rotary instruments in endodontics
- 1. ROTARY INSTRUMENTS IN ENDODONTICS Dr Gurmeen Kaur II MDS, Department of Conservative Dentistry and Endodontics, A B Shetty Memorial Institute of Dental Sciences, Mangalore.
- 2. Contents ■ Introduction ■ History ■ Classification of Endodontic Instruments Based on Method of Use – Low-Speed Instruments with Latch-Type Attachment ■ Gates-Glidden drills ■ Peeso Reamers – Engine-driven instruments ■ Rotary NiTi endodontic instruments ■ Reciprocating instruments ■ Self-adjusting file (SAF) ■ Material Science ■ Properties of NiTi ■ Comparison of Properties of NiTi and Conventional Stainless Steel ■ Mechanics and Design Features ■ Nickel-Titanium Rotary Instruments ■ Generations of Rotary instruments
- 3. ■ Design features of current rotary NiTi file systems ■ ProFile GT andGTX ■ Lightspeed LSX ■ ProTaper ■ ProTaper NEXT ■ REVO-S ■ Twisted file ■ K3 XF ■ HyFlex CM ■ Reciprocation Instruments – WaveOne – Reciproc
- 4. ■ Self adjusting files ■ One shape single rotary file ■ One Curve ■ WaveOne Gold ■ Protaper Gold ■ Complications ■ Precautions while usng NiTi instruments ■ Price of rotary systems ■ Sterilization and Disinfection ■ Conclusion
- 5. Introduction ■ Endodontic instruments play a significant role in the success of endodontic treatment starting from the preparation of the access cavity to the final obturation of the root canal space. ■ A continuously tapering funnel shape with the smallest diameter at the end point and the largest at the orifice has been deemed to be the most appropriate canal shape for filling with gutta-percha and sealer. ■ Successful endodontic treatment relies upon endodontic instruments used for cleaning and shaping of the root canal system, which ultimately determines the clinical outcome. ■ Rotary systems have proved to be safer, quicker and more efficient over the conventional instruments
- 6. History of rotary instruments ■ 1800 - First Endodontic instrument- Barbed Broach by Edward Maynard ■ 1852-Arthur recommended the use of small files for Cleaning and shaping ■ 1885-TheGates Glidden drill were introduced. ■ 1889-William H. Rollins developed the first endodontic hand piece for automated root canal preparation (Specially designed needles 360 degree rotation and 100 R.P.M. ) ■ 1892-Oltramare – fine needles with rectangular cross section mounted in dental handpieces ■ 1915- K files ■ 1928-The Cursor Handpiece ■ 1962- Nickel titanium discovered byWilliam Beuhler and Frederick Wang ■ 1964- Giromatic Handpiece
- 7. Classification of Endodontic Instruments Based on Method of Use Group I: Hand-operated endodontic instruments – A. Barbed broaches and rasps – B. K-type reamers and files – C. Hedstroem files Group II: Low-speed instruments with latchtype attachments – A. Gates-Glidden drills – B. Peeso reamers Group III: Engine-driven instruments – A. Rotary NiTi endodontic instruments – B. Reciprocating instruments – C. Self-adjusting file (SAF) Group IV: Ultrasonic and sonic instruments
- 9. Gates-Glidden drills ■ long, thin shaft ending in a flame-shaped head, with a safe tip to guard against perforations. ■ The flame head cuts laterally and is used with gentle, apically directed pressure. ■ Uses: – Remove the lingual shoulder during access preparation of the anterior teeth – Enlarge root canal orifices ■ Recommended speed 750-1000 rpm Weakest part- safety design
- 10. Peeso reamers ■ long, sharp flutes connected to a thick shaft ■ Cuts laterally ■ Used for the preparation of post space when gutta-percha has to be removed from the obturated root canal.
- 11. Diameter of Slow-Speed Rotary Stainless Steel Instruments
- 12. Materials for manufacture of Endodontic Instruments Carbon steel • Rigidity increases with increased size • Less resistant to breakage by bending or twisting • The instruments are easily corroded • Low cost Stainless Steel • Greater flexibility than their carbon steel counterparts • Greater resistance to fracturing by twisting • Less sharper than Carbon steel • Resistant to corrosion NickelTitanium Alloys • Group of inter metallic alloys containing Nickel andTitanium • Discovered by Buehler in 1962 in the Space Program of the Naval Ordnance Laboratory, Maryland • Introduced into dentistry by Anderson in 1972 CRAIG, R.G., PEYTON, F.A.: Physical properties of stainless steel endodontic files and reamers. Oral Surg. 16:206, 1963
- 13. ■ In 1991, the first commercial nickel titanium manual and rotary files were introduced by NT Co. ■ in 1994, NT Co. also introduced the first series of nickel titanium rotary files having multiple non-conventional tapers: the McXIM Series, which had six graduating tapers ranging from the conventional 0.02 taper to a 0.05 taper file
- 14. ■ Austenitic NiTi (austenite): has a complex body-centered cubic structure, and exists at higher temperatures and lower stresses. ■ Martensitic NiTi (martensite) has a complex structure described as monoclinic, and exists at lower temperatures and higher stresses.
