This document provides an overview of cleaning and shaping of root canals using hand instruments. It discusses the objectives and techniques of cleaning and shaping, including irrigation, instrumentation motions, and traditional techniques like step-back preparation. Various instrumentation techniques are described, such as step-back, step-down, and hybrid techniques using balanced force concept. The importance of proper shaping to achieve three-dimensional obturation is emphasized.

1. Cleaning & shaping of
root canal system with
hand instruments

2. CONTENTS
• Introduction
• Objectives of cleaning & shaping
• pulpectomy
• Irrigation
• Motions of Cleaning and Shaping
• Precurving
• Traditional cleaning and shaping
breakdownsl

3. • Techniques of preparing root canal
 Step back technique
 Step down technique
 Hybrid technique
 Balanced force concept and technique
 Canal master U technique
 conclusion
 references

4. INTRODUCTION
• Cleaning and shaping are the basics of
endodontic therapy. Most obturation problems
are really problems of cleaning and shaping.
• Even simple canals that are poorly shaped are
difficult to obturate properly, whereas extremely
complex root canal systems can be obturated
properly if the shaping has been accomplished
skillfully.

5. • Over the years, there has been a gradual change in the
ideal configuration of a prepared root canal.
• At onetime, the suggested shape was round and tapered,
almost parallel
• After Schilder’s classic description of “cleaning and
shaping,” the more accepted shape for the finished canal
has become a gradually increasing taper, with the smallest
diameter at the apical constricture,terminating larger at the
coronal orifice

6. • Cleaning refers to the removal of all contents of the root
canal system before and during shaping: organic
substrates, microflora, bacterial byproducts, food, caries,
denticles, pulp stones, dense collagen, previous root canal
filling material, and dentinal filings resulting from root canal
preparation.
• Shaping During this process, instrumentation must give
the system a form that will ensure tissue removal and a
shape that will enhance total filling of the root canal system
in three dimensions. Inadequate shaping causes
inadequate obturation.

7. • Shaping enlarges the canal’s diameter and
smoothes the walls as it removes crevices,
fissures, and irregularities from the system.
• Cleaning is a combined chemical and
mechanical process, while shaping is purely a
mechanical one.

8. OBJECTIVES OF CLEANING &
SHAPING

9. BIOLOGIC OBJECTIVES:
To free the RC system from
 pulp
 bacteria & their endotoxins.

10. MECHANICAL OBJECTIVES
Continuously tapering preparation with narrow
apical diameter
To maintain original anatomy
To maintain position of foramen
To maintain foramen as small as practical
To prepare & thoroughly clean RC system for 3D
obturation

11. • “The Look”
Schilder refers to the look as the radiographic
appearance of three-dimensional obturation,
when all the five mechanical properties have
been achieved.

12. PULPECTOMY
• Complete removal of pulp
tissue should be done before
starting shaping procedures
• Buchanan emphasized the
importance of removing all
pulp remnants before
shaping begins to ensure that
this tissue does not “pileup”
at the constriction and
impede full cleaning and
shaping to that point.

13. • On removal, the instrument should be cleaned
and the root canals irrigated
Irrigation

14. • Principles of Irrigation
– (1) gross debridement
– (2) lubrication
– (3) elimination of microbes
– (4) dissolution of soft tissues,
– (5) removal of the smear layer.
• Accomplishing all five ends requires a combination of at
least two fluids:
– (1) a lavage, lubricant, tissue solvent, and
microbicide
– 2) a chelator or a dilute acid

15. Types of Irrigation Solutions
• Irrigating solution without any chemical
action e.g.
– saline
• Irrigating solution with chemical action
e.g.
– NAOCL
– H2O2
– EDTA (17% aqueous)

16. saline
• In isotonic concentration, it produces no recognized
tissue damage Saline accomplishes gross
debridement and lubrication.
• Caution should be used in storage, loading and
handling. This solution must not be contaminated
with foreign biologic materials before or during use.
• Irrigation with saline sacrifices chemical destruction
of microbiologic matter and dissolution of
mechanically inaccessible tissues (e.g., in accessory
canals and intercanal tissue bridges).
• Isotonic saline is too mild to thoroughly clean
canals.

