4. Biomechanical Preparation ..........ppt

biomechanical preparation , techniques

1. Preparation of radicularspace
instruments and technique
BY-DR ANURAG JAIN

2. CONTENTS
Introduction
Definitions
Classification
History
Objectives
Rules for cleaning and shaping
Motions of cleaning and shaping
Techniques of cleaning and shaping
Conclusion
Refrences

3. INTRODUCTION
Biomechanicalpreparationreferstothecontrolled
removalofdentinandrootcanalcontentsby
manipulationofrootcanalinstrumentsand
materials.
Itconsistsofcleaningandshaping.

4. DEFINITIONS
Shaping & Cleaning
Shaping and cleaning of root canal
consist of removing the pulp tissue and
debris from the canal and shaping the
canal to receive an obturating material.

5. Shaping
Shapingisdonetoremoveallthecontentsfrom
therootcanalsystem,toworkdeepinsidethe
canal,andtocreateasmooth,taperedopeningto
theterminusforthree-dimensionalobturation.

6. Schildergave
5 mechanical objectives
1.Therootcanalpreparation
shoulddevelopacontinuously
taperingconicalform.
2.Makethepreparationin
multipleplanes
3.Makethecanalnarrower
apicallyandwidestcoronally.
4.Avoidtransportationofthe
foramen.
5.Keeptheapicalforamenas
smallaspossible.

7. Biologic objectives
Biologic objectives are to remove the pulp tissue, bacteria and
their by-products from the root canal space.
Procedureshouldconfinedtotherootcanalspace.
Necroticdebrisshouldnotbeforcedbeyondtheforamen
duringcanalpreparation
Removealltissuedebrisfromtherootcanalsystem
Createsufficientspacetoreceiveintracanalmedicament

8. GROSSMAN’S RULES
1.Directaccessshouldbeobtainedalongastraightline.
2.Workinglengthshouldbeaccuratelydetermined.
3.Useoftheinstrumentsinsequentialorderwithperiodic
recapitulation.
4.Instrumentsshouldbeusedwithquartertohalfturnand
withdrawnwithapullstroke.
5..Barbedbroaches-shouldbeusedonlywhenthecanalis
wideenoughtopermittheirInsertion&rotationwithout
binding.

9. 6..Instrumentsshouldbefittedwithinstrumentstops.
7.Apical(3to4mm)shouldbeenlarged3sizesgreaterthaninitialapicalfile.
8..Neverforceaninstrumentifitbinds.
9.Instrumentsshouldbecheckedfordeformation&discardedifstrained.
10.Instrumentationshouldbedoneusingsterileinstrumentsinawetcanal.
11.Debrisshouldnotbeforcedthroughtheapicalforamen
12.Instrumentsshouldbeconfinedtotherootcanalspacetopreventperiapical
trauma.
13.Precurvethefilebladebeforeinstrumentation.

10. Ingle and levine’s
standardization
Instruments shall be numbered from 10 to 100; the
numbers to advance by 5 units to size 60 and then
by 10 units to size 100. This has been revised to
include numbers from 6 to 140.
Each number shall be representative of the diameter
of the instrument in hundredths of a millimeter
at the tip; e.g., No. 10 is 10/100 or 0.1 mm at the
tip, No. 25 is 25/100 or 0.25 mm at the tip, and No.
90 is 90/100 or 0.9 mm at the tip.
The working blade (flutes) shall begin at the
tip, designated site D0, and shall extend exactly
16 mm up the shaft, terminating at designated
site D16.

11. The diameter of D16 shall be 32/100 or 0.32 mm
greater than that of D0; e.g., a No. 20 reamer
shall have a diameter of 0.20 mm at D0 and a
diameter of 0.20 plus 0.32 or 0.52 mm at D16.
This sizing ensures a constant increase in taper
of 0.02 mm/mm for every instrument regardless
of size.
Following specifications were added later:
The tip angle of an instrument should be 75 ±15°.
Instrument sizes should increase by 0.05 mm at D0,
between Nos. 10 and 60, e.g., Nos. 10, 15, and 20,
and they should increase by 0.1 mm from Nos. 60
to 150, e.g., Nos. 60, 70, and 80.
Nos. 6 and 8 have been added for increased instrument
selection.
In addition, instrument handles have been color
coded for easier recognition

12. Fig : Specifications for an endodontic instrument. D0, diameter at the tip, in
hundredths of millimeters; D16,
diameter
in hundredths of millimeters at the end of the cutting blade, i.e., 16 mm
from D0. The taper of the instrument
from D0 to D16 is in increments of 0.02 mm in width per millimeter of length.
The tip angle of the instrument
should be 75 ±15°.

