Endo Tribune U.S. No. 8, 2012

Well-thought-out simplicity leads to superior obturation / Redefining endodontic education

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ENDO TRIBUNE
The World’s Endodontic Newspaper · U.S. Edition

september 2012 — Vol. 7, No. 8

Clinical opinion

Well-thought-out
simplicity
leads to superior
obturation
By Barry Lee Musikant, DMD

n light of recent research that
clearly demonstrates the production of micro-fractures as a result
of rotating NiTi instrumentation1-4 ,
we should take a cautionary note when
using any combination of high pressure
and heat when obturating canals.
What starts out as small micro-fractures has the potential to propagate to
larger and larger fractures, ultimately
producing a full vertical fracture of the
root. We want to avoid this possibility
and the causative agents that can exacerbate this potential. Yet at the same
time, we wish to only obturate a canal
that is fully cleansed, be it oval or round,
in cross-section.
The research tells us that to fully
cleanse a canal, we must have a minimum apical preparation of 35 to provide for effective irrigation5. Without
effective irrigation, the most machined
canal will still have remnants of organic
debris that may be harboring bacteria.
Not only is a 35 preparation the minimum requirement, but the 35 apical
preparation must extend to all the walls
of the canal.
It is not enough to have it centered
within an oval canal and not touching
the walls constituting the major diameter6. In short, if we start with an oval
canal, we want to end up with a larger
version of that same oval canal. What we
definitely do not want is the conversion
of an oval canal into a wide round canal,
which in the process may undermine
the strength of the walls constituting
the minor diameter of the root.
Once we have produced a canal space
that has removed the bulk of the dentinal debris and provided for adequate
irrigation, we want to then choose the
appropriate irrigants to most effectively
kill any remaining bacteria and digest
any organic debris remaining. Seventeen
percent EDTA removes the smear layer
and opens the dentinal tubules as well
as provides an effective lubricant for the
apically negotiating instruments.
We follow 17 percent irrigation with 6
percent NaOCl, a solution that digests
organic debris and kills most bacteria.
By using the 17 percent EDTA first, the
resulting open tubules allow for greater penetration of the 6 percent NaOCl
where it may attack bacteria that have
penetrated the tubules as deep as 200
microns. Two percent chlorhexidine
(CHX) is valuable in non-vital cases
” See OBTURATION, page B2

www.dental-tribune.com

Redefining endodontic education
L. Stephen Buchanan discusses new ways to help dentists learn
By Fred Michmershuizen, Managing Editor

In an interview with Endo Tribune, L. Stephen Buchanan, DDS, FICD, FACD, of Dental
Education Laboratories discusses his new
TrueTooth™ replicas and how they can be
used by all dentists to master technique,
his new website offering videos of clinical
cases, and his upcoming speaking engagement at the ADA meeting in San Francisco.
What is new with you?
I’m glad you asked. Check out these 3–Dprinted tooth replicas (Figs. 1,2). I wanted to
do this 20 years ago, but I had to wait for stereo-lithography to advance to the sophisticated level it is today before it was possible
to make these at a high enough resolution
(0.1 mm layers) to accurately re-create the
experience of working inside a tooth. Now
that we can, procedural training in dentistry will never be the same again.
That’s a pretty bold statement.
It is a bold statement, but it’s true. Before
this, our best training experiences — short
of working on a patient — were in extracted teeth. While it is convenient to practice
endo procedures in teeth without their
previous owners to deal with, working in
extracted teeth is limiting in many ways,
and I’ve often thought we could do better.
In extracted teeth, we have the problems
of hidden anatomy and a one-off experience, meaning that if you botch practice in
an extracted tooth containing a root canal
morphology that represents a certain procedural endodontic challenge, you are done.
You don’t get to try and try again until you
learn that specific skill. You had one opportunity to learn a new trick, but you now have
to randomly cross similar morphology in
another extracted tooth to give another try,
or hope for the best if it is encountered in a
patient before you figure it out.
With these clear and solid-color TrueTooth replicas, course attendees and dental
students can attempt a procedure again
and again — in exactly similar replicas —
until they learn that particular skill cold.
How do these new tooth replicas compare
with other, similar tools?
Compared to clear plastic endo blocks we
have traditionally used, they are better in
every way:
• They are printed with a heat-resistant
polymer, so they do not melt and gum up
high-speed burs or grab rotary files.
• They have real root canals inside
them. They are replicas, not models.
• All the other models I’ve seen have
over-simplified, soda-straw-like canal
morphology — ridiculously simple with
overly large terminal diameters.
The true complexity of roots and the root
canal systems inside them has never been
re-created in any type of training model.
With 3–D-printed training replicas, we
can make the same, exact, perfect tooth

