Endo Tribune U.S.
3-D imaging and endodontics: educated guess becomes scientific decision / Apical microsurgery: the REB and REP
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[1] =>
ENDO TRIBUNE
The World’s Endodontic Newspaper · U.S. Edition
August 2010
www.endo-tribune.com
Vol. 5, No. 8
Apical microsurgery: the REB and REP
Part four of a six-part series
By John Stropko, DDS
The amount, or degree, of the
root-end bevel (REB) is of utmost
importance and should be precisely
planned in advance after considering
the overall crown/root ratio, presence of posts or other obstacles, the
root anatomy and the periodontal
status of the tooth. According to previous research, 98 percent of canal
system ramifications occur in the
apical 3 mm.1
If the bevel is long (traditionally
25 degrees to 45 degrees) an excessive amount of root structure would
have to be removed to include the
apical 3 mm on the palatal, or lingual, part of the root’s apical canal
system (especially in roots with multi
canals). If the bevel is closer to 0
degrees, the lingual 3 mm is easier to
remove; more root structure can be
conserved, improving the crown/root
ratio. With a long bevel, there is also
an increased risk of completely missing some important palatal or lingual
anatomy, especially if the operator is
in any measure trying to be conservative in order to preserve as much
crown/root ratio as possible (Fig. 1).
The long bevel creates a spatial
problem that is generally impossible
for the operator to overcome while
trying to visualize the true long axis
of the canal system (Fig. 2). The
longer the bevel, the greater the
tendency is for the operator to leave
more of the palatal, or lingual, aspect
of the root intact. Because it is difficult to visualize the long axis of the
tooth, the resultant retroprep is not
as likely to be within the long axis of
the canal.
This concept is of utmost importance and is the primary reason that,
on occasion, the retroprep unintentionally perforates to the lingual or
palatal (Figs. 3a, 3b).
Another important consideration
is, with a bevel as close to 0 degrees
as possible, the cavo-surface marginal dimensions (bet you haven’t heard
that term in awhile!) of the root
end preparation will be considerably
decreased. Therefore, the restoration
will be easier to place and have less
chance of leakage.
The root anatomy is especially
important when there are more than
two canals in one root. This occurs
most commonly in maxillary bicusg ET page 4B
Fig. 1: Illustration of the effect that different bevel angles have on root length and
including the missing of potential lingual anatomy. (Photos/Provided by Dr. John
Stropko, unless otherwise noted.)
3-D imaging and endodontics: educated
guess becomes scientific decision
By Harout Barsemian, DMD
As an endodontist, I was trained
to get to the root of the problem.
While this is literally my job and my
passion, in the past it has also been
a source of frustration. Conventional
2-D images did not provide enough
data to make scientific decisions
regarding diagnosis and treatment
planning.
With some 2-D images, rather
than diagnosing, it felt like I was
just guessing. My recent investment in a 3-D medium field-of-view
cone-beam scanner (Gendex GXCB500™) has changed my frustration
into realization and enabled me to
become a more conscientious practitioner.
An endodontic diagnosis depends
upon many factors, such as the experience of the clinician, anatomical
limitations such as thickness of the
cortical bone, positioning of the
Fig. 1: Pre-op and post-op (two months post-treatment) 2-D periapical X-rays
showing healing of endodontically treated first molar
Fig. 2: 3-D scan views —
partial of reconstructed
pan, axial view and
mesio-distal crosssectional slices revealing
extent of destruction
from infection to the
inferior alveolar nerve
and through the buccal
cortical bone.
apical abscess to the cortical bone,
zygomatic bone and sinus and proximity of neighboring teeth. With 2-D
X-rays, often these structures are
superimposed on one surface.
Research in the endodontic field
indicates that CBCT showed significantly more lesions (34 percent)
than periapical radiography. In
some infection cases, general dentists often delayed treatment due to
lack of supporting evidence on a 2-D
X-ray. With 3-D views, we can make
an immediate scientific decision. For
example, many endodontic patients
who suffer from chronic sinusitis
find that the ideology is really related to the teeth. Sadly, many have
already given up on treating the
problem and have learned to live
with their post-nasal drip forever.
