Know More About Endodontic Files 

 Types of Endo files:-

There are 3 types of file systems such as: 

  • Flex R File
  • Safety H Files
  • Rotary File System 

Flex R File -

The invention of Flex R File was back then when Powell noticed that the straight stainless steel tips of the files could only increase the tendency of the transport or ledge and eventually to perforate curved canals at the outer wall which is a convex curvature of the canal. It was then when Powell pointed out that the reduction of tip angle could help the file to focus on the original canal and could cut the edges or the sides evenly. This modification of the tip brought in the Flex R File.    

 The tip was modified and a triangular file design was given to Flex R File. The cross-section area of the file is 37.5% less to that of the square file of the same size which gave the flexibility to the file’s tip.

The curved canals produced a concentrated parabolic tip which removes the elastic deformation of the instrument in a concentrated area and helps in the distribution of the forces in cutting the flutes. This helped in reduction of canal transportation during canal preparation.     

Flex R File has a balanced force technique. It has reduced the procedural accidents as the tip is rounded and safe. These files are sharper and have less negative rake angle. The modification has allowed greater control of strength and flexibility by controlling the cutting edge and cross-sectional area of the metal bulk. The file cuts in anti-clockwise rotary motion. It increases carrier effect i.e it carries more amount of debris out of the canals. 

 

Safety H Files

Safety Hedstrom Files were designated by Buchanan and was introduced by Kerr Manufacturing in 1993. It is now being marketed in as ISO 15 to 40. 

 The modified tip of Safety H Files and the non-cutting sides has turned them to be successful. The non-cutting smooth edges prevent ledging in the curved canal. The file has to be directed according to the curvature of the canal. Safety H Files ensures safety with enhanced efficiency for filing or reaming. These files are specially designed for retreatment

The spiral design of the flute increases depth and length from tip to handle. The cross-sectional shape of the file is ‘S’ in shape because of which these are also called S Files. It is used in linear motion and prepares the canal without ledging it. These files do not remove excess materials from the outer wall. 

Colour code for all the endo files (which includes all the K-files, H-files and Reamers) remains the same whereas the length of the files come in three sizes such as 21mm, 25mm and 31mm. The colour variants come in 9 shades i.e Pink, Gray, Purple, White, Yellow, Red, Blue, Green and Black. 

Gutta- Percha Points for all the files comes either in percentage or in points which could either be like in 2%, 4% and 6%. 

Paper Points are used to dry the root canal post preparation and irrigation. These files are highly absorbent, sterile and merely contain any adhesive. These points come in 0.2, 0.4 and 0.6.

Rotary File System

A Rotary File System is a cylindrical or modified cylindrical form that rotates rather than reciprocating motion. Rotary File System was introduced in early 2001. 

These files are used with an endodontic handpiece in an ordered sequence. These files were made up of materials like carbon, stainless steel and nickel-titanium alloys (NiTi Files).

Rotary File System was accepted widely as they improved the safety and consistency of results. Hence, improving its efficiency and procedural simplicity.

NiTi File System

NiTi File System brought in an era to the world of Endodontics. NiTi Files are made up of nickel and titanium alloy. The elasticity of nickel and titanium allows it to return to its shape following a significant deformation, making the endo files more flexible and are able to conform to canal curvature, resists fracture. NiTi files are engine-driven tapered and pointed endodontic instruments where the cutting edges used to mechanically shape and prepare the root canals during endodontic therapy or procedure. 

NiTi Files are long-lasting and tend to wear less as compared to stainless steel and other materials.NiTi files have two specific designs that have increased the efficiency of the files and have put a tremendous impact on the shaping potential of files i.e the Cross-Sectional Design and Tip Configuration

There are few other components such as Helix Angle, which may change along the working surface added up with a measuring stop, measuring lines and a taper. 

NiTi files show superelasticity when put under stress undergoes to a state of martensitic transformation and on the release of stress, it gets back to an austenite form i.e it gets back to its original shape. The new prototype rotary motors have improved the torque control with an automatic reversal that has eventually decreased the breakage of rotary files. These are biocompatible having anti-corrosive properties. The invention of Radial Lands has allowed NiTi files to be used as reamers in a 360° motion. 

These properties of NiTi files have made a shift for the clinicians from using high torque instruments such as stainless steel to low torque instruments such as NiTi files which are more efficient and safe as compared to other file systems.

Profile - Series 29:

The series of instruments were introduced by Stephen Buchanan.

