Endodontic file set
The endodontic file set harmonizes the bending and torsional stiffness of tools through material and geometric adjustments, simplifying treatment and reducing breakage risk.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- BRAND GMBH & CO KG
- Filing Date
- 2025-11-05
- Publication Date
- 2026-05-21
Smart Images
Figure DE2025101026_21052026_PF_FP_ABST
Abstract
Description
[0001]
[0002] Applicant Brand KG
[0003] Völlinghauser Straße 44
[0004] 59609 Anröchte
[0005] Our reference BRK2403PCT
[0006] Date: November 5, 2025
[0007] Endodontic file set
[0008] The invention relates to an endodontic file set for root canal preparation. The file set comprises at least two files, each with a longitudinally extending tool and a shank designed to receive the tool and to be inserted into a receptacle of a dental handpiece. The files in the file set differ, among other things, in their tool diameter, in order to achieve the desired final preparation size using a sequence of different files, depending on the technique (for example, crown down, step back, single length). For example, in the single length technique, the root canal preparation begins with a file with a small tool diameter. In subsequent treatment steps, the tool diameter of the files increases. During root canal treatment, the dental handpiece rotates or oscillates the files, which are inserted shank-first into the receptacle of the handpiece.It uses a drive system for this purpose, for example an electric motor or a pneumatic drive.
[0009] The DIN EN ISO 3630 series of standards standardizes endodontic files used in practice with regard to various geometric and functional parameters. Among other things, the standard defines a maximum flexural stiffness and a minimum torsional stiffness for different classes of tools, depending on a characteristic diameter, the so-called design diameter. The standard specifications are designed so that the tools, regardless of their design diameter, always exhibit sufficient flexibility while maintaining adequate torsional stiffness. This ensures sufficient protection against damage to the tools, particularly breakage during treatment, while simultaneously providing good handling and clinical performance.
[0010] Since the files in a set used by dentists to prepare a root canal differ in their diameter and various other parameters, they exhibit significantly different flexural and torsional stiffness. The properties and handling of each individual file are therefore different and unique, requiring the dentist to constantly adapt to each new file used during treatment.
[0011] The object of the present invention is to provide an improved endodontic file set.
[0012] To solve this problem, the invention has the features of claim 1. Accordingly, the endodontic file set comprises at least two files, each with a tool extending in a longitudinal direction and each with a shank that receives the tool and is formed for inserting the file into a receptacle of a dental instrument. All tools of the file set have a conical working part with at least one typically spirally or oval-shaped wound cutting edge and a different working diameter, the working diameter of each tool being in the range of 0.06 to 0.564 mm.According to the invention, the magnitude of the difference in actual bending stiffness and / or the magnitude of the difference in actual torsional strength between at least two tools of the file set is less than the magnitude of the difference in maximum bending stiffness and / or minimum torsional strength for these tools, as determined from the standard specifications. To adjust the actual bending stiffness and / or the actual torsional strength of each tool, its material, its heat treatment during manufacturing, and / or its cross-section with respect to a cross-sectional shape and / or cross-sectional area are adapted such that the tools of the file set differ with respect to at least two of these three adjustable parameters.
[0013] The particular advantage of the invention lies in the fact that by reducing the difference in the actual bending stiffness and torsional stiffness of the tools in the file set, dental treatment can be improved or simplified. The properties of the various tools in the file set are harmonized. They thus differ less significantly in terms of their bending properties and torsional behavior. The dentist therefore needs to make fewer adjustments when changing files during treatment.
[0014] In particular, the difference in actual bending stiffness is reduced by making tools with a large cutting diameter more flexible. Besides equalizing the properties of the different files, this has the positive effect of making the more flexible tools easier to guide through curved root canals and maintain their original canal shape. To reduce the difference in actual torsional stiffness, the actual torsional stiffness of tools with a small cutting diameter is increased. This not only reduces the difference in actual torsional stiffness but also lowers the risk of torsional fracture in these particularly fragile, small tools.
