CN117137651A - Root canal file that security is better - Google Patents
Root canal file that security is better Download PDFInfo
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- CN117137651A CN117137651A CN202311192502.4A CN202311192502A CN117137651A CN 117137651 A CN117137651 A CN 117137651A CN 202311192502 A CN202311192502 A CN 202311192502A CN 117137651 A CN117137651 A CN 117137651A
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- titanium nitride
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- 210000004262 dental pulp cavity Anatomy 0.000 title claims abstract description 114
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 claims abstract description 48
- 229910001000 nickel titanium Inorganic materials 0.000 claims abstract description 38
- 239000011159 matrix material Substances 0.000 claims abstract description 33
- 229910001285 shape-memory alloy Inorganic materials 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 21
- 238000005121 nitriding Methods 0.000 claims abstract description 11
- FFRBMBIXVSCUFS-UHFFFAOYSA-N 2,4-dinitro-1-naphthol Chemical group C1=CC=C2C(O)=C([N+]([O-])=O)C=C([N+]([O-])=O)C2=C1 FFRBMBIXVSCUFS-UHFFFAOYSA-N 0.000 claims abstract description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 52
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 51
- 239000010936 titanium Substances 0.000 claims description 35
- 229910052751 metal Inorganic materials 0.000 claims description 33
- 239000002184 metal Substances 0.000 claims description 33
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 26
- 229910052786 argon Inorganic materials 0.000 claims description 26
- HZEWFHLRYVTOIW-UHFFFAOYSA-N [Ti].[Ni] Chemical compound [Ti].[Ni] HZEWFHLRYVTOIW-UHFFFAOYSA-N 0.000 claims description 25
- 239000007789 gas Substances 0.000 claims description 25
- 238000001816 cooling Methods 0.000 claims description 23
- 229910052759 nickel Inorganic materials 0.000 claims description 23
- 229910052719 titanium Inorganic materials 0.000 claims description 23
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 17
- 238000005266 casting Methods 0.000 claims description 15
- 239000011261 inert gas Substances 0.000 claims description 14
- 229910052757 nitrogen Inorganic materials 0.000 claims description 13
- 238000000227 grinding Methods 0.000 claims description 11
- 238000007670 refining Methods 0.000 claims description 11
- 238000003723 Smelting Methods 0.000 claims description 10
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 8
- 238000009825 accumulation Methods 0.000 claims description 6
- 238000010828 elution Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000000758 substrate Substances 0.000 claims description 6
- 238000003754 machining Methods 0.000 claims description 4
- 229910001453 nickel ion Inorganic materials 0.000 claims description 4
- 238000009661 fatigue test Methods 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 abstract description 8
- 230000008569 process Effects 0.000 abstract description 5
- 238000005260 corrosion Methods 0.000 abstract description 3
- 230000007797 corrosion Effects 0.000 abstract description 3
- 231100000331 toxic Toxicity 0.000 abstract description 3
- 230000002588 toxic effect Effects 0.000 abstract description 3
- 238000005516 engineering process Methods 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 38
- 238000002360 preparation method Methods 0.000 description 23
- 239000000463 material Substances 0.000 description 12
- 238000000576 coating method Methods 0.000 description 11
- 238000005728 strengthening Methods 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 10
- 238000004321 preservation Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 239000011253 protective coating Substances 0.000 description 6
- 230000007704 transition Effects 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 208000024216 Periapical disease Diseases 0.000 description 2
- 206010070834 Sensitisation Diseases 0.000 description 2
- 208000019786 dental pulp disease Diseases 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000002386 leaching Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000006386 memory function Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002103 nanocoating Substances 0.000 description 2
- 230000008313 sensitization Effects 0.000 description 2
- 208000031320 Teratogenesis Diseases 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000003064 anti-oxidating effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- KHYBPSFKEHXSLX-UHFFFAOYSA-N iminotitanium Chemical compound [Ti]=N KHYBPSFKEHXSLX-UHFFFAOYSA-N 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 210000000214 mouth Anatomy 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
