METHOD AND DEVICE FOR A PRODUCT INTENDED TO BE INTRODUCED INTO THE HUMAN BODY, AND SCANNING DEVICE FOR A MODEL OF THE PRODUCT

Abstract: A dental bridge can be manufactured with the aid of a model (2) which includes preparations (8, 9, 10). The contours of each preparation can be read off by a reading unit. A computer unit traces the said readings. With the aid of a computer program, the computer processes the read-off information in cooperation with an operator so that a construction based on the tracing is obtained. The position of each preparation in the construction is determined by an apparatus which is functionally separate from the scanning unit. This apparatus generates information items which can be related to the positions of the preparations. These information items are run concurrently with the readings from the scanner in the computer, which in this way can indicate the correct mutual positions of the preparations in the construction.

Description: TITLE Method and device for a product intended to be introduced into the human body, and scanning device for a model of the product. TECHNICAL FIELD The present invention relates to a method for manufacturing a product which can be used in the human body, preferably a dental bridge, with the aid of a model comprising different parts, for example preparations. The method utilizes a scanning unit by means of which the contours of the parts can be read off and can be represented by electrical, preferably digital, representations. Also included is a computer unit (micro¬ processor) which operates with data or information items which can be related to the representations and which are arranged in files. With the aid of a computer program, for example of the CAD program type, the computer processes the said data in cooperation with an operator in order to create, on a computer screen, a construction which is based on the read-off representations. The computer can also provide processing information items which represent the said construction and which are used in equipment for manufacturing or machining of the construction, which can in this case be made in the form of a blank, for example of titanium. The invention also relates to a device for implementing the said method. The invention furthermore deals with a device for scanning parts of a model, preferably a model in the form of a dental bridge or equivalent dental product with parts in the form of one or more preparations, for manufacture of a construction. A digital representation, obtained as a function of the scanning or reading, of the contours of the parts or preparations is obtained from the scanning unit and supplied to the computer. Also included in the said representation are data concerning the mutual positions of the parts or the preparations on the model in question. The computer unit is arranged to create on the screen, as a function of the supplied representation and with the aid of a program, for example a CAD program, in cooperation with a user or operator, a construction, for example a dental bridge, which is based on the model. STATE OF THE ART In the manufacture of dental bridges, for example, it is already known to use a scanning unit and computer for simulating a construction based on the scanning. The computer can also, in a known case, calculate machining coordinates for production of the construction in question. DESCRIPTION OF THE INVENTION TECHNICAL PROBLEM There is a need to be able to produce dental bridges, for instance, in a relatively technically simple and computerized manner. In this case it is important to be able to indicate correctly not only the different shapes of the dental bridges, but also the relationship between the parts, at the same time as an appropriate and rapid scanning function can be used. The invention solves this problem, among others. In the manufacture of dental products, it has been found to be advantageous to use a scanning unit in which the reading function (the beam, needle, etc) is directed obliquely to the axis of the respective dental bridge part, at the same time as the dental bridge part is rotated about its said axis. In this way it is possible to operate in the polar coordinates system, which reduces reading times, data quantities, etc., despite which complicated contours can also be read off. However, there is a clear problem in combining such a tracer principle with computer-aided construction in accordance with the above. The invention solves this problem too. It is important that equipment known per se, such as scanning apparatuses, computers, computer programs, etc., can be used. Thus, for example, it is advantageous if standard software can be used. The invention also solves this problem and permits the use of CAD programs which are known per se for producing the construction. SOLUTION The feature which can principally be regarded as characterizing a method according to the invention is that the position of the respective preparation in the construction is determined using an apparatus or levelling apparatus which operates separately from the scanning unit, at least from the functional point of view. The apparatus generates information items which can be related to the positions of the preparations and which are run concurrently with or transform the read-off representations (the files) in the computer, which in this way can indicate the mutual positions of the preparations in the construction which is being made on the computer screen and is then used for manufacturing the dental bridge. In a preferred embodiment, use is made of a support plane or a levelling platform on which the model can be arranged and can be displaced in the plane so