Fig. 1: A TrueTooth 3–D replica available from www.DELendo.com. Photos provided by L. Stephen Buchanan

form over and over, so dentists can practice
again and again until they get consistently
good results with a given technique in a
given anatomic challenge. We even have a
patent-pending process for these TrueTooth
replicas to have simulated pulp tissue that
dissolves with sodium hypochlorite irrigating solutions. If you irrigate these replicas
effectively, you will see one or more lateral
canals filled upon completion.
That’s very cool. I guess it wasn’t that bold
a statement. What else is new with you?
We also have an all-new website, www.
DELendo.com, which just went live at the
beginning of September. I’m very proud
of the diligence and creativity my team
at Dental Education Laboratories applied
to this project.
This time, besides the quality of the
site design, the most significant parts of
DELendo will be the case contributions of
others. And with streaming video servers
in place, you will see clinical case videos

from some of the best endodontists in
the world.
It sounds like DELendo is a cross between
YouTube and Apple TV.
Yes. We have lots of exceptional free content, but we also have five- to 15-minute
educational lectures, OnTopic™, and fully edited clinical case videos, called From
The Op™, by myself and others, available
for a small viewing fee, which helps offset some of our production costs.
The site offers small, inexpensive, bitesized educational segments. This is how
the Internet is changing education. More
and more, we will see courses designed
for the way people prefer to learn — in
chunks. It is a different way to look at educational curricula, but the feedback we
are getting is over the top positive.
I’ve described our new TrueTooth procedural replicas, and our interactive stream” See INTERVIEW, page B3

[2] =>

clinical opinion

B2
“ OBTURATION, Page B1
where it is most effective against E. facaelis, a bacteria most associated with
recurrent root canal failures. To use CHX
without producing a troublesome precipitate, all remnants of both EDTA and
NaOCl must be removed from the canals
first. This is best done by irrigating the
canals copiously with sterile water or anesthetic solution.
Only after the canals are properly
shaped and irrigated are we now ready
for canal obturation. Much creativity
has gone into ways to obturate canals.
One school believes in thermoplasticing
gutta-percha so it adapts better to the
canal shape as it drives a thin cement
interface into an intimate fit with the
canal walls.
Thermoplastic oburation can be accomplished with a carrier-based system,
various heating elements or glue guns.
The Achilles’ heel of all these systems is
the contraction that occurs to the guttapercha as it cools to body temperature
after it has been placed within the canal7. Research has shown that thermal
contraction continues for a minimum
of 45 minutes after the heat has been
applied.
Techniques that call for the application of pressure for 10 seconds to compensate for thermal contraction recognize that gutta-percha will shrink as
it cools, but the technique applied to
compensate for that shrinkage is ineffective given the long-term contraction
that actually occurs. Thermoplasticized
gutta-percha will drive the cement into
an intimate relationship with the canal
walls, but will then contract, leaving a
void between the laterally displaced cement and the shrinking gutta-percha.
For these reasons I am not an advocate
of thermoplastized systems.
Whether the interface of cement is
thick or thin, we are relying on the cement as the actual seal. In effect, the gutta-percha or its substitute is merely a carrier and a driver of the cement. It is the
cement that is most critical in providing
a good seal. With the cement itself the
most important factor in creating an effective seal, the properties of the cement
are most important.
I prefer epoxy resins over other types
of cement for the following reasons:
1) Epoxy is highly flowable, giving it the
ability to penetrate the dentinal tubules
far deeper than other cements.
2) Epoxy cement does not shrink upon
polymerization. This is an important
difference compared to methacrylate
cements that shrink 4 to 7 percent with
polymerization.
3) Epoxy resin cements bind to both
gutta-percha and dentin physically and
chemically further enhancing the seal.
4) Epoxy resins, being polymers, are
highly resistant to water degradation.