- A61C5/00—Filling or capping teeth
- A61C5/40—Implements for surgical treatment of the roots or nerves of the teeth; Nerve needles; Methods or instruments for medication of the roots
- A61C5/42—Files for root canals; Handgrips or guiding means therefor
Landscapes
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Neurology (AREA)
- Neurosurgery (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Surgery (AREA)
- Oral & Maxillofacial Surgery (AREA)
- Dentistry (AREA)
- Epidemiology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Dental Tools And Instruments Or Auxiliary Dental Instruments (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Abstract
The invention discloses an root canal file with better safety. The root canal file with better safety comprises a root canal file matrix and a titanium nitride layer positioned on the surface of the root canal file matrix, wherein the titanium nitride layer is golden yellow in surface and uniformly and compactly coated on the root canal file matrix. The invention has excellent safety and practicability, and the NiTi shape memory alloy root canal file with the titanium nitride layer prepared by the heat treatment nitriding technology has excellent corrosion resistance, and can prevent Ni ions from exuding in the use process and reduce the toxic action on human bodies. In addition, the processing and heat treatment method adopted by the invention has simple process.
Description
Technical Field
The invention relates to the field of biomedical metal products, in particular to a root canal file with better safety.
Background
Dental pulp disease and periapical disease are common diseases of the oral cavity, and root canal treatment is a main treatment means for dental pulp disease and periapical disease. Where root canal preparation is one of the key factors in determining success or failure of root canal treatment, the root canal preparation effect is largely related to the proper root canal preparation instrument. However, clinical studies prove that Ni ions contained in Ni-Ti alloy of the nickel-titanium root canal preparation instrument are potential sensitization factors, and the dissolution of the Ni ions can bring toxic and side effects such as sensitization and teratogenesis to human bodies.
In view of the above, the preparation of a surface coating by applying a nickel titanium alloy root file material is an effective means of preventing the leaching of Ni ions. For example, chinese patent application CN116356257a discloses a process for a nickel-titanium alloy root canal file and a nickel-titanium alloy root canal file comprising: cleaning a nickel-titanium alloy root canal file; and forming a nano coating on the outer surface of the root canal file, wherein the nano coating is a Ni-La composite coating.
There is still a need for an endodontic file with a titanium nitride layer that has a simpler manufacturing process and higher safety and practicality.
The information in the background section is only for the purpose of illustrating the general background of the invention and is not to be construed as an admission or any form of suggestion that such information forms the prior art that is well known to those of ordinary skill in the art.
Disclosure of Invention
In order to solve at least part of the technical problems in the prior art, the invention provides an root canal file with a titanium nitride layer and application thereof. Specifically, the present invention includes the following.
According to the first aspect of the invention, a safer root canal file with a titanium nitride layer is provided, the root canal file comprises a root canal file substrate and the titanium nitride layer positioned on the surface of the root canal file substrate, wherein the titanium nitride layer is golden yellow in surface and uniformly and densely coated on the root canal file substrate.
In certain embodiments, a safer root canal file according to the present invention, wherein the root canal file with a titanium nitride layer is good and crack free under fatigue test conditions of 90 degrees fatigue 1500 times.
In certain embodiments, a safer root canal file according to the present invention, wherein the presence of the titanium nitride layer results in a root canal file having a nickel ion elution of less than 0.025 μg/L for 10 days.
In certain embodiments, a safer root canal file according to the present invention, wherein the molar ratio of titanium metal to nickel metal in the root canal file matrix is 50:50 to 55:45.
In certain embodiments, the root canal file with better safety according to the invention is obtained by forming a titanium nitride layer on the surface of a substrate by means of a vacuum isothermal nitriding technique.
