BLANK AND METHOD FOR PRODUCING A DENTAL RESTORATION WITH PARTITION SEGMENT AND RESTORATION SEGMENT

Abstract

The blank has a restoration segment (4), a holder (2), and a partition segment (3) that connects the holder (2) to the restoration segment (4). The material of the partition segment (3) visually differs from that of the restoration segment (4). In preparation for machining, in the context of CAD/CAM machining, the outer shape of the workpiece (6) to be produced is fitted into the restoration segment (4) such that a smooth surface of the outer shape comes to lie in the interface plane (5) between the segments. The blank is then worked mechanically in order to create the outer shape. A partition pin (3b, 3c) remains between the holder (2) and the restoration segment (4) and is removed. A partition-pin-base (13) remaining in the restoration segment (4) can then be removed manually. A color marker simplifies this work step.

Claims

1. A blank for preparing a dental restoration by means of automated abrasive machining in a machining device, wherein the blank comprises a restoration segment of a machinable tooth replacement material as well as a holder for clamping the blank in the machining device, wherein a partition segment of a machinable partition segment material is arranged between the holder and the restoration segment, wherein the partition segment material differs visually from the tooth replacement material.

2. The blank of claim 1 wherein the partition segment material differs from the tooth replacement material in its pigmentation only.

3. The blank of claim 1 wherein the partition segment material is of a material different from the tooth replacement material, and in particular wherein the restoration segment is of a ceramic and the partition segmenter of a polymeric material.

4. The blank of claim 1 wherein the partition segment is glued to the restoration segmenter and/or the holder.

5. The blank of claim 1 comprising an optical marker, which marks a location of a proximal contact to be generated at an interface plane between the partition segment and the restoration segment.

6. The blank of claim 5 wherein the marker is located in a core axis of the blank, which core axis forms a symmetry axis of the restoration segment, in particular of a whole blank.

7. The blank of any of claim 5 wherein the marker is formed by a coloring arranged in the partition segment, in the restoration segment and/or at the interface plane.

8. The blank of claim 5 wherein the marker extends, perpendicularly to the interface plane, from the interface plane through at least a part of the partition segment and/or the restoration segment, in particular over a depth of at least 0.1 mm, in particular of at least 1 mm.

9. The blank of claim 8 wherein the marker extends through the whole restoration segment, and in particular wherein the marker is darker than a rest of the restoration segment.

10. The blank of claim 9 wherein the marker is surrounded, in the restoration segment, by several regions of different colors.

11. The blank of claim 5, wherein the marker extends as a zone over a region having a diameter of at least 1 mm parallel to the interface plane.

12. The blank of claim 1 wherein the partition segment has a same contour as the holder and/or the restoration segment.

13. The blank of claim 1 wherein the partition segment is of a material comprising glass, plastics, in particular polymers, and ceramics.

14. The blank of claim 1 wherein the holder and the partition segment are of a single piece.

15. The blank of claim 1 wherein a coding is arranged on or in the partition segment, in particular a coding formed by a coloring, a surface relief and/or an electronically readable data carrier.

16. The blank of claim 1 wherein an adhesive bonding medium provided at an interface plane between the restoration segment and the partition segment differs in color from the restoration segment as well as from the partition segment.

17. The blank of claim 1 wherein the partition segment has a color different from the restoration segment.

18. The blank of claim 1 wherein a first adhesive connection is arranged between the partition segment and the restoration segment and/or wherein a second adhesive connection is arranged between the partition segment and the holder.

19. The blank of claim 18 wherein the first and/or the second adhesive connection is of a material different from the partition segment.

20. The blank of claim 18 wherein the first and/or the second adhesive connection has a thickness of at least 2 m and at most of 125 m.

21. The blank of any claim 1 wherein a thickness of the partition segment along a direction between the holder and the restoration segment is at least 0.5 mm, in particular at least 1 mm, and/or no more than 3.0 mm.

