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

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

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A conservative

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Drs David Keinan and

Feedback – lateral thinking

Jacqui Goss

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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

Garry Nervo BDSc, LDS, MDSc, FRACDS, FICD, FPFA

Wilhelm Pertot DCSD, DEA, PhD

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: lmoler@medmarkaz.com Tel: (480) 403-1505

MANAGING EDITOR | Mali Schantz-Feld

Email: mali@medmarkaz.com Tel: (727) 515-5118

ASSISTANT EDITOR | Elizabeth Romanek

Email: betty@medmarkaz.com Tel: (727) 560-0255

EDITORIAL ASSISTANT | Mandi Gross

Email: mandi@medmarkaz.com Tel: (727) 393-3394

DIRECTOR OF SALES | Michelle Manning

Email: michelle@medmarkaz.com Tel: (480) 621-8955

NATIONAL SALES/MARKETING MANAGER

Drew Thornley

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PRODUCTION MANAGER/CLIENT RELATIONS

Adrienne Good

Email: agood@medmarkaz.com Tel: (623) 340-4373

PRODUCTION ASST./SUBSCRIPTION COORD

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.

The 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 factors2 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 start3 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, DMDDiplomate, American Board of EndodonticsClinical Associate Professor of Endodontics, University of Pennsylvaniawww.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.

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

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

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

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 fibers 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 2002;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 fibers

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

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

Clinical management

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, 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,

frac-my treatment process is a lot less stressful My patients benefit from the technology and frac-my

referrals appreciate the value.” ~ Dr Kathryn Stuart, Endodontist - Fishers, Indiana

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

“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.

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

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 paradigmSonendo’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 cially available for sale or distribution

commer-For more information, visitwww.sonendo.com

This information was provided by Sonendo.

EP

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 instrumentation or under-instrumentation — can occur because of inaccurate estimates

over-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.

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

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

ResultsThe 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)

DiscussionThis 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

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

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

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

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

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

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

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

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

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

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 line access and remove triangles

straight-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)

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

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

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

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 thirds of the canal length

two-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

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 reportThe 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

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

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Berutti E, Cantatore G, Castellucci A, Chiandussi G,

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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

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

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

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

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practice was centered around quality?

Iendodontic 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

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

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.

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

1 Kakehashi S, Stanley HR, Fitzgerald RJ The effects

of surgical exposures of dental pulps in germ-free and

conventional laboratory rats Oral Surg Oral Med Oral

Pathol 1965;20:340-349.

2 Bergenholtz G Micro-organisms from necrotic pulp

of traumatized teeth Odontol Revy

1974;25(4):347-358.

3 Möller AJ, Fabricius L, Dahlén G, Ohman AE, Heyden

G Influence on periapical tissues of indigenous oral

bacteria and necrotic pulp tissue in monkeys Scand J

Dent Res 1981;89(6):475-484.

4 Sjögren U, Figdor D, Persson S, Sundqvist G

Influence of infection at the time of root filling on the

outcome of endodontic treatment of teeth with apical

periodontitis Int Endod J 1997;30(5):297-306

5 Waltimo T, Trope M, Haapasalo M, Ørstavik D

Clinical efficacy of treatment procedures in endodontic infection control and one year follow-up of periapical

healing J Endod 2005;31(12):863-866

6 Dalton BC, Orstavik D, Phillips C, Pettiette M, Trope

M Bacterial reduction with nickel titanium rotary

instrumentation J Endod 1998;24(11):763-767.

7 Shuping GB, Orstavik D, Sigurdsson A, Trope M

Reduction of intracanal bacteria using nickel-titanium

rotary instrumentation and various medications J

Endod 2000;26(12):751-755

8 Trope M, Maltz DO, Tronstad L Resistance to

fracture of restored endodontically treated teeth

Endod Dent Traumatol 1985;1(3):108-111.

9 Vertucci FJ Root canal morphology and its

relationship to endodontic procedures Endod Topics

2005;89(6):3-29.

