DENTAL POLISHING INSTRUMENT HAVING INCREASED SERVICE LIFE

Abstract

The invention relates to a dental grinding instrument including a shaft and a grinding area arranged on the shaft, wherein the grinding area has a bonding layer and grinding elements including abrasive grains and spheres, and wherein the grinding elements are fixed to the shaft by means of the bonding layer.

Claims

1. A dental grinding instrument comprising a shaft and a grinding area disposed on the shaft, wherein the grinding area has a bonding layer and grinding elements comprising abrasive grains and spheres, and wherein the grinding elements are fixed to the shaft by means of the bonding layer.

2. The dental grinding instrument according to claim 1, wherein a proportion of the spheres in the grinding elements is in a range from 15% by volume to 45% by volume, in particular 20% by volume to 40% by volume, further particularly in a range from 25% by volume to 35% by volume and further particularly 30% by volume.

3. The dental grinding instrument according to claim 1, wherein the spheres are hollow.

4. The dental grinding instrument according to claim 3, wherein the spheres have a wall thickness in a range from 1/7 of a first diameter of the spheres to ⅕ of the first diameter of the spheres.

5. The dental grinding instrument according to claim 1, wherein the first diameter of the spheres is smaller than a second average diameter of the abrasive grains.

6. The dental grinding instrument according to claim 1, wherein the abrasive grains are diamond grains and/or DLC grains and/or carbide grains.

7. The dental grinding instrument according to claim 1, wherein the spheres are made of ceramic material.

8. The dental grinding instrument according to claim 7, wherein the spheres are made of alumina, or wherein the spheres are made of zirconium oxide, or wherein the spheres are made of a mixed ceramic material comprising alumina and zirconia.

9. The dental grinding instrument according to claim 1, wherein the bonding layer comprises nickel.

10. The dental grinding instrument according to claim 1, wherein the spheres are evenly distributed across a surface of the grinding area.

Description

[0016] A preferred embodiment of the invention will be described in detail below while making reference to the accompanying drawings, wherein:

[0017] FIG. 1 is a schematic view of a dental grinding instrument according to a preferred embodiment of the invention,

[0018] FIG. 2 is a schematic sectional view of the grinding area of the dental grinding instrument of FIG. 1,

[0019] FIG. 3 is a theoretical exploded perspective view of the grinding area of FIG. 2, and

[0020] FIG. 4 is a diagram showing a grinding time t over a number of trials n of a grinding test over a constantly equal distance in comparison with two conventional dental grinding instruments.

[0021] In the following, a dental grinding instrument 1 according to a preferred embodiment of the invention will be described in detail while making reference to FIGS. 1 to 4,

[0022] As may be seen from FIG. 1, the dental grinding instrument 1 comprises a shaft 2 and a grinding area 3. The grinding area 3 is fixed to the shaft 2.

[0023] As may be seen in detail from FIG. 2, the grinding area 3 comprises a bond layer 6 and a plurality of grinding elements. The grinding elements are partially embedded in the bonding layer 6, which is applied to the shaft 2, and thus will be fixed to the dental grinding instrument 1.

[0024] As may be seen from FIGS. 2 and 3, the grinding elements herein comprise abrasive grains 4 and spheres 5. No other grinding elements are provided. In this example embodiment, 30% by volume spheres and 70% by volume abrasive grains are provided herein.

[0025] The abrasive grains 4 are diamond grains and the spheres 5 are made of an alumina ceramic material.

[0026] As may be seen from FIG. 2, the spheres 5 are hollow. Herein, a first diameter D1 of the spheres 5 is smaller than an average second diameter D2 of the abrasive grains 4.

[0027] This results in larger interstices between adjacent abrasive grains 4 in which spheres 5 are arranged. Thus, during processing using the dental grinding instrument, a temperature at the surface of the dental grinding instrument can significantly be reduced compared to the dental grinding instruments previously used, which are solely comprised of abrasive grains. This temperature reduction enables significant extension of a service life of the dental grinding instrument according to the invention.

[0028] In FIG. 2, reference number 5′ schematically indicates a broken sphere. When machining the surface of the tooth or the like, damage to the spheres 5 may also occur. However, such damage does not affect the abrasive properties of the abrasive grains 4.

[0029] Turning now to FIG. 3, it illustrates in schematic perspective view how the grinding elements, i.e. the abrasive grains 4 and the spheres 5, are fixed to the shaft 2 by means of the bonding layer 6.

[0030] FIG. 4 shows a diagram showing a comparison between a dental grinding instrument according to the invention and two prior art dental grinding instruments. In the comparative test, the dental grinding instruments were guided over a predetermined constant test distance and were operated in rotation over a certain number of times n, in this example 10 times. For each test, a time t in seconds was determined in which the dental grinding instrument is to be guided over the predetermined constant distance so as to obtain a predetermined constant surface quality.

[0031] In FIG. 4, a first curve 101 is drawn for the dental grinding instrument 1 according to the invention. As a comparison, a second curve 102 is drawn for a dental prior art grinding instrument, which has a specific diamond coating that has specifically been developed for machining zirconium ceramics. A third curve 103 shows the behavior of a dental grinding instrument which solely comprises diamond grains as abrasive grains.

[0032] As may be seen from FIG. 4, in the first test (n=1) the service lives t are very close to each other in the range from 32 seconds (curves 101 and 102) to 35 seconds (curve 103). With an increasing number of tests performed and thus concomitant increase in temperature in the dental grinding instrument, significantly longer processing times result in each case for the second curve 102 and the third curve 103. For example, in the 10th test (n=10), the dental grinding instrument according to the invention requires approximately 52 seconds. The dental grinding instrument covered with the specific diamond coating developed for zirconia machining requires approximately 58 seconds and the dental grinding instrument covered with diamond grains requires approximately 75 seconds.

[0033] This comparison reveals that there is significant increase in service life of the dental grinding instrument 1 according to the invention compared to the prior art dental grinding instruments, which are exclusively comprised of one type of abrasive grains.

[0034] It should also be noted that the geometric shape of the grinding area 3 of the dental grinding instrument 1 of the invention can be selected as desired. In FIG. 1, a bud shape is shown. However, the inventive concept is also applicable to all other geometric shapes such as cones, cylinders, spheres, clubs, ellipses, discs, etc.

LIST OF REFERENCE NUMBERS

[0035] 1 Dental grinding instrument [0036] 2 Shaft [0037] 3 Grinding area [0038] 4 Abrasive grains [0039] 5 Sphere [0040] 5′ Sphere partially destroyed during operation [0041] 6 Bonding layer [0042] 101 First curve of a dental grinding instrument according to the invention [0043] 102 Second curve with specific prior art diamond coating [0044] 103 Third curve with diamond grains only [0045] D1 diameter of the spheres [0046] D2 Average diameter of the abrasive grains