Endo Tribune UK No. 1, 2016

Twisted files and adaptive motion technology: A winning combination for safe and predictable root canal shaping / Root canal treatment with the new MTA Repair HP / Roots Summit 2016 - Premier global forum for endodontics takes place in Dubai / Irrigation dynamics in root canal therapy

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Twisted files and adaptive motion technology: A winning combination for safe and predictable root canal shaping
01 - 03 view
Root canal treatment with the new MTA Repair HP
04 - 04 view
Roots Summit 2016 - Premier global forum for endodontics takes place in Dubai
05 - 05 view
Irrigation dynamics in root canal therapy
06 - 07 view

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ENDOTRIBUNE
The World’s Endodontic Newspaper · United Kingdom Edition
www.dental-tribune.co.uk

Published in London

Vol. 10, No. 9

Twisted files and adaptive motion technology
A winning combination for safe and predictable root canal shaping
By Dr Gary Glassman, Canada; Prof. Gianluca Gambarini, Italy & Dr Sergio Rosler, Argentine
The ultimate goal of endodontic
treatment is the prevention and/or
treatment of apical periodontitis,
such that there is complete healing
and absence of infection1 while
the overall long-term goal is the
placement of a deﬁnitive, clinically
successful restoration and preservation of the tooth.2 Successful
endodontic treatment depends on
a number of factors, including
proper instrumentation, successful
irrigation and decontamination of
the root-canal system right to the
apical terminus in addition to hard
to reach areas such as isthmuses,
and lateral and accessory canals3, 4
(Fig. 1a & b).
The challenge for successful
endodontic treatment has always
been the removal of vital and
necrotic remnants of pulp tissue,
debris generated during instrumentation, the smear layer, microorganisms, and micro-toxins from
the root-canal system.5 It has been
accepted that even with the use of
rotary instrumentation, the nickel-titanium instruments currently
available only act on the central
body of the root canal, resulting
in a reliance on irrigation to clean
beyond what may be achieved
by these instruments.6 ‘Shaping
canals creates sufﬁcient space to
hold an effective reservoir of irrigant that, upon activation, can penetrate, circulate and digest tissue
from the uninstrumentable portions of the root canal system.’ 7, 8
Several challenges often arise
during root canal preparation.
Some of the most common ones
are anatomic factors that may prevent negotiation to the apical termini, as well as ledge formation,
perforation and ﬁle separation.The
introduction of Nickel-Titanium
(NiTi) alloy in endodontics presented a signiﬁcant improvement,
allowing good results in terms
of cleaning and shaping of root
canals, while reducing operative
time and minimising iatrogenic
errors.9, 10
Thanks to the superior mechanical properties of the NiTi
alloy, it was possible to use endodontic instruments of greater
tapers in continuous rotation, increasing the effectiveness and
rapidity of the cutting. However,
several studies reported a signiﬁcant risk of intracanal separation
of NiTi rotary instruments.11–14 In
fact, ﬁle separation via torsional
and cyclic fatigue has created the
biggest fear and risk for dentists
using rotary NiTi ﬁles for root
canal treatment.11, 12, 15

Because TF ﬁles are twisted and not
ground, no surface microfractures
occur on their surface and therefore do not need be polished away;
thereby not dulling the cutting
edges and retaining their efﬁcient
cutting ability.21–23

1a

1b

Figs. 1a & b: The complexity of root canal anatomy is demonstrated by these
cleared samples of maxillary molars.

Although multiple factors contribute to ﬁle separation, cyclic
fatigue has been shown as one of
the leading causes.16 Fatigue failure
usually occurs by the formation of
microcracks at the surface of the
ﬁle that starts from surface irregularities often caused by the grinding process during the manufac-

treatment technology that changes
the crystalline structure completely so the triangular cross section NiTi ﬁle blank can be twisted
while maintaining the natural
grain structure. More precisely, TF
instruments are created by taking
a raw NiTi wire in the austenite
crystalline structure phase and

Because of the increased ﬂexibility, the TFs maintains the original canal shape better, minimises
canal transportation and stays
centred even in severely curved
root canals.24, 25 In addition to the
development of heat treated TF
technology to improve the performance and safety of NiTi instruments, the ﬁle design has
also been changed with respect
ﬁle dimensions, tip conﬁguration,
cross-section and ﬂute design.
More recently, a third factor has
become important in this search
for stronger and better instruments: Movement Kinematics, the
branch of motion in which the
objects move.26

3

2

Fig. 2: Colour-Coded File Identiﬁcation. An intuitive, colour-coded system designed for efﬁciency and ease of use. Just like a
trafﬁc light – start with green and stop with red.—Fig. 3: ElementsTM Motor. Settings for TFTM Adaptive, TFTM, K3, Lightspeed,
M4 Safety Handpiece and custom settings for personal preference.

turing. During each loading cycle
microcracks develop, propagating
getting deeper in the material,
until complete separation of the
ﬁle occurs.17 All endodontic ﬁles
show some irregularities on the
surface, and inner defect, as a consequence of the manufacturing
process, and distribution of these
defects inﬂuence fracture strength
of the endodontic instruments.18, 19
Since the introduction of NiTi
in 198820, varied instrument designs with claims of superior cyclic
fatigue resistance have been propagated. However, there were no
major changes in the manufacturing process/raw materials until
the introduction of the second
generation of NiTi ﬁles, ie, M-Wire
(DENTSPLY Tulsa Dental Specialties) in 2007 and Twisted File (TF,
Kerr Endodontics Formerly Axis/
SybronEndo) in 2008.

transforming it into a different
phase of crystalline structure
(R-phase) by a process of heating
and cooling. In the R-phase, NiTi
cannot be ground but it can be
twisted. Once twisted, the ﬁle is
heated and cooled again to maintain its new shape and convert it
back into the austenite crystalline
structure, which is super elastic
once stressed. The manufacturing
process aims at respecting the
grain structure for maximum
strength as grinding creates microfracture points during the
manufacturing of the instruments.