These file systems have tip diameter d1 and increase with sizes. 0.02 mm is for 6-10 size, 0.05mm is for 10-60, 0.1mm is for larger sizes respectively. The tip diameters differ from size to size such as for 10-15 sizes the difference is 50% and from 55-60 it is 9% only. 

A new size - 1 of profile 29 series corresponds to ISO size 10. 

These files are available in stainless steel as well as in NiTi hand instruments. They resemble NiTi “U” files having a narrow tip of 0.02mm. These instruments are spaced with more instruments with smaller sizes and fewer instruments at larger sizes. 

Profile GT Rotary Files (Great Taper):

Great Taper was introduced by Dentsply Maillefer, for cleaning and shaping. 

Profile GT comes with different great taper, sizes ranging from 0.06, 0.08, 0.10, 1.12 mm. 

According to Buchanan, these files are sized to fit a certain size of canals. They are variably pitched, radical lands clockwise cut U-blade that provides reaming like efficiency at the shank with K-file strength at their tips. Flute diameter is generally set at 1.0mm for safely limiting the coronal enlargement. 

ProTaper Rotary System -  

ProTaper File System includes six instruments in it. There are three shaping files and three finishing files

The shaping files are named as S-X, S-1, S-2. 

The finishing files are names as F-1, F-2, F-3. 

S-X

The auxiliary Shaping File X (S-X) has a length of 19mm providing excellent access in restricted areas. This file has a D0 diameter of 0.19mm of the partially active tip. 14 mm of cutting blades and D14 diameter of 1.2mm. The S-X has a much faster taper from D0 to D9 as compared to the other two shaping files. At approx D6, D7, D8, D9 the cross-sectional diameters are equivalent to 0.5mm, 0.7mm, 0.9mm and 1.1mm respectively. These files are used to optimally shape canals into shorter roots and relocate canals away from external root concavities and give more shape as desired in the coronal aspect in longer roots. 

S-1 and S-2 have D0 diameter of 0.17mm and 0.20mm diameters with partially active tip and their maximal full diameters of 1.2mm each. Each shaping file has 14mm of cutting blades. These files have increasingly larger tapers allowing each instrument to engage, cut and prepare a specific area of the canal.

S-1 helps in preparing coronal ⅓ of the canal whereas S-2 enlarges and prepares the middle ⅓. Both the shaping files prepare the ⅔ of the coronal, preparing and enlarging the ⅓ of the apical

The shaping files increase flexibility, Cutting Efficiency and reduces the number of   Recapitulations needed to achieve the length, especially in tight and curved canals. It also helps in reducing Torsional Loads, Fatigue and Breakage.  

The finishing files F-1, F-2, F-3 have been developed to address the variations in cross-sectional diameters that canals exhibit in their apical ⅓(s). The finishing files have the D0 diameters of 0.20mm, 0.25mm, and 0.30mm. Between D0 and D3 the taper differs from 0.7mm, 0.8mm and 0.9mm respectively. From D4 to D14 the files have decreased taper to increase flexibility. To improve its flexibility F-3 has reduced core as compared to other tapers. These are designed to optimally finish the apical ⅓, they too subtly and progressively expand and shape the middle ⅓ of the canal. Generally, only one finishing file is required to finish the apical ⅓ of the canal. It is selected according to the curvature and cross-sectional diameter.  

Protapers have a convex triangular cross-section that reduces the contact area between the file and dentine. The cutting efficiency has been balanced by the pitch and the helical angle. 

Generally, only 3 protaper files are required to produce a fully tapered canal that exhibits uniform shape over length. 

V Taper-

V Taper Rotary File System has three file series for different canal shapes i.e Large, Medium and Small canals.

V Taper gives the deeper apical shapes, conservative coronal preparations, natural-shaped canals than better stimulate the original anatomy. It also gives in better access for irrigating, cleaning and 3-D obturation. It has reduced overhead and inventory with better productivity.  

V Taper eliminates ‘taper lock’, it’s cross-section gives the best deep-hole reaming in the root canals. It is one of the specially made Niti files that reduces the risk of breakage with a short handle for better visibility and access.

The performance of the V Taper System is easier, safer, more efficient and cheap as compared to other NiTi Rotary files. These files help in carrying out the best root canals for molars and premolars with just 2-3 files. 

Quantec -

Quantec files are positioned in such a way that it opens the orifice and it allows the irrigant to permeate the canal. The tapers of the linework on different areas of the canal, such as the larger taper work towards the orifice whereas the smaller tapers work easily towards the apex. These files tend to work more efficiently at the coronal third of the canal. 