[0015] The nominal diameter of each tool is determined according to the standard at a distance of 3 mm from the tool tip. The actual bending stiffness and the actual torsional stiffness of the various tools in the file set are then determined for the nominal diameter, i.e., at a distance of 3 mm from the tool tip. The determined values for the actual bending stiffness and the actual torsional stiffness must comply with the specifications of the standard for each tool in the file set. If this is ensured, each tool can be individually adjusted with respect to its actual bending stiffness and its actual torsional stiffness. According to the invention, the file set comprises at least two conical tools with a nominal diameter in the range of 0 to 0.564 mm. According to the standard, the conical tools are found in classes 1, 2, 4, and 5.Within the classes, the standard further distinguishes three types of tools: FL files, K files, and K drills, for which different standard specifications regarding maximum flexural stiffness and minimum torsional stiffness are prescribed. The invention does not make use of this distinction between conical tools according to class and / or type. It utilizes, regardless of type, the most critical standard specifications, namely the highest value for minimum torsional stiffness and the lowest value for maximum flexural stiffness, that the standard specifies for any class and / or any of the three types mentioned.
[0016] In addition to at least two conical tools of any type, the file set may include further files. These additional files may also have diameters within the aforementioned range. Furthermore, files with a diameter larger than 0.564 mm may be included in the file set.
[0017] The various files or tools in a file set are typically used sequentially during root canal treatment, starting with the tool with the smallest working diameter, to prepare the root canal. The length of the tool, and in particular the length of the working portion (which has at least one cutting edge), is tailored to the type of tooth on the one hand and the individual patient's physical characteristics on the other.
[0018] To selectively influence the actual bending stiffness and torsional strength of the various tools in the file set, the invention always utilizes at least two of three adjustable parameters. Firstly, the material for each tool can be individually selected according to requirements. Secondly, each tool can undergo an individual heat treatment during manufacturing, adapted to its geometry and / or material. Finally, the actual bending stiffness and torsional strength can be adjusted via the cross-sectional shape and area itself.According to a preferred embodiment of the invention, the differences in actual bending stiffness and / or torsional stiffness between all tools in the file set are smaller than the differences in maximum bending stiffness and / or minimum torsional stiffness between the tools as determined by standards. This advantageously results in a further harmonization of the properties of all tools in the file set, thereby simplifying and improving tool handling and root canal preparation. Furthermore, the harmonization of the actual bending stiffness and torsional stiffness of all tools reduces the risk of damage from tool breakage due to bending or torsion occurring during treatment.
[0019] According to a further development of the invention, the difference in actual torsional stiffness between two, and preferably between any, tools of the file set, based on the defined diameter of these tools, is a maximum of 30 mN m per mm, preferably less than 20 mN m per mm, and particularly preferably less than 10 mN m per mm, and / or the difference in actual bending stiffness between two, and preferably between any, tools of the file set, based on the defined diameter of these tools, is 40 mN m per mm, preferably less than 20 mN m per mm, more preferably less than 10 mN m per mm, and particularly preferably less than 5 mN m per mm. The tools of the file set therefore exhibit an actual torsional stiffness and / or an actual bending stiffness that changes only to a comparatively small extent with respect to the defined diameter. Advantageously, this results in the tools of the file set having similar properties.Changing tools during root canal treatment is then easily accomplished without the need for extensive retraining to the new tool with its typically larger diameter, typically lower flexibility or higher flexural rigidity, and typically higher torsional strength.
[0020] According to a further development of the invention, each tool in the file set meets the standard specifications with regard to maximum flexural stiffness and minimum torsional strength. This advantageously further reduces the risk of damage. According to a further development of the invention, the at least two tools in the endodontic file set differ with respect to all three adjustment parameters.
[0021] Advantageously, the variation of the three setting parameters allows the amount of the difference to be further reduced and the actual bending stiffness or the actual torsional strength of the different tools in the file set to be even more similar to each other.