- 15. Shape Memory ■ Transformation between austenite and martensite occurs by a twinning process at the atomic level, and the reversibility of this twinning is the origin of shape memory Shape Setting: ■ To fix the original "parent shape," the alloy must be held in position and heated to about 500 °C (932 °F)
- 16. Superelasticity or Pseudoelasticity ■ elastic range 10–30 times greater than that of a normal spring material. ■ effect is only observed about 273-313 K (0-40 °C; 0-72 °F) above the Af temperature
- 17. Properties of NiTi "superelastic" or "austenitic" if Af is lower than a reference temperature "shape memory" or "martensitic" if higher. The reference temperature is usually defined as the room temperature or the human body temperature (37 °C; 98 °F).
- 18. Comparison of Properties of NiTi and Conventional Stainless Steel
- 20. Tip Design Cutting tip • Ability to enter narrow, calcified canals • Transportation • ProTaper Shaping files: partially active tips Non-cutting tip • Create concentric circle at the end of the root • ProFile, GreaterTaper (GT), K3, Hero 642, RaCe,Protaper Finishing files
- 21. Taper ■ instrumentation of a root canal by using files of the same taper but with varying apical tip diameters – A rotary file of constant taper would be the .04 taper Profile that has a constant taper (.04) but has varying apical tip diameters ■ instrumentation of root canal by varying or graduating tapers .These files have the constant apical tip size but their taper varies from .04 to .12. – Gradual increase in taper engaging a minimal aspect of the canal wall frictional resistance is reduced and requires less torque
- 22. GT Series-GT20, GT30 and GT40, according to ISO size Taper (10%, 8%, 6%, 4%) Quantec files RaCe - ISO 15-60 with various tapers of 2%, 4%, 6%, 8%, 10% Flex Master- ISO sizes 20, 25 and 30 - tapers (2%, 4% and 6%). ISO sizes 35 to 70 - 2% taper.
- 23. Differences between Shaping and Finishing file shapes
- 24. RakeAngle ■ angle formed by the cutting edge and a cross section taken perpendicular to the long axis of the instrument. ■ The cutting angle: angle formed by the cutting edge and a radius when the file is sectioned perpendicular to the cutting edge. ■ Positive rake angles: cut more efficiently ■ neutral rake angles: scrap the inside of the canal. ■ Most conventional endodontic files utilize a negative or “substantially neutral” rake angle. ■ Overly positive rake angle: digging and gouging of the dentin Separation. Negative Rake Angle: Profile Positive Rake Angle: K3, ProTaper, Hero 642, RaCe and Flex Master systems Neutral rake angle: Light Speed and GT
- 25. Radial Land ■ surface that projects axially from the central axis, between flutes, as far as the cutting edge. ■ Blade support is defined as the amount of material supporting the cutting blades of the instrument. ■ less blade support less resistant the instrument is to torsional or rotary stresses ProFile, GT Quantec K3 - three radial lands- peripheral mass- -prevents the propagation of cracks and -reduces the chances of separations and deformation from torsional stresses peripheral blade relief -reduced friction and control the depth of cut ProTaper, Hero 642, Endo Sequence and RaCe do not have radial lands.