17. Sodium hypochlorite
• Sodium hypochlorite (NaOCI) is by far the most
commonly used irrigant in endodontic therapy.
• The rate and extent of dissolution are related to the
concentration of the NaOCI solution
• Concentration used 5.25% , 2.5%, 1.25%

18. Hydrogen peroxide
• Hydrogen peroxide is used as an irrigating fluid in
conjunction with sodium hypochlorite.
• When irrigated into a canal flooded with sodium hypo
chlorite an effervescent action takes place, wherein the
two chemicals actively release nascent oxygen and cause
a strong agitation of the canal contents
• Bubbling oxygen rising to the access opening tends to
carry loose debris along with it
• Both chemicals produce some tissue dissolution and
bacterial destruction
• The combined mechanical irrigation is effective the last
irrigant should always be sodium hypochlorite

19. Chelating agents
– Disodium ethylene diamine-tetraacetate
– EDTA
– sodium hydroxide
– cetyl-tri methyl ammonium bromide and water
mixture
• are chelating agents that may be used to irrigate
the canal.
• They remove the smear layer and may be used to
soften obstructing dentin and facilitate removal of
calcific obstructions.

20. • They can soften the dentin throughout the canal
system if they are sealed into the canal between
visits or if they are used for an extended time
during cleaning and shaping.

21. Serial shaping motions
• Cleaning and shaping are dynamically delicate
motions, flowing, rhythmic, and energetic. In order to use
files and reamers efficiently, the movements require
distinction. There are six distinctive motions of files and
reamers.
• Follow
• Follow-withdraw
• Cart
• Carve
• Smooth
• Patency

22. Follow
• Follow is usually performed with files. They are
used initially during cleaning and shaping, or any
time an obstruction blocks the foramen.
• Irrigating, precurving, different kinds of curves,
curving all the way to the tip of the instrument, and
multiple curves in multiple directions of the
instrument are all part of follow.

23. Follow-withdraw
• For follow and withdrawal, again, the file is the
most useful instrument.
• The motion is used when the foramen is reached,
and the next step is to create the path from access
cavity to foramen.
• The motion is follow and then withdraw, or “follow
and pull”, or “follow and remove”. It is, simply, an
in-and-out, passive motion that makes no attempt
to shape the canal

24. Cart
• Carting refers to the extension of a reamer to
or near the radiographic terminus. The
precurved reamer should gently and randomly
touch the dentinal walls and “cart” away
debris.

25. Carve
• Carving is for shaping. Reamers are the best
instruments for carving and sculpting.
• The key is not to press the instrument apically but
simply to touch the dentin with a precurved reamer
and shape on withdrawal, thinking gentleness. The
operator should never forces an instrument by
penetrating to the maximum physical depth.

26. Smooth
• Smoothing is usually accomplished with files. In the
past most endodontic procedures were performed
with a smoothing or circumferential filing motion. If
the previous four motions are followed, smoothing is
rarely required.

27. Patency
• Patency is achieved with files or reamers. It
means simply that the portal of exit has been
cleared of any debris in its path. Again, if the
clinician has been diligent with the other
motions, confirming patency is simplified.

28. • Several motions of manipulation are useful for
generating or controlling the cutting activity of an
endodontic file. These may be referred to as
envelopes of motion, historically
– (1) filing
– (2) reaming
– (3) watch winding
– (4) balanced force instrumentation .
Motions of instrumentation

29. REAMING
• Reaming involves placement of
the instrument toward the apex
until some binding is felt and then
turning he handle more than a full
revolution.
• Clockwise turning will remove
material from the canal by way of
the flutes revolution, whereas
counterclockwise turning will force
material apically.
• The major effectiveness of hard
tissue removal by reaming is in
the insertion of the instrument by
shaving the dentin walls.

30. FILING
• Filing involves placement of
the instrument toward the
apex until some binding is felt
and then removing the
instrument by scraping
against a side of the dentin
wall with little or no revolution
of the handle. This dragging
against the side of the wall is
also referred to as rasping.
• The major effectiveness of
hard tissue removal by filing
is in the outstroke or
withdrawal of the instrument
by dragging the flutes on the
dentin walls.

