Tạp chí nội nha OPUS tháng 01+02/2014 Vol.7 No.1

Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (13.84 MB, 60 trang )

a revolutionary company that aims to redene
and transform traditional root canal therapy
So·nen·do:
Visit: Page 6
Clinical management
of teeth with
incomplete root
formation
Dr. Siju Jacob
PAYING SUBSCRIBERS EARN 24
CONTINUING EDUCATION CREDITS
PER YEAR!
A conservative
approach for internal
bleaching of a vital
anterior tooth with
calciﬁed pulp chamber
Drs. David Keinan and
Eugene A. Pantera Jr.
clinical articles • management advice • practice proles • technology reviews
January/February 2014 – Vol 7 No 1
PROMOTING EXCELLENCE IN ENDODONTICS
Corporate insight
Sonendo
®
The importance
of a reproducible
glide path
Drs. Yosef Nahmias,
Imran Cassim, and
Gary Glassman

Feedback –
lateral thinking
Jacqui Goss
BUC
®
Ultrasonics
Obturation Ultrasonics Surgery
Use for Access Refinement, Retreatment, and Restorative
procedures. There’s a BUC tip ready to accomplish a
multitude of endodontic treatment challenges.
Call (800) 344-1321 today to receive
20% off your next ultrasonic tip order!
© 2014 Obtura Spartan Endodontics. See instructions for use. Rx Only. Products may not be available in all areas. Please contact your Obtura
Spartan Endodontics Sales Representative for availability and pricing. Obtura Spartan Endodontics – 2260 Wendt Street, Algonquin, IL 60102.
INTRODUCTION
Volume 7 Number 1 Endodontic
practice
1
January/February 2014 - Volume 7 Number 1
ASSOCIATE EDITORS
Julian Webber BDS, MS, DGDP, FICD
Pierre Machtou DDS, FICD
Richard Mounce DDS
Clifford J Ruddle DDS
John West DDS, MSD
EDITORIAL ADVISORS
Paul Abbott BDSc, MDS, FRACDS, FPFA, FADI, FIVCD
Professor Michael A Baumann
Dennis G Brave DDS
David C Brown BDS, MDS, MSD

L Stephen Buchanan DDS, FICD, FACD
Gary B Carr DDS
Arnaldo Castellucci MD, DDS
Gordon J Christensen DDS, MSD, PhD
B David Cohen PhD, MSc, BDS, DGDP, LDS RCS
Stephen Cohen MS, DDS, FACD, FICD
Simon Cunnington BDS, LDS RCS, MS
Samuel O Dorn DDS
Josef Dovgan DDS, MS
Tony Druttman MSc, BSc, BChD
Chris Emery BDS, MSc. MRD, MDGDS
Luiz R Fava DDS
Robert Fleisher DMD
Stephen Frais BDS, MSc
Marcela Fridland DDS
Gerald N Glickman DDS, MS
Kishor Gulabivala BDS, MSc, FDS, PhD
Anthony E Hoskinson BDS, MSc
Jeffrey W Hutter DMD, MEd
Syngcuk Kim DDS, PhD
Kenneth A Koch DMD
Peter F Kurer LDS, MGDS, RCS
Gregori M. Kurtzman DDS, MAGD, FPFA, FACD, DICOI
Howard Lloyd BDS, MSc, FDS RCS, MRD RCS
Stephen Manning BDS, MDSc, FRACDS
Joshua Moshonov DMD
Carlos Murgel CD
Yosef Nahmias DDS, MS
Garry Nervo BDSc, LDS, MDSc, FRACDS, FICD, FPFA
Wilhelm Pertot DCSD, DEA, PhD

David L Pitts DDS, MDSD
Alison Qualtrough BChD, MSc, PhD, FDS, MRD RCS
John Regan BDentSc, MSC, DGDP
Jeremy Rees BDS, MScD, FDS RCS, PhD
Louis E. Rossman DMD
Stephen F Schwartz DDS, MS
Ken Serota DDS, MMSc
E Steve Senia DDS, MS, BS
Michael Tagger DMD, MS
Martin Trope, BDS, DMD
Peter Velvart DMD
Rick Walton DMD, MS
John Whitworth BchD, PhD, FDS RCS
CE QUALITY ASSURANCE ADVISORY BOARD
Dr. Alexandra Day BDS, VT
Julian English BA (Hons), editorial director FMC
Dr. Paul Langmaid CBE, BDS, ex chief dental ofﬁcer to the Government for
Wales
Dr. Ellis Paul BDS, LDS, FFGDP (UK), FICD, editor-in-chief Private Dentistry
Dr. Chris Potts BDS, DGDP (UK), business advisor and ex-head of Boots
Dental, BUPA Dentalcover, Virgin
Dr. Harry Shiers BDS, MSc (implant surgery), MGDS, MFDS, Harley St referral
implant surgeon
PUBLISHER | Lisa Moler
Email: Tel: (480) 403-1505
MANAGING EDITOR | Mali Schantz-Feld
Email: Tel: (727) 515-5118
ASSISTANT EDITOR | Elizabeth Romanek
Email: Tel: (727) 560-0255

EDITORIAL ASSISTANT | Mandi Gross
Email: Tel: (727) 393-3394

DIRECTOR OF SALES | Michelle Manning
Email: Tel: (480) 621-8955
NATIONAL SALES/MARKETING MANAGER
Drew Thornley
Email: Tel: (619) 459-9595
PRODUCTION MANAGER/CLIENT RELATIONS
Adrienne Good
Email: Tel: (623) 340-4373

PRODUCTION ASST./SUBSCRIPTION COORD.
Jacqueline Baker
Email: Tel: (480) 621-8955

MedMark, LLC
15720 N. Greenway-Hayden Loop #9
Scottsdale, AZ 85260
Tel: (480) 621-8955 Fax: (480) 629-4002
Toll-free: (866) 579-9496 Web: www.endopracticeus.com
SUBSCRIPTION RATES
1 year (6 issues) $99
3 years (18 issues) $239
© FMC, Ltd 2014.
All rights reserved. FMC is part of the specialist
publishing group Springer Science+Business
Media. The publisher’s written consent must be
obtained before any part of this publication may be reproduced in any form whatsoever, including
photocopies and information retrieval systems. While every care has been taken in the preparation

of this magazine, the publisher cannot be held responsible for the accuracy of the information
printed herein, or in any consequence arising from it. The views expressed herein are those of the
author(s) and not necessarily the opinion of either Endodontic Practice or the publisher.
T
he beginning of the New Year usually brings an examination of what we’ve learned from the past
and a prediction of what lies ahead, and such examinations are critical to maintaining a standard
of excellence in our discipline. With regard to our endodontic practices, it’s clear that the increasing
pace of innovation is revolutionizing the way we practice, as it will change every form of healthcare
practice. The areas of most rapid innovation within endodontics will include cone-beam computed
tomography with new algorithms to improve assessments and facilitate surgical guidance, enhanced
disinfection and shaping techniques, nanotechnology, innovative advances in obturation that promise
safer treatment, improved workﬂow, and better outcomes and regenerative procedures. Stringent
laboratory and clinical evaluations will be validating these innovations at an increasing pace, and more
sophisticated studies will present clinicians with rigorously examined innovation opportunities that will
provide very signiﬁcant improvements to the practice of endodontics. As in most forms of medicine,
it is not only the rate of change but the degree of difference that is increasing. The adoption of such
innovations is becoming ever more compelling. Conversely, ignoring innovation is becoming an ever-
increasing professional risk.
Over the past 50 years, change management has evolved as a recognized discipline. It was
once a viable belief that specialists could achieve success by using the same treatments and business
strategies for the greater part of their clinical career. For the current community of endodontists, such
a notion is seriously ﬂawed. Today, there are new products, technological developments, increased
competition, and a changing workforce that require us to change course in order provide the most
successful outcomes for our patients and to stay competitive.
Most successful companies undergo moderate organizational change yearly and major changes
every 4 to 5 years.
1
But in spite of all this management attention, most studies show only moderate
success for organizational change. This would suggest that Kotter’s classic eight success factors
2

is
also ﬂawed. What is going on here? Perhaps two additional factors need to be considered, both of
which may contradict other notions that served us in the past:
• Change should not be episodic. Rather than considering change as a planned and deﬁned part
of our business plan, we should integrate change into the way we execute our business plan.
This means that new approaches to treatment and business operations need to be examined on
a continual basis and that we, as leaders of our practices, should adopt behavioral patterns that
transform rather than maintain. This requires changing the fundamental values and principles of
our organization and the individuals within it. Each member is continuously seeking better ways to
operate as part of a team to improve results. But consider such a concept carefully, because this
level of transformation does not require management. It requires leadership.
• Change should not be hierarchical. Change from the top can never be adequate to the challenges
of making the myriad of changes required to improve a complex organization. Rather than deciding
and dictating change, the best practice leaders will inspire and coach change — structuring their
organizations to actually breed ideas for improvement. In a recent case study, Kotter talks about
the need to accelerate change by using a dual organizational structure. The problem is that most
businesses have a hierarchical structure that maintains processes very well, but resists change.
How many of our practices operate this way? Kotter proposes a parallel structure where employees
at all levels are invited to contribute to change in a different, but complementary, way. He stated that
creating a sense of urgency around a single opportunity (or problem) is a good way to start
3
and
to get people accustomed to contributing ideas independently of management roles and structure.
Any size practice can beneﬁt from such a parallel concept: Daily management of patient ﬂow and
procedures can be managed by a hierarchy of priorities and team member roles, but ideas for
improvement should ﬂow in parallel, unimpeded by hierarchy.
So as the New Year begins, we must consider a qualitative review of our perspectives on treatment
and the organizational culture of our practices. Most successful change efforts require creating a
change-capable organization that is always ready to examine and adapt to new treatment protocols
and ofﬁce operational demands, all supported by the evidence and metrics, respectively. This means

establishing a sense of urgency and creating a strategy that is supple and ready for modiﬁcation as
conditions change.
At the Harvard Medical School 2013 Class Day address, Dr. Bruce Donoff, dean of the Harvard
School of Dental Medicine, said, “We educated you in a way that does not simply repeat the lectures
of the past but prepares you to understand and see new knowledge in the continuously changing ﬁeld
as well as in the wider world.”
4
I would encourage us all to improve our individual, staff, and practice abilities to beneﬁt from the
ongoing stream of innovation that will enable us to continuously improve patient care. It is an exciting
age in which to be practicing dental medicine. Best wishes for this New Year and years ahead.
Martin D. Levin, DMD
Diplomate, American Board of Endodontics
Clinical Associate Professor of Endodontics, University of Pennsylvania
www.endonet.com and www.endocc.com
Dental medicine in an age of change
1. Allen, SA. Organizational choices and general management inﬂuence networks in divisionalized companies. Academy of Management Journal. 1978;21(3):341-
365.
2. Kotter, JP. Leading change. Boston: Harvard Business Review Press; 1996.
3. Kotter, JP. Accelerate! Harvard Business Review. 2012;90(11): 44-58.
4. Harvard Medical School. Change in Medicine theme for new HMS grads. Harvard Medical School News, May 30, 2013. Http://hms.harvard.edu/news/change-
medicine-theme-new-hms-grads-5-30-13. Accessed January 1, 2014.
TABLE OF CONTENTS
Clinical
Clinical guidelines for the use of
ProTaper Next
™
instruments:
part one
Drs. Peet J. van der Vyver and
Michael J. Scianamblo discuss the