Recent literature data shows
that a reciprocating motion can
extend cyclic fatigue resistance of
NiTi instruments when compared
to continuous rotation,27, 28 mainly
because it reduces instrument
stress. As the instrument rotates
in one direction (usually the larger
angle) it cuts and becomes engaged into the canal then it disengages in the opposite direction
(usually with the smaller angle)
and the stresses are therefore reduced. Following these concepts
new instruments have been recently commercialised; Reciproc
(VDW) and WaveOne (DENTSPLY
Maillefer), which uses speciﬁcally
developed motors that produce a
speciﬁc reciprocating movement
(using approximately 150 to 30°
angles).
This reduction of instrumentation stress (both torsional and
bending stress) is the main advantage of reciprocating movements.
It has been shown that a lot of different reciprocating movements
can be used, each one affecting the
performance and the safety of
the NiTi instruments. Therefore,
when discussing the advantages
and disadvantages of reciprocation,
the exact motion should also be
mentioned, since the actual angle
of reciprocation can have substantial inﬂuence on both the clinical
and experimental behaviour of
NiTi instruments.15
Another possible advantage
of reciprocation could be better
maintenance of original canal trajectory, mainly related to lower
instrumentation stress and consequently its elastic return. However, it must be underlined that
reciprocation does not affect the
inherent rigidity of the instruments. If a quite rigid NiTi instrument of greater taper is slightly
forced into a curved canal, it will
create more canal transportation
than a more ﬂexible one, due to its
inherent tendency to straighten.
Moreover, tip design could strongly inﬂuence canal transportation,

SM1: #20/ .04

SM2: #25/ .06

SM3: #35/ .04

ML1: #25/ .08

ML2: #35/ .06

ML3: #50/ .04

SMALL (SM)

MEDIUM/
LARGE (ML)
4

TF instruments are manufactured using a proprietary heat

For more than a decade, NiTi
instruments have been traditionally used with a continuous rotary
motion, but more recently a new
approach to the use of NiTi instruments in a reciprocating movement had been introduced by
Yared.11 The clockwise (CW) and the
counterclockwise (CCW) rotations
used by Yared were four-tenths
and two-tenths of a circle respectively and the rotational speed
utilised was 400 rpm. The concept
of using a single NiTi instrument to
prepare the entire root canal was
made possible due to the fact that

a reciprocating motion is thought
to reduce instrumentation stress.

5

Fig. 4: The motion of TFTM Adaptive instrument changes from rotary into reciprocation mode, with speciﬁcally designed CW
and CCW angles which may vary from 600–0° to 370–50°.—Fig. 5: File size reference chart.

[2] =>

ENDO NEWS

with a cutting tip being more
dangerous that a non-cutting pilot
tip.
While reciprocation with NiTi
instruments have become very
popular in recent years, with a signiﬁcant number of published articles, some of these studies have
shown that there is also inherent
disadvantages in the reciprocating

torque demand on the ﬁle, due to
entrapment of debris within the
ﬂutes. To reduce this tendency
some authors have advocated the
use of NiTi rotary glide path instruments, before using a WaveOne or Reciproc instruments, but
in this case the overall technique is
no longer a single ﬁle technique
but a more complex and more
costly technique which utilises

stant, but vary depending on the
anatomical complexities and the
intracanal stresses placed on the
instrument. This ‘adaptive’ motion
is therefore meant to reduce the
risk of intracanal failure, without
affecting performance, due to the
fact that the best movement for
each different clinical situation is
automatically selected by the
Adaptive motor. It is quite interest-

Fig. 6: Deep shaping. The clinical use of a second instrument (06/35) after the 08/25 signiﬁcantly increases the preparation
in the apical one third, improving the quality of canal shaping and allowing room for enhanced irrigation. This will also allow the use of the apical negative pressure devices such as the EndoVac to safely deliver abundant quantities of sodium hypochlorite to the apex without the risk of apical extrusion.—Fig. 7: M4 Safety Handpiece.

movements. It is well known that
a small inadvertent extrusion of
debris and irrigants into the periapical tissues is a frequent complication during the cleaning and
shaping procedures, both with
manual stainless steel and nickel-titanium rotary instrumentation techniques.29, 30 However, recent studies have shown that
commercially available reciprocating instrumentation techniques
seem to signiﬁcantly increase the
amount of debris extruded beyond
the apex31, 32 and, consequently, the
risk of postoperative pain. A clinical study comparing Reciproc and
NiTi rotary instruments has also
conﬁrmed these ﬁndings.33 Since
reciprocation movement is formed
by a wider cutting angle and a
smaller releasing angle, while rotating in the releasing angle, the
ﬂutes will not remove debris but
push them apically. Reciproc and
WaveOne motions are very similar
(even if not precisely disclosed by
manufacturers), and this fact could
also explain the higher incidence
and intensity of postoperative pain
that has been found in recent research studies.33, 34
Moreover, both WaveOne and
Reciproc techniques use a quite
rigid, large single-ﬁle of increased
taper (usually 08 taper, size 25),
which is directed to reach the apex.
In many cases, in order to reach the
apical working length, reciprocating instruments are used with apically directed pressure, which produces an effective piston to propel
debris through a patent apical foramen, and possibly directing debris
laterally, making canal debridement more difﬁcult. Since instruments are commonly used without ﬁrst performing preliminary
coronal enlargement, this may
result in a greater engagement of
the ﬁle ﬂutes and consequently
may produce more torque and/or
applied pressure on the ﬁle. Moreover, the cutting ability of a reciprocating ﬁle is decreased when
compared to continuous rotation.
Debris removal is also less, thus increasing the frictional stress and

TF Adaptive

ing that the clinician will hardly
perceive the differences in the
changing motion, due to a very sophisticated algorithm, which permits a smooth transition between
the changing angles.

