Rotary Endodontic Instruments

Guided by:
Dr Hemant Vagarali
Presented by:
Dr Sahana Umesh

CONTENTS
 Introduction
 History
 Classification of endodontic instruments
 Why rotary instrumentation?
 Steel Rotary Instruments
 Characteristics Of NiTi Alloy
• Shape memory
• Super elasticity
• Strength
 Metallurgy of Nickel Titanium alloys

 Advances in NiTi alloy
 Functioning of NiTi Rotary instruments
• Torsional stresses and fatigue
• Bending stresses
 Importance of the Section of the NiTi Rotary Instrument
 Endodontic Motors
 Life of Rotary NiTi Instrument
 NiTi rotary systems
• ProFile
• Hero
• K3

• ProTaper
• GT files
• FlexMaster
• RaCe
• Quantec
 Recent NiTi systems
• ProTaper Next
• One Shape
• WaveOne
• XP Endo Shaper
• TruNatomy

 Iatrogenic Mishaps and Safety
• Fracture of instruments
• Ledging
• Apical blockage
• Over-instrumentation
• Apical extrusion of debris
• Development of dentinal cracks
• Heat damage
• Perforation
 Conclusion
 References

 Instruments play a very important role in the
success of a root canal treatment therefore a basic
knowledge of endodontic instruments is essential.
 Various endodontic instruments are used for
cleaning and shaping of the root canal system,
which ultimately determines the clinical outcome.
 Rotary systems have proved to be safer, quicker
and more efficient over the conventional
instruments.
INTRODUCTION

 1733 - “Le chirurgien dentiste,” Pierre Fauchard
described instruments for root canal preparation.
 The basic treatment technique at that time was
cauterization of the pulp with heated instruments.
 1838 - Edward Maynard - development of the first
endodontic hand instrument.
 The first description of the use of rotary devices -
Oltramare.
HISTORY

 1889 - William H. Rollins developed the first
endodontic handpiece for automated root canal
preparation.
 This endodontic handpiece rotates at low speed of
approximately 100 rpm and with a 360° rotation,
similar to the motors used today for canal preparation
with NiTi instruments.

 1928 - ‘Cursor filing contra-
angle’ was developed by the
Austrian company
W&H(combined rotational and
vertical motion of the file).
 1958 – Racer handpiece (In
1958 W&H company start
Marketing The Racer-hand
piece in Europe and worked
with a vertical file motion.)

 1964 - Giromatic handpiece (a
reciprocal 90º rotation).
 1984 - Canal Finder was the first
endodontic handpiece with a
partially flexible motion.
 1957 - Richman introduced
Ultrasonics and sonics systems.
 Martin and Cunningham made
ultrasonic devices popular in the
1970s.

 First ultrasonic device was marketed in 1980.
 First sonic device in 1984.
 Electrosurgical devices and non-instrumental technique
(NIT) by Lussi, using a vacuum pump for cleaning and
filling of root canals seemed to be promising.
 The NIT was designed to clean the root canal system
with intermitted positive and negative pressure and
without any instrumentation or removal of root dentin.
 These techniques did not gain popularity or broader
acceptance despite the innovative ideas.

 1988 - Instruments made from nickel-titanium (NiTi)
were first described.
 Motors with a 360° rotation or with a reciprocal
motion became popular again, making the use of
NiTi more efficient.
 2010 - SAF system was introduced.

GROUP I
Hand-
operated
Barbed
broaches
and rasps
K-type
reamers and
files
Hedstroem
files
GROUP II
Low speed
SS
instruments
Gates-
Glidden
drills
Peeso
reamers
GROUP III
Sonics &
Ultrasonics
GROUP IV
Engine
driven NiTi
instruments
Rotary
Reciprocating
Canal
adaptive
CLASSIFICATION OF ENDODONTIC INSTRUMENTS
- Grossman’s Endodontic Practice 14th ed

 Enhanced ability to collect and remove debris from the
canal system.
 Better control for maintaining the central axis of the
canal, reducing the incidence of ledging or
perforating.
 Reduction in the time required for instrumenting the
canal.
WHY ROTARY INSTRUMENTATION?

The most commonly used low-speed rotary stainless
steel instruments in endodontics are as follows:
1. Gates-Glidden drills
2. Flexogates
3. Largo drills / Peeso Reamers
4. LAAxxess burs
5. Endo-Eze A.E.T. files
ROTARY INSTRUMENTS

 Characterized by a long shank and
an elliptical extremity which is
flame shaped with a “guiding” non
cutting tip.
 Available in six sizes.
 Marked with circular notches on
the part that attaches to the contra
angled handpiece.
 Gates Burs is measured at the
widest part of their elliptical
portion
GATES GLIDDEN DRILLS

 Gates drills are available
• short version ~ overall length - 28 mm (shank
length + active part of 15 mm)
• long version ~ overall length of 32 mm (shank
length + active part of 19 mm)
 Gates-Glidden drills are designed with the weakest
point at the start of the shank

 Recommended speed – 800 rpm
 Gates # 1 and # 2 are very fragile and can
fracture at the level of the tip, especially if
the recommended rotational speed is
exceeded and when they are subjected to
bending stress.
 The blades of the Gates-Glidden drills do
not have angles but flat cutting planes to
reduce the aggressiveness and the tendency
to screw in.
 They could be considered as the first
example of the “radial lands” type of
blades

 The Gates drills must be used
passively on withdrawal from the
canal with a brush like
circumferential movement
 Should always be preceded by
preflaring of the canal using hand
instruments
 Active use of the Gates Glidden
drills is not recommended because
they can lead to the formation of
ledges and dangerous structural
weakening that in the curved and
thin canals can cause stripping.

