CLEANING AND SHAPING IN ENDODONTICS

By,
Dr. Aadil Thimwala
Part II (Dept. of Cons. & Endo.)
G.R.I.D.S, Gandhinagar

Outline
 Definitions
 Objectives of cleaning and shaping
 Goals off cleaning and shaping
 Endodontic instruments for cleaning and
shaping
 Ingle and Levine standerdization
 Components of endodontic file
 Classification of endodontic instruments
1. Group I: Hand-operated endodontic
instruments
2. Group II: Low-speed instruments with
latchtype attachments
3. Group III: Engine-driven instruments
4. Group IV: Ultrasonic and sonic
instruments

• Concepts of root canal length and working width
• Different files motions
• Concepts of glide path preparation
• Phases in shaping of root canal system
1. Phase I: Negotiating the canal—“patency filing”
2. Phase II: Coronal pre-enlargement
3. Phase III: Working length measurement
4. Phase IV: Root canal shaping techniques
5. Phase V: Root canal working width
 Procedural errors
 Root canal preparation with ultrasonics
 Laser assisted root canal therapy
 Clinical challenges in root canal preparations

Definitions
Shaping and Cleaning
 Removing the pulp tissue and debris from the canal and
shaping the canal to receive an obturating material.
Pulpectomy
 Complete removal of a normal or diseased pulp from the
pulp cavity of the tooth.
 The operation is sometimes inappropriately referred to as
devitalization.
Endodontic Practice : Grosman13th edn.

Biomechanical Preparation
 The term ‘biomechanical preparation’ as described
by Schilder, involves biological and mechanical
objectives in preparation of root canals.
Essentials of Endodontics : Vimal Sikri.

 The tooth root rarely contains a simple canal ; rather, it is a complex
system containing accessory/lateral canals, fins/apical delta and other
anatomical variations.
 These anatomical intricacies may not be accessible to instrumentation
and hence some chemical agent is necessary to clean these areas.
 Penetration of the chemical agent deep into the canal system requires
prior mechanical preparation.
 Therefore, the term ‘shaping and cleaning’ is gaining popularity
instead of ‘cleaning and shaping’.

Shaping and Cleaning
of Radicular Space
 To debride and disinfect the root canal system
 To shape/contour the root canal walls for the purpose
of sealing the root canal completely with a well
compacted, inert filling material

Schilder’s Objectives of Shaping and Cleaning of the Root Canal
System
Mechanical Objectives
 Should have a continuous, tapering, conical shape, with the narrowest
cross-sectional diameter apically and the widest diameter coronally.
 The walls should taper evenly toward the apex and should be confluent
with the access cavity.
Grossman’s Endodontic Practice : 13th Edn.

 To give the prepared root canal the “quality of flow,” i.e., a
shape that permits plasticized gutta-percha to flow against
the walls without impedance
 Should keep the apical foramen as small as practical.
 Should shape and clean the canal without transporting the
apical foramen.

Biological Objectives
 Confinement of instrumentation to the roots themselves.
 Ensuring that the necrotic debris are not forced beyond the
foramen
 Removal of all tissues from the root canal space
 Creation of sufficient space for optimal obturation of the
radicular space
Grossman’s Endodontic Practice : 13th Edn.

Goals Of Shaping & Cleaning
1. Removal of vital and necrotic tissue from the main root canal.
2. Creation of sufficient space for irrigation and medication.
3. Preservation of the integrity and location of the apical canal anatomy
4. Avoidance of iatrogenic damage to the root structure.
5. Preservation of sound root dentin to allow long-term function of the
tooth.
6. Avoidance of irritation and/or infection of the periradicular tissues.

Clinical Objectives of Biomechanical
Preparation
 The straight line access to canal orifice should be obtained.
 All the overlying dentin should be removed and there should be
flared and smooth internal walls to provide straight line access to
root canals
Textbook of Endodotics: Nisha Garg 3rd Edn.

 In properly shaped canals, instruments and irrigants can go
deeper into the canals to remove all the debris and contents of
root canal
 There should be complete sealing of the pulp chamber to prevent
microleakage into the canal system

Endodontic Instruments
for Shaping and Cleaning
 One time, root canal instruments were made according to
the whim of manufacturers, with no definite specifications
regarding diameter, taper, or length of the cutting blade.
 Ingle and LeVine suggested Guidelines.

Ingle and LeVine’s Standardization
of Endodontic Hand Instruments
 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 millimetre 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.
 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.
 No. 6 and 8 have been added for increased instrument selection.

 In addition, instrument
handles have been color
coded for easier
recognition.

Components of an Endodontic File
 Taper: Taper denotes the per millimetre increase in file diameter from
the tip toward the file handle.

 Flute: It is the groove or relief on the
working surface of the file which collects the
debris as the file cuts through the substrate.
 Blade (cutting edge): It is the working
area of the file and is the surface with the
greatest diameter that follows the flute as it
rotates.
 Land: In certain file designs, a surface
projects axially from the central core to the
cutting edge between the flutes.
 Pitch: It is the distance from one cutting
edge to the next.

Rake angle: On perpendicular
sectioning of a file, the angle which the
leading edge forms with the radius of
the file is known as the rake angle.
 If it forms an obtuse angle, then the
rake angle is considered to be positive.
An acute angle is termed negative rake
angle.
Helix angle: It is the angle the cutting
edge forms with the long axis of the
file.

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

Barbed Broaches and Rasps
 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.
 Barbed broach is introduced until one notes unforced
contact with root canal walls.
 The broach is withdrawn about 1 mm and is rotated 60° to
engage the pulp tissue; it is withdrawn again to remove the
pulp tissue.

K-type Reamers and Files
 1900s, Kerr Manufacturing Company
designed and manufactured K-type
endodontic instruments.
 Manufactured from round, tapered piano wire
(carbon steel).
 The stainless steel wire is ground along its
long axis into a four-sided (square cross-
section) or three-sided (triangular cross-
section).
 Number of flutes twisted into each blade of a
similar-sized instrument determines whether
that instrument is a reamer (less flutes) or a
file (more flutes).

