This is a presentation which describes in details, the shaping aspect of root canal in root canal therapy. This gives the newer files systems being used

1. Bio mechanical
Preparation
Dr. SURABHI SOUMYA
(2ND YEAR PG)

2. Contents
• Introduction
• History
• Definition
• Concepts
• Criteria for adequate shaping
• Rationale
• Objectives
• Movements of instruments

3. • Serial shaping motions
• Procedural terms
• Basic principles of canal instrumentation
• Different techniques of root canal preparation
• Automated devices (Sonic/ Ultrasonic)
• Procedural errors and manipulation
• Summary & Conclusion

4. Introduction

5. l In most cases peri apical lesions
are associated with the main root
canal systems and form
periapically around the main
foramina.
l The main canal unquestionably has
the highest bacterial load, and
important studies link reduction of
the viable intracanal bacterial load
to favorable outcomes for
endodontic therapy.

6. Therefore a primary aim of all endodontic procedures,
and most notably of cleaning and shaping, is to remove
canal contents, specififically infective microorganisms

7. History
• 1746 - one of the first instruments made specifically for use within
the root canal, (Fauchard). Similar to barbed broach, designed to
remove pulp; without shaping the root canal (pulp space)
• 1852 - Dr. Robert Arthur of Ballimore, described how to make a fine
pulp space file; provided guidelines for its mechanical properties.
• 1915 - Kerr manufacturing Company patented all K-type
instruments.
• 1957 - Richman was first to use ultrasonics in endodonitics.

8. • 1958 - Ingle and Levine first proposed standardization of
endodontic instruments and suggested guidelines for the
same.
• 1976 - The first approved specification for endodontic
instruments American National Standards Institute (ANSI)
specification No. 28, was published.
• Early 1980’s - K-style endodontic instruments came into a
series of modifications with hybrid designs.

9. 1988 - Walia et al first reported the use of Nickel -
titanium alloy for endodontic use.
1989 - Wildey and Senia designed canal master
instruments (Brassler) and a modified version later as
canal master U.
1992 - Herbert Schilder introduces Instruments with
constant 29.17% increase in size (profile 29 series)

10. Mid 1994 - Profile 29 series Greater Taper
instruments were introduced.
1996 - Quantec Series 2000, rotary instruments
(NTCo) made of Nickel Titanium with increases
taper were developed to allow preparation of
suitable tapared canals.
1997 - The tri-auto ZX, which is a Cordless Engine
driven pulp space preparation system, that
electronically monitors the location of file tip and
torque applied to the file, was introduced by J.
Morita U. (Jpn.)

11. Definitions

12. o Bio mechanical preparation: “Controlled removal of the
root canal content and the dentin by careful manipulation of
the root canal instruments and materials”.
oCleaning- removal of all potentially pathogenic contents
from the root canal system before and during shaping.
oShaping- the development of a ‘logical’ cavity preparation
that is specific for the anatomy of each root. Raiden G et al
(JOE) 1998

13. Shaping of Root Canals
PHASE I Negotiating the canal and patency filing
Coronal pre enlargement
PHASE III Working length measurement
PHASE IV Root canal shaping techniques
PHASE V Root canal working width
PHASE II

14. • Instrument ( spreader) try-in (Walton)
• Three size larger than the first file
binds (Grossman)
• Cone fit to the radiographic terminus
(Cohen)
TRY- IN METHOD

15. For apical preparation (Walton) - development
of apical stop or seat
APICAL STOPAPICALSEAT

16. RATIONALE FOR TREATMENT
PULPAL INJURY
ISCHEMIA
INFARCTION
NECROSIS
PERIRADICULAR EXTENSION OF DISEASE
PROCESS

17. OBJECTIVES

18. Biological Objectives:
• Removal of all tissue from the root canal space.
• Confinement of instruments to the roots
themselves.
• No forcing of necrotic debris beyond the
foramen.
• Creation of sufficient space for intra-canal
medicaments.