In certain embodiments, a safer root canal file according to the present invention, wherein the root canal file is prepared by steps comprising:
a. smelting titanium metal and nickel metal under the condition of not being oxidized, then heating to 1200-1400 ℃ under the protection of inert gas or in a vacuum environment, respectively refining at high temperature, cooling to 600-1000 ℃ and casting to obtain nickel-titanium memory alloy, and processing to obtain wires;
b. and (3) processing the wire by using a root canal file, grinding a root canal file matrix with a required specification, maintaining the ground wire in a nitrogen-containing mixed gas environment with the gas pressure of 0.005-0.1 Mpa and the temperature of 550-600 ℃ for 0.5-5 hours, cooling, maintaining the ground wire in an argon environment with the temperature of 500-550 ℃ for 0.5-5 hours, and cooling in a furnace.
In certain embodiments, the root canal file with better safety according to the present invention further comprises a step of strengthening the nickel-titanium memory alloy or the processed root canal file, wherein the strengthening treatment refers to a step of repeatedly performing a stretching/unloading operation and a high-temperature treatment in an inert environment on the nickel-titanium memory alloy or the processed root canal file.
In certain embodiments, a safer root canal file according to the present invention, wherein the amount of deformation of the stretch is 1-6% repeated 5-20 times.
In certain embodiments, according to the root canal file with better safety, the obtained wire is ground into a root canal file matrix with required specification by a root canal file processing grinder, the root canal file matrix is kept for 0.5 to 5 hours in a nitrogen-containing mixed gas environment with the gas pressure of 0.005 to 0.1MPa and the temperature of 550 to 600 ℃, and after cooling, the root canal file is kept for 0.5 to 5 hours in an argon environment with the temperature of 500 to 550 ℃ and then furnace cooled; repeatedly stretching/unloading the root canal file, and then carrying out heat preservation treatment for 1-10 hours in an inert environment at 300-550 ℃; or repeatedly carrying out stretching deformation and unloading on the obtained silk material, and then carrying out heat preservation treatment in an inert gas environment at 300-550 ℃; grinding the treated wire by a root canal file processing grinder to obtain a root canal file matrix with required specification, maintaining the root canal file matrix for 0.5-5 hours in a nitrogen-containing mixed gas environment with the gas pressure of 0.005-0.1 MPa and the temperature of 550-600 ℃, cooling, maintaining the root canal file matrix for 0.5-5 hours in an argon environment with the temperature of 500-550 ℃, and cooling in a furnace; the file is subjected to repeated stretching/unloading operations, followed by a treatment with an incubation for 1-10 hours at 300-550 ℃ in an inert environment.
In certain embodiments, the safer root canal file according to the present invention, wherein the nitrogen-containing gas mixture comprises nitrogen and argon.
In certain embodiments, the safer root canal file according to the present invention, wherein the volume ratio of nitrogen to argon is 0.8:1 to 1:0.8.
In certain embodiments, a safer root canal file according to the present invention, wherein the cumulative amount of processing of the wire is controlled to be 17-60%.
In a second aspect of the invention, a method for preparing an endodontic file with a titanium nitride layer according to the invention is provided.
The root canal file with the titanium nitride layer has more excellent safety and practicability. The NiTi shape memory alloy root canal file with the titanium nitride layer prepared by the heat treatment nitriding technology has excellent corrosion resistance, and can prevent Ni ions from exuding in the use process and reduce the toxic action on human bodies. In addition, the processing and heat treatment method adopted by the invention has simple process, but has excellent corrosion resistance besides the original performance of the shape memory alloy, so as to achieve excellent protective capability.
Drawings
FIG. 1 is a surface view of an endodontic file obtained in example 1;
FIG. 2 is a surface view of the file of comparative example 2 showing a local oxidation of the file, a yellowish brown, deep purple or blue color, demonstrating the destruction of the original nitride layer in an environment where heat is preserved at high temperature and no argon protection is provided.