Modifications
K-flex file: Rhomboidal or diamond-shaped blanks have
been twisted to produce a file called K-flex
(SybronEndo/Kerr, USA).
 The manufacturer claims that this design increases the
flexibility and cutting efficiency of the instrument.
 The rhomboidal blank produces alternating high and low
flutes that are supposed to make the instrument more
efficient in removal of debris.

Flex-R file: The stainless steel file’s metallic memory to
return to its original position increases the tendency to
transport or ledge the canal.
 A reduction in the cutting tip angle makes the file stay more
cantered within the canal and enables a more
circumferential cutting action.
 This modified-tip file has been marketed as the Flex-R file
(Moyco/Union Broach, USA).

Hedstroem Files
 Also known as H-files
 Manufactured from a round stainless steel wire
machined to produce spiral flute.
 Resembling cones or a screw.
 Has a higher cutting efficiency than K-
instruments, but it is fragile and fractures easily.
 Better cutting efficiency is attributed to its more
positive rake angle

Modifications
 Safety Hedstroem
 Hyflex file: It has a cross-section which presents an “S”
shape instead of the traditional single-helix teardrop cross-
section
 Unifiles: They are machined from round stainless steel
wire by cutting two superficial grooves to produce flutes in
a double-helix design
 S-file: It has a double-helix cross-section and is a variation
of the Unifile

Group II: Low-Speed Instruments
with Latch-Type Attachment
 Gates-Glidden drills
 Peeso reamers
Gates-Glidden Drills
 The Gates-Glidden drill has a long, thin shaft
ending in a flame-shaped hea.
 The flame head cuts laterally and is used with
gentle, apically directed pressure

Peeso Reamers
 Has long, sharp flutes connected to a thick shaft.
 Cuts laterally and is primarily used for the preparation of
post space.

Group III: Engine-Driven Instruments
Nickel–Titanium Rotary Endodontic Instruments
 Alloy composed of nickel and titanium.
 nitinol exhibits shape memory, i.e., the ability to return to its original
shape once the stress is removed.
 This has led to the development of numerous types of endodontic
instruments which can be employed in a truly rotary or 360° revolution
within a curved root canal.

Reciprocating Instruments
 Function at unequal bidirectional angles.
 Counterclockwise engaging angle is five times the clockwise
disengaging angle and is designed to be less than the elastic limit of
the file
 Strategically, after three counterclockwise and clockwise cutting cycles,
the file will have rotated 360°, or one complete circle.
 This novel reciprocating movement allows a file to progress more
readily, cut efficiently.

Self-Adjusting File
 The file three dimensionally adapts both
longitudinally and along the cross-section of the
root canal system.
 This results in a uniform cutting action of the
dentin from the canal walls (60–75 μm thick) and
preserves the basic shape of the root canal.
 SAF system consists of a hollow compressible
nickel–titanium lattice with a thin-walled pointed
cylinder 1.5 or 2.0 mm in diameter.

 Operated with a modified KaVo vibrating handpiece generating 3,000–
5,000 vibrations/min at amplitude of 0.4 mm.
 Another advantage : continuous irrigation by a silicon tube to the
irrigation hub on the file
 The device operates with an in-and-out manual motion using two cycles
of 2 minutes each for a total of 4 min/canal.

Phases in Shaping
of the Root Canal
Phase I: Negotiating the canal—“patency filing”
Phase II: Coronal pre-enlargement (recommended for certain
shaping techniques)
Phase III: Working length measurement
Phase IV: Root canal shaping techniques
Phase V: Root canal working width

Phase I: Negotiating the
Canal—“Patency Filing”
“Concept of creating a path up to the working length
without blocking or altering the original root canal
anatomy is known as patency filing”.

 Usually performed with a size 10 or smaller K file
instrument that is negotiated passively just through the
apical foramen.
 This helps in maintaining a continuous and clear path to
the apical foramen by removing debris.
 Buchanan defined ‘small K-file, which passively moves
through the apical constriction without widening the
apical constriction’

i. Favoring patency filing
 Cleans apical constriction/foramen area
 Maintains working length
 Prevents packing of debris at the apical constriction end
 Help keeping apical zone area free of microorganisms.
ii. Disfavoring patency filing
 May push debris into periapical areas
 May push microorganisms into periapical area
 May injure the configuration of apical constriction.

Phase II: Coronal Pre-enlargement
 The working length of the tooth should be determined only after
coronal pre enlargement of the canal is completed.
 Coronal pre-enlargement is achieved with the help of orifice
enlargers or with Gates-Glidden drills.
Potential Advantages
 Prevents premature binding of the shaping instrument to the canal
walls
 Removes the coronal third debris before the shaping instruments
negotiate the apical third.
 This reduces the potential for extrusion of debris beyond the
working length

 Enables better and deeper penetration of irrigant earlier in the
preparation, reducing the risk of blockage of apical foramina with
dentine “mud”.
 It allows better tactile discernment and control over apical
instrumentation.
 Can be done in 2 ways :
Gates
Glidden
drills
Niti
orifice
enlargers

Phase III: Working Length Measurement
“Working length is defined as the distance from a coronal
reference point to the point at which canal preparation and
obturation should terminate”
Reference point:
• Site on occlusal or the incisal surface from which
measurements are made.
• It should be stable and easily visualized during
preparation.

Methods of Determining Working Length
I. Radiographic methods
Ingle’s technique (Recommended)
Others
–– Best’s method
–– Bregman’s method
–– Bramante’s technique
–– Grossman’s method
–– Weine’s method

Kuttler’s method
X-ray grid method
Xeroradiography
Direct digital radiography
II. Electronic apex locators
III. Nonradiographic methods (not recommended)
Tactile sense
Apical periodontal sensitivity
Paper point method

INGLE’S
RADIOGRAPHIC
TECHNICHUE
1
2
3
4

Weine’s Modificaiton
No resorption - subtract 1 mm
Periapical bone resorption - subtract 1.5mm
Periapical bone + root apex resorption - subtract 2 mm

GROSSMAN METHOD/MATHEMATICAL
METHOD OF WORKING LENGTH
DETERMINATION
Disadvantages
Wrong readings can occur because of:
• Variations in angles of radiograph
• Curved roots
• S-shaped, double curvature roots.
Textbook of endodontics: Nisha Garg 3rd Edn.

