Cleaning and shaping of root canal

1. Presented by:
Rheia Baijal
3271
BDS Final Year

2. INTRODUCTION
Endodontic treatment mainly consists of three
steps:
1. Cleaning and shaping of root canal system
2.Disinfection
3.Obturation

3. What Is Cleaning And Shaping ?
Cleaning- It comprises the removal of all potentially pathogenic contents
from the root canal system.
Shaping- It is the establishment of a specifically shaped cavity which
performs the dual role of-
 three dimensional access into canal
Creating an apical preparation which will permit the final obturation
instruments to fit easily.

4. Objectives of Root Canal Preparation
(given by Schilder)
A.MECHANICAL OBJECTIVES
B.BIOLOGICAL OBJECTIVES
C.CLINICAL OBJECTIVES

5. MECHANICAL OBJECTIVES
A. The root canal preparation
should develop a
continuously tapering
cone.
B. Making the preparation in
multiple plane which
introduces the
concept of “FLOW.”
C. Making the canal narrow
apically and widest coronally.
D. Avoid transportation of
foramen.
E. Keep the apical opening as
small as possible.

6. BIOLOGICAL OBJECTIVES
Procedure should be
confines to the root
canal space.
All infected pulp
tissue, bacteria and
their by products
should be removed
from theRoot canal.
Necrotic debris should
not be forced
peripically
Sufficient space for
intracanal medicaments
and irrigants
should be created.

7. CLINICAL OBJECTIVES
A. Removal of overlying dentine causes smooth internal walls and
provide straight line access to root canals
B. After obturation there should be complete sealing of the pulp
chamber and access cavity so as to prevent microleakage.
C. Tooth should be restored with permanent restoration to maintain it’s
form,function and esthetics and patient should be recalled on
regular basis for evaluation
Removal of overlying dentine
causes smooth internal wallls
and provide straight line access
to root canals

8. INSTRUMENTS USED FOR
RADICULAR PREPARATION
• Broaches
• Files
Hand instruments
• Gates gidden drill
• Protaper
• Profile
• Greater taper
• Quantec file series
• Light speed
• K3 files and Hero 642
Rotary
instruments
LASERS
Automated
(sonic/ultrasonic)

9. DIFFERENT MOVEMENTS OF
INSTRUMENTS

10. Reaming
1)Reaming action: It is a repeated clockwise rotation
of the Instrument which will shave the canal walls
and give a cross sectional preparation approximately
round.
Reamers are usually more effective for this function

11. Filing
2) Filing action: It is a push pull action
without rotation which has a great
efficiency with files than reamers.
The cross sectional appearance of
the prepared root
canal is irregular with general
oval configuration.

12. Combination Of Reaming And Filing
3) Combination: In this technique file is
inserted with a quarter turn
clockwise and apically directed pressure &
then is subsequently withdrawn.

13. Balanced force technique
Insertion -Clockwise 60 degree
Apical pushing with rotation of 120 degree counter
clockwise
Removal by giving a 60 degree rotation clockwise

14. Watch Winding
5 )Watch-winding motion.
Arched arrow indicates a gentle right
and left rocking motion, which causes
the instrument to cut while a light
inward pressure (straight arrow) keeps
the file engaged and progressing toward
the apex.
Arc of rotation is indicated by
the shaded region in the circle .
30 degrees each way.

15. Watch Winding And Pull Motion
6)Watch-winding-and-pull motion. This is used primarily with Hedström files.
1, Inward pressure is maintained (straight arrow), while the file is gently rocked
right and left, through the arc indicated by the shaded region of the circle;
2, when insertion stops, all rotation is ceased and the instrument is withdrawn.

16. Motions Of Instruments For
Cleaning And Shaping
There are six unique motions of files and reamers used in serial
shaping, they are follow, follow-withdraw, cart, carve, smooth, and
patency.
1.Follow- In this file is pre curved to follow canal curvatures.
2.Follow withdraw-In and out motion is given to the instrument.It is done
to create a path for foramen.
3.Cart-Carting actually means transporting, refers to the extension of a
reamer to or near the radiographic terminus. The precurved reamer should
gently and randomly touch the dentinal walls at the radiographic constriction
and "cart" away dentinal debris and pulp remnants
4.Carve- Carving is for shaping. The key is not to press the instrument
apically but simply snuggle into the dentin with a precurved reamer and
shape on withdrawal.
5.Smooth-Smoothing is circumferential filing, is usually accomplished with
files.
6. Patency – it is achieved with files or reamers. It means simply that the
portal of exit has been cleared of any debris in its path.

17. Basic Principles Of Canal
Instrumentation
 There should be a straight line access to the root canal system.
 Copius irrigation should be done in between instrumentation.
 Prepared canal should retain it’s original form and shape
 Exploration of orifice should be done with smaller file to gauge the
canal size and configuration
 Canal enlargement should be done using instruments
in sequential order.
 Flutes should be cleaned and inspected after each
removal.
 Never force the instrument in the canal
 Recapitulation is regularly done to loosen debris.
 Over preparation and too aggressive over enlargement
of curved canals should be avoided.
 Overusing of larger files must be avoided as it may result in further
enlargement of apical opening.