Quantec NiTi file systems have a taper from 0.02mm through 0.06mm with ISO tip sizes. The quantec flare series have tapers from 0.08mm, 0.10mm and 0.12mm of tip size. 

The files are designed in such a way that the rake angle of the taper helps in slightly shaving the dentine rather than scraping it off. The flute design of the file has a 30° helical angle making it larger distal to cutting blades. The wide radical lands help in preventing the crack formation in blades and aid in deflecting the instrument around the curvature.

There are two tip designs of Quantec files i.e SC - Safe Cutting Tip and LX - Non-Cutting Tip.

SC - Safe Cutting Tip is designed for small, tight canals, narrow curvature, and calcified canals. Then the tip approaches the curve, a balance takes place between the file deflections and cutting. 

LX - Non-Cutting Tip act as a pilot in the canal and deflecting around severe curvature in less constriction of canals. These files are recommended for enlarging the body and coronal segments and managing the delicate apical region

These increasing size of the tapers from 0.08, 0.10 and 0.12 with tip sizes of 150 25 are designed such to quickly and safely shape the coronal third of the canal. The varying sizes of taper are used to prepare single canal.

Golden - Mediums (Intermediate File):  

The introduction of these files was to avoid the errors such as ledging, zipping, transportation of apical foramen and perforation which eventually resulted from uncontrolled dentine removal. These files played an important role in providing smoother progress.

These files are numbered as 12,17,22,27,32 and 37. These files are a part of flexo file range. 

K3 FILE SYSTEM : 

K3 File System was designed by Dr. John and Dr. Mc. Spadden.

These taper files are available in size numbers through length, though they are fixed with taper size of 0.02, 0.04 and 0.06.

0.02 taper instruments come in sizes, No. 15 through No. 60 and 21, 25 and 30mm lengths. Similarly, for 0.04 and 0.06 taper instruments comes in sizes of No. 15 through No. 60 and 21, 25 and 30mm lengths. 

The positive rake angle provides a more effective cutting and the core diameter enhances the flexibility throughout the length of the instrument. It has a safe ended tip. The instrument prevents the screwing effect according to the variable pitch. The proportion of core diameter and the outer diameter is greater at tip hence making it stronger at the tip. As the fluting moves up the taper the greater flute depth increases with flexibility along with strength. 

K Files are made up of a wire of cutting into a tapered instrument ending at the tip giving its tip a square cross-section. These can be used in filling action or in reaming action. When the file is locked inside the canal the clockwise rotation it unwinds and gives ductile type fracture whereas in anti-clockwise rotation it leads to sudden brittle fracture. 

K Reamers have a triangular cross-section with loose spirals around the flute. They have a reaming motion. These are used to ream canals, they cut the canals by inserting into the canal by twisting clockwise one quarter to half turn and then withdrawing i.e penetrating, rotating and retracting

 

K - Flex File -

K - Flex Files has a cross-section of rhomboid shape and has more flexibility because of the twisted and series of alternate sharp cutting edges. It has obtuse non-cutting edges which increase the cutting efficiency as compared to other K-Files. These files work the best for the debris removal, the obtuse angles of rhombus create anger that helps in removing the debris to a large extent. It also reduces the danger of dentinal filling in the canal. 

Flexo File - 

Felxo File has a cross-section of triangular shape which gives a sharper cutting edge. These files are made up of stainless steel and do not have a cutting tip. These files have 29 spirals that gives more rooms for the removal of the debris. 

The stainless steel file gives extreme flexibility and resists fracture. The cutting angle is 30° at the tip and 45° at the working end. 

 

Twisted Files -

Twisted Files are the first NiTi fluted files that were manufactured by plastic deformation. It has a sizing tip from 25 to 50 and tapers from 0.04mm to 0.12mm. It is made from R - Phase™ technology. In these files, the NiTi alloys are twisted instead of being ground. 


Self Adjusting Files

Self Adjusting Files are designed with a hollow adaptive design with the help of Laser Miller Niti Lattice and Cardiac Stents. The abrasive design has the ability to become extremely flexible, pliable and adaptive. It does not impose its shape on the canal rather it complies with the canal’s original shape. These are elastically compressible, thin-walled pointed cylinder with 1.5mm in diameter with NiTi lattice. These files are capable to achieve complete 3D root canal shaping and cleaning. SAF applies continuous pressure along the entire circumference of the root canal wall. It has an excellent adaptation to irregular canal anatomy.