19. Mechanical Objectives
(Schilder):
• Continuously tapering funnel
from the apex to the access
cavity.
• Cross-sectional diameter should
be narrower at every point
apically.
Continuous taper

20. • The root canal preparation should flow with
the shape of the original canal.
• The apical foramen should remain in its
original position.
• The apical opening should be kept as small as
practical

22. v Preparation must enlarge the canal while
maintaining the general form of the
preoperative shape, but it also must develop
the most desirable shape to fill
v Once working length is determined all
instruments should be kept within the confines
the canal.
v Canals must be prepared in wet environment

23. Different movements
of Instruments

24. • Filing / rasping: this terms
refers to push and pull action
with instruments.
• Reaming: Indicates the
clockwise / right hand rotation
of instrument.

25. • Combination of reaming and filing: File is inserted
with ¼ CW rotation and inwardly directed pressure
(reaming) followed by subsequent withdrawal (filing).
• Schielder’s modification : Clockwise rotation of half
revolution and then directing the instrument apically.

26. • Balance Force Technique : Involves the
oscillation of files right and left with different
arches in either direction.

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

28. • Watch winding and pull- The file (H-file) inserted
with right and left back and forth motion (rocking) until
it meet resistance. Then file must be freed by pull
stroke.

29. Serial Shaping Motions

30. • Follow: is usually performed with files. They
are used during initial cleaning and shaping.
• Follow- withdrawal: It is a simple in and out
passive motion performed with file.
• Cart: Extension of reamer to or near the
radiographic terminus
• Carve: Shaping of the canal using a reamer

31. • Smooth: It refers to finishing the preparation with files.
It is usually performed with circumferential filing
motion.
• Patency: Refers to cleaning the portal of exit of root
canal with small size instruments.
• Scouting: It is estimating the gauge and anatomy of root
canal with help of instrument.

32. • Gauging: Knowing the cross sectional
diameter of the foramen that is confirmed by
the size of the instruments that fits snugly at
working length.
• Tuning: It is ensuring that each sequentially
larger instrument uniformly backs out of
canal by 0.5mm.

33. Procedural Terms
• Initial apical file- the smallest or the first file
that binds at correct working
length
• Master apical file- the largest file that binds
slightly at correct working
length after straight line
access

34. • Circumferential filing (Lim & Stock)- instrument is first
moved toward buccal side of the canal, then reinserted
and moved mesially. This continues around the
preparation to the lingual aspect and then to distal until
all walls have been rasped.

35. • Recapitulation- returning to a smaller
instrument from time to time before
advancing to a larger size,to prevent packing
of the dentinal tubules and to ensure
patency of the canal

36. • Anticurvature filing (Abou- Rass et al)-
filing preferentially away from the inner
curve or furcal aspect (danger zone)

37. BASIC PRINCIPLES OF CANAL
INSTRUMENTATION (Weine)

38. • Rubber dam isolation
• Straight line access to the apical foramen
• Files are always worked in wet environment
• Preparation of canal should be completed while
retaining its original form and the shape
• Exploration of the orifice is always done with smaller
file to gauge the canal size and the configuration

39. • Canal enlargement should be done by using
instruments in sequential order without skipping
sizes.
• All the working instruments should be kept in
confines of the root canal to avoid any procedural
errors.
• Instruments binding or dentin removal on insertion
should be avoided.
• After each insertion and removal of the file, it’s
flute should be cleaned and inspected.

40. • Smaller number of instruments should be used extravagantly.
• Recapitulation is regularly done to loosen debris by returning
to working length. The canal walls should not be enlarged
during recapitulation.
• Over preparation and too aggressive over enlargement of the
curved canals should be avoided.
• Never force the instrument into the canal to prevent its
breakage.

41. Techniques for preparing
root canals
Modifications:
• Crown down pressure less
• Balance force technique
• Double flare technque

42. APICAL- CORONAL
TECHNIQUES

43. Standardized Technique
• First formal root canal preparation technique
• Introduced by Ingle
• Canal is prepared by enlarging it sequentially
to selected size

44. WL determined Select the initial apical file
Circumferential filing to increase the apical
Constriction 2-3 files sizes greater than the
Initial apical file

45. • Advantages
o easy to master
o preparation has the
same shape, size and
taper as a
standardized
instruments
o less time consuming
• Disadvantages
oLoss of working
length due to
accumulation of
dentin people debris
oIncreased incidence
of procedural errors
o designed for single
cone filling
technique