18. Techniques Of Root Canal
Preparations
Two approaches for biomechanical preparation
A. Apical to coronal technique
B Coronal to apical technique

19. VARIOUS OTHER TECHNIQUES HAVE BEEN MODIFIED OUT OF
THESE TWO BASIC TECHNIQUES :
apical to coronal
 STANDARDISED TECHNIQUE OF CANAL PREPARATION
 STEP BACK
 MODIFIED STEP BACK TECHNIQUE
 PASSIVE STEP BACK TECHNIQUE
Coronal to apical
 STEP DOWN
 CROWN DOWN PRESSURELESS
 HYBRID TECHNIQUE OF CANAL PREPARATION
 BALANCED FORCE TECHNIQUE
 REVERSE BALANCED FORCE PREPARATION
 DOUBLE FLARE TECHNIQUE
 MODIFIED DOUBLE FLARE TTECHNIQUE

20. Standardized Preparation
Technique
By Ingle
Determination
of working
length
Select initial
apical file
Circumferential
filing to
increase apical
constriction 2 to
3 files size
greater.
Increased
incidence of
ledging zipping
and perforation

22. STEP BACK TECHNIQUE
Also known as
Telescopic canal preparation / Serial Root canal preparation.
emphasizes on keeping apical preparation small ,in original
position and producing a gradual taper coronally.
Preparation is done in two phases
Phase 1
• Preparation of apical constriction
Phase 2
• Preparation of remaining canal

23. CROWN DOWN TECHNIQUE-
Phase 1
Evaluate Tooth decay causing
pulp exposure
Prepare the access cavity and locate canal orifice

24. Determination of working
length of tooth
Insert the first instrument
with Watch winding motion
with gentle clockwise and
anticlockwise motion of
the file.
Remove the instrument
and irrigate the canal Placement of file to working length

25. Remove intrumnt and irrigate the canal.
Recapitulate using smaller file to break up apical debris and repeat the
process until a size 25-K file reaches the WL
Recaptiulation using smaller file 25 no. file at working length

26. Phase 2
Place next file 1mm short
of working length
Do watch winding
motion,circumferential
filing,irrigation and
recapitulation.
Repeat above steps with
larger files at 1mm
increments from
previously used files
Refine root canal by
master apical file.

27. 30 No file 1 mm
short of working lenght
35 no file 2mm short
of working length
40 No file 3mm short of
working length

28. 45 No. file 4mm short of
working length 50mm file for canal preparation

29. Step Back
preparation
creates small
apical
preparation with
larger
instruments
used at
successively
decreasing
lengths to create
a taper

30. Variations in step back technique
Enlargement of coronal part of
canal using GG drills
Use of smaller GG drills to prepare
mid root level

31. Advantages And Disadvantages
1. Advantages
 More flare at corornal part of the root canal with proper apical
stop.
2. Disadvantages
 Difficult to irrigate apical region
 Chances of pushing debris apically.
 Time consuming
 Iatrogenic errors like ledge formation
in curved canals may occur
 Difficult to penetrate instruments
in canal
 More chances of instrument fracture

32. Modified step back technique
Preparation is completed in apical third of canal
Step back procedure strted 2-3 mm short of apical constriction so as
to give an
almost parallel retention from apical area
This recieves the primary gutta percha point which shows slight tug
back ,when point is removed.

33. Passive Step Back Technique

34. Crown Down Technique
Dentist prepares the canal from crown to tooth.
Morgan and montogomery found that this “crown down pressureless
technique
resulted in rounder canal shape when compare to step back
technique.
Early coronal flaring with gates gidden burs
Incremental removal of dentine from coronal to apical direction
Straight k-type files are used in a large to small sequence with a
reaming motion and no apical pressure

35. Steps
Straight line access to root canal system Access cavity is filled with irrigant

36. Preflaring of
Coronal third of
Canal using GG
Drill (larger first
smaller subsequently)
Excessive use of
GG drill at same level
leads to excessive
cutting of dentine
weakening of roots
and there by coke bottle
appearance in radiograph
Establish working
length with small
instrument after
irrigation and
recapitulation.

37. Use of larger file to
prepare coronal third.
Preparation of canal
at middle third with
subsequently smaller
no. of file.
Apical preparation of
canal with frequent
irrigation of canal system

38. Well Prepared tapered
preparation of the tooth.

39. Balanced Force Technique
Positioning and preloading an instrument through a CW rotation &
then shaping the canal with a CCW rotation
Flex-R file

40. Balanced Force Technique
Engaging
dentine with a
light quarter-
clockwise
turn. (60
degree)
The cutting
stroke- turning
CC 120 degree
and pushing
apically to
prevent it from
backing out of
the canal
Clearing cutting
debris requires another
light quarter-clockwise
turn of 60 degree

42. Step Down Technique
Preparation of coronal third in two phases:
Phase 1- root canal is
penetrated using Hedstorem
files
Phase 2- GG drills are
used to flare the coronal
segment of root canal.
ADVANTAGES

43. Hybrid technique
Combination of step back and crown
down technique
Uses both rotary and hand insrtuments
Hand instruments secure a patent glide path
Tapered rotary instruments efficiently enlarge
coronal canal areas

44. DOUBLE FLARED TECHNIQUE
Canal is explored using small file.
Then canal is prepared in crown down manner using K files in decreasing
sizes.
Step back tecq is followed in 1 mm increments with increasing file sizes

45. Modified Double Flare technique
o Advocated by Saunders & Saunders
o Uses non cutting tipped instruments with
step back technique
o Preparation starts in the coronal part of the
canal

47. ENGINE DRIVEN ROTARY
INSTRUMENTS
Rotary with
alternating cutting
alternating cutting
edges

48. Canal Preparation Using Ultrasonic
Instruments
Suggested by Richman
Movement of file shaft between 0.001-0.004
inch at 20000- 25000/sec frequency .
For free movement of file in canal it should
Not have any binding specially at apical end.

49. Technique

50. MECHANISM OF ACTION
Ultrasonic cavitation
and implosion