Detailed Description
Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in the present invention, it is understood that the upper and lower limits of the ranges and each intermediate value therebetween are specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
Root canal file with better safety
According to the first aspect of the invention, a root canal file with better safety is provided, which comprises a root canal file matrix and a titanium nitride layer positioned on the surface of the root canal file matrix, wherein the titanium nitride layer is golden in surface and uniformly and compactly coated on the root canal file matrix.
The titanium nitride layer of the root canal file has excellent stability. On the one hand, the surface of the glass is not easy to oxidize, so that the glass has uniform golden yellow. Whereas existing coatings or protective layers tend to appear different colors due to oxidation, for example, local or even whole surfaces appear earthy yellow, dark purple or blue, etc. On the other hand, the titanium nitride layer of the invention has excellent fatigue resistance, and no obvious cracks appear even after 1000 times of 90-degree fatigue and even 1500 times of fatigue.
In the present invention, the root canal file with the titanium nitride layer has a nickel ion elution of less than 0.025. Mu.g/L, in particular less than 0.020. Mu.g/L, for example less than 0.010. Mu.g/L, even less than 0.005. Mu.g/L, at 10 days due to the presence of the titanium nitride layer. In a further embodiment, the root canal file with the titanium nitride layer has a nickel ion elution of less than 0.4 μg/L, in particular less than 0.3 μg/L, such as less than 0.2 μg/L, even less than 0.1 μg/L, at 1 day due to the presence of the titanium nitride layer.
In the invention, the molar ratio of titanium metal to nickel metal in the root canal file matrix is 50:50-55:45, preferably 51-54:46-48.
Preparation method
The invention also provides a preparation method of the root canal file with the titanium nitride layer, which at least comprises the following steps: (1) a wire preparation step, (2) a titanium nitride layer step, and (3) an optional strengthening step. It will be appreciated by those skilled in the art that the numbers (1), (2) and (3) are for the purpose of distinguishing between different steps only and do not indicate the sequential nature of the steps. The order of the steps is not particularly limited as long as the object of the present invention can be achieved. In addition, it will be appreciated by those skilled in the art that other steps or operations may be included before or after steps (1) - (3) or between any of these steps, such as further optimizing and/or improving the methods described herein. The steps are described in detail below.
The step of preparing the wire material:
the method comprises the steps of smelting titanium metal and nickel metal under the condition of ensuring that titanium is not oxidized, heating the initial temperature to 1200-1400 ℃ under the protection of inert gas or in a vacuum environment, respectively refining at high temperature, standing, cooling to 600-1000 ℃ and casting to obtain nickel-titanium memory alloy, and processing to obtain the wire.
In the present invention, the condition of not being oxidized includes an inert atmosphere. Smelting may be performed in a crucible, for example. In the production method of the present invention, the titanium metal and the nickel metal are used as raw materials in an amount, on a molar basis, that is, the titanium metal is generally slightly higher than the nickel metal. For example, the molar ratio of titanium metal to nickel metal is 50:50 to 55:45. Within the above range, the effect of facilitating the nitriding reaction while maintaining the shape memory function is easily obtained. If the proportion of titanium metal is too high, the shape memory function is affected. On the other hand, if the proportion of nickel metal is too high, nickel is more likely to precipitate.
In the present invention, the temperature at the time of refining is generally 1200 to 1400 ℃, for example 1250 ℃, 1300 ℃, 1350 ℃, etc. This is not particularly limited. The temperature is reduced after refining to 600-1000 deg.C, such as 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, etc.
The preparation method of the titanium nitride layer comprises the following steps:
the preparation method of the titanium nitride layer comprises the steps of processing the obtained wire material through a root canal file, grinding the wire material into a root canal file matrix with required specification, keeping the wire material in a nitrogen-containing mixed gas environment with the gas pressure of 0.005-0.1 MPa and the temperature of 550-600 ℃ for 0.5-5 hours, cooling the wire material, keeping the wire material in an argon gas environment with the temperature of 500-550 ℃ for 0.5-5 hours, and then cooling the wire material in a furnace.