The TF Adaptive technique
has been proposed in order to
maximise the advantages of reciprocation, while minimising its
disadvantages. By using a unique,
patented motion, the innovative
TF Adaptive Motion technology,
together with an original three-ﬁle
technique, most clinical cases can
be treated effectively and safely
(Fig. 2).

As far as disadvantages of
reciprocation are concerned, TF
Adaptive motion is a reciprocating
motion with cutting angles (CW
angles) much greater than WaveOne/Reciproc movements. This
results in the TF Adaptive instrument is working for a longer time
with a CW angle, which allows better cutting efﬁciency and removal

two different types of Niti instruments, glide path instruments and
then shapers.35, 15

TF Adaptive employs a patented unique motion technology,
which automatically adapts to instrumentation stress, when used
in the Elements Motor while in
TF Adaptive setting (Fig. 3). When
the TF Adaptive instrument is not
(or very lightly) stressed in the
canal, the movement can be described as a continuous rotation,
allowing better cutting efﬁciency
and removal of debris. The crosssectional and ﬂute design are
meant to perform at their best in
a clockwise motion.
More precisely, it is an interrupted motion with the following
CW-CCW angles: 600–0°. This interrupted motion is as effective as
continuous rotation in lateral cutting, allowing optimal brushing
or circumferential ﬁling for better
debris removal in oval canals.
This interrupted motion also minimises iatrogenic errors by reducing the tendency of ‘screwing in’
(aka pull down), that is commonly
seen with NiTi instruments of
great taper that are used in continuous rotation.
On the contrary, while negotiating the canal, due to increased
instrumentation stress and metal
fatigue, the motion of the TF Adaptive instrument changes into a reciprocation mode, with speciﬁcally
designed CW and CCW angles that
may vary from 600–0° to 370–50°
(Fig. 4). These angles are not con-

Endo Tribune United Kingdom Edition | 9/2016

As mentioned before, ﬂexibility is a fundamental property to
minimise iatrogenic errors while
negotiating canals, both in reciprocation and in continuous rotation. The use of a reciprocating
movement, therefore, does not signiﬁcantly help a NiTi instrument
of greater taper to negotiate
curved canals with no iatrogenic
errors. It mainly helps to reduce
instrumentation stress and the
risk of intracanal failure. In addition, a study aimed to compare the
frequency of dentinal microcracks
after root canal shaping with two
reciprocating (Reciproc and WaveOne) and one combined continuous reciprocating motion Twisted
Files Adaptive (TFA) rotary system.
Ninety molars were chosen and
divided into three groups of 30
each. Root canal preparation was
achieved by using Reciproc R25,
Primary WaveOne and TFA systems. All the roots were horizontally sectioned at 15, 9 and 3 mm
from the apex. The slices were
then viewed each under a microscope at x 25 magniﬁcation to determine the presence of cracks.
The absence/presence of cracks
was recorded, and the data were
analysed with a Chi-square test.
The signiﬁcance level was set at
P < 0.05. The results found that
instrumentation with Reciproc
produced signiﬁcantly more complete cracks than WaveOne and
TFA (P = 0.032). The TFA system
produced signiﬁcantly less cracks
then the Reciproc and WaveOne
systems apically (P = 0.004). The
study concluded that within the
limits of this study, the TFA system
caused less cracks then the full

used only when a greater apical
enlargement is needed due to
larger original canal dimensions
and/or enhanced ﬁnal irrigation
techniques. The sequences are also
different in their shaping concepts. Each ﬁle of the sequence
being used is taken to full working
length in a ‘crown down’ manner
so that the root canal wall is internally sculpted incrementally,
allowing dentin debris and tissue
to be evacuated coronally rather
than to be pushed apically. This
may reduce the risk of canal blockage and the extrusion of debris
into the apical tissues. The SM 1 ﬁle
(single colour band green, 04 taper
20 tip size) is an excellent ﬂexible
Glide Path ﬁle which may be
used with either sequence to preenlarge the canal thereby decreasing instrument stress for the next
larger size ﬁle in sequence. This
also allows better maintenance
of the original canal trajectory
(Figs. 2 & 5).
The ﬁnal apical enlargement
with a size #35 ﬁle is not only
meant to allow the use of the
Endovac (EndoVac Kerr Endodontics,
Orange, CA) irrigation technique,
but to improve canal shaping by
touching more canal walls. Figure 6
clearly shows how improved and
deeper the apical one-third shape
is when a 06 taper 35 tip instrument follows a 08 taper 25 tip instrument. This is why in the majority of cases two instruments
are much better than a single ﬁle
technique, provided that the second instrument is a ﬂexible one.
The superior ﬂexibility allowed by
the use of TF technology permits