 Uses of Gates-Glidden drills:
• Enlarge root canal orifices
• For coronal flaring during root
canal preparation
• For removal of lingual shoulder
during access preparation of
anterior teeth
• During retreatment cases or post-
space preparation for removal of
gutta-percha
• During instrument removal, for
space preparation

 Drux burs are designed similarly to the Gates-
Glidden (GG) drill, but have a flexible shaft.

 Flexogates are modified Gates - Gliddens.
 They are made up of NiTi and have noncutting tip.
 They are more flexible and used for apical
preparation.
 Flexogates can rotate continuously in a handpiece
through 360°
 These instruments have many advantages over the
traditional instruments in that they allow increased
debris removal because of continuous rotation,
smoother and faster canal preparation with less
clinician fatigue.
FLEXOGATES

 Largo drills or Peeso Reamers are steel instruments similar
to the Gates-Glidden drills but differ in that the blades are
spread over a wider surface and the shape is cylindrical.
 They should be used in brushing motion.
 Very useful in the preparation of the dowel space (post
space) in canals already enlarged or in retreatments to speed
up the removal of the obturation material.
LARGO DRILLS / PEESO REAMERS

 Designed by Dr. L.S. Buchanan
 Specifically designed to eliminate interferences in the pulp
chamber and coronal one third of the canal.
 Available in 3 diameters:
1. Small – min. diameter of 0.20 mm
2. Medium – min. diameter of 0.35 mm
3. Large – min. diameter of 0.45 mm
LAAXXESS BURS

 LAAxxess burs have a
• rounded guiding tip
• 12 mm length of flutes
• first 3 mm has a parabolic
increase
• remaining 9 mm is
characterized by a .06
taper

 The particular design of this bur favors the
penetration of the coronal one third of the canal
while the blade with its double cutting spiral rapidly
removes the pulp chamber and coronal interferences.
 Recommended rotational speed - 5,000 rpm.

 Designed by F. Riitano.
 The Endo-Eze A.E.T. Files
(Anatomical Endodontic Technology)
consist of two types of instruments,
the Shaping Files and the Apical Files
 Shaping Files – used with contra
angled handpiece having alternate
clockwise/counter-clockwise
movement of 30°
ENDO - EZE A.E.T FILES

 Available in 4 lengths (19, 23, 27 and 30 mm)
• Shaping 1 ~ tip diameter of 0.10 mm and .025 taper
• Shaping 2 ~ tip diameter of 0.13 mm and .045 taper
• Shaping 3 ~ tip diameter 0.13 mm and .06 taper
• Shaper C ~ tip diameter 0.25 mm and taper .035
 Shaping Files have blades that cut even with a
lateral brushing movement
 Particularly indicated for the cleaning of canals with
an irregular anatomy such as canals with an
elliptical cross-section, C-Shaped etc.

 Apical Files are hand instruments in steel
characterized by a working part with limited length
to allow a better tactile perception during the apical
shaping.
 Apical Files are available in lengths of 19, 23, 27
and 30 mm and ISO diameters of 15 to 50.
 Taper of the working part is .02 up to diameter 25
and then increases to .025

 NiTi alloy – W. H. Buehler (1960s)
 NiTiNOL – Nickel Titanium Naval Ordinance Laboratory
 Introduced into dentistry - Andreasen et al. (1971) -
orthodontic wires.
 1975 – Civjan & associates – 55-Nitinol (55% Ni by wt.);
60-Nitinol (60% Ni by wt.)
 They found that 60-Nitinol is corrosion resistant hence
can be used for hand and rotary cutting instruments or
files for operative dentistry, surgery, periodontics &
endodontics.
HISTORY OF NITI ALLOY

 1988 - First potential use in endodontics – Walia &
associates.
 1992 – Serene introduced new NiTi files to students
in College of Dental Medicine at Medical University
of South Carolina.
No. 15
SS files
2-3 times
elastic
flexibility
Superior
resistance to
torsional
fracture
No. 15
NiTi
files

Shape Memory:
 By shape memory we mean the capacity of NiTi
alloys to reacquire its initial shape through heating
after strain.
 This property is utilized in orthodontics but not in
endodontics.
CHARACTERISTICS OF NITI ALLOY

Superelasticity:
 Elasticity – Property of bodies to deform by the action
of external forces and once these external forces cease
the ability to return to its original state.
 Elastic limit – Limit beyond which there is a
component of plastic strain which can no longer be
recouped by the elimination of external forces.

 The stainless steel endodontic instrument presents a
higher stiffness while the NiTi instrument is
particularly compliant.
 The use of endodontic instruments in NiTi is
particularly advantageous for shaping the canal
system in harmony with the original anatomy

Strength:
 Walia et al. and Camps et al. have demonstrated that
files in NiTi were much more resistant to clockwise
and counter-clockwise torsional stress compared with
files of equal size but in stainless steel.
 This elevated strength of the NiTi alloy has made it
possible to manufacture rotary instruments that have
greatly simplified the shaping of the root canal
system.

 The NiTi alloy used in root canal treatment contains
approximately 56% (in wt) of Nickel and 44% (in wt) of
Titanium.
 In some NiTi alloys, a small percentage (<2% in weight)
of Ni can be substituted by cobalt.
 The resultant combination is a one-to-one atomic ratio
(equiatomic) of the major components (Ni:Ti).
 This alloy has proved to be among the most biocompatible
materials and it is extremely resistant to corrosion
METALLURGY OF NiTi ALLOYS

 NiTi belongs to the family of inter-metallic alloys.
 This means that NiTi alloy can exist in various
crystallographic forms, with distinct phases and
different mechanical properties:
• Austenitic phase
• Transformation phase
• Martensitic phase

1. AUSTENITIC PHASE (A): with body- centered cubic
lattice. It’s the most stable phase.
2. MARTENSITIC PHASE (M): with hexagonal
compact lattice. It’s the most unstable and ductile
phase.
3. TRANSFORMATION PHASE (T): made up of series
of intermediate phases which transform one into the
other, causing a movement of the Ni and Ti atoms onto
opposite and parallel crystalline levels; this doesn’t
entail a variation of the crystallographic shape.