[0022] According to a further development of the invention, at least one tool of the file set is made from a NiTi-based alloy. Zirconium, chromium, hafnium, gold, manganese, vanadium, iron, cobalt, or copper are preferably provided as further alloying elements of the NiTi-based alloy. For example, the NiTi-based alloy is designed as a ternary or quaternary NiTi-based alloy. The tool is particularly preferably made from a NiTiCr, NiTiCu, or NiTiCuCr alloy. Advantageously, by using NiTi-based alloys for the at least one tool, its actual bending stiffness and its actual torsional strength can be adapted to requirements within wide limits through an appropriate selection of the alloying elements and its heat treatment.This allows the actual bending stiffness of tools with a large cutting diameter to be reduced and the actual torsional stiffness of tools with a small cutting diameter to be increased. Consequently, this further reduces the difference in the actual bending stiffness and torsional stiffness of the tools in the file set. At the same time, it is possible to comply with the standard specifications regarding maximum bending stiffness and minimum torsional stiffness.
[0023] According to a further development of the invention, at least two tools of the file set are made of NiTi-based alloys that exhibit different microstructures at a tooth root temperature of typically 35 ± 3°C and at a room temperature of typically 21 ± 5°C, respectively. The microstructure can be fully martensitic, partially martensitic and partially austenitic, or fully austenitic. The respective microstructure is defined by the phase transition temperature, with the parameters "Austenite Finish" for the fully austenitic microstructure and "Martensite Finish" for the fully martensitic microstructure. The alloy is then selected and the phase transition temperature is adjusted relative to the room or tooth root temperature such that it tends to decrease with increasing file diameter. In this way, it is possible to influence and adjust the actual bending stiffness and / or torsional strength of the tools as required.
[0024] For example, a file set with three tools made of different NiTi alloys can be configured so that the tools exhibit the following microstructures at tooth root temperature: The tool with the smallest working diameter has a fully austenitic microstructure. The austenitic finish temperature of this tool is lower than that of the other tools and, in particular, lower than the tooth root temperature. The microstructure of the tool with the medium working diameter is partially martensitic and partially austenitic. It has a martensitic finish temperature that is lower than the tooth root temperature and an austenitic finish temperature that is higher than the tooth root temperature. Finally, the tool with the largest working diameter has a fully martensitic microstructure and a martensitic finish temperature that is higher than the tooth root temperature.
[0025] According to a further development of the invention, at least one tool of the file set is made of a high-strength steel. High-strength steels are particularly suitable for small tools, i.e., tools with a small cutting diameter. Due to the material, they are characterized by advantageously high torsional strength.
[0026] According to a further development of the invention, at least one tool of the file set is subjected to heat treatment during manufacturing, such that it is tempered for a period of 5 to 240 minutes in a temperature range of 250 to 550 °C. Advantageously, the duration of the heat conversion is 5 to 30 minutes and the temperature of the heat treatment is 400 to 500 °C. Tempering improves the strength and toughness of the tools. At the same time, brittleness is reduced. The Krista II structure of the tool is influenced by nickel-rich precipitates formed during tempering. In particular, a ductile structure is formed with advantageous properties with regard to deformability under bending and torsional stress.
[0027] The geometric design of the tool, particularly in the working area, has a significant influence on its torsional and bending properties, as the corresponding torsional and bending resistance moduli increase exponentially with diameter. These resistance moduli can be further adjusted and varied by modifying the cross-sectional shape and area. Simultaneously, the cutting performance and chip space can be influenced by the number of cutting edges, their cross-sectional shape, and their area.
[0028] According to a further development of the invention, the file set provides tools with a varying number of cutting edges. For example, tools with a small cutting diameter can have a greater number of cutting edges than tools with a larger cutting diameter. Due to the large number of cutting edges, the cross-sectional area is typically larger than with a small number of cutting edges. This means that tools with a large cutting diameter can be made more flexible by reducing the number of cutting edges, and / or that tools with a small cutting diameter can be made stiffer by increasing the number of cutting edges.
[0029] According to a further development of the invention, at least one tool of the endodontic file system has a working part with a cross-sectional shape that changes in the longitudinal direction. The shape of the leading edges between the cutting edges changes with increasing distance from a tip of the tool, preferably from convex to concave. Advantageously, the bending stiffness and torsional stiffness can be directly influenced by changing the cross-sectional shape. The cross-sectional area is typically larger for a convex leading edge than for a concave leading edge. This means that by appropriately adjusting the cross-sectional shape, the torsional stiffness and / or the bending stiffness of a tool can be adjusted in its longitudinal direction.