In the invention, the root canal file matrix is obtained by processing and/or grinding the wire. The size of the root canal file matrix is not limited and can be adjusted according to the needs. The machining may use known machining tools.
In the present invention, the nitriding step comprises subjecting the root file substrate to a vacuum isothermal nitriding treatment in a low pressure nitrogen containing gas mixture for a time sufficient to form a continuous nitrided layer on the surface, for example 0.5-5 hours, preferably 1-4 hours, such as 2 hours, 3 hours. The volume ratio of nitrogen and argon in the mixed gas is not particularly limited, and is generally 0.8:1 to 1:0.8. Within this range, the formation rate or permeation effect of titanium nitride can be advantageously controlled. If the nitrogen ratio is too high, although the permeation rate is increased, the bonding strength tends to be low, and it is also disadvantageous to obtain excellent fatigue resistance of the titanium nitride coating. On the other hand, if the proportion of nitrogen is too low, it is disadvantageous to form an effective titanium nitride coating thickness.
The present inventors have found that the titanium nitride layer obtained by the nitriding treatment is easily oxidized although the titanium nitride layer has a good integrity. The inventors have further studied and found that further addition of an argon high-temperature treatment step after nitriding treatment can effectively prevent the obtained titanium nitride from being oxidized. The anti-oxidation treatment comprises the steps of maintaining the obtained titanium nitride layer for 0.5-5 hours in a high-temperature argon environment after the titanium nitride layer is cooled, and then cooling the furnace to room temperature. The temperature of the oxidation preventing treatment is generally lower than that of the nitriding treatment, and is usually 500-550 ℃, such as 510 ℃, 520 ℃, 540 ℃ and 550 ℃.
Strengthening step
The strengthening step of the invention comprises the steps of repeatedly carrying out stretching/unloading operation on the nickel-titanium memory alloy or the root canal file after processing and carrying out high-temperature treatment under an inert environment.
In the present invention, the stretching is generally performed such that the deformation amount thereof is 1 to 6%, such as 2%, 3%, 4%, 5%, etc. Unloading is needed after stretching, namely, automatic recovery is achieved after the stretching stress is removed. The stretching and unloading is repeated a plurality of times, for example 5-20 times, such as 6 times, 8 times, 10 times, 12 times, 14 times, 16 times, 18 times, etc.
In the present invention, the heat treatment under the high temperature inert environment is further included after the repeated operation of the stretch unloading. The high temperature is 300-550deg.C, such as 350deg.C, 400deg.C, 450deg.C, 500deg.C, etc. The heat treatment time is generally 1 to 10 hours, preferably 5 hours or more, such as 6 hours, 7 hours, 8 hours, etc. Inert environments include inert gas environments such as argon, helium, and the like.
Example 1
This example illustrates a method of preparing an endodontic file having a surface protecting titanium nitride layer, comprising the steps of:
1. preparation of nickel-titanium shape memory alloy
And selecting a CaO crucible with high-temperature stability for smelting, ensuring the components of Ni and Ti to be accurate by ensuring that Ti is not oxidized to avoid the component proportion change caused by the formation of oxides of Ti, and obtaining the shape memory alloy with stable NiTi phase transition temperature. Wherein, the mol ratio of titanium metal to nickel metal is 52:48.
Under the protection of inert gas and the vacuum degree of 10 -2 In the environment of the support, the initial temperature is raised to 1200 ℃, high-temperature refining is respectively carried out for 5 minutes, and the casting is carried out after standing for 5 minutes and then the temperature is reduced to 800 ℃. After the nickel-titanium memory alloy is obtained through casting, the required wire is obtained through processing, and the processing accumulation amount is 30%.