clinical guidelines for using
ProTaper Next
™
instruments 12
BT-Race — Biologic and
conservative root canal
instrumentation with the ﬁnal
restoration in mind
Drs. Gilberto Debelian and
Martin Trope explore the
BT-Race system 22
A conservative approach for
internal bleaching of a vital
anterior tooth with calciﬁed pulp
chamber
Drs. David Keinan and Eugene
A. Pantera Jr. solve a common
endodontic problem in a
conservative way 25
2 Endodontic
practice
Volume 7 Number 1
Clinical 7
Accuracy of a new apex locator in ex-vivo teeth using
scanning electron microscopy
Drs. Maria Bonilla, Taner Cem Sayin, Brenda Schobert, and Patrick Hardigan
compare the accuracy of root canal working lengths in 200 ex-vivo teeth
determined using a fourth-generation electronic apex locator and a new ﬁfth-
generation electronic apex locator
ON THE COVER

Cover photo courtesy of Drs. Peet J. van
der Vyver and Michael J. Scianamblo.
Article begins on page 12.
Corporate insight 6
Sonendo
®
— A new paradigm in endodontics
At the 2014 AAE Annual Session, Sonendo is debuting its Multisonic
Ultracleaning System that uses a mixture of irrigating ﬂuids and sound waves to
clean inside the roots of teeth.
simple, adaptable endodontic solutions
Perfect delivery.
Optimal performance.
Easy removal.
UltraCal
®
XS
800.552.5512
ultradent.com
Scan to watch
a short video of
UltraCal XS.
Don’t change your technique.
Make it easier with UltraCal
®
XS
and Citric Acid 20%.
NaviTip tip delivers UltraCal XS where it is
needed in the canal.
©2013 Ultradent Products, Inc. All Rights Reserved.

UltraCal
®
XS and Citric Acid 20%
UltraCal XS, a uniquely formulated calcium hydroxide paste (pH 12.5), can be easily delivered with the NaviTip
®
tip exactly
where it is needed in the canal. Calcium hydroxide offers strong antimicrobial effects and potentially stimulates the healing of
bone to promote healing in infected canals.
1
For two-appointment RCTs, no other medicament works better than UltraCal XS.
When it comes time to remove UltraCal XS from the canal, look no further than Ultradent’s Citric Acid 20%, delivered with the
NaviTip FX tip. Citric Acid 20% easily dissolves calcium hydroxide, and the small bers attached to the NaviTip FX tip easily
scrub the walls of the canal, which also helps remove the smear layer. So you know the canal is ready for obturation.
1. Gomes BP, Ferraz CC, Vianna ME, Rosalen PL, Zaia AA, Teixeira FB,
et al. In vitro antimicrobial activity of calcium hydroxide pastes and their
vehicles against selected microorganisms.
Braz Dent J.
200 2;13(3):155- 61.
Use NaviTip
®
tip to place
UltraCal
®
XS in the canal, and
use Citric Acid with the NaviTip
®

FX
®
tip to easily remove it.

NaviTip tip
NaviTip FX tip
with brush bers
TABLE OF CONTENTS
Continuing
education
The importance of a reproducible
glide path
Drs. Yosef Nahmias, Imran Cassim,
and Gary Glassman discuss how
rotary and reciprocating instruments
that follow a designated route will
result in more successful outcomes
and minimal iatrogenic mishaps 28
Clinical management of teeth with
incomplete root formation
Dr. Siju Jacob discusses treatment
techniques for teeth with incomplete
root formation 34
Abstracts
The latest in endodontic research
Dr. Kishor Gulabivala presents the
latest literature, keeping you up-to-
date with the most relevant research
41
Anatomy matters
Endodontic accountability: The
“X” factor, part 9
Dr. John West discusses knowledge,
skill, and willingness in endodontics

43
Endospective
The cookbook’s not working —
what’s next?
Dr. Rich Mounce discusses a superior
method for cleaning canals 48
Product insight
What is the ideal endodontic
interappointment medicament,
its most effective placement and
removal technique?
Drs. Carlos A.S. Ramos, Richard D.
Tuttle, and Mr. Daniel C. White explain
the beneﬁts of UltraCal
®
XS 50
Practice
management
Feedback – lateral thinking
Jacqui Goss explains how to gather
reliable patient feedback 52
Materials &
equipment 54
Diary 56
4 Endodontic
practice
Volume 7 Number 1
Clinical
management
of teeth

34
ORTHOPHOS XG 3D
ORTHOPHOS XG 3D
The right solution for
your diagnostic needs.
Implantologists
will appreciate the
seamless clinical
workﬂow from initial
diagnostics, to treatment
planning, to ordering
surgical guides and ﬁnal
implant placement.
Endodontists
will enjoy instantly
viewable 3D volumetric
images for revealing
and measuring canal
shapes, depths
and anatomies.
Orthodontists
will beneﬁt from high-
quality pan and ceph
images for optimized
therapy planning.
General Practitioners
will achieve greater
diagnostic accuracy
for routine cases.
“With my Sirona 3D unit, I can see the anatomy of canals, calciﬁcation, extent of resorption, frac-

tures, and sizes of periapical radiolucencies, all of which inﬂuence treatment plans for my patients.
Combine that with the metal artifact reduction software that reduces distortions from metal objects,
my treatment process is a lot less stressful. My patients beneﬁt from the technology and my
referrals appreciate the value.” ~ Dr. Kathryn Stuart, Endodontist - Fishers, Indiana
For more information, visit www.Sirona3D.com
or call Sirona at: 800.659.5977
The advantages of 2D & 3D in one comprehensive unit
ORTHOPHOS XG 3D is a hybrid system that provides clinical
workﬂow advantages, along with the lowest possible effective
dose for the patient. Its 3D function provides diagnostic accuracy
when you need it most: for implants, surgical procedures and
volumetric imaging of the jaws, sinuses and other dental anatomy.
www.facebook.com/Sirona3D
6 Endodontic
practice
Volume 7 Number 1
CORPORATE INSIGHT
A new paradigm in endodontics
“Our goal is to transform
endodontics by improving the
clinical quality and business
performance of practices
performing root canal therapy,”
said Bjarne Bergheim,
President and Chief Executive
Ofﬁcer of Sonendo.
Company History
The mission of Sonendo
®
is to lead the

transformation of endodontics through
Sound Science
®
. At its core, Sound Science
means that we are committed to ensuring
that our product development is based on
sound scientiﬁc research, and extensive
proof source. Furthermore, we will continue
to leverage our innovative approach to
sound — and its use in endodontics —
as we work to bring this disruptive new
technology to the endodontic community.
Sonendo is a privately held company
located in Laguna Hills, California, and
employs over 50 people. Sonendo was
founded in 2006 with co-founders who
include director Olav Bergheim; California
Institute of Technology professor Morteza
Ghari; retired dentist Erik Hars; and Bill
Nieman. As President and CEO, Bjarne
Bergheim collaborates with a scientiﬁc
advisory board that includes Scott Arne,
DDS, FAGD; Gerald Glickman, DDS;
Markus Haapasalo, DDS, PhD; and Ove
Peters, DMD, MS, PhD.
So·nen·do: a revolutionary company that aims to redeﬁne and transform
traditional root canal therapy.
SEM showing apical cleaning with
Sonendo’s Ultracleaning
™

System
SEM showing dentin tubules cleaned with
Sonendo’s Ultracleaning
™
System
SEM showing dentin tubules cleaned with
Sonendo’s Ultracleaning
™
System
Multisonic Ultracleaning
™
The Multisonic Ultracleaning System,
currently scheduled to debut at the 2014
AAE Annual Session, is designed to be a
disruptive technology that uses a mixture
of irrigating ﬂuids and sound waves to
clean inside the roots of teeth. It quickly,
easily, and safely loosens and removes
all the pulp tissue, debris, decay, and
bacteria from the entire root canal system
within minutes. The system is designed
to automatically and simultaneously clean
all canals in about 5 minutes, as well as
improve the clinical quality and business
performance of root canal therapy.
New paradigm
Sonendo’s design goals allow for little to no
traditional instrumentation (endodontic ﬁle)
required, with procedure time dramatically
reduced. The Multisonic Ultracleaning

System does not remove structural dentin,
preserving the structural integrity of the
tooth. Sonendo is focused to bring to
market a device that will provide an end-
odontic treatment that is highly predictable
for every procedure, more comfortable for
the patient, faster and more efﬁcient for the
practice, offering a signiﬁcant cleaner and
disinfected treatment area compared to
current standards.
Sonendo’s system is not yet commer-
cially available for sale or distribution.
For more information, visit
www.sonendo.com.
This information was provided by Sonendo.
EP
CLINICAL
Volume 7 Number 1 Endodontic
practice
7
Introduction
A key factor affecting the success of
endodontic treatment is the establishment
of an accurate root canal working
length. The ideal cleaning, shaping, and
disinfection of the root canal system
depends on the accurate determination of
the root canal anatomy from canal oriﬁce to
the canal-dentinal-cement (CDC) junction.
The apical anatomy of root canals has been

investigated in several research studies
and review articles (Kuttler, 1955; Ricucci,
1998; Green, 1956; Pineda, Kuttler, 1972).
The apical CDC junction, also deﬁned
as the minor diameter, is the anatomical
landmark that segregates the pulp tissue
from periodontal tissues. Dummer, et al.,
described the morphological variations
of apical CDC junctions in 1984. Many
of these variations cannot be determined
radiographically. The distance between the
major diameter and the minor diameter of
the apex can vary, but usually it is between
0.5 mm to 1 mm (Ricucci, 1998; Green,
1956; Pineda, Kuttler 1972).
To preserve the vitality of the periapical
tissues, the ideal cleaning, shaping, and
root canal ﬁlling materials have to be limited
to the apical CDC junction. Therefore, it
has become the preferred landmark for
the apical endpoint for root canal therapy
(Nekoofar, et al., 2002).
Procedural errors — such as over-
instrumentation or under-instrumentation —
can occur because of inaccurate estimates
of root canal length. Over-instrumentation
can damage the anatomy of the root end
and also injure the periodontal tissues. On
the other hand, under-instrumentation may
create a suitable environment for bacteria

that might cause a less favorable outcome
of the endodontic treatment. Therefore,
the accurate determination of the working
length is an important goal for the success
of the root canal treatment. Several
methods can be used to measure the root
canal working length.
Radiographs can visualize the root
canal but are limited to two dimensions and
are technique-sensitive to operator inputs
(Cox, et al., 1991). A study by Brunton,
et al., (2002) showed that electronic apex
locators (EALs) could be used to reduce
the radiation exposure time to the patients
by requiring less radiographs. Some
studies found that there were no signiﬁcant
differences between the accuracy of EALs
and radiographs (Hoer, Attin, 2004; Vieyra,
Acosta, 2011). A study by Real, et al.,
(2011) found that EALs were signiﬁcantly
more accurate than digital sensors.
The use of EALs for determining the
root canal working length has become an
indispensable part of endodontic treatment.
More accurate EALs have evolved in
recent years by improving the basic
principles upon which the measurements
are performed. In 1918, Custer proposed
the development of electronic devices to
determine the working length. In 1942,