31. CIRCUMFERENTIAL FILING
• Circumferential filing is a method of filing
whereby the instrument is moved first toward the
buccal [or the labial] side of the canal, then
reinserted and removed slightly mesially. This
continues around the preparation to the lingual
aspect and then to the distal until all the dentin
walls have received rasping.
• This technique enhances preparation when a
flaring method is used by widening the orifice of
the canal considerably, whereas the apical
portion is kept relatively small.

32. Turn-and-pull
• The turn-and-pull cutting motion is a combination of a
reaming and filing motion
• The file is inserted with a quarter turn clockwise and
inwardly directed hand pressure (i.e., reaming).
Positioned into the canal by this action the file is
subsequently withdrawn (i.e., filling).
• The rotation during placement sets the cutting edges
of the file into dentin and the non rotating withdrawal
breaks loose the dentin that has been engaged.
• Schilder recommends clockwise rotation of a half
revolution followed by withdrawal

33. Watch-winding
• Watch-winding is the back-and-forth
oscillation of a file (30 to 60 degrees) right and
(30 to 60 degrees) left as the instrument is
pushed forward into the canal.

34. • It is less aggressive than quarter turn-and-pull motions, as
the tip is not pushed as far into the apical regions of the
canal with each motion and the chances for apical ledging
are reduced.
• Each cut opens space and frees the instrument for deeper
insertion with the next clockwise motion.
• The watch-winding technique is effective with all K-type files

35. Watch-winding and pull
• When used with Hedstrom files, watch-winding cannot
cut dentin with the backstroke. It can only wiggle and
wedge the nearly horizontal unidirectional edges tightly
into opposing canal walls.
• Thus positioned, the engaged dentin is removal during
a subsequent pull stroke.

36. Balanced force
The file is placed in the canal and turned 90,advancing
it into the canal and engaging dentin. The cutting motion
involves turning the file anticlockwise, using a light
apical pressure to prevent it from working its way back
out.

37. Anticurvature filing
• Anticurvature is a method of applying instrument
pressure so that shaping will occur away from the
inside of the root curvature in the coronal and
middle third of a canal.

38. • Abou-Rass, Frank, and Glick described the anticurvature
filing concept for curved canals, emphasizing that during
shaping procedures files should be pulled from canals as
pressure is applied to the outside canal wall.
• Anticurvature pressure application is effective until the
canal contacts the file at three points within the canal.
Beyond there, the canal curvature, not the clinician,
determines the cutting pressure.
• This directionally applied pressure, they suggest,
prevents
– Dangerous midcurvature straightening in curved
canals
– Laceration of a furcal area during preparation

39. Precurving instruments
• A precurved file is a valuable
tool for feeling canal passages
and for moving around
calcification, ledges and
through curved foramina.
• A properly shaped file is curved
smoothly to its tip. Its shape
should accurately replicate the
expected canal curvature.
• Sharp kinks should be
avoided, as they predispose
the instruments to fracture .

41. • “all root canals have some curvature. Even
apparently straight canals are usually
curved to some degree.”
• Canals that appear to curve in one
direction often curve in other directions as
well.
• Prior to the introduction of nickel-titanium
files, one of the first axioms of endodontics
has been to “always use a curved
instrument in a curved canal.”

42. • the bladed part of the
file must be bent all
the way, even up to
the last half
millimeter,
remembering “that
canals curve most in
the apical one-third”.

43. • the most difficult curves
to deal with are to the
buccal and the lingual
because they are directly
in line with the x-ray
beam.
• Their apical orifices
appear on the film well
short of the root apex.

44. TRADITIONAL CLEANING AND
SHAPING BREAKDOWNS
WORKING SHORT
APICAL PREPARATION FIRST
METHODS AND INSTRUMENTS USED

45. Step-Back Preparation
• Weine, Martin, Walton,and Mullaney were early
advocates of step-back, also called telescopic or
serial root canal preparation.
• Designed to overcome instrument transportation in
the apical-third canal, as described earlier, it has
proved quite successful.