that the preparations can be moved or adjusted to a vertical position. The platform or plane can be turned about two axes, which extend through the plane and are at right angles to one another, in order to provide, in each reading position, a vertical position for the preparation in the model such that the scanning unit which traces the contour of the respective preparation can read off the whole contour, without there being any undercuts or areas concealed from the scanning unit. The adjustments of the model in relation to the plane, i.e. the position of the model in the X and Z directions and the inclination of the plane or platform in the respective reading position, are detected and indicated by equipment. The detected information items are thereafter transferred to the computer unit which uses the information in question for the said concurrent running. The information from the equipment is also arranged in files which can be run concurrently in the computer equipment. Further embodiments of the novel method are evident from the attached subclaims relating to the method. The feature which can principally be regarded as characterizing the novel device for implementing the said method is evident from the characterizing clause of attached Patent Claim 8. A device for scanning a model can be regarded as being characterized in that a support member, for example a levelling platform, is arranged to support the model, which can be activated on a [lacuna] relative plane, i.e. either the model is displaced relative to the plane or the plane is displaced with the model fixed, so that the preparations can assume one or more reading positions. The support plane or the levelling platform is arranged such that it can be turned or tilted so that the respective preparation can be allocated a desired position in the vertical direction. By means of this adjustability in the vertical direction, the contour of the respective preparation can be made accessible to the scanning principle which is used in conjunction with the invention. The position of the model in the X, Z plane, and the inclinations of the plane or the platform in the respective positions, are read off by means of equipment which generates information for the computer concerning the said adjustments of model and plane/platform. The information can, upon execution or processing in the computer, and upon the interaction with an operator, represent the positions of the preparations in the construction formed on the computer screen. In one embodiment, the formed construction is sectioned upon production of machining coordinates. ADVANTAGES By means of what has been proposed above, reading equipment which is known at present can be used for inputting basic data for construction of bridges in a computer. By means of the invention, it is possible for data describing the positions of the individual preparations relative to one another to be collected along the scanning function. DESCRIPTION OF THE FIGURES A presently proposed method and device according to the invention will be described hereinbelow, at the same time with reference to the attached drawings in which: Figures 1 - 7 show successive manufacturing stages for production of a construction unit based on a model, and Figure 8 shows, in circuit diagram form, processing stations included in processing equipment according to the invention. DETAILED EMBODIMENT In Figure 1, reference number 1 indicates a plane which can consist of a support platform of a levelling apparatus known per se. A model 2 is applied on the platform. The plane or the platform has an axis 3 which extends at right angles to the plane 1. The axis 3 represents a reading position. The model is displaceably arranged on the platform in the directions of the arrows 4, 5. The platform operates with two axes which are at right angles to one another and which are here designated as the X and Z axes. The plane or the platform 1 can be turned about the said axes in the directions of the arrows 6 and 7. The model 2 includes a number of prepara¬ tions 8, 9, 10, etc. The model can alternatively be fixed in the platform 1 in a manner known per βe, in which case the platform in turn can be displaceable in the directions of the arrows 4 and 5. In this way, each preparation can be brought one at a time into line with the reading position which is represented by the line 3. Equipment 11 is in this case arranged to trace the X and Z positions as well as the current angles of rotation of the axes 6 and 7. The tracing can be effected in a manner known per se. In Figure 2, the model 2 has been displaced with the aid of the platform 1 so that the axis 12 of the preparation 8 coincides with the axis 3 which represents the tracer position. This movement of the platform is indicated by tracer signals il and i2 in Figure 1, which tracer signals are input to the tracer equipment 11. The next stage is to orient the preparation 8 in the vertical direction. According to Figure 1, the preparation is inclined in relation to the axis 3 by an angle gamma. This inclination can mean that undercuts and certain areas are inaccessible for the scanning which is effected in the subsequent operational step. There is therefore a need to carry out the said straightening of the preparation 8. In accordance with Figure 3, this is done by the plane 1 being turned about the axes X and Z. In this way, the axis 12 of the preparation 8 can be made to coincide fully with the axis 3 or to coincide essentially with this axis. These changes in the angle of rotation of the axes are represented in Figure 1 by signals i3 and 14. These signals too are recorded in the tracer equipment 11. In accordance with Figure 