[0030] The various tools of the endodontic file set can be inserted into the holder of the dental handpiece or dental instrument via their shanks and set in rotation or oscillation by means of a torque-limited drive. Providing torque limitation prevents tool breakage during root canal treatment. Increasing the torsional strength of the tools with the small diameters allows for an overall increase in permissible torques. A further development of the invention provides that not every tool in the file set has an individual torque cut-off value that must be set and observed on the drive side. Instead, the file set has at least one fewer torque cut-off value than the number of individual tools. At least two tools thus share one torque cut-off value.
[0031] It is particularly advantageous to have only a single torque cut-off value for the entire file set, meaning that all tools in the set have the same torque cut-off value. Consequently, less adjustment or fine-tuning of the permissible torque is required during treatment.
[0032] Further advantages, features, and details of the endodontic file set according to the invention can be found in the dependent claims, the drawings, and the following description. Features mentioned therein can be essential to the invention individually or in any combination. Thus, the disclosure relating to the individual aspects of the invention can always be referenced reciprocally. The drawings serve only as examples to clarify the invention and are not intended to be limiting.
[0033] They show:
[0034] Fig. 1 shows a perspective longitudinal side view of an endodontic file with a tool and a shank.
[0035] Fig. 2 shows a longitudinal section through the endodontic file according to Fig. 1,
[0036] Fig. 3 shows a first cross-sectional shape of a tool, an endodontic file,
[0037] Fig. 4 shows a second cross-sectional shape of an endodontic tool.
[0038] File, Fig. 5a to 5d a first embodiment of an endodontic file set with two files, wherein longitudinal side views of the two endodontic files as well as two cross-sections AA and BB through two different tools of the files are shown,
[0039] Fig. 6 shows a compilation of different cross-sectional shapes of endodontic tools.
[0040] Fig. 7 shows a tabular overview of normalized values of the minimum torsional strength of different endodontic tools and the amount of their difference.
[0041] Fig. 8 shows a tabular overview of normalized values of the maximum flexural stiffness of different endodontic tools and the amount of their difference.
[0042] Figs. 9a to 9j show a second embodiment of the endodontic file set with five files, wherein longitudinal side views of the five endodontic files and five cross-sections AA and BB through five different tools of the files are shown.
[0043] An endodontic file 1.1 according to Figures 1 and 2 is used in dentistry to treat the root canal of a diseased tooth and, as part of this treatment, to remove, for example, pulp and / or dentin with the aim of preserving the tooth. The file 1.1, which the dentist uses for root canal preparation, comprises a longitudinally extending tool 10.1 and a shank 2.1 that receives the tool 10.1 and is designed to be inserted into a receptacle of a dental instrument (not shown). The tool 10.1, in turn, has a working part 15 and a transition part 13. The transition part 13 is arranged between the shank 2.1 and the working part 15. Together with the working part 15, the transition part 13 defines a length 11 of the tool 10.1.
[0044] The working part 15 of the tool 1 has a taper 20. It tapers towards a tip 16 opposite the shank 2.1. In the present embodiment, the conical tool 10.1 has a working part with two spirally wound cutting edges 21, which are evenly distributed in a circumferential direction 22 of the tool 10.1.
[0045] The cutting edges 21 are arranged at an angle α relative to the longitudinal direction 12. Furthermore, the cutting edges 21 have a cutting distance P defined in the longitudinal direction 12.
[0046] The taper 20 of the tool 10.1 is designed such that a tip diameter do of the tool 10.1 is defined at the tip 16 and the tool 10.1 then widens towards the transition part 13. At a measuring distance l3 of 3 mm from the tip 16, the tool 10.1 has a measuring diameter d3.