46. • This method of preparation has been well
described by Mullaney.
• Mullaney divided the step-back preparation into
two phases.
– Phase I is the apical preparation starting at the apical
constriction.
– Phase II is the preparation of the remainder of the
canal, gradually stepping back while increasing in size.
– The completion of the preparation is the Refining
• Phase IIA and
• Phase IIB
– to produce the continuing taper from apex to cervical

47. • The motion of the instrument is “watch winding,”two
or three quarter-turns clockwise-counterclockwise
and then retraction.
• On removal, the instrument is wiped, cleaned,
recurved, relubricated, and repositioned.“Watch
winding” is then repeated.
• The instrument must be to full depth when the cutting
action is made.
• This procedure is repeated until the instrument is
loose in position.
• Irrigation should be done after each instrument is
removed from the canal.

48. • Then the next size K file is used length
established, precurved, lubricated, and
positioned.
• Again, the watch-winding action and retraction
are repeated.
• Very short (1.0 mm) filing strokes can also be
used at the apex.

49. • This completes the chemomechanical step-
back preparation of the continuing taper
canal.

50. Modified Step-Back Technique
• One variation of the step-back technique is more
traditional.
• The preparation is completed in the apical area, and then
the step-back procedure begins 2 to 3 mm up the canal.
• This gives a short, almost parallel retention form to receive
the primary gutta-percha point when lateral condensation is
being used to fill the canal.

51. • The gutta-percha trial point should go fully to the
constriction, and a slight tug-back should be felt
when the point is removed (retention form).
• This shows that it fits tightly into the last 2 to 3
mm of the prepared canal.

52. Step-Down, Step-by-Step
• In this method, the access cavity is filled with sodium
hypochlorite, and the first instrument is introduced into
the canal.
• At this point, there is a divergence in technique dictated
by the instrument design and the protocol for proceeding
recommended by each instrument manufacturer.
• All of the directions, however, start with exploration of
the canal with a fine, stainless steel, .02 taper (No. 8, 10,
15, or 20 file, determined by the canal width), curved
instrument. It is important that the canal be patent to the
apical constriction before cleaning and shaping begin

53. • Sometimes the chosen file will not reach the
apical constriction, and one assumes that the file
is binding at the apex. But, more often than not,
the file is binding in the coronal canal.
• In this case, one should start with a wider (0.04
or 0.06 taper)instrument or a Gates-Glidden drill
to free up the canal so that a fine instrument
may reach the mid- and apical canal.

54. • Prepare the coronal portion of
the canal to the depth of 16-18
mm or to the beginning of the
curve using Hedstroem files
15,20,and 25 in a
circumferential filling motion,.
In narrow calcified canals sizes
08 &10 should be first used to
enable placement of the
Hedstroem files and establish
patency. They are also used
intermittently between the
Hedstroem files to maintain
canal patency

55. • Gates glidden drills
1,2 &3 are then used
to refine the coronal
preparation, the no 3
drill extending 1-2
mm into the canal
orifice.

56. • This gradually increasing taper is effective in final filling for as
Buchanan pointed out, the “apical movement of the cone into a
tapered apical preparation…only tightens the apical seal.”
• But, as Buchanan further noted, “overzealous canal shaping to
achieve this taper has been at the expense of tooth structure in the
coronal two-thirds of the preparation leading to perforations” and,
one might add, materially weakening the tooth.
• Grossly tapered preparations may well go back to Berg,an early
Boston endodontist, who enlarged canals to enormous size to
accommodate large heated pluggers used to condense warm
sectional gutta-percha

57. • The next sequence of
instruments are used in crown
down fashion
• the instruments are used in a
watch-winding motion until the
apical constriction (or working
length) is reached.
• When resistance is met to
further penetration, the next
smallest size is used.
• Irrigation should follow the use
of each instrument and
recapitulation after every other
instrument

58. Then the apical
preparation done upto
25 size with enough
lubrication, irrigation,
and recapitulation

59. • Merits
• It eliminates cervical dentin constrictures and
reduces canal curvatures, thereby giving the
clinician full tactile awareness in the apical third.
• It allows deeper and earlier penetration of the
disinfecting irrigating solution into the inner
recesses of the canal, thereby effectively
cleaning the coronal two thirds of the canal
before the apical third is approached.

