Dental instrument for processing ceramic crowns

Abstract

Dental instrument for processing ceramic crowns, including: - a shaft (2) for clamping the dental instrument into a drive, and - a diamond-studded work area (3) for processing the ceramic crown, - wherein a binder (6) is applied to the work area (3), - wherein the diamonds are partly arranged and fixed in the binder (6) and partly protrude over an outer surface of the binder (6), and - where the diamonds are fractured diamonds (5).

Description

[0001] The present invention relates to a dental instrument for processing ceramic crowns, in particular crowns made of zirconium oxide (ZrO2) and in particular for separating such ceramic crowns.

[0002] For approximately 15 years, all-ceramic crowns, bridges, and the like have been increasingly used as dental prostheses. Unlike ceramic-veneered metal crowns, all-ceramic crowns are made exclusively of ceramic, particularly zirconium oxide. One problem with all-ceramic crowns arises when they need to be removed. Because the ceramic (ZrO2) used is very hard, the dental instruments used for this purpose clog up very quickly. This is especially true when entire all-ceramic bridges have to be removed. For example, DE 199 08 507 A1 discloses the arrangement of diamond grains on the surface of a grinding head for grinding purposes in dental instruments. However, the dental instrument disclosed therein is only suitable for machining tooth enamel, which has a significantly lower hardness than all-ceramic crowns.

[0003] It is therefore an object of the present invention to provide a dental instrument for machining all-ceramic crowns with excellent wear behavior while being simple and cost-effective to manufacture.

[0004] This object is achieved by a dental instrument having the features of claim 1. The subclaims show preferred developments of the inventions.

[0005] The dental instrument according to the invention with the features of claim 1 has the advantage that the dental instrument has a very low wear rate and is therefore ideally suited for processing ceramic full crowns, particularly those made of zirconium oxide. The dental instrument of the invention exhibits significantly better cutting performance than comparable dental instruments. Thermal stress on the dental instrument during the processing of ceramic full crowns can also be significantly reduced, which also contributes to an extended service life of the dental instrument.

[0006] This is achieved according to the invention in that the dental instrument according to the invention for machining ceramic full crowns has a shaft for clamping into a drive and a working area covered with diamonds for machining the ceramic crown. The working area has, in particular, a core which is formed integrally with the shaft, wherein a binding agent is applied to the core. The diamonds are partially arranged in the binding agent and thereby fixed, and partially protrude beyond an outer surface of the binding agent. The diamonds in this case are fracture diamonds. Fracture diamonds are produced from larger diamonds using a breaking process. The fracture diamonds used according to the invention are thus deliberately produced by breaking larger diamonds. The fracture diamonds have a large number of sharp edges and corners, whereby the fracture diamonds are nevertheless lumpy diamonds.Due to the large number of sharp edges and corners that protrude above the bonding agent of the dental instrument, hard materials such as ceramics can be excellently processed and, in particular, separated in order to remove a dental ceramic or a bridge for a patient as quickly and effectively as possible.

[0007] Preferably, the fracture diamonds in the working area are synthetic fracture diamonds. Synthetic fracture diamonds are produced by crushing synthetically produced diamonds. Theoretically, natural diamonds could also be crushed for the invention, but this is too expensive for dental instruments, so synthetic diamonds are preferably used to produce the fracture diamonds.

[0008] More preferably, the fracture diamonds have a maximum length L and a maximum width B perpendicular to the maximum length L, wherein a ratio V of maximum length L to maximum width B, V=L / B, is in a range from 1.00 to 2.10, in particular in a range from 1.20 to 1.80 and more particularly in a range from 1.40 to 1.60.

[0009] Particularly preferably, the maximum length L of the fracture diamonds is in a range from 85 µm to 190 µm, in particular in a range from 100 µm to 170 µm, more particularly in a range from 140 µm to 150 µm. Preferably, a maximum width B of the fracture diamonds is between 70 µm and 125 µm, in particular between 80 µm and 120 µm, and more particularly between 100 and 110 µm.

[0010] A particularly long service life when machining hard ceramic materials can be achieved if the dental instrument has a depth of embedding of the broken diamonds in the bonding agent such that 60% to 70% of the volume of the broken diamonds is embedded in the bonding agent. This means that between 30% and 40% of the volume of the broken diamonds protrudes from the surface of the bonding agent of the dental instrument and can be used for machining ceramic crowns.