Fig. 8: TFTM Adaptive Technique Card. Size and Sequence Determination.—Fig. 9: EndoVac Apical Negative Pressure Irrigation
System. The Master Delivery Tip (MDT) accommodates different sizes of syringes ﬁlled with irrigant, the macro cannula is
attached to the autoclavable aluminum hand piece and the micro cannula is attached to an autoclavable aluminum ﬁnger
piece. The macro cannula, the micro cannula and the MDT are connected via clear plastic tubing. The tubes are connected to
the high volume suction of the dental chair via the Multi-Port Adaptor.

of debris (and less tendency to
push debris apically and laterally),
because the ﬂutes are designed to
remove debris in a CW rotation.
This results in TF Adaptive taking
advantage of the use of a motion
that is more similar to continuous
rotation for optimal debris removal. There are obviously some
changes in the angles depending
on canal anatomy (the more complex, the smaller the CW angle), but
they do not seem to signiﬁcantly
inﬂuence the overall result. On the
contrary, these changes inﬂuence
resistance to metal fatigue, since
TF instruments used with Adaptive motion were found to have
superior resistance to cyclic fatigue
when compared to the same TF
instruments used in continuous
rotation.36

reciprocating system (Reciproc
and WaveOne). Single-ﬁle reciprocating ﬁles produced signiﬁcantly
more incomplete dentinal cracks
than full-sequence adaptive rotary motion.39
The TF Adaptive technique is
basically a three ﬁle technique,
designed to treat the majority of
cases encountered in clinical practice. Available are two sets of three
ﬁle systems, one for small, calcifying and severely curved canals and
one system for more ‘standard’
and larger canals, allowing adequate taper and increased apical
preparation in both scenarios. The
number of instruments within
each sequence can also vary and
adapt to canal anatomy, with the
last instrument of the sequence

TF Adaptive to follow these criteria, and safely enlarge canals with
minimal risk of iatrogenic errors
like tooth weakening and canal/
apical transportation. The use of
a more rigid alloy would have not
made this possible, especially in
curved canals.”15

TF Adaptive technique
TF Adaptive is an intuitive,
color-coded system designed for
efﬁciency and ease of use. The
colour-coded system is based on
a trafﬁc light. The ﬁrst instrument
in sequence is green. The second
instrument in sequence is yellow
and the third instrument in sequence, if required, is red. Green
means go. Yellow means continue
or stop. Red means stop (Fig. 2).

[3] =>

Endo Tribune United Kingdom Edition | 9/2016

ENDO NEWS

Coronal access
and glide path

Adaptive matching Paper Points
may be used to dry the canals.

1. Place rubber dam.
2. Obtain straight line coronal
access with slightly diverging
axial walls adhering to the concept of Minmimally Invasive
Endodontics.37
3. Achieve apical patency and establish an apical glide path using
#8 hand ﬁle, follow that with
a #10 hand ﬁle and continue at
least with a #15 hand ﬁle. Glide
path may be facilitated with
the M4 Safety Handpiece (Kerr
Endodontics, Orange, CA) (Fig. 7).
The pulp chamber should be
ﬁlled brimful with NaOCl (Sodium Hypochlorite).

Obturation

Canal size and
ﬁle sequence
determination (Figs. 5 & 8)
Small Canals (SM)
Using tactile feel, if you struggle to get a #15 K-File to working

Dr Gary Glassman is the author of
numerous publications. He lectures
globally on endodontics, is on staff at
the University of Toronto, Faculty of
Dentistry in the graduate department
of endodontics, and is Adjunct Professor of Dentistry and Director of Endodontic Programming for the University
of Technology, Kingston, Jamaica. Gary
is a fellow of the Royal College of Dentists of Canada, Fellow of the American
College of Dentists and the endodontic
editor for Oral Health dental journal.
He maintains a private practice, Endodontic Specialists in Toronto, Ontario,
Canada. His website is www.drgary
glassman.com and his ofﬁce website is
www.rootcanals.ca. He can be reached
at drg@drgaryglassman.com.

Gianluca Gambarini is a full-time
Professor of Endodontics, University of
Rome, La Sapienza, Dental School. He
is head of the Endodontic Department
International lecturer and researcher.
He is author of more than 450 scientiﬁc articles, three books and chapters
in other books. He has lectured all
over the world (more than 350 presentations) and has been invited as a
main speaker in the most important
international (AAE, IFEA, ESE) and
national endodontic congresses in
Europe, North and South America,
Asia, Middle East, Australia and South
Africa. Prof. Gianluca Gambarini still
maintains a private practice limited to
Endodontics in Rome, Italy.

Dr Sergio A. Rosler has been the Assistant Clinical Teacher in numerous
graduate and post-graduate Endodontic Programs and was Clinical
Fellow Teacher at Warwick Dentistry
University in the United Kingdom.
Dr Rosler has lectured at conferences
and several universities around the
world. He maintains a private practice limited to Endodontics in Buenos
Aires, Argentine and can be reached at
sergiorosler@gmail.com.

TF Adaptive matching Gutta
Percha in combination with the
Elements Free Cordless Obturation
system37 may be used to obturate
the root canal system. Alternatively,
TF Adaptive carriers may be used.