60. • It removes the major portion of the pulp and
infecting microbes before the apical third is
approached, thereby minimizing the risk of
pushing pulpal or microbial irritants into the
periapical region.
• The working length is less likely to change
during apical instrumentation because canal
curvature has been reduced before working
length is actually established

61. Modified crown down technique
• A modified technique described by Ruddle
• Working length determined after pre enlargment with
gates glidden drills (starting from size 1)
• If the clinician chooses 0.02 tapered files to “finish” the
apical one third, Ruddle uses a concept he calls
“Gauging and Tuning.”
• “Gauging” is knowing the cross-sectional diameter of the
foramen that is confirmed by the size of instrument that
“snugs in” at working length
• . “Tuning” is ensuring that each sequentially larger
instrument uniformly backs out of the canal ½ mm.

62. Double-flared technique
• This technique was devised with the fundamental
principle of the coronal-apical approach in mind. The
following steps should be followed
• irrigate the pulp chamber and introduce a small file into
the canal using only gentle push-pull movements to a
working length estimated from radiographs. The aim of
this is to introduce irrigant into the canal.
• Take a further radiograph to check the working length.
• Re-irrigate and introduce a larger instrument into the
canal to a depth of about 14mm ( or in any case coronal
to the curve). This should be loose in the canal but is
used to file the canal walls

65. • Re-irrigate and introduce the next size down 1mm deeper into the
canal maintaining instrumentation coronal to the curve and file the
walls gently. The instrument should not bind in the canal.
• Repeat stage (4) with the next size down.
• Continue until the working length is reached taking another
radiograph if necessary to establish definitive working length. Once
the working length is reached the full length of the canal is prepared
to the appropriate size.
• The canal is now prepared using the step-back technique as
described above except that much less filing in necessary to
establish the final taper. Once again the use of recapitulation is
stressed.

66. • This technique was originally
recommended for straight canals and in
the straight portions of curved canals. It is
contraindicated in calcified canals, young
permanent teeth and in those with open
apices. The principles of the approach ( to
neutralize canal contents and minimize
their extrusion ) may be applied to most
teeth

67. Crown-down pressureless
technique
• Initially, Marshall and Pappin advocated a
Crown-Down Pressureless Preparation
• The aim of this coronal-apical technique is to
facilitate preparation of curved canals without
causing deviation. Rotary action is used to cut
dentine with the apical part of files. The following
sequence is recommended

68. • Determine radicular access length ( the depth to
which a No 35 file penetrated to its point of first
resistance) if this is more than 16mm the coronal
portion of the canal should be prepared to this
length.
• if the file penetrated less than 16mm a
radiograph should be used to determine whether
it is because of canal curvature or calcification.
• If it is due to beginning of a curve the canal is
prepared to the point of first resistance

69. • if not, the canal is widened with smaller files until
the NO.35 file penetrates to 16mm.
• Establish a provisional working length at 3mm
short of the radiographic apex.
• Place a No.35 file into the canal until it
encounters resistance. At this point turn the file
two full revolutions without apical pressure.
Repeat using the next file down until the
provisional length is reached

70. • Establish the definitive working length with
a check radiograph..
• Repeat the sequence of placing a file and
rotating twice without apical pressure until
the working length is reached starting with
a No.40 file.

71. • Repeat the
sequence using
the next
instrument up in
size until the
apical portion of
the canal has
been prepared to
the desired
diameter.

72. • This technique is effective in maintaining
canal shape but the rotary motion
inevitably means a preparation of circular
diameter..

73. BALANCED FORCE CONCEPT
(ROANE and SABALA)
• The balanced force concept was derived from
the physical law which states:For every action
there is an equal and opposite reaction.
• To develop the concept, this law was used to
identify and define actions and reactions that
occur during canal preparation in order to study
them and attempt to define a sequence of
events and motions that could be used to control
endodontic instruments during preparation

74. • Succesful motions were retained and a preparation
method defined which directed high magnitude forces
against small magnitude forces to develop a balance of
action to reaction, making it possible to ignore curvature
during canal preparation.
• To understand the balanced force concept it is
necessary to study the design of preparation
instruments, develop a thorough knowledge of their
characteristics, and learn to recognise their complete
capabilities as well as their specific bahaviour during
movement.

