Rotary endodontics

1. MDDr.Radovan Žižka Rotaryendodontics

2. Aimofseminary • Basic informationabout Ni-Ti alloy • DividingNiTirotaryinstruments • Tip configuration • Cross-sectional design • Flute design • Rakeangle • Taper • Principles o NiTiinstruments • FracturepreventionofNiTiinstruments • TechniquesusedwithNiTifiles

3. NiTialloy • 1963 – developedforspace program by Buehlerat Naval Ordonance Laboratory in SilverSprings, Maryland, USA • Verylowelasticmodulus (permitnegotiationofcurvedcanals) • Superelasticbehavior • Shapememory

4. Tip configuration • Cutting • Transportationofcanal in lessexperiencedhands • Makingapicalsealandobturationdifficult • Goinglongwithit, createsanellipticaltearattheendoftheroot • Non cutting • Reducesthe risk ofledging,scratchingorgouging • Makingapicalsealandobturationeasier • Goinglongwithit, createsconcentriccircleattheendoftheroot

5. Crosssectional design • Triangular • Square • U shape • S type • Convex triangle • Proprietaryones

6. Flute design part 1 • Landedflute design(withradiallands) • Cuttingedges had beenflattened (namedradiallands), U-file design • Instruments have to bepushedwithlightpressure to engagetheperimeterofthecanalandthencutthe dentin there • Makepreparationslowerbutsafer • Increasestrenghtanddecrease flexibility • Goodcenteringof instrument, preventingbindingorscrewing to dentin Radialland U shape

7. Flute design part 2 • Non-landedflute design • Sharp cuttingedgesresultingfrom a traingularcrosssectional design thatcuts more rapidlybutcanleadalso to preparationerrors • Consider more efficientbutrequire more operatorskill to avoidproceduralmishapcompared to radial-landedfiles • More flexible • Others Sharp cuttingedge

8. Rakeangle Istheangleformed by thecuttingedgeand a crosssectiontakenperpendicular to thelong axis ofthe instrument • Possitiverakeangle • Shave dentin • Negative rakeangle • Scrape dentin • Neutralrakeangle • Plan dentin

9. PrinciplesofNiTi part 1 • Not use as pathfinder • Should not beused to negotiatesmallcalcifiedcanalsorcurvedcanalsbecauseofits non cutting tip • Should not beused to bypass ledges • Should not beappliedwithpressure • Should not beusedforestimatingworkinglenght (stainlesssteelinstruments are more opaque)

10. PrinciplesofNiTi part 2 • Need more flaringofaccess to decreasefatigueoffile • Mustbeused in a lubricatedcanal to reducefrictionalresistance • Should not beused in abruptcurves, S-shapesandcanalsthatjoin • Oncethe instrument starts to wobble in thehandpiece, thefileshouldbedisposedoff

11. PrinciplesofNiTi part 3 • WhenNiTiexperiencesanyundue stress includingcyclicfatigue, the metal undergoes a crystalline (microscopic) phasetransformationandbecomestructurallyweaker • Cuttingefficiencydecreaseswithrepeatedsterilization(prone to fracture) • NiTifilemaydisarticulatewithoutanywarningespeciallyif not properlyused • Each instrument should not beused more than 5-10 secundsonly

12. FracturepreventionofNiTirotaryinstruments part 1 • Use onlytorquecontrolledhandpiece • Establishingof proper glidepath • Use ofcrown-downtechnique • Frequentcleaningofflutes • Do not forcethefileapicallyagainstresistance • Removethe maximum possible pulp tissuewithbroachbeforeusingrotaryfiles

13. FracturepreventionofNiTirotaryinstruments part 2 • Canalsshouldbewelllubricated (no dentin mudwhichincreasethe risk offracture) • Discardthefileifitisbent, stretched, has shinyspotsorwobbles in handpiece • Do not use rotaryfiles to trueworkinglenghtespecially in teethwith S-shapedcanals, sharpcurves • Frequentlyinspectfileflutesundermagnification

14. Typesofrotaryinstrumentsaccording to tapering • Tapered • Constant - thediameterincreases in a constantmanner (Profile) • Progressive - thediameterincreases in a progressivemanner (ProTaper) • Variable - whetherincreaes in a variablemanner (S1,S2) orincreasesthendecrease (SX, finishingfiles) • Non-tapered