 Each crystalline phase exists in a specific temperature
interval.
 The transition from one phase to the other is possible
only within a temperature range including those at the
beginning and at the end of transformation.

Austenitic
phase
Martensitic
phase
T.T.R

 Such phase changes can also be induced by the
application of deformation states, as it happens with
NiTi endodontic instruments during their work
inside the root canals
 NiTi alloys are characterized by a stress- distortion
diagram which is divided into three distinct portions

Aim of this study: To compare the effect of hand instruments and rotary
nickel titanium on the extent of straightening of curved root canals.
Preoperative and postoperative radiographs were taken of each tooth
using customized bite blocks
Conclusion: This clinical study indicates that FlexMaster(NiTi)
instruments prepared curved canals more rapidly and with only minimal
straightening compared to hand staninless steel instruments

1. M-wire NiTi - Developed by Dentsply Tulsa Dental Specialties
(Tulsa, OK, USA)
Advantage: This material has greater flexibility and an
increased resistance to cyclic fatigue when compared to
traditional NiTi alloys
2. R-phase NiTi – Developed by SybronEndo (Orange, CA, USA)
Advantage: Files have reduced stiffness and more fracture
resistance compared to standard NiTi files.
3. Controlled-Memory (CM) NiTi
Advantage: Files have superior cyclic fatigue resistance and
increased torque strength over traditional NiTi files.
ADVANCES IN NiTi ALLOYS

 Its important to know the functioning of the NiTi
rotary instruments during the shaping of the canal
system.
 The states of stress to which the NiTi rotary
instrument is cyclically subjected are responsible for
the strain (deterioration).
 The strain is determined by two principal types of
stresses: bending stress and torsional stress.
FUNCTIONING OF NiTi
ROTARY INSTRUMENTS

Torsional stress
 Torsional stresses of elevated intensity rapidly causes
fracture of the instrument.
 It happens in three situations:
1) when a large surface of the instrument rubs excessively
against the canal walls (taper lock)
2) when the instrument tip is larger than the canal section
to be shaped
3) when the operator exerts excessive pressure on the
handpiece

Large contact surface
 The larger the blade-dentine contact surface the
higher the torque required to allow the rotation of the
instrument and therefore the cutting of the dentine
 An elevated torsional stress is stored in the alloy,
rapidly reducing the life of the instrument
 If the torque values necessary to make the instrument
rotate exceed the values of the maximum torque
moment that the instrument can endure, the instrument
distorts and fractures

 To avoid these limitations, NiTi rotary
instruments with greater taper must be
utilized with the crown-down
technique.
 Blum et al. have demonstrated that the
NiTi rotary instruments are subjected to
lower stress levels if utilized with the
crown-down technique rather than if
utilized with the step-back technique.
 Cutting ability of the instrument is also
more efficient with the crown-down
technique.

 Accumulation of dentinal debris between the blades of
the instrument can increase the surface contact
between canal wall and instrument thereby increasing
the torsional stress.
 The operator must become aware of when the speed
with which the NiTi rotary instrument advances inside
the canal starts to diminish, this is a sign of an
excessive accumulation of debris between the blades.
 Hence its important to clean the blades after every
passage into the canal.

Instrument tip and canal width
 Vast majority of rotary NiTi instruments with greater taper
have a non cutting / moderately cutting tip.
 This is to prevent the formation of ledges, false paths or
apical foramen transport.

 If these tips encounters a canal or a canal portion
with a smaller cross-section, the tip advances with
great difficulty.
 Torsional stress increases enormously and if the tip
binds and the gearing of the motor is higher than the
maximum torque that the instrument can withstand, it
immediately undergoes plastic strain and fractures.
 Essential to manually create a glide path for the tip of
the greater taper NiTi rotary instrument that will have
to be utilized in complex canals.

Conclusion:
The manual pre-flaring avoided subjecting the tip of the S1 to torsion
while trying to make a path in a canal with a very small cross-section.
In this way one created a guide path for the tip of the NiTi rotary
instrument thereby enormously reducing the torsional stress that the
instrument experiences and in so doing increases its life span six fold.

Excessive manual pressure on the handpiece
 An excessive manual pressure on the handpiece
causes a notable increase in the friction between the
instrument and the canal wall.
 Consequently very high torsional stresses are
generated which could immediately cause the
fracture of the instrument.

Bending stresses
 These are the main causes of strain and they depend
on the original anatomy of the canal which forces the
instrument to bend as it passes through it.
 Pruett et al. have demonstrated that the curve radius,
the bend angle and the largeness of the instrument
are the factors responsible for the fractures due to
bending fatigue.
 If one imagines a stationary rotary instrument inside
a curved canal it follows that it will be subjected to
two different types of stresses:

– compression stress on the internal surface of the curve
– tensile stress on the external surfaces of the curve.
• There will be continuous passing
from tension to compression,
from compression to tension and
so on.
• Hence the alloy will be
continuously subjected to stress
of the opposite type.
• Therefore it is important to
never stop inside a curved canal
with the instrument in motion.