13. Specification of files and reamers

14. Classification of endodontic
instruments based on method of
use
yyGroup I: Hand-operated endodontic instruments
A. Barbed broaches and rasps
B. K-type reamers and files
C. Hedstroem files
yyGroup II: Low-speed instruments with latchtype
attachments
A. Gates-Glidden drills
B. Peeso reamers
yyGroup III: Engine-driven instruments
A. Rotary NiTi endodontic instruments
B. Reciprocating instruments
C. Self-adjusting file (SAF)
yyGroup IV: Ultrasonic and sonic instruments

15. a. Barbed Broaches and RaspsBroaches
and
rasps were the earliest endodontic instruments
used
to extirpate the pulp and enlarge the canal. A
barbed
broach is a short-handled endodontic instrument
often used for the extirpation of the entire pulp
and for the removal of necrotic debris, absorbent
points, cotton pledgets, and other foreign
materials
from the root canal.

16. K-type Files
the efficiency of root canal preparation In the early
1900s,Kerr Manufacturing Company designed and
manufactured new K-type endodontic instruments to
improve efficacy of root canal .

17. K type reamer
The traditional reamer, manufactured from
a
triangular blank, and file, manufactured
from a
square blank

18. Clinical Note
ŠŠClinically, files and reamers are recommended to be
used in a penetration, rotation, and retraction motion.
ŠŠFiles can also be employed in a filing or a rasping
motion once canal patency is achieved.
ŠŠHeuerreported that files are manufactured from
blanks twisted to produce tighter flutes, and reamers
are manufactured with looser flutes.
ŠŠAs the use of square blanks results in instruments
that resist fracture more effectively than those made
from triangular blanks, square blanks are generally
used for smaller, fragile instruments.
,

19. Hedstromefiles
Hedstroemfiles, also known
H-files, are manufactured from a round
stainless steel wire machined to produce
spiral flutes resemblingcones or a screw.
This instrument has a higher cutting
efficiency than K-instruments, but it is fragile
and fractures easily

20. Gates-Glidden Drills
•The Gates-Glidden drill has a 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.
•The long shaft is designed to break at the neck,
the narrowest diameter that lies adjacent to the
handpiece.
•If the drill binds during use, it will fracture at the
neck of the shaft and will extrude from the tooth.
•The fractured segment is easily removed by
grasping
the broken shaft with pliers and pulling it out of

21. The Gates-Glidden drill is used to:
•ŠŠ Remove the lingual shoulder during access
preparation of the anterior teeth
•ŠŠ Enlarge root canal orifices

23. Peesoreamer
The Peeso reamer has long,sharp flutes
connected to a thick shaft .
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.

24. Fig:Barbed broach used for extirpation of the
pulp and gross debridement of the root canal
Endodontic instruments used for cleaning
and shaping the root canal: (a) K-file, traditionally
made from a square blank. (b) K-reamer, traditionally
made from a triangular blank. (c) Hedstroem file,
machined from a round blank to produce spiral flutes

25. PHASES IN SHAPING OF ROOT
CANAL
yyPhase I: Negotiating the canal—“patency
filing”
yyPhase II: Coronal pre-enlargement
(recommended
for certain shaping techniques)
yyPhase III: Working length measurement
yyPhase IV: Root canal shaping techniques
yyPhase V: Root canal working width

26. FIG:Patency filing: (a) Radiograph (schematic
view) is studied for anatomical variations and size of
the image of the root canal. (b) and (c) A size 10 K-file
is precurved and introduced into the canal passively just
through the apical foramen. (d) The root canal is copiously
irrigated with a 5% solution of sodium hypochlorite
to remove loose debris and blood.

