METHOD AND DEVICE FOR PRODUCING A MODEL FOR A PROSTHESIS IN THE HUMAN BODY

Abstract: In the production of a prosthesis in the human body, a model (1, 2, 3) of the prosthesis is used. The model has to be secured in a rotatable holder (4) and its outer surface (3a) has to be read during rotation. The model is made up of top and bottom parts which are chosen from amongst a small number of prefabricated modular units. The top and bottom parts of the model are anchored to one another by mutually assigned, oblique assembly surfaces (1a, 2a). The bottom parts are constructed with outwardly sloping outer surfaces and with different maximal heights (H). The choice of the parts is made in dependence upon the vertical extend of the prosthesis in relation to a securement in the bone. At least the top part is provided with malleable material (3), for example wax, by means of which the final shape of the model is accomplished.

Description: METHOD AND DEVICE FOR PRODUCING A MODEL FOR A PROSTHESIS IN THE HUMAN BODY The present invention relates to a method for producing a model for an oral prosthesis in the human body, the prosthesis being able to constitute a replacement for the whole or parts of one or more teeth. The model is designed to be secured in a rotatable holder (which can be constituted by a type which is known per se) and, following securement, to allow its outer surface to be read during rotation through the use of reading members which are known per se. The invention also relates to a device for producing such a model . It is previously known to build models for dentures and constructions which are to be applied to tooth remnants, implants, spacers, etc. in the jaw, see SE 98.01933-4, with wax. The prosthesis or the model is configured in dependence upon the position and construction of the prosthesis in the jaw in relation to the rest of the dental situation. This model-production work is carried out by the dental technician and the production time for and the shaping of the model is largely dependent upon the craftsmanship of the dental technician . There is a need to create a simplified process for the model production and, in particular, there is a need for clear and simple tools which will facilitate the work and will no longer be so highly dependent upon the said craftsmanship. The tools should be easy to use and should enable model production to be speeded up. The invention sets out to solve these problems, inter alia, and proposes the use of a system of tools based on a modular concept for use in production of the model. Model production should be realized in connection with an individual dental situation and, in addition, should be usable for a variety of system platforms in which different types of implants, fixture systems, tooth remnant mounts, spacers, etc, are present. The invention sets out to solve this problem also. Model production should be afforded a production facility and structure which takes care of the strength- related problems, i.e. the model body should have an extent in relation to the direction of securement in the bone, for example the jaw bone, which offers optimal strength and, at the same time, extends in the aesthetically correct direction in the dental situation in question. The invention solves this problem also. What primarily can be considered to be characteristic of the new method is that the model is made up of top and bottom parts which are chosen from amongst a small number of prefabricated top and bottom parts or ones which can be produced step by step. These top and bottom parts are put together and anchored to one another by mutually assigned, oblique assembly surfaces and the said bottom parts are constructed with outer surfaces which slope outwards from the bottom (i.e. from the securement surface) and have mutually different angles of inclination exceeding a predetermined angular value and have different maximal or peak heights. The new method is additionally characterized in that the choice of top and bottom parts and their mutual rotational position in the assembly is made in dependence upon the vertical extent of the prosthesis in relation to a securement in the bone and in that malleable material, preferably constituted by wax, is applied to at least the top part of the top and bottom parts put together in this way, by means of which material the final external shape and the said outer surface of the model are realized. In a refinement of the new method, the said top and/or bottom parts are constructed of material which allows the part concerned to be ground at its respective outer edges to achieve an expedient model frame. What primarily can be considered to be characteristic of the new device is that it comprises a small number of modular units which can be put together and which, in the respective