2. Preparation of surface-protecting titanium nitride layer
And (3) grinding the nickel-titanium shape memory alloy wire obtained in the step (1) into a root canal file matrix with required specification through a root canal file processing grinder. And carrying out heat treatment on the processed root canal file matrix to obtain the root canal file with the surface protective coating. Wherein the heat treatment comprises: the temperature is kept at 550 ℃ for 1h in a nitrogen and argon mixed environment with the gas pressure of 0.05 MPa. After cooling, the coating is prepared in an argon environment with the gas pressure of 0.05MPa, the heat preservation temperature is 500 ℃, the heat preservation time is 1h, and the furnace cooling is more than 4 h.
Example 2
This example illustrates a method of preparing an endodontic file having a surface protecting titanium nitride layer, comprising the steps of:
1. preparation of nickel-titanium shape memory alloy
And selecting a CaO crucible with high-temperature stability for smelting, ensuring the components of Ni and Ti to be accurate by ensuring that Ti is not oxidized to avoid the component proportion change caused by the formation of oxides of Ti, and obtaining the shape memory alloy with stable NiTi phase transition temperature. Wherein, the mol ratio of titanium metal to nickel metal is 52:48.
Under the protection of inert gas and the vacuum degree of 10 -2 In the environment of the support, the initial temperature is raised to 1200 ℃, high-temperature refining is respectively carried out for 5 minutes, and the casting is carried out after standing for 5 minutes and then the temperature is reduced to 800 ℃. After the nickel-titanium memory alloy is obtained through casting, the required wire is obtained through processing, and the processing accumulation amount is 30%.
2. Preparation of surface-protecting titanium nitride layer
And (3) grinding the nickel-titanium shape memory alloy wire obtained in the step (1) into a root canal file matrix with required specification through a root canal file processing grinder. And carrying out heat treatment on the processed root canal file matrix to obtain the root canal file with the surface protective coating. Wherein the heat treatment comprises: the temperature is kept at 550 ℃ for 1h in a nitrogen and argon mixed environment with the gas pressure of 0.05 MPa. After cooling, the coating is prepared in an argon environment with the gas pressure of 0.05MPa, the heat preservation temperature is 500 ℃, the heat preservation time is 1h, and the furnace cooling is more than 4 h.
3. Strengthening treatment
The resulting file was deformed to 5% elongation at room temperature and then unloaded, and the procedure was repeated 10 times. Next, the mixture was subjected to heat-retaining treatment at 400℃for 8 hours in an inert gas atmosphere.
Example 3
The embodiment is a root canal file preparation method of strengthening treatment and nitriding treatment, comprising the following steps:
1. preparing nickel-titanium shape memory alloy:
and selecting a CaO crucible with high-temperature stability for smelting, ensuring the components of Ni and Ti to be accurate by ensuring that Ti is not oxidized to avoid the component proportion change caused by the formation of oxides of Ti, and obtaining the shape memory alloy with stable NiTi phase transition temperature. Wherein, the mol ratio of titanium metal to nickel metal is 52:48.
Adopts the inert gas protection and the vacuum degree of 10 -2 In the environment of the support, the initial temperature is raised to 1200 ℃, high-temperature refining is respectively carried out for 5 minutes, and the casting is carried out after standing for 5 minutes and then the temperature is reduced to 800 ℃. After the nickel-titanium memory alloy is obtained by casting, the required wire is obtained by processing, and the processing accumulation amount is 30%.
2. Strengthening treatment
The resulting wire was stretch deformed to 5% at room temperature, then unloaded, and the operation was repeated 8 times. Next, the mixture was subjected to heat-retaining treatment at 400℃for 8 hours in an inert gas atmosphere.
3. Preparation of surface-protecting titanium nitride layer
And (3) grinding the nickel-titanium shape memory alloy wire obtained in the step (2) into a root canal file matrix with required specification through a root canal file processing grinder. And carrying out heat treatment on the processed root canal file matrix to obtain the root canal file with the surface protective coating. Wherein the heat treatment comprises: the temperature is kept at 550 ℃ for 1h in a nitrogen and argon mixed environment with the gas pressure of 0.05 MPa. After cooling, the coating is prepared in an argon environment with the gas pressure of 0.05MPa, the heat preservation temperature is 500 ℃, the heat preservation time is 1h, and the furnace cooling is more than 4 h.
