Among all the endodontic instruments are the root canal preparation files. As time goes by, their technology advances and new and better files are designed to be able to treat each clinical case with greater precision and comfort.
It is true that the big question for dentists is which system is more complete, but lthe answer is that there is no such thing as a perfect system.
Depending on the clinical case we are treating, one instrument or another will be used, in addition to the fact that it also depends a lot on the endodontist's methodology, since there are some that are more conservative than others. Many endodontists even alternate and combine manual files since K files are still more practical and necessary, with mechanized files that are more expensive and fragile in the distal segments.
Introduction to Endodontic Files
Before we begin with the central theme of the post, the manual files, we remind you the most important parameters to consider about endodontic files:
Classification Endodontic instruments are divided into 4 groups:
- GROUP 1. Instrumentation to prepare the canal manually.
- GROUP 2. Instrumentation to prepare the duct in a mechanized or rotary manner.
- GROUP 3. Trephines to be used mechanically (Weight burs, Gates glidden, etc.).
- GROUP 4. Instruments and materials for sealing the duct (paper cones, condensers, etc.).
Number of instruments in each system.Depending on the manufacturer, some files will have more intermediate numbers or different tapers.
ISO Classification. Not all files meet the requirements for this classification. To be part of it, they must meet the following:
- The caliber of the file is numbered from 10 to 100, with jumps from five units to size 60 and jumps from ten units to size 100.
- The cutting edges start at the tip of the instrument with the so-called diameter 0 (D0) and extend exactly 16 millimetres to the stem, ending at diameter 16 (D16).
- The diameter of D16 will be 32/100 or .32 mm larger than that of D0.
- These measures ensure a constant increase in taper of 0.02 mm. for each instrument regardless of size.
- The angle at the tip should be 75º ± 15º.
- The numbers 6 and 8 were added more recently for greater versatility.
Type of cut and section
Number of uses of each. It is important to know how many times a file can be used to avoid fractures and accidents. Manufacturers recommend discarding the instrument after the first use, but it is true that many times this is not put into practice because of the cost.
There is no exact rule for calculating the number of uses of each file. But in order to anticipate the fracture, the following must be taken into account:
- The state of the conduit to be treated. The more curved the duct, the more the file will be forced.
- The stress to which the file is subjected. It is necessary to know the properties of the NiTi material as well as possible. The manufacturers of these instruments recommend a maximum of 8 conduits (not teeth) if they are straight and smooth, and reducing the number of uses as the conduit becomes more difficult, but it is necessary to observe the file well before proceeding, and when the first doubt discards it.
- It is not the same to use thick and resistant files as it is to use fine and flexible ones. Ideally, ducts can be classified as easy, medium and difficult, but there are many shades in between. Of course, in difficult ducts the files will be changed before the easy ones, but you should not always follow this rule.
In conclusion, each time a file is used, it must be carefully observed. The final decision is made by the dentist.
Active or inactive tip? Depending on the case, one or the other will be used, although the inactive tip is safer since with it it is more complicated to perforate the conduit by the passivity of its force in the cut, while the active tip has a greater cutting edge in the cusp.
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Manual Endodontic Files
Below we detail all the manual files with their main characteristics:
1. K files
The most used to prepare the root canal. Over time they have varied from square section to triangular and rhomboidal, giving rise to the files K-Flex and Flex-R.
- From 1.97 to 0.88 cutting striations per millimeter.
- Helical angle of 45°.
- Available in 21, 25 and 31 mm lengths.
- From caliber 6 to 140.
- Twisted instrument.
2. Flexofile Files
Hybrid instrument derived from K files with triangular section.
- With cutting angle of 60° and more.
- Inactive, safer and less aggressive point.
- From calibre 6 to 140 (21mm and 25mm).
- Twisted instrument.
3. K-Flex Files (Kerr)
- Rhomboid stem
- They facilitate the elimination of detritus by increasing the free space between the file and the dentin wall.
- Sharp rhombus angles improve cutting efficiency.
- From calibre 6 to 80.
- Twisted instrument.
4. Flex-R Files/h3>
Instrument derived from cordoned K files.
- With sharper striations.
- Cutting angle is more negative than in a traditional K-file and twisted.
- Roane eliminated the transition angle of the tip, which makes it easier to follow the duct without producing steps.
- Twisted instrument.
5. K-Colorinox Files
They are made of high quality steel from Sweden very fine and stainless. Manufactured by torsion, it gives them a high resistance to fracture, keeping their metal fibers intact. They enlarge the root canal, either abrasively or shear.
- It has an active cutting tip.
- Available in 21mm, 25mm, 28mm and 30mm in gauges from 06 to 140. and .02 taper.
- Quadrangular stem
Root canal exploration file. Available in 18mm, 21mm and 25mm lengths and 8-15 gauges.
7. C-Pilot files
VDW C-Pilot files are special endodontic files for particularly sinuous and calcified ducts.
- Available in three lengths: 19mm, 21mm and 25mm.
- Inactive tip.
- Intermediate size ISO 12.5.
- Cross section.
8. Triple Flex Files
Unlike turned files, the Triple-Flex is highly resistant to breakage, even in high-tension situations. Linked instrument.
9. Flexicut Files
For the treatment of narrow, highly curved root canals with a filing motion.
- Triangular section and inactive tip.
- Stainless steel.
10. Hedströem Files
Drags large quantities of fabric in its cut by traction.
- It has a helocoidal shape.
- Turned instrument.
- They cut in only one direction, of retraction, due to the positive inclination of their grooves.
11. UltraFlex, Uniflex and Unifile files
Less known and more specific. Turned instrument. The files of the Unifile system have been manufactured by turning.
12. Reamers (Reamer)
It has the characteristic of producing a passive remolition. It will have from 0.80 to 0.28 cutting grooves per millimeter in its part. Triangular transverse configuration. Functions:
- To widen the conduit in a uniform and progressive way.
- Remove material from the duct.
13. Nerve puller
Progressively in disuse since it is very aggressive, it is used only in cases of very wide ducts.
Not so fast! There are still the rotating files.Click here to know the most important thing about them in a very visual article with punctual and practical content.
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