After implementing the conebeam system, not a day passes when
g ET page 2B
[2] =>
2B
News
Endo Tribune | August 2010
ENDO TRIBUNE
f ET page 1B
I take a scan that I don’t find other,
less obvious contributing factors. I
find canals that were left untreated
by previous practitioners; complicated canal systems and unusual
anatomy; and other teeth or structures that need immediate attention outside of the field of interest.
Deciding whether resorption cases are interior or exterior sometimes became a guessing
game that took several X-rays to
determine if the damage was even
repairable.
With software, such as Anatomage’s Invivo5™, it is much easier
to establish if a tooth is cracked.
The ability to colorize in this software makes detecting the crack,
although still tricky, much easier.
In trauma cases or root fractures,
the 3-D scan clearly shows displacement or a bony fracture. In
the case of calcified canals, I can
acquire a mid treatment image
with the CBCT and define the
exact direction of the canal.
After diagnosis, all of the scientific evidence is vital for surgical confidence. Now, I feel more
assured about my patients’ safety.
With the guesswork involved with
2-D X-rays, I endured the uncertainty of not knowing the proximity of anatomical structures. In the
case of separated instruments, I
can locate the exact position of
the instrument for a less stressful
surgery.
Cone-beam radiography helps
me to avoid potential unwelcomed surprises during surgery.
For example, one patient came to
me with persistent swelling. While
the post-op 2-D PA image showed
healing (Fig. 1), the cone-beam
scan showed an area of very large
infection extending to the inferior alveolar nerve with extensive
cortical bone destruction (Fig. 2).
This was vital pre-surgical information.
With another patient who was
suffering from intense pain from
a tooth that was heavily restored
with a very large periapical rarification, I decided to do an apicoectomy to provide immediate relief.
On a 2-D X-ray, all appeared to be
simple (Fig. 3); however, because
the problem was on a posterior
tooth, I decided for safety sake to
ET
The World’s Endodontic Newspaper · U.S. Edition
Publisher & Chairman
Torsten R. Oemus
t.oemus@dental-tribune.com
Vice President Global Sales
Peter Witteczek
p.witteczek@dental-tribune.com
Chief Operations Officer
Eric Seid
e.seid@dental-tribune.com
Group Editor & Designer
Robin Goodman
r.goodman@dental-tribune.com
Editor in Chief Endo Tribune
Frederic Barnett, DMD
BarnettF@einstein.edu
International Editor Endo Tribune
Prof. Dr. Arnaldo Castellucci
Fig. 3: 2-D periapical X-ray of endodontically treated second molar
Managing Editor/Designer
Ortho Tribune & Show Dailies
Kristine Colker
k.colker@dental-tribune.com
Online Editor
Fred Michmershuizen
f.michmershuizen@dental-tribune.com
Account Manager
Humberto Estrada
h.estrada@dental-tribune.com
Fig. 4: 3-D scan views — partial of reconstructed pan, mesio-distal crosssectional slices revealing the destruction far to the lingual and the thickness of buccal cortical bone with proximity to the inferior alveolar nerve.
acquire a CBCT scan.
The 3-D view showed that the
infection was so far in lingually
(Fig. 4) that a very thick layer of
cortical bone had to be removed,
and the positioning of the inferior
alveolar nerve was so coronal that
paresthesia could also have resulted in this case.
Because of the scientific data
gathered from the cone beam, I
have begun to get referrals from
forward-thinking colleagues. I put
scans on CD and print out reports,
so they, too, can have as much
information as they need to provide
the best care for their patients.
My scientific mind doesn’t like
to make guesses, even educated
ones. Cone beam gives me the
facts, so that I can accomplish my
ultimate goal — getting to the root
of the matter, not by trial and error,
but by using science and facts. ET
ET About the author
Dr. Harout Barsemian attended the
University of Montreal for his dental
degree and obtained his endodontic
training at the University of Medicine
and Dentistry of New Jersey. He has
lectured and was a part time instructor at the University of PennsylvaniaDepartment of Endodontics and is
on the teaching staff of Morristown
Memorial Hospital Dental Clinic.