Radiographic Grid
 It was designed by Everett and Fixott in 1963.
 It is a simple method in which a millimeter grid is
superimposed on the radiograph
 This overcomes the need for calculation
 But it is not good method if radiograph is bent during
exposure.

ELECTRONIC APEX LOCATORS
 Used to locate the apical constriction or
cementodentinal junction or the apical
foramen.
 The term apex locator is a misnomer,
because they are used t used to locate the
apical constriction or cementodentinal
junction and not the radiographic apex.
 The ability to distinguish between minor
diameter and major diameter of apical
terminus is most important.

Concept
 WL is determined by comparing the electrical
impedance of the periodontal membrane with that of
the oral mucosa.
 Both of which should be similar at 6.5 KΩ
 This is done with the help of an electronic apex
locator cord that has two ends.
 One end is termed as a “lip hook” that is kept in
contact with the oral mucosa of the patient while the
other end is termed as “file holder”
 When the endodontic file touches the soft tissues of
the periodontal membrane, the electrical-resistance
gauges for both oral mucosa and periodontal
ligament would have similar readings
Endodontic practice : Grossman 13 edn.

Classification of Electronic Apex Locators
Resistance-based electronic apex locator:
 These are the first generation of apex locators which were
developed based on the resistance principle.
 Measures opposition to flow of direct current
 Based on the principle that resistance offered by periodontal ligament
and oral mucous membrane is the same, i.e. 6.5 K Ohms
 Worked best in dry canals.
 The presence of pus, pulpal tissue, blood, and irrigants leads to
inaccurate readings
Endodontic practice : Grossman 13th Edn.
Textbook of endodontics : Nisha garg 3ed edn.

Low-frequency apex locator:
 In order to overcome the problems associated with the resistance based
apex locators, Inoue introduced the concept of impedance-based apex
locators.
 Second generation apex locators.
 Measure opposition to flow of alternating current or impedance.
 Apex locator indicates the apex when two impedance values approach
each other.
 Apex locator had to be calibrated with the periodontal sulcus prior to
each use.
 This procedure was technique sensitive

High-frequency apex locator
 Based on the fact that different sites in canal give difference in
impedance between high (8 KHz) and low 400 Hz) frequencies.
 A high-frequency (400 kHz) wave, as a measuring current, produces a
more stable electrode
 The difference in impedance is least in the coronal part of canal
 The impedance is the greatest at cementodentinal junction.
 More appropriately, they should be termed as “Comparative
Impedance” because they measure elative magnitudes of impedance

Dual-frequency apex locator:
 Determine the canal terminus as the difference between two impedance
values at two different frequencies.
Multiple-frequency apex locator:
 Uses two wavelengths: one high 8 kHz) and one low (400 Hz)
frequency
 Assesses the apical terminus by the simultaneous measurements of the
impedance of two different frequencies that are used to calculate the
quotient of the impedances
 Current apex locators are based on this principle.

Functional Motions of Instrumentation
Reaming: The instrument is used with a clockwise
rotating–pushing motion, limited to a quarter to
a half turn, and disengaged with a mild pulling
motion when bound
Filing: Filing indicates a push–pull motion with
the instrument.
 The instrument is placed into the canal at the
desired length, pressure is exerted against the
canal wall, and the rake of the flutes rasps the
wall as the instrument is withdrawn without
turning and the pressure is maintained
throughout the procedure.

Combination of Reaming and Filing
 File is inserted with a quarter turn clockwise and apically directed pressure (i.e.
reaming) and then is subsequently withdrawn (i.e. filing).
 File edges get engaged into dentin while insertion and breaks the loose dentin
during its withdrawal.
 This technique has also shown the occurrence of frequent ledge formation
 To overcome these shortcomings, this technique was
modified by Schilder.
 Clockwise rotation of half revolution followed by directing the
instrument apically.
Textbook of Endoddontics : Nisha Garg 3rd edn

Watch winding: The instrument is reciprocated back
and forth in a clockwise–counterclockwise motion and
then retracted to remove the debris.
Circumferential filing: Following the cleaning and
shaping of the root canal with a small reamer and
reaming to the root apex (working length), the same-
size file is inserted into the root canal to the apex,
laterally pressed against one side of the canal wall and
withdrawn with a pulling motion

Anticurvature filing: This motion was described by Abou Rass and Jastrab.
 The furcal wall of the canals in the mesial roots of molars is prone to
perforation during coronal enlargement of the canals.
 In order to prevent this error, anticurvature filing is advocated wherein the top
of the handle of the instrument is pulled into the curvature while the shank end
of the handle is pushed away from the inside of the curve (anticurvature).
 This motion balances the cutting flutes against the safer part of the root canal.

Balanced force technique:
 Oscillation of instrument right and left with different arcs
 Instrument is inserted into the canal by moving it clockwise with one quarter
turn—to cut dentin, it is rotated counter clockwise simultaneously pushing
apically to prevent it from backing out of the canal—file is removed by rotating
file clockwise simultaneously pulling the instrument out of the canal

Root Canal Preparation: Concepts/Terms
A. Apical gauging:
 Apical gauging implies measuring/ assessing the apical diameter of the
canal, where the instrument fits snuggly and resist further apical
movements.
 This ensures apical terminus of the
prepared canal
 Ni-Ti instruments are preferred for gauging
because of their flexibility
 The gauging instrument is inserted
straight in and straight out, without any rotation.
 Done after preparation of root canal.
Essentials of endodontics : Vimal sikri

B. Apical tuning:
 Apical tuning implies a confirming parameter, whereby the apical
diameter of the master apical file represents the true diameter the root
canal.
 Tuning is a clinical activity of recapitulating using series of successively
larger instruments.
 Clinically, the file that goes full length represents the ‘true apical
diameter’ of the canal (each successive larger instrument backs out of
canal with an interval of 0.5 mm).