Suzuki presented the ﬁrst generation of EAL
to use the electrical resistance properties
of the root canal to determine its working
length. Sunada (1962) determined the
electrical resistance value constantly at 6.5
ohms. This theory considered the electrical
resistance between the oral tissues and the
periodontal ligament to remain constant.
The second generation of EAL had
the peculiarity of working with impedance
principles. An example of the third-
generation EAL is the Root ZX
®
(J. Morita)
which worked with a constant frequency
principle. A fourth-generation EAL was
created by Gordon and Chandler (2004),
which worked with multiple frequencies.
The ﬁrst version of Root ZX EAL
used the average measurements of
two frequencies of 0.4kHz and 8kHz.
Kobayashi and Suda (1994) described
this method as the EAL frequency ratio.
The most recent version of Root ZX uses
multiple frequencies and can be classiﬁed
as a fourth-generation EAL (Kobayashi,
Suda, 1994).
The ﬁfth generation of EAL also
uses multiple frequencies, in addition to
calculating the root mean square (RMS)

values of the electric signals. The RMS
represents the energy of the electric
signals, and therefore, it is claimed to
be less affected by electrical noises
affecting other physical parameters such
as amplitude or phase of electrical signal
that are used by other EALs. An example
of a ﬁfth-generation EAL is the Propex
Pixi
™
, which is a newer version of recently
designed EAL Propex (Dentsply Maillefer,
Switzerland).
Accuracy of a new apex locator in ex-vivo teeth using
scanning electron microscopy
Drs. Maria Bonilla, Taner Cem Sayin, Brenda Schobert, and Patrick Hardigan compare the accuracy of root
canal working lengths in 200 ex-vivo teeth determined using a fourth-generation electronic apex locator
and a new ﬁfth-generation electronic apex locator
Figure 1: Apical portion of the specimen
Maria Bonilla, DDS, CAGS, works at the Department of
Endodontics, Nova Southeastern University, College of
Dental Medicine, Fort Lauderdale, Florida.
Taner Cem Sayin, DDS, PhD, is an associate professor
at the Department of Endodontics, Nova Southeastern
University, College of Dental Medicine, Fort Lauderdale,
Florida.
Brenda Schobert, DDS, CAGS, works at the Department
of Endodontics, Nova Southeastern University, College
of Dental Medicine, Fort Lauderdale, Florida.
Patrick C. Hardigan, PhD, is a professor of public health

at the Department of Endodontics, Nova Southeastern
University, College of Dental Medicine, Fort Lauderdale,
Florida.
8 Endodontic
practice
Volume 7 Number 1
CLINICAL
Aims and objectives
The aim of this study was to compare the
accuracy of root canal working lengths
in 200 ex-vivo teeth determined using a
fourth-generation EAL (the Root ZX II) with
a ﬁfth-generation EAL (the Propex Pixi).
The Propex Pixi and Root ZX II use signals
at two different frequencies to calculate
the ﬁle tip position relatively to root apex.
Furthermore, the technology utilized in
Propex Pixi differs from the technology used
in Root ZX II: Propex Pixi by measuring the
RMS of the electric signal, which is further
used for calculations. Because of these
technology differences, there is a need to
compare the accuracy of the Propex Pixi
with the Root ZX II to determine root canal
working lengths.
Materials and methods
After IRB approval was obtained, an
archive of 200 sound human permanent
teeth with completely formed apices
was used in this study. The teeth were

disinfected by submerging them in a 6%
sodium hypochlorite (NaOCl) solution
for 15 minutes. They were then rinsed
for 10 minutes with distilled water. This
disinfection cycle was repeated 3 times for
each tooth. The teeth were stored in 20-
ml sterile scintillation vials ﬁlled with distilled
water in a refrigerator at 5ºC until use.
Prior to inclusion in this study, the root
surfaces and apices of each tooth were
examined under x16 magniﬁcation using
a surgical microscope (Global Surgical
Corp.) for a possible fracture or resorptive
areas. If any defects were observed in a
tooth, it was discarded from this study. The
outer surfaces of the teeth were cleaned
by removing tissues with a 15c scalpel
(Aspen Surgical). Photographs were taken
of each tooth in a buccolingual as well
as a mesiodistal view (Figure 1). Digital
radiographs (Schick Technologies) for each
tooth in a buccolingual and a mesiodistal
direction were also taken as pre-operatory
procedure (Figure 2).
Access cavities were prepared with
a high-speed handpiece and a ﬁssure bur
(Maillefer, Switzerland) with water coolant,
under the surgical operating microscope.
Pre-ﬂaring of the root canals was not
performed. The root canals were irrigated

with 6% NaOCl before the introduction
of any ﬁle. Patency was established by
introducing a No. 6 or No. 8 hand ﬁle
(Maillefer, Switzerland) until it emerged
in the apical foramen, and this was
corroborated by visualization using the
surgical microscope. Each of the teeth was
embedded in a dental device for training
purposes with alginate. The 200 teeth were
randomly assigned to the Propex Pixi (n =
100) group or the Root ZX II (J. Morita) (n =
100) group.
The root canal working length
measurements were carried out according
to the manufacturers’ instructions. The lip
clip electrode was attached to the device,
and the other electrode was attached to
a ﬁle that ﬁt snugly in the apical portion of
the root canal. Digital radiographs for each
tooth in a buccolingual and a mesiodistal
direction were taken to corroborate
radiographically that the working length
had been established. The ﬁles were then
withdrawn from the canals to measure
them with an endodontic ruler (Maillefer,
Switzerland). The reference points were
marked with silicone stoppers. All the
working lengths were measured using
the same endodontic ruler. The working
lengths were recorded on a spreadsheet.

The ﬁles were reinserted into the
root canal and cemented with a ﬂowable
composite resin to avoid any movements
from within the root canal. The apical 4-mm
portion of the root canals was carefully
shaved in a longitudinal direction using a
ﬁne diamond bur (Maillefer, Switzerland)
and a scalpel under a Olympus SZX7
®

stereomicroscope at x8 magniﬁcation to
prevent touching the ﬁles with the diamond
bur.
The apical portion of the teeth and
ﬁles were observed in micrographs at x40
magniﬁcation using an FEI Quanta 200
FEG Environmental Scanning Electron
Microscope in the low-vacuum mode, and
the distance from the ﬁle tip to the CDC
junction was measured with Scandium
image software (FEI Company) (Figure
3). A Welch’s t-test test was used to
compare the accuracy of the working
lengths determined by the two EALs at a
signiﬁcance level of P<.05.
Results
The mean distance from the ﬁnal working
length to the ﬁle tip was 0.21 ± 0.25 mm for
the Propex Pixi EAL while it was 0.08 ± 0.22
mm for the Root ZX II EAL (Table 1, Figure

2). A difference of 0.13 mm (95%: 0.23 to
0.47) was found between the Propex Pixi
and Root ZX II EALs. The Propex Pixi was
accurate 88% of the time to ± 0.5 mm and
98% accurate within ± 1.00 mm (Table
2). The Root ZX II was accurate 97% of
the time to ±0.50 mm and 99% accurate
within ±1.00 mm (Table 2). There was no
signiﬁcant difference in the accuracy of the
working lengths determined by the two
EALs (P > 0.05).
Discussion
This study is the ﬁrst to investigate the
accuracy of the root canal working length
measurements of a new ﬁfth-generation
EAL called the Propex Pixi. Given the
importance of accurate root canal working
length measurements to the outcome of
Figure 2: The mean distance from the ﬁnal working length to the ﬁle tip
CLINICAL
Volume 7 Number 1 Endodontic
practice
9
endodontic treatment, it is essential that all
new EALs be evaluated for their accuracy.
The multiple frequency processing
technology, and use of RMS incorporated
into the Propex Pixi may have theoretical
advantages for increasing the accuracy
of the working length measurements, by

reducing the electrical noises affecting
other physical parameters like amplitude
or phase of electrical signal that are
used by other EALs. But the technology
improvements were not enough to make
the Propex Pixi signiﬁcantly more accurate
than the Root ZX II (P > 0.05), which
appears to be an extremely accurate
fourth-generation EAL.
The Propex Pixi and Root ZX II gave
root canal working lengths of 0.21 and
0.08 mm, which were accurate 88% and
97% of the time within 0.5 mm of the
actual root canal length. These high levels
of accuracy appear to be beneﬁcial to the
practice of endodontics, and since both
EALs had similar levels of accuracy, both
the Propex Pixi and Root ZX II EALs can be
recommended for use in endodontics.
Traditionally, a radiographic evaluation
has been the primary technique to determine
the vertical limit of instrumentation, irrigation,
and obturation in endodontic therapy
(Fouad, Rivera, Krell, 1993). However,
El Ayouti, et al., (2005) concluded that
radiographic evaluation was not accurate
enough and causes over-instrumentation,
especially in 56% of premolars. Williams,
et al., (2006) concluded that the ﬁles that
seem to be beyond the apex were longer

by an average of 1.2 mm. In contrast, ﬁles
that seemed to be short of the apex on the
radiographs were 0.47 mm closer to the
apical foramen.
The new technologies in EALs appear
to make them more accurate; they are more
accurate than radiographs, which are only
useful to corroborate the EAL readings.
Radiographs are useful for visualizing the
existence of pathology, the amount of root
to treat, and the direction of curvatures
in the root canal system (Ricucci, 1998;
Dummer, McGinn, Rees, 1984; Gordon,
Chandler, 2004). The use of EAL reference
points has been controversial. The major
diameter reference point has been claimed
as the more reliable and accurate reference
point than minor diameter because the
minor reference point is more difﬁcult to
locate (Martinez-Lozano, et al., 2001;
Lee, et al., 2002). Lee, et al., (2002)
recommended using the major foramen
as reference point to determine the
accuracy of EALs. The anecdotal evidence
suggests it is extremely important to follow
manufacturers’ EAL instructions without
any deviation and to always have a high
battery charge. Some previous studies
discovered that EALs can only detect
the major foramen (Mayeda, et al., 1993;