10 Wu MK, R’oris A, Barkis D, Wesselink PR

Prevalence and extent of long oval canals in the apical

third Oral Surg Oral Med Oral Pathol Oral Radiol

Endod 2000;89(6):739-743.

11 Villas-Bôas MH, Bernardineli N, Cavenago BC, Marciano M, Del Carpio-Perochena A, de Moraes IG, Duarte MH, Bramante CM, Ordinola-Zapata R Micro- computed tomography study of the internal anatomy

of mesial roots of mandibular molars J Endod

2011;37(12):1682-1686.

from the working length, the diameter will

be 0.82 mm These files have no booster tip

since the tip diameter is already 0.10 mm

and smaller than the glide path established

with a K-File No 15/0.02

BT2 – parallel no 35 file with Booster

Tip

The BT2 file is used to prepare the apical

third of the canal The file is extremely

flexible due to its non-tapered design and

yet easily and efficiently penetrates into the

narrow canal due to the BT Tip

BT3 - no 35/0.04 with Booster Tip

This file is used to join the coronal and

apical preparations created by the BT1 and

Figure 10 Figure 11

BT2 and thus create a No 35/0.04 final shape that allows maximal irrigation and a tight-fitting cone fit The file is able to get

to working length with minimal stress since the coronal has been cleared by BT1 and the apical cleared with BT2 file

Importantly, in this canal the maximum diameter at the 12 mm level is 0.83 mm

Thus, the removal of coronal dentin is minimal allowing for the strongest root possible after restoration

ConclusionWith this unique file system, all canals can be conservatively instrumented to the correct biological sizes while maintaining maximum cervical tooth structure that

remains following instrumentation The booster tip ensures that the original canal shape is maintained, thus, keeping even the larger files centered in the canal With this centering advantage, in addition to the minimal taper required to achieve these biologic sizes, the canal is maximally cleaned without weakening or stressing the root

case studies note that these cases fulfill the objective of biologic apical sizes with conservative coronal removal

of dentin Thus, they have a high probability of endodontic success and survivability EP

Volume 7 Number 1 Endodontic practice 25

Abstract

This article presents a case demonstrating

a new and conservative approach for

bleaching anterior teeth with

yellowish-brown discoloration secondary to pulp

chamber calcification There was also

no response to cold stimulation, and the

periodontal ligament was radiographically

continuous and normal in width The

patient preferred to avoid the option of

external bleaching or tooth preparation for

laminate veneer The presented technique

offers a comparatively conservative

approach in the treatment of anterior

tooth discoloration associated with pulp

chamber obliteration The esthetic results

are consistent with non-vital tooth internal

bleaching; yet pre-bleaching root canal

treatment is not requested

Introduction

Internal bleaching is a well-known

commonly used clinical procedure for the

treatment of discoloration of endodontically

treated anterior teeth (Rotstein, Zalkind, et

al., 1991; Amato, Scaravilli, et al., 2006)

However, it is not uncommon to have a

discolored vital anterior tooth due to pulp

chamber calcification (Abbott and Heah,

2009) This pulp chamber calcification is

caused by excessive dentin apposition by

the odontoblasts that may be accelerated

because of trauma to the tooth (Abbott

and Heah, 2009) Consequently, there is a

decrease in the translucency of the tooth

resulting in a yellowing to dark discoloration

(Abbott, 1997)

There are several approaches to deal

with this esthetic problem The common

and often most predictable technique

involves tooth preparation for a laminate

veneer or full porcelain crown (Chen and Raigrodski, 2008; Jun and Wilson, 2008;

Sadighpour, Geramipanah, et al., 2009;

Freire and Archegas 2010; Alghazzawi, Lemons, et al., 2012; Beier, Kapferer, et al., 2012) However, these options result

in irreversible removal of tooth structure and may present barriers in expense and esthetics

