biomechanical instrumentation

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Biomechanical Instrumentation

Rotary Canal PreparationDr. Ebtissam Al-Madi1Al-Madi, 491 DenOutlineObjectives of Cleaning & ShapingBiologicalClinicalMechanicalInstrumentation TechniquesStepback techniqueCrowndown techniqueRotary Instrumentation2Al-Madi, 491 DenBiological Objectives Removal of all tissue, bacteria and bacterial products and substrates from the root canal system MechanicalShaping of the root canal system to facilitate placement of a root canal fillingClinicalEliminate apical periodontitis and return tooth to normal function

3Al-Madi, 491 DenCleaningShapingFillingEndodontic TriadShaping to facilitate cleaning and Filling4Al-Madi, 491 DenAccess PreparationCleaning & Shaping of the canalObturation Restoration5Al-Madi, 491 DenStepback6Al-Madi, 491 DenStepback Technique (1960s)The most widely used preparation technique Replaced Non-tapering Preparation technique

7Al-Madi, 491 DenStepback TechniqueApical Preparation:Establish access (straight line)Establish working lengthFile Instrument (watch-winding, file, ream, etc)Place next larger file, instrument, and repeat till you reach file 3-4 sizes larger (MAF)

8Al-Madi, 491 DenStepback TechniqueStep back:Place next larger file to a length 1 mm shorter of working length, file, irrigate and recapitulateRepeat process with successively larger files at 1 mm increments shorter than preceding file.

9Al-Madi, 491 DenStepback TechniqueVariations to the classic stepback techniqueInitially enlarge coronal aspect with GG burs Complete coronal preparation with GG bursUse of small GG burs in mid-root levelUse of Hedstrom files to flare the preparation10Al-Madi, 491 DenStepback techniqueAdvantagesMinimize procedural errors (transportation, ledging, apical perforation)DisadvantagesSignificant apical extrusion of debris (post-operative pain)Apical blockageCanal deviationAlteration of working length11Al-Madi, 491 DenCrown down12Al-Madi, 491 DenCrowndown TechniqueMore recent techniqueProduce similar result to step-back13Al-Madi, 491 DenCrowndown techniqueDevelopment of straight-line accessEliminate pulp chamber obstructions and check patencyGG enlargement with size 4-3-2, irrigateCoronal to mid root enlargement with instruments from large to small, irrigateEstablish working length, irrigateIntroduce progressively smaller files deeper into the canal until resistance is encounteredEstablish apical preparation sizeComplete preparation

14Al-Madi, 491 DenCrowndown techniqueVariations to the classic crowndown techniqueCrown-down pressure-less techniqueRoane techniqueDouble flare techniqueModified double flare techniqueRotary Instrumentation15Al-Madi, 491 DenCrowndown techniqueAdvantagesReduce apical extrusion (reduce pain)Elimination coronal interferencesImproved irrigation to apical part of canal Facilitate working length determinationDisadvantagesEarly blockage of canal

16Al-Madi, 491 DenInstrumentsHand InstrumentsRotary Instruments

17Al-Madi, 491 DenHand instrumentsBeen in use for over 100 yearsStill integral part of cleaning & shapingBetter tactile sensationISO standardizationBroaches, k-files, Flex-R files, NiTi files, H-files

18Al-Madi, 491 DenHand engine drivenProperties of NiTi AlloySuperelasticityHigh resistance to cyclic fatigueSeries 29

19Al-Madi, 491 DenRotary FilesAdvantagesLess transportation and ledgingShape canal uniformlyReduced operator fatigueImproved efficiency

DisadvantagesCannot be used in some casesBuildup of debrisCannot use beyond apical foramenFracture can occur suddenlyInitial costLoss of tactile sensation20Al-Madi, 491 DenRotary InstrumentsLightspeedProfileHeroQuantecK3FlexmasterGT

ProtaperSequenceRaCeV-taper21Al-Madi, 491 DenDesign characteristicsNon-cutting vs cutting tipTip sizeTaperCross sectionRake angleHelix anglePitch22Al-Madi, 491 Den

Tip could be non-cutting, cutting

Tip shape23Al-Madi, 491 DenTip Size

Can be the same as ISO hand tips sizes- color coded accordingly Can be half sizes (12.5, 17.5, etc) as in Light Speed. Can skip sizes ( only 20,30, 40) as in GT rotary Can be nonspecific sizes (according to percentages ex. 18.5, 20..) as in ProTaper.24Al-Madi, 491 Den

Taper ranges from 0.02 to 0.12Tip Taper25Al-Madi, 491 DenConstant taper- Variable tipHand files (0.02)Profile 0.04Graduating taper- constant tip sizeGT seriesQuantecVarying taper- different tip sizesProTaperTip Taper

26Al-Madi, 491 DenCross section- Radial LandsA radial land is a surface that projects axially from the central axis, between flutes, as far as the cutting edge

Non-cutting tips and radial lands keeps a file centered in the canal.