46. Stepback Preparation( Telescopic/
Flare/ Serial Root Canal Preparation)
• Weine, Martin, Walton and Mullaney were early advocates of
step back technique.
• However, this method has been well described by Mullaney in
1960
• Emphasizes on keeping the apical preparation small, in its
original position and producing a gradual taper coronally.
• Canal preparation in two phases:
• Phase I – preparation of apical constriction
• Phase II – preparation of the remaining canal

49. • Advantages:
o More flare at coronal
part of root canal
with proper apical
stop
o less likely to cause
peri apical trauma
o develops apical stop
preventing overfilling
• Disadvantages:
o Difficult of irrigate
apical regions
o More chances of
pushing debris
periodically
o Time consuming
o Increased chances of
iatrogenic errors
o Difficult to penetrate
instruments inside the
canals.

50. • How much is the Stepping back distance?
- 1mm – Stock
- 0.5mm - Walton
• How many step backs?
- up to straight midcanal portion (Ingle)
- up to at least # 60 or # 70 no. instrument (Walton)

51. Modifications of step back
technique:
• Schilder – advocated canal bed enlargement.
After apical prep, the next larger instrument is
placed into the canal to the point of initial
contact and rotated for one half turn. The
process is repeated with increasingly larger
istruments with simultaneous irrigation b/w
each files.
• Weine – Pre curving of files to reduce the
chances of alteration of the original canal
anatomy.

52. Passive step-back preparation
(Triple 0,1994)
- Torabinejad in 1994.
- It is a combination of hand and rotary instruments to
attain an adequate coronal flare before apical root canal
preparation.
Technique:
Ø15 K file used to establish the W.L.
Ø15 K using very light pressure with 1/8 to ¼ turn and
push and pull strokes is used to establish apical patency.

53. Ø20-40 k files are inserted into the canal
passively ( removes debris and creates mildly
flared prep for insertion of GG drills)
ØCopious irrigation is done frequently with
hypo.
Ø After this, no.2 GG drills is inserted into
mildly flared canals to a point where it binds
slightly (pulled back 1-1.5 mm and then
activated). In a similar fashion, no.3 and 4 GG
are used coronally.

54. • 20 k file is inserted up to the W.L, and the
canal is then prepared with sequential use of
progressively larger instruments placed
successively short of the W.L
• Advantages:
• Provides significantly cleaner canals
• Less chances of procedural errors
• Ease of clinical application
• Applicable in every canal type
• Can also be used with ultra sonic instruments

55. Modified step-back:
• Here after apical preparation the step back
procedures begins 2-3mm up the canal.
• Gives short, almost parallel retention form to
receive primary GP which shows slight tuck back,
when it is removed.
• Advantages:
• Less chances of apical transportation
• Increases the chances of canal walls being planed.

56. • Disadvantages:
• Less space for irrigants leads to accumulation
of debris in the canal
• Chances of loss of working length
• May result in procedural errors like ledge
formation.

57. Progressive Enlargement
Technique (JOE, 1992)
• Type of step back preparation
• Advocated by Backman et al
• Three phases- apical preparation
- progressive filing
- coronal 2/3rd filing
• All instrumentation using K-file and H-file
• Uses stem winding motion

58. • Advantages-
- can be used in small curved canals
- original apical root canal curvature
maintained

59. Balanced force technique
(Roane and Sabala 1985)
“Positioning and preloading an instrument
through a CW rotation and then shaping the
canal with a CCW rotation”

60. Flex- R- file (Moyco Union
Broach)
• Machined from the blank of
triangular cross-section
• Lacks sharp transition
angles
• Increased stiffness and
strength in smaller sizes
and increased flexibility in
larger sizes
• Safe ended tip
• Maximum efficiency in CCW
rotary motion

61. PHASE I - Placement Phase
PHASE II - Cutting Phase
PHASE III - Removal Phase

62. PLACEMENT CUTTING REMOVAL

63. WL determined Enlarge the canal to
size 25 to full WL
Size 30 & 35, 0.5mm
short of WL

64. Size 40, 1mm short
of WL
Size 45, 1mm short
of WL
Gates Glidden size 2-6 to
complete the complete flare

65. • Advantages:
• This technique balance and
maintains the file central
even in curved canal.
• Better control of the file
• Allows selective cutting
• It avoids transportations
• Disadvantage:
• Wide preparation, may
lead to perforation
• Instrument prone to
fracture
• Improved tactile sense
required to control the
instrument

66. CORONAL APICAL
TECHNIQUES
“ coronal portion of the canal is
prepared first before determining the
working length.”

67. Step-down preparation (Schilder
1974)
• Goerig, (JOE 1982) named and described the
technique in detail.
• Also called as crown down technique
• Coronal aspect of the root canal prepared and
cleaned before the apical part.