22. The blank of claim 1 wherein a part of a holder-sided interface plane of the restoration element is mechanically accessible.

23. The blank of claim 1 wherein the partition segment has, in a direction perpendicular to a core axis of the blank, a smaller diameter than the restoration segment.

24. The blank of claim 1 wherein the partition segment is set back at least at one location in order to form a recess between the holder and the restoration element.

25. A method for machining a blank for manufacturing a workpiece, wherein said blank comprises a restoration segment of a machinable tooth replacement material, a holder for clamping the blank in a machining device, a partition segment of a machinable partition segment material arranged between the holder and the restoration segment, wherein the partition segment material differs visually from the tooth replacement material and wherein the holder and the partition segment are of a single piece, wherein said method comprises the steps of: providing a data set describing an outer shape of the workpiece, numerically fitting the outer shape of the workpiece into the restoration segment such that a surface of the outer shape comes to lie, at a contact, in particular a proximal contract, in an interface plane between the partition segment and the restoration segment, mechanically removing material from the restoration segment up to the outer shape, excluding a partition-pin-base around the contact or proximal contact, removing the partition segment from the restoration segment, machining the workpiece at said partition-pin-base.

26. The method of claim 25 wherein before, after or during mechanically removing material from the restoration segment, a mechanical removal of material from the partition segment occurs as well, namely such that a partition pin forms between the holder and the partition-pin-base of the restoration segment.

27. The method of any of claim 25, wherein the removal of at least part of the partition segment occurs by means of chemically dissolving the partition segment, by means of burning the partition segment, by means of melting the partition segment, splitting a bond between the partition segment and the restoration segment.

28. The method of any of claim 25 wherein a position of a holder-sided interface plane of the restoration element is sampled in order to fit the outer shape into the restoration segment.

29. A machining device for carrying out the method of claim 25 with an attachment device for attaching the holder of the blank, at least one abrasive machining tool for machining the restoration element and the partition segment, drives for moving, during machining, the blank and the tool in respect to each other, a control unit adapted to carry out the steps of the method.

30. A method for machining a blank for manufacturing a workpiece, wherein said blank comprises a restoration segment of a machinable tooth replacement material, a holder for clamping the blank in a machining device, a partition segment of a machinable partition segment material arranged between the holder and the restoration segment, wherein the partition segment material differs visually from the tooth replacement material and wherein the holder and the partition segment are of a single piece, wherein said method comprises the steps of the steps of: providing a data set describing an outer shape of the workpiece, numerically fitting the outer shape of the workpiece into the restoration segment such that a surface of the outer shape comes to lie, at a contact, in particular a proximal contract, in an interface plane between the partition segment and the restoration segment, mechanically removing material from the restoration segment up to the outer shape, excluding a partition-pin-base around the contact or proximal contact, removing the partition segment from the restoration segment, machining the workpiece at said partition-pin-base.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Further embodiments, advantages and applications of the invention are given in the dependent claims as well as in the now following description with reference to the figures, wherein:

[0060] FIG. 1 shows a schematic representation of a dental CAD/CAM blank with an intermediary partition segment between the holder of the block and the restoration segment, and a semi-perspective representation of an inlay CAD-construction for subtractive CAM-manufacturing,

[0061] FIG. 2 is a schematic view, from the occlusal side, of an inlay and of the partition pin at the end of the subtractive CAM-milling process with a typical breaking fissure in the partition pin,

[0062] FIG. 3 is a schematic partial view, from the occlusal side, from FIG. 2 with the rest of the partition pin on the partition-pin-base of the proximal surface of the inlay,

[0063] FIG. 4 is a schematic representation, from the occlusal side, of the partition parts of the blank with the partition segment after the fracture of the partition pin and after detaching the rest of the partition pin from the partition-pin-base on the proximal surface of the inlay with a color coding of the blank extending from the region of the proximal partition-pin-base throughout the block,