27. ANATOMICAL
CONSIDERATION

28. METHODS OF DETERMINING WORKING LENGTH
I. Radiographic methods
yyIngle’s technique (Recommended)
yyOthers
––Best’s method
––Bregman’s method
––Bramante’s technique
––Grossman’s method
––Weine’s method
yyKuttler’s method
yyX-ray grid method
yyXeroradiography
yyDirect digital radiography
II. Electronic apex locators
III. Nonradiographic methods (not recommended)
yyTactile sense
yyApical periodontal sensitivity
yyPaper point method

30. Different Movements of Instruments
Filing
Reaming
Combinationofreamingandfiling
Watch-Winding
Watch-windingandpull
Balancedforcemotion

31. Filing–Itissimplyanin–and–outmotionofthefilewith
amplitudeof2-3mm.Theinstrumentisplacedintothecanal
,pressureisexertedagainstthecanalwall,andinstrumentis
withdrawnwithoutturning.Thepressureismaintained
throughouttheprocedure.

32. Reaming–Itisacontinuousclockwiserotationofthe
instrument.Reamingproducesaroundtaperedpeparation.

33. Combinedreamandfilemotion–Thefileisinsertedwitha
quarterturnclockwiserotation,andaninwarddirectedhand
pressure(reaming)positionedintothecanalbytheactionofthe
file,andissubsequentlywithdrawnasacuttingmotion
(filling).Therotationduringplacementsetsthecuttingedgesof
thefileintothedentin,andnonrotatingwithdrawlbreaksloose
thedentinthathasbeenengaged.

34. CIRCUMFERENTIAL FILING
It is similar to filing motion but can be
used in large diameter canals .
The file is inserted in the root canal till
apex, laterally pressed against one side of
the canal wall and withdrawn with pulling
motion, to file the dentinal wall.
This procedure is repeated
circumferentially around all walls of the
canal.

35. Watchwinding–Itisabackandforthmovementofthefile
whileitisgentlybeingadvancedapically.Theamplitudeofthemotion
inastraightcanalis30-60degreerightandleftfromthecentrepoint,
withacurvedcanaltherotationmaybeonlyafewdegreesineach
direction.Itismuchlikethefilehandleisbeingrolledbackandforth
betweenthethumbandforefingerwhileaslightapicalpressureis
applied.

36. Watchwindingandpull–
.This is primarily used with H file.
The file inserted with right and left back and forth
motion until it meet resistance then it is taken out of the
canal by pull stroke.

37. BALANCED FORCE TECHNIQUE
RoaneandSabalagavethebalancedforce
technique.
ItemploysnewKtypefiledesignsknownas
Flex-RfilesandFlexofile.
Insertionisdonebyaquarterturnclockwise
rotationwhileslightornoapicalpressureis
applied.
Cuttingisthenaccomplishedby
counterclockwiserotation(180°–270°)
applyingsufficientapicalpressuretothe
instrument.
Theprocessisrepeatedseveraltimestill
workinglengthisreached.
Thefileisthenremovedfromthecanalbya
slowclockwiserotation.

38. ANTICURVATURE FILING
ThismotionwasdescribedbyAbouRass,
GlickandFrank.
Itpreventsexcessiveremovalofdentinfrom
thinnerrootsectionsincurvedcanals.
Theunderlyingobservationwasthatthe
furcationside(dangerzone)ofcrosssection
ofmesialrootofmandibularmolarshasless
dentinthicknessthanmesialside.(saftey
zone).
Itincludeduseofprecurvedfilesthatwere
manipulatedtofilethecanalawayfrom
dangerzone.

39. Thereare6motionsofFilesandreamers.
1.Follow
Usuallyperformedwithfiles.
Initiallyusedduringcleaningandshaping,oranytimean
obstructionblockstheforamen.
Precurvingallthewaytothetipoftheinstrumentisthepart
offollow.
2.Follow-withdraw–
Thismotionisusedwhentheforamenisreached,andthe
nextstepistocreatethepathfromaccesscavitytoforamen.
Thismotionisfollowandthenwithdraw.Itis,simply,anin-
and-out,passivemotionthatmakesnoattempttoshapethe
canal.