75. • Clinical usage and subsequent physical analysis
indicate that it is best to select a triangular cross-
section K-type file. This type of preparation
instrument offers several advantages over other
cross- sectional designs and instrument types,
when a balance of forces is being sought.
• Most importantly, the K-type design provides
cutting edges with identical rake and clearance
angles regardless of the direction of movement.

76. • Since these angles remain unchanged by direction of
approach with the cutting surface, the K-type instrument
may be used as a bidirectional cutting tool without loss of
efficiency..Bidirectional cutting means that the operator
has two more cutting directions available with a K- type
instrument than would be available if a Hedstroem –type
instrument is used.
• Second, when a triangular configuration is selected, the
cross- sectional mass of each file is reduced, the flute
depth is increased, and the magnitude of the bending
moment or restoring force is decreased

77. . Clinically speaking, a triangular file is predicted to be more
flexible and to apply a lighter restoring force against the
wall of a curved canal during instrumentation. This
means that the triangular ground instrument will be less
likely to transport the canal during preparation.
• Its K-type bidirectional design allows the operator to
select any of four potential cutting approaches,
ie.Insertion, Withdrawal,,Clockwise, or Counterclockwise
rotation.

78. • Restoring force is a statistically applied load which holds
the files cutting surfaces against the curvature in a single
direction and that it is the load which is responsible for a
straightening of the curve during preparation.
• The magnitude of the restoring force developed within a
file is a function of the file’s mass, geometry, and
composition as well as the radius and arc of the
instrumentation curve.
• It’s expression is inversely related to the distance from
the curve to the instrument tip.

79. Consequently, the restoring force is a variable
force and it will increase
• A. If the metal mass increases, either as a result
of shape or instrument diameter;
• B. If the radius of the canal curvature is
decreased
• C. If the arc of the canal curvature is increased
• D. If the distance from the curve to the file tip is
decreased.

80. • Altering the instrument tip removes its capability to
respond to elastic distortion in a concentrated area and
thereby mandates the expression of those forces over
the length of each cutting edge rather than at the file tip.
• Thus, with the terminal points removed, internal
distortions established by the canal curvature generate a
restoring force which is proportioned over the cutting
edges and dispersed enough to allow the relatively
larger magnitude of dentinal hardness to deny noticable
expression..Consequently, the file’s straight profile
becomes unapparent in the completed preparation.

81. • Introduction of tip modification introduces an ability to
enlarge a curved canal even along its inside wall
completely to the apex. This ability does not appear
to exist within the methods tested to date using
standard ground-Ktype instruments.
• File tip modification and use of the balanced force
concept can enable one to easily enlarge a canal
from a size 20 to a size 55 file without recognizable
transportation in the presence of rather significant
canal curvature.

82. Roane’s balanced forces technique -1985
• This technique uses 90° clockwise followed
anticlockwise rotational motion to remove the
dentin.

83. • Three of its main features are as follows.
• Canals are prepared to predesigned
dimensions, of which three are recognized
and designated 45, 60 & 80 according to
the size of apical preparation.
• These dimensions refer to the size of the
file used at the third step back, not to the
master size of the file. Each step back is at
0.5 mm shorter than the previous one

84. • This apical preparation is
known as apical control
zone. it is not prepared to
the apical
constriction/foramen,
which is too variable, but
to the radiographic length
corresponding to the
periodontal ligament
• This technique aims to
create its own prepared
and standardized apical
constriction.

86. • The balanced force technique uses instruments in a step back
manner to initiate preenlargement procedures and to rapidly gain
access to the apical third
• PHASE I FILE INSERTION:
• This is accomplished by reciprocating the handle of the file in a back
and forth motion until it feels snug.
• The handle of the file should then be turned in a 45- to 90-
degree,CW rotation to draw the instrument down, move its cutting
blades deeper into the canal and engage dentin.
•

87. • Phase II file cutting;
• During this phase, the clinician applies two
simultaneous forces on the file handle. The file
handle is rotated CCW while simultaneously
pushed apically. When rotated CCW, the
tendancy of the file to back out of the canal is
balanced by the force of the file being pushed
into the canal.
• During file cutting, it is normal to hear clicking or
popping as dentin is sheared or cut, and carved
off the canal wall.