[0064] FIG. 5 is a schematic view, from the occlusal side, of the CAM-manufactured inlay with the color-coded partition-pin-base still present, wherein the color coding extends longitudinally through the inlay,

[0065] FIG. 6 is a schematic view, from the occlusal side, of the inlay inserted into the tooth with the color-coded central contact surface of the proximal contact precisely in the designed position and the still complete partition-pin-base,

[0066] FIG. 7 is a schematic representation of the proximal surface with the position of the color-coded central contact surface of the proximal contact accurately according to the design and with the outer boundary lines of the partition-pin-base,

[0067] FIG. 8 is a schematic representation of the inlay inserted into the dental cavity with the position of the central proximal contact on the side of the partition pin exactly according to the design, after the controlled abrasive removal of the surrounding parts of the partition-pin-base to the level of the proximal surface,

[0068] FIG. 9 is a schematic representation of a blank for the crown of a posterior tooth with a partition segment and with a central color coding extending through the restoration segment starting from the region of the partition-pin-base and, in addition and parallel thereto, surrounding zones of color, translucence and opacity,

[0069] FIG. 10 is a further embodiment of the blank block in which the surface on the side of the holder of the restoration segment is accessible for sampling its position, and

[0070] FIG. 11 is a machining device for carrying out the method.

MODES FOR CARRYING OUT THE INVENTION

[0071] Dental CAD/CAM Blank Block, Partition Segment

[0072] FIG. 1 shows the schematic representation of an embodiment of a dental CAD/CAM blank 1, for manufacturing dental restorations, with a holder 2, a partition segment 3, and a restoration segment 4, which form a mechanical unit and are clamped like this in a machining device (for grinding and/or milling). During this, holder 2 is used for the fixation in the machining device.

[0073] The restoration segment 4 consists, e.g., of one of the machinable dental restoration materials mentioned above,known to the skilled person.

[0074] Partition segment 3 consists of a partition segment material, e.g. according to one of the examples mentioned above.

[0075] Holder 2 consists, e.g., of metal. It forms a rod that can be clamped in the machining device.

[0076] The holder 2, the partition segment 3, and the restoration segment 4 are connected to each other at an interface plane 5, e.g. bonded by means of gluing. The respective first adhesive connection between the restoration segment 4 and the partition segment 3 is designated by reference number 33 in FIG. 1, and the second adhesive connection between the holder 2 at the partition segment 3 by reference number 34.

[0077] Advantageously the thickness of the adhesive connections 33, 34 is at least 2 m and/or at most 125 m.

[0078] The adhesive connections 33, 34 advantageously consist of material different from the partition segment. In particular, this allows to better adapt the material for the partition segment to its requirements regarding machinability and stability.

[0079] The workpiece to be formed, such as an inlay 6 with three surfaces, is represented in semi-perspective manner with its constructive plan in the block. Its proximal surface 7 with a contact region 8 is shown. In the complete state, the inlay 6 will contact the neighboring tooth in a proximal contact, whose center is designated by reference number 9.

[0080] For the shaping step of machining, the data set describing the outer surface of the inlay 6 to be designed, with its contact region 8 and the proximal contact 9 forming the contact center, is numerically brought to coincide with the bounding surface 5 of the restoration segment 4 at the interface plane 5 with the partition segment 3.

[0081] The center of proximal contact 9 at the proximal surface 7 of the inlay is preferably positioned to coincide with a core axis 10 in the center of the partition segment 3. The core axis 10 also forms the central axis of restoration segment 4.

[0082] FIG. 1 further shows an encoding 30, which, as mentioned, can be a coloring (a print), the surface relief, or an electronically readable data carrier.

[0083] FIG. 2 shows, in a schematic representation, a view on the occlusal surface 6a of the inlay 6, which has been formed from the restoration segment 4 by removing material in the CAM process.