68. 16-18mm coronal
part of canal
prepared with H-file
Coronal flare prepared
With GG 123
WL determined.
Use larger files for
Coronal prep
Prepare apical portion
by step back
GG 3 extending 3-4mm

69. • Advantages:
• Straighter Access
• Early Debridement
• Better and deeper
penetration of irrigant
• Better control over
apical instrumentation
• Reduces ‘piston in a
cylinder effect’
• Disadvantages:
• Apical blockage
• Formation of Ledges
• Perforations

70. ØRotary files used in crown down technique:
• Profile
• Profile GT
• Quantec
• Light speed
• Protaper
• Race
• Hero 642

71. Double Flare technique
(Fava)
• Indication:
• For straight canals
• Straight portion of curved canals.
• Contraindication
• Calcified canals
• Young permanent teeth
• Teeth with open apices

72. WL determined Introduce larger file (35) about
14mm coronal portion of the
canal
File with no. 30, 1mm deeper
than size 35
Continue deeper till WL reached
with smaller file

73. .
File with size 10 to 1mm
deeper than size 15 (# 10 now
at WL)
Prepare the canal till size
25 at full WL
Prepare apical portion
of canal by step back
preparation

74. Crown Down Pressureless
Technique
• Introduced by Marshall & Pappin
• Described by Morgan & Montgomery (JOE,1984)
• Facilitate preparation in curved canals without
causing the deviation.
• Rotary action is used to cut dentin

75. Determine
radicular access
Widen 16mm of
coronal portion of
canal till 35 no.
Prepare the canal
with 30 no. file
without apical force
Prepare the canal with
10 no. file without
apical force

76. Repeat the
sequence starting
with size 40
Prepare the canal
15 no. file at full
WL
Repeat the
sequence with 45
Prepare the canal
20 no. file at full
WL

77. Repeat the sequence
starting with size 50
Prepare the canal
25 no. file at full WL

78. • Advantages
• Less extrusion of debris
• Effective in maintaining canal shape
• Less chance of alteration of working length

79. Canal Master Technique
(Triple O, 1989)
• Introduced by Wildey and Senia
• Uses Canal Master instrument (SW Instrument):
- cutting portion reduced to 1-2mm with
0.75mm non cutting pilot tip
- the cutting portion resembles reamer with
blunted edges
- rest of the instrument is parallel sided
shank of round cross section
- maximum efficiency with CW rotary motion

80. • Canal Master (SW)
instrument
• Hand files-20-80
• Rotary files -50-100

81. WL determined
Prepare the beginning of
the curve using canal
master-U (size 50)
Size 80 instrument to
beginning of curve
Prepare the canal
with size 20 to full
WL (up to # 50 )

82. Prepare the canal with
size 50 to full WL
Size 55 1mm shorter
than WL
Size 60 2mm shorter
than WL
Size 80 4mm shorter
than WL

83. Advantages
• Prevents transportation of the canal
• Small cutting head provides minimum cutting
surface with maximum control
• Increased flexibility
• Instrument stays centre in the canal
• It gives finer tactile perception
• Does not require recapitulation

84. Modified Double Flare technique
(JOE, 1992)
• Advocated by Saunders & Saunders
• Uses non cutting tipped instruments with step
back technique
• Preparation starts in the coronal part of the
canal

85. # 40 Flex R file with balance force introduced in the
straight part of the canal
Sequentially larger sizes used to inst. straight part
Coronal 4-5mm inst. with GG (2 and 3)
# 20 file extended to WL. Canal prepared sequentially
with BF tech

86. Preparation continued until clean dentin shaving
obtained
MAF varies between # 40-45 file
Step back with Balanced force done to prepare
remaining curved portion

87. Anatomic Endodontic
Technology

88. Special anatomical problems in
canal cleaning & shaping
• Management of curved canals:
1)Precurving of instruments:
• Easy insertion
• Prevent ledging.
• Pre-curving can be done by grasping with a gauge sponge
and carefully bending with the blades of files until desired
curvature is attained.