88. • After the first cutting cycle, the instrument is
extended slightly deeper into the canal in the
manner described in phase I; another phase II
cutting cycle is then repeated. Phase I and
phase II can be repeated between two and four
times; they are ultimately limited by the diameter
of the file or the amount of accumulating debris
or both that potentially prevents the cutting
blades from engaging dentin.

89. • PhaseIII- flute loading
• . The dentin cut in the manner described in
phaseII lies partially in the interblade spaces of
the file and partially in the canal just apical to the
instrument.
• This debris can then be removed from the canal
by rotating the file handle CW, while
simultaneously pulling the instrument coronally.

90. • When flute loading is performed properly, the
position of the file tip never advances apically,
because the tendancy of the file to be drawn into
the canal is balanced by the force of the file
being lifted out of the canal.
After two or three rotations, the file is withdrawn
from the canal; its apical flutes will be loaded
with dentin mud.

92. • ADVANTAGES
• File cutting occurs essentially at the apical extent of the
NiTi file and not along its length. As such the clinician
gains better control of the file and can selectively cut and
remove dentin within a specefic region of the canal.
• The safe ended NiTi file tip stays centered in the root
when activated in phaseII file cutting.Therefore dentin is
safely cut and removed uniformly about the long axis of
the canal and not at the expence of the furcal wall in
multirooted teeth.

93. • It is not necessary to precurve NiTi files to
simulate canal anatomy;they should be
used straight as manufactured.
• Because of its metallurgy and method of
use, the file stays centered in the canal;
thus the canal effectively guides the hand
files in most curvatures.

94. • canal access prepared with the gates glidden drills
by accentuating and smoothening the flare of the
coronal two thirds of the preparation
• It is possible to maintain quite severe canal curvature
with this technique, but the preparations are very
wide and the instruments are prone to fracture. New
tactile sense has to be learned to control the
instruments.

95. Canal master technique
• This technique uses a revolutionary brand of root canal
instrument in a coronal-apical approach.
• its aim is to aid the maintenance of curves using a rotary
instrument designed so that only the apical 1-2 mm is
engaged dentine removal.
• The instruments are both hand held and mechanized.
• The apical 0.75mm of the hand instruments is safe
ended to facilitate maintenance of canal curvature and its
is claimed that this technique avoids the need of
recapitulation.

97. • Intermediate file sizes are available enabling easier
negotiation of curves and a progressive
• development of flare at 0.5mm intervals.
•
• The instruments may have a tendency to fracture.

98. REFERENCES
• Pathways of the Pulp (8th Edition)
• (6th Edition)(7th Edition) ,by Stephen Cohen, Richard C. Burns
• Endodontics, Ingle[3rd,4th Edition]
• Weine – Endodontic Therapy[6th,5th Edition]
• Atlas of Endodontics[2nd Edition]
• Craig – Restorative Dental Materials
• Rudolf Beer – Atlas Of Dental Medicine
• Harty's Endodontics in Clinical Practice by F J Harty & T R Pitt-Ford
• JOE, Vol.11,May 1985

99. • Cleaning and shaping has two special distinctions.
The first is that endodontic therapy is the only dental
procedure that relies so much on “feel”. The tactile
sense is extremely important in endodontic treatment. A
lighter touch, more delicate use of instruments, and
greater restraint by the practitioner will produce better
results. Endodontic treatment is performed primarily
through the sense of touch.
The second distinction of cleaning and shaping is
accountability. In periodontics, orthodontics, and
restorative dentistry, compliance of the patient, their
healing capacity, laboratory quality, home care, and
susceptibility to disease play significant roles in success.
In endodontics, the clinician is the major clinical
variable. Our ability and willingness to deal with root
canal anatomy is the formula for success
conclusion