C. Apical scouting:
 Similar to apical gauging, implies determining the cross-section
diameter of the apical third of the root canal.
D. Coronal scouting:
 The process of determining the cross-sectional diameter of
coronal 2/3rd of the root canal.
 Scouting files also analyze the site of curvature in the root
canal (how far the canal is straight from coronal opening
and from where the curvature begins)

E. Apical stop/apical seat:
 A matrix of dentin or other material at the apical end of root canal
preparation.
 Apical seat implies lack of complete barrier, but presence of
constriction; whereas, apical stop means complete barrier at the
preparation end.
F. Apical control zone:
 Mechanical alteration created in the apical third of the root canal.
 This area (around 1.5 mm from the apical constriction) affects the
rheology of gutta-percha and provides resistance form against the
condensation pressure of obturation

Phase IV: Root Canal Shaping Techniques
Techniques of Shaping and Cleaning
1. Step-back technique
(a) Conventional step-back
(b) Passive step-back
(c) Modified step- back
2. Crown-down (step-down) technique and its modifications
(a) Crown-down pressureless
(b) Double flare
(c) Balanced force
(d) Modified double flared technique
3. Hybrid technique

A. Starting at the apex with fine instruments and working up to
the orifice with progressively larger instruments, this is Step
back technique.
B. Starting at the orifice with larger instrument and working up to
apex with larger instruments, this is Crown down technique.
A B

STANDARDIZED PREPARATION
TECHNIQUE
 It was introduced by ingle.
 Standardized reamers of increasing sizes were used sequentially to
enlarge the apical part of the canal
 It uses the same WL definition for all instruments introduced into a
root canal.
 It relies on the inherent shape of the instruments to impart the final
shape to the canal.

Disadvantages
 Chances of loss of working length due to accumulation of dentin debris.
 Does not take into consideration the elliptical forms and large diameter
of root canals.
 Obturation with conventional techniques does not provide adequate
sealing of root canal confines

Step-Back Technique
Conventional Step-Back (Telescopic) Technique
 The canal is enlarged first in the apical third to at least a No. 25 or 30
instrument.
 Then the middle third and coronal thirds sequentially shaped.
 Mullaney divided the step-back preparation into two phases :
 Phase I: It is the apical preparation starting at the apical constriction.
 Phase II: It is the preparation of the remainder of the root canal,
gradually stepping back while increasing in size.

Prepare the access
cavity and locate
the canal orifices
1 2
Place the first smaller
instrument upto the
working length slowly
in watch winding
motion.
3 Prepare with apex
upto desired
diameter. Ex no 25
4 Irrigate the canal and
confirm the patency
using smaller no. file
Textbook of Endodontics : Nisha garg 3rd edn

Canal is further
prepared using
sequentially larger
instrument 1 mm
short of the
instrument No. 30
5
Another larger
instrument used
for further shaping
1 mm short of
previously shaped
instrument. No 35
6
Canal is further
prepared using
sequentially larger
instrument 1 mm
short of the
instrument No. 40
7
45 50

PASSIVE STEP BACK TECHNIQUE
 Developed by Torabinejed.
 Involves the combination of hand (files) and the rotary
instruments (Gates-Glidden drills and Pesso reamers) to attain
an adequate coronal flare before apical root canal preparation.
 Provides gradual enlargement of the root in an apical to coronal
direction without applying force

 Establish the correct working length using a number 15
file.
 After this additional files of number 20, 25, 30, 35 and
40 are inserted into the canal passively.
 Number 2 Gates-Glidden drill is inserted into mildly
flared canal to a point, where it binds slightly.
 Pulled back 1 to 1.5 mm and then activated. With up and
down motion and slight pressure, the canal walls are
flared.
 Similar fashion, number 3 and 4 Gates- Glidden drill are
then used coronally

Progressive Enlargement Technique
 Advocated by Backman et al in 1992
 Uses K files as well as H files in prepation
 Three phases-
1. Apical preparation
2. Progressive filing
3. Coronal 2/3rd filing
JOE , 18: 1 :1992 : 19-24

 After using a # 15 file in the apical
preparation, a #20 file was placed into the
canal to at least one-half the working length,
used with a filing motion (push-pull), and
worked around the canal walls
circumferentially.
 Then a #2 Gates Glidden drill was used to
enlarge the canal 5 mm apical to the orifice
or to a point where the canal curvature
prevented penetration to this depth.
 Then a #3 Gates Glidden drill was used to
enlarge the canal to a level approximately 3
mm apical to the orifice or to a point where
the canal curvature prevented penetration to
this depth.
JOE , 18: 1 :1992 : 19-24

 In the apical preparation, a curve was placed in the most apical portion
of the file.
 The curved file was inserted into the canal and worked apically using a
stem-winding motion and light apical pressure.
 Once the file reached working length, it was withdrawn several
millimeters, then worked to length and withdrawn again.

 After the apical preparation, the progressive filing began with a K file
one size larger than the largest file used in the apical preparation and
progressed sequentially to 20 additional units.
 Beginning with the first file, a stemwinding motion was used to work
the instrument down the root canal to where it bound.
 The file was withdrawn slightly and then worked using a filing motion
(15 to 20 strokes).
 The next larger file was then worked into the root canal until it bound,
was withdrawn slightly, and then worked using a filing motion.

