Patent Application
20110163470
The invention refers to a system for creating a data record describing a dental prosthesis part, a system for the production of a dental prosthesis part, associated methods as well as a data record.
For the production of dental prosthesis parts by means of CAD/CAM methods it is known to create a model of a dental prosthesis part on a computer, the shape of this dental prosthesis part being stored in a data record. By means of such a data record, a dental prosthesis part can be manufactured in automated form.
These data records describe the desired shape of the dental prosthesis part so that this desired shape can be produced by the respective production methods.
However, it is desirable for special dental prosthesis parts and for some production methods that besides the information concerning the shape other information is also usable.
According to one embodiment of the invention, a system is provided for creating a data record having entries with respect to a plurality of elements, wherein these elements describe the shape or the surface of a dental prosthesis part. The elements can for instance be points or surface elements of the surface or also volume elements. For each such entry also one, two or more attributes are listed. Besides such entries with elements for which attributes are listed it is also possible that the data record comprises entries with respect to a plurality of elements for which, however, attributes are not listed. However, respective attributes can also be listed for all elements of the data record.
The system preferably comprises hardware and/or software components for designing a dental prosthesis part. For this purpose, a scanner can also be provided that can scan a model of a remaining tooth portion or a remaining tooth portion itself so that by this a data record is provided on the basis of which a data record describing the dental prosthesis part can be designed.
Furthermore, the system preferably comprises hardware and software components by means of which a plurality of elements can jointly be selected and certain attributes can jointly be associated to these elements. It is also possible that the allocation of attributes takes place in an automated manner in that a model is for instance automatically analyzed as to certain portions, and respective attributes are set automatically. Attributes can also be set manually in that when designing the dental prosthesis part in a computer-assisted manner respective portions of the dental prosthesis part are produced or provided with the respective attributes. Elements can also be selected for instance by means of a mouse or another operating device, and one or several attributes can then be allocated to these elements by respective instructions. For this purpose an area can be marked or selected in the visually shown model of the dental prosthesis part by a respective input device. The input could also be made by a selection of elements by means of certain criteria. The selection can also be made in a tabular illustration of the data record.
The attributes can for instance define a product accuracy, a material or the color for an element.
A system for producing a dental prosthesis part can for instance be a laser sintering device, however it can also be another device, such as generally a rapid prototyping device. Such a system can read-in a data record, wherein information concerning the attributes are also read in. Such attributes can be processed for controlling the production process. The system can for instance react with one or several predetermined actions on one or several attributes.
Preferably, attribute values are associated to other geometric elements, such as lines, wherein these geometric elements are used in the production process. Such other geometric elements can for instance be produced by a transfer of the shape defined by the surface elements to another geometric illustration required for production.
The data record is characterized in that not only a plurality of elements are entered that describe the surface or shape of the dental prosthesis part, but also by the fact that an attribute is listed for each element.
For instance more than 1,000, 5,000 or 10,000 entries can exist that describe elements. Attribute values are set for each such element.
Thus, entries can also exist in which no attributes are set. These can also be more than 1,000, 5,000 or 10,000 entries.
The data record can exist in the form of an stl format, a wmf format or any other format for storing a three-dimensional shape. Stl or wmf formats are detected by commercially available rapid prototyping devices.
The attributes are preferably stored in 2 bytes. The data to the elements in an entry can preferably occupy 48 bytes.
Preferred embodiments of the invention are explained by means of the enclosed Figures:
a and 3b are schematic illustrations of the surface of a dental prosthesis part for use in a laser sintering process;
a and 4b further illustrate schematically various surface elements of a dental prosthesis part during a production process; and
With a network of such surface elements any three-dimensional shape can be approximated or shown.
For storing this model, the data of the individual triangular surface elements is stored. This data for instance comprises the X, Y and Z coordinates of the three corner points. These are for surface element 2 e.g. points P1, P2 and P3.
Furthermore, a normal vector N with its X, Y and Z component is stored for this surface element. This normal vector can be standardized to 1. The normal vector usually serves for defining an orientation of the surface element, e.g. to distinguish the inner from the outer side of the surface.