Using external vital tooth bleaching procedure for color change secondary to a calcified pulp chamber has limited efficacy

External bleaching techniques involve the use of a customized mouth tray with carbamide peroxide gels as the bleaching medium (Fasanaro 1992; Haywood 1992;

Haywood 1992; Kielbassa, Attin, et al., 1995; Attin, Paque, et al., 2003) External bleaching of a single tooth is carried out

by using 20% carbamide peroxide gel for

a period of 4 to 6 weeks or until the single tooth matches all the adjacent teeth The technique requires modifying the bleaching tray in order to make space for the bleaching agent and limit its action to the discolored tooth

The high success rate and simplicity

of non-vital tooth bleaching technique requires endodontic treatment prior to

initiating internal bleaching (Rotstein, Zalkind, et al., 1991; Amato, Scaravilli, et al., 2006) This approach is also used to reduce tetracycline and other sources of discoloration (Abou-Rass 1982) However, this method for bleaching of a tooth with

a calcified pulp chamber has two main disadvantages First, the endodontic treatment can be a costly procedure as well as being irreversible Second, since there is calcific metamorphosis, there is

a risk for crown or root perforation while trying to find or negotiate the calcified canal space

The presented case report offers

a conservative approach for treating discoloration due to pulp chamber obliteration This approach may reduce the amount of unnecessary laminate veneers

or root canal treatments performed before internal bleaching in refractory cases to external bleaching

Case report

A 35-year-old man complained about discoloration of his maxillary left central incisor (Figure 1A) The patient did not report pain or sensitivity to temperature changes

or percussion Radiographic examination

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

Figures 1A and 1B: Pre-treatment radiograph (1A) of the maxillary left central incisor with an obliterated pulp chamber, and 1-year recall radiograph (1B) following conservative coronal bleaching treatment

David Keinan, DMD, PhD, is in the Department of

Endodontics, Medical Corps, Tel Hashomer Hospital,

Ramat-Gan, Israel.

Eugene A Pantera Jr., DDS, MS, is in the Department

of Periodontics and Endodontics, School of Dental

Medicine, University at Buffalo, the State University of

New York, Buffalo, New York.

revealed complete calcification of the pulp

chamber and the root canal space The

periodontal ligament was continuous with

no widening, and the lamina dura appeared

normal (Figure 2A)

At the first visit, the tooth was

isolated by using a rubber dam (Hygenic®,

Coltène®/Whaledent) and an access cavity

was designed similar to a normal pulp

chamber to the level of the

cemental-enamel junction This step was performed

without anesthesia in order to get feedback

from the patient for the possibility of neural

fibers within a microscopic canal A resin

modified glass ionomer (RMGI) liner (3M™

ESPE™ Vitrebond™ Light Cure Glass

Ionomer Liner/Base, VB) was lined over

the calcified canal orifice A mixture of

sodium perborate (SP) was inserted as the

common protocol for internal bleaching A

week later, on the second visit, there was

major color change, and the bleaching

process was repeated again In the final

visit, the color change satisfied the patient

(Figure 2B), the SP was flushed out,

and a temporary restoration with a zinc

oxide-calcium sulfate premixed material

(Coltosol®, Colten, Langenau, Germany)

was placed The patient was referred to

his dentist for placement of a permanent

restoration The patient presented after

1 year to a follow-up examination with

no symptoms, and the recall radiograph

revealed a continuous PDL (Figure 1B) The

last follow-up examination, 3 years after

treatment, also revealed no symptoms,

color satisfaction (Figure 3A), and the same

conical root with continuous PDL (Figure

3B)

DiscussionThe presented technique recommends a relatively conservative approach in cases with vital tooth discoloration due to pulp chamber obliteration that did not respond

to external bleaching Clinically, as in the presented cases, it is not uncommon to see some color improvement after the first step of making an access cavity This may be attributed to improving some of the tooth transparency that was reduced

by the dentin apposition (Abbott, 1997)

