Good News!An Article Co-authored by CCRC is Published in the China Medical Device Information

Congratulations to Junyue Pharmaceutical Registration and Regulation Team Li Jiyan for co-authoring the [Academic Sharing] YY/T 0803.1-2022 Standard Interpretation of “Dental Root Canal Instruments Part 1: General Requirements”, which was published in “China Medical Device Information” magazine, 2022, No. 28 Volume 11!

[Academic sharing] Interpretation of the standard of YY/T 0803.1-2022 “Dental Science Root Canal Instruments Part 1: General Requirements”

Author: Shen Lisi1 Zhou Liangbin1 Li Jiyan2 Pei Xiaohui3*

Unit: 1 Guangdong Medical Device Quality Supervision and Inspection Institute (Guangzhou, Guangdong 510663)

2 Junyue Pharmaceutical Technology (Shanghai) Co., Ltd. (Shanghai 201208)

3 China Medical Device Industry Association (Beijing 100022)


Abstract: By interpreting the latest general standard for root canal instruments, YY/T 0803.1-2022, and comparing it with YY 0803.1-2010, the main technical indicators and standard revision ideas of the standard are analyzed and summarized, so as to better understand the application of the standard. This standard provides a reference.

Key words: dentistry root canal instrument industry standard


Root canal therapy is the most commonly used and effective treatment for endodontic and periapical lesions. Root canal treatment removes the source of infection in the root canal through debridement, chemical treatment and mechanical preparation, and fills the root canal tightly to seal the crown to prevent the occurrence of periapical lesions or promote the healing of periapical lesions. For infected teeth, the first step is to use root canal instruments to remove the infection and clean the entire root canal system. Root canal instruments refer to dental instruments used for the exploration, shaping, cleaning and filling of root canals, including root canal files, root canal expanding drills, root canal presses and other products. According to various needs, modern root canal treatment instruments have been continuously developed in terms of materials and shapes to improve performance and ensure efficiency, and are widely used in clinical practice of root canal treatment.

At present, the industry standard for root canal instruments is mainly YY/T 0803 series. Among them, the first part as a general requirement is the basis for the other parts of the standard. In May 2022, the No. 39 document of the State Food and Drug Administration issued a new version of YY/T 0803.1-2022[1], which revised YY 0803.1-2010[2], in which the calculation of dimensional tolerance, tip shape, taper, Technical modifications have been made to torsion resistance, shank and rod reliability. This article intends to summarize and interpret the revision of the standard, so that the industry can grasp the content and ideas of the revision of the standard more timely and accurately, so that the standard can achieve better implementation results.

1. Brief introduction of YY/T 0803 series of standards

The YY/T 0803 series of standards specify special requirements and test methods for various fields of root canal instruments, and consist of 5 parts. Namely, Part 1: General Requirements; Part 2: Enlarging Drills; Part 3: Compressors; Part 4: Assistive Instruments; Part 5: Forming and Cleaning Instruments.
YY/T 0803.1-2022 “Dental Root Canal Instruments – Part 1: General Requirements” is the first part of YY/T 0803. This part is the basis of the YY/T 0803 series of standards. The purpose is to specify general requirements and test methods for root canal instruments used in root canal therapy (eg expanding drills, presses, auxiliary instruments, shaping and cleaning instruments), as well as a numerical coding system.
Part 2: Expand the drill. Expanding drills are used to open the crown of the root canal and enlarge the orifice of the root canal. This part of the standard mainly stipulates the specific requirements of the dental root canal expanding drill. In addition to the general requirements of Part 1, fatigue resistance is one of the main properties of the expanding drill.
Part 3: Compressor. This part specifies the requirements and test methods for vertical and lateral presses for compacting root canal filling materials. The flexural strength test of this part is different from that of Part 1, and the specific requirements are different for different devices. This part has requirements for the smoothness of the instrument head. Whether the surface of the compression head is smooth or not has a certain influence on the filling effect of the compacted root canal.
Part 4: Assistive devices. It specifies the requirements and test methods for hand-held or machine root canal instruments that are not mentioned in YY/T 0803.1, YY/T 0803.2, YY/T 0803.3, and YY/T 0803.5. Root canal aids mainly include barbed pulp extraction needles, rasps, paste conveyors, root canal probes, cotton needles, etc.
Part 5: Forming and cleaning instruments. This part applies to hand-held or electric root canal shaping and cleaning instruments used for root canal operation but not included in YY/T 0803.1~YY/T 0803.4. The types mainly include the various types of root canal files mentioned in YY/T 0803.1, and the mechanical performance indicators (torsional strength, deflection angle and stiffness) of each type of root canal file are specified. At the same time, the fracture position of the forming instrument is specified.
YY 0803.1-2010 “Dental Endodontic Instruments Part 1: General Requirements and Test Methods” has been published for more than ten years, and the international standard ISO 3630-1:2019 Dentistry-Endodontic instruments-Part 1: General requirements has been officially published, According to the national standard management method, the dental equipment and equipment sub-technical committee of the national standardization technical committee of oral materials and equipment revised the original industry standard based on the latest international standards and combined with the current situation and development trend of root canal equipment. In May 2022 On the 18th, YY/T0803.1-2022 “Dental Root Canal Instruments Part 1: General Requirements” was released. This standard is revised and adopted ISO 3630-1:2019, and the new standard will be implemented on June 1, 2023.