 The coronal two-thirds filing phase wa accomplished with a Hedstrom
file the same size as the largest K file used in the progressive filing
series.
 The length was set 2.5 mm coronal to the working length.
 The file was flexed against the walls of the canal, worked with a filing
motion, and was continued around the periphery of the canal until all
of the walls felt smooth and clean
 Advantages-
- Can be used in small curved canals
- Original apical root cana curvature
maintained

Crown-Down (Step-Down) Technique
Access cavity
preparation with
no pulp chamber
obstructions
1
Fill the access
cavity with an
irrigant and start
preflaring of the
canal orifices
2
Use of Gates-
Glidden for
preflaring3
Establishing
working length
using a small
instrument
4

Use of larger
files to prepare
coronal-third5
Preparation of
canal at middle-
third6
Apical
preparation of
canal7
Prepred tooth

Crowndown pressureless technique.
 Suggested by Marshall and Pappin.
 Early coronal flaring with Gates-Glidden drills is followed by an
incremental removal of dentin from coronal to apical direction.
 Straight K-files are then used in a large to small sequence with a
reaming motion and no apical pressure
 Hence pressureless technique

Canal Master Technique
 Introduced by Wildey and Senia
 Uses Canal Master instrument (SW Instrument):
(1) It replaces the usual cutting tip with a
noncutting pilot. The pilot helps limit
transportation of the canal and guides the
instrument to the foramen.
(2) The cutting segment of the instrument
(cutting head) is reduced from the standard
16 mm to 2.5 to 4.0 mm.
(3) The diameter of the instrument’s smooth
round shaft remains constant and is reduced
to increase its flexibility.
OOO :67 : 2 : 198-208 : 1989

HYBRID TECHNIQUE
 Combination of step-down instrumentation followed by a step-back
technique.
Advantages
 Ability to shape the canal predictably with a combination of hand and
rotary stainless steel instruments.
 Optimizes the advantages of crown-down and step-back techniques.

1
Achieving patency with a precurved
No. 10 or smaller K-file
Passive pressureless placement of sequential sizes of # 15, 20, and 25
K-files to the point of canal binding
Coronal pre-enlargement with Gates-Glidden drills in the sequence of
No. 3, followed by No. 2, and then No. 1
(not beyond 3–4 mm into the root canal orifice)
Establishing the working length with a size 15 K-file
Placement of size 40 or smaller
K-file to the point of canal binding
(to a length 1 mm beyond the depth of insertion of GG drill No.1)
CROWN-DOWNINSTRUMENTATION

2
Enlarging the working length from size 15 K-file to recommended
master apical file sizes
Canal preparation is done with sequential use of progressively larger
instruments placed successively short of the working length
This step-back procedure is perfomed until the middle third to
obtain a continuous tapering canal preparation shape
STEP-BACKINSTRUMENTATION

DOUBLE FLARE TECHNIQUE
 It was introduced by Fava.
 Canal is prepared in crown down manner using K files in decreasing
sizes.
 After this, step back technique is followed in 1 mm increments with
increasing file sizes
Indications
• Straight root canals.
• Straight portions of curved canals of mature teeth.

Technique
 The access opening is done.
 The endodontic treatment of a tooth has to be
performed whose estimated length is 22 mm (crown
measures about 10 mm and the root about 12 mm)
 The measurement to the end of the middle third
would be 18 mm.

 Crown down till upto middle third and then upto working length.
File no. 80 14 mm
File no. 70 15 mm
File no. 60 16 mm
File no. 55 17 mm
File no. 50 18 mm
 The following sequence of instrumentation is followed in the next steps:
File no. 45 19 mm
File no. 40 20 mm
File no. 35 21 mm
File no. 30 22 mm
 After this, the flared preparation as proposed by Weine
File no. 30 22 mm
File no. 35 22 mm
File no. 40 22 mm
File no. 45 21 mm
File no. 40 22 mm
File no. 50 20 mm
File no. 40 22 mm
File no. 55 19 mm
File no. 40 22 mm

Advantages
 Greater taper in the cervical and middle third such that removal
of canal contents is more effective.
 Improved quality of root canal filling when compared to
conventional technique.
 The flared technique maintains the root canal shape and
produces neither the hour glass appearance nor the apical zip

BALANCED FORCE TECHNIQUE
 Roane et al. introduced the ‘‘Balanced Force’’ concept of canal
preparation in 1985.
 The concept came to fruition, they claimed, with the development and
introduction of a new K-type file design, the Flex-R File.
 The technique is ‘‘positioning and preloading an instrument through a
clockwise rotation and then shaping the canal with a counter clockwise
rotation.’

 After pressureless insertion of a Flex-R or a Flexofile, the instrument is rotated
clockwise, 90°using only light apical pressure.
 The instrument is then rotated counterclockwise, 180°–270°, and sufficient
apical pressure is used to keep the file at the same insertion.
 Then another clockwise for 90° and 270° counterclockwise and then full
rotation.
Endodontics: John Ingle 6th Edn.

The reactions which occur along the
blade inclines of a K-type file during
clockwise and counterclockwise
rotation
- JOE:11:5, 1985

Glide path preparation
 Smooth radicular tunnel from canal orifice to
physiologic terminus.
 Its minimal size should be a “super loose No.
10” endondontic file.
 Glide path creation is essential for prevention
of rotary file separation and most effective
rotary use.
ENDODONTOLOGY , 26:1: 217- 2222014

 It can be of two types
1. Manual glide path
2. Mechanical glide path
 Manual glide path is achieved using watch-winding
or continuous filing motion.
 Mechanical glide path is achieved using various
tools

Reciprocating hand pieace by
Micro mega

QUANTEC INSTRUMENT
TECHNIQUE
 Quantec instruments (Sybron Endo/Analytic; Orange, Calif.) are more
like reamers.
 They are recommended for hand instrumentation techniques.
 Three phases:
1. Negotiation,
2. Shaping, and
3. Apical preparation

Negotiation
 Explore the root canal with a
10 or 15 No. 0.02 taper K file.
 Advance quantec No. 25,
0.06 taper instrument, in a
reaming action, from canal
orifice to just short of the
apical third.
 Use ISO 0.02, No. 10 or 15
file, to create a “glide path” to
working length.
 Then use No. 20 and 25, 0.02
instruments to clean and shape
the apical third

 Shaping Use No. 25, 0.06 taper Quantec instrument
in a reaming action, as far down the canal as it can
go.
 Then use No. 0.05, 0.04 and 0.03 tapers Quantec
instruments until the apical stop is reached.