- 26. Helical Angle ■ angle that the cutting edge makes with the long axis of the file ■ constant helical flute angle accumulation of debris, in the coronal part of the file ■ varying the flute angles debris will be removed in a more efficient manner the file will be less likely to screw into the canal
- 27. ■ K3 the helical angle increases from the tip to the handle – superior debris removal ■ RaCe file - “alternating helical design” – reduces rotational torque by using spiraled and non spiraled portions along the working length – reduces the tendency of the file to get “sucked into” the canal
- 28. Pitch ■ number of spirals or threads per unit length ■ K file has been designed with constant tapers, but with variable pitch and helical angles.The result is a dramatic reduction in the sense of being “sucked down into” the canal. ■ Profile has a constant pitch throughout its cutting shank. ■ The GT has variable helical angles and a variable pitch.Their variable pitched flutes provide a reamer like efficiency at the shank and K-file strength at the 21 tip . ■ ProTaper has continuously changing pitch and helical angle which reduces the screwing effect. RaCe features one set of cutting edges that alternates with a second set, pitched at a different angle
- 29. Generations of rotary systems
- 31. DESIGN FEATURES OF CURRENT ROTARY NITI FILE SYSTEMS
- 36. ProFile GT and GTX ■ GreaterTaper, or GT file : 1994. ■ U-file design and was marketed as ProFile GT. ■ increasing number of flutes in progression to the tip; ■ the apical instrument diameter was 0.2 mm. ■ Instrument tips were noncutting and rounded ■ these design principles also present in ProFile GTX, ■ use of M-Wire for GTX, changes in the longitudinal design, emphasized the use of the no. 20 .06 rotary ■ The GTX set currently includes tip sizes 20, 30, and 40, in tapers ranging from .04 to .010
- 37. LIGHTSPEED LSX ■ maximizes flexibility and allows larger apical preparations without unnecessary removal of dentin. ■ Non-cutting shaft and very short blade. ■ After making straight-line access to about midroot, the coronal third is flared with the instrument of choice (not with the LSX). After flaring, at least a #15 K-file is used to obtain patency to working length (WL). ■ A #20 LSX and sequentially larger sizes are used to prepare the apical third.The final apical instrument size (FAS) is the blade size that encounters 4mm or more of cutting resistance apically. A 4mm step back with the next larger (than the FAS) instrument completes the apical preparation. ■ The mid-root is then cleaned and tapered with the next two or three sequentially larger LSX sizes, blending mid-root instrumentation with the previously prepared coronal third. Recapitulation usually is necessary only once – with the FAS – at the end of canal preparation. ■ The new LSX is to be used at 2500 rpm, and irrigation is required throughout the procedure.
- 38. Protaper
- 39. ProTaper NEXT ■ fewer files when compared with the ProTaper Universal files ■ Variable taper ■ Rectangular off-center cross-section design for greater strength ■ Unique Asymmetric Rotary (AR) Motion : only two points of the rectangular cross section touch the canal wall at a time. ■ M-Wire NickelTitanium alloy for increased flexibility and resistance to cyclic fatigue as compared to traditional NiTi.
- 40. REVO-S ■ 3 instruments ■ snake like movement inside the canal ■ Works in a cyclic way- 3C concept – Cutting – Clearance – Cleaning ■ Rotational speed – 250- 400 rpm
- 43. Twisted file :2008 ■ First fluted NiTi file manufactured by plastic deformation ■ A size tip from #25 to #50 and in tapers from .04 to .12. ■ Unique features- – R-phase™ heat treatment technology – Twisting of the NiTi alloy instead of being ground – different surface texture (natural grain structure) that runs in the longitudinal direction – absence of transverse running machining marks slower crack initiation and propagation ■ R-phase technology: Employs a crystalline structural modification that maximizes flexibility and resistance to breakage
- 44. K3 XF: 2011
- 45. HyFlex CM ■ Coltene Whaledent HyFlex™ Controlled Memory NiTi Files ■ extremely flexible but without the shape memory ■ Allows pre-curving: reduces the risk of ledging, transportation or perforation ■ Regains shape after sterilization ■ 300 % more resistant to cyclical fatigue ■ Taper- 0.04,0.06 ■ Size - #15- #60 ■ Speed – 500 rpm ■ Torque – 2 N.cm
- 46. Reciprocating instruments ■ Function at unequal bidirectional angles. ■ CCW engaging angle is 5x the CW disengaging angle ■ After 3 CCW and CW cutting cycles, fill will have rotated 360o ■ Eg.WaveOne system and Reciproc
- 47. WaveOne ■ Only 1 file is generally utilized to fully shape virtually any given canal ■ 3WaveOne files available – WaveOne Small file: is used in fine canals.The tip size is ISO 21 with a continuous taper of 6%. – WaveOne Primary file: is used in the majority of canals.The tip size is ISO 25 with an apical taper of 8% that reduces towards the coronal end – WaveOne Large file: is used in large canals. The tip size is ISO 40 with an apical taper of 8% that reduces towards the coronal end.
- 48. ■ changing pitch and helical angle ■ 2 distinct cross-sections along the length of their active portions. ■ From D1-D8: modified convex triangular cross- section ■ D9-D16: convex triangular cross-section ■ Noncutting modified guiding tips
- 49. Reciproc ■ R25- 8% taper, R40- 6% taper, R50- 5% taper ■ M-wire NiTi. ■ non-cutting tips. ■ S shaped cross- section. ■ used at 10 cycles of reciprocation per second. ■ When the instrument rotates in the cutting direction it will advance in the canal and engage dentine to cut it.When it rotates in the opposite direction (smaller rotation) the instrument will be immediately disengaged. ■ associated with a significantly higher cyclic fatigue resistance than the WaveOne instruments.