[0011] Particularly preferably, the fracture diamonds have a projection above a surface of the binder in a range of 44 µm to 86 µm, and in particular in a range of 55 µm to 75 µm, and more particularly 60 µm to 70 µm. This height of the fracture diamonds, which projects above the binder, ensures that cutting operations can also be carried out, particularly on ceramic crowns.

[0012] Further preferred is a coverage density of the broken diamonds on the bonding agent in a range of 45% to 61%, and in particular in a range of 50% to 55%. This means that one surface of the working area preferably has a coverage density of approximately 50% broken diamonds, and the remaining surface of the working area is free of broken diamonds. This results in advantages with regard to thermal stress on the dental instrument, as sufficient gaps are present between the broken diamonds in the working area. Material removed from the ceramic crown can also be at least partially absorbed and removed in the gaps.

[0013] Synthetic diamonds are preferably uncut after the crushing process. This results in a highly irregular shape with numerous sharp edges and sharp corners.

[0014] More preferably, the binder comprises nickel, which enables the fracture diamonds to be embedded in the binder in such a way that there is no risk of fracture diamonds breaking out of the binder.

[0015] Further preferably, the working area of ​​the dental instrument has a cylindrical shape or a conical shape and further preferably the working area has a hemispherical free end or a flat end with an arcuate transition area to the remaining working area of ​​the dental instrument.

[0016] Preferably, the cylindrical working areas of the dental instrument have a diameter in the range of 1.2 mm to 1.6 mm. More preferably, conical working areas of the dental instrument have a cone angle of 3°. Such dimensions allow for particularly effective separation of ceramic crowns.

[0017] A preferred embodiment of the invention is described in detail below with reference to the accompanying drawing. It shows: Fig. 1 is a schematic side view of a dental instrument according to a preferred embodiment of the invention; Fig. 2 a schematic representation of a much enlarged surface of a working area of ​​the dental instrument of Fig. 1; and Fig. 3 a schematic, enlarged representation of the working area of ​​the dental instrument to illustrate a coating thickness with fracture diamonds.

[0018] The following is based on the Fig. 1 to 3 a dental instrument 1 according to a preferred embodiment of the invention is described in detail.

[0019] As from Fig. 1, the dental instrument 1 comprises a cylindrical shaft 2 and a working area 3. The shaft 2 serves to clamp the dental instrument into a drive, in particular with a very high speed.

[0020] Work area 3 is designed for processing ceramic crowns, particularly full ceramic crowns.

[0021] The working area 3 is set with fracture diamonds 5. The working area 3 comprises a core formed in one piece with the shaft 2. A tapered transition area 4 is provided at the transition between the shaft 2 and the working area 3 (see Fig. 1).

[0022] A binding agent 6 is applied to the working area, in which the fracture diamonds 5 are embedded.

[0023] The broken diamonds 5 are thus, as can be seen in particular from the Fig. 2 and Fig. 3, partially arranged in the binder 6 and thereby fixed. Some of the fracture diamonds protrude beyond an outer surface of the binder 6.

[0024] The fracture diamonds 5 are produced from larger diamonds using a crushing process. The crushing process breaks the larger diamonds into several pieces, resulting in a multitude of sharp edges and corners. Thus, the fracture diamonds 5 have a significantly higher number of cutting edges than uncrushed diamonds. Mechanical crushing processes are preferably used for crushing.

[0025] Synthetic diamonds are preferred for fracture diamonds because they offer significant cost advantages over natural diamonds. Synthetic diamonds can be produced relatively inexpensively in large quantities; however, they often have a predetermined geometric shape. As a result, the produced synthetic diamonds have fewer edges and corners. By using fracture diamonds, which can be produced from synthetic diamonds, the number of edges and corners can be significantly increased.

[0026] As in Fig. As shown in Figure 2, the fracture diamonds 5 have an irregular shape. The fracture diamonds 5 have a maximum length L and a maximum width B, which is measured perpendicular to the maximum length L (cf. Fig. 2). Preferably, the ratio V of maximum length to maximum width (V = L / W) is in a range from 1.00 to 2.10. Preferably, the ratio V is in a range from 1.20 to 1.80, and particularly preferably in a range from 1.40 to 1.60.

[0027] More preferably, the fracture diamonds 5 have a grain projection above a surface of the binder 6 in a range from 44 µm to 86 µm, in particular 55 µm to 75 µm, in particular 60 µm to 70 µm.