Ounsi, Naaman, 1999). Therefore, the
present study used the CDC junction as
the measuring point for both EALs.
The Propex Pixi is a new EAL, and
no literature is available to compare its
working length accuracy with the present
study. The results of the present study did
demonstrate that it has a similar accuracy
to the Root ZX II. The accuracy of the Root
ZX II has been successful to determine
the root canal working length within 1
mm in 96.5% of the cases observed by
Shabahang, et al., (1996). The accuracy
of the Root ZX II was conﬁrmed in a study
by Pagavino (1998), which had an 82.75%
success in locating the root canal working
length with a 0.5 mm tolerance. In a study
by El Ayouti (2005), the Root ZX II also
showed 90% accuracy within a 1 mm
range when compared to Raypex
®
(VDW)
(74%) and Apex Pointer
™
(Micro-Mega)
(71%).
Welt, et al., (2003) also found that Root
ZX II was 90.7% accurate within 0.5 mm at
the apical constriction. An in-vivo study by
Silveira, et al., (2011) found that the Root

ZX II was 91.7% accurate in locating the
apical constriction. On the other hand,
percentages for accuracy in Tselnik’s 2005
study were around 75% for Root ZX. The
ﬁrst generation of Propex also showed
Group N M (mm) SD (mm) Min (mm) Max (mm)
PIXI 100 0.21 0.25 -0.40 1.27
Root ZX 100 0.08 0.22 -0.87 1.04
Difference NA 0.13 0.03 0.23 0.47
Table 1: Descriptive statistics per locator device
PIXI (N=100) Root ZX (N=100)
Distance from actual WL Count Percent Count Percent
-0.49 to 0.00 8 8% 13 13%
0.01 to 0.50 80 80% 84 84%
0.50 to 1.00 10 10% 2 2%
Greater then 1.00 2 2% 1 1%
Table 2: Frequency of distance from working length per locater device
10 Endodontic
practice
Volume 7 Number 1
CLINICAL
REFERENCES
Brunton PA, Abdeen D, MacFarlane TV. The effect
of an apex locator on exposure to radiation during
endodontic therapy. J Endod. 2002;28(7):524-526.
Cox VS, Brown CE Jr, Bricker SL, Newton CW.
Radiographic interpretation of endodontic ﬁle length.
Oral Surg Oral Med Oral Pathol. 1991;72(3):340-344.
Custer LE. Exact methods of locating the apical
foramen. J Natl Dent Assoc. 1918;5:815-819.

Dummer PM, McGinn JH, Rees DG. The position and
topography of the apical canal constriction and apical
foramen. Int Endod J. 1984;17(4):192-198.
ElAyouti A, Kimionis I, Chu AL, Löst C. Determining the
apical terminus of root-end resected teeth using three
modern apex locators: a comparative ex vivo study. Int
Endod J. 2005;38(11):827-833.
Fouad AF, Rivera EM, Krell KV. Accuracy of the Endex
with variations in canal irrigants and foramen size. J
Endod. 1993;19(2):63-67.
Gordon MP, Chandler NP. Electronic apex locators. Int
Endod J. 2004;37(7):425-437.
Green D. A stereomicroscopic study of the root apices
of 400 maxillary and mandibular anterior teeth. Oral
Surg Oral Med Oral Pathol. 1956;9(11):1224-1232.
Haffner C, Folwaczny M, Galler K, Hickel R. Accuracy
of electronic apex locators in comparison to actual
length – an in vivo study. J Dent. 2005;33(8):619-625.
Herrera M, Abalos C, Planas AJ, Llamas R. Inﬂuence of
apical constriction diameter on Root ZX apex locator
precision. J Endod. 2007;33(8):995-998.
Hoer D, Attin T. The accuracy of electronic working
length determination. Int Endod J. 2004;37(2):125-131
Kaufman AY, Keila, S, Yoshpe M. Accuracy of a
new apex locator: an in vitro study. Int Endod J.
2002;35(2):186-192.
Kobayashi C, Suda H. New electronic canal measuring
device based on the ratio method. J Endod.
1994;20(3):111-114.
Kuttler Y. Microscopic investigation of root apexes. J

Am Dent Assoc. 1955;50(5):544-562.
Lee SJ, Nam KC, Kim YJ, Kim DW. Clinical accuracy
of a new apex locator with an automatic compensation
circuit. J Endod. 2002;28(10):706-709.
Martínez-Lozano MA, Forner-Navarro L, Sánchez-
Cortés JL, Llena-Puy C. Methodological considerations
in the determination of working length. Int Endod J.
2001;34(5):371-376.
Mayeda DL, Simon JH, Aimar DF, Finley K. In vivo
measurement accuracy in vital and necrotic canals with
the Endex apex locator. J Endod. 1993;19(11):545-548.
Nekoofar MH, Sadeghi K, Sadighi Akha E, Namazikhah
MS. The accuracy of the Neosono Ultima EZ apex
locator using ﬁles of different alloys: an in vitro study. J
Calif Dent Assoc. 2002;30(9):681-684.
Ounsi HF, Naaman A. In vitro evaluation of the reliability
of the Root ZX electronic apex locator. Int Endod J.
1999;32(2):120-123.
Pagavino G, Pace R, Baccetti T. A SEM study of in
vivo accuracy of the Root ZX electronic apex locator. J
Endod. 1998;24(6):438-441
Plotino G, Grande NM, Brigante L, Lesti B, Somma F.
Ex vivo accuracy of three electronic apex locators: Root
ZX, Elements Diagnostic Unit and Apex Locator and
ProPex. Int Endod J. 2006;39(5):408-414.
Pineda F, Kuttler Y. Mesiodistal and buccolingual
roentgenographic investigation of 7,275 root canals.
Oral Surg Oral Med Oral Pathol. 1972;33(1):101-110.
Real DG, Davidowicz H, Moura-Netto C, Zenkner Cde
L, Pagliarin CM, Barletta FB, de Moura AA. Accuracy of

working length determination using 3 electronic apex
locators and direct digital radiography. Oral Surg Oral
Med Oral Pathol Oral Radiol Endod. 2011;111(3):e44-49
Ricucci D. Apical limit of root canal instrumentation
and obturation, part I. Literature-review. Int Endod J.
1998;31(6):384-393.
Shabahang S, Goon WW, Gluskin AH. An in vivo
evaluation of Root ZX electronic apex locator. J Endod.
1996;22(11):616-618.
Silveira LF, Petry FV, Martos J, Neto JB. In vivo
comparison of the accuracy of two electronic apex
locators. Aust Endod J. 2011;37(2):70-72.
Sunada I. New method for measuring the length of the
root canal. J Dent Res. 1962;41:375-387.
Suzuki K. Experimental study on iontophoresia. J Jap
Stomatol. 1942;16:411.
Tselnik M, Baumgartner JC, Marshall JG. An evaluation
of Root ZX and elements diagnostic apex locators. J
Endod. 2005;31(7):507-509.
Vieyra JP, Acosta J. Comparison of working length
determination with radiographs and four electronic
apex locators. Int Endod J. 2011;44(6):510-518.
Welk AR, Baumgartner JC, Marshall JG. An in vivo
comparison of two frequency-based electronic apex
locators. J Endod. 2003;29(8):497-500.
Williams CB, Joyce AP, Roberts S. A comparison
between in vivo radiographic working length
determination and measurement after extraction. J
Endod. 2006;32(7):624-627.
similar accuracy for determining the apical

constriction with Root ZX II in Plotino’s
(2006) study. The accuracy of the Root ZX
II measurement to within 0.50 mm of the
root canal working length 97% of time, and
within 1 mm 99% of the time in the present
study, appears consistent with previous
research. Some of the accuracy variations
may be due to differences in operator
technique sensitivity, handling of the
EALs, placement of ﬁles, and radiographic
angulation visualization of the ﬁle inside the
root canal.
Stainless-steel hand ﬁles were used
in the present study. The ﬁle sizes were
different in each root canal because of
differences in root canal sizes. According
to Herrera (2007), the Root ZX II EAL is
more accurate if the diameter size of the
ﬁle is less than a No. 60 (0.6 mm). The
largest apical ﬁle diameter used in the
present study was 0.30 mm. Shaving the
apical portion of the canal also gave a clear
visibility of the CDC junction, and it seemed
to allow more accurate measurements
from radiographs using the SEM.
The results of the present study
suggest that our improvements to the
methodology for measuring working length
accuracy can help improve the reliability of
EALs — in the case of the Root ZX II, up to

99% of the time within 1 mm. Root canal
irrigation with 6% NaOCl was used in the
present study to dissolve the necrotic pulp
around the oriﬁce and the coronal portion
of the canals before determining the
working lengths. The antimicrobial activity
and the removal of the organic remnants
by irrigants are very important for the
success of endodontic treatment. Previous
studies showed that some EALs had
inaccurate measurements when used with
other irrigation solutions (Kaufman, Keila,
Yoshpe, 2002; Haffner, et al., 2005). The
present study conﬁrmed that both EALs
can provide accurate measurements in the
presence of 6% NaOCl. We recommend
further modiﬁcation of EALs to select the
type and dilution of irrigation solutions to
avoid this problem, and to help improve
the accuracy of EALs under all types of
operating conditions. While using the
Propex Pixi, we did appreciate its smaller
size compared to traditional sized EALs;
this gave a little more space in the clinical
setup.
Conclusions
The multiple frequency processing tech-
nology and the use of RMS incorporated
into the Propex Pixi may have theoretical
advantages for increasing the accuracy of

the working length measurements. But the
technology improvements were not enough
to make the Propex Pixi signiﬁcantly more
accurate than the Root ZX II (P > 0.05),
which appears to be an extremely accurate
fourth-generation EAL. These high levels
of accuracy appear to be beneﬁcial to the
practice of endodontics, and since both
EALs had similar levels of accuracy, both
the Propex Pixi and Root ZX II EALs can be
recommend for use in endodontics.
Acknowledgments
The authors thank Dr. Armando Lara from
University of Tlaxcala, Mexico.
EP
Introduction
According to Bird, Chambers, and
Peters (2009), rotary nickel-titanium (NiTi)
instruments have become a standard
tool for shaping root canal systems.
These instruments provide the clinician
with several advantages compared to
conventional stainless steel instruments.
They are more ﬂexible, have increased
cutting efﬁciency (Kim, et al., 2012; Peters,
2004; Walia, Brantley, Gerstein, 1988), can
create centered preparations more rapidly
(Short, Morgan, Baumgartner, 1997;
Glossen, et al., 1995), and can produce