4, the preparation 8 can be provided with a handle 13 or other gripping member, with which the preparation can be transferred to a scanning unit according to Figure 5. The scanning unit too has a rotating platform 14 on which the preparation 8 can be applied or fixed in a defined position. The scanning apparatus is of the type which has a tracer function 15 in the form of a needle, optical tracer, etc. A rotation arrow for the said platform 14 is indicated by 16. The longitudinal axis of the tracer member or tracer function is indicated by 17. The tracer apparatus is characterized by the fact that the platform 14 is rotated, at the same time as the tracer member 15 and the preparation 8 move reciprocally in the vertical direction 18. Either the platform can be stationary in the vertical direction and the tracer function can move in the vertical direction, or vice versa. Alternatively, both the platform and the tracer function can be vertically displaceable. The handle can be removed during this tracing operation. The attachment of the handle 13 can also be made on a part of the preparation which will not be traced by the scanning equipment, which means that the handle is not in the way. Figure 6 shows a computer screen 19 of a computer which is known per se and which is used in this connection. The preparations forming part of the bridge or equivalent are transformed on the basis of the read- off data which is input to a random CAD program. On the said preparations, a bridge will be constructed in accordance with Figure 7. The construction procedure takes place in a manner known per se by interaction between the computer and a user or operator. In Figure 7, a bridge produced on the preparations 8', 9' and 10' is indicated by 20. The bridge is constructed and sectioned in the computer. The parts are then transformed back so that the milling takes place about the axis of rotation 14a which is used during the reading-off. Figure 8 shows the entire chain of production. The levelling function described above is carried out at a first station. The said scanning function takes place at a second station 22. The axis of rotation is indicated by 14a' . The reference labels in other respects correspond to those which are used in Figure 5, but with a prime symbol added. The digital representation which is obtained from the scanning function is shown by 23 in Figure 8. The computer used in this connection is arranged at a station 24 and functions in accordance with the above. The computer is provided with a terminal 25 for the said interaction with a user. Machining or milling information is indicated by 26, and machining equipment by 27. The machining from a blank 28 also takes place in the polar coordinates system. A tool 29 is indicated in principle and symbolizes a milling cutter or other tool. The blank is rotated about a vertical axis 30. The axis 31 of the tool is inclined, in relation to the axis 32 of the blank, by an angle beta. In a preferred embodiment, the angle beta is the same size as the angle alpha and alpha' . The levelling equipment has the effect that the computer can be fed information which can relate to the said signals il, i2, i3 and i4, which information constitutes digital information 23'. The last-mentioned information is arranged too in files in association with the computer. The data in the files for the information 23, 23' is run concurrently and is used by the computer for producing the construction on the computer screen. Since the reading-off function can read off only one preparation at a time, the data describing the mutual relationship between the preparations must therefore be collected in another apparatus in accordance with the above. This is called a levelling apparatus according to the above, since the rows of teeth can be straightened both as regards angle and translation. Collection of the data which is required can be carried out in the following way: 1. The preparation in question is translated in the X and Z directions so that it is placed in the "read- off position" on the levelling platform. 2. The preparation is straightened by means of the platform being rotated about the X and Z axes so that it can be read off without any undercuts or the like arising. 3. The position of the preparation in the X and Z directions and also the angles about the X and Z axes are read off. 4. A "handle" is secured on the preparation. With the aid of the "handle", the preparation can be transferred easily to the reading-off function. The preparation is then read off in a known manner. The data which has been read off in the levelling apparatus is now used for transforming the read-off files so that they can be seen in their correct positions in a random CAD program. The bridge can then be constructed in the CAD program using the input preparations as basis. The bridge constructed in the CAD program is sectioned in the computer and is transformed back so that the production basis for the inner shapes of the included parts is milled about the centre of rotation with which they were read off. That is to say, the read-off file functions as production basis in the same way as for single crowns. This is to ensure that the transforms will not have an adverse effect on the accuracy. The accuracy requirements are lower as regards the outer shapes, which are thus those which are transformed. The bridge parts are thereafter joined together in the usual way, by laser welding 33 in a known manner. The invention is not limited to the embodiment which is shown hereinabove by way of example, but instead can be the subject of modifications falling within the scope of the attached patent claims and the inventive concept.