Barsemian is in private practice in
Morristown and Westfield, N.J.
Corrections
Endo Tribune strives to
maintain the utmost accuracy in its news and clinical reports. If you find
a factual error or content that requires clarification, please report the
details to Managing Editor
Sierra Rendon at s.rendon@
dental-tribune.com.
Managing Editor/Designer
Implant, Endo & Lab Tribunes
Sierra Rendon
s.rendon@dental-tribune.com
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© 2010 Dental Tribune America.
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publishers also do not assume responsibility
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Editorial Advisory Board
Frederic Barnett, DMD (Editor in Chief)
Roman Borczyk, DDS
L. Stephen Buchanan, DDS, FICD, FACD
Gary B. Carr, DDS
Prof. Dr. Arnaldo Castellucci
Joseph S. Dovgan, DDS, MS, PC
Unni Endal, DDS
Fernando Goldberg, DDS, PhD
Vladimir Gorokhovsky, PhD
Fabio G.M. Gorni, DDS
James L. Gutmann, DDS, PhD (honoris
causa), Cert Endo, FACD, FICD, FADI
William “Ben” Johnson, DDS
Kenneth Koch, DMD
Sergio Kuttler, DDS
John T. McSpadden, DDS
Richard E. Mounce, DDS, PC
John Nusstein, DDS, MS
Ove A. Peters, PD Dr. med dent., MS, FICD
David B. Rosenberg, DDS
Dr. Clifford J. Ruddle, DDS, FACD, FICD
William P. Saunders, Phd, BDS, FDS, RCS Edin
Kenneth S. Serota, DDS, MMSc
Asgeir Sigurdsson, DDS
Yoshitsugu Terauchi, DDS
John D. West, DDS, MSD
[3] =>
ENDO Tribune | June 2010
x 3B
[4] =>
4B
Clinical
Endo Tribune | August 2010
f ET page 1B
pids and in the mesial roots of nearly
all molars. It has been shown that as
many as 93 percent of the MB roots of
the max. First molars have a second
(MB2) canal.2 However, the operator
has to be constantly aware that multiple canals can occur in any root, no
matter what tooth is being operated
on. If there is an isthmus present, it
can usually be seen with the OM if
the root has been adequately beveled
and stained with methylene blue.
The refinement of the bevel is best
accomplished with a surgical length
1171 carbide-tapered fissure bur
(Brassler) in a 45-degree handpiece
(SybronDental). These handpieces
have no air exiting from the working end, which nearly eliminates the
possibility of an air emphysema, or
air embolism, beneath the flap.
A standard high-speed handpiece
should never be used for the above
reason. On occasion, the refinement
of the bevel can cause additional
bleeding due to some enlargement
of the crypt. The operator should
address any newly created crypt
management problem before proceeding any further. Remember that
it is of utmost importance to fully
complete one step before proceeding
to another!
After the REB is refined and crypt
management is completely under
control, the apical surface is rinsed
and dried with a Stropko Irrigator
(www.stropko.com). The clean and
dried surface is then stained with
methylene blue. It is important to
allow the methylene blue to remain
on the tooth for just a short period of
time before gently rinsing and drying again to enable inspection of the
stained surface.
Normally, a fresh, white piece of
Telfa is reinserted for better lighting.
If there are any fractures, presence
of isthmus tissue or accessories present, the staining will greatly enhance
the operator’s ability to visualize
them. Also, the methylene blue will
stain the periodontal ligament and
enable the operator to be sure the
apex has been completely resected.
(Fig. 4) If there is an accessory canal
present, the easiest answer is usually to bevel past it and restain. Or,
on occasion, the accessory can be
“troughed out,” leaving the bevel as
is.