15. Techniquesthatmightbeusedforrotaryinstrumentation • Crown-downpressurelessmethod • Modifiedcrowndownmethod • Graduatingtapermethod • Startingwithsmallertaperedinstruments, whereeach instrument istaken to thefullworkinglenghtandthenproceedingwithlargertapers (tip sizeisconstant) • Step-backmethod • Modified step-backmethod • Use ofLightspeedsystem

16. ProTaper • IsoneofwidelyusedNiTisystemtoday • InnovationswhichcharacterizeProTaper: • Progressive/variabletaper • Modifiedguiding tip(rounded, non-cuttingandparabolicshaped tip) • Varying tip diameters • Convextriangularcross-section (not allofthem) • A positive rakeangle • Shorter handle ofthefile • Worklonger in superelasticphacethan do instrumentswith U-file design

17. ProTaperinstruments • 3 shapingand 3 finishingfiles (and 2 additionalfinishingfiles) • Shaping • SX,S1,S2 • Finishing • F1,F2,F3 • F4,F5 http://www.dentsply.com

18. ProTaper SX • SX File (auxiliaryshapingfile) • Tip size – ISO19 • Taper -D0-D9 – from ISO 19-ISO 100 -D9-D14 – from ISO100-ISO120 (reduction in taper to increase flexibility) • Colorcode – none • Designed to • Coronalflaring • Relocatethecanalawayfromtheexternalrootconcavities http://www.dentsply.com

19. ProTaper S1 • S1 File • Tip size – ISO18,5 • Taper - D0-D14 – from ISO 18,5-ISO 120 (Increasiblylargertaper) • Colorcode – purple • Designed to • Preparationcoronal 1/3 ofrootcanal http://www.dentsply.com

20. ProTaper S2 • S2 File • Tip size – ISO20 • Taper - D0-D14 – from ISO 20-ISO 110 (Increasiblylargertaper) • Colorcode – white • Designed to • Enlargeandpreparethemiddle 1/3 in addition to thecriticalcoronal region oftheapical 1/3 http://www.dentsply.com

21. ProTaper F1 • F1 File • Tip size – ISO20 • Taper - D0-D3 – 7° taper - D3-D14 – a reduction in taper to increase flexibility • Colorcode – yellow • Designed to • Primarily to finishapical 1/3 ofthecanal • Expandthemiddle 1/3 ofthecanal • Plane awaythevariations in canaldiameteraftershaping http://www.dentsply.com

22. ProTaper F2 • F2 File • Tip size – ISO25 • Taper - D0-D3 – 8° taper - D3-D14 – a reduction in taper to increase flexibility • Colorcode – red • Designed to • Primarily to finishapical 1/3 ofthecanal • Expandthemiddle 1/3 ofthecanal • Plane awaythevariations in canaldiameteraftershaping http://www.dentsply.com

23. ProTaper F3 • F3 File • Tip size – ISO30 • Taper - D0-D3 – 9° taper - D3-D14 – a reduction in taper to increase flexibility • Colorcode – blue • Reducedcross-sectionwith U-file design • Designed to • Same as F1 and F2 • Rigidandagressive http://www.dentsply.com

24. ProTaper • In additionthere are F4 (double black, ISO40, initialtaperis 6°) and F5 (double yellow, ISO50,initialtaperis 5°) • Shapinginstrumentsshouldbeused in brushingmotion, finishingwith just lightpressure • Aftereach instrument irrigation,establishingpatencyandreirrigation

25. ProTapertechnique • Scout coronal 2/3 with K-file ISO 10, ISO 15 (coronalglidepath) • Shapingcoronal 2/3 with S1,S2 • Scout apical 1/3 with K-file ISO 10, ISO 15 – establishingworkinglenght (apicalglidepath) • Finishingapical 1/3 with S1,S2,F1….

26. http://www.dentsply.com

27. AdvantagesofProTaper part 1 • Patentedprogressivetaper design • Fewerfiles are needed to achievefullytaperedcanal • Convextriangularsection • Increasethecuttingefficiency • Increasetactilesensation • Decreasethelateralcontact area betweenfileand dentin • Decreasetorsionalload, filefatigue and breakage

28. AdvantagesofProTaper part 2 • Themodifiedguiding tip caneasilyfollow a preparedglidepath • A progressivelychanginghelicalanglesandbalancedpitches • Stabilizingeach instrument • Aiding in debrisremoval • Effectivelyreducingthreading (screwing, grabbingandtaperlock)

29. ProTaperNext http://www.dentsply.com