Cast abutment with enhanced geometry

p0001The present invention relates generally to a casting abutment for a dental implant with an improved geometry and in particular a casting abutment for a dental implant with an improved geometry which is suitable for the production of a dental prosthesis made of a noble metal such as gold or of a metal alloy by means of a lost wax process.

State of the art

p0002In dentistry casting abutment have become diverse known for receiving a dental prosthesis. On the occlusal part of the casting abutment a natural tooth structure of reproduced (dentures) is attached. These are then mechanically connected to a generally dowel-like dental implant, that was previously implanted in the jaw bone of a patient.

p0003Such structures are known to be prepared as follows. First, a wax model is modeled on the casting abutment, which is modeled after the shape of the natural emulated tooth, the wax model is usually created with a fitted onto the casting abutment modeling plastic, facilitates treating and freeing up the access channel for the occlusal. At the end of the modeling, a structure on the casting abutment from wax produced.

p0004The casting abutment with aufmodelliertem wax assembly is then embedded in an embedding. During the casting process necessary for heating the mold, the wax of the dental model and the modeling aid evaporate without leaving any residue. This creates the negative mold, which is subsequently poured out with a noble metal such as gold or a noble metal alloy (hereinafter referred to simply referred to as a noble metal). Thus, a metal model that corresponds to the aufmodellierten on the casting abutment wax structure is created (referred to simply as Angus model called).

p0005The above process is, as is well known in the art, as investment casting (lost wax method), respectively.

p0006After preparation of the casting model that is then usually veneered with a ceramic layer, so as to achieve a more natural reproduction of the tooth to be replaced.

p0007In preparing the casting model using the conventional lost wax process has been found that you may experience an overflow of the precious metal under the collar area of ​​the casting abutment which has undesirable effects, such as casting beads result. The overflow is due to insufficiently cleaned surfaces of the casting abutment. Casting defects can lead to inaccurate fit or gapping between casting abutment and dental implant. Such faulty Angus models are due to the high demands of an exact connection between casting abutment and dental implant and the long-term requirements for dental prostheses not to use and must be re-established.

p0008Furthermore, in the casting abutment with a straight collar area (ie a vertical to the longitudinal axis of the casting abutment collar area) especially problematic that these often tend the gate of the precious metal in an overflow or an overshooting of the cast, heated to high temperatures, high liquid molten precious metal. This is due among other things to an unfavorable flow behavior of the molten precious metal on the collar area of ​​the casting abutment.

p0009To solve the above problem, a layer of graphite is applied as a Gold stop in the areas where you want to stop the flow of the melt of the precious metal usually. However, this results in the contact areas between the noble metal and the surface covered with graphite disadvantageous to the fact that graphite particles can contaminate the precious metal.

p0010Therefore, it would be desirable to provide an improved casting abutment which is able to provide error-free communication between the casting model and the dental implant, even after the casting process. This is particularly important since the resulting high pressure forces during mastication provide immensely high demands on the materials used and the fit, form the connection between casting model and the dental implant. Minor errors in modeling and the Angus operation can cause the metal model of the dental prosthesis is no longer usable or needs to be reworked at considerable expense. Also possibly occurring cracks, impurities, columns or irregularities must be avoided as this would prejudice the long-term mechanical strength.

Summary of the Invention

p0011The present invention therefore has the object to provide a casting abutment with an improved geometry for a dental implant which avoids the problems cited above.

p0012Within this aim, a particular object of the present invention to implement a casting abutment for a dental implant, which causes a braking of the cast precious metal of the prosthesis.

p0013In addition, a particular object of the present invention to provide a casting abutment for a dental implant, which ensures an optimized flow behavior of the molten precious metal.

p0014Furthermore, it is an object of the present invention to implement a casting abutment which minimizes the use of graphite as a barrier or stop for the noble metal, the noble metal melt. Thus, graphite can be avoided except for small applications.

p0015The above objects and further the following description to be taken objects are achieved by a casting abutment according to claim. 1 Advantageous developments of the present invention are the subject of the dependent claims.

Brief Description of the Figures

p0016Further features and advantages of the present invention as well as the operation of the exemplary embodiment of the present invention are described below with reference to the accompanying drawings. The accompanying drawings illustrate the present invention and together with the description, further serve to explain the principles of the invention and to enable a person skilled in the art to make the invention and use. They show:<ul><li><figref idrefs="f0001">Fig. 1A</figref> a side or approximal view of a casting abutment according to a preferred embodiment of the invention;</li><li><figref idrefs="f0001">Fig. 1B</figref> an oblique view from below the <figref idrefs="f0001">Fig. 1A</figref>; </li><li><figref idrefs="f0001">Fig. 2A</figref> an approximal view of a casting abutment of <figref idrefs="f0001">Fig. 1A</figref> in full section with mounted modeling aid; and</li><li><figref idrefs="f0001">Fig. 2B</figref> a plan from diagonally above the <figref idrefs="f0001">Fig. 2A</figref>,</li></ul>