When two canals are present in
the same root, it is necessary to
prepare for an isthmus between the
two canals even if the staining didn’t
reveal one. It has been shown that in
the mesiobuccal roots of the maxillary first molars with two canals,
the 4 mm section displayed a partial
or complete isthmus 100 percent of
the time.3 This combined with the
finding in the same root in maxillary
molars, that two canals present clinically at least 93 percent of the time
in the mesiobuccal root of the maxillary first molar, lends importance to
always prepare isthmus area of the
REB.2
Although staining doesn’t always
reveal the presence of an isthmus, it
may lie just below the surface, only
to be exposed during the remodeling
process of the surface of the beveled
Fig. 2: Long bevel with round bur
preps, demonstrating angulation
and orientation problems, courtesy
of Dr. Gary Carr.
Figs. 3a, 3b: Inadequate and acute 45-degree bevel clearly shows how perforations
can occur and canals can be missed. Fig. 3a is the surgeon’s view from the buccal.
Fig. 3b is what actually occurred but was completely missed by the operator.
Fig. 4: Staining allows the operator to be sure of complete root resection,
and to see if there is an isthmus, accessory or fracture present.
root that normally takes place during
the healing process. (Fig. 5) The rule
is to always prepare an isthmus when
there are two canals in one root.
The preparation of the root-end
preparation (REP) is best accomplished using ultrasonics. There are
many different ultrasonic units available. For the most part, they are all
dependable and have a good service record. There are multitudes of
ultrasonic tips to choose from. The
newer diamond coated and vented
tips (ProUltra Tips from DENTSPLY
Tulsa Dental or KIS Tips from Obtura/Spartan) are much more efficient
and especially good at removing
gutta percha.
The most important consideration
is not the brand of the ultrasonic unit
or type of tip but how the instrument
is used. The tendency for the new
operator is to use the ultrasonic in
the same manner (pressure-wise) as
the handpiece. The secret is to start
at a low power setting and use an
extremely light touch! The lighter the
touch, the more efficient the action of
the tip will be.
The correct amount of coolant is
also important. If too much spray is
used, visibility and cutting efficiency
are both decreased. If too little spray
is used, the necessary amount of
cooling will not be available and
overheating and/or micro cracks can
be the result.
The occasional left and right,
variously angled tips are necessary
on occasion, but in most cases, the
anterior type tips will suffice. If the
canal is large and/or filled with gutta
percha, a larger, coated tip can be
used most efficiently. The key is to:
1.) slow down; 2.) be gentle; 3.) use
a light, brushing movement; and 4.)
carefully regulate the power setting
of the ultrasonic unit. The power setting will vary greatly depending on
the tip being used and nature of the
preparation task at hand.
For the preparation of an isthmus,
an uncoated, fine pointed tip (CT-1
by SybronEndo) is inserted into the
ultrasonic and used to create a precise series of multiple “dots” on the
stained or “imaginary” line between
the two canals. For the DOT Technique, the ultrasonic unit is set at a
low power setting but inactivated,
water spray is turned off, a CT-1
tip is placed exactly where desired
and the rheostat is “tapped” for just
an instant. The process is repeated
again, and again, as many times as
necessary, until there are a series
of “dots” (Fig. 6a). Then, while the
water spray is still off, the dots are
gently connected to create the initial, shallow but precise “tracking
groove” (Fig. 6b).
The DOT Technique is of great
value, especially when there is concavity present and the width of the
beveled root is very thin mesial to
distal. The resultant groove serves as
a definite guide for the completion of
the isthmus portion of the REP. Then
with the water spray turned back on
and the power increased slightly, a
pointed, coated tip can be used more
aggressively to deepen the tracking
groove. In this manner, accuracy is
completely controlled and there is
no chance of “slipping off” while
preparing the isthmus in a very thin
root. On occasion, if the walls of the
prep become too thin, further beveling may be necessary.
Occasionally throughout the REP
process, it is important to use the
Stropko Irrigator to rinse and dry
the REP to be sure it is kept within
the long axis of the canals and all
debris is being removed as planned.
Various sizes of micro-mirrors, or an
Endoscope, are used to periodically
inspect the preparation and confirm
accuracy.