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Increased radial land increases peripheral strength behind the cutting blade

Smaller radial land equals decreased strength for blade support Cross section- Radial Lands28Al-Madi, 491 DenRake AngleThe rake angle is the angle formed by the cutting edge and a cross section taken perpendicular to the long axis of the instrument

Rake angles affect the cutting efficiency and the aggressiveness of the file29Al-Madi, 491 Den

Overly Positive Rake Angle

Positive Rake Angle

Neutral Rake Angle

Negative Rake Angle Rake Angle30Al-Madi, 491 DenAs the flute angle is increased more debris can be carried away from canal.

Helical flute anglesThe helical angle is the angle that the cutting edge makes with the long axis of the file

Constant helical flute angles allow debris to accumulate and are more susceptible to the effect of screwing in forces.31Al-Madi, 491 Den

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33Al-Madi, 491 DenPitchPitch is the number of spirals or threads per unit length.

Constant pitch and constant helical angles produce a pulling or sucking down into the canal.34Al-Madi, 491 Den35Al-Madi, 491 DenLightspeed (Senia & Wildey 1990s)Long, thin non-cutting shaftU shape designMost flexible RILow incidence of transportation, preparation errors, and loss of working length

36Al-Madi, 491 DenCoronally pre-enlargeGauge apical canal diameter (FLSB)Insert instrument with a slow continuous apical movement and then pecking motions12 peck rule (MAR)One size larger 4mm shorter and instrument with 3-4 LSRecapitulate to WL with MAR

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Lightspeed38Al-Madi, 491 DenProfile (Ben Johnson 1994)Increased taperBegan as series 29 #0.02 taper, then #0.04 and 0.06 tapersProfile (maillefer-Europe) manufactured tips similar to ISONegative rake angle

39Al-Madi, 491 DenCoronally pre-enlargeUse of Orifice shapersAlternative use of #.04 and #.06 tapers as well as alternate tip sizesSame basic technique for similarly designed files

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Profile41Al-Madi, 491 DenProfile42Al-Madi, 491 DenGT Files ( Steve Buchanan 1994)U-file designStandard GT filesAccessory GT FilesProfile .04

43Al-Madi, 491 DenGT rotary

44Al-Madi, 491 DenQuantec10 filesHas different tapersSlight positive rake angle

45Al-Madi, 491 DenHERO 642(High Elasticity in Rotation)2nd generation instrument with +ve rake angle

46Al-Madi, 491 DenK3 (McSpadden)Predecessors:Quantec Unique cross sectional design with +ve rake angle, 3 wide radial lands, peripheral blade relief

47Al-Madi, 491 DenK348Al-Madi, 491 DenFlexmasterTriangular cross section with no radial landsHigh manufacturing quality

49Al-Madi, 491 DenProTaper(Cliff Ruddle, John West, Pierre Matchou)Only 6 instrumentsModified k file with no radial landsVarying taper that increase coronally in shaping files and opposite in finishing files

50Al-Madi, 491 DenProtaperEasier techniqueLess instruments, and changing2 files due the job of shaping, and 1 of 3 does the job of finishing

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ProTaper52Al-Madi, 491 DenProTaper53Al-Madi, 491 DenRaCe(Reamer with alternating cutting edges)Twisted areas alternating with straight areasReduced tendency to screw in canal

54Al-Madi, 491 DenV taper fileSuperiorly ground using CAD-CAM technologyVariable taper that follows natural taper of canal

55Al-Madi, 491 DenHybrid techniqueInstruments can be used in a manner that promotes their individual strengths and avoids their weaknessesHand instruments secure a patent glide pathTapered rotary instruments efficiently enlarge coronal canal areasLess tapered instruments allow additional apical enlargement56Al-Madi, 491 DenNewer Rotary Instruments?Light SpeedHero 642GT filesQuantecFlexmaster

RaCeV-TaperEndo Sequence57Al-Madi, 491 DenMore informationPathways of the Pulp 9th e-editionEndodontics- Ingle 5th CD editonAdvanced Endodontics- RhodesEndodontics- StockJOEIEJCompany brochures & VideosInternet

58Al-Madi, 491 DenHow & Where to learn?Read & understand the brochure- Don't be fooled!Read the literature in textbooks and journals- Be an informed consumer.Try on extracted teeth till you master the technique- try before you buy.

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