- 50. File Selection
- 51. Self adjusting file ■ single instrument type, namely the SAF, introduced by Zvi Metzger ■ three dimensionally adapts both longitudinally and along the cross-section of the root canal system ■ uniform cutting action of the dentin from the canal walls (60– 75 μm thick) ■ hollow compressible NiTi lattice with a thin-walled pointed cylinder 1.5 or 2.0 mm in diameter ■ continuous irrigation by a silicon tube ■ in-and-out manual motion using two cycles of 2 minutes each for a total of 4 min/canal ■ increased flexibility as it lacks a metal core ■ less susceptible to fracture
- 52. One Shape Single Rotary File ■ Variable cross-section in one file. ■ Minimum radial contact to ensure better cutting. ■ The variable pitch enable efficient debris transport and reduces the screwing effect. ■ Superior ability to negotiate curve canals. ■ Torque: 2.6 N Speed: 350 RPM ■ 3 different cross-section zones – The first zone presents a variable 3-cutting edge design. – The second, prior to the transition, has a cross-section that progressively changes from 3 to 2 cutting edges. – The last (coronal) is provided with 2 cutting edges
- 54. The Endo DNA ■ heat-treated Nickel-Titanium alloy, ■ single-use rotary file ■ enables shaping of the full length of the canal with a single instrument, directly to the apex. ■ direct downward movement to the working length ■ Controlled memory • Pre-bendable • Conservation of the curvature ■ Speed 300 rpm ■ Torque 2.5 N.cm ■ L 21, 25, 31 mm
- 55. WaveOne Gold ■ Single-use file system ■ 4 files are termed Small (yellow 20/07), Primary (red 25/07), Medium (green 35/06), and Large (white 45/05) ■ fixed taper from D1-D3, yet a progressively decreasing percentage tapered design from D4- D16, which serves to preserve dentin ■ alternating offset parallelogram-shaped cross-section- two 85o cutting edges ■ Cyclic fatigue resistance higher thanWaveOne Primary and Reciproc single-file systems
- 57. ProTaper Gold ■ Progressively changing helical angle and pitch ■ 11 mm handle
- 59. Complications ■ Torsional fatigue ■ Flexural fatigue ■ Factors responsible – Operator – Root canal morphology – Instrument geometry Fracture
- 60. Nickel–Titanium Precautions and Prevention ■ Never force a file! Passive technique ■ Canals that join abruptly at sharp angles:The straighter of the two canals should first be enlarged to working length and then the other canal, only to where they join ■ Do not overuse ■ Curved and calcified canals ■ Not to be used to bypass ledges. ■ ‘S’-type curves: Adequate flaring of the coronal third to half of the canal
- 61. ■ debris pattern: on the middle portion of the file ■ files ‘locking up’: rotate the instrument in a counterclockwise direction and remove it from the canal. ■ file feels tight throughout the length of blade: orifice andcoronal one- third to two-thirds of the canal need increased taper. ■ tip should not be used to drill into the canal ■ any bend on used file: instrument is fatigued and should be replaced ■ Length of file: maybe inaccurate, if unraveled or twisted
- 65. Disinfection and Sterilization ■ Autoclave ■ Chemiclave ■ Glass bead/Salt sterilizer ■ Plasma Sterilizer ■ Dry heat ■ Ethylene Oxide ■ Alcohol Methods ■ Lasers ■ Ultrasonic cleaning ■ Chlorhexidine ■ Hypochlorite ■ Quaternary ammonium compounds ■ Hydrogen peroxide ■ Sodium dodecyl Sulphate
- 67. Conclusion ■ The tool are only as good as the man who wields them ■ Much of what is known about NITI-shaping instruments has been learned in clinical practice on patient’s record. ■ Rotary instruments are here to stay, they will continue to improve , but they are not a panacea. ■ However they are an important adjunct for canal shaping procedures
- 68. References ■ Ingle’s Endodontics: 6th Edition Chapter 25 and 26 ■ Grossman’s Endodontic Practice. 13th edition ■ ZARNA SANGHVI et. al. : Rotary Instruments in Endodontics.The Journal of Ahmedabad Dental College and Hospital; 2(1), March 2011 - August 2011 ■ Singh K, Bindra SS, Singh G, Kaur H. Endodontic rotary systems - A Review. J Adv Med Dent Scie Res 2016;4(4):62-66. ■ Ove A. Peters, DMD, MS, PhD1/Frank Paqué, Dr Med Dent . Current developments in rotary root canal instrument technology and clinical use: A review. Quintessence Int 2010;41:479–488