IMPORTANCE OF THE SECTION OF
THE NiTi ROTARY INSTRUMENT
 The ideal NiTi rotary instrument should be sufficiently
compliant to be able to create a centrifugal shaping of the
canal and to be sufficiently resistant to withstand the
torsional and bending stresses.
 The ability to cut the dentine is determined by the shape
of the blade.
 Berutti et al. have analyzed the mechanical behaviors of
two sections, the ProFile (U File) and the ProTaper
(convex triangular section) through the method of finite
element analysis.

 The distribution of torsion stresses in ProTaper section
were regular and uniform, while in the ProFile section
caused high stress peaks were evidenced at the base of the
blade grooves and their distribution was heterogeneous
 Even with bending stresses, ProTaper section under equal
loading reached lower stress levels which were
homogeneously distributed over all the surfaces compared
to the ProFile section.
ProFile rotary instruments ProTaper rotary instruments

 The characteristics of the NiTi alloy depend on its
strongly non linear behaviour.
 The most performatory phase for the work of the NiTi
rotary instrument is the transformation phase, where one
sees the super elastic characteristic.
 To avoid an excessive and dangerous damage due to
cyclic stresses in the NiTi rotary instrument, the alloy
should work within this security phase.
 The first devices utilized were air driven. They were
mounted on dental units replacing the turbines
ENDODONTIC MOTORS

 They were soon abandoned because the variations in
the air pressure caused the instrument to have
dangerous variations of rotational speed.
 Then we had electric motors dedicated to NiTi
rotary instruments, able to maintain a perfectly
constant rotational instrument speed.
 In order to do this, the torque utilized was quite
high.
 This sometimes brought about such high stresses
that breakages of the rotary NiTi instruments
occurred inside the canal.

 To avoid fractures as much as possible, in recent
years highly sophisticated endodontic motors have
been introduced on the market, with which it
possible to control the speed as well as the
maximum torque.
Endodontic motor Tecnika Vision
(ATR and Sirona)
Endodontic motor DTC
(Aseptico, USA)

 To keep the speed constant, the torque varies
continuously depending on the cutting difficulty and the
instruments progression.
 These latest generation endodontic motors are made up
of a control system that drives the electric motor which
has a contra-angle reduction handpiece attached to its
shaft.
 The control system is able to store a large amount of
data, thereby allowing the operator to utilize many
different NiTi rotary instrument systems.

 When the maximum torque value preset by the
operator has been reached the motor will reverse the
rotation and the instrument turning anti-clockwise,
will automatically exit the canal.
Endodontic motor DentaPort
(J. Morita Corp)
Endodontic motor X-Smart
(Dentsply Maillefer)

LIFE OF THE NITI ROTARY INSTRUMENT
The obligatory questions frequently asked are:
How long do these instruments last?
How many canals are we able to shape?

The criteria that will influence the life of the instrument:
1) Original canal anatomy
2) Mechanical characteristics of the NiTi rotary
instruments
3) Rotational speed and maximum torque values when
using NiTi rotary instruments
4) Characteristics of the work carried out by the NiTi
rotary instruments
5) Operator ability

Original anatomy of the canal:
 Yared has shown that the longevity of
the instrument is strictly correlated to
the number of rotations it makes inside
the canal.
 The more complex the anatomy is, the
more wear there is in terms of increased
fatigue damage and therefore the life of
the instrument is reduced.
 Therefore the curve radius and angle of
the canal which the instrument has to
shape is determinant in the cyclic
fatigue of the instrument.

 The cutting ability of the NiTi instrument tip is not
generically very efficient in curved canals.
 This causes an immediate increase in the torsional
stress that the instrument accumulates when it must
advance in those canal sections.
 This is easily detectable by the immediate increase of
the torque values
 The torque variations can be seen on a digital and
acoustic indicator.
 This again highlights the importance of a manual
preshaping which prevents the engagement of the NiTi
rotary instrument tip against the canal walls, in this
way drastically reducing the torsional stress.

Mechanical characteristics of the selected instruments:
 Theoretically to optimize the use of NiTi rotary instruments
and to avoid fractures the instrument should be subjected to
low levels of stress.
 The more the section is able to withstand high levels of
torsional stress the more it is resistant.
 The more the section has a low bending moment, the more
compliant it is and therefore able to respect the original canal
anatomy.
 The capability of an instrument to resist the stress and at the
same moment to respect the curvature of the canal is therefore
a compromise between the torsional and bending
characteristics of its section.

 Instruments with the same characteristics have
different mechanical behaviours in relation to their
size.
 If the instrument has a small caliber, it has reduced
strength capabilities to torsional stress, if on the
contrary it is big, it is more prone to fracture because
of bending stress.

 Therefore think of small instruments having low
strength to torsional stress and large instruments
having low strength to bending stress in final
phases of shaping.
 For example, a canal with extreme curvature
should be prepared with an instrument of reduced
taper as they are more resistant to cyclic fatigue.
 If a canal that is extremely narrow and calcified is
to be prepared it is necessary to carry out an
adequate manual preshaping to reduce the
torsional stress.

 The instrument which presents the slightest sign of
plastic strain (increase/decrease of the spiral gaps)
should be eliminated immediately to avoid intracanal
fractures.

Rotational speed and maximum torque values
for NiTi rotary instruments:
 Rotational speed - should be constant
 Maximum torque - should be less than the torque
value necessary to cause plastic strain
 It is therefore essential to use an electric motor that
allows one to set the rotational speed and maximum
torque value to be used according to the
recommendation of the manufacturer for the
particular rotary NiTi rotary instruments

Characteristics of the work carried out by the
NiTi rotary instruments
 There are two factors which influence the work of
the instrument:
• the section of the working part directly
involved with the cutting
• the depth at which the instrument carries out its
work within the canal.
 The smaller the working portion of the instrument
directly involved with cutting the dentine, the
lower the torsional stresses.

