Dental instrument for processing ceramic crowns

Abstract

The invention relates to a dental instrument for processing ceramic crowns, comprising a shaft area, comprising a shaft (2) for clamping the dental instrument into a drive, and a working area (3) studded with diamonds for processing the ceramic crown, wherein a bonding agent (6) is applied to the working area (3), wherein the diamonds are partially arranged and fixed in the bonding agent (6) and partially protrude over an outer surface of the bonding agent (6), and wherein 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 similar restorations have been increasingly used as dental prostheses. Unlike ceramic-veneered metal crowns, all-ceramic crowns are made entirely of ceramic, particularly zirconium oxide. A problem with all-ceramic crowns arises when they need to be removed. Because the ceramic used (ZrO2) is very hard, the dental instruments used for this purpose wear down very quickly. This is especially true when entire all-ceramic bridges need to be removed. For example, German patent DE 199 08 507 A1 discloses the use of diamond grains on the surface of a grinding head for grinding dental instruments. However, the dental instrument disclosed therein is only suitable for working with 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 processing all-ceramic crowns with excellent wear resistance, while being easy and cost-effective to manufacture.

[0004] This problem is solved by a dental instrument having the features of claim 1. The dependent claims describe preferred embodiments of the invention.

[0005] In contrast, the dental instrument according to the invention with the features of claim 1 has the advantage that it exhibits 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 also exhibits significantly better cutting performance than comparable dental instruments. Furthermore, the thermal stress on the dental instrument during the processing of ceramic full crowns can be significantly reduced, which also contributes to an extended service life of the dental instrument.

[0006] This is achieved according to the invention by the fact that the dental instrument for processing ceramic full crowns has a shaft for clamping into a drive and a working area studded with diamonds for processing the ceramic crown. The working area has, in particular, a core that is formed integrally with the shaft, and a bonding agent is applied to the core. The diamonds are partially arranged and thus fixed within the bonding agent and partially protrude from an outer surface of the bonding agent. The diamonds used here are fractured diamonds. Fractured diamonds are produced from larger diamonds by means of a fracturing process. The fractured diamonds used according to the invention are thus specifically produced by fracturing larger diamonds. The fractured diamonds have a multitude of sharp edges and corners, yet they are still lumpy diamonds.Due to the numerous sharp edges and corners that protrude above the bonding agent of the dental instrument, hard materials such as ceramics can be processed and, in particular, separated in an excellent way in order to remove a dental ceramic or a bridge for a patient as quickly and effectively as possible.

[0007] Preferably, the fractured diamonds in the working area are synthetic fractured diamonds. Synthetic fractured diamonds are produced by fracturing synthetically manufactured diamonds. Theoretically, natural diamonds could also be fractured for the invention; however, this is too expensive for dental instruments, so synthetic diamonds are preferably used to produce the fractured diamonds.

[0008] Preferably, the fractured diamonds have a maximum length L and a maximum width B perpendicular to the maximum length L, wherein the ratio V of maximum length L to maximum width B, V=L / B, is in a range of 1.00 to 2.10, particularly in a range of 1.20 to 1.80 and further particularly in a range of 1.40 to 1.60.

[0009] The maximum length L of the fractured diamonds is particularly preferably in the range of 85 µm to 190 µm, particularly in the range of 100 µm to 170 µm, and further particularly in the range of 140 µm to 150 µm. Preferably, the maximum width B of the fractured diamonds is between 70 µm and 125 µm, particularly between 80 µm and 120 µm, and further particularly between 100 and 110 µm.

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

[0011] The fracture diamonds particularly preferably have a protrusion above the surface of the binder in a range of 44 µm to 86 µm, and especially in a range of 55 µm to 75 µm, and further particularly in a range of 60 µm to 70 µm. This height of the fracture diamonds protruding above the binder ensures that separation processes can also be carried out on ceramic crowns.

[0012] A coverage density of the fracture diamonds on the binder is preferably in the range of 45% to 61%, and particularly in the range of 50% to 55%. This means that one surface of the working area preferably has a coverage density of approximately 50% with fracture diamonds, and the remaining surface of the working area is free of fracture diamonds. This offers advantages with regard to the thermal stress on the dental instrument, as sufficient spaces are available between the fracture diamonds in the working area. Furthermore, material removed from the ceramic crown can be at least partially absorbed and carried away from these spaces.

[0013] Preferably, the synthetic diamonds are left unprocessed after the fracturing process. As a result, the synthetic diamonds have a very irregular shape with a multitude of sharp edges and sharp corners.

[0014] Preferably, the binder contains nickel, which enables the fractured diamonds to be embedded in the binder in such a way that there is no risk of fractured diamonds breaking out of the binder.

[0015] The working area of ​​the dental instrument is more preferably cylindrical or conical in shape, and more preferably the working area has a hemispherical free end or a flat end with an arcuate transition to the rest of the 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, the conical working areas of the dental instrument have a cone angle of 3°. Such dimensions are particularly well suited for separating ceramic crowns.

[0017] A preferred embodiment of the invention is described in detail below with reference to the accompanying drawing. It shows: Fig. 1 a schematic side view of a dental instrument according to a preferred embodiment of the invention; Fig. 2 a schematic representation of a greatly 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 fractured diamonds.

