypsum material, is made by allowing the silicone to come into contact with the gypsum material.

Fig. 1 shows an action step in the method according to the present invention, whereby the surface of the plaster model, i.e. the preparation copy 1, is measured, using a measuring device 2. Data regarding the topology of the prepared tooth is stored in a data storage means 3, for example a computer 3. The measurement could also include surrounding teeth, whereby data for the topology of these teeth would also be stored. .

With reference to fi g. 2, and using a suitable software, such as a CAD / CAM system, a data model 4 of the desired restoration is created, using and using data acquired in it in fi g. 1 showed the step. An operator 10 15 20 25 51 s 905 íLÉï-aß-: ê can interact with the finding part, for example the CAD part of the system, to design the restoration on the scanned (scanned) surface, whereby different types of software tools can be at hand to make finding work easier and faster.

The computer model 4 is transferred by means of the software to the manufacturing part, for example the CAM part, where tool paths for controlling a machining equipment, such as a CNC machine, are generated.

With reference to fi g. 3, the tool paths are transferred to a CNC machine 5 for processing a restoration copy of the dental restoration. The CNC machine could be of the type commonly used in dental laboratories for machining a restoration, based on ceramics or metal. Preferably, a material with a relatively low evaporation temperature is used for the restoration copy 6. The material could be wax of the type commonly used in dental laboratories, for the wax melting method, as is known to those skilled in the art. Alternatively, plastic or some other suitable material could be used for the restoration copy 6.

With reference to fi g. 4 applies to the wax restoration, ie. the restoration copy 6, is embedded in a material which will form a mold 7, which will obtain an inner surface which is substantially complementary to the outer surface of the restoration copy 6. The material for the mold can be one that is commonly used in dental laboratories.

Preferably, by raising the temperature of the mold, the material of the restoration copy is removed by allowing it to evaporate. For this purpose, one can use a kiln equipment commonly used for the wax melting method (lost-wax wax in the art). Alternatively, the material 6 of the restoration copy can be removed by allowing it to melt.

Then the restoration is cast by allowing a metal or other material in a surface or semi-surface mold to enter the mold through a special channel 8. A technique that could be used during casting, to make the surface or semi-surface material reach all parts of the mold, is either rotation, which generates centrifugal force, or the use of vacuum / pressure, in the same way as occurs according to the wax melting method.

Fig. 5 shows an alternative processing step in the method according to the invention. A restoration copy blank, preferably in wax material, used for processing the restoration copy 6, may be provided with a protrusion 9. The protrusion may serve as a fastener in the CNC machine, whereby it is held with a holding device in the machine, to fix the blank during processing. Then, during the completion of the mold, the protrusion 9 can be used as a channel plug 9. When the restoration copy material is removed, for example by evaporation, as described above, the channel plug 9, which is made of the same material as the remaining part of the restoration copy 6, is also removed. a channel is provided in the mold, which can be used to introduce the restoration material into the mold during casting.

In the described method, a CAD / CAM system is used to allow the computers to do the time-consuming design work, while an efficient casting process is used to avoid the disadvantages of processing directly by the restoration.

Claims (1)

1 0 15 20 25 518 905 8 Patent claims. A method for producing a dental restoration of at least a part of at least one tooth, which method comprises the steps of step: measuring the surface of a preparation copy (1) of a preparation for which the dental restoration is intended, and storing information about the preparation copy (1) topology in a data memory (3), creating a computer model (4) of the dental restoration, whereby at least some of the information stored in the previous action steps is used and / or user signals from a computer operator are recorded, generating at least one toolpath for controlling a machining equipment (5), using the computer node (4), machining a restoration copy (6) in a restoration copy material, using the at least one toolpath, designing a mold (7), using the restoration copy (6), and casting the dental restoration using the mold (7). . A method according to claim 1, wherein the machining equipment (5) is a CNC machine (5) -. A method according to any one of the preceding claims, wherein the restoration copy material has a melting point below the melting point of a casting material used to produce the mold (7). . A method according to any one of the preceding claims, wherein the restoration copy material has an evaporation temperature below the melting point of a mold material used to form the mold (7), and wherein the mold shaping step is followed by removal of the restoration copy by allowing the material 1018 518 905 9 evaporates by exposing the mold to a temperature that exceeds the evaporating temperature of the restoration copy. . A method according to any one of the preceding claims, wherein the restoration copy material is a wax material. . A method according to any one of the preceding claims, wherein the measuring step comprises measuring at least one tooth, or a part thereof, near the preparation, and storing information about the topology of the at least one tooth in the data memory (3). . Method according to one of the preceding claims, wherein the restoration copy is processed starting from a raw material, provided with a projection (9), for fixing the blank in the processing equipment (5) during processing of the restoration copy, and the projection (9) is used to form a channel. in the mold (7), for supplying restoration material during casting.