FLEXIBLE ELECTRODE MADE OF A METAL BASE MATERIAL

Abstract

The invention relates to a flexible electrode (8) made of a metal base material (10) with a coating (18) made of polycrystalline doped electrically conductive diamond and an intermediate layer (20) between the base material (10) and the coating (18), wherein the base material (10) is in the form of a needle or wire, wherein at least one circumferential, circular or spiral groove (12) is formed in the base material (10) about a longitudinal axis (17) of the base material (10).

Claims

1. A flexible electrode (8) made of a metal base material (10) with a coating (18) made of polycrystalline doped electrically conductive diamond and of an intermediate layer (20) between the base material (10) and the coating (18), wherein the base material (10) is in the form of a needle, wire or strip, wherein at least one circumferential groove (12) is formed in the base material (10) about a longitudinal axis (17) of the base material (10).

2. The flexible electrode (8) according to claim 1, wherein the groove (12) with the intermediate layer (20) and with the coating (18) is deeper than the sum of the maximum thickness of the coating (18) and of the maximum thickness of the intermediate layer (20).

3. The flexible electrode (8) according to claim 1, wherein the diamond is doped with boron or phosphorus.

4. The flexible electrode (8) according to claim 1, wherein the base material (10) is made of titanium, niobium, tantalum, iron, or an alloy containing these metals or of steel.

5. The flexible electrode (8) according to claim 1, wherein the intermediate layer (20) is made of a metal carbide, a metal nitride, a metal boride or a mixed compound containing at least two of the mentioned carbides.

6. The flexible electrode (8) according to claim 4, wherein the intermediate layer (20) has a layer thickness of at most 10 μm, in particular at most 5 μm, and at of least 50 nm.

7. The flexible electrode (8) according to claim 1, wherein the coating (18) with diamond has a layer thickness of at most 3 μm, in particular less than 2 μm, and of at least 100 nm.

8. The flexible electrode (8) according to claim 1 for use in an antimicrobial treatment of a microbially infected endodontium or periodontium of a tooth or of a microbially infected periimplant tissue of a mammal or human.

9. The flexible electrode (8) according to claim 8 for use according to claim 8, wherein the electrode (8) forms a double electrode with an additional electrode (24), wherein the additional electrode (24) is also in the form of a needle, a wire or a strip, wherein the electrode (8) and the additional electrode (24) are interconnected in a region by at least one connection means (22) or by a connection means (22) and a spacer, so that thereby an electrical contact (29) between the electrode (8) and the additional electrode (24) is excluded and, over at least 80% of the length of this region between the electrode (8) and the additional electrode (24), a free space to be occupied during the treatment by an electrolyte is ensured, wherein a spacing between the electrode (8) and the additional electrode (24) within this space is between 40 μm and 300 μm.

10. The flexible electrode (8) according to claim 9, wherein, during the treatment, the electrode (8) is connected as anode and the additional electrode (24) is connected as cathode.

11. The flexible electrode (8) according to claim 9, wherein the additional electrode (24) is made of the same base material (10) as the electrode (8) and has the same structure as the electrode (8).

12. The flexible electrode (8) according to claim 11, wherein, during the treatment, the electrode (8) and the additional electrode (24) are each alternatingly connected as anode and the respective other of the two electrodes (8, 24) is connected as cathode.

13. The flexible electrode (8) according to claim 9, wherein the spacing between the electrode (8) and the additional electrode (24) within the space is between 40 μm and 200 μm, in particular between 40 μm and 110 μm.

14. The flexible electrode (8) according to claim 9, wherein the connection means (22) is an electrically insulating adhesive, in particular an epoxy resin, a plastic filament, or a nonconductive diamond, and the spacer is Teflon or a wire with an electrically insulating coating.

15. The flexible electrode (8) according to claim 8, wherein the treatment of the microbially infected endodontium after the antimicrobial treatment comprises an at least partial filling of a cavity existing in the tooth or formed by another treatment, with a plastic cured by electrical activation in the cavity or with an inorganic substance, the precipitation of which from a solution in the cavity is initiated by anodic oxidation, wherein the activation or the anodic oxidation occurs by means of the electrode in the cavity.