[0047] For the defined diameter d3, standard values for flexural stiffness and torsional stiffness are determined according to the relevant standard series DIN EN ISO 3630 (here: Part 5 of the standard, dated December 2020). The standard defines standard values for the maximum flexural stiffness and the minimum torsional stiffness of various tools. The standard distinguishes between different classes of tools and, within each class, different types of tools. Within the scope of the invention, tools of classes 1, 2, 4, and 5 are considered. Different types of these tools are not further distinguished. Instead, the invention utilizes, across classes and types, the most critical standard values, namely the highest value for minimum torsional stiffness and the lowest value for maximum flexural stiffness, which the standard specifies for any conical tools of classes 1, 2, 4, and 5, regardless of type.These relevant standard values for the maximum bending stiffness and the minimum torsional strength of the tools are given in Figs. 7 and 8 in the second column of the tables as a function of the determining diameter d3 (column 1 of the tables).
[0048] The transition piece 13 of the tool 10.1 serves as a length compensator between the shank 2.1 and the working part 15 of the tool 10.1. For a given length 11 of the tool 10.1, the length of the transition piece 13 is directly determined by the length of the working part 15. The length of the transition piece 13 is indicated by ring markings 14. These ring markings 14 allow the dentist to determine the length of the working part 15 of the file 1.1.
[0049] The shank 2.1 of the file 1.1 has a receiving contour 6 at one end opposite the tip 16 of the tool 10.1. This contour has a contact surface 7 and an annular segment groove 8, which serves to positively lock the shank 2.1 in the dental instrument and to transmit a rotary movement from the dental instrument, for example, an electrically or pneumatically driven handpiece, to the file 1.1. Additionally, the shank 2.1 has a taper marking 3 formed by annular grooves, which indicates the taper 20 of the working part 15 of the tool 10.1. Furthermore, an annular color marking 4 is provided, which indicates the tip diameter d0 of the tool 10.1 at the tip 16.
[0050] Furthermore, a stopper 5 is provided between the shank 2.1 and the working part 15 of the tool 10.1, which is slid onto the transition part 13. The stopper 5 is movable in the longitudinal direction 12. It defines a maximum penetration depth of the tool 10.1 into the root canal and prevents the rotating shank 2.1 from coming into contact with the tooth during treatment.
[0051] Figures 3 and 4 show different cross-sectional variants of the tool 10.1 at the cutting distance l3 of the working part 15. The cross-sections differ in two aspects that influence the actual bending stiffness and the actual torsional stiffness of the tool 10.1: the cross-sectional area and the cross-sectional shape, which is determined by the number of cutting edges 21 and the contour edges that define the cross-sectional shape between the cutting edges 21. The cutting diameter d3 of both variants is the same.
[0052] Figure 3 shows an example of a centric and symmetrical S-shaped cross-section with two opposing cutting edges 21, with respect to a center point 17 of the tool 10.1, and Figure 4 shows an eccentric S-shaped cross-section. In each case, the cutting edges 21 define the same diameter of rotation 19, which extends through the center point 17 of the tool 10.1. The cutting edge envelope 18 of the symmetrical tool 10.1 according to Figure 3 is congruent with the diameter of rotation 19. In contrast, the cutting edge envelope 18 of the eccentric cross-sectional shape according to Figure 4 is smaller than the diameter of rotation 19. The diameter of rotation 19 defines the determining diameter d3 in the region of the determining distance l3. Despite the essentially identical cross-sectional shape, the cross-sectional area of the cross-section according to Figure 4 is smaller than that of the cross-section according to Figure 3.The cause of this is the eccentricity and the resulting reduction in the diameter of the cutting edge envelope 18.
[0053] Figures 5a to 5d show a first file set according to the invention with two files 1.2, 1.3. The two files 1.2, 1.3 each provide a tool 10.2, 10.3 of the same length 11 as well as a shank 2.2, 2.3 and a stopper 5.
[0054] The cross-sectional shape of a first tool 10.2 is convex and triangular. The working part 15 of the first tool 10.2 thus has three cutting edges 21. It is symmetrical with respect to the center point 17. A second tool 10.3 of the second file 1.3 is S-shaped and therefore has two cutting edges. The cross-sectional shape is eccentric, with the result that the cutting edge envelope 18 and the rotation diameter 19 do not coincide.