assembly of a model, form top and bottom parts of the model. The modular units have oblique mating surfaces by means of which the respective assembly can be realized. The bottom parts in question are further arranged with surfaces which slope outwards from the bottom (i.e. from the bottom side or base surface of the model) and in which the angle of inclination and the maximal or peak height are different on the different bottom parts. Finally, the new device is characterized in that the respective assembly of the top and bottom parts forms a model frame in which at least the top part or top parts can be allocated malleable material, preferably constituted by wax, by means of which material the final external shape and the said outer surface of the model can be realized. In refinements of the inventive concept, the respective bottom part is constructed with a base part or base surface, by means of which the model can be applied to the holder. The outwardly inclined outer surfaces extend at angles of inclination which, for reading related reasons, must exceed ca. 50°. In one embodiment, three or four different bottom parts and three to four different top parts are used in the modular system, which can be put together in pairs to form the respective model frame. The number of top and bottom parts does not need to be identical and by the term "small number" is here meant the said number of three to four different parts. A preferred embodiment is constituted by the fact that, in the respective frame constructed with modular units, top and bottom parts are fixed to one another by means of glue applied to the oblique surfaces, which glue, by way of example, can here be constituted by cyan acrylate. In the respective model frame, the top and bottom parts can be applied to one another in a mutual rotational-angle relationship relative to the directional axis of the model. The differences between the angle of inclination of the different bottom parts can in one embodiment assume values of around ca . 10°. The said peak height measurements of the different bottom parts can differ, for example, by ca . 1-2 mm. In addition, the oblique mating surfaces can be arranged with different angles in relation to the base surface of the respective bottom part. The above-proposed allows a substantially simplified production process for models of this type comprising modular units, in which the time gain for production of the model in question can amount to 20-50% in relation to the model produced manually only using wax. The new system requires only a small number of modular units which, per se, can be constructed in a suitable material which can easily be worked in connection with the putting-together of the frame parts of the model. As a result of the proposed, it is possible simply and easily to assemble a model frame which offers the most advantageous extent in terms of strength, at the same time as the model frame acquires an extent or direction in relation to the bone securement which meets the prosthodontal and aesthetical requirements. From the small number of modular units, it is easy for the dental technician to choose the top and bottom parts to be used for the dental or corresponding situation in question. The application of the malleable material to the outside of the model frame is a relatively simple process compared with the model having to be constructed on the basis of wax modelling as in the past. DESCRIPTION OF THE FIGURES A currently proposed method and a device which have the characteristics indicative of the invention shall be described below with simultaneous reference to the appended drawings, in which: Figure 1 shows in vertical view and in basic representation a configuration of the model which is connectable to a symbolically represented holder of a type which is known per se and in which the outer surface of the model is scannable by means of a scanning apparatus which, per se, is basically defined, Figure 2 shows from above the model according to Figure 1, Figure 3 shows in vertical view and in basic representation a first dental situation, in which the prosthesis is applied to a fixture system in a partially shown jawbone, Figure 4 shows in vertical view and in basic representation a case which is distinct from the case according to Figure 3, in which the prosthesis is to be connected with a different extent in relation to the extent of the bone securement, Figures 5-7 show from the side and in basic representation embodiments of various bottom parts included in the modular system, and Figures 8-10 show from the side and in basic representation various embodiments of top parts which will be able to be applied to bottom parts corresponding to those according to Figures 5-7. In Figure 1, a model frame is constructed from a bottom part 1 and a top