tapered root canal preparations with a
reduced tendency of canal transportation
(Chen, Messer, 2002; Kim, et al., 2012).
However, nickel-titanium instruments
appear to have a high risk of fracture
(Arens, et al., 2003; Sattapan, et al., 2000)
mainly because of ﬂexural and torsional
stresses during rotation in the root canal
system (Berutti, et al., 2003; Parashos,
Messer, 2006). When there is a wide area
of contact between the cutting edge of
the instrument and the canal wall during
rotation, the instrument will be subjected to
an increase in torsional stress (Peters, et al.,
2004; Blum, et al., 1999). The preparation
of a reproducible glide path can reduce the
torsional stress on root canal instruments.
A glide path is a smooth passage that
extends from the canal oriﬁce in the pulp
chamber to its opening at the apex of
the root (West, 2006). This will provide a
continuous, uninterrupted pathway for
the rotary nickel-titanium instrument to
enter and to move freely to the root canal
terminus.
The main purpose of a glide path is to
create a root canal diameter the same size
as, or ideally a size bigger than, the ﬁrst
rotary instrument introduced (Berutti, et al.,
2004; Varela-Patio, et al., 2005; Berutti, et

al., 2009). Another way to reduce torsional
stress is to incorporate multiple progressive
tapers to the instrument design, for
example, the ProTaper
®
universal system
(Dentsply/Maillefer). According to West
(2001), the progressive taper allows for
only small areas of dentin to be engaged.
This design concept also contributes to
maintaining the original canal curvature
(Yun, Kim, 2003).
ProTaper Next
Recently, the ProTaper Next system
(Dentsply/Maillefer) was launched into
the dental market. (ProTaper NEXT
®
is
only available in North America through
DENTSPLY Tulsa Dental Specialties.)
There are ﬁve instruments in the system,
but most canals can be prepared by using
only the ﬁrst two instruments. This system
also makes use of the multiple progressive
taper concept. Each ﬁle presents with an
increasing and decreasing percentage
tapered design on a single ﬁle concept
(Ruddle, Machtou, West, 2013). The design
ensures that there is reduced contact
between the cutting ﬂutes of the instrument

and the dentin wall, thus reducing the
chance for taper lock (screw-in effect). At
the same time, it also increases ﬂexibility
and cutting efﬁciency (Ruddle, 2001).
The ﬁrst instrument in the system
is ProTaper Next X1 (Figure 1), with a tip
size of 0.17 mm and a 4% taper. This
instrument is used after creation of a
reproducible glide path by means of hand
instruments or rotary PathFile
™
instruments.
This instrument is always followed by the
second instrument, the ProTaper Next
X2 (0.25 mm tip and 6% taper) (Figure 2).
ProTaper Next X2 can be regarded as the
ﬁrst ﬁnishing ﬁle in the system, as it leaves
the prepared root canal with adequate
shape and taper for optimal irrigation and
root canal obturation. ProTaper Next X1
and X2 have an increasing and decreasing
percentage tapered design over the active
portion of the instruments.
The last three ﬁnishing instruments
are ProTaper Next X3 (0.30 mm tip with
7% taper) (Figure 4), ProTaper Next X4
(0.40 mm tip with 6% taper) (Figure 5) and
ProTaper Next X5 (0.5 mm tip with 6%
taper) (Figure 6). These instruments have a
decreasing percentage taper from the tip

to the shank. ProTaper Next X3, X4, and
X5 can be used to either create more taper
in a root canal or to prepare larger root
canal systems.
Another beneﬁt of this system is the
fact that the instruments are manufactured
from M-Wire and not traditional nickel-
titanium alloy. Research by Johnson, et
al., (2008) demonstrated that the M-Wire
alloy could reduce cyclic fatigue by
400% compared to similar instruments
manufactured from conventional nickel-
titanium alloys. The added metallurgical
beneﬁt contributes toward more ﬂexible
instruments, increased safety, and
Clinical guidelines for the use of ProTaper Next
™

instruments: part one
12 Endodontic
practice
Volume 7 Number 1
CLINICAL
Drs. Peet J. van der Vyver and Michael J. Scianamblo discuss the clinical guidelines for using
Protaper Next instruments
Figure 1: ProTaper Next X1 (17/04) instrument
Dr. Peet J. van der Vyver is extraordinary professor at
the Department of Odontology, School of Dentistry,
University of Pretoria and Private Practice, Sandton,
South Africa (see www.studio4endo.com for more).

Michael J Scianamblo, DDS, is an endodontist and
the developer of Critical Path Technology. He is a
postgraduate and fellow of the Harvard School of Dental
Medicine and has served as a faculty member of the
University of the Paciﬁc and the University of California,
Schools of Dentistry in San Francisco.
Figure 2: ProTaper Next X2 (25/06) instrument
Figure 3: ProTaper Next X3 (30/07) instrument
Figure 4: ProTaper Next X4 (40/06) instrument
Figure 5: ProTaper Next X5 (50/06) instrument
CLINICAL
Volume 7 Number 1 Endodontic
practice
13
protection against instrument fracture
(Gutmann, Gao, 2012).
The last major advantage towards
root canal preparation with the ProTaper
Next system is the fact that most of
the instruments present with a bilateral
symmetrical rectangular cross section
(Figure 6) with an offset from the central
axis of rotation (except in the last 3 mm
of the instrument, D0-D3). The exception
is ProTaper X1 that has a square cross
section in last 3 mm to give the instruments
a bit more core strength in the narrow
apical part.
This design characteristic allows
the instrument to experience a rotational

phenomenon known as precession or
swagger (Scianamblo, 2011). The beneﬁts
of this design characteristic include:
• It further reduces (in addition to the
progressive tapered design) the
engagement between the instrument
and the dentin walls. This will contribute
to a reduction in taper lock, screw-in
effect, and stress on the ﬁle.
• Removalofdebrisinacoronaldirection
(Figure 7) because the off-center cross
section allows for more space around
the ﬂutes of the instrument. This will
lead to improved cutting efﬁciency, as
the blades will stay in contact with the
surrounding dentin walls. Root canal
preparation is done in a very fast and
effortless manner.
• Theswaggeringmotionoftheinstrument
initiates activation of the irrigation solution
during canal preparation, improving
debris removal.
• Itreducestheriskofinstrumentfracture
because there is less stress on the ﬁle
and more efﬁcient debris removal.
• Everyinstrumentiscapableofcuttinga
larger envelope of motion (larger canal
preparation size) (Figure 6) compared
to a similarly sized instrument with a
symmetrical mass and axis of rotation.

This allows the clinician to use fewer
instruments to prepare a root canal to
adequate shape and taper to allow for
optimal irrigation and obturation.
• Thereisasmoothtransitionbetweenthe
different sizes of instruments because
the design ensures that the instrument
sequence itself expands exponentially.
Clinical guidelines for ProTaper
Next instruments
The clinical technique for ProTaper Next
will be discussed by means of case reports.
The ﬁrst case report will outline the basic
guidelines for the use of ProTaper Next
instruments.
The patient, a 46-year-old male,
presented with a previous emergency
root canal treatment on his upper-left ﬁrst
premolar. A periapical radiograph showed
evidence of three separate roots and large
periapical lesion (Figure 8). According to
the patient, the tooth was left open by
his previous dentists that performed the
emergency root canal treatment to allow
for drainage.
Guideline one: Create straight-
line access and remove triangles
of dentin
It is very important to prepare an adequate
access cavity that will ensure straight-

line access into each root canal system.
However, in the present clinical case there
was still a dentin triangle obscuring direct
access into the distobucaal root canal
system (Figures 9A and 9B). The Start-X
tip No. 3 (Dentsply/Maillefer) was used to
remove some of this dentin on the pulp ﬂoor
Figure 6: ProTaper Next instruments have a bilateral
symmetrical rectangular cross section (except for the
last 3 mm of X1) with an offset from the central axis of
rotation (except in the last 3 mm of all the instruments,
D0-D3). This design characteristic allows the instrument
to experience a rotational phenomenon known as
precession or swagger. The swaggering movement
enables the instrument to cut a larger envelope of motion
(red line) compared to a similarly sized instrument with a
symmetrical mass and axis of rotation
Figure 7: ProTaper Next instrument after canal preparation
to full working length. Note the absence of debris on the
cutting ﬂutes in the last 2-3 mm of the instrument. In the
presence of irrigation solution, the cutting debris is moved
coronally, away from the tip of the instruments because
of the swaggering effect allowing more space for ﬂuid
movement in the root canal system
Figure 8: Preoperative radiograph of maxillary left ﬁrst
premolar with three roots, showing a large periapical
radiolucency
Figures 9A-9B: Extended access cavity preparation to allow straight-line access into the buccal and palatal root
canals. Arrows indicate dentin triangle obscuring the oriﬁce of the distobuccal root canal
(Figure 10), allowing more direct access to

the distobuccal root canal oriﬁce.
A Micro-opener (Dentsply/Maillefer),
size 10, 06% taper instrument was used
to locate and enlarge the distobuccal
and mesiobuccal canal oriﬁces (Figure
11). For improved radicular access, the
SX instrument (Dentsply/Maillefer) from
the ProTaper Universal system was used
(Figure 12A). The recommended method of
use is to introduce the ﬁle into the coronal
portion of the root canal, ensuring that the
ﬁle is able to freely rotate. Restrictive dentin
is then removed by using a backstroke,
outward brushing motion. This step will
also relocate the canal oriﬁces more
mesial or distal (away from furcal danger)
and preﬂare the canal oriﬁces, ensuring
complete staight-line access into the root
canal system (Figure 12b).
14 Endodontic
practice
Volume 7 Number 1
CLINICAL
Guideline two: Negotiate canal to
patency and create a reproducible
glide path
The authors prefer to negotiate the root
canal with size 08 or 10 K-ﬁles until apical
patency is established (Figure 13A). Apical
patency is the ability to pass small K-ﬁles