Claims: PATENT CLAIMS 1. Method for manufacturing a product which can be used in the human body, preferably a dental bridge, with the aid of a model comprising different parts, for example preparations, and utilizing a scanning unit by means of which the contours of the parts can be read off and can be represented by electrical (digital) representations, and a computer unit which operates with data/information items which can be related to the representations and which are arranged in files, and with the aid of a computer program, for example a CAD program, processes the said data in cooperation with an operator in order to represent, on a computer screen, a construc¬ tion which is based on the read-off representations, processing information representing the said construction being obtained from the computer unit for use in equip¬ ment for manufacturing the construction, characterized in that the position of the respective part/preparation in the construction is determined using an apparatus which is functionally separate from the scanning unit and which generates information items which can be related to the positions of the parts/preparations, and in that the last-mentioned information items are run concurrently with the read-off representations in the computer, which in this way can indicate the mutual positions of the parts/preparations in the construction. 2. Method according to Patent Claim 1, characterized in that the model is applied on a support plane included in the said apparatus, for example on a levelling platform, in that the said parts/preparations are brought one at a time to one or more reading-off positions on the plane, in that the plane is turned about two axes, which extend through the plane and are at right angles to one another, in order to provide for the respective part/preparation, in each reading position, a vertical position in relation to the scanning unit so that the latter is able to read off the whole contour of the respective part/preparation, and in that information on - li ¬ the position of the model on the plane and the said angles of rotation about the said axes is supplied and is used by the computer, together with the read-off representations, in order to determine the correct mutual positions of the parts/preparations in the construction. 3. Method according to Patent Claim 1 or 2, characterized in that the respective part/preparation is provided with a handle or equivalent holding member, by means of which the preparation is transferred to the scanning unit for tracing of the contour of the part/preparation. 4. Method according to Patent Claim 1, characterized in that the scanning unit operates with a reading-off function along an axis which is inclined in relation to the axis of the part/preparation, and in that the part/preparation is rotated about its axis during the reading-off, at the same time as the part/preparation and/or the scanning unit (its reading-off axis) moves in the vertical direction. 5. Method according to any one of the preceding patent claims, characterized in that the construction produced using the program is sectioned in the computer, and in that the machining information includes information on the structure of the sections and their mutual positions/locations. 6. Method according to any one of the preceding patent claims, characterized in that the machining/ milling is carried out in a similar way to the tracing for the preparation of the respective section/part, and each read-off file can serve as production basis in the same way as in manufacture of individual parts/dental crowns, etc. 7. Method according to any one of the preceding patent claims, characterized in that the sections or the bridge parts are joined together by means of laser welding. 8. Device for manufacturing a product which can be used in the human body, preferably a dental bridge, with the aid of a model comprising different parts, for example preparations, and utilizing a scanning unit by means of which the contours of the parts can be read off and can be represented by electrical (digital) representations, and a computer unit which operates with data/information items which can be related to the representations and which are arranged in files, and with the aid of a computer program, for example a CAD program, processes the said data in cooperation with an operator in order to represent, on a computer screen, a construe- tion which is based on the read-off representations, processing information representing the said construction being output from the computer for use in equipment for manufacturing the construction, characterized in that a support plane, for example on a levelling platform, is arranged to support the model so that the latter can be displaced to one or more reading-off positions, in that the support plane is arranged such that it can be turned about two axes, which extend through the plane and are at right angles to one another, in order to provide one or more reading positions for the respective part/ preparation in relation to the scanning unit, so that the latter is able to read off the whole contour of the respective part/preparation, and in that information on the position of the model on the plane and the current angles of rotation about the said axes can be supplied and can be used by the computer, together with the read- off representations, in order to determine the correct mutual positions of the parts/preparations in the con¬ struction. 9. Device for scanning parts of a model, preferably a model of a dental bridge with one or more preparations, for manufacturing the constructions, in which a digital representation, obtained as a function of the reading, both of the contours of the parts/preparations and also of the mutual positions between the parts and the prep¬ arations is supplied to a computer unit which is arranged to create on the screen, as a function of the supplied representation and with the aid of a program, for example a CAD program, in cooperation with a user or operator, a construction/dental bridge which is based on the model, characterized in that a support member, for example on a levelling platform, supports the model, which can be activated on or with the plane so that each part/ preparation can be brought one at a time to one or more reading-off positions, in that the support plane can be turned about two axes, which extend through the plane, in order to permit adjustment of the respective part/ preparation set in the respective tracing position, so that its contour can be read off from a scanning unit, and in that the said representation supplied to the computer includes information derived or extracted from the respective adjustment in the respective tracing position of the position of the part/preparation on the plane and the current angles of rotation of the axes, and in that this information, upon execution or processing and upon the said interaction, indicates, as a function of the extracted information, the positions of the parts/preparations in the construction.

Inventors: ANDERSSON MATTS, PERSSON MAGNUS, ANDERSSON, MATTS, PERSSON, MAGNUS
Applicants: ANDERSSON MATTS, NOBELPHARMA AB, PERSSON MAGNUS, ANDERSSON, MATTS, PERSSON, MAGNUS
Application year: 1995
Main classification: A61C13
IPC codes: A61C9, A61C13, A61C19