40. 3.Cart –
Cartingreferstotheextensionofareamertoornearthe
radiographicterminal.
Theprecurvedreamershouldgentlyandrandomlytouchthe
dentinalwallsatradiographicconstrictionand"cart"away
dentinaldebrisandpulpremnants.
4. Carve-
It is done for shaping the canal.
Reamers are the best instruments for carving.
Never press the reamer apically .
Simply touch the dentin with a precurved reamer and shape on
withdrawal.

41. 5.Smooth-
Smoothingisusuallydonewithfiles.
circumferentialfilingmotionisused.
6.Patency–
Patencyisachievedwithfilesorreamers.
Itmeanssimplythattheportalofexithasbeenclearedofany
debrisinitspath.

43. Techniques for
preparing root canals:

44. Techniques for preparing root canals:
Apical coronal technique
Coronal-apical technique
In which the WL is established and the
full length of the canal is then prepared.
In which the coronal portion of the
canal is prepared before determining
the WL

45. APICAL-CORONAL PREPARATION
Disadvantages
Apical plug
Decreased volume of
irrigating solution
Procedural mishaps
Advantages :
Conservation of tooth
structure especially in
cervical third

46. CORONO APICAL PREPARATION
ADVANTAGES
Bettertactileawarenessin
negotiatingthedelicateapical
thirdmicroanatomy.
Itreducespressure
Holdsgreatervolumeofirrigant
-enhancescleaning.
Removalofdentinmud
decreasesposttreatment
problems
Improvesidentifyingtheforamen
DISADVANTAGES:
Increased removal of
tooth structure

47. Standardized preparation/ Single –length technique
The standardized technique uses the same WL for all
instruments introduced into a canal.
Negotiation of fine canals is initiated with fine files that are
then advanced to WL and worked until a next larger
instrument may be used.
Conceptually, the final shape is predicted by the last-used
instrument.
A single matching gutta –percha point used for root canal
filling.

48. Thetechniquewaseasytoperforminstraightcanalsof
matureteethexhibitingnaturaltaperbutposedproblemsin
small,curvedcanals.Astheinstrumentsgotlarger,theability
tofinessethestiffinstrumentstodifferentlengthsdecreased
becauseoftherestoringforceofthemetal.Thisoftenresulted
inledging,apicaltransportation,andapicalperforation,or
"zipping"

49. The standardized preparation technique resulted in
procedural errors when used in a curved canal. Dentin was removed
from the inner wall of the canal coronal to the curve and
from the outer wall of the canal apical to the curve.This resulted in
an "hourglass" preparation. In the apical portion the canal was
transported, or "zipped;' when larger, less flexible instruments were
used at the correct working length.

50. Disadvantages
◦Risk of extrusion of debris
◦Alteration of working length
◦Difficult to debride complex canals
◦Possibility of canal deviation

51. STEP BACK PREPARATION
(Telescopic, Serial root canal prep)
Stepbacktechniqueemphasizeskeepingtheapical
preparationsmall,initsoriginalpositionandproducinga
gradualtapercoronally.
Weine,Martin,Walton,Mullaneyadvocatedstepback.
Mullaneydividedthestepbacktechniqueintotwophases:
PhaseI;involvesthepreparationofapicalconstriction
PhaseII:involvesthepreparationoftheremainingcanal.

53. ADVANTAGES DISADVANTAGES
•Morecoronal flare
•Proper apical stop
•Difficult to irrigate apical area
•pushes the debris periapically
•Time consuming
•ledge formation
•Loss of working length

54. Crown-Down (Step-Down)Technique
Goerig et al
shaping the coronal aspect of a root canal first before apical
instrumentation commenced.
PROCEDURE:
Patency of the canal is established (6,8,10 K files)
Coronal 2/3 Preparation : by H-files 15,20 and 25 to working length
depth of 16-18mm or to the point where the file starts binding.
Followed by flaring the coronal segment of the canal with Gates-Glidden
drills (2,3 and 4)
Working length determination by 15k file.