PROTAPER FILES
 Introduced by Dr. Clifford J. Ruddle and Dr. John
West
 ProTaper files have a triangular crosssection and is
variably tapered across its cutting length.
 The progressively tapered design improves
flexibility, cutting efficiency and the safety of these
files.
 The ProTaper system consists of three shaping and
three finishing files.
 Designed for rotary as well as hand filing.

Clinical technique
 Establish a smooth glide path.
 Prepare the coronal third of the canal by
inserting S1 into the canal using passive
pressure.
 Irrigate and recapitulate the canal using
number 10 file.
 In shorter teeth, use of Sx is
recommended.
 After this, S1 is worked up to the estimated
canal length.
 The canal then sequentially enlarged using
S2, F1, F2, F3 files.

Advantages of ProTaper Files
 ProTaper files have modified guiding tip which allow them to follow
canal better.
 Variable tip diameters of ProTaper files allow them to have specific
cutting action in defined area of canal without stressing instrument in
other sections.
 Changing helical angle and pitch over the cutting blades of ProTaper
files reduce the instruments from screwing into the canal.

PROFILE SYSTEM
 Profile instruments system was introduced by Dr Johnson in 1944.
 Earlier profile system was sold as series 29 instruments.
 After this, profile series were introduced with greater tapers of 19 mm
lengths and ISO sized tips.
 Suggested rotational speed is 150 to 300 RPM.
 The negative rake angle of profiles makes them to cut dentin in
planning motion.

Clinical Technique
 Create a glide path with small no. 15 and mo. 20 files.
 Use orifices shapers sizes 4, 3, 2, and 1 in the coronal third of the canal.
 Perform crown down technique using the profile instruments of
taper/size 0.06/25, 0.06/20, 0.04/25 and 0.04/20 to the resistance.

 Now determine the exact working
length
 Complete the crown down procedure
up until this length.
 Use profile 0.04/20, 0.04/25 for apical
preparation
 Now final flaring is done using profile
0.06/20 short of working length to
merge coronal and apical preparation

Advantages
1. Presence of radial land and noncutting tip keep the profiles
selfcentered.
2. Also avoids risk of zip or transportation of canal.
3. Presence of 20° helical angle allows effective removal of dentin debris
4. Presence of radial land prevents its screwing into the canal

GREATER TAPER FILES (GT FILES)
 Possess a U-shaped file design with ISO tip sizes of 20, 30 and 40 and
tapers of 0.04, 0.06, 0.08,.010 and 0.12.
 Accessory GT files for use as orifice openers are available in sizes of
0.12 taper in ISO sizes of 35, 50, 70 and 90.
 Negative rake angle makes them to cut the dentin in planning motion.

Clinical Technique
 Obtain a straight line access to the canal orifice
 Establish the glide path using No. 15k file.
 Lubricate the canal and use GT files (0.12,
0.10, 0.08 and 0.06 taper) in crown down
fashion at 150 to 300 rpm.
 When GT file reaches the two-thirds of
estimated working length, establish the correct
working length.
 Select the final shaping instrument and
penetrate in canal steadily.

LIGHT SPEED SYSTEM
 “light” touch is needed as “speed” of instrumentation is
increased.
 Have noncutting tip with Gates- Glidden in configuration
and are available in 21, 25, 31 and 50 mm length.
 Half sizes of light speed instrument are available in
numbers 22.5, 27.5, 32.5.

Clinical Technique
Three special instruments are used:
1. Initial apical rotary (IAR) - begins to cut canal walls at working length.
2. Master apical rotary (MAR) - Last instrument to perform the apical
preparation.
3. Final Rotary (FR) - Last step back instrument which completes the step back
procedure.
Obtain
straight line
access
Use of initial
apical rotary in
canal
Use of light
speed
instrument in
forward and
backward
movement
Use of light
speed
instrument in
step back
procedure

Procedural Errors
Transportation
 “the initial deviation of the
original root canal pathway
by the removal of dentinal
wall on the outer curve and
may result in the formation
of new canal pathway”
 More aggressive the tip is,
the more likely it is to start
creating its own path or
“transport” the canal
Common complication in Endodontics : Priyanka Jain

External
transportation &
Elbow
“the area of the root canal system
immediately coronal to the
transported or zipped irregular
area.”

Ledge
 “An iatrogenic error created
during instrumentation of the
root canal system resulting in an
irregularity in the surface of the
root canal system that result in
the creation of an artificial step
within the root canal wall that
prevents file placement beyond
the irregularity”
 Continuous instrumentation short
of the working length can force
the file tip to start deviating from
the original canal anatomy and
start creating its own path.

Zipping
 “Iatrogenic error created during
instrumentation of the root canal system
resulting in a tear-drop irregularity in the
outer wall of the apical third of a curved
root canal system”
 Basically a transportation of the outer
wall that results in a reverse-taper at the
apical third.
 The term “apical zip” was first introduced
by Weine and Kelly in 1975.

Phase V: Root Canal Working Width
Traditional Concept
 Enlarge a root canal at least three sizes beyond
the size of the first instrument that binds
 Enlarge the canal until clean, white dentinal
shavings appear in the flutes of the instrument
blade.

Current Concept
 The minimum size to which a root canal should be enlarged cannot be
standardized and varies from case to case.
 The factors that should be taken into consideration before deciding the
optimum size of enlargement areb-
1. Initial canal width
2. Whether the root canal is vital, calcified, or infected.
3. Presence or absence of periradicular pathology/ resorption.
4. Canal configuration, with more attention to be given to complex
anatomies like a C-shaped canal and the isthmus region.

Endodontic Practice : Grossman 13th edn.