We recommend offering the patient trying external bleaching first since it does not involve any tooth preparation The patient should also be informed about the limited possibility to predict the effect of external bleaching in those cases

The presented bleaching option should be carefully selected for asymp-tomatic cases with pulp chamber calcifica-tion When using the technique previously described, the patient should be informed about the risk of irritating the remaining pulp tissue in the canal, yet it is minimal for several reasons First, H2O2 is synthe-sized by the human body itself as a mean

of defense (McKenna and Davies, 1988);

second, the GIC lining on the access ity floor prevents H2O2 penetrating the canal Furthermore, even during external bleaching, a small amount of H2O2 pen-etrates into the pulp chamber (Bowles and Ugwuneri, 1987) Third, when the favorable prognosis of external vital tooth bleaching

cav-is weighed against minimal rcav-isk of irritating the pulp, it can be assumed that even if small amount of H2O2 penetrates the GIC barrier, it would have minimal influence;

and finally, if there are signs of pulpal

dis-tubules (Kawamoto and Tsujimoto, 2004)

It oxidizes and bleaches the iron sulfide and other pigments present in the dentinal tubules (Attin, Paque, et al., 2003) Free radicals can cause oxidative effects to lipids, proteins, and nucleic acids (Floyd 1997; Park and Floyd, 1997; Kwon, Lee, et al., 1998) Although free radicals are suspected of being mutagenic and carcinogenic (Attin, Paque, et al., 2003), this risk is mitigated with appropriate use

of H2O2 during (Rotstein, Zyskind, et al., 1992; Steiner and West, 1994) and after (Li, Sole, et al., 1998) bleaching therapy Yet, since sensitivity increases with age, high concentrations of H2O2 or extended contact of H2O2 with tissues (Floyd and Carney, 1992; Smith, Carney, et al., 1992; Stadtman, Starke-Reed, et al., 1992; Li, Yan, et al., 1998) should be avoided Care should be taken to minimize the number

of times SP is refreshed as well in order

to decrease risk of coronal fracture (Tam, Kuo, et al., 2007; Azevedo, Silva-Sousa, et al., 2011)

The recommended clinical steps for our modified technique include:

1 Access cavity preparation in the pulp chamber without entering the canal

2 Sealing the floor of the access cavity with glass ionomer cement

3 Applying sodium perborate mixed with saline

4 Placing an intermediate restoration for 4-7 days

This procedure may be repeated several times (2-5), while laminate veneers should be considered for refractory cases Additionally, this treatment may be followed

by external bleaching with carbamide peroxide, especially in cases of persistent discoloration due to external layer stain (West, 1997)

Included in any informed consent regarding bleaching procedures is the need to inform the patient of possibility

of requiring endodontic treatment if symptoms of pulpal disease develop

Figures 2A and 2B: Pre- (2A) and post- (2B) coronal bleaching photographs of

the maxillary left central incisor

Figures 3A and 3B: Three-year follow-up photo (3A) and radiograph (3B) showing clinically and radiographically satisfying results

EP

Volume 7 Number 1 Endodontic practice 27

REfEREncEs

Abbott P, Heah SY Internal bleaching of teeth: an

analysis of 255 teeth Aust Dent J 2009;54(4)326-333.

Abbott PV Aesthetic considerations in endodontics:

internal bleaching Pract Periodontics Aesthet Dent

1997;9(7):833-840, 842.

Abou-Rass M The elimination of tetracycline

discoloration by intentional endodontics and internal

bleaching J Endod 1982;8(3):101-106.

Alghazzawi TF, Lemons J, Liu PR, Essig ME, Janowski

GM Evaluation of the optical properties of CAD-CAM

laminate veneers J Prosthet Dent

2012;107(5)300-308.

Amato M, Scaravilli MS, Farella M, Riccitiello F

Bleaching teeth treated endodontically: long-term

evaluation of a case series J Endod

2006;32(4):376-378.