Comparative example 1
The comparative example is a root canal file preparation method without argon high temperature treatment and strengthening treatment, comprising the following steps:
1. preparation of nickel-titanium shape memory alloy
And selecting a CaO crucible with high-temperature stability for smelting, ensuring the components of Ni and Ti to be accurate by ensuring that Ti is not oxidized to avoid the component proportion change caused by the formation of oxides of Ti, and obtaining the shape memory alloy with stable NiTi phase transition temperature. Wherein, the mol ratio of titanium metal to nickel metal is 52:48.
Under the protection of inert gas and the vacuum degree of 10 -2 In the environment of the support, the initial temperature is raised to 1200 ℃, high-temperature refining is respectively carried out for 5 minutes, and the casting is carried out after standing for 5 minutes and then the temperature is reduced to 800 ℃. After the nickel-titanium memory alloy is obtained through casting, the required wire is obtained through processing, and the processing accumulation amount is 30%.
2. Preparation of surface-protecting titanium nitride layer
And (3) grinding the nickel-titanium shape memory alloy wire obtained in the step (1) into a root canal file matrix with required specification through a root canal file processing grinder. And carrying out heat treatment on the processed root canal file matrix to obtain the root canal file with the surface protective coating. Wherein the heat treatment comprises: the temperature is kept at 550 ℃ for 1h in a nitrogen and argon mixed environment with the gas pressure of 0.05 MPa. Cooling to obtain the coating.
Comparative example 2
The comparative example is a root canal file preparation method without argon high temperature treatment, comprising the following steps:
1. and smelting by selecting a CaO crucible with high-temperature stability, ensuring the components of Ni and Ti to be accurate by ensuring that Ti is not oxidized to avoid the component proportion change caused by the formation of oxides of Ti, and obtaining the shape memory alloy with stable NiTi phase transition temperature. Wherein, the mol ratio of titanium metal to nickel metal is 52:48.
Under the protection of inert gas and the vacuum degree of 10 -2 In the environment of the support, the initial temperature is raised to 1200 ℃, high-temperature refining is respectively carried out for 5 minutes, and the casting is carried out after standing for 5 minutes and then the temperature is reduced to 800 ℃. After the nickel-titanium memory alloy is obtained through casting, the required wire is obtained through processing, and the processing accumulation amount is 30%.
2. Preparation of surface-protecting titanium nitride layer
And (3) grinding the nickel-titanium shape memory alloy wire obtained in the step (1) into a root canal file matrix with required specification through a root canal file processing grinder. And carrying out heat treatment on the processed root canal file matrix to obtain the root canal file with the surface protective coating. Wherein the heat treatment comprises: the temperature is kept at 550 ℃ for 1h in a nitrogen and argon mixed environment with the gas pressure of 0.05 MPa. Cooling to obtain the coating.
3. Strengthening treatment
The resulting file was deformed to 5% elongation at room temperature and then unloaded, and the procedure was repeated 10 times. Next, the mixture was subjected to heat-retaining treatment at 400℃for 8 hours in an inert gas atmosphere.
Comparative example 3
The comparative example is a method for preparing an unreinforced root canal file, comprising the steps of:
1. preparation of nickel-titanium shape memory alloy
And selecting a CaO crucible with high-temperature stability for smelting, ensuring the components of Ni and Ti to be accurate by ensuring that Ti is not oxidized to avoid the component proportion change caused by the formation of oxides of Ti, and obtaining the shape memory alloy with stable NiTi phase transition temperature. Wherein, the mol ratio of titanium metal to nickel metal is 58:42.