[0055] The different cross-sectional shapes of the first tool 10.2 and the second tool 10.3 serve to approximate their actual bending stiffness and actual torsional stiffness. For this purpose, the actual torsional stiffness of the first tool 10.2, with its smaller cutting diameter d3, is increased compared to the standard value by choosing a comparatively large cross-sectional area for this first tool 10.2 compared to the area enclosed by the rotation diameter 19. Conversely, the cross-sectional area of the second tool 10.3 at the cutting point is comparatively small relative to the area enclosed by the rotation diameter 19. This small cross-sectional area ensures that, while still providing sufficient actual torsional stiffness that meets the standard value, the actual bending stiffness is reduced.
[0056] The cross-sectional shapes of the working part 15 of the first tool 10.2 and the working part 15 of the second tool 10.3 are shown only as examples. Fig. 6 shows further variations with respect to the cross-sectional shape. These variations differ, firstly, in the number of cutting edges 21. Cross-sectional shapes with four cutting edges 21, three cutting edges 21, and two cutting edges 21 exist. A high number of cutting edges 21 tends to increase the actual bending strength and the actual torsional strength, since the cross-sectional area is comparatively large relative to the area of the rotational diameter 19. Conversely, the actual bending stiffness and the actual torsional strength decrease with a low number of cutting edges 21.
[0057] The cross-sectional shapes can be centric or symmetrical with respect to the center point 17 of the tool 10.2, 10.3. Alternatively, the cross-sectional shapes can exhibit eccentricities with respect to the center point 17. The cross-sectional area of a tool 10.2, 10.3 with an eccentric cross-sectional shape tends to be smaller than the cross-sectional area of a cross-sectional shape arranged centrically or symmetrically with respect to the center point 17. The actual bending stiffness and the actual torsional stiffness of the eccentric cross-sectional geometry are therefore tend to be lower than those of the centric or symmetrical cross-sectional geometry.
[0058] Furthermore, the cross-sectional shapes differ in the shape of the transition edges that connect the cutting edges 21. These transition edges can be essentially flat, concave (i.e., curved inwards), or convex (i.e., curved outwards). The inwardly curved, concave geometry tends to have a smaller cross-sectional area than the flat and convexly curved cross-sectional shapes. Consequently, the actual bending stiffness and torsional stiffness are lower for a concave curvature than for a flat shape and even lower for a convex curvature.
[0059] The file set according to the invention, comprising files 1.2 and 1.3, is characterized by the cross-sectional shape of the tool 10.2, 10.3 for the specified diameter ds, by the material of the tool 10.2, 10.3, and by a heat treatment of the tool 10.2, 10.3 such that the actual torsional stiffness of the small tool 10.2 and the actual torsional stiffness of the large tool 10.3 are aligned, in particular by increasing the actual torsional stiffness of the small tool 10.2. Similarly, the actual bending stiffness of the small tool 10.2 and the actual bending stiffness of the large tool 10.3 are aligned. Here, in particular, the actual bending stiffness of the large tool 10.3 is reduced.
[0060] Three parameters are available for adjusting the actual bending stiffness and / or the actual torsional stiffness: the material, the cross-sectional geometry of the tool 10.2, 10.3 in the area of the working part 15, and a heat treatment to which the tool 10.2, 10.3 is subjected during manufacturing. For example, the tools 10.2, 10.3 can be made of stainless steel or a NiTi-based alloy. They can be tempered during manufacturing. Furthermore, the cross-sectional geometry can be adapted with respect to the cross-sectional area and shape, with the cross-sectional shape being influenced in particular by the number of cutting edges 21 and the transition edges between the cutting edges 21.