0.5 mm - 1 mm passively through the apical
constriction, beyond the minor diameter
without widening it (Buchanan, 1989).
Length determination was done using
a Propex Pixi Apex Locator (Dentsply/
Maillefer). Predictable readings were
achieved by using two size 10 K-ﬁles in the
mesiobuccal and distobuccal root canals
and a size 20 K-ﬁle in the larger palatal
root canal and conﬁrmed radiographically
(Figure 13B).
After working length determination,
a reproducible glide path should be
established. According to West (2010),
a glide path is a smooth passage that
extends from the canal oriﬁce in the pulp
chamber to its opening at the root apex.
Most authors recommend that the glide
path should be the same size as, or ideally
a size bigger, than the ﬁrst rotary instrument
that will be introduced into the root canal
system (Berutti, et al., 2004; Varela-Patino,
et al., 2005; Berutti, et al., 2009).
It is recommended to use the stainless
steel K-ﬁles in vertical in and out motion
with an amplitude of 1 mm and gradually
increasing the amplitude as the dentin wall
wears away and the ﬁle advances apically
(West, 2006). West (2010) recommends
a “super loose” size 10 K-ﬁle as the

minimum requirement. To conﬁrm that a
reproducible glide path is present, the size
10 ﬁle is taken to full working length (Figure
14B). The ﬁle is then withdrawn 1 mm and
should be able to slide back to working
Figure 10: Start-X tip No.3
(Dentsply/Maillefer) is used to
remove some of the restrictive
dentin obscuring the distobuccal
canal
Figure 11: Micro-opener (Dentsply/Maillefer), size 10, taper 6%
is used to locate the distobuccal canal oriﬁce
Figure 12A: ProTaper
SX instrument
(Dentsply/Maillefer)
instrument is used to
create more straight-
line radicular access
Figure 12B: Direct, straight-line access
(arrows) into all three canals after
removal of coronal restrictive dentin
Figure 13A: Distobuccal root canal
negotiated to patency (arrow) with a size
10 K-ﬁle (Dentsply/Maillefer)
Figure 13B: Periapical radiograph showing
the position of the ﬁles during length
determination — two size 10 K-ﬁles (25 mm
length) in mesiobuccal and distobuccal root
canals and a size 20 K-ﬁle (25 mm length) in
palatal root canal

Figure 14: Reproducible glide path conﬁrmation. 14A: Size 10
K-File ﬁle is taken to full working length 14B: The size 10 K-ﬁle is
withdrawn 4 mm to 5 mm and slide back to working length using
light ﬁnger pressure
16 Endodontic
practice
Volume 7 Number 1
CLINICAL
length by using light ﬁnger pressure.
Thereafter, the ﬁle is withdrawn 2 mm and
should be able to slide back to working
length, using the same protocol. When the
ﬁle can be withdrawn 4 mm to 5 mm and
slide back to working length (Figure 14B),
a reproducible glide path is conﬁrmed (Van
der Vyver, 2011).
The reproducible glide path is then
enlarged using rotary PathFiles (Dentsply/
Maillefer). (PathFiles
™
are only available in
North America through DENTSPLY Tulsa
Dental Specialties.) PathFile No. 1 (0.13
mm tip size) is taken to full working length
operating at 300 rpm and 5 N/cm torque
(Figure 15A). As soon as the ﬁle reaches
working length, the authors recommend
to brush lightly outwards against one side
of the canal wall. The ﬁle is pushed back

to working length and brushed outward
against another part of the canal wall. This
procedure is repeated four times (touching
the canal wall in a mesial, distal, buccal, and
lingual direction). PathFile No. 2 (0.16 mm
tip size) is used following the same protocol
(Figure 15B). When using ProTaper Next, it
is only necessary (in most cases) to enlarge
the glide path to the second PathFile (0.16
mm) as the ﬁrst preparation instrument, the
X1 of the ProTaper Next system has a tip
size of ISO 17. However, it is recommended
to use PathFile No. 3 (0.19 mm tip size)
when dealing with challenging root canal
systems.
Guideline three: ProTaper Next
preparation sequence
ProTaper Next X1 (shaping instrument only)
Introduce sodium hypochlorite and the
ProTaper Next X1 instrument into the
root canal. The authors found that four
scenarios can present itself when using
ProTaper Next X1 instrument:
1. Easy root canals
2. More difﬁcult and longer root canals
3. Very long/severely curved root canals
4. Larger diameter root canals and
retreatment cases root canals where
the use of ProTaper Next X1 is not
necessary and canal preparation can be

initiated with ProTaper Next X2, X3, X4,
or X5.
The last two scenarios will be
discussed later in this article. For easy
canals (mesiobuccal root canal in this
case report), allow the ProTaper Next
X1 instrument (operating at 300 rpm and
torque of 2.8N/cm) to slide down the glide
path up to working length (Figure 16A). If
this is possible, pull the instrument back
to approximately 2-3 mm short of working
length and incorporate a deliberate
backstroke, outward brushing motion
(away from any external root concavities) to
create more space in the coronal aspect of
the root canal (Figure 16B). Finally, take the
ﬁle to full working length and “touch” the
apex and brush outwards (coronally) with
the ﬁle in the apical third of the root canal.
This “touch-and-brush” sequence can be
repeated up to 3 or 4 times (Figure 16C).
For more difﬁcult and longer canals
(distobuccal root canal in this case report),
allow the ProTaper Next X1 to slide down
the glide path until resistance is met (Figure
17A). Incorporate a deliberate backstroke,
outward brushing motion in order to remove
Figure 15A: PathFile No. 1 is taken
to full working length
Figure 15B: PathFile No. 2 is taken

to full working length
Figures 16A-16C: Preparation sequence for easy canals. 16A: ProTaper Next X1 (operating at 300
rpm and torque of 2.8N/cm) is slid down the glide path, and it is able to reach working length 16B:
The instrument is pulled back to approximately 2 to 3 mm short of working length and a deliberate
backstroke, outward brushing motion is incorporated (away from any external root concavities) to
create more space in the coronal aspect of the root canal. 16C: Finally, the instrument is taken to full
working length and a “touch-and-brush” sequence is done up to 3 to 4 times in order to complete
canal preparation
Figures 17A-17C: Preparation sequence for more difﬁcult or longer canals. 17A: Allow the ProTaper
Next X1 to slide down the glide path until resistance is met. Incorporate a deliberate backstroke,
outward brushing motion in order to remove restrictive dentin at this level. 17B: Increased lateral
space will enable the ﬁle to slide a few more mm down the root canal toward working length and the
brushing cycle is repeated. 17C: When the ﬁle reaches full working length, the “touch-and-brush”
sequence is done 3 to 4 times to complete canal preparation
CLINICAL
Volume 7 Number 1 Endodontic
practice
17
restrictive dentin at this level (away from
any external root concavities). This motion
will create more lateral space, enabling the
ﬁle to slide a few more millimeters down the
root canal towards working length (Figure
17B) (if the ﬁle ceases to progress apically,
remove the ﬁle, clean the ﬂutes, irrigate,
recapitulate, and re-irrigate the canal before
you progress with the shaping procedure).
The above procedure is repeated until the
ﬁle reaches full working length. Finally,
take the ﬁle to full working length (Figure

17C) and the “touch-and-brush” sequence
is done 3 to 4 times in order to complete
canal preparation.
After the use of ProTaper Next X1, it
is recommended to irrigate with sodium
hypochlorite, recapitulate with a small
patency ﬁle to dislodge cutting debris, and
to re-irrigate to ﬂush out all the dislodged
debris from the root canal (Figure 18).
ProTaper Next X2 (ﬁrst ﬁnishing
instrument)
Use ProTaper Next X2 (25/06) to full
working length, using the same protocol
as previously described. However, it is
recommended to use the “touch-and-
brush” sequence in the apical part of the
root canal only 2 to 3 times as a ﬁnal step
(Figure 19). Excessive “touch-and-brush”
sequences in the apical part of the root
canal can lead to transportation of the root
canal. The root canal is again irrigated,
recapitulated, and re-irrigated.
Gauging of apical foramen to
determine if the preparation is
complete
Introduce a size 25/02 NiTi hand ﬁle
(Dentsply/Maillefer) to full working length
(Figure 20). If the ﬁle is snug at working
length, it means that the apical foramen is
prepared to a size ISO 25, and the canal is

adequately shaped.
The palatal root canal in the present
case report was prepared with the
ProTaper Next X1 and X2 according to the
protocol previously outlined. In this case
it was found that the 25/02 NiTi hand ﬁle
was ﬁtting loose at length, and it could
be pushed past working length (Figure
21A) after canal preparation with the X2
instrument. This indicated that the apical
foramen was still larger than 0.25 mm. In
these situations, it is recommended to
gauge the foramen with a size 30/02 NiTi
hand ﬁle (Figure 21B). If the 30/02 ﬁle is
snug at length, the shape is complete. If it
is found that the 30/02 instrument ﬁts tight,
Figure 18: Irrigation solution is deposited into the root canal before a patency ﬁle is used to
dislodge any debris inside the root canal. Finally, the dislodged debris is ﬂushed out with fresh
irrigation solution
Figure 19: ProTaper Next X2 is taken
to full working length. The apical part
of the root canal is prepared by using
the “touch-and-brush” sequence
only 2 to 3 times with this instrument
Figure 20: Size 25/02 NiTi hand ﬁle
(Dentsply/Maillefer) is used to gauge the
apical foramen of the prepared distobuccal
root canal. Note that the ﬁle ﬁts snug up to
the full working length
Figure 21A: Size 25/02 NiTi

hand ﬁle is used to gauge the
apical foramen of the prepared
palatal root canal. In this case
it was found that the 25/02 ﬁle
was loose at length, and it could
be pushed past working length
(arrow)
Figure 21B: A size 30/02 NiTi
hand ﬁle that ﬁt snug at working
length, conﬁrmed that the shape
is complete
Figure 22A: A 30/02 NiTi hand
instrument ﬁt tight and short of
the full working length (arrow)
Figure 22B: Continue shaping
with a ProTaper Next X3 (30/07)
to full working length
Figure 22C: Gauge again with a
30/02 NiTi hand instrument. If
the instrument ﬁts tight and at
full working length, the shape is
complete
18 Endodontic
practice
Volume 7 Number 1
CLINICAL
but short of the full working length (Figure
22A), it is recommended to continue canal
preparation with the ProTaper Next X3
(30/07) (Figure 22B) and gauge again with

the 30/02 NiTi hand instrument (Figure
22C).
Guideline four: Shaping recom-
mendations for ProTaper Next X3,
X4, and X5
ProTaper Next X3 (and X4 and X5 if
necessary) is used in the same manner as
ProTaper X1 or X2 with the exception that
the apical preparation is done by using the
“touch-and-brush” sequence only once or
twice in the apical third of the root canal.
Apical gauging is done according to the
previously mentioned protocol using a size
30/02, 40/02, or 50/02 NiTi instruments.
The 30/02 instrument was ﬁtting
snugly at working length in the palatal
root canal in the present case report.
The canals were obturated with ProTaper
Next X2 gutta-percha points in the
mesiobuccal and distobuccal root canals
and a ProTaper Next X3 gutta-percha point
(Dentsply/Maillefer) in the palatal root canal
as master cones using the Calamus
®
Dual
Obturation Unit (Dentsply/Maillefer). Figure
23 demonstrates the ﬁnal result after canal
obturation.
Preparation sequence for very
long and curved root canals