16. A method of treatment, comprising administering the flexible electrode (8) according to claim 1 in an antimicrobial treatment of a microbially infected endodontium or periodontium of a tooth or of a microbially infected periimplant tissue of a mammal or human.

Description

[0037] The figures show:

[0038] FIG. 1 a diagrammatic representation of an electrode according to the invention, which forms a double electrode with an additional electrode,

[0039] FIG. 2 a diagrammatic representation of a tooth and a dentistry instrument holder with an electrode according to the invention held thereby and supplied with current, as a component of a double electrode,

[0040] FIG. 3 a diagrammatic cross-sectional representation of an experimental setup for inactivating Staphylococcus epidermidis and Bacillus subtilis in a drilled root canal of a human tooth,

[0041] FIG. 4 a diagram showing the dependency of the growth of Staphylococcus epidermidis on the charge quantity and on the duration of the treatment of the root canal, and

[0042] FIG. 5 a diagram showing the dependency of the growth of Bacillus subtilis on the charge quantity and the duration of the treatment of the root canal.

[0043] In FIG. 1, a greatly enlarged diagrammatic cross section through the tip of an electrode 8 according to the invention in the form of a needle is shown. The electrode consists, inter alia, of the base material 10 which comprises grooves 12. During the coating with the coating 18 made of doped diamond, the intermediate layer 20 is formed directly on the base material 10. As an example, 14 marks a highest point directly surrounding the coated groove and 16 marks a deepest point of the coated groove. For the measurement of the depth of the coated groove, auxiliary lines 15 can be drawn through the highest point 14 directly surrounding the coated groove and the deepest point 16, parallel to the longitudinal axis 17 of the electrode 8. The spacing between these two lines represents the depth of the groove 12. The highest point 14 directly surrounding the coated groove 12 can also lie in a region, not represented here, extending parallel to the longitudinal axis 17. In this case, a plurality of highest points 14 directly surrounding the coated groove 12 and located at the same height then exists. The sum of the maximum thickness of the coating 18 and of the intermediate layer 20 is smaller than the depth of the coated groove 12. The electrode 8 is connected by a connection means 22, for example, by an adhesive or by a nonconductive diamond, to an additional electrode 24. Both the additional electrode 24 and the electrode 8 are flexible. Because the connection means 22 interconnects the two electrodes 8, 24 only at a few points, the flexibility of the double electrode formed by the electrode 8 and the additional electrode 24 is ensured by the connection. The additional electrode 24 can be made of steel, for example. The double arrow represented below the electrode 8 symbolizes the flexibility of the electrode.

[0044] FIG. 2 diagrammatically shows a handle 26 of a dentistry instrument which provides a current connection to a base 28. The base 28 has electrical contacts 29 on which the electrode 8 and the additional electrode 24 have been secured by soldering via the soldering sites 30. In the present case, both the electrode 8 and the additional electrode 24 are designed as electrodes according to the invention with a coating 18 with electrically conductive boron-doped diamond. The electrode 8 is here connected as anode. The additional electrode 24 connected as cathode is wrapped with a Teflon-coated polyethylene filament 32 made of polyethylene having an ultra high molecular weight. The Teflon coating here reduces the friction on the diamond coating and thus the mechanical stressing thereof. The wrapping is used here as spacer. A portion of the polyethylene filament 32 also is wrapped around the electrode 8 and used for the immobilization when the connection means 22 is attached. The connection means 22 can be a cyanoacrylate adhesive, for example. The double electrode thus formed by the electrode 8 and the additional electrode 24 is introduced into the root canal 38 of a tooth which is represented diagrammatically here. It can be energized here and, in the process, it releases OH radicals and other microbially active species.

[0045] Preparation of an agar growth medium

[0046] Liquid Standard 1 nutrient growth medium (St. 1) with agar-agar is referred to below as St. 1 agar. The components of this St. 1 agar are listed in the following Table 1.