Attin T, Paqué F, Ajam F, Lennon AM Review of the

current status of tooth whitening with the walking

bleach technique Int Endod J 2003;36(5):313-329.

Azevedo RA, Silva-Sousa YT, Souza-Gabriel AE,

Messias DC, Alfredo E, Silva RG Fracture resistance

of teeth subjected to internal bleaching and restored

with different procedures Braz Dent J

2011;22(2):117-121.

Beier US, Kapferer I, Burtscher D, Dumfahrt H Clinical

performance of porcelain laminate veneers for up to 20

years Int J Prosthodont 2012;25(1):79-85.

Bowles WH, Ugwuneri Z Pulp chamber penetration

by hydrogen peroxide following vital bleaching

procedures J Endod 1987;13(8):375-377.

Chen YW, Raigrodski AJ A conservative approach for

treating young adult patients with porcelain laminate

veneers J Esthet Restor Dent 2008;20(4):223-236,

237-228.

Fasanaro TS Bleaching teeth: history, chemicals, and

methods used for common tooth discolorations J

orders@engineeredendo.com www.engineeredendo.com

The Finishing File is the most cost effective

and simplest way to clean a canal!

THE FUTURE HAS RETURNED.

Floyd RA The effect of peroxides and free radicals on

body tissues J Am Dent Assoc

1997;128(suppl):37S-40S.

Floyd RA, Carney JM Free radical damage to protein and DNA: mechanisms involved and relevant observations on brain undergoing oxidative stress

Ann Neurol 1992;32(suppl):S22-27.

Freire A, Archegas LR (2010) Porcelain laminate veneer

on a highly discoloured tooth: a case report J Can

Dent Assoc 2010;76:a126.

Haywood VB Bleaching of vital and nonvital teeth

Curr Opin Dent 1992;2:142-149.

Haywood VB History, safety, and effectiveness of current bleaching techniques and applications of the

nightguard vital bleaching technique Quintessence Int

Kawamoto K, Tsujimoto Y Effects of the hydroxyl

radical and hydrogen peroxide on tooth bleaching J

Endod 2004;30(1):45-50.

Kielbassa AM, Attin T, Schaller HG, Hellwig E

Endodontic therapy in a postirradiated child: review of

the literature and report of a case Quintessence Int

Li RK, Sole MJ, Mickle DA, Schimmer J, Goldstein

D Vitamin E and oxidative stress in the heart of the

cardiomyopathic syrian hamster Free Radic Biol Med

and RNA synthesis Basic Life Sci 1988;49:829-832.

Park JW, Floyd RA Glutathione/Fe3+/O2-mediated DNA strand breaks and 8-hydroxydeoxyguanosine formation Enhancement by copper, zinc superoxide

dismutase Biochim Biophys Acta

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Rotstein I, Zalkind M, Mor C, Tarabeah A, Friedman S

In vitro efficacy of sodium perborate preparations used for intracoronal bleaching of discolored non-vital teeth

Endod Dent Traumatol 1991;7(4):177-180.

Rotstein I, Zyskind D, Lewinstein I, Bamberger

N Effect of different protective base materials on hydrogen peroxide leakage during intracoronal

bleaching in vitro J Endod 1992;18(3):114-117.

Sadighpour L, Geramipanah F, Nikzad S Fixed rehabilitation of an ACP PDI class III patient

with amelogenesis imperfecta J Prosthodont

2009;18(1):64-70.

Smith CD, Carney JM, Tatsumo T, Stadtman ER, Floyd

RA, Markesbery WR Protein oxidation in aging brain

Ann N Y Acad Sci 1992;663:110-119.

Stadtman ER, Starke-Reed PE, Oliver CN, Carney

JM, Floyd RA Protein modification in aging EXS

1992;62:64-72.