2. Comparison of old and new standards

YY/T 0803.1-2022 is a revised version of YY 0803.1-2010 “Dental root canal instruments – Part 1: General requirements and test methods”. Compared with YY 0803.1-2010, except for structural adjustments and editorial changes, the main technical The changes are as follows.
In terms of definition, flexible instruments and guiding instruments are deleted, and the definition of connecting rod is added.
Classification adjusted: from “Type 3: Shaped Instruments” to “Type 3: Non-Tapered Instruments” “Type 4: Non-tapered Instruments” to “Type 4: Non-Singly Tapered Instruments” “Type 5: Non-Singularized Instruments” Tapered Instruments” was changed to “Type 5: Shaped Instruments”, which was adjusted to make the entire classification clearer.
The schematic diagram of non-single taper instruments has been added to make various types of instruments more complete.
Added stem dimension schematics and tolerance list, changed shank and stem requirements. The requirements for shanks and rods are more specific.
Removed thermal effects of chemical properties, corrosion testing, and sterilization; increased repeated handling tolerance. Root canal instruments may be reusable or single-use. For reusable devices, the method of reprocessing is provided by the manufacturer, and no uniform requirements are made. There are various forms of root canal instruments on the market, and each manufacturer will have different requirements for their different products. The adjustments made here are more realistic;
Test procedure optimized: Changed taper calculation; changed “Chuck with Soft Brass Jaws” to “Chuck with Jaws” “Clockwise” to “Instrument Working Direction” in Torsion Resistance Test ;In the reliability of shank and rod, changed “clamp the operation part, leave 3mm outside” to “clamp the operation part at a position within 1mm from the shank or rod”.
Changed the reliability of the handle and stem; changed the symbol; added the identification symbol for the double cutting edge (diamond) and double helix type H-file; deleted the manufacturer’s instructions for use f); Changed to “Whether the device is single-use”.
YY/T 0803.1-2022 The above technical content changes are more suitable for the current changing needs of root canal instruments.

3. Standard interpretation

3.1 Scope of application of the standard
YY/T 0803.1-2022 “Endodontic instruments in dentistry – Part 1: General requirements” specifies the general Requirements and test methods and numerical codes. General specification marking, color coding, packaging and identification symbols are also specified. Compared with the scope in YY 0803.1-2010, this applicable scope has not changed significantly.

3.2 Interpretation of some standard clauses

3.2.1 Dimensions
tolerance. In YY/T 0803.1-2022, the projected diameter (D) tolerance of the working part tip and the diameter (d3) tolerance at 3mm of the standard instrument size 6,8,10 are changed from the original 0.01mm to 0.02mm, and the tolerance range is enlarged here , indicating that the standard is less stringent for devices with relatively small specifications. Depending on the modified tolerance, some products may have several nominal sizes depending on their dimensions, for example, a product with a projected diameter of 0.08mm at the tip of the working part and a d3 of 0.14mm may have three nominal sizes: 6, 8 and 10 . That is, the manufacturer can determine the nominal specification as appropriate considering the relevant technical indicators.
shape of the tip. Requirements in YY/T 0803.1-2022: The shape of the tip is specified by the manufacturer. The angle of the tip should be between 30˚ and 90˚. The tip length shall be specified by the manufacturer. The length range of the tip is determined by the maximum and minimum angles, in accordance with ISO 3630-1:2019. The requirement for tip angle in YY 0803.1-2010 is 60~90˚. It can be seen that the range of the tip angle in the new version is relaxed, and the minimum tip angle is changed from 60° to 30°, which means that the tip can be made more pointed. For safety reasons, a 30° tip may cause less deflection in clinical use and is more beneficial than a 60° tip. The structure of the remark tip in the standard is specified by the manufacturer, indicating that the shape of the tip of the instrument is varied and not fixed. However, the tip angle should be between 30° and 90°, and the tip length range can be calculated accordingly. The tip size is obtained by calculating the projection of the cone of the working part onto the plane of the instrument tip, which should be perpendicular to the long axis of the instrument.
Calculation of taper. YY 0803.1-2010 stipulates that the taper is calculated by measuring the diameters d2 and d3. Taper is the difference between d3 and d2 divided by the difference between l3 and l2. The error in taper is only determined by the correlation error. ISO 3630-1:2019 specifies that the taper is obtained by dividing the difference between the diameters d16 and d3 by 13. The error in taper is only determined by the relative diameter error. YY/T 0803.1-2022 In keeping with ISO 3630-1:2019, add “If the length of the working part is < 16mm, the taper is the difference between the 2nd diameter and d3 divided by the difference between the working part minus 4mm Get” an example of taper calculation when the length of the working part is < 16mm, which is more conducive to the understanding of taper calculation. The difference between l16 or working part (working part <16mm) minus 4mm and l3 are both a positioning value, which is used to determine the position of d16 or working part (working part <16mm) and d3, so there is no need to measure this dimension, that is to say If the taper calculation is divided by a fixed value, the taper error is only determined by the relative diameter error, not affected by the relative length error.