55. A large file (size 60) placed in canal to the level of binding in
watch winding motion.
Process is repeated with sequentially smaller files until WL
reached. (Recapitulation with 15 k files each change of
instrument).
The apical portion of the canal is now enlarged to the
appropriate MAF size which would vary from canal to canal
and from tooth to tooth.
The final canal taper is accomplished by the MAF used in a
circumferential filing motion.

56. Advantages:
Shapingiseasierthanthestepbacktechnique.
Theremovalofcoronalobstructionallowsremovalofbulkof
tissues,debrisandmicroorganismbeforeapicalshaping.
Itminimizestheextrusionofdebristhroughtheapical
foramentherebypreventingpostoperativediscomfort.
Itallowsbetteraccessandcontrolovertheapicalenlarging
instrument,thusdecreasingtheincidenceofzipping.
Allowsbetterirrigantpenetration.
Workinglengthislesslikelytochangewhileusingthis
technique.

57. CROWN-DOWN PRESSURE LESS
TECHNIQUE
Introduced by Marshall & Pappin
Early coronal flaring with Gates-Glidden drills is followed by
an incremental removal of dentin from coronal to apical
direction, and hence, called “crown down” technique.
Straight k-files are then used in a large to small sequence with a
reaming motion and no apical pressure-hence called ‘
pressureless’ technique.

58. After completion of coronal access, determined provisional WL
and size 35 K file introduced in canal without apical pressure.
Flare the coronal part with GG drill no.2 ,3,4 sequentially.
Next step is crown down technique in which a no.60 file is used
with no apical pressure and reaming motion is employed to
enlarge the canal.
Followed by sequentially smaller files, deeper into the canal.
The final step is to enlarge the apical area to the appropriate
master apical file size at the WL.

59. Advantages:
◦Less extrusion of debris
◦Effective in maintaining canal shape
◦Less chance of alteration of working length

60. Double –Flare Technique
Proposed by Fava(1983)
Prepared the canal in a crown down approach untill reached apical third.
Established WL.
Enlarge apical third using larger to smaller files untill WL is reached.
Apical enlargement is done till master apical file
Stepping back with descending files with frequent recapitulations using the
master apical file.

61. Balanced force technique
By Roane & Sabala in 1985
Flex-R files or flexofile are used in this technique.
Thetechniquedescribedaspositioningandpreloadingan
instrumentthroughclockwiserotationandthenshapingthe
canalwithcounterclockwiserotation.
PROCEDURE:
Cronal 3ͬ ͩ is prepared by Crown-down technique
After pressureless insertion of a Flex-R or a Flexofile,
the instrument is rotated 90ͦ clockwise with light apical
pressure.

62. Then rotate counter-
clockwise (180-270˚) with
sufficient apical pressure.
After 2-3 cycles removed
with a prolonged clockwise
rotation.
Sequential files are used in
crown-down fashion before
preparing the apical third to
the appropriate MAF size.

64. Roane firmly believed in enlarging the apical area to sizes larger than
generally practiced.
A minimum enlargement of size 45, 1.5 mm short of the apical foramen in
curved canals, is recommended and
Size 80 in single-rooted teeth, carrying the preparation through to ‘full
length’ of the radiographic apex of the root.
ADVANTAGES:
Reduce canal transportation and ledging.

65. Apical part of the canal enlarged at least 3 sizes more than
IAF ?
Grossman’s –Root canals should be enlarged, regardless of initial
width, to remove irregularities of dentin and to make the walls
of the canal smooth and tapered.
The prepared root canal should be smooth and large enough to
allow adequate debridement and obturation. Ideally , the
minimum size to which a root canal should be enlarged can not
be standardized and varies from case to case. Eg. The canal of
a narrow tooth, such as lower incisor, can not be enlarged as
much as the canal of a lower canine.

67. Conclusion
keystonestosuccessfulrootcanaltherapy–achievedby
propershapingandcleaningoftherootcanalsystemThe
proceduresshouldbedoneprecisely,withthedetail
knowledgeofvarioustechniques,properties,limitationsof
instrumentsandtherootcanalanatomy.