Conclusions
10

Fig. 10: CBCT (Cone Beam Computerised Tomography) three dimensional visualisation of TFA preparation (SM sequence) in a complex molar, showing proper
shape, tapered preparation and excellent maintenance of canal trajectories.
(Courtesy of Dr Lucila Piasecki, Brazil and Prof. Gianluca Gambarini, Italy)

length (WL) then the canal size
is deemed to be ‘small’. Use the
Small Pack (one colour band) and
its instrument sequence. The small
sequence may also be used in severely curved canals as well as
roots that may be very thin and
the risk of strip perforation is a
possibility.
Medium/
Large Canals (ML)
Using tactile feel, if a #15 K-File
feels loose at working length then
the canal size is deemed to be
‘medium/large’. Use the Medium/
Large Pack (two colour bands) and
its instrument sequence.
Establish working length
Working length should be established with a reliable apex
locator. A radiograph may help the
clinician as well.

TF Adaptive
canal shaping
technique
1. Use the ‘TF Adaptive’ setting on
your Elements Motor (Fig. 3).
2. Ensure the pulp chamber is
ﬂooded with NaOCl or EDTA and
make sure the ﬁle is rotating as
you enter the canal.
3. Slowly advance the green (SM1
or ML1) with a single controlled
motion until the ﬁle engages
dentin then completely withdraw the ﬁle from the canal.
Do not force apically. Do not
peck.
4. Wipe off the ﬂutes. Deliver irrigant to the pulp chamber and
conﬁrm canal patency with a
#15 handﬁle K-File.
5. Repeat steps 3 and 4 using the
ﬁle you started with until working length is achieved.
6. Repeat steps 3 and 4 with the
yellow SM2 or ML2 until the ﬁle
reaches working length. If the
desired apical size is achieved
the sequence is complete. For
larger apical sizes, repeat steps
3 and 4 with the red SM3 or ML3
until the ﬁle reaches working
length.
Note: All TFA ﬁles may be used
in a brushing manner directed
towards the external surface of
the root away from the canal
curvature when retrieving the ﬁle
from the canals.

Irrigate and dry
When irrigating with EndoVac
(apical negative pressure irrigation
system),2 in small canals, you must
take SM3 to working length. In medium/large canals, you must take
at least ML2 to working length.
Note that the Microcannula is
.32 mm in diameter (Fig. 9). TF

have also found that Adaptive
Motion Technology works well with
other ground ﬁle rotary systems
making their use safer especially
in smaller and curved canals. This
technology allows the TF Adaptive
ﬁle to adjust to intra-canal torsional forces depending on the
amount of pressure placed on the
ﬁle. This means the ﬁle is in either
a rotary or reciprocation motion
depending on the situation and
adjusts appropriately.
This winning combination results in exceptional debris removal
with the tried and trusted classic
rotary Twisted File design and less
chance of ﬁle pull down and debris
extrusion with Adaptive Motion
Technology.

TFA employs Twisted File
technology and Adaptive Motion
Technology. The TF Adaptive ﬁle
design is based on clinically proven
Twisted File technology, which
means the ﬁle is twisted to shape
for improved ﬁle durability, features R-Phase Technology to improve ﬁle ﬂexibility and strength
while maintaining the original
canal curvature minimizing canal
and apical transportation (Fig. 10).

Editorial Note: A complete list of references is available from the publisher.
This article originally appeared in
Oral Health dental journal MAY 2016.

Adaptive Motion Technology
is based on a patented, smart algorithm designed to work with the TF
Adaptive ﬁle system. The authors

Disclaimer: Drs. Gambarini and
Glassman are the inventors of Adaptive Motion and receive a nominal
royalty from Kerr.
AD

[4] =>

TRENDS & APPLICATIONS

Endo Tribune United Kingdom Edition | 9/2016

Root canal treatment with the new
MTA Repair HP
By Dr Fábio Duarte da Costa Aznar, Brazil

A 47-year-old female patient presented to our clinic with a radiograph that showed an extensive
iatrogenic perforation of the furcation area at tooth #36 (Figs. 1 & 2)
that was associated with radioAD

graphic bone loss, a vestibular
ﬁstula and pain on palpation. The
patient had previously received
urgent intervention concerning
this tooth by another clinician
owing to acute pain from pulpitis.

The case was subsequently recommended for endodontic therapy.
After an initial discussion
with the patient, anaesthetic
was administered and the tooth
was isolated. After creating a
coronary access, we clinically veriﬁed the presence of pulp necrosis and perforation. The root canal
was disinfected (crown-down)
with an irrigation agent (5 %
NaOCl) and ultrasonic activation
using straight tips (Irrisonic,
Helse). The working length was
then determined with the help
of a foramen locator. The ﬁnal
preparation of the canal was performed with the RECIPROC system (VDW).
The prepared area was cleaned
and reﬁned with an ultrasonic
diamond tip (E7D, Helse). In addition to the intra-canal disinfection process, calcium hydroxide (Ultradent) placed in the
furcation area was exchanged
every two weeks, during which
time the symptoms were alleviated.
The obturation was performed according to the thermomechanical Tagger hybrid
technique (Fig. 3) using the GutaCondensor (Maillefer), TP guttapercha cones (DENTSPLY) and the
MTA-based sealer MTA-Fillapex
(Angelus). After the thermomechanical compaction, the guttapercha was cut and vertical
condensation was performed
using a cold plugger. The area
of the perforation was then

Figs. 1 & 2: Initial clinical and radiographic appearance of tooth #36.—Fig. 3:
Obturation of the root canal.—Figs. 4 & 5: Clinical photograph and radiograph
of the MTA Repair HP ﬁlling.—Fig. 6: The cavity was sealed with a glass ionomer
cement.—Fig. 7: Radiograph taken two months after treatment.

cleaned and reﬁlled with calcium
hydroxide.

MTA Repair HP. No postoperative
complications were reported.