[0028] More preferably, the coverage density of the fracture diamonds in the working area is in a range of 45% to 61%, in particular in a range of 50% to 55%. This leaves sufficient space between the fracture diamonds, as in the Fig. 2 and Fig. 3, so that thermal stress on the dental instrument during the processing of hard ceramic crowns can be significantly reduced. As can be seen from the Fig. 2 and Fig.As can be seen in Figure 3, the arrangement of the broken diamonds 5 in the binding agent 6 is very irregular. Larger areas 7 that are not covered with broken diamonds can also be provided, which can also partially serve to absorb removed crown material during crown processing.

[0029] More preferably, a maximum length L of the fracture diamonds is in a range from 85 µm to 190 µm, in particular 100 µm to 170 µm, and further in particular in a range from 140 µm to 150 µm. The maximum length L of the fracture diamond is defined such that a straight line with maximum length L is measured through an embedded fracture diamond. A maximum width B of the fracture diamonds is in a range between 70 µm and 125 µm, in particular 80 µm to 120 µm, and further in particular in a range from 100 µm to 110 µm. The maximum width B is measured perpendicular to the maximum length L and is determined by a straight line perpendicular to the maximum length L.

[0030] By using fractional diamonds 5, particularly effective machining of ceramic crowns, bridges, and the like can now be achieved. The dental instrument 1 exhibits very high wear resistance. In particular, the time required to remove a crown can be significantly reduced, resulting in significantly less stress and trauma for patients. Due to the large number of cutting edges of the fractional diamonds 5, no unpleasant chattering or similar noise occurs during crown removal, making crown removal significantly more comfortable for the patient. List of reference symbols 1 dental instrument 2 shaft 3 Work area 4 tapered transition area 5 Broken diamond 6 Binders 7 diamond-free area B Width L length V ratio QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 199 08 507 A1

[0002]

Claims

[1] Dental instrument for processing ceramic crowns, comprising: - a shaft (2) for clamping the dental instrument into a drive, and - a diamond-studded work area (3) for processing the ceramic crown, - wherein a binding agent (6) is applied to the working area (3), - wherein the diamonds are partially arranged and fixed in the binding agent (6) and partially protrude beyond an outer surface of the binding agent (6), and - where the diamonds are broken diamonds (5). [2] Dental instrument according to claim 1, wherein the fracture diamonds of the working area (3) are synthetic fracture diamonds which are produced from synthetic diamonds by crushing processes. [3] Dental instrument according to one of the preceding claims, wherein the fracture diamonds have a maximum length L and a maximum width B perpendicular to the maximum length L and wherein a ratio V of the maximum length L to the maximum width B is in a range of V = L / B = 1.00 to 2.10, in particular in a range of 1.20 to 1.80, and further in particular in a range of 1.40 to 1.

60. [4] Dental instrument according to one of the preceding claims, - wherein a maximum length L of the fracture diamonds (5) is in a range from 85 µm to 190 µm, in particular in a range from 100 µm to 170 µm, and further in particular in a range from 140 µm to 150 µm, and / or - wherein a maximum width B of the fracture diamonds is in a range between 70 µm and 125 µm, in particular in a range of 80 µm to 120 µm, and further in particular in a range of 100 µm to 110 µm. [5] Dental instrument according to one of the preceding claims, wherein an embedding depth of the fracture diamonds (5) in the binding agent (6) is such that 60% to 70% of a volume of the fracture diamonds are embedded in the binding agent (6). [6] Dental instrument according to one of the preceding claims, wherein the fracture diamonds (5) have a projection above a surface of the binding agent (6) in a range of 44 µm to 86 µm, in particular 55 µm to 75 µm, further in particular 60 µm to 70 µm. [7] Dental instrument according to one of the preceding claims, wherein a coverage density of the fracture diamonds (5) on the binding agent (6) is in a range of 45% to 61% and in particular in a range of 50% to 55%. [8] Dental instrument according to one of the preceding claims, wherein the fracture diamonds (5) are unprocessed after breaking and are introduced unprocessed into the binding agent (6). [9] Dental instrument according to one of the preceding claims, wherein the binder (6) comprises nickel. [10] Dental instrument according to one of the preceding claims, wherein the working area (5) has a cylindrical shape or a conical shape.

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