Endodontic Instruments

A quick and concise recap of Endodontic Instruments.
This presentation resolves the basic doubts within terminologies and provides visual conceptualization of the same.

1. Endodontic nstruments Presented by : Ishaan Adhaulia

2. Introduction Instruments play a very important role in the success of a root canal treatment therefore a basic knowledge of endodontic instruments is essential. General guidelines exist for root canal preparation, but due to the complex and varied canal anatomy each case presents unique challenges. A variety of instruments are thus available for this purpose.

3. Classification of Instruments

4. Standardization of Instruments Ingle & LeVine’s Original Recommendations Files are numbered from 15 – 60 with an increment of 5 From 60 onwards the increment is 10 Cutting blades 16 mm in length (I 1 ) The diameter of the instrument at tip (D 1 ) is determined by size in hundredths of millimetres. Diameter at D 2 is uniformly 0.32 mm greater than D 1 ensuring a constant increase in taper of 0.02mm/mm Length of entire file blank - 25mm (I 2 )

5. Modifications in Standardization Four modifications were made in Ingle & LeVine’s original proposed recommendation: Additional measurement at D3 , 3 mm from tip (D1) Specification for angles of the tip: 75 degrees, ± 15 degrees Number 6 & 8 have been added for increased instrumentation Colour coding added for quicker identification of diameters of files.

6. Before diving into the classification, let us review the components of an endodontic file.

7. Taper It denotes the per millimetre increment in file diameter from the tip towards the file handle. There are files with variable taper such as,

8. Core It is the central cylindrical part of the file having its circumference outlined and bordered by the depth of the flutes.

9. Flutes It is the groove in the working surface used to collect soft tissue and dentin chips, removed from the walls of the canal. The effectiveness of the flute depends on its depth, width, configuration, and surface finish. FLUTE

10. Cutting Edge The surface with the greatest diameter that follows the groove (where the flute and land intersect) as it rotates, forms the leading (cutting) edge, or the blade of the file. Cutting Edge (Yellow)

11. Radial Land / Marginal Width Flat cutting surface present between two flutes/grooves The land touches the canal walls at the periphery of the file and reduces the tendency of the file to screw into the canal Reduces transportation of the canal & propagation of micro-cracks on its circumference Supports the cutting edge & Limits the depth of cut. Radial Land indicated between two black arrows.

12. Relief / Helix Angle Relief : Surface area of land that is reduced to a certain extent to reduce frictional resistance. Helix angle : It’s the angle, the cutting edge forms with the long axis of the file. All debris is collected in the flute from the canal. This angle is important for determining which filing motion to use.

13. Rake Angle It is the angle formed between the leading edge and the radius of the file If the angle formed by the leading edge and the surface to be cut (its tangent) is obtuse, the rake angle is said to be positive or cutting . If the angle formed by the leading edge and the surface to be cut is acute, the rake angle is said to be negative or scraping

14. Pitch The pitch of the file is the distance between a point on the leading edge and the corresponding point on the adjacent leading edge.

15. Filing Motions 1) Reaming - A quarter turn clockwise and apically directed pressure Used with a reamer 2) Filing Push & Pull motion of an instrument 3) Combination of reaming and filing File is inserted with a quarter turn clockwise and apically directed pressure (i.e. reaming) and then is subsequently withdrawn (i.e. filing) 4) Watch Winding - It is a back and forth oscillation of the endodontic instrument right and left as it is advanced into the canal Reaming Filing Reaming & Filing Watch Winding

16. Filing Motions Circumferential Filing Used for canals that are larger and are not round. The file is placed in the canal and withdrawn in a directional manner sequentially against the mesial , distal, buccal and lingual walls Balanced Force Technique - It’s the best technique as it involves clockwise rotation of instrument for 90 degree, then counter-clockwise rotation of instrument with apical pressure (we will hear a clicking sound) for 120 degrees, then a final clockwise rotation and the instrument is withdrawn.

17. Group 1 – Hand Operated Instruments Barbed Broaches Barbed broaches are short-handled instruments used primarily for vital pulp extirpation . They are also used to loosen debris in necrotic canals or to remove paper points or cotton pellets. These instruments are manufactured by notching a round, tapered wire with a blade to form sharp, projecting barbs that cut or snag tissue. SMOOTH BROACH

18. Rasps Broaches and rasps show some significant differences in taper and barb size. The broach has lesser taper of 0.007 to 0.010 mm and the rasp has more taper of 0.015 to 0.020 mm. Barb height is much greater in the broach than in the rasp.