In selected clinical cases, the clinician
might ﬁnd that ProTaper Next X1 does not
progress to full working length even after
a few coronal circumferential brushing
motions. The authors then recommend
to create more coronal shape by using
ProTaper Next X1 followed by ProTaper
Next X2 up to two-thirds of the canal
length. This preparation sequence will
create enough lateral space in the coronal
two-thirds of the root canal to ensure that
ProTaper Next X1 can now be taken to full
working length without any difﬁculty.
Case report
The patient, a 50-year-old female, presents
with pain on her mandibular rigth ﬁrst molar
with a history of a previous emergency
root canal treatment. Clinical examination
revealed a broken down and leaking
temporary restoration possibly resulting in
coronal leakage. A periapical radiograph
revealed very long and curved mesial
roots. Also visible on the radiograph was
evidence of dentin triangles preventing
straight-line access into the mesial root
canals (Figure 24).
The defective temporary restoration
and caries were removed before the tooth
Figure 23: Final result after obturation
using the Calamus Dual Obturation Unit

(Dentsply/Maillefer)
Figure 24: Preoperative radiograph
of mandibular right ﬁrst molar. Note
the dentin triangle (arrow) preventing
straight-line access into the mesial root
canals
Figure 25: Access cavity preparation after the tooth
was restored with composite. Note the evidence
of the dentin triangles on the mesial aspect of the
canal oriﬁces
Figure 26: Length determination
radiograph showing straight-line access
of the K-ﬁles into all the root canal
systems
Figure 27A: ProTaper
Next X1 (with outstroke
brushing motion) is used
to secure the coronal two-
thirds of the canal length
Figure 27B: After irrigation,
recapitulation and re-
irrigation sequence with
sodium hypochlorite the
ProTaper Next X2 is then
used in the same manner
to secure the canal to the
same length
Figure 27C: ProTaper Next
X1 is then used until the
ﬁle can progress to full

working length
Figure 27D: After irrigation,
recapitulation and re-
irrigation, ProTaper Next
X2 is thereafter taken to
full working length
CLINICAL
Volume 7 Number 1 Endodontic
practice
19
was restored with composite and a new
access cavity prepared. Note the evidence
of dentin triangles on the mesial aspect
of the canal oriﬁces (Figure 25, arrows).
The dentin triangles were removed with a
ProTaper SX instrument, ensuring straight-
line access into all the root canals. Figure
26 shows the radiographic view of the
length determination conﬁrming straight-
line access into the root canals.
As mentioned before, the clinical
protocol for cases with very long and
curved root canals would be to allow
ProTaper Next X1 to progress to about
two-thirds of the canal length (Figure
27A). This is followed by irrigation,
recapitulation, and re-irrigation sequence
with sodium hypochlorite. ProTaper Next
X2 is then used in the same manner (with
circumferential outstroke brushing motions)

to the same length (Figure 27B). ProTaper
Next X1 is then used again to progress
with canal preparation to full working length
(Figure 27C) using the “touch-and-brush”
sequence as described before. ProTaper
Next X2 is then taken to full working length
(using the same protocol as described
before) (Figure 27D) after irrigation,
recapitulation, and re-irrigation of the root
canal.
Canals were gauged according to
the technique described before, and ﬁnal
preparation was done up to ProTaper Next
X2 in the mesial root canals and up to
ProTaper Next X3 in the distal root canal.
GuttaCore™ veriﬁers were ﬁtted (Figure
28A) to working length to conﬁrm the size
of obturators for each canal before the
canals were obturated with corresponding
GuttaCore obturators. Figure 28B shows
the postoperative result after obturation.
Shaping recommendations for
large diameter root canals or
retreatment of root canals
If the ﬁrst ﬁle to working length is a size 20
K-ﬁle and it is loose up to working length,
the shaping procedure can be initiated by
using ProTaper Next X2 (25/06). If the ﬁrst
ﬁles to length are a size 25/30, 30/35, or
40/45, and they are found to be loose in

the canal up to working length, the shaping
procedure can be initiated with ProTaper
Next X3 (30/07), X4 (40/06), and X5 (50/06)
respectively.
Case report
The patient, a 44-year-old female,
presented with pain and discomfort on her
maxillary right-central incisor. Radiographic
examination revealed that the tooth
was poorly root treated, and there was
evidence of a large periapical area (Figure
29A). After removal of the previous gutta
percha, it was possible to take a size 35
K-ﬁle to working length (Figure 29B).
Root canal preparation was initiated
by preparing the root canal to working
length with the ProTaper Next X4 (40/06)
instrument (Figure 30A). Apical gauging
with a 40/02 NiTi hand ﬁle revealed that
the tip of the ﬁle was loose at length and
able to travel past the predetermined
working length (Figure 30B) and that a size
Figure 30A: ProTaper Next X4
instrument taken to full working
length
Figure 30B: Apical gauging with
a 40/02 NiTi hand ﬁle revealed
that the tip of the ﬁle was loose
at length and able to travel past
the predetermined working

length
Figure 30C: Apical gauging with
a size 50/02 NiTi hand ﬁle was
unable to reach full working
length, penetrating to about 2
mm short of working length
Figure 29A: Preoperative
radiograph of the maxillary
right central incisor revealed
a previously underﬁlled root
canal treatment, and there was
evidence of a large periapical
area
Figure 29B: Length
determination, using a size 35
K-ﬁle
Figure 28A: GuttaCore
veriﬁers are ﬁtted to working
length to conﬁrm the size
of obturators that will be
used for obturation after the
canals were prepared with
ProTaper Next
Figure 28B: Postoperative result
after the canals were obturated
with GuttaCore obturators
20 Endodontic
practice
Volume 7 Number 1
CLINICAL

Figure 31A: After irrigation,
recapitulation, and re-irrigation,
a ProTaper Next X5 was taken to
full working length
Figure 31B: Apical gauging with
a size 50/02 nickel-titanium
hand ﬁle. The ﬁle was snug at
working length
Figure 31C: Postoperative result after the
root canal obturation
50/02 NiTi hand ﬁle was unable to reach
full working length, penetrating to about 2
mm short of working length (Figure 30C).
This indicated that the apical foramen size
was between 0.40 mm and 0.50 mm. The
root canal preparation was enlarged with
a ProTaper Next X5 (50/06) (Figure 31A)
and gauged again with a 50/02 hand NiTi
ﬁle (Figure 5F). It was found that the 50/02
REFERENCES
Arens FC, Hoen MM, Steiman HR, Dietz GC Jr.
Evaluation of single-use rotary nickel-titanium
instruments. J Endod. 2003;29(6):664-666.
Berutti E, Cantatore G, Castellucci A, Chiandussi G,
Pera F, Migliaretti G, Pasqualini D. Use of nickel-
titanium rotary PathFile to create the glide path:
comparison with manual preﬂaring in simulated root
canals. J Endod. 2009;35(3):408-412.
Berutti E, Chiandussi G, Gaviglio I, Abba A.
Comparative analyses of torsional and bending

stresses in two mathematical models of nickel-titanium
rotary instruments: ProTaper vesus Proﬁle. J Endod.
2003;29(1):15-19.
Berutti E, Negro AR, Lendini M, Pasqualini D. Inﬂuence
of manual preﬂaring and torque on the failure rate of
ProTaper rotary instruments. J Endod. 2004;30(4):228-
230.
Bird DC, Chambers D, Peters OA. Usage parameters
of nickel-titanium rotary instruments: a survey
of endodontics in the United States. J Endod.
2009;35(9):1193-1197.
Blum JY, Cohen A, Machtou P, Micallef JP. Analysis
of forces developed during mechanical preparation of
extracted teeth using Proﬁle NiTi rotary instruments. Int
Endod J. 1999;32(1):24-31.
Chen JL, Messer HH. A comparison of stainless
steel hand and rotary nickel-titanium instrumentation
using a silicone impression technique. Aust Dent J.
2002;47(1):12-20.
Glossen CR, Haller RH, Dove SB, del Rio CE. A
comparison of root canal preparations using Ni-Ti
hand, Ni-Ti engine-driven, and K-Flex endodontic
instruments. J Endod. 1995;21(3):146-151.
Gutmann JL, Gao Y. Alteration in the inherent metallic
and surface properties of nickel-titanium root canal
instruments to enhance performance, durability and
safety: a focused review. Int Endod J. 2012;45(2):113-
128.
Johnson E, Lloyd A, Kuttler S, Namerow K. Comparison
between a novel nickel-titanium alloy and 508 nitinol

on the cyclic fatigue life of ProFile 25/.04 rotary
instruments. J Endod. 2008;34(11):1406-1409.
Kim HC, Kwak SW, Cheung GS, Ko DH, Chung SM,
Lee W. Cyclic fatigue and torsional resistance of two
new nickel-titanium instruments used in reciprocation
motion: Reciproc versus WaveOne. J Endod.
2012;38(4):541-544.
Parashos P, Messer HH. Rotary NiTi instrument fracture
and its consequences. J Endod. 2006;32(11):1031-
1043.
Peters OA. Current challenges and concepts in the
preparation of root canal systems: a review. J Endod.
2004;30(8):559-567.
Ruddle CJ. The ProTaper endodontic system:
geometries, features, and guidelines for use. Dent
Today. 2001;20(10):60-67.
Ruddle CJ, Machtou P, West JD. The shaping
movement: ﬁfth-generation technology. Dent Today.
2013;32(4):94, 96-99.
Sattapan B, Nervo GJ, Palamara JF, Messer HH.
Defects in rotary nickel-titanium ﬁles after clinical use. J
Endod. 2000;26(3):161-165.
Scianamblo MJ, inventor. Endodontic instruments
for preparing endodontic cavity spaces. US patent
6942484, 7094056, 7955078 and 20060228669. May
20, 2011.
Short JA, Morgan LA, Baumgartner JC. A comparison
of canal centering ability of four instrumentation
techniques. J Endod. 1997;23(8):503-507.
Van der Vyver PJ. Creating a glide path for rotary

NiTi instruments: Part one. Endodontic Practice.
2011;14(1)40-43.
Patiño PV, Biedma BM, Liébana CR, Cantatore G,
Bahillo J. The inﬂuence of a manual glide path on the
separation rate of NiTi rotary instruments. J Endod.
2005;31(2):114-116.
Walia HM, Brantley WA, Gerstein H. An initial
investigation of the bending and torsional properties of
Nitinol root canal ﬁles. J Endod. 1988;14(7):346-351.
West JD. Introduction of a new rotary endodontic
system: progressively tapering ﬁles. Dent Today.
2001;20(5):50-52, 54-57.
West J. Endodontic update 2006. J Esthet Restor Dent.
2006;18(5):280-300.
West JD. The endodontic Glidepath: “Secret to rotary
safety”. Dent Today. 2010;29(9):86, 88, 90-93.
Yun HH, Kim SK. A comparison of the shaping abilities
of 4 nickel-titanium rotary instruments in simulated
root canals. Oral Surg Oral Med Oral Pathol Oral Radiol
Endod. 2003;95(2):228-233.
instrument ﬁtted snug at working length
(Figure 31B) indicated that the shape
was complete. The prepared canal was
obturated with a ProTaper Next X5 gutta-
percha point (Dentsply/Maillefer) using
Calamus Dual Obturation Unit (Dentsply/
Maillefer). Figure 31C shows the ﬁnal result
after obturation.
Part 2 of this series will discuss the
management of complex root canal

systems with the ProTaper Next system
(Dentsply/Maillefer).
EP

OPERATORY COMPUTER
MICROSCOPE
ONLINE PORTAL
IMAGING EQUIPMENT
MAKE IT POSSIBLE
WITH TDO SOFTWARE
We’re that something you’ve been searching for. Ask yourself:

WHAT IF I could surround myself with employees committed to clinical and practice excellence?