 Berutti et al. have verified how many endodontic
simulators the instruments of the ProTaper System
S1, S2, F1, F2 utilized in sequence were able to
shape before breaking.
 These were the results:
• S1: 59 endodontic simulators before breaking.
• S2: 48 endodontic simulators before breaking.
• F1: 23 endodontic simulators before breaking.
• F2: 11 endodontic simulators before breaking

 A further important fact that emerged from this study is that if the
instruments of the ProTaper System work with a lower torque,
they have a considerably shorted life.
 The following results were obtained using the Tecnika ATR
endodontic motor:
• S2: torque 20%, speed 300 rpm = 28 simulators before breaking.
• S2: torque 80%, speed 300 rpm = 48 simulators before breaking.
• F1: torque 28%, speed 300 rpm = 8 simulators before breaking.
• F2: torque 40%, speed 300 rpm = 4 simulators before breaking

This notable and constant difference in the life of the
tested ProTaper System instruments resulted from the
frequent insertion of the auto reverse of the endodontic
motor when the utilizable torque was low.

Operator ability
 It has been demonstrated that the experience of the
operator is decisive in preventing the fracture of the
NiTi rotary instruments inside the canal.
 An inexperienced operator probably exercises an
excessive apical pressure during the use of the NiTi
rotary instruments.
 This brings about excessive friction of the instrument
blades against the canal walls.

 Berutti et al. studied the relationship that exists between the
experience of the operator and the time required to shape the
canals
 The experienced operator is able to shape more canals because
the average working time with each instrument is inferior to that
of an inexperienced operator.
 This causes an unnecessary stress overload which the instrument
accumulated during the excessive amount of time spent rotating
in the canals.

RECAP…
 Introduction
 History
 Classification of endodontic instruments
 Why rotary instrumentation?
 Steel Rotary Instruments
 Characteristics and Metallurgy Of NiTi Alloy
 Advances in NiTi alloy
 Functioning of NiTi Rotary instruments under Torsional
Bending stresses
 Importance of the Section of the NiTi Rotary
Instrument
 Endodontic Motors
 Life of Rotary NiTi Instrument

Speed Range –
300 to 30,000 rpm
Speed Range –
120 to 800 rpm

Speed Range –
0 to 800 rpm
X – Smart Plus Endo Motor
Speed Range –
250 to 1200 rpm

1. Assess case difficulty
2. Provide adequate access
3. Prepare with hand files up to size #20 prior to rotary
use
4. Use light touch and low rpm
5. Proceed with crown-down sequence
6. Replace rotary instruments frequently
The “Golden Rules” for NiTi Rotary Preparation
American Association of Endodontists 2008

NITI ROTARY SYSTEMS
Ingle 7th edition

ProFile System:
• Introduced by Dr. W. Ben Johnson in
1994
• C.S – Triangular U shape
• Taper – 2% to 8%
• Recommended speed – 150 to 350 rpm

 ProFiles are obtained by micromachining three parallel
furrows on a nickel titanium wire
 The surfaces of the wire between the furrows are not
sharpened so that in cross-section the instrument has a
design defined as a “triple U” with blades characterized
by flat cutting surfaces called “radial lands”
 Triple U design - increased flexibility
 The “radial lands” blades of the ProFiles are not
efficient in lateral cutting.
 The low cutting capacity and their flexibility make the
ProFiles particularly useful in the shaping of curved
canals, reducing the risk of apical tears and
transportation.

GT System:
 By Dr. S. Buchanan
 C.S –
 Taper – 4% to 12%
 Recommended speed – 300 to 500 rpm

 The Rotary GT Files present a non cutting tip, a
prefixed tip diameter and a prefixed maximum flute
diameter (MFD), multiple tapers and a blade length
inversely proportional to the taper.
 Blade direction is clockwise in the Rotary GT and
counter-clockwise in the Hand GT
 The clockwise direction of the blades and the radial
cutting planes are fundamental because they make it
possible to use the Rotary GT in continual clockwise
rotation without screw in.

 Rotary GT Files are at present available in 4
principal series, each one of which comprises 4
instruments:
• GT 20 Series comprises 4 instruments with a 0.20
mm tip diameter and tapers of .04, .06, .08 and .10

mm tip diameter and tapers of .04. .06, .08 and .10

mm tip diameter and tapers of .04, .06, .08 and .10

• GT Accessory comprises 3 instruments with a taper
of .12 and a tip diameter respectively of 0.50, 0.70
and 0.90 mm

Lightspeed instruments:
 By Dr. S. Senia
 C.S –
 Recommended speed –
initially 1000 to 2000 rpm
later manufacturer
recommended lesser speed
 No. of files – 20

 Very similar to the GG drills with a long shaft and a
working part in the shape of a very short flame.
 The long and thin shaft ensures that the LightSpeed has
an elevated flexibility but at the same time it
diminishes torque stress resistance
 For this reason LightSpeed instruments are made with
a point of separation at 18 mm from the tip, in order to
facilitate their removal incase of intracanal fracture.
 LightSpeed instruments available in the 21, 25 and 31
mm lengths, must be used from the smallest to the
largest in a stepback sequence with a typical pecking
movement

ProTaper System:
 C.S –
 6 instruments of 2 groups with 3
instruments each: Shapers with
the marking SX, S1 and S2 and
Finishers with the marking F1,
F2 and F3
 Taper – 2% to 19%
 Recommended speed – 250 to
350 rpm

