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Views: 0 Author: Site Editor Publish Time: 2020-10-01 Origin: Site
Endodontic files play an important role in the treatment of endodontics. Why is it accepted by the stomatology community? How did the endodontic file develop into its current state?
Why are endodontic files widely used in medicine?
Development history of endodontic files
What is the difference between endodontic files?
Cutting of hard tissue of teeth is an integral part of dental restoration. In the preparation before dental pulp treatment, it is also necessary to cut dentin and invest a lot of commercial investment to develop a flexible cutting instrument based on Niti Protaper Gold heat-activated. Endodontic files are constantly evolving, including the materials used (for example, the transition from stainless steel to Niti Protaper Gold heat-activated) as well as the design of the actual instruments themselves and their manual or electric drive methods. Over the past 25 years, we have examined the interaction of tooth cutting microscopically using various microscopic techniques. Especially the video rate confocal microscope. This provides us with unique insights into many of the procedures that we take for granted in clinical practice, by displaying microscopic video images of the cuts that occur in the teeth. Now, this technology has been expanded to allow imaging of endodontic instruments and root canal walls for the first time. We are able to image the dentin deformation and crack growth during root canal filling. We are also able to visualize the movements of contemporary dental pulp treatment devices that are often claimed but rarely seen.
Since the earliest records of dental pulp treatment instruments can be traced back to the 19th century, the basic concept of root canal preparation has remained unchanged. A series of narrow and tapered metal "braches" with cutting edges on their sides, which can be rotated (punching motion) or entering and exiting (punching) in the canal. These manual or electric metal cutting instruments are called endodontic files, and their design, materials and cutting performance vary greatly. Until recently, stainless steel (a hard alloy) was the most commonly used material for making endodontic files. However, the physical properties of machined endodontic files depend on the alloy composition, size (diameter) and geometry of the file. The elastic modulus of the stainless steel file is about 340±30 GPa, and its hardness is about 6.5±0.5 GPa. According to the requirements for dentin cutting (hardness is about 0.5 GPa [17]), the use of stainless steel with higher hardness exceeds the actual need. When it comes to elasticity, stainless steel files are too hard to follow the complex root canal structure. With a high modulus of elasticity, rapid stiffness as the document gets larger with undesirable overcutting of dentin, may result in more abnormal formulations and adverse meter results. This problem is apparent when measuring a curved root with a large, hard file. When the file tends to return to its original shape, applying more force on the side will cause excessive dentin cutting at the outer curvature of the root .
Over the past two decades, stainless steel has been gradually replaced by the more elastic alloy NiTi. William Buehler and Frederick Wang developed Nitinol or Nitinol in 1959. Niti taper file is a superelastic alloy composed of nickel and titanium in the same atomic ratio. NiTi was first used as an orthodontic arch wire for orthodontics in dentistry in 1971. In 1988, the first Niti taper file was produced as a manual file, but due to its excellent flexibility, Niti taper files are also widely used as motor-driven instruments, and stainless steel instruments will fatigue and break if continuously mechanically rotated. NiTi's mechanical properties depend on its crystallographic arrangement, temperature and stress, and it may exist in two forms. At higher temperatures, NiTi exists in the austenite phase, where the atoms are arranged in a cubic lattice centered on the body. When applied stress or temperature drops below a certain range (called the transition temperature), atoms tend to rearrange their distribution into a more elastic form, called the martensite phase. This transformation makes NiTi superelastic. The elastic modulus of austenite NiTi is 120 GPa, which is much higher than that of stainless steel, and it can be transformed into a more elastic martensite phase under stress, with an elastic modulus of 80 GPa.
In order to reduce unnecessary dentin cutting that may affect the treatment results, improved root canal preparation techniques are needed to promote the development of endodontic instruments. Therefore, Niti Protaper Gold heat-activated has become the first choice for manufacturing alloys due to its superelasticity and low hardness (about 3.17±0.2 GPa [16]). This allows curved tubes and complex anatomy to be negotiated better, and minimizes the lateral transfer of applied stress into dentin. Development also includes other aspects, such as design and manufacturing procedures.
Endodontic files are manufactured using two main processes, either by mechanical grinding of tapered wires or by a combination of grinding and twisting. stainless steel files are usually manufactured using two techniques. However, due to the superelasticity of this material, for NiTi, twisting was obviously not applicable at first. However, after special heat treatment of the alloy, a twisted Niti taper file will be produced. Other advances in the manufacture of Niti taper files involve thermomechanical machining, a process that allows the use of these files in the martensite phase, thereby providing a new generation of files with improved performance. By examining the lateral cutting portions of these files, the cutting characteristics of the endodontic instrument can be more easily seen. In some designs, the taper may be variable rather than fixed. Since the taper is related to the diameter, the taper will seriously affect the rigidity of the endodontic file. The higher the taper, the less flexible the file. Therefore, some endodontic file designs increase the depth of the chip flute, thereby reducing the amount of metal on the central axis of the file, thereby minimizing the effect of rigid metal on the file's flexibility.
When using stainless steel K-type files, the cutting movement can be performed in two ways. Rotational movements (perforation) can be performed to allow the inclined cutting edge of the file to be used in a horizontal motion, or the file can be used for “file” movement in and out, which uses an inclined cutting edge in vertical motion. Cutting in these ways can be regarded as a free diagonal, where the cutting edge is inclined at an angle. When using a positive rake file for instrument installation, the cutting begins by piercing the cutting edge of the rotating file into the dentin dentin surface. This will begin elastoplastic deformation until the force applied by the file exceeds the shear strength of the dentin and causes the dentin fragments to flow away from the rake surface. Through this cutting action, the surface infected dentin is removed, exposing a deeper layer of bacteria, which allows the chemical disinfectant to penetrate deeper
In conclusion, research on the performance and cutting efficiency of different types of endodontic files and instruments is essential to understanding their impact on mechanical dentin. From manual instruments made of stainless steel to rotationally powered Niti taper files, endodontic files have undergone continuous development , If you are looking for a high-quality endodontic file at a reasonable price, Osakadent Co.,Ltd. will provide you with the best products.