A pre-cut and pre-bent 25 gauge
endodontic irrigating needle (Monoject) works well for this purpose. The
notched end is removed by rapidly
bending the end one-third back-andforth with a Howe Pliers. The needle
inserted into the Stropko Irrigator is
then bent similar to the ultrasonic
tip to be used for the REP (Fig. 7).
Always keep in mind that cleanliness
and dryness are essential for good
visibility when using the OM.
Of particular interest is the buccal aspect of the internal wall of the
REP. Dr. Rubinstein was the first to
point out that often this area is not
debrided due to the angulation of the
ultrasonic tip within the canal system during the REP. If there is some
gutta percha “streaming up” the side
of the wall, and the preparation is
finished, the best thing is to take
a small plugger and fold the gutta
percha coronally so the wall is clean
once more. It is usually futile to try
to “chase after” the gutta percha with
an ultrasonic tip.
The ideal REP should be: 1.) within the long axis of the canal system,
2.) have parallel walls, 3.) be at least
3 mm in depth (including the isthmus portion of the preparation), 4.)
adequately extended to include any
buccal/lingual variations of the canal
system, 5.) be clean (free of a smear
layer) and 6.) dry and ready to accept
any type root-end filling material.
After completion of the REP, it
should be rinsed and dried once
more with the Stropko Irrigator. The
REP is re-inspected, using micromirrors and the varying powers of
the OM and/or Endoscope, to be
sure it is clean and within the long
axis of the canal system. At this time,
the REP is etched with blue 35 percent phosphoric acid gel (Ultra-Etch
by Ultradent) to remove the smear
layer. After 15-20 seconds, the REP is
thoroughly rinsed and dried with the
g ET page 6B
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ENDO Tribune | August 2010
Opinion 5B
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Clinical
Endo Tribune | August 2010
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Stropko Irrigator and re-examined
with the OM.
If all is as desired, a 15-second
rinse with 2 percent chlorhexidine
will help eliminate any residual
organisms present. One more gentle
rinsing and drying with the Stropko
Irrigator and the REP is ready for the
root-end fill (REF).
In the next issue, we will discuss the final two parts remaining
to achieve predictable apical microsurgery. Part 5 will discuss “Retrofill
materials and techniques.” Part 6
will discuss “Sutures, suturing technique and healing.”
To read Parts 1–3 again, visit www.
dental-tribune.com/articles/content/
scope/specialities/region/usa/id/929. ET
ET About the author
Fig. 5: An illustration of an isthmus,
lying just below the surface that
would not be evident, even after
staining with methylene blue
Fig. 6a: The series of ‘dots’ permit easy
and accurate preparation of an isthmus in a root end that is very thin.
References
1. Kim S. Surgical endodontics. In:
Cohen S, Burns RC. Pathways of
the pulp. St Louis: Mosby Co, 2002;
707.
2. Stropko J. Canal morphology of
maxillary molars: Clinical observations of canal configurations. J
Endod 1999; 25(6): 448-450.
3. Weller R, Niemczyk S, Kim S. Incidence and position of the canal
isthmus. Part I. Mesiobuccal root of
the maxillary first molar. J Endod
1995; 21: 380-83
Fig. 6b: While still dry, the ‘dots’ are
connected until there is a shallow,
but definite ‘tracking groove.’
Fig. 7: A modified and pre-bent needle
is used to clean and dry the REP for
good vision.
Dr. John J. Stropko received his
DDS from Indiana University in 1964,
and he practiced restorative dentistry
for 24 years. In 1989, he received a
certificate for endodontics from Boston University and recently retired
from the private practice of endodontics in Scottsdale, Ariz.
Stropko is an internationally
recognized authority on microendodontics. He is the inventor of the
Stropko Irrigator, has published in
several journals and textbooks and
is an internationally known speaker.
He is the co-founder of Clinical Endodontic Seminars and and was an
instructor of microsurgery for the
endodontic courses presented at the
Scottsdale Center for Dentistry. Stropko, and his wife, Barbara, currently
reside in Prescott, Ariz. You may contact him at topendo@aol.com.
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ENDO Tribune | June 2010
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