CANAL PREPARATION USING
ULTRASONIC INSTRUMENTS
 Use of ultrasound in endodontic therapy was suggested in 1957 by
Richman.
 The machines transmit low frequency ultrasonic vibration
by conversion of electromagnetic energy to the mechanical
energy to produce oscillation of file.
 File oscillates at the frequency of 20,000 to 25,000
vibrations/seconds

Technique
 Apical third of the canal should be prepared to atleast size 15 file
 After activation, ultrasonic file is moved in the circumferential manner
with push-pull stroke along the walls of canal.
 File is activated for one minute. This procedure is repeated till the apex
is prepared to atleast size 25.

Advantages
 Less time consuming.
 Produces cleaner canals because of synergetic relation ship
between the ultrasound and the sodium hypo chlorite.
 Heat produced by ultrasonic vibration increases the chemical
effectiveness of the sodium hypochlorite.
Disadvantages
 Increased frequency of canal transportations.
 Increased chances of overinstrumentation.

CANAL PREPARATION USING SONIC
INSTRUMENTS
 Design of sonic instruments is similar to that of ultrasonics.
 Consist of a driver on to which an endosonic file is attached.
 The oscillatory pattern of driver determines the nature of movement of
the attached file.
 There is longitudinal pattern of the vibration when activated.
 Sonic system uses three types of file system for root canal preparation
1. Heliosonic,
2. Rispisonic and
3. The canal shaper instruments

LASER ASSISTED ROOT CANAL THERAPY
 Weichman and Johnson in 1971 were the first to suggest the use of
lasers in endodontics.
 Benefits : ease of using it and great degree of patient comfort during
and after the procedure.
 Laser beam are delivered through the optical fiber with the diameter of
200 to 400 mm equivalent to size 20 to 40 number file.
 Bahcall et al in 1992 found that though the use of Nd:YAG laser can
produce cleaner canals, but heat produced by it may damage the
surrounding supporting tissues

 Hibst et al showed that use of Er:YAG laser may pose less thermal
damage to the tissues because it causes localized heating thereby
minimizing the absorption depth.
 Recently a new root canal treatment using the Er, Cr:YSGG has been
introduced.
 The device which provides such a treatment is the waterlase—
hydrokinetic hard and soft tissue laser
 Uses specialized fibers of various diameters and lengths to effectively
clean the root canal walls and prepare the canal for obturation

Clinical challanges
 Management of curved canals.
 Management of calcified canals.
 Management of C-shaped canals.
 Management of S-shaped canals.

Management of Curved canals
 First of all estimate the angle of curvature :
To calculate angle of curvature, imagine
a straight line from orifice towards canal
curvature and another line from apex towards
apical portion of the curve
The internal angle formed by interaction of
these lines is
the angle of curvature

 In curved canals, frequently seen problem is
occurrence of uneven cutting.
 File can cut dentine evenly only if it engages dentine
around its entire circumference.
 Once it becomes loose, it will tend to straighten up and
will contact only at certain points along its length.
 These areas are usually outer portion of curve, apical to
the curve, on inner part of curve at the height of curve
and outer or inner curve coronal to the curve.
 All this can lead to formation of ledge, transportation of
foramen, perforation or formation of elbow and zip in a
curved canal

 To avoid : there should be even contact of file to the canal
dentine.
 Can be done by:
1. Decreasing the force by means of which straight files apt
to bend against the curved dentine surface.
2. Decreasing the length of file which is aggressively cutting
at the given span.

Decrease in the Filing Force
Precurving the file:
 Two types : 1) Placing a gradual curve for the entire length of the file 2)
Placing a sharp curve of nearly 45 degrees near the apical end of the
instrument.
Textbook of Endodontics, Nisha Garg 3rd Edn.
Endodontics, Kishor gulabiwala
Once the precurved file is placed in the canal,
there are chances of loosing the direction of
curve.
To avoid
Teardrop shape rubber stopper is usually
recommended with point showing the
direction of the curve.

 Use of flexible files : the restoring force in more flexible files is
naturally lower. Some makes of instrument are more flexible by virtue
of their cross-sectional shape or material of construction, such as
nickel–titanium
 Greater use of smaller files – smaller instruments (size 20
and below) are more flexible and so their use until larger instruments
are able to negotiate without force may reduce adverse dentine
removal.

Use of intermediate sized files
 The transition from one file to the next can also be made
easier by the use of half sizes, e.g. sizes 12, 17, 22, 27 and 32
 This reduces the force required to negotiate the files
apically and also the probability of procedural errors.
“Golden
medium”
intermediate
files
(12, 17, 22, 27,
32, 37)

Reducing or controlling the length or area of file
actively engaged in cutting
 Modified canal preparation techniques
preparing the coronal part of the canal first in a corono-apical or
crown-down approach removes coronal binding and allows more
controlled preparation of the apical part of the canal with the apical
part of the file

 Anticurvature filing
 Denotes filing preferentially away from the inner curve or furcal aspect
of the root canal
 This method, which involves filing the buccal, mesial and lingual walls
of the root canal with more strokes than the furcal wall by a ratio of 3 :
1, is effective.

Modified use of files
 Files may be used in such a way that their area of contact is
reduced.
For example,
1. In the crowndown- pressureless
technique, only the tips of the
instruments are used for cutting.
2. The file is placed in the canal until it
binds and is then rotated twice without
apical pressure to remove dentine at
this binding point.

Management of Calcified Canals
 Calcifications in the root canal system are common
problem.
 Pulpal calcifications are signs of the pathosis, not the
cause.
 Various etiological factors : caries, trauma, drugs and
aging.

Access Preparation of Calcified Canals
 To locate the calcified orifice, first mentally visualize and plan
the normal spatial relationship of the pulp space onto a
radiograph.
 The distance from the occlusal surface to the pulp chamber
is measured from the preoperative radiograph.
 The geometric patterns of canal orifices and their variations
have to be mentally projected on the calcified pulp chamber
floor.

