Patent Application
20220401195
The disclosure relates to an artificial tooth element, as well as to a prosthesis comprising a prosthesis base and artificial tooth elements.
With known prefabricated artificial teeth, it is necessary that these are shortened at the base side by an orthodontist and that the surface is roughened. Shortening is necessary in order to adapt the basal inner part of the tooth element, i.e. the part of the tooth element that is inserted into the prosthesis cavity and is invisible in the inserted state, to the cavity provided in the prosthesis base. Roughening is required in order to achieve sufficient strength and stability after the fastening, in particular after the insertion and gluing of the tooth element into the prosthesis base. The shortening and roughing of the inner part of the tooth element by an orthodontist has the disadvantage that the accuracy always depends on the manual skills of the orthodontist and thus results may possibly be obtained that vary largely in quality. Further, such a shortening and roughening of the artificial tooth element by the orthodontist also entails considerable costs.
It is an object of the disclosure to provide an artificial tooth element in which working on the inner part by an orthodontist is not required or is required to only a limited extent.
The artificial tooth element of the present disclosure has an outer part and an inner part. The outer part is the part of the tooth element that is visible in the inserted state, i.e. when the tooth element is inserted into a cavity of a prosthesis base. Consequently, the inner part of the tooth element is the part that is not visible in the inserted state. Regardless of the insertion state, the outer part and the inner part are also defined by the virtual gingiva line. The part of the tooth element, which is the basal part with respect to the virtual gingiva line, is the inner part, and the part which is incisal/occlusal with respect to the virtual gingiva line, is the outer part of the tooth element. The virtual gingiva line, which preferably defines the dividing line between the inner part and the outer part, is preferably circumferential throughout.
According to the disclosure at least parts, in particular all of the surface of the inner part of the artificial tooth element has a defined surface roughness. Thus, the roughness of the surface is created by the manufacturer. As such, the artificial tooth element has a defined surface roughness ex works. Therefore, a reworking of the surface of the inner part by an orthodontist is generally no longer required. Rather, such an artificial tooth element of the present disclosure can be used directly, i.e. fastened, i.e. in particular inserted and glued, in the corresponding cavity of the prosthesis basis.
The virtual gingiva line varies among patients in particular in dependence on the age of a patient. As such, the virtual gingiva line is well suited to define the inner part, which is relevant to the disclosure, and the outer part of the tooth element. Here, it is preferred that the artificial tooth element is roughened or has a defined surface roughness in a region that extends slightly beyond the virtual gingiva line towards the outer part. Thereby, it is ensured that the surface that is relevant to the fastening, i.e. in particular the insertion and the gluing of the artificial tooth element into the cavity, has the necessary roughness. The fact that a small portion of the outer part is also roughened is of no particular importance, since the artificial tooth element will have to be worked, in particular polished, anyway after fastening. This is necessary, e.g., to remove residual adhesive. Thus, it is advantageous that the defines surface roughness is provided on a surface slightly larger than the inner part so as to ensure safe bonding.
The surface having the defined surface roughness is preferably at least the size of the bonding surface and is preferably slightly larger. Preferably, the bonding surface extends slightly beyond the virtual gingiva line into the outer part. Here, a protrusion of 0.5 to 1 mm may exist.
In a particularly preferred embodiment of the artificial tooth element, the surface roughness has an average roughness value Ra of >0 to 30 μm. An average roughness value Ra of >0 to 10 μm, particularly 0.5 to 5 μm, is preferred, with 1 to 4 μm being particularly preferred, and 2 to 3 μm being more preferred.
The average roughness value Ra is determined by:
The roughness depth Rc is preferably in a range of 5 to 25 μm, in particular 5 to 20 μm.
In particular, the lower limit of the arithmetic average roughness value Ra is at least 0.6 μm, preferably at least 0.8 μm and particularly preferred at least 1 μm. Regardless of the lower limit of the arithmetic average roughness value, it is preferred that, as described above, an upper limit is ≤10 μm, in particular ≤5 μm, in particular ≤4 μm, and particularly preferred ≤3 μm.
The visible outer part is preferably smoother than the inner part of the artificial tooth element of the present disclosure. Preferably, the arithmetic average roughness value Ra of the inner side is greater than the arithmetic average roughness value Ra of the outer side. In particular, this value is 30% higher and, as is particularly preferred, 50% higher, so that the inner part is significantly rougher than the outer part.
In a preferred development of the artificial tooth element of the present disclosure, the inner part has a minimum outer radius of at least 0.6 mm. The smallest radius present in the region of the inner part is thus 0.6 mm or more. This is particularly advantageous for forming a cavity in a prosthesis base. It is particularly preferred that the maximum outer radius is at least 1.0 mm and in particular at least 1.25 mm.
It is further preferred that the inner part of the artificial tooth element is formed with an asymmetric shape. In particular, the inner part is formed to be non-rotationally symmetrical. Thereby, an erroneous insertion into the prosthesis base is avoided.