 Important structural characteristics of the ProTapers are:
• robust triangular cross-section with convex sides to
increase the metal mass of the central core resistance of
the instruments
• cutting blades with cutting angles (there are no radial
lands)
• variable helical angle & variable pitch (distance
between spirals) to reduce the risk of screw in and aid
the removal of debris
• multiple increase in tapers towards the handle of the
shapers (so as to increase the flexibility in the apical
third) and decrease towards the handle in the Finishers
(so as to enlarge the apical preparation without making
the coronal third of the instrument too rigid)

K3 System:
Dr John McSpadden in 2002
 C.S –
 Taper – 2% to 6%
 Recommended speed - 300 to 350 rpm
Files used at a rotational
speed of 350 rpm were
more likely to fracture than
those used at 250 rpm and
than those used at 150 rpm
(contrary to manufacturers
recommendations)

FlexMaster System:
C.S –
Taper – 2% to 11%
Recommended rpm – 300rpm

RaCe System:
• C.S –
• Taper – 2% to 10%
• Recommended rpm – 600 to 800 rpm
• All instruments, except an orifice shaper, are used to
working length:
• .05/15 (non-cutting tip) and .04/25 (cutting tip) working in
the most apical area;
• .06/25 (noncutting tip) working in the middle and coronal
third,
• 04/30 and .04/40 (cutting tips), working apically

Quantec System:
 C.S –
 Taper – 2% to 12%
 Recommended rpm – 300 to 250 rpm
 The Quantec File is designed to enhance the balance of the
cutting actions on each wall of canal curvatures.
 Incorporating cutting edges having unequal efficiencies
causes cutting to occur on the canal wall opposite the
pressure surface.
 By using alternate cutting efficiency throughout the canal,
transportation of the central axis in curved canals is reduced

Mtwo System:
 Mtwo was one of the first NiTi systems with
instruments designed as Hedstrom files.
 C.S –
 All files of the set (04/10, 05/15, .06/20, .05/30, .04/35,
.04/40) are used to working length with the largest
instrument in size being .04/40.
 Two additional sets .04/45, .04/50, .04/60 and .06/30,
.06/35, and .06/40 are completing the system.
 If thermoplastic obturation is used, a final .07/25
instrument is also available.

Hero 642:
 Hero 642’s are mechanical instruments derived from
the Helifiles
 Taper – 2% to 6%
 Generally Hero are used in a crown down sequence
based on the reduction of the taper (6-4-2) and/or of
the diameters.
 Recommended rpm - 300 to 600 rpm

 Characterized by:
• a triple helix cross-section with three positive rake angles; there
are no radial cutting tiers as in the ProFile and Quantec
instruments, but there are cutting angles as in the ISO
instruments even though they have a different inclination;
• a higher “ residual core” inside the blades which increases the
resistance to torsional loads diminishing the risk of fracture;
• a progressive sequence of the blades to reduce the tendency to
screw in;
• three tapers which permit the reduction of the contact surfaces
between the blades and the canal walls;
• a tip that remains centered in the canal and which does not
normally come into contact with the canal walls.

Hero Shaper:
 Hero Shaper are instruments which are derived directly
from the 642 Hero.
 Hero Shaper differs from the 642 Hero :
• rake angle (helical angle) of the blades is variable and
increases from the tip towards the handle,
• pitch (distance between two spirals) increases with the
taper of the instruments,
• shorter handle allows an easier access to the posterior
teeth
• the tip is completely inactive and self guiding

 Hero Shaper series comprises three instruments
with a taper of .06 (20, 25 and 30) and three
instruments with a taper of .04 (20, 25 and 30),
available in lengths 21, 25 and 29 mm.
 Recommended speed - 300 to 600 rpm

ProTaper Gold System:
• C.S –
• Increased Flexibility
• Greater Resistance to Cyclic Fatigue
• Shorter 11 mm Handle
• Preferred Over ProTaper Universal

Hyflex CM System:
 Controlled Memory NiTi
 Proprietary Thermo mechanical Treatment
 Retain Shape After Bending Regains shape after
Sterilization
 Superior canal tracking Ability
 300 % more resistant to Cyclic fatigue than
Conventional NiTi
 Taper- 0.04,0.06 Size - #15- #60
 Speed – 500 rpm
 Torque – 2 N.cm

• Up to 700% higher fracture resistance
• Unique hardened surface
• Less filing required for treatment success
• Electrical Discharge Machining - Innovative
manufacturing process uses spark erosion to
harden the surface of the NiTi file, resulting in
superior fracture resistance and improved cutting
efficiency

ProTaper Next:
 C.S –
 Swaggering Effect-
ProTaper Next’s innovative off - centered rectangular
cross section gives the file a snake-like “swaggering”
movement as it moves through the root canal.
The off - centered cross section and the unique design
of the file generate enlarged space for debris hauling.
 Recommended speed – 300 rpm

 Intended for initial endodontic treatments, Revo-S
innovates with only 3 instruments.
 Its asymmetrical section initiates a snake-like
movement of the instrument inside the canal.
 High performance and simple to use, this sequence is
adapted for most root canal anatomies.
Revo – S System:

 Sequence of 3 instruments with asymmetrical cross-
section.
 The instrument works in a cyclic way (3C Concept):
1) Cutting
2) Clearance (debris elimination)
3) Cleaning
 Recommended speed - 250 - 400 rpm
 Snake like movement inside the canal

One Shape System:
• MicroMega innovation - : the instrument presents a
variable cross-section along the blade
• Works in continuous Rotation
• Variable Pitch
• Continuously Changing Cross section
• Anti Breakage Control-File Unwinds on use OneShape

 One Shape principle: 3 different cross-section zones.
• The first zone presents a variable 3-cutting-edge
design.
• The second, prior to the transition, has a cross-section
that progressively changes from 3 to 2 cutting edges.
• The last (coronal) is provided with 2 cutting edges.