part 2 applied thereto. The bottom part has an oblique top surface la and the top part has an interacting, oblique bottom surface 2a. For example, the top surface can have a protruding male part and the bottom surface a corresponding female part, this having been marked in diagrammatic representation in Figure 1. At least the top part 2 is coated on its outer surface 2b with a malleable material 3, which can be constituted by wax or equivalent of a type which is known per se . The model is thus formed by the bottom part 1 and top part 2 and the wax coating 3. The model can be applied to a holder 4 of a type which is known per se via a bottom surface lb on the bottom part. The holder is arranged such that it is rotatable in a known manner about a rotational axis 5 for the holder and the model. An arrow showing rotation about the axis 5 is indicated by 6. The outer surface 3a of the model will be read with a reading apparatus 7, which can be of a type which is known per se. The reading direction is indicated by 8 and extends at an angle α in relation to the rotational axis 5. During the reading, the reading apparatus 7 and the model 3 and the holder are acted upon one relative to the other, which has been symbolized by the vertical directional arrows 9. The bottom part 1 is provided with a side surface lc sloping outwards from the base surface lb. The angle of inclination has been indicated by β in Figure 1. In order with the obliquely incident reading direction 8, to achieve an expedient reading of the whole surface of the model, which surface, in addition to the surface 3a, also consists of the surface lc, the angle of inclination β must not be less than ca . 50° in the present case. In Figure 1A, a peak or maximal height of the inclined surface is indicated by H. The surfaces la and 2a are obliquely inclined in relation to the base surface lb. In Figure 1, the body for the top part 2 is arranged essentially concentrically about the rotational axis 5. According to the invention, the body can, however, be given a different direction. According to Figure 2, the angle of rotation γ between the top and bottom parts is varied in order to achieve different extents for the vertical extent of the top part in relation to the vertical extent of the bottom part. In Figure 2, a first diametric axis is indicated by 10. This diametric axis can be considered to be assignable to the rotational position of the bottom part. In addition, a second diametric axis 11 is shown, which is assignable to the rotational angle position of the top part relative to the bottom part. By adjusting the angle γ between the said diametric axes 10 and 11, different relative directions can thus be obtained between the top and bottom parts. In Figure 3, a fixture is symbolized by 12 and a tooth bone or jawbone by 13. The prosthesis in question has been symbolized by 14 and in certain cases the extent (vertical extent) 15 of the prosthesis may need to differ from the extent 16 of the implant in relation to the jawbone 13. The invention enables models to be produced which are representative of the said differences. In Figure 4, the implant 12' is shown obliquely inclined in the jawbone 13'. The longitudinal axis 15' of the implant can in this case be considered to be angled in relation to the extent 16' in which the dental prosthesis 14' may be considered to extend. The new model-production process can provide for this case also. Figures 5-10 show examples of a modular system according to the invention. In Figures 5, 6 and 7, the bottom parts 1', l 1 ' and 1''' are shown, which are configured with different angles of inclination β', β'' and β 1 '' respectively and different peak or maximal heights H', H'' and H' 1 ' respectively. The said bottom parts 1 ' , 1 ' ' and 1 ' ' ' are constructed with different inclining outer surfaces lc', lc'' and lc' 1 ' respectively, arranged to correspond to different types of fixture design. According to Figures 8, 9 and 10, the top parts 2', 2'' and 2''' are provided with different configurations and different inclinations of the bottom parts 2a', 2a' ' and 2a''' respectively and different heights K', K 1 ' and K ' ' ' respectively. The parts according to Figures 5-10 will be able to be put together according to choice in order to comply with the production of models for different dental situations. In certain cases, grinding of the parts is carried out. The parts are therefore made in grindable material, for example plastic, metal, alloy (light-bound), wax, etc., the top and bottom parts are put together with glue (fast-acting glue) of suitable type, for example cyan acrylate. The invention is not limited to the embodiment shown above by way of example, but can be subject to modifications within the scope of subsequent patent claims and the inventive concept.