Further, a prosthesis base is provided for producing a prosthesis. The prosthesis base comprises a plurality of cavities, each for receiving one artificial tooth element, as described above and developed in an advantageous manner. The inner surface of the cavities preferably has an at least partly defined surface roughness. In particular, the corresponding inner surface has a size such that it forms at least the bonding surface and thus a defined surface roughness exists in the region of the bonding surface. Preferably, the entire inner surface has a defined surface roughness. It is preferred that the surface roughness of the inner surface of the cavities has an arithmetic average roughness value Ra of >0 to 30 μm. An arithmetic average roughness value Ra of >0 to 10 μm, particularly 0.5 to 5 μm, is particularly preferred, with 1 to 4 μm being more preferred, and 2 to 3 μm being most preferred.
The arithmetic average roughness value Ra of the inner side of the cavity may preferably have values as described above with respect to the surface of the inner part of the artificial tooth element.
In particular for a further improvement of the adhesive bond between the artificial tooth element and the prosthesis it is preferred that the arithmetic average roughness value of the upper side of the cavity is ±50% of the arithmetic average roughness value of the surface of the inner part of the artificial tooth element.
Here, the individual cavities are preferably formed with respect to a direction of insertion of the corresponding artificial tooth element into the prosthesis base such that the cavities are free from undercuts. Thereby, a simple arrangement of the artificial tooth elements in the corresponding prosthesis base is possible.
The individual cavities of the prosthesis base are preferably formed to be complementary to the respective inner part of the artificial tooth element to be inserted correspondingly. Thereby, a gap of a constant width is formed between a respective cavity and the inner part of the associated tooth element. This ensures a safe fastening of the artificial tooth element in the prosthesis base. Moreover, the congruence between the real prosthesis and the planned virtual prosthesis is thus very high, so that the end use has to do little reworking, if any. In particular the occlusion plane and function correspond very precisely to the plan and only have to be reworked a little, if at all.
In a particularly preferred development of the prosthesis base, the cavity has a minimum inner radius equal to or larger than the minimum outer radius of the inner part of the artificial tooth element. If the inner part of the artificial tooth element has an outer radius of e.g. a minimum 0.6 mm or more, the cavity exclusively has radii that are at least 0.6 mm or larger. This has the advantage that, when forming the cavities, tools such as a milling tool can be used, whose milling head or the like has a corresponding working radius. With a radius of at least 0.6 mm, a milling head with a diameter of 1.2 mm can thus be used. For the forming of smaller radii, a smaller milling head would have to be used. Using small milling heads or corresponding tools prolongs the time for forming a cavity and results in a shorter service life of the tool. Therefore, it is further preferred that the minimum inner radius of the cavity is in particular equal to or greater than 1.0 mm and, as is particularly preferred, equal to or greater than 1.25 mm.
In particular when asymmetric, specifically non-rotationally symmetrically shaped artificial tooth elements are used, the cavities are also formed asymmetrically, specifically non-rotationally symmetrically, in a preferred embodiment. This has the essential advantage that a clear association between the respective artificial tooth element and the corresponding cavity, as well as a clear positional definition of the corresponding tooth element in the cavity are defined in a clear and unambiguous manner.
Therefor, it is particularly preferred that the cavities each have a different shape so that an unambiguous association between the artificial tooth element and the cavity exists. As such, an erroneous insertion is excluded.
Moreover, it is preferred that the cavities are formed, in particular have a depth such that an inserted artificial tooth element has a defined tooth height.
Further, it is particularly preferred, especially also for aesthetic reasons that the virtual gingiva line of the artificial tooth element coincides at least partly, in particular completely, with the cavity edge in the inserted state and the two edges overlap, in particular completely.
A particularly suitable method for manufacturing a prosthesis base, as well as artificial tooth elements is described in WO 2018/036853.
The disclosure will be explained in more detail hereinafter with reference to a preferred embodiment and to the accompanying drawings.
In the Figures:
The virtual gingiva line 10 is illustrated in the example of a tooth element shown in
The virtual gingiva line is in the undercut-free region. The undercut-free region is defined by a line 16. Here, the line 16 defines the border of the undercut-free region in the direction of placement or insertion. In
The line 16, which is arranged within the outer part 12 with respect to the virtual gingiva line 10 and is spaced from the virtual gingiva line 10, can further define a border of the surface 11 having a defined roughness. In a preferred development, the surface 11 having a defined roughness thus not only includes the surface in the region of the inner part 14, but also extends into the outer part towards or up to the line 16.
A prosthesis base 20 (
Since it is particularly preferred that the inner part 14 of the tooth element has no undercuts in a direction of insertion 26 (
The cavity 22 is formed to be complementary to the inner part, so that an exact positional definition of the tooth element in the cavity 22 is given. By a complementary design of the inner part 14 and the cavity 22, it is further possible to form—if necessary—a bonding gap 28 (
In
For a complete manufacture of a prosthesis, a plurality of cavities is provided in the prosthesis bas 20 (
| Number | Date | Country | Kind |
|---|---|---|---|
| 19205897.2 | Oct 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/079498 | 10/20/2020 | WO |