 

RaCe -

RaCe stands for Reamer with Alternating Cutting Edges. RaCe combines with SS and NiTi alloy for better versatility and is an active cutting instrument. RaCe was designed like reamers with loosely wound flutes which have less contact with the inner wall of the canal. Hence, less screwing effect. It reduces frictional resistance during rotation to a greater extent. 

The RaCe has a cross-section of straight-sided triangle which helps in better cutting effect. The sharpness of the non-cutting tip gives flexibility, less torque, and more control. It helps in preventing canal transportation. The RaCe gives in greater tapered preparation and is less time-consuming

 

NeoEndo Files - 

NeoEndo Files is a combination of Shape and Controlled Memory. It utilizes a heat treatment property which makes it a tough file with unique flexibility. The flutes of the files do not open up when the stress level is reached. It has a triangular cross-section. 

NeoEndo Files should be used gently without exerting pressure. While using NeoEndo Files the canals should be irrigated properly before engaging the files. These files are taken passively to the point of resistance and then are brushed out from the canal. 

These files come in various sizes for narrow, medium and wide canals with different sizes and taper sizes. 

 

WaveOne Single File System:

WaveOne NiTi Single File System is specially designed as it works in a reciprocal motion in a reversed balanced force action. 

These files are manufactured with M-Wire technology improving strength which helps it to resist cyclic fatigue. The files have a modified convex triangular cross-section at the tip end as well as in the coronal end. Hence improving the flexibility. The tips help in following the canal curvature accurately. 

These files come in three sizes i.e Small files with ISO 21 with a continuous taper of 6%, Primary files with ISO 25 with an apical taper of 8% which reduces towards the coronal end and Large files with ISO 40 with an apical taper of 8% that reduces towards the coronal end.

 

Hero Shaper -

Hero Shaper is micro mega NiTi files that were initially designed with a slightly negative rake angle and were neutral. But the advancement of NiTi files and they were redesigned with a positive rake angle hence giving them a nice cutting efficiency. It was originally known as Hero 642 which has now been renamed as Hero Shaper. 

Hero Shaper comes in two sizes with various lengths and colours. It comes in red, blue and yellow in colour. It comes in two flute lengths i.e 12mm and 16mm with 21mm, 25-29mm and 21-25mm. It comes in two taper sizes of 0.06 and 0.04.

Red denotes n 25, blue denotes n30 and yellow denotes n20.

Hero Shaper work on up and down movement with circumferential fillings. It irrigates the canal between the passage of successive instruments. Files have 3 edged tips with positive rake angle and big inner core for excellent resistance of breakage. These instruments unwind to prevent fracture. 

Hero Shapers have better-centring ability as compared to other files.

The cross-section of Hero Shaper is similar to H-files but without radical lands. These files have elasticity in rotation with high flexibility.

 

HyFlex Rotary Files -

Hyflex Rotary Files works on the property of thermo-mechanical treatment. It retains its shape after bending. It has good superior canal tracking ability. It regains its shape after sterilization. These files are used to enlarge the canal to prepare it for irrigation and obturation in continuous rotation motion or if required in reciprocal motion as well. The files are available in different sizes depending on the tip size of the file. It also has colour codes to indicate the degree of the taper. The new NiTi heat-treated files are manufactured making it fracture-resistant and flexible. These files can be used multiple times and can be restored during autoclaving. 

Hyflex Files are of various types:

Hyflex™ EDM NiTi Files

These files belong to the 5th generation of the root canal files. In the process of making of Hyflex ™ EDM files, the surface material evaporates when the spark is generated. Hence, making the file stronger and fracture-resistant. These properties help in reducing the number of files required during the cleaning and shaping of the root canal treatment keeping the root canal anatomy intact. 

Hyflex™ CM NiTi Files -

Hyflex™ Controlled Memory Files are manufactured in a process that controls the material’s memory. These are extremely flexible files, enabling the ability to follow the anatomy of the root canal very closely, reducing the risk of ledging, transportation or perforation. They can be bent and are very useful for the root canals with abrupt curvatures. This property of the file to reshape it according to the need of the curvature helps in root canal treatment plus it can be straightened by heat treatment. It also strengthens the file making it resistant to cyclical fatigue.

Hyflex™ GPF NiTi Files

These files ensure the optimal shaping of the glide path due to the controlled memory.     

Hyflex™ NT NiTi Rotary Files -

These files are designed for specific clinical usage such as calcified canals, straight canals, retreatments and removing GP. They are available in two taper variation i.e 0.06 and 0.04 with 21mm, 25mm and 31mm length.