Claims: PATENT CLAIMS 1. Method for producing a model (1, 2, 3) for an oral prosthesis (14, 14') in the human body, for example a prosthesis for the whole or parts of one or more teeth, and in which the model is intended to be secured in a rotatable holder (4) and to allow reading of its outer surface (3a) during rotation, characterized in that the model is made up of top and bottom parts (1, 2) which are chosen from amongst a small number of prefabricated top and bottom parts (1', 1'', 1''' and 2', 2'', 2*'' respectively) or ones which can be produced step by step, in that the top and bottom parts of the model are put together and anchored to one another by mutually assigned, oblique assembly surfaces (la, 2a), in that the said bottom parts are constructed with outer surfaces (lc', lc' ', lc' ' ') which slope outwards from the bottom and have mutually different angles of inclination (β 1 , β 1 ', β' 1 ') exceeding a predetermined angular value, for example ca . 50°, and have different maximal heights (H', H'', H'''), in that the choice of the bottom and top parts and their mutual rotational position in the assembly is made in dependence upon the vertical extent (15', 16') of the prosthesis in relation to a securement in the bone (13, 13'), and in that malleable material (3), for example wax, is applied to at least the top part of the assembled top and bottom parts, by means of which material the said outer surface is realized. 2. Method according to Patent Claim 1, characterized in that, in connection with the assembly of the respective model frame (1, 2, 3), the top and bottom parts (1, 2) are ground at their respective outer edges before the malleable material (3) is applied. 3. Device for producing a model (1, 2, 3) for an oral prosthesis (14, 14') in the human body, for example a prosthesis for the whole or parts of one or more teeth, spacers, etc., which model can be applied in or to a rotatable holder (4) and hereupon exposes its outer surface (lc, 3a) to reading during rotation (6), characterized in that it comprises a small number of modular units (1', 1'', 1'*' and 2', 2'', 2''') which can be put together and which, in the respective assembly, form top and bottom parts (1, 2) of the model, in that the modular units have oblique mating surfaces (la', la 1 ', la''' and 2a', 2a'', 2a''') by means of which the respective assembly can be realized, and in that the bottom parts are arranged with outer surfaces (lc', lc' 1 , lc' ' ') which slope outwards from the bottom and in which the angles of inclination (β 1 , β' 1 , β''') and peak heights (H', H'', H'*') are different on the different bottom parts, and in that the respective assembly of the top and bottom parts forms a model frame in which at least the top part or top parts can be allocated malleable material (3), for example wax, for forming the entire or partial outer surface of the model. 4. Device according to Patent Claim 3, characterized in that the respective bottom part has a base part/base surface (lb), by means of which the model can be applied to or in the holder (4), and in that the respective outwardly inclined outer surface extends at an angle of inclination which exceeds ca . 50° in order to allow reading with a reading angle (α) in relation to the rotational axis (5) of the holder and of the model. 5. Device according to Patent Claim 3 or 4, characterized in that the modular units comprise three or four different bottom parts (1', 1'', I'' 1 ), corresponding to different types of fixture design, and three or four different top parts (2', 2'', 2'''), which can be put together in pairs to form the respective model frame (1, 2) . 6. Device according to Patent Claim 3, 4 or 5, characterized in that, in the respective frame constructed with modular units, top and bottom parts (1, 2) are fixed to one another by means of glue, for example cyan acrylate, applied to the oblique surfaces. 7. Device according to any of Patent Claims 3-6, characterized in that the top and bottom parts in the respective model frame can be applied to one another in a mutual rotational-angle relationship (γ) about the rotational axis (5) of the model. 8. Device according to any of Patent Claims 3-7, characterized in that the angles of inclination (β', β'', β''') of the different bottom parts mutually differ by ca . 10°. 9. Device according to any of Patent Claims 3-8, characterized in that the peak height measurement (H', H'', H' 1 ') mutually differs by ca . 1-2 mm. 10. Device according to any of Patent Claims 3-9, characterized in that the oblique mating surfaces (la', la'', la 1 ' 1 and 2a', 2a 1 ', 2a 1 '' respectively) are arranged at different angles in relation to the base surface (lb) of the respective bottom part.

Inventors: PERSSON MAGNUS, PERSSON, MAGNUS
Applicants: NOBEL BIOCARE AB, PERSSON MAGNUS, NOBEL BIOCARE AB (PUBL), PERSSON, MAGNUS
Application year: 2000
Main classification: A61C13
IPC codes: A61C9, A61C13