89. COMMERCIAL DEVICES
Endo bender plier( Sybron endo)

90. 2) Extravagant use of smaller number files
3) Use of intermediate size of files
4) Use of flexible files
5) Anticurvature filing
6) Changing the canal preparation technique

91. • Anticurvature filling

92. • Double / Bayonet shaped canal:
• Firstly, the optimal nature of the canal
is to be determined ( specially if there
is bucco lingual curvature)
• Negotiate the entire canal
• Introduce small H-file to junction of
middle and apical third of canal and file
the inner portion of curve.
• Copious irrigation and recapitulation
• Precurving the instruments helps in easy
instrumentation

93. Dilacerated canal:
• Enlarge the cervical and
middle third of canal first.
• Introduce small H-file to
beginning of the curve and
do circumferential filing.
• Prepare the canal using
No.15 file by dulling its
outer portion in apical third
and inner portion in middle
third of instrument.

94. • Reverse flaring / pre-flaring:
ØCoronal portion of the root canal flared before the
completion of apical portion.
• Advantage:
o Effective penetration of irrigants
o Better instrumentation in apical area
o Plugger and filling materials penetrate to
the apex more easily

95. • Extremely narrow canals:
o By using smaller instruments along with chemical
chelators.
• C – shaped canals:
o Major problems encountered during BMP of C – shape
canals are the difficulty in removing the pulp tissues
and necrotic debris, excessive bleeding and persistent
discomfort during instrumentation
o Continuous circumferential filing along the periphery
of the C with amount of hypo is necessary
o Ultrasonic removal of tissues if the bleeding is
persistent or placement of Ca(OH)2 in b/w
appointments.

96. • Calcified canals:
vSteps-
ØAccess opening followed
by orifice location using
DG-16 explorer
ØPenetration and
negotiation of canal
orifice using 8K file, pre
curving in cases of curved
canals

98. Non instrumentation technique
(Lussi)
• Controlled cavitation and hydrodynamic turbulence
in the root canal
• Alternating pressure fields are generated with an
overall reduced pressure range

99. Procedure
• First reduced pressure at -0.7 bar generated,
producing macroscopic and microscopic voids (5-50µm).
• This is followed by a quick pressure rise to -0.1 bar
leading to collapse of the bubbles thus building up
cavitation and turbulence
• This allows the irrigant (NaOCl 3%) to penetrate the
whole root canal system.

100. • Frequency used is 25 Hz,
• Low frequency allows bubbles to grow more
• Smooth exchange of irrigant is obtained using
double tubing

101. Double tubing

103. vAdvantages:
• Cleaning of the canal similar
or better than with hand
instrumentation.
• Better results in curved
canals
• Less chances of passing of
the irrigant beyond the apex
(as reduced pressure is used)
• Treatment duration is
independent of the number
of root canals in the tooth
vDisadvantages:
• Does not shape the canal
• Tooth has to be insulated

104. Automated Devices
• Classified according to the type of movement
imparted to the cutting instrument (Stock)
• Rotary-
- used in a slow running standard handpiece
- 16:1 gear reduction handpiece (NiTiMatic)
runs at 300 rpm
- Gates Glidden, Pesso and Canal Master

105. 16:1 gear reduction unit
with handpiece

106. • Reciprocal quarter turn:
- uses special handpiece- Giromatic
- Instrument activated by 90° reciprocate arc
- works at a speed of up to 1000cycles/min

107. Giromatic handpiece
Reciprocal quarter turn

108. - Instruments that can be used with this
handpiece are-
Giro pointer (16mm long orifice opener)
Giro broach
Giro file ( H -configuration)
Giro reamer
Heli giro file (three cutting blades in
cross section)
Giro reamer Giro files

109. - Disadvantages
• Clogging of the canal
• Tendency to create ledges and flaring in apex
• Less effective compare to hand instrument
(Grossman)
• Difficult to use in narrow canals.