WaveOne:
 Wave One file system from Dentsply Maillefer is a singleuse,
singlefile system to shape the root canal completely from start
to finish.
 Available in lengths of 21, 25 and 31 mm.

1. Wave One small file
• Used in fine canals.
• Tip size is ISO 21
• Continuous taper of 6%
2. Wave One primary file
• Used in most of the canals.
• Tip size is ISO 25
• An apical taper of 8% that reduces towards the
coronal end.
3. Wave One large file
• Used in large canals.
• Tip size is ISO 40.
• Apical taper of 8% that reduces towards the
coronal end.

Reciproc:
 The Reciproc instrument series possesses many similarities
to the WaveOne set of instruments.
 But differs mainly in the cross sectional design and as well
as the sizes of the three instruments available.
 WaveOne instruments are based on the ProTaper
 The Reciproc instruments are based on Mtwo.
R25 (size: 25/0.08) for smaller canals
R40 (size: 40/0.06) for medium canal
R50 (size: 50/0.06) for larger canals

Self Adjusting File (SAF):
 This was the first system developed based on this concept
and comprised a single instrument.
 Introduced by Zvi Metzger.
Concept
 The file three dimensionally adapts both longitudinally
and along the cross-section of the root canal system and
this is its most characteristic feature. This results in a
uniform cutting

Design
 Designed to be used as single-use
files.
 SAF system consisted of a hollow
compressible NiTi lattice with a
thin-walled pointed cylinder 1.5 or
2.0 mm in diameter.
 It operated with a modified
vibrating handpiece generating
3,000–5,000 vibrations/min at an
amplitude of 0.4 mm.
 Another advantage of the system
was the feature of continuous
irrigation by a silicon tube to the
irrigation hub on the file.

Twisted File Adaptive File System:
TF Adaptive file system Automatically adapts and
changes the file motion based upon the stress placed
on the instrument while in use.
Advantage
“Rotary when you want it, Reciprocation when you need it”
Continuous
rotary
movement Reciprocating
movement
Increased
Stress
Reciprocating
movement

Small(SM) Sized
canals
• SM1 – 20/0.04
• SM2 – 25/0.06
• SM3 – 35/0.04
Medium-
Large(ML) Sized
Canals
• ML1 - 25/0.08
• ML2 - 35/0.06
• ML3 - 50/0.04

XP Endo Shaper and Finisher:
 XP-Endo Shaper instrument is a rotary snake-shaped
instrument made of a proprietary alloy
 Due to this alloy, the file has an ability to change its shape
according to the temperature.
 When cooled, in its martensitic phase, the file stands
straight with a size #30 and an initial taper of 0.01.
 However, when introduced to body temperature, it
changes to its austenitic phase assuming a snake shape that
can achieve a final minimum canal preparation of 30/0.04
when using this instrument alone

 XP-Endo Finisher is an anatomical finishing file that
consists of a small-core-size (tip size 25 and
nontapered) rotary NiTi instrument.
 When submitted to body temperatures, it changes to its
austenitic phase (A-phase) assuming a spoon shape of
1.5 mm depth in the final 10 mm of its length.
 According to the manufacturer, when the instrument is
placed inside the canal in the rotation mode, the A-
phase shape allows the files to access and clean areas
that other instruments might not have reached, without
damaging dentin or altering the original canal shape.

TruNatomy System:
 By Dr. George Bruder and Dr. Ove Peters.
 Acc. to manufacturer TruNatomy offers:
• Smooth feeling during preparation
• Improved performance and efficacy
• More space for debridement and debris removal
• Respect of the natural tooth anatomy
• Preserve tooth structure

 Operates at a higher speed with less torque
(Recommended speed – 500 rpm, torque – 1.5N)
 With just 2 cutting edges, it encounters less
resistance and thus requires less applied pressure,
ensuring precision with increased ease of use
 Thermal treatment provides greater flexibility with
improved fatigue resistance

 TruNatomy Shaping Files are available in three
different sizes and lengths (21mm, 25mm & 31 mm)
 While the TruNatomy Prime shaping file is
appropriate for most cases, two additional shaping
files, the TruNatomy Small and the TruNatomy
Medium, are available to address both smaller and
larger canals.
 Manufacturer claims the clinician will experience a
fluid transition between the TruNatomy Shaping
Files.

IATROGENIC MISHAPS
Damage to the apical foramen:
 When the curved canal is deviated from the original
long axis it is often associated with loss of the apical
stop.
 Clinically, it may result in mechanical irritation of the
periapical tissues and increase the risk of extruding
irrigation solutions, debris and root canal filling
materials.

Perforation:
 This procedural error represents a communication
between the root canal space and the external root
surface.
 It may be caused from use of instruments with sharp
cutting tips in reaming or rotary working motions.
 In many instances, a perforation will be located at
the apical part toward the outer side of the canal.

Strip perforation:
 In contrast to perforation located at the apical part of
the canal, strip perforation results from over-
preparation along the inner side of the curvature in
the middle or coronal third of the canal.
 Strip perforations mainly occur in mesial roots of
mandibular molars at the furcal aspect, also know as
the “danger zone”

Elbow-formation:
• The typical picture of canal transportation is over-
preparation along the outer side of the curvature at the
apical part and along the inner side more coronally.
• The elbow-formation usually occurs between two
areas of excessive dentin removal and a narrow
portion of the canal.
• Usually, the elbow is located at the point of maximum
curvature.
• The clinically relevant adverse effects of this
procedural errors are insufficient debridement and
obturation of the canal part located apically to the
elbow-formation

Zip:
 The curved part of the canal adopts an elliptical or
“teardrop” shape at the apical end point.
 This is caused because the axis of the curved canal is
deviated towards the outer aspect and inadvertently
more dentin is removed from the outer side.
 Due to this irregular cross-sectional shape, the quality of
canal obturation is markedly reduced when employing
the cold lateral compaction technique.