Under the protection of inert gas and the vacuum degree of 10 -2 In the environment of the support, the initial temperature is raised to 1200 ℃, high-temperature refining is respectively carried out for 5 minutes, and the casting is carried out after standing for 5 minutes and then the temperature is reduced to 800 ℃. After the nickel-titanium memory alloy is obtained by casting, the required wire is obtained by processing, and the processing is accumulatedThe amount was 30%.
2. Preparation of surface-protecting titanium nitride layer
And (3) grinding the nickel-titanium shape memory alloy wire obtained in the step (1) into a root canal file matrix with required specification through a root canal file processing grinder. And carrying out heat treatment on the processed root canal file matrix to obtain the root canal file with the surface protective coating. Wherein the heat treatment comprises: the temperature is kept at 550 ℃ for 1h in a nitrogen and argon mixed environment with the gas pressure of 0.05 MPa. After cooling, the coating is prepared in an argon environment with the gas pressure of 0.05MPa, the heat preservation temperature is 500 ℃, the heat preservation time is 1h, and the furnace cooling is more than 4 h.
3. Strengthening treatment
The resulting file was deformed to 5% elongation at room temperature and then unloaded, and the procedure was repeated 10 times.
Test case
Each group of test pieces is soaked for different times to dissolve out Ni ions in the leaching solution. After soaking for 1 and 10 days, the Ni ion elution amount in each of the examples and comparative example groups was significantly reduced as compared with the control (nickel titanium group) without the titanium nitride layer. Among these, in each example, the Ni ion elution amount was further reduced as compared with the comparative example, and there was a statistical difference (P <0.05 in each case).
TABLE 1 test results for test pieces
Note that: the fatigue test condition was 90 degrees fatigue 1500 times.
While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Various modifications or changes may be made to the exemplary embodiments of the present disclosure without departing from the scope or spirit of the invention. The scope of the claims is to be accorded the broadest interpretation so as to encompass all modifications and equivalent structures and functions.
Claims (10)
1. The root canal file with better safety is characterized by comprising a root canal file matrix and a titanium nitride layer positioned on the surface of the root canal file matrix, wherein the titanium nitride layer is golden yellow in surface and uniformly and compactly coated on the root canal file matrix.
2. The safer root canal file according to claim 1, wherein the titanium nitride layer is good and crack free under fatigue test conditions of 90 degrees fatigue 1500 times.
3. A safer root canal file according to claim 2, wherein the presence of the titanium nitride layer results in a nickel ion elution of the root canal file of less than 0.025 μg/L at 10 days.
4. A safer root canal file according to claim 3, wherein the molar ratio of titanium metal to nickel metal in the root canal file base is 50:50 to 55:45.
5. The root canal file with better safety according to claim 4, wherein the root canal file is obtained by forming a titanium nitride layer on the surface of a substrate by vacuum isothermal nitriding technique.
6. The safer root canal file according to claim 5, which is prepared by comprising the steps of:
a. smelting titanium metal and nickel metal under the condition of not being oxidized, then heating to 1200-1400 ℃ under the protection of inert gas or vacuum environment for refining respectively, cooling to 600-1000 ℃ for casting to obtain nickel-titanium memory alloy, and processing to obtain wires;
b. and (3) processing the wire by using a root canal file, grinding a root canal file matrix with a required specification, maintaining the ground wire in a nitrogen-containing mixed gas environment with the gas pressure of 0.005-0.1 Mpa and the temperature of 550-600 ℃ for 0.5-5 hours, cooling, maintaining the ground wire in an argon environment with the temperature of 500-550 ℃ for 0.5-5 hours, and cooling in a furnace.
7. The safer file according to claim 6, wherein the nitrogen-containing gas mixture comprises nitrogen and argon.
8. The safer file according to claim 7, wherein the volume ratio of nitrogen to argon is 0.8:1 to 1:0.8.
9. A safer root canal file according to claim 8, wherein the machining accumulation of the wire machining is controlled to be 17-60%.
10. A method of preparing a safer root canal file according to any of claims 1-9.
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