[0018] The following refers to the Fig. 1 to 3 describe in detail a dental instrument 1 according to a preferred embodiment of the invention.

[0019] As from Fig. As can be seen in Figure 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, especially one with very high rotational speed.

[0020] Work area 3 is set up for processing ceramic crowns, especially full ceramic crowns.

[0021] The working area 3 is studded with fractured diamonds 5. The working area 3 comprises a core that is formed as a single unit with the shank 2. A tapered transition area 4 is provided at the interface between the shank 2 and the working area 3 (see figure). Fig. 1).

[0022] A binder 6 is applied to the work area, in which the fractured diamonds 5 are embedded.

[0023] The fractured 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. A portion of the fractured diamonds protrudes beyond an outer surface of the binder 6.

[0024] The fractured diamonds 5 are produced from larger diamonds using a fracturing process. This process breaks the larger diamonds into multiple pieces, resulting in fractured diamonds with a multitude of sharp edges and corners. Therefore, the fractured diamonds 5 have a significantly higher number of cutting edges than unfractured diamonds. Mechanical fracturing methods are preferably used for this process.

[0025] Synthetic diamonds are preferred for fracturing because they offer significant cost advantages over natural diamonds. Synthetic diamonds can be produced relatively inexpensively in large quantities; however, this often results in geometrically predetermined shapes. Consequently, manufactured synthetic diamonds have fewer edges and corners. By using fractured 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 fractured diamonds 5 have an irregular shape. The fractured diamonds 5 have a maximum length L and a maximum width B, which is measured perpendicular to the maximum length L (see Figure 2). Fig. 2) Preferably, the ratio V of maximum length to maximum width (V = L / W) is in the range of 1.00 to 2.10. Preferably, the ratio V is in the range of 1.20 to 1.80 and particularly preferably in the range of 1.40 to 1.60.

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

[0028] A preferred density of the fractured diamonds in the working area is between 45% and 61%, particularly between 50% and 55%. This leaves sufficient space between the fractured diamonds, as in the Fig. 2 and Fig. Figure 3 shows that thermal stresses on the dental instrument during the processing of hard ceramic crowns can be significantly reduced. As shown in the Fig. 2 and Fig.As can be seen in Figure 3, the arrangement of the fractured diamonds 5 in the binding agent 6 is very irregular. Larger areas 7, which are not covered with fractured diamonds, can also be provided, which can partially serve to accommodate removed crown material during the processing of a crown.

[0029] Preferably, the maximum length L of the fractured diamonds lies in a range of 85 µm to 190 µm, particularly 100 µm to 170 µm, and more preferably in a range of 140 µm to 150 µm. The maximum length L of the fractured diamond is defined such that a straight line with maximum length L is measured through an embedded fractured diamond. The maximum width B of the fractured diamonds lies in a range of 70 µm to 125 µm, particularly 80 µm to 120 µm, and more preferably in a range of 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] The use of fractured diamonds 5 now enables particularly effective machining of ceramic crowns, bridges, and similar restorations. The dental instrument 1 exhibits very high wear resistance. In particular, the time required to remove a crown can be significantly reduced, resulting in considerably less stress and trauma for patients. Due to the numerous cutting edges of the fractured diamonds 5, no unpleasant chattering or similar noises occur during crown removal, making the procedure significantly more comfortable for the patient. Reference symbol list 1 dental instrument 2 shaft 3 Work area 4 tapered transition zone 5 fractured diamond 6 Binders 7 diamond-free area B Width Length L V ratio QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 199 08 507 A1

[0002]

Claims

Dental instrument for processing ceramic crowns, comprising: - a shaft (2) for clamping the dental instrument into a drive, and - a working area (3) studded with diamonds for processing the ceramic crown, - wherein a bonding agent (6) is applied to the working area (3), - wherein the diamonds are partly arranged and fixed in the bonding agent (6) and partly protrude over an outer surface of the bonding agent (6), and - wherein the diamonds are fractured diamonds (5). Dental instrument according to claim 1, wherein the fractured diamonds of the working area (3) are synthetic fractured diamonds which are produced from synthetic diamonds by fracture processes. Dental instrument according to one of the preceding claims, wherein the fractured 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. Dental instrument according to one of the preceding claims,- wherein a maximum length L of the fracture diamonds (5) is in a range of 85 µm to 190 µm, in particular in a range of 100 µm to 170 µm, and further in particular in a range of 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. Dental instrument according to one of the preceding claims, wherein the embedding depth of the fractured diamonds (5) in the binder (6) is such that 60% to 70% of a volume of the fractured diamonds are embedded in the binder (6). Dental instrument according to one of the preceding claims, wherein the fractured diamonds (5) have a protrusion above a surface of the binder (6) in a range of 44 µm to 86 µm, in particular 55 µm to 75 µm, and further in particular 60 µm to 70 µm. Dental instrument according to one of the preceding claims, wherein the coverage density of the fractured diamonds (5) on the binder (6) is in a range of 45% to 61% and in particular in a range of 50% to 55%. Dental instrument according to one of the preceding claims, wherein the fractured diamonds (5) are unprocessed after fracture and are introduced unprocessed into the binder (6). Dental instrument according to one of the preceding claims, wherein the binder (6) comprises nickel. 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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