After 15 days, we began to seal
the prepared area and initially
veriﬁed that the area had dried
properly. The prepared area was
ﬁlled with MTA Repair HP according to the manufacturer’s instructions, applied with the MTA
Applicator (both Angelus). Clinical and radiographic criteria were
used to determine correct ﬁlling
with the material (Figs. 4 & 5), and
a glass ionomer cement (3M) was
applied to seal and protect the
area (Fig. 6).

At the two-month follow-up
visit, bone formation in the
furcation area was detected. No
further symptoms were reported
(Fig. 7).

After temporary restoration,
we observed the tooth radiographically and found proper
sealing of the furcation area with

Dr Fábio Duarte
da Costa Aznar
is a specialist
in endodontics at the
Hospital for
Rehabilitation
of Craniofacial
Anomalies at the University of São
Paulo in São Paulo, Brazil. He can be
contacted at fabio@aznar.com.br.

[5] =>

TRENDS & APPLICATIONS

Endo Tribune United Kingdom Edition | 9/2016

Roots Summit 2016
Premier global forum for endodontics takes place in Dubai
By DTI
DUBAI, UAE: This year’s ROOTS
SUMMIT, which has drawn dental
professionals to various locations
all over the world in the past
decade, will take place from Nov. 30
to Dec. 3 at the Crowne Plaza Dubai
hotel in the United Arab Emirates.
Aimed at updating participants
about the latest in endodontic
treatment, an unparalleled series
of lectures and workshops will be
held by global opinion leaders in
the field.

izers anticipate a large turnout for
this year’s meeting. Various sponsorship opportunities are available, including booth space, as well
as sponsorships of workshops,
hands-on courses, meeting bags
and social events.

Online registration for the
ROOTS SUMMIT is now open at
www.roots-summit.com. Dental
professionals are also invited to
join the ROOTS Facebook group
and like the ROOTS SUMMIT 2016
Facebook page.
AD

www.buymetabiomedonline.com

Although the meeting will focus
exclusively on the latest techniques and technologies in endodontics, the organizers have
strongly encouraged not only dentists specializing in the field to
attend but all who have an interest
in endodontics, including general
dentists and manufacturers and
suppliers of endodontic products.
Overall, about 700 attendees are
expected.
Over the past 15 years, the ROOTS
SUMMIT has grown significantly.
The community originally started
as a mailing list of a large group of
endodontic enthusiasts in the
1990s. After the establishment of
a dedicated Facebook group three
years ago, membership increased
from 1,000 to more than 20,000.
Today, the group is composed of
members from over 100 countries.
Previous ROOTS SUMMITS have
been held in Canada, the US,
Mexico, Spain, the Netherlands,
Brazil and last year in India. These
meetings have been known for
the strength of their scientific
programs and their relevancy to
clinical practice. The lectures,
workshops and hands-on courses
scheduled for this year’s meeting
will be no exception. More than
15 distinguished experts are presenting during the conference.
For the summit in Dubai, the
organizers have partnered with
Dental Tribune International (DTI)
and the Dubai-based Centre for
Advanced Professional Practices
(CAPP) for the first time. With its
international network, composed
of the leading publishers in dentistry, DTI reaches more than
650,000 dental professionals in
90 countries through its print,
online and educational channels,
as well as a number of special
events.
Over the past decade, CAPP has
been able to establish first-class
standards for continuing dental
education programs not only in the
UAE but also across the Middle East.
Since 2012, CAPP has been affiliated
with DTI as a strong local partner
in the Middle East.
Based on the successes of previous ROOTS SUMMITS, the organ-

“Accuracy does matter!”
“In the presence of NaOCI or saline,
measurements from i-Root were
significantly more accurate than those
from the other apex locators.”

Cordless Gutta Percha Obturator

Digital Apex Locator

I-ROOT

Best accuracy in any
root canal condition:
Dry, Bleeding, Wet, Saline, EDTA, NaOCl, Chlorhexidine, etc.
i-Root is a 5 th generation
electronic apex locator using
dual
frequencies.
Apical
constrictions can be measured
exactly thanks to the core
technology
inherited
and
improved from the e-Magic
Finder (EMF-100 and DLX)
series apex locator.

META BIOMED INC.
121 Independence Lane, Chalfont, PA 18914, USA
Tel.: +1 267-282-5893 Fax: +1 267-282-5899
e-mail: europe@metabiomed-inc.com

i-Root Advantages …
» Measurement by both eyes and ears
simultaneously
» Color display and ease of use
» Stylish and ergonomic design
» Self-test in case of failure
» Long-lasting (60+hours) lithium-ion
battery inside
» Auto power-off for saving battery life
» Stability and durability for maximum
usage

It’s Convenient!
E&Q Master comes with removable and
rechargeable batteries enabling continuous power supply during the treatment.

It’s Safe!
E&Q Master operates at low voltage. It
ensures electrical safety during dental
procedure.

It’s Quick & Simple!
E&Q Master consists of two units enables
both delicate filling at apex and smooth
backfill.