3.2.2 Torsion resistance and deflection angle
As an extremely important technical index, the torsional strength of root canal instruments is one of the keys to the success of root canal therapy. Root canal instruments with good torsion resistance can buffer excessive external torque and greatly reduce the rate of needle breakage. It is especially suitable for those clinically difficult root canals such as curvature and stenosis. The torsional performance of the endodontic instrument is achieved by testing the maximum torque and deflection angle of the endodontic instrument. In the test, YY0803.1-2010 stipulates that the jaw chuck used to clamp the specimen at a distance of 3.0mm from the tip of the root canal instrument is a chuck with soft brass clamps, while YY/T 0803.1-2022 stipulates that Chucks with metal jaws in accordance with ISO 3630-1:2019. The main reason is that the hardness of brass is lower than that of stainless steel, and the cutting performance of endodontic instruments made of NiTi alloy is very high, therefore, the forceps chuck made of soft brass cannot withstand repeated use.
YY 0803.1-2010 test procedure stipulates that “after confirming that the rotation direction of the gear motor is clockwise when viewed from the end of the specimen handle, start the gear motor to start the test loading.” YY/T 0803.1-2022 stipulates that “in the After confirming that the rotation direction of the gear motor is the working direction of the instrument as viewed from the end of the specimen handle, start the gear motor to start the test loading.” The main reason is that the current root canal instruments have various styles, and the working direction is both clockwise and counterclockwise. If the motor rotates in the opposite direction to the working direction of the root canal file, the untwisting phenomenon will occur, which is inconsistent with the actual use. Therefore, the rotation direction of the gear motor is the working direction of the instrument. This test is more comprehensive and accurate.

3.2.3 Bending resistance
Bending resistance is very important for root canal instruments. Root canal therapy is the basic treatment method for endodontic and periapical diseases, in which good root canal preparation is the basis for successful treatment. The preparation of the curved root canal is a clinical difficulty. It is necessary to prepare the root canal shape that meets the requirements, and to avoid and reduce the occurrence of root canal preparation instruments. Therefore, good bending performance is particularly important in clinical applications, the bending strength should not be too large, the root canal instruments with good elasticity are easier to enter the curved root canal, no root pressure is required, the clinical operation is easier, the comfort is higher, and the Guarantee better quality of treatment.

3.2.4 Reliability of shanks and rods
At present, the working part of most root canal files on the market is not an integral structure with the stem or handle, but is nested, so it is very necessary to examine the reliability of the handle and stem. The reliability of the stem and rod in root canal instruments is also an important guarantee for safe clinical use. The requirements in YY/T 0803.1-2022, compared with YY 0803.1-2010, have corresponding changes in performance requirements and test steps: the position of the clamping operation part in the axial movement is changed from the original 3mm outside to 1mm from the handle or rod within; increased duration of axially applied force. This test is more appropriate, more specific, and more operational. The material of the handle or rod is classified in the torsional performance. Different materials have different torsional performance, so the applied torque is also different. When the handle or rod is plastic, the applied torque is 35 mN·m; when the handle or rod is metal, the applied torque is 70 mN·m. Most of the plastic handles are manual files. The connection between the working part and the handle is different from that of the metal rod, and the actual torque is also different. The currently used root canal instruments are of various types and materials, and the materials of the handle and rod are also diverse, so the operation is more in line with the actual sample.

4. Summary

Compared with YY 0803.1-2010, the standard revision ideas of YY/T 0803.1-2022 are mainly reflected in two aspects: according to the development trend of industry technology and the deepening of understanding, the technical indicators (such as dimensional tolerance, tip shape, taper calculation) are further optimized. , anti-torsion performance, reliability of handle and rod, etc.), which helps to accommodate more diverse products and better meet clinical needs while ensuring the quality level of such products; In view of the doubts and disagreements, the expression of some methods has been revised, and the operability of the method has been effectively improved through the improvement and clarification of details, which is conducive to the better implementation of the standard. It is believed that with the update and implementation of this standard, it will be more helpful to ensure the safety of root canal instruments, standardize clinical use and improve the quality of clinical practice.

References omitted