[0061] According to the invention, by appropriately adjusting at least two of the three setting parameters, the difference in the actual torsional stiffness of tools 10.2, 10.3 compared to the difference in the target values for minimum torsional stiffness specified in columns 3 to 11 of Fig. 7 according to the DIN EN ISO 3630 series of standards is reduced. Similarly, the difference in actual bending stiffness compared to the difference in the standard target values for maximum bending stiffness of tools 10.2, 10.3 specified in columns 3 to 11 of Fig. 8 is reduced. Overall, this makes it possible to keep the variance of tools 10.2, 10.3 of the file set low with respect to both actual torsional stiffness and actual bending stiffness. The treating dentist will therefore notice fewer differences when using the various tools 10.2, 10.3 of the file set.
[0062] Figures 9a to 9j show another file set according to the invention, comprising a total of five files 1.4, 1.5, 1.6, 1.7, 1.8. Each file 1.4, 1.5, 1.6, 1.7, 1.8 of the file set provides a tool 10.4, 10.5, 10.6, 10.7, 10.8 of the same length 11 and a shank 2.4, 2.5, 2.6, 2.7, 2.8 for receiving the files 1.4, 1.5, 1.6, 1.7, 1.8 in the dental instrument (not shown). The various tools 10.4, 10.5, 10.6, 10.7, 10.8 of the file set are designed, through a suitable choice of material, a suitable heat treatment and an adapted cross-sectional geometry, such that the amount of the difference in the actual torsional strength and the amount of the difference in the actual bending stiffness are each less than the amount of the difference in the standard specified values for the minimum torsional strength and the amount of the difference in the standard specified values for the maximum bending stiffness.
[0063] The setting of the actual bending stiffness and the actual torsional stiffness of tools 10.4, 10.5, 10.6, 10.7, and 10.8 is illustrated by means of their cross-sectional geometry. The cross-sectional shape of the working part 15 of tools 10.4, 10.5, 10.6, 10.7, and 10.8 is chosen such that the number of cutting edges 21 decreases with increasing diameter. The smallest tool, 10.4, therefore has four cutting edges, while the second smallest tool, 10.5, has three. The three other tools, 10.6, 10.7, and 10.8, each have two cutting edges. The middle tool, 10.6, and the second largest tool, 10.7, have a symmetrical S-shape, and the largest tool, 10.8, has an eccentric S-shape to further reduce the cross-sectional area. The middle tool 10.6 is more bulbous than the second largest tool 10.7.
[0064] Identical components and component functions are identified by the same reference symbols.
[0065] marked. Reference numeral list
[0066] 1.1 File
[0067] 1.2 File
[0068] 1.3 File
[0069] 1.4 File
[0070] 1.5 file
[0071] 1.6 File
[0072] 1.7 File
[0073] 1.8 file
[0074] 2.1 Shaft
[0075] 2.2 Shaft
[0076] 2.3 Shaft
[0077] 2.4 Shaft
[0078] 2.5 shaft
[0079] 2.6 Shaft
[0080] 2.7 Shaft
[0081] 2.8 shaft
[0082] 3. Conicity marking 4. Color marking
[0083] 5 stoppers
[0084] 6 Recording contour 7 Mounting surface
[0085] 8 Ring segment groove 10.1 Tool
[0086] 10.2 Tools
[0087] 10.3 Tools
[0088] 10.4 Tools
[0089] 10.5 Tools
[0090] 10.6 Tools
[0091] 10.7 Tools
[0092] 10.8 Tool 11 Length
[0093] 12 Longitudinal direction
[0094] 13 Transition section
[0095] 14 Ring marking
[0096] 15 Work section
[0097] 16 top
[0098] 17 Center
[0099] 18 Cutting edge envelope
[0100] 19 Rotational diameter 20 Taper
[0101] 21 cutting edge
[0102] 22 Circumferential direction
[0103] a cutting angle
[0104] do tip diameter
[0105] d3 Determination diameter h Determination distance
[0106] P Cutting distance
Claims
Patent claims 1. Endodontic file set for root canal preparation comprising at least two files (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8) each with a tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) extending in a longitudinal direction (12) and a shaft (2.1, 2.2) receiving the tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) formed for inserting the file (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8) into a receptacle of a dental instrument. 2.3, 2.4, 2.5, 2.6, 2.7, 2.8), - wherein all tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set have a conical working part (15) of any type with at least one cutting edge (21) and a different determining diameter (d3), - wherein the determining diameter (d3) of the tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) is in a range of 0.06 to 0.564 mm and - wherein an amount of a difference in actual bending stiffness and / or an amount of a difference in actual torsional strength between at least individual tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set is less than an amount of a difference in maximum bending stiffness determined from the standard specifications and / or an amount of a difference in minimum torsional strength determined from the standard specifications for these tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8), wherein, to adjust the actual bending stiffness and / or the actual torsional stiffness of each tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8), its material and / or its heat treatment during manufacture and / or its cross-section are adapted with respect to a cross-sectional shape and / or cross-sectional area, and wherein the tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set differ with respect to at least two of these three adjustment parameters.