Ledging:
A ledge is a platform created at the beginning of the
outer side of the curvature that hinders the instruments
from reaching the working length.
Usually, ledge formations are located in the middle or
apical part of root canals.

Canal Straightening:
The extent of apical canal transportation can be classified
as follows:
Type I: minor movement of the
position of the apical foramen,
resulting in only slight iatrogenic
relocation.
Type II: moderate movement of the
physiologic position of the foramen,
resulting in a considerable iatrogenic
relocation on the external root surface.
Type III: the physiologic position of
the root canal is severely moved,
resulting in a relevant iatrogenic
relocation of the physiologic foramen.

Prevention of Canal Transportation and Ledging
 The access cavity should be prepared so that unrestricted
access of the instruments to the apical foramen is
available
 A glide path should be created prior to canal preparation.
 When using stainless steel hand instruments (e.g., Pilot
instruments) for canal scouting, the tactile feedback
provides relevant information regarding the consistency
of the canal content, possible blockages (e.g., root canal
branches) and radiographically unseen curvatures.
 Severely curved canals should be prepared using engine
driven NiTi instruments having non-cutting tips.

 When using NiTi hand instruments, preference
should be given to the balanced-force technique.
 Instruments should not be forced into the root canal.
 Skipping instrument sizes should be avoided.
Frequent recapitulation of the canal using small hand
instruments is recommended.
 Copious irrigation should be carried out during canal
preparation to avoid any blockage of the canal
lumen.
 Instruments should never be used in dry canals.

Apical Extrusion of Debris:
 Avoiding extrusion of some debris during root
canal preparation is virtually impossible.
 During root canal preparation, necrotic or vital
pulp tissue, dentin chips, microorganisms,
irrigants and in the case of retreatment even
certain filling materials may be extruded into the
periapical tissues.
 Most common consequences of apical debris
extrusion are post-operative pain and
interappointment flare-ups

 When comparing different hand preparation
techniques to engine-driven rotary preparation, it has
been reported that hand preparation techniques using
crown-down approach, or employing cervical
flaring, were associated with less debris extrusion
than techniques involving a linear manual filing
motion.
 On the other hand, some studies reported that, when
properly used, rotary engine driven preparation does
not produce significant debris extrusion.
 Currently, the use of any types of instrument or
preparation technique is associated with some debris
extrusion.

Fracture of Instruments:
• The fracture of endodontic instruments is not an
uncommon mishap during root canal preparation.
• It may occur in 1%–6% of cases for stainless steel
instruments and approximately 0.4%–3.7% for rotary
NiTi instruments
• Basically, there are two modes of fracture: cyclic fracture
and torsional fracture.
• Cyclic fracture occurs when an instrument is used for too
long. Unfortunately many manufacturers focus on the
number of canals treated rather than the duration.

 A single torturous canal may, often, require a duration
exceeding that of several non-complicated root canals.
 Torsional fracture occurs when the tip of an
instrument is firmly engaged inside the root canal and
the motor continues to rotate.
 The torque will exceed the elastic limit and the
instrument will separate.
 Single overload of NiTi instruments has been
identified as a major reason of fractures.
 It can also occur when the flutes of an instrument are
packed with dentinal debris thereby increasing the
torque above a critical limit.

The following factors were associated with file fracture:
• Frequency of use
• Number of rotations
• Preflaring and preenlarging
• Angle of the curvature
• Radius of the curvature
Non-contributing factors are:
• Torque
• Sterilization
Controversial factors:
• Rotational speed
• Operator’s experience

CONCLUSION
 From a biological perspective, root canal treatment is
directed toward the elimination of micro-organisms
from the root canal system and the prevention of
reinfection.
 Over the last few years endodontics has undergone a
complete revolution with the introduction of the NiTi
alloy from the manufacture of initial manual to rotary
endodontic instruments.
 Technological advances in the form of rotary NiTi
instruments has led to a dramatic improvement in the
ability to shape root canals with potentially fewer
procedural complications.

 The extraordinary characteristics of NiTi alloy has
made it possible to manufacture rotary instruments
with double, triple and quadruple taper compared to
the traditional manual instruments.
 This has made it possible to achieve perfect shaping
with the use of very few instruments in a short period
of time.
 In this mechanistic age it will always be the operator
with his choices and his manual dexterity, that will
know how to make the difference.

 Ingle’s Endodontics – 7th edition
 Endodontics Vol II – Arnold Castellucci
 Grossman’s endodontic practice – 14th edition
 Textbook of endodontics – Nisha Garg & Amit Garg
 Schäfer E, Schulz-Bongert U, Tulus G. Comparison of hand
stainless steel and nickel titanium rotary instrumentation: a
clinical study. Journal of endodontics. 2004 Jun 1;30(6):432-5.
 Berutti E, Negro AR, Lendini M, Pasqualini D. Influence of
manual preflaring and torque on the failure rate of ProTaper
rotary instruments. Journal of Endodontics. 2004 Apr
1;30(4):228-30.
REFERENCES

Brochures –
 ProFile
 ProTaper
 ProTaper Next
 ProTaper Gold
 GT System
 K3
 Quantec
 RaCe
 Hero
 FlexMaster
 Mtwo
 HyFlex CM
 HyFlex EDM
 Revo – S
 OneShape
 WaveOne
 Reciproc
 Self adjusting files
 XP EndoShaper & Finisher
 TruNatomy

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