[0084] The partition segment 2 has been reduced, by means of subtractive machining, to a residual layer 3a on the side of the holder and to a partition pin 3b, 3c. The partition pin 3b, 3c connects the residual layer 3a on the side of the holder with the remaining restoration segment 4.

[0085] The partition pin 3b, 3c is broken by cutting. FIG. 2 shows a typical fracture line 11 that is formed in this way in occlusal-cervical direction.

[0086] The core axis 10 marks, with its core end face 12, the transition to the center of proximal contact 9 on the proximal surface 7 of the inlay.

[0087] The adhesive connection 33 at the interface plane 5 provides the adhesion between the rest of the partition pin 3c and the surface of the partition-pin-base 13 on the proximal surface 7 of inlay 6. This partition-pin-base 13 designates the part of restoration segment 4 that is adjacent to the rest 3c of the partition pin and still projects beyond the desired shape of the workpiece to be formed.

[0088] FIG. 3 schematically shows a partial view of inlay 6, from the occlusal side, with the partial contour of the proximal surface 7, on which partition-pin-base 13 formed from the restoration segment 4 carries the rest 3c of the partition pin.

[0089] At the interface plane to the glue joint 14, the core axis 10 of the rest 3c of the partition pin is different in color and marks, with its core-end-surface 12, the transition to the proximal contact 9 on the proximal surface 7 of the inlay 6.

[0090] The limit points 13a and 13b mark the outer contour, remote from the proximate contact, of the partition-pin-base 13 on the anatomically shaped proximal surface 7 of the workpiece to be manufactured.

[0091] FIG. 4 shows separate elements of a blank with: the holder 2, the remaining layer of partition segment 3a, with the fractured stub 3b of the partition pin and the fracture line 11, the rest 3c of the partition pin removed from the restoration segment 4, with the core axis 10, the core end surface 12, the center of the a proximal contact 9, the interface plane or bounding surface 5 of the restoration segment 4, the anatomic contour of the proximal surface 7 of the inlay 6, the inner and outer contour limits 13a and 13b of the partition-pin-base 13.

[0092] Further, FIG. 4 shows, as a variant, visually distinguishable color zones 4a, 4b, 4c, which extend over the whole length of the restoration segment 4 starting from the partition-pin-base 13 and the interface plane 5. These color zones are embedded in in the restoration segment 4 of the blank by the manufacturer. They are advantageously symmetrical about the core axis of the blank block 1.

[0093] By marking the surface of the partition-pin-base 13 with the color zones 4a, 4b, 4c, the manual, abrasive removal of the partition-pin-base 13 from the anatomic proximal surface 7 between the proximal contact 9 and the outer circumference 13 be can occur in a controlled manner.

[0094] FIG. 5 shows a view, from the occlusal side, of the inlay 6 formed from the restoration segment 4, with the interface plane 5 and the partition-pin-base 13 of the inlay 6 between the inner circumference borders 13a and 13a and the outer circumference borders 13b and 13b, between which the color layers 4a, 4b, and 4c are located.

[0095] FIG. 6 schematically shows the inlay inserted into the tooth 14 for trial, with the contours 15 and 16 of the neighboring teeth. The accurately constructed proximal contact is located in the position of the former interface plane 5.

[0096] The tips of the oral cusp 14a and the buccal cusp 14b are shown. Usually, the still present partition-pin-base 13 does not interfere with the fit, even though it still projects over the surface as shown by positions 13a and 13b.

[0097] FIG. 7 schematically shows the proximal surface 7 of the inlay 6 and the cusps 14a and 14b, i.e. the view of the machined restoration segment 4 along the core axis onto the proximal surface 7.

[0098] The outer contour 13b of the partition-pin-base 13 marks the position and size of the partition-pin-base 13 with the central, contacting zone 4a and the color codings 14b and 4c remote from the contact.

[0099] The circumference 13b of the base forms an outer limit of the color coding 4c against the material of the rest of the restoration segment 4.