Steiner DR, West JD A method to determine the

location and shape of an intracoronal bleach barrier J

West JD The aesthetic and endodontic dilemmas of

calcific metamorphosis Pract Periodontics Aesthet

Dent 1997;9(3):289-293, 294.

Tcleaning, shaping, and obturation

of the root canal system, which are the

foundations for predictable endodontic

success, were outlined by Schilder over

4 decades ago and remain pertinent even

with all the technological advances that

have been made since the turn of the 21st

century (Schilder, 1967; Schilder, 1974)

The preparation of the root canal system

remains one of the most difficult tasks in

endodontic treatment (Hülsmann, Peters,

Dummer, 2005) due to the complex

anatomy of root canals, with their irregular,

non-circular cross sections, multiplanar

curves, bifurcations, trifurcations, fins,

vagaries, and cul-de-sacs (Figures 1

and 2) They often present extreme

challenges to clinicians who aim to create a

conservative, predictable shape conducive

to three-dimensional obturation and a

sound restoration It does not take much

to lose control of the root canal space with

subsequent iatrogenic mishaps, such as

apical ledges or the packing of dentinal

debris; both of which may jeopardize apical

patency Additionally, canal transportation

can undesirably alter the diameter and

special position of the apical foramen,

as well as the working length, thereby

adversely affecting the apical seal (Wu,

Fan, Wesselink, 2000) and potentially

causing irritation to the periapical tissues

by extruded irrigants and irritants (Schäfer, Dammaschke, 2009)

Mounce (2004) outlined certain “sound principles” that must be adhered to before treatment These include a comprehensive appraisal of the tooth being treated, canal numbers, location, length, curvatures at all levels, the presence of calcifications, anomalous anatomy, access difficulties, and so on Superior illumination and magnification, an adequate well-designed access, good irrigation techniques, and re-capitulation are all essential ingredients

to gaining control over the canal being treated

Figure 1: Complex root canal anatomy

Yosef Nahmias, DDS, MSc, was born and raised in Mexico City After he had graduated from the Universidad

Tecnologica de Mexico, School of Dentistry, in 1980 with a degree in dentistry, he decided to advance his

education and chose endodontics as his specialty He earned his Master of Science degree in 1983

Dr Nahmias has authored and published many articles He lectures in Canada, Mexico, and across South

America Dr Nahmias resides in Toronto, Ontario, and has maintained a private practice specializing in

endodontics in Oakville, Ontario, since 1983

Imran Cassim, BDS, WITS, PG Dip Dent Endo (Cum Laude), qualified with a BDS degree from University Of

Witwatersrand in South Africa in 1999 He attained distinctions in physiology, pharmacology, and anesthetics

during his undergraduate study In 2009, he completed his postgraduate diploma in endodontics at University

of Pretoria in South Africa, with distinctions in oral biology and endodontics Dr Cassim is currently studying

part-time toward an MSc in Endodontics at University of Pretoria, and in private practice focusing mainly on

endodontics and restorative dentistry in Durban, South Africa.

Gary Glassman, DDS, FRCD(C), graduated from the University of Toronto, Faculty of Dentistry in 1984 and

was awarded the James B Willmott Scholarship, the Mosby Scholarship, and the George Hare Endodontic

Scholarship for proficiency in Endodontics A graduate of the endodontology program at Temple University in

1987, he received the Louis I Grossman Study Club Award for academic and clinical proficiency in Endodontics

Dr Glassman lectures globally on endodontics and has authored numerous publications He maintains a private

practice, Endodontic Specialists in Toronto, Ontario, Canada

Educational aims and objectives

This clinical article aims to explain how a reproducible glide path can reduce iatrogenic mishaps and achieve more successful outcomes.

Expected outcomes

Correctly answering the questions on page 33, worth 2 hours of CE, will demonstrate you can:

• Identify “glide path” as explained by various clinicians.

• Realize that the incorporation of modern mechanized files into the instrumentation protocol will help achieve a reproducible glide path.

Figure 2: Maxillary first molar anatomy