WHAT IF my support team was exceptional because of complete commitment to my vision?

WHAT IF I had immediate, meaningful, and quality contact with my
referrals every minute of every day?

WHAT IF I had hundreds of world-class endodontists
mentoring me daily, helping me to become more successful?

WHAT IF my patients recognized immediately that my
practice was centered around quality?
TDO_Endo_Pract_Mag_9.5X12.2.indd 2 12/5/13 12:27 AM
I
ntracanal microbes are the cause of
endodontic disease.
1-3
The prevention or

removal of microbes from the root canal
system during treatment is the factor
that determines if the treatment will be
successful or not.
4-5
Root canal instrumentation is one of
the major tools to ensure the long-term
success of root canal therapy.
6-7
The aim
is to mechanically disrupt as much bioﬁlm
as possible so that with the addition of
irrigants and/or intra-canal medicaments, a
very low microbial count can consistently
be achieved before root canal ﬁlling.
Another aim/challenge of root canal
instrumentation is to achieve the microbial
reduction goals previously mentioned
without unnecessarily weakening the root
by over-instrumentation, i.e., reduction
of the dentin wall thickness. Preservation
of native tooth structure, especially in the
cervical region of the tooth, has been
demonstrated to correspond to better
long-term survivability from a loading and
restorative standpoint. It is well established
that as the remaining dentin thickness
decreases, so the root decreases in its
resistance to fracture.
8

What is the ideal root canal
instrumentation size?
The axiom: The ﬁle alone does not remove
the maximum amount of bioﬁlm but works
with irrigation in a synergistic effect with the
ﬁle. The key question is, What is the ideal
instrumentation size to achieve the desired
goal of bioﬁlm elimination? In order to
answer this question, we need to analyze
anatomical studies and evaluate whether
and how it is possible to remove bioﬁlm
from these canals.
When evaluating the anatomical
studies, it is interesting to note how
consistent they are! (Figure 1) best
summarizes the anatomical aims for a
mandibular molar.
First, let’s look at the mesio-buccal
and mesio-lingual canals at the 1 mm
measurement from the apical foramen,
which corresponds most closely to the
dentino-cemental junction. In the mesial-
distal direction, the diameters are 0.21 and
0.28, respectively. Thus, ﬁnishing at a No.
25 ﬁle would appear to be sufﬁcient when
viewed with a periapical radiograph since
the mesio-distal direction is what we see
on the radiograph. However, if we look
at the bucco-lingual direction, the correct
sizes are between No. 35 and No. 40!

For the distal canal, a No. 35 would look
adequate on the radiograph (mesio-distal
view), but the correct size would be No. 50.
Thus, we might take a popular
saying from our colleagues who advocate
thermoplastic obturation: “If we want to
clean in three dimensions, we need to
instrument in the bucco/lingual dimension
also.” Just as important, if we look at the
measurements at 2 mm and 5 mm from
the end of the root, it is apparent that if we
in fact do instrument to the apical sizes
required (No. 35 or No. 40 mesial and
No. 50 distal), then a 0.04 taper is all that
is needed to contact the walls in these
areas farther from the apex. Using tapers
larger than 0.04 is not required to remove
microbes and unnecessarily weakens the
root. Anatomical studies of all roots follow
this basic biological rule; i.e., No. 35 or No.
40 for the “smaller” canals and No. 50 for
the “larger” canals.
9-11
BT-Race — Biologic and conservative root canal
instrumentation with the ﬁnal restoration in mind
22 Endodontic
practice
Volume 7 Number 1
CLINICAL
Drs. Gilberto Debelian and Martin Trope explore the BT-Race system

Figure 1
Gilberto Debelian, DMD, PhD, received his DMD degree from the University of Sao Paulo, Brazil, in 1987. He
completed his specialization in Endodontics from the University of Pennsylvania, School of Dental Medicine, in
1991.He has taught as a clinical instructor and associate professor at the post-doctoral endodontic program
at the Department of Endodontics, University of Oslo, Norway, from 1991 to 2001, and from 2006 to 2010.
He concluded his PhD studies at the University of Oslo, Norway, in 1997 on endodontic microbiology. He
is an adjunct visiting professor at the post-graduate program in endodontics, University of North Carolina in
Chapel Hill, and University of Pennsylvania in Philadelphia. Dr. Debelian maintains a private practice limited to
endodontics as well as an advanced endodontic microscopy center, EndoInn, in Bekkestua, Norway. He is an
author of books and 50 scientiﬁc and clinical papers and is currently a member of the scientiﬁc advisory panel
for the Journal of Endodontics and Endodontic Practice Today, director of the Oslo Endodontic Study Club, and
the vice-president of the Norwegian Endodontic Society.
Martin Trope, BDS, was born in Johannesburg, South Africa, where he received his BDS degree in dentistry in
1976. From 1976 to 1980, he practiced general dentistry and endodontics. In 1980, he moved to Philadelphia
to specialize in endodontics at the University of Pennsylvania. After graduating as an endodontist, he continued
at the University of Pennsylvania as a faculty member until 1989 when he became Chair of Endodontology at
Temple University, School of Dentistry. In 1993, he accepted the JB Freedland Professorship in the Department
of Endodontics at the University of North Carolina at Chapel Hill, School of Dentistry. Dr. Trope is now Clinical
Professor, Department of Endodontics, School of Dental Medicine, University of Pennsylvania. He is also in
private practice in Philadelphia, PA. He has served as a Director of the American Board of Endodontics. Before
entering full-time private practice, he was editor-in-chief of two journals, Dental Traumatology and Endodontic
Topics. He also serves on the Editorial Board of Oral Surgery, Oral Medicine, Oral Pathology and on the
Advisory Board of Esthetic Dentistry. His work has been published in numerous journals and book chapters. In
April 2002, he was awarded The Louis I. Grossman Award for cumulative publication of signiﬁcant research by
the American Association of Endodontists.
Both authors maintain full-time private endodontic specialty practices while serving as consultants to various
manufactures, including the manufacturer of the BT Race ﬁle system.
CLINICAL
Volume 7 Number 1 Endodontic
practice

23
Ideal shape for an instrumented
canal?
Adequate biological sizes with minimal
taper with the least number of ﬁles
Thus, in order to achieve the aims stated
above, i.e., maximal bioﬁlm disruption with
minimal weakening of the root, we should
aim for No. 35, No. 40, or No. 50 apical
sizes with no more that 0.04 taper.
9-11
These biological sizes with the addition of
an adequate irrigation protocol will ensure a
consistently low microbial count to ensure
maximal success.
BT-Race system — biologic and
conservative
BT-Race ﬁles (Brasseler USA) are sterilized
in individual blisters so that sterility is
ensured for every ﬁle. (Figure 2)
The biologic sizes mentioned
previously can be achieved in three ﬁles
every time after a glide path is achieved.
The system is designed so that these
sizes are attained with minimal removal
of unnecessary dentin coronally so as to
maintain the strength of the root.
The BT-Race ﬁle has a non-screw-in
design, triangular cross section to increase
ﬂexibility and cutting efﬁciency and is

electro-polished to decrease the effects of
torsional and cyclic fatigue. (Figure 3)
Booster Tip (BT)
The booster tip is the key feature of these
ﬁles that allows them to follow curvatures
in canals without undue stress on the ﬁle
or the root. The Booster Tip ﬁles start as
a non-cutting tip from 0 mm to 0.17 mm
diameter, and the cutting edges start from
0.17 mm and upward on the ﬁle. This allows
these ﬁles to safely follow a canal even
with a very narrow diameter. The ﬁnal size
of the ﬁle is achieved within 0.5 mm of the
tip. Thus, for example, the BT2 (see Figure
4), which is a non-tapered ﬁle with a cutting
size of 0.35 mm, can still easily advance
into the canal prepared by the glide path
ﬁle, which is 0.15mm in diameter.
The booster tip allows a ﬁle of any
diameter to follow the shape of a canal that
has been prepared with a No. 15 glide path
stainless-steel ﬁle. However, the protocol
of three ﬁles (see Figure 5) is designed to
relieve undue stress on the root and ﬁles
while instrumenting the canal to biologically
accepted sizes.
Essentials for successful use of
the BT-Race sequence
1. Glide path.
In order to guarantee a minimal number of

ﬁle breakages, a glide path to No. 15/0.02
taper is essential. Hand ﬁles can usually
achieve this aim. However if a No. 6 or No.
10 is extremely difﬁcult to get to working
length, then ScoutRace ﬁles (Brasseler
USA) allow endodontists to achieve this
requirement more quickly.
2. Speed of 800–1000 RPM
A high speed reduces the risk of breakage
due to torsional fatigue, and since these
ﬁles are for single-patient use only, the
chances of breakage from cyclic fatigue is
also reduced. Thus, by using high speed
and limiting the number of usages to one,
we are limiting the chances of breakage of
these ﬁles.
BT1 – 10/0.06
This ﬁle establishes the ﬁnal glide path and
determines the coronal diameter. In any
canal in which a No. 15/0.02 glide path has
been achieved, the ﬁle will contact mainly
the coronal third of the canal. At 12 mm
Figure 2 Figure 3 Figure 4
Figure 5
Figure 6: BT1 - 10/0.06, BT2 - 35/0.00, and BT3 -
35/0.04
Figure 7: BT-Race XL - BT40/0.04 and BT 50/0.04 (600-
800 RPM). These two instruments enable ﬁnishes at ISO
No. 40 and No. 50 when adequate apical sizes require
larger sizes. If even larger apical preparations than ISO

No. 50 are required, use the Race range of instruments to
the required sizes, preferable with small taper 0.02.

Tạp chí nội nha OPUS tháng 01+02/2014 Vol.7 No.1

Tài liệu liên quan

Tài liệu bạn tìm kiếm đã sẵn sàng tải về