[6] =>

TRENDS & APPLICATIONS

22

Endo Tribune United Kingdom Edition | 9/2016

Irrigation dynamics in root canal therapy
By Anil Kishen, Canada
Irrigation dynamics deals with the
pattern of irrigant ﬂow, penetration,
exchange and the forces produced
within the root canal space. Current
modes of endodontic irrigation include the traditional syringe needle
irrigation or physical methods, such
as apical negative-pressure irrigation or sonic/ultrasonically assisted
irrigation. Since the nature of irrigation inﬂuences the ﬂow of irrigant
up to the working length (WL) and
interaction of irrigant with the canal
wall, it is mandatory to understand
the irrigation dynamics associated
with various irrigation techniques.
Endodontic irrigants are liquid
antimicrobials used to disinfect
microbial bioﬁlms within the root
canal. The process of delivery of
endodontic irrigants within the
root canal is called irrigation. The
overall objectives of root canal irrigation are to inactivate bacterial
bioﬁlms, inactivate endotoxins,
and dissolve tissue remnants and
the smear layer (chemical effects)
in the root canals, as well as to allow
the ﬂow of irrigant entirely through
the root canal system, in order to
detach the bioﬁlm structures and
loosen and ﬂush out the debris
from the root canals (physical effects). While the chemical effectiveness will be inﬂuenced by the concentration of the antimicrobial and
the duration of action, the physical
effectiveness will depend upon the
ability of irrigation to generate optimum streaming forces within the
entire root canal system.
The ﬁnal efﬁciency of endodontic disinfection will depend upon

1a

1b

1c

1d

Figs. 1a–d: Velocity magnitude of irrigation showing the extent of dead zone. With the open-ended needle tip (a), the velocity progressively decreased 1.5 mm apical
from the tip. With the side-vented needle tip (b), there was a much lower velocity than with the open-ended tip, and it extended only 0.5 mm. With the apical
negative-pressure irrigation (c), there was a constant velocity slightly higher than the side-vented needle irrigation that was constant as the irrigant moved coronally.
The ultrasonically assisted irrigation (d) showed the highest magnitude of velocity, constant to at least 3 mm coronal to the tip placement.35

both chemical and physical effectiveness.1–3 It is important to realise
that even the most powerful irrigant will be of no use if it cannot
penetrate the apical portion of the
root canal, interact with the root
canal wall and exchange frequently
within the root canal system.1

Syringe irrigation
Irrigation methods are categorised as positive-pressure or

negative-pressure, according to
the mode of delivery employed. 4
In positive-pressure techniques,
the pressure difference necessary
for irrigant ﬂow is created between a pressurised container
(e.g. a syringe) and the root canal.
In negative-pressure techniques,
the irrigant is delivered passively
near the canal oriﬁce and a suction tip (negative-pressure) placed
deep inside the root canal creates
a pressure difference. The irrigant

2a

2b

2c

2d

then ﬂows from the oriﬁce towards the apex, where it is evacuated. A detailed understanding
of the irrigation dynamics associated with syringe-based irrigation
would aid in improving its effectiveness in clinical practice.
Irrigant flow during
syringe irrigation
The ﬂow of irrigants is inﬂuenced by its physical characteristics, such as density and viscosity.5

Figs. 2a–d: Time-averaged distribution of shear stress on the root canal wall showing a more uniform distribution on the canal wall with the open-ended needle tip (a).
The side-vented needle tip (b) showed a localised region with a high amount of shear stress, while there was not an observable level with the EndoVac irrigation (Kerr; c).
The ultrasonically assisted irrigation (d) displayed the highest levels of shear stress over the greatest area of the canal wall.35

These properties for the commonly used endodontic irrigants
are very similar to those of distilled water.6, 7 The surface tension
of endodontic irrigants and its decrease by surfactants have also
been studied extensively. The rationale of this combination is that
it may signiﬁcantly affect (a) the
irrigant penetration into dentinal
tubules and accessory root canals8, 9 and (b) the dissolution of
pulp tissue.10 However, it is important to note that surface tension
would only inﬂuence the interface
between two immiscible ﬂuids,
and not between the irrigant
and dentinal ﬂuid.5, 11 Experiments
have conﬁrmed that surfactants
do not enhance the ability of
sodium hypochlorite to dissolve
pulp tissue12, 13 or the ability of
chelating agents to remove the
smear layer.14, 15
The type of needle used has
a signiﬁcant effect on the ﬂow
pattern formed within the root
canal, while parameters such as
depth of needle insertion and size
or taper of the prepared root canal
have only a limited inﬂuence.16–19
Generally, the available needles
can be classiﬁed as closed-ended
and open-ended needles. In the
case of open-ended needles (ﬂat,
bevelled, notched), the irrigant
stream is very intense and extends apically along the root
canal. Depending upon the root
canal geometry and the depth of
needle insertion, reverse ﬂow of
irrigant occurs near the canal wall
towards the canal oriﬁce.
In the case of closed-ended
needles (side-vented), the stream
of irrigant is formed near the apical side of the outlet and is directed apically. The irrigant tends

[7] =>

Endo Tribune United Kingdom Edition | 9/2016

TRENDS & APPLICATIONS

tive-pressure irrigation did not
generate marked wall shear stress
values, but allowed the ﬂow of irrigant consistently up to the WL.
It was the safest mode of irrigation
when used close to the WL. The
passive ultrasonically assisted
irrigation generated the highest
wall shear stress. The use of combined methods to obtain optimum disinfection and to circumvent the limitations of one
method is recommended.

to follow a curved route around
the needle tip, towards the coronal
oriﬁce. The ﬂow of irrigant apical
to the exit of the needle is generally observed to be a passive ﬂuid
ﬂowing zone (dead zone), while
the ﬂow of irrigant in the remaining aspect of the root canal is observed to be an active ﬂuid ﬂowing zone (active zone; Figs. 1a–d &
2a–d). A series of vortices of ﬂowing irrigant are generated apical
to the tip. The velocity of irrigant
inside each vortex decreases towards the apex.