 After this, access preparation is
initiated, toward the assumed
location of pulpal space.
 Accurate radiographic visualization
and intermittent evaluation of bur
penetration and orientation helps
to recognize the calcified orifice

Location of the Canal Orifice
 Significant instrument : DG–16 explorer
 If an orifice is present, firm pressure will
force the instrument slightly into the orifice,
and it will “stick”.
At this suspected point a fine
instrument number 8 or 10 K-file, is
placed into the orifice and an effort
is made to negotiate the canal.
An alternative choice is to use
instruments with reduced flutes,
such as canal pathfinder which can
penetrate even highly calcified
canals.

Penetration and Negotiation of the Calcified Canal
 Once the orifice has been located, a No. 8 K-file is penetrated into the
canal to negotiate the calcified canal , mainly for 2 reasons
1. A No. 10 K-file is too large, and
2. A No. 6 K-file is too weak to apply any firm apical pressure
 Forceful probing of the canal with fine instruments and chelating
agents results in formation of a false canal and continued
instrumentation in a false canal results in perforation.
 Has to be avoided

 In calcified canals, the prognosis of the root canal
treatment depends on the continued health of the
pulp or the periradicular tissues
 In the absence of symptoms or evidence of apical
pathosis, it is clinically practical and satisfactory to
instrument and fill the canal to the level negotiated
followed by recalls.

Guidelines for Negotiating Calcified Canals
 Copious irrigation all times with 2.5 to 5.25 percent NaOCl.
 Always advance instruments slowly in calcified canals.
 Always clean the instrument on withdrawal and inspect before
reinserting it into the canal.
 When a fine instrument reaches the approximate canal length, do not
remove it; rather obtain a radiograph to ascertain the position of the
file.
 Use chelating agents to assist canal penetration.
 Flaring of the canal orifice and enlargement of coronal third of canal
space improves tactile perception

 The use of nickel-titanium rotary orifice penetrating instrumentscan be
used.
 Not anesthetizing the patient while performing access opening can be
useful.
 Patient should be told to indicate when he/she feels a sharp sensation.
 AT that time canals can be located using DG-16 probe.
 Avoid removing large amount of dentin in the hope of finding a canal
orifice.
 Small round burs should be used to create a glide path to the orifice

Guided Endodontic Access for Calcified canals
 3D scan is performed using CBCT.
 All the measurements taken in the CODIAGNOSTIX
software.
 The axis of the drill was angled in such a way that the
tip of the extended drill would reach the
radiographically visible apex of the tooth.
 After planning the position of the drill, a virtual
template was designed applying the template
designer tool.

 The virtual
template was
exported as an
STL file and
send to a 3D
printer

Management of C-shaped Canals
 Though the prevalence of C-shaped canals is low, but
those requiring endodontic treatments present a
diagnostic and treatment difficulties to the clinician.
 Some C-shaped canals are difficult to interpret on
radiographs and often are not identified until an
endodontic access is made.

 Major problems come across during bio-mechanical preparation of C-
shaped canals are
1. Difficulty in removing pulp tissue and necrotic debris,
2. Excessive hemorrhage, and
3. Persistent discomfort during instrumentation
 Continuous circumferential filing along the periphery of the C with
copious amounts of 5.25 percent NaOCl is necessary
 If hemorrhage continues, ultrasonic removal of tissue or placement of
calcium hydroxide between appointments may be used to enhance
tissue removal and control hemorrhage

Management of S-shaped/Bayonet-shaped
Canals
 Pose great problems while endodontic therapy, since they involve at least
two curves
 These double curved canals are usually identified adiographically if they
cross in mesiodistal direction.
 If they traverse in a buccolingual direction, they may be recognized with
multi-angled radiographs,
2nd Curve
1st Curve

 Another method : When the initial apical file is removed from the canal
and it simulates multiple curves.
 Commonly found in maxillary lateral incisors, maxillary canines,
maxillary premolars, and mandibular molars.
 During initial canal penetration, it is essential that there be an
unrestricted approach to the first curve
 For this, the access preparation is flared to allow for a more direct
entry.
 Once the entire canal is negotiated, passive shaping of the coronal
curve is done first.

 Constant recapitulation with small files and copious irrigation is
necessary to prevent blockage and ledging in the apical curve.
 Over curving the apical 3 mm of the file aids in maintaining the
curvature in the apical portion of the canal

TCA technique
 Described by Antonis Chinotis.
 The novel instrumentation approach can be described by the term
Tactile Controlled Activation (TCA).
 Defined as the outstroke activation of an engine-driven file only after it
becomes fully engaged inside a patent canal.
 Utilizes file activation only after maximum engagement of the flutes is
achieved.
 Aims to minimize file engagement during curved canal management
using file activation only when needed

 Starting from the point of maximum engagement around an abrupt
curvature, a passively inserted engine-driven file can be activated by
maintaining apical pressure and moved outwards.
 In this way, tactile feedback from the canal anatomy is maintained
throughout the shaping procedure

References
 Endodontic Practice, Grossman, 13th Edition
 Endodontics, John Ingle, 6th Edition
 Cohen pathways of pulp, 10th Edition
 Common complications in Endodontic, Priyanka Jain
 Endodontic priciples and practices, Mahmoud Torabinjad 4th Edition
 Textbook of Endodontics, Nisha Garg 3rd Edition
 Essentials of Endodontics, Vimal Sikri
 Endodontics, Kishor Gulabiwala
 Charles A. Backman, A Radiographic Comparison of Two Root Canal
Instrumentation Techniques JOE : 18: 1 : 19-24, 1992
 Antonis Chinotis, Root canal treatment of a dilacerated mandibular premolar using
a novel instrumentation approach. A case report International Endodontic Journal,
50, 202–211, 2017
 Wildley et al , A new root canal instrument and instrumentation technique: A
preliminary report OOO :67 : 2 : 198-208 : 1989
 Roane et al. The "Balanced Force" Concept for Instrumentation of Curved Canals JOE
,11::5: 203-2011 , 1985

CLEANING AND SHAPING IN ENDODONTICS

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