Description of the preferred embodiments of the invention

p0017Referring to <figref idrefs="f0001">Figures 1A and 1B</figref> is a presently preferred embodiment of the casting abutment for a dental implant with an improved geometry, described according to the present invention. The casting abutment generally designated by the numeral 1 has an apical base part 2, one at the base part 2 coronal subsequent transition part 3, an occlusal portion 7 connects to the coronal with an apical lying, circumferential collar region A, the collar area A with an axially closer lying the first platform 4 and formed with at least two subsequent rotating step portions 8, 9 and 10, 12, which together form a collar surface, with the largest diameter of a first step section 8, 9 is smaller than the smallest diameter of which with respect to first step portion 8, 9 apical, second step portion 10, 12. In other printer 12 as a radially extending from the first platform to the outside staircase effect the two stage areas 8, 9 and 10 respectively.

p0018The occlusal portion 7 is rotationally symmetrical and has a substantially cylindrical shape. Subsequently extends substantially in horizontal direction, the first platform 4, which is adjacent to the medial side to the outer edge 5 of the cylindrical shape of the occlusal portion 7 and is formed substantially flat. The first platform 4 preferably has an angle of 80 to 100 degrees with respect to the longitudinal axis of the casting abutment 1, and more preferably an angle of about 90 degrees with respect to the longitudinal axis of the casting abutment 1st

p0019The first platform 4 goes to its distal side in a first tapered portion 8 of the first step section 8, 9 above, which is preferably at an angle of 35 to 55 degrees and more preferably of about 45 degrees with respect to the longitudinal axis of the casting abutment 1 to the bottom is inclined. The first platform is 4 times as wide as the total height of the first step section 8, 9 in a preferred embodiment, 1.5 to 2.

p0020a first vertical section 9 connects to the end edge of the first tapered portion 8, which extends parallel in respect to the longitudinal axis of the casting abutment 1 substantially. The first vertical section 9 is about the height of the overlying first chamfered portion. 8

p0021The first vertical portion 9 merges into a second beveled chamfer 10 of the second step portion 10, 12, which is preferably also inclined at an angle of 35 to 55 degrees and more preferably an angle of 45 degrees with respect to the longitudinal axis of the casting abutment 1 to the bottom and is followed by a second vertical portion 12 connects, which extends substantially parallel with respect to the longitudinal axis of the casting abutment 1, and which has about 25% of the height of the first vertical portion. 9

p0022Directly subsequently to the second vertical portion 12, preferably extends a second platform 13 having about one third of the width of the first platform 4th The second platform 13 also extends in the horizontal direction and is substantially planar. The second platform 13 comprises analogously to the first platform 4, preferably an angle of 80 to 100 degrees with respect to the longitudinal axis of the casting abutment 1, and more preferably an angle of about 90 degrees with respect to the longitudinal axis of the casting abutment 1. When present, forms the second platform 13 and a portion of the collar area.

p0023<figref idrefs="f0001">Figure 2A and 2B</figref> Show the casting abutment 1 of the invention with slotted cylindrical modeling 11, consisting of burn-out plastic and can easily be put on the casting abutment 1, in different views. Plastic must always be covered with a certain waxy starch which as a "buffer" with respect to serving in the muffle swelling of the plastic during the burnout operation. Without such a "buffer" there may be a blasting the investment. Therefore, the prefabricated plastic channel is inserted only to a certain extent in the occlusal area about Angus Gold member to the bottom of the sprue to provide enough space for a maximum individual wax modeling (section B). In the collar region indicated by reference character A, the two platforms 4, 13 and the at least two stepped portions 8, 9, or 10, 12 are arranged, which allow a very uniform flow around the collar surface when the liquid metal alloy through a channel in the embedding compound ( not shown) is poured.

p0024The layers 9 and 10, 12 formed by the platforms 4, 13 and the stepped portions 8, which act like a staircase, also the melt of the noble metal to the end areas of the casting abutment 1 and avoid brake so that as the application of potential barriers such as for example, graphite. The first platform 4 is advantageously wider, so as to allow a large contact area of the melt of the precious metal with the occlusal part 7 and the first platform 4th The step portions 8, 9, or 10, 12 reduce advantageously to be applied amount of precious metals, as this has to be applied only in the outer regions. The Stufenbereic hey 8, 9, or 10, 12 effect on the collar face similar constant wall thickness of the metal model, which is also effective in reducing the thermal shock upon impact of the enclosed highly heated molten precious metal on this relatively cool collar area, and hence to avoid cause deformation of the casting abutment. 1

p0025Although the invention has been described in conjunction with a one-piece casting abutment, is for the relevant skilled artisan readily understood that it is similar with two-piece casting abutment, it being understood that the same advantages as in the context of a one-piece casting abutment described, are achieved. Also, the number of the step portions can be increased with respect to the embodiment shown, in practice, good results have been obtained with three, four or five step portions. In fact, is desirable to maximize the number of stages ranges in practice, the number of which ultimately, as known to the skilled man, is determined taking into account the available space and manufacturing constraints.

p0026If in any of the claims mentioned technical features are provided with a reference signs, those reference signs have been included only to increase the intelligibility of the claims. Accordingly, such reference signs do not have any limiting effect on the scope of each element, which is referred to by way of example by such reference signs.