If each of the X, Y, Z coordinates of the three corner points as well as the X, Y, Z component of the normal vector N is stored with 4 bytes each, a total of 48 bytes are required for this purpose. This part of the data of an entry in a data record is shown in
Particularly, the STL data formal shall be listed in the following:
The file is therefore substantially composed of facets (triangular surface elements), wherein each facet has 50 bytes of memory space available, from which 48 bytes are used for data of the normal and the corner points and 2 bytes are not used. In these two bytes attribute values can be stored and this for each individual facet.
Different attributes A1, A2 can be set for the surface elements 2 to 5. This is shown in
As can be seen in
Each attribute can be stored in its own byte. However, a plurality of attributes can also be stored in one byte or several attributes can be distributed to several bytes, as for instance 3 or 4 attributes to two bytes.
The attributes for an entry in a data record are indicated in
Such an entry 45 is provided for each surface element 2 to 5.
If none of the attributes is to be set for a surface element, the data field provided for this purpose remains empty (e.g. filled by zeros).
As can be seen, the surface 16 formed by the steps differs from the shape determined by the surface element 15′. To reduce these deviations it is for instance possible to carry out the laser sintering process with thinner material applications so that smaller steps 18 result, as shown in
By use of the attributes, the production process during laser sintering can for instance be modified in that depending on the desired production accuracy differently high steps are generated or differently thick material applications take place that are subsequently solidified by laser sintering.
As shown in
a shows a section along a plane of the production process. The dental prosthesis part has an outer surface 29 and an inner surface 30 whose sections form straight line pieces with the drawing layer. The straight line pieces collide on the corner points 25, 26, 27, 28. The corner points 25 to 28 result from the section of a plane 20 with the triangular surface elements, as shown in
The attribute(s) of the surface element 21 can be associated to the line piece between the corner points 25 and 26. The attribute(s) of the surface element 22 can be associated to the line piece between the corner points 26 and 27, and the attribute(s) of the surface element 23 can be associated for the corner points 27 and 28, etc.
An attribute can also be associated to the corner points themselves. On the one hand it is conceivable that two overlapping corner points are provided instead of one corner point, wherein each corner point is associated to one line each. The attribute of the associated line is associated to each of these corner points. If, however, a corner point between two line pieces is associated to the two line pieces, either one of the two attributes can be selected, wherein respective predefined rules can be used, or a mean value can be formed, if the type of attribute values makes this possible.
Since the outer side 29 and the inner side 30 are defined by different surface elements, different attributes can be used in the same plane for the outer side and for the inner side.
A computer system 40 is shown in
The system 40 further preferably comprises a scanner 42 by means of which a remaining tooth portion can be scanned. The data obtained thereby can serve as a basis for a model 44 of a dental prosthesis part.
The data record 43 comprises various entries 45, wherein each entry comprises a portion 46 that defines elements defining the surface or shape of a dental prosthesis part, as well as a part 47 that defines the attributes for such elements.
On the right-hand side of
The focus 50 is located on the material surface 52, wherein further material 51 is applied onto this surface 52 in a layered manner and is there locally solidified by the laser beam 49. For this purpose the laser beam 49 or also a receiving trough 53 can be displaceable in all three spatial directions (see reference numeral 54). The laser beam 49 can also be movable along the surface 52 and the trough can be movable in a direction perpendicular thereto or vice versa.
By controlling the relative arrangement of the laser 49 with respect to the trough 53, parts shaped in any manner can be laser-sintered.
The material 51 used can for instance be gold dust or possibly a sinterable ceramic material.
A controller 48 is provided to control the relative arrangement of the laser 49 and the trough 53. This controller can read-in a data record 43, wherein during read-in the attribute data 47 is also used for producing the dental prosthesis parts. This relative control between the laser and the trough 53 can be influenced by the attributes.
The consideration of the attribute data can for instance lead to the fact that, as shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 028 748.2 | Jun 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/004281 | 6/15/2009 | WO | 00 | 2/4/2011 |