110. • Racer contra angle handpiece
- uses standard file with oscillation in the canal
- instrument length can be adjusted to the WL
• Disadvantage:
- clogging of the canal
- push debris into periapical region

111. • Vertical:
- Canal Finder system
- vertical movement of .3-1.0mm
- free rotational movement
Vertical movement with free
rotation

112. • Canal Leader system
- modified speed reducing handpiece with 4:1 step
down
- vertical movement of 0.4-0.8mm
- has 30◦ contra- rotational movement
- used with three types of instruments
- safe ended K-file (narrow canals)
- H-files
- flexible H-files (safe ended)

113. • Random:
- Excalibur handpiece-
-random lateral movements
- runs at 20000- 25000 rpm
- uses modified K-files
Disadvantage-
- bulky handpiece, Random movement
(Excalibur)

114. Ultrasonic Oscillation
Instruments
• Richman in 1957 introduced ultrasonics in Endodontics
• The machines used for this purpose transmit low frequency
ultra sonic vibrations by conversion of electro magnetic
energy to mechanical energy to produce oscillation of files
• Frequency of oscillation = 20,000 - 25,000 vib/sec
• During oscillation of the file, there is continuous flow of irrigants
solutions from the hand piece along the file which causes
cavitation
• Another effect is acoustic streaming which is produced around an
object oscillating in a liquid
• A/2 Ahmed 1987, most of the benefits of ultra sonic are due to
acoustic streaming rather than cavitation

115. • Technique:
ØBefore starting, canal should be prepared to
at least size 15 K file
ØAfter activation, ultrasonic file is moved in a
circumferential manner with push-pull stroke
along the walls of the canal
ØFile is activated for one minute.
ØThis procedure is repeated till the apex is
prepared to at least size 25

117. • Advantages
• Better cleaning
• Enhanced chemical and
anti-bacterial action of
irrigant
• Disadvantage
- apical third of the canal
needs to be hand
instrumented
- may generate fine mist of
NaOCl, a health hazard

118. Sonic Oscillation
• Operate at 1500-6500 cycles
/min.
• Prepare the canal by push & pull
and circumferential strokes.
• Uses water as an irrigant
• Rispi file (coronal 2/3rd of canal)
• Heli-sonic file, Shapers – For
apical 1/3rd
RISPI FILE

119. Endosonic handpiece with file Push & pull Circumferential

120. Cleaning enhanced by
acoustic micro-streaming
with two areas of
turbulence
- One at mid shank
- one at tip of the
instrument.
AT MID SHANK
AT THE TIP
Acoustic Micro-streaming

121. LASERS
• Weichman and Johnson (1971)
• Initially Nd:YAG, CO2 laser.
• Recently: Argon laser, excimer laser, holmium
laser, YAG laser with various wavelength are
tried.

122. • Action: by melting the dentin surface and
vaporization of debris and pulpal tissue
remnants.
• Indications
- Straight / slightly curved root canals
- Wide root canals

123. Fiber optic tip
Fiber optic tip
inside the root
canal

124. Procedure
• Working length determined
• Enlarge apical region with #15 file
• Begin preparation with laser energy at 1500 milli joules.
• Fiber optic inserted to working length and moved
circumferentially first apically and then coronally to
enlarge upto #60 file.
• Four exposures of 15 seconds are made.
• Recently ArF excimer at 193nm, Er:YAG laser are used.

125. • Advantages:
• Reduce the microbial
load
• Reduce inflammation
• Better patent
compliance
• Disadvantages:
• Acc to Bahcall et al
1992, heat produced
may damage
surrounding tissues
i.e bone and pdl

128. Procedural errors

129. Ledging

130. Breakage of instruments in
the canal

131. Classification of damage of
instruments

132. Zipping

133. Conclusion
“ Cleaning and Shaping is a game and, as such, can be
played at various skill levels. Visualizing and executing
great play can move the clinician towards mastery and
winning the inner game of endodontics.”
- Ruddle

134. References
• Grossman 11th edition
• Cohen 8th and 6th edition
• Ingle 5th edition
• Stock 2nd edition
• Walton
• Weine 5th edition
• DCNA, 1984
• JOE, 1992
• JOE, 1991
• JOE,1993
• TRIPLE O, 1994
• BDJ, 2004