19. Kerr Files (K-Files) In 1904 Kerr Manufacturing Company designed the, K-style files and reamers. K-files were manufactured by twisting square or triangular metal blanks along their long axis, producing partly horizontal cutting blades. The tip is cutting and pyramidal Helical angle: 40˚

20. Kerr Reamers (K-Reamers) Reamers cut and enlarge canals with rotational motions . K Reamers have a rake angle which makes them most efficient in rotary motion , hence reaming is preferred. K-Reamers have larger and less number of flutes compared to K-Files.

21. K-File /Vs/ K-Reamer K-File (Triangular Cross section) K-Reamer (Square Cross Section)

22. Modified K-Files K-Flex File The Kerr Manufacturing Company in 1982 introduced a new instrument design that they termed the K-Flex File. The cross-section of the K-Flex is rhombus or diamond shaped . This new cross-section presents significant changes in instrument flexibility and cutting characteristics Rhomboid shape gives the file 2 cutting edges and 2 non-cutting edges which increase the chip space .

23. Flex-R by Roane (1985) The Flex-R file by Roane (1985) is the first to utilize a non-cutting tip that helps avoid ledge formation in curved canals. The principle of the Flex-R is based upon removal of the sharp corners at the instrument tip (dual conical form).

24. C – File ( Mallifer ) These are made of specially treated stainless steel for stiffness and strength. The result is easier access to challenging, calcified canals. Heat-tempered steel for stiff performance Twisted file design for greater strength Eases penetration of calcified canals Available in 21 mm & 25 mm

25. Hedström File (H-File) Hedström files are milled from round stainless steel blanks. Cutting action: Retraction They are very efficient for translational strokes, but rotational working movements are strongly discouraged because of the possibility of fracture. Helical angle: 60˚ Better cutting action than K-file (more positive rake angle).

26. Modifications of H-File McSpadden was the first to modify the traditional Hedstroem file. Marketed as the Unifile and Dynatrak , these files were designed with two spirals for cutting blades, a double-helix design & a triple helix design in HeliFile S – File can be used with any hand motion (filing or reaming) thus this file can also be classified as hybrid design S - file HeliFile

27. Group 2 – Low Speed Instruments with latch type attachment Gates Glidden Drills This has a long, thin shaft ending in a flame-shaped head with a non-cutting safe tip to guard against perforation.’ They are used to remove the lingual shoulder during access preparation of the anterior teeth & to enlarge orifices . It is made of hardened carbon steel. The flame shaped head cuts laterally and is used with a gentle, apically directed pressure . It has a modified safe tip i.e. non-cutting tip. These instruments come in sizes 1 to 6

28. Peeso Reamers It has long sharp flutes with a safe tip connected to a thick shaft . It should be used at slow speed , as they cut aggressively and are inflexible It cuts laterally and is primarily used for the preparation of post space when gutta-percha has to be removed from the obturated root canal.

29. Group 3 – Engine Driven Instruments Nickel Titanium Rotary Endodontic Instruments These instruments are made up of Nitinol, an equi-atomic alloy composed of nickel and titanium They exhibit “ shape memory ” due to austenitic crystalline structure transforming into martensitic crystalline structure under stress . NiTi flex - files are manufactured from nickel-titanium wire that is ground to give the typical profile of a K-file. The tip of the instrument is non- cutting (' batt -tip') which makes the NiTi flex - file, well suited for the preparation of curved canals without the risk of ledge formation. NiTiflex -files come in sizes 15 - 60, all with a taper of 0.02.

30. Reciprocating Instruments They function at unequal bidirectional angles The novel reciprocating movement allows a file to progress more readily, cut efficiently, and effectively auger debris out of the canal Eg : WaveOne system and Reciproc Reciproc Files

31. Self Adjusting File Introduced by Zvi Metzger The file three dimensionally adapts both longitudinally and along the cross-section of the root canal system (characteristic feature) This results in a uniform cutting action of the dentin from the canal walls (60-75 µm thick) and preserves the basic shape of root canal. File maintains the canal cantering ratio and stays within the canal & maintains the canal anatomy.

32. Group 4 – Ultrasonic Hand Instruments The first ultrasonic instrument goes back to Richman (1957) The ultrasonic instrument consists of a piezoelectric or a magnetostrictive unit that generates ultrasonic waves The piezo -electrical units are better in that they are more powerful and generate lesser heat than the magnetostrictive systems . The hand-piece holds a K-file or a specially designed diamond file that, produces movements of the shaft of the file between 0.001 and 0.004 inch at a frequency of 25–30 kHz

33. Sonic Instruments Sonic hand-pieces operate at 2–3 kHz when used inside root canals. They are similar in shape and weight to dental hand-pieces and are attached to existing air and water lines. These instruments are used in a manner similar to the ultrasonic system in instrumentation of the root canals. The only difference is that the sonic system uses water as an irrigant and requires special instruments known as: Rispi Sonic Shaper sonic Trio sonic (or Helio sonic)

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