TABLE-US-00001 TABLE 1 Ingredients of Standard 1 agar nutrient growth medium in 400 mL demineralized water Ingredients Quantity [g] Manufacturer/article number Glucose 0.44 Carl Roth GmbH/6780.1 monohydrate Sodium chloride 2.34 Carl Roth GmbH/3957.1 Agar-agar 8.00 Carl Roth GmbH/5210.3 Yeast extract 1.20 Carl Roth GmbH/2363.3 Peptone from casein 6.00 Merck KGaA/1.02239.0500

[0047] The pH was adjusted to 7.4 by addition of sodium hydroxide. The St. 1 agar plated in petri dishes solidified after a few minutes and was used as growth medium.

[0048] Inactivation of Staphylococcus epidermidis and Bacillus subtilis in a drilled root canal of a human tooth

[0049] Extracted human teeth with drilled root canal were obtained from a dentist. The teeth were first incubated for at least 20 hours in a physiological saline solution containing Staphylococcus epidermidis or Bacillus subtilis. Here, the root canals were colonized with the respective bacteria. Subsequently, the teeth were rinsed with physiological saline solution and arranged in physiological saline solution as electrolyte, in the experimental setup shown in FIG. 3. The anode designed as electrode according to the invention here consisted of a niobium wire coated with boron-doped diamond and the cathode consisted of steel. A voltage in the range from 5 to 9 volt was applied, so that the current intensities indicated in FIGS. 4 and 5 flowed in the respective indicated treatment time.

[0050] After the respective indicated treatment time, the respective tooth was split, and the resulting inner split surfaces comprising the surface of the root canal were pressed repeatedly onto an St. 1 agar growth medium and then placed with this surface on the agar. The agar growth medium was then incubated at 27 degrees for 1-2 days. Bacterial growth could be detected by the formation of colonies. The colonies were detectable as dots with the naked eye and they were classified subjectively as no growth, moderate growth, medium growth and strong bacterial growth.

[0051] Inactivation of Staphylococcus epidermidis

[0052] The results which can be seen in FIG. 4 show that already at a current quantity of 4 As, corresponding to a treatment time of 3.5 minutes, a complete sterilization of the inner root canal surface was achieved. Bacterial growth was found on none of the agar growth media.

[0053] Inactivation of the Bacillus subtilis

[0054] The results which can be seen in FIG. 5 show that with a current quantity of 5 As, corresponding to a treatment time of 8.5 minutes, a complete sterilization of the inner root canal surface was already observed. A moderate bacterial growth appearing after a treatment time of 42 minutes and a current quantity of 25 As may have been caused by the ability of the Bacillus subtilis to form spores and the possible presence of these spores in the small dentin canals of the tooth root. Furthermore, it was observed that, in the case of spore formation, the charge quantity necessary for complete sterilization can be more than one hundred times higher.

[0055] The tests carried out on the extracted tooth show that an electrode according to the invention, coated with boron-doped diamond and connected as anode, is well suited for disinfecting a root canal in a relatively short time. Such an anode can be introduced for this purpose during a tooth treatment into an opened root canal and energized. The cathode necessary for this purpose can be arranged in the vicinity of the tooth to be treated within the oral cavity. Alternatively, the electrode according to the invention can be designed as part of a double electrode which, as such, can be introduced into the root canal, as diagrammatically shown in FIG. 2.

LIST OF REFERENCE NUMERALS

[0056] 8 Electrode [0057] 10 Base material [0058] 12 Groove [0059] 14 Highest point directly surrounding the coated groove [0060] 15 Auxiliary line [0061] 16 Deepest point [0062] 17 Longitudinal axis [0063] 18 Coating [0064] 20 Intermediate layer [0065] 22 Connection means [0066] 24 Additional electrode [0067] 26 Handle [0068] 28 Base [0069] 29 Electrical contact [0070] 30 Soldering site [0071] 32 Polyethylene filament [0072] 34 Dental enamel [0073] 36 Dentin [0074] 38 Root canal