2. Endodontic file set according to claim 1, characterized in that the amount of the difference in flexural stiffness and / or the amount of the difference in torsional strength between all tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set is less than the amount of the difference in maximum flexural stiffness and / or minimum torsional strength between the tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) determined from the standard specifications.
3. Endodontic file set according to claim 1 or 2, characterized in that the at least two tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) differ with respect to all three setting sizes.
4. Endodontic file set according to one of claims 1 to 3, characterized in that the difference in actual torsional stiffness between two and preferably between any tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set, based on the defined diameter (d3) of these tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8), is a maximum of 30 mN m per mm, preferably less than 20 mN m per mm, and particularly preferably less than 10 mN m per mm, and / or that the difference in actual bending stiffness between two and preferably between any tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set relating to the determining diameter (d3) of these tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) is a maximum of 40 mN m per mm, preferably less than 20 mN m per mm, more preferably less than 10 mN m per mm and particularly preferably less than 5 mN m per mm.
5. Endodontic file set according to one of claims 1 to 4, characterized in that each tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set complies with the standard specifications with regard to maximum flexural stiffness and minimum torsional strength.
6. Endodontic file set according to one of claims 1 to 5, characterized in that the conical working part (15) of at least individual tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set has two or more cutting edges (21) arranged distributed in a circumferential direction (22).
7. Endodontic file set according to one of claims 1 to 6, characterized in that at least one tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set is made of a NiTi-based alloy.
8. Endodontic file set according to claim 7, characterized in that the NiTi-based alloy provides further alloying elements.
9. Endodontic file set according to claim 8, characterized in that the NiTi-based alloy is designed as a ternary or quaternary NiTi-based alloy, wherein zirconium, chromium, hafnium, gold, manganese, vanadium, iron, cobalt and / or copper are preferably provided as further alloying elements and wherein a NiTiCr or NiTiCu or NiTiCuCr alloy is particularly preferably provided.
10. Endodontic file set according to one of claims 7 to 9, characterized in that the at least one tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) with the NiTi-based alloy has an austenitic microstructure at a tooth root temperature and preferably at room temperature.
11. Endodontic file set according to one of claims 1 to 10, characterized in that at least one tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set is made of a high-strength steel.
12. Endodontic file set according to one of claims 1 to 11, characterized in that at least one tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the file set is subjected to heat treatment during manufacture such that it is tempered at a temperature in the range of 250 to 550 °C for a duration of 5 to 240 minutes.
13. Endodontic file set according to claim 12, characterized in that the duration of the heat treatment is 5 to 30 minutes and the temperature of the heat treatment is 450 °C ± 250 °C.
14. Endodontic file set according to one of claims 1 to 13, characterized in that at least one tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the endodontic file set has a cross-sectional shape in the working part (15) that changes in the longitudinal direction (12), wherein the shape of the contour edges formed between the cutting edges (21) changes with increasing distance from a tip (16) of the tool (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8), preferably from convex to concave.
15. Endodontic file set according to one of claims 1 to 14, characterized in that at least individual tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) of the endodontic file set provide a different number of cutting edges (21).
16. Endodontic file set according to one of claims 1 to 15, characterized in that at least one fewer torque cut-off value is defined for the file set than the number of tools (10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) in the file set and that preferably only a single, uniform torque cut-off value is provided for the file set.