[0100] The color-coded regions 4b and 4c remote from the contact and beyond the region 4a can be removed manually and abrasively in a controlled manner using the visual distinction of the color layers.

[0101] FIG. 8 shows the proximal contact of the inlay in the tooth 14 after removing the partition-pin-base 13, with the neighboring tooth 15 at the position of the previous interface plane 5 between the partition pin 3 and the restoration segment 4. The marking of the tips of the cusps 14a and 14b can be used for orientation.

[0102] Below the occlusal surface, the color coding of the previous partition-pin-base extends to the mesial neighboring tooth 16 and serves to tinge the occlusal surface.

[0103] FIG. 9 shows the schematic view of a blank 1b for manufacturing a crown in the region of the posterior teeth as seen from the front surface 19 of the restoration segment 4.

[0104] The partition segment 3 and the holder 2 are located adjacent to the remote side. The designed external contour of a crown 18 for a posterior tooth is schematically shown in the restoration segment 4.

[0105] Again, this crown design is fitted numerically into the restoration segment 4 in such a manner that it touches, according to the method described here, with its proximal contact 9, the interface plane 5 between the restoration segment 4 and the partition segment 3.

[0106] The outer contour line 13b designates the border of the contact-free zone of the partition-pin-base 13. The color coding of the partition-pin-base 13 can again extend along the center of the restoration segment 4 along the longitudinal axis of the blank, i.e. the core axis, and the mesio-distal crown axis, all the way to the front surface 19, where it is visible as the core zone 4abc.

[0107] In order to polychromatically modify the aesthetics of the crown as compared to monochrome embodiment of the restoration segment 4, the color-coded core zone 4abc can consist of opaque dentin material.

[0108] The core zone 4abc can be complemented by means of color zones of different color and brightness, on each side, e.g. as follows. [0109] In the cervical row: dark enamel material 22, dark dentin material 23, dark enamel material 24. [0110] In the central row: medium-shade enamel material on both sides 21, 25 central dentine 4abc. [0111] In the occlusal row: light enamel material on both sides 20, 26, central medium-shade enamel material.

[0112] By surrounding with color zones of different levels of color and opacity, the partition pin is visually even more distinct during its manual abrasive removal, and it further allows a polychromatic design of the restoration.

[0113] FIG. 10 shows a further embodiment of the blank. In this embodiment, part of the holder-sided (i.e. facing the holder 2) interface plane 5 of the restoration segment 4 is laid open, i.e. not covered by the partition segment 3, and mechanically accessible. This has the advantage that, in a machining device, the position of this interface plane 5 can be measured, which, as mentioned further below, is advantageous while machining the blank.

[0114] Such an embodiment is e.g. possible by giving the partition segment 3, in its direction perpendicular to the core axis 10, a smaller diameter than the restoration segment 4, in particular in at least one direction perpendicular to the core axis 10.

[0115] It is conceivable, as shown in FIG. 10, for the partition segment 3 to be recessed in at least at one location in order to form a recess 32 between the holder 2 and the restoration segment 4, where the interface plane 5 is accessible for measurement.

[0116] Manufacturing

[0117] While manufacturing the blank, the partition segment 3 can, for example, first be connected to the holder, by bonding and/or mechanically, and then be glued to the restoration segment 4.

[0118] Manufacturing the blank can also occur in a first step by bonding or mechanically connecting the restoration segment 4 with an industrially pre-manufactured transparent and/or colored partition segment 3 of a suitable ceramics, polymeric, composite, hybrid, or glass material, whereupon, in the second step, the blank block is connected, on the side of the partition segment 3, to the holder 2.

[0119] Manufacturing the blank block can also be carried out by means of consecutive compression of ceramics granulates by using different colors and/or different transparency as well as opacity, for the restoration segment 4 and the partition segment 3.

[0120] If the visually different partition segment 3 and restoration segment 4 are manufactured separately, they can, in particular, be connected to each other by means of glass solder and then, as a blank block (consisting of the partition segment and restoration segment) be glued to the holder 2.

