METHOD FOR PRODUCING BLANKS FOR ENDODONTIC INSTRUMENTS

Abstract

The invention relates to a blank for an endodontic instrument, obtainable by machining at least one rod by means of wire erosion, preferably selected from the group consisting of electrical discharge machining, wire electrical discharge machining, electrical discharge grinding and electro-chemical machining, wherein an erosion pattern is applied to the at least one rod, wherein the blank has a homogenous hardness.

Claims

1. A blank for an endodontic instrument obtained by removing material from a rod by an erosion method, preferably a method selected from the group consisting of electrical discharge machining, wire electrical discharge machining, electrical discharge grinding and electro-chemical machining to form a plurality of cutting edges and flutes having a non-directional surface finish, and wherein the blank has a substantially homogenous hardness over the cross-section of the blank.

2. A method for producing blanks for endodontic instruments according to claim 1, comprising the steps of i) providing at least one rod; ii) machining the at least one rod by means of erosion, preferably selected from the group consisting of electrical discharge machining, wire electrical discharge machining, electrical discharge grinding and electro-chemical machining, wherein an erosion pattern is applied to the at least one rod, wherein material eroded away from the at least one rod at least partially deposits again as a layer on the at least one rod, and wherein the layer of the re-deposited material has a surface hardness which substantially corresponds to the hardness of the material of the at least one rod.

3. A method for producing blanks for endodontic instruments according to claim 1, comprising the steps of i) providing at least one rod; ii) machining the at least one rod by means of erosion, preferably selected from the group consisting of electrical discharge machining, wire electrical discharge machining, electrical discharge grinding and electro-chemical machining, wherein an erosion pattern is applied to the at least one rod, wherein material eroded away from the at least one rod at least partially deposits again as a layer on the at least one rod; and iii) removing substantially all of said re-deposited layer from the at least one rod.

4. The method according to claim 3, wherein the machining step is designed such that the thickness of the recast layer between the at least one rod and the re-deposited material is adjusted.

5. The method according to claim 3 or 4, wherein step iii) is performed by means of at least one of electro-polishing; chemical polishing; mechanical polishing; electrochemical polishing; magnetic abrasive polishing.

6. A method for producing blanks for endodontic instruments according to claim 1, comprising the steps of i) providing at least one rod; ii) machining the at least one rod by means of erosion, preferably selected from the group consisting of electrical discharge machining, wire electrical discharge machining, electrical discharge grinding and electro-chemical machining, wherein an erosion pattern is applied to the at least one rod, wherein material eroded away from the at least one rod does not deposit again on the at least one rod.

7. An endodontic instrument which can be produced from the blank according to claim 1, wherein the endodontic instrument has at least one of an attachment device or a holding device.

8. An endodontic instrument according to claim 7, wherein the holding device is a handle.

9. A delivery device, which is designed such that several rods can be delivered simultaneously or in succession into an erosion device for carrying out the method according to any of claims 2 to 6.

Description

[0034] The invention is explained below with reference to the FIGS. 1 and 2 and on the basis of measurement results.

[0035] FIG. 1 shows a schematic view of an endodontic instrument in the root canal of a tooth;

[0036] FIG. 2 shows a schematic view of a section of a blank.

[0037] FIG. 1 shows an endodontic instrument 1 during the treatment of a molar 11. Here, the endodontic instrument 1 is partially inserted into a root channel 12 of the tooth 11. By means of movements of rotation and translation, the root canal 12 is cleaned, i.e. the dentin removed from the root canal 12, and widened. The endodontic instrument 1 comprises a handle 3 and a body 2. The body 2 is produced from a nickel-titanium alloy and has at least one erosion pattern 4. The erosion pattern 4 was introduced in a wire erosion method. The erosion pattern 4 is formed here, inter alia, by the deposition of eroded material. The erosion pattern 4 has cutting edges, which perform a cutting function during the intended use.

[0038] FIG. 2 shows a schematic view of a section of a blank 21. The blank 21 has a surface pattern 22, which was formed in a machining process by wire erosion. The surface of the blank 21 comprises a layer of re-deposited material 23, which was formed by material eroded away from the blank 21 and deposited on the blank 21 during the machining by wire erosion (FIG. 2, ref. A).

[0039] The layer of re-deposited material 23 may be removed resulting in a blank having a surface pattern 22 and lacking a layer of re-deposited material (FIG. 2, ref. B). Alternatively, no material, which is eroded away from the blank 21, is deposited on the blank 21 during the machining by wire erosion. The latter also results in a blank as shown in FIG. 2, ref. B.

[0040] The hardness of the instruments was defined by the nanoindentation method (maximum forces 10 mN and 30 mN). The remnant depth ratio (RDR) was determined for the evaluation, likewise h.sub.max, h.sub.ver and the elastic modulus. In workpieces according to the invention, no significant difference in hardness could be identified between areas treated by EDM and areas not treated by EDM. In the endodontic application, instruments according to the invention showed excellent and homogeneous properties of bending and elasticity, without any cracking of surface material, even under intensive and prolonged stress.