Irrigant refreshment
Irrigant exchange in the root
canal system is a key prerequisite
for achieving optimum chemical
effect, because the chemical efﬁcacy of the irrigants are known to
be rapidly inactivated by dentine,
tissue remnants or microbes.24, 26–27
Investigations have explained the
limitations in the irrigant refreshment apical to needles.21, 28–30 Enlarging the root canal to place the
needle to a few millimetres from
the WL and ensuring adequate
space around the needle for reverse ﬂow of the irrigant towards
the canal oriﬁce allow effective
irrigant refreshment coronal to
the needle tip.17, 19 Furthermore,
increasing the volume of irrigant
delivered could help to improve
refreshment in such cases.20, 31–32
The effect of curvature on irrigant exchange has been studied
indirectly by Nguy and Sedgley.33
They report that only severe curvatures in the order of 24–28°
hampered the ﬂow of irrigants.
If the canal is enlarged to at least
size 30 or 35 and a 30-gauge ﬂexible needle placed near the WL is
used, then irrigant refreshment
can be expected even in severely
curved canals.
Wall shear stress
The frictional stress that occurs between the ﬂowing irrigant
and the canal wall is termed “wall
shear stress”. This force is of relevance in root canal irrigation because it tends to detach microbial
bioﬁlm from the root canal wall.
Currently, there is no quantitative
data on the minimum shear stress
required for the removal of micro-

Large needles when used
within the root canal hardly penetrate beyond the coronal half of
the root canal. Currently, smallerdiameter needles (28- or 30-gauge)
have been recommended for root
canal irrigation.20, 21 This is mainly
because of their ability to advance
further up to the WL. This facilitates better irrigant exchange and
debridement.22–24 In addition, the
use of a larger needle would result
in decreased space being available
for the reverse ﬂow of irrigant between the needle and the canal
wall. This scenario has been associated with (a) an increased apical
pressure for open-ended needles
and (b) decreased irrigant refreshment apical to the tip for closedended needles.17–19 The inﬂuence of
tooth location (mandibular, maxillary) on irrigant ﬂow has been
observed to be minor.16, 25

Editorial note: A list of references is
available from the publisher.

bial bioﬁlm from the canal wall.
Yet, the nature of wall shear
stresses produced within the root
canals during irrigation provides
an indication of the mechanical
debridement efﬁcacy.
In open-ended needles, an area
of increased shear wall stresses develops apical to the needle tips,
while in closed-ended needles,
a higher maximum shear stress
is generated near their tips, on
the wall facing the needle outlet.34
Thus, in open- and closed-ended
needles, optimum debridement is
expected near the tip of the needle.16, 34 Consequently, it is necessary to move the needle inside the
root canal, so that the limited area
of high wall shear stress involves as
much of the root canal wall as possible. The maximum shear stress
decreases with an increase in canal
size or taper. Thus, overzealous
root canal enlargement above
a certain size or taper could diminish the debridement efﬁcacy
of irrigation (Figs. 1a–d & 2a–d).

Conclusion

dle should be placed 2 or 3 mm
short of the WL to ensure adequate irrigant exchange and high
wall shear stress, while reducing
the risk of extrusion.

The requirements of adequate
irrigant penetration, irrigant exchange, mechanical effect and
minimum risk of apical extrusion
oppose each other and a subtle
equilibrium is required during
irrigation. Ideally, in a canal enlarged to size 30 or 35 and taper
0.04 or 0.06, an open-ended nee-

In the case of a closed-ended
needle, placement should be
within 1 mm short of the WL, so
that optimum irrigant exchange
can be ensured. The apical nega-

The Dental Tribune
International Magazines

Enhancing irrigation
dynamics using physical
irrigation methods
Fluid dynamics studies on
apical negative-pressure irrigation
have demonstrated maximum
apical penetration of the irrigant,
without any irrigant extrusion.
This ﬁnding highlights the ability
of apical negative-pressure irrigation to be safely used at the WL,
circumventing the issues of vapour lock effect.35 Nonetheless, the
apical negative-pressure irrigation
produced the lowest wall shear
stress. This decrease in the wall
shear stress could be attributed in
part to the reduction in the ﬂow
rate with this irrigation system.
Passive ultrasonically assisted
irrigation, when compared with
other irrigation methods, showed
the highest wall shear stress along
the root canal wall, with the highest turbulence intensity travelling
coronal from the ultrasonic tip position. The lateral movement of the
irrigant displayed by this method
has important implications with
respect to its ability to permit better interaction between the irrigant and the root canal wall, and
to potentially enhance the interaction of irrigants with intra-canal
bioﬁlms2, 3, 35 (Figs. 1a–d & 2a–d).

Anil Kishen obtained his dental education
in India and
is Professor of
Endodontics at
the University
of Toronto’s
Faculty of Dentistry in Canada. He
can be contacted at anil.kishen@
dentistry.utoronto.ca.

www.dental-tribune.com

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Dental Tribune International

ESSENTIAL
DENTAL MEDIA
www.dental-tribune.com

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[cover] => Endo Tribune UK No. 1, 2016

[toc] => Array ( [0] => Array ( [title] => Twisted files and adaptive motion technology: A winning combination for safe and predictable root canal shaping [page] => 01 ) [1] => Array ( [title] => Root canal treatment with the new MTA Repair HP [page] => 04 ) [2] => Array ( [title] => Roots Summit 2016 - Premier global forum for endodontics takes place in Dubai [page] => 05 ) [3] => Array ( [title] => Irrigation dynamics in root canal therapy [page] => 06 ) ) [toc_html] =>

Table of contents

[toc_titles] =>

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