[0121] The partition segment 3 can also be manufactured from a non-costly, non-dental separating-segment-material, which has suitable properties for milling and stability.

[0122] If a material with suitable elastic module is used, the partition segment 3 can contribute to dampening the vibrations that are generated during machining of the ceramics, to the silent operation of the machining, and to a reduction of the stress of thin material parts

[0123] The holder 2 and the partition segment 3 can be formed as an integral part of a single piece if the material fulfills the requirements regarding stability, precise clamping in the milling machine, and machinability at the same time. In this case, the holder is axially extended, in respect to the border surface of the restoration segment, by the thickness of the partition segment.

[0124] Alternatively thereto, the holder 2 and the partition segment 3 can be of different materials. For example, the holder 2 can be of a metal.

[0125] Machining

[0126] Machining of the blank occurs, as mentioned, in a machining device, which has at least one abrasive tool for abrasively machining the blank. For manufacturing the workpiece, the respective method executes the following steps: [0127] Providing a data set defining an outer shape of the workpiece, [0128] Numerically fitting the outer shape into the restoration segment 4 such that a surface of the outer shape comes to lie in a contact, in particular a proximal contact 9, in an interface plane 5 between the partition segment 3 and the restoration segment 4. [0129] Mechanically removing material of the restoration segment 4 up to the fitted outer shape, with the exception of a partition-pin-base around the proximal contact 9, [0130] Removing the partition segment 3 from the restoration segment 4, and [0131] Machining the restorative workpiece 6 in said partition-pin-base.

[0132] Advantageously, the position of the holder-side interface plane 5 of the restoration element 4 is sampled in the machining device, namely the position in the direction of the core axis 10. For this purpose, interface plane 5 should, as mentioned above, be mechanically accessible. The measurement of this position is advantageous because it allows to position the outer shape of the workpiece more accurately at the interface plane 5, thus the outer shape can be fitted precisely into the restoration segment. The machining errors of the partition segment 3 and the adhesive connections 33, 34 are eliminated by means of this calibration.

[0133] Sampling the position of the holder-sided interface plane 5 is advantageously carried out by driving a machining tool of the machining device, from the side of the holder 2 against the interface plane 5 until a mechanical contact occurs. The position of the tool upon this contact defines the position of the interface plane 5.

[0134] A machining device 40 for carrying out the method is shown in FIG. 11. It has an attachment device 41 at which the holder 2 of the blank 1 can be attached, at least one abrasive machining tool 42 for machining the restoration element 4 and the partition segment 3. Further, drives 43 are provided for moving, during machining, the blank 1 and the tool 42 in respect to each other.

[0135] The machining device 40 further comprises a control unit 44, which (e.g. by means of suitable control programs) is adapted to carry out the steps of the described machining method by controlling the components of the machining device 40 accordingly.

[0136] Notes

[0137] As mentioned, the partition segment 3 can have the same circumference as the holder 2 and/or the restoration segment 4. Alternatively, the partition segment 3 can, in a direction perpendicular to the core axis 10, also have a smaller diameter than the restoration segment 4.

[0138] In this manner, the time for machining the partition segment 3 can be reduced or even eliminated.

[0139] The partition segment 3 can consist of any material that differs from the restoration segment 4 in its color and/or opacity and translucence which, if applicable, fulfills the requirements for a precise subtractive machining and stability of the material used in the restoration segment.

[0140] The adhesive bonding compound (adhesive, e.g. glass solder) between the restoration segment 4 and the partition segment 3 of the blank differs advantageously in its color from the restoration segment 4 as well as from the partition segment 3, e.g. by being colored with strong pigments. In this way, the interface plane between the two segments is marked and processing is made easier.

[0141] While, in the present application, preferred embodiments of the invention are described, it is to be pointed out that the invention is not limited thereto and can also be carried out in different manner within the scope of the following claims.