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
Fred Michmershuizen at
f.michmershuizen@dental-tribune.
com.

Fig. 1 Photos/Provided by Barry Lee Musikant,
DMD

Fig. 2

This is not the case for particulate cements such as ZOE, calcium hydroxide
and glass ionomers.
5) Epoxy resins are innately anti-bacterial.
6) While set epoxy is harder than gutta-percha, it is still softer than dentin, allowing its lateral removal at a later date
if a post-hole or retreatment is required.
7) Long-term leakage studies have
shown epoxy resins to provide for a longterm seal.
While new cements are being introduced, their overall properties do not
match those of epoxy resin. The bioceramic cements do not flow well and are
almost impossible to remove. Recent
research shows they leak more than
conventional cements. It is not surprising that they are hard to remove. Their
chemical structure is similar to that of
concrete, and they set with a similar
hardness. I know of no other cements
that represent a set of superior properties to that of epoxy resin.
Almost as important as the cement
itself is the delivery system. No matter
how good a cement, it is of limited value
if it cannot properly coat the entire canal without driving excess cement over
the apex. To maximize canal coating
while minimizing extrusion beyond the
apex, we developed the bidirectional
spiral where the majority of the coronal
flutes drive the cement apically and the
three most apically placed flutes then
drive the cement back coronally.
The result of such a design is an instrument that generates two flows of
cement, one in the apical direction and
one in the coronal direction. When these
two flows of cement collide, they are
driven laterally against the canal walls.
While the bidirectional spiral is rotating
at approximately 1,500 revolutions per
minute, it is also being used with an upand-down motion.
Consequently, the cement is driven laterally against the canal walls throughout the canal’s entire length. Knowing
that excess cement will escape coronally
rather than being driven apically gives
the dentist the ability to thoroughly

Endo Tribune U.S. Edition | September 2012

flood the canal space with cement.
When the prefitted master point is then
liberally coated with cement and placed
into the canal, most of the cement will
be driven laterally, with excess cement
escaping coronally. The flow of the cement is superior to that of the flow of
any thermoplasticized gutta-percha
system (Figs. 1, 2). Of greater importance
is the fact that it is a room temperature
obturation system.
Unlike thermoplastic systems where
the obturation materials must cool to
body temperature, shrinking 4 to 7 percent in the process, a room temperature
system will warm to body temperature,
expanding about 1.75 percent in the
process. While expansion is not great,
it is heading in the right direction and
can only improve the seal. It should be
added that the small amount of expansion that does occur happens before the
cement has set, preventing any lateral
stresses to the root.
A final point should be made about
the use of lateral condensation. Again,
given what we know about the generation of potential micro-fractures already
produced by the use of rotary NiTi systems, it is most important to minimize
the amount of lateral stresses produced
when condensing the gutta-percha fill.
For this reason, I never use more pressure
than the weight of my hand when creating space for subsequent well-coated lateral points.
A secondary benefit is that we never
apply enough pressure to distort the
shape of the gutta-percha point. This is
important because gutta-percha, similar
to rubber, would rebound to its original
shape if it were distorted, creating a void
where the cement has already been displaced.
Perhaps what becomes most apparent
is that we can produce a superior seal by
adhering to simple principles, namely
flooding the canal with a cement known
for its superior properties using a patented bidirectional spiral that allows full
coating without the extrusion of excess
cement apically. With this unique tool
driving a room temperature highly flowable epoxy resin cement, we can achieve
an excellent seal with high predictability
and low cost.
For more information on these materials and the way they are used, please contact me at info@essentialseminars.org.
Editorial Note: A complete list of references is available from the publisher.

Barry Lee Musikant,
DMD, is a member
of the American Dental Association, American Association of En-

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All rights reserved.
Dental Tribune American strives to maintain the
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Editorial Board
Frederic Barnett, Editor in Chief
Dr. Roman Borczyk
Dr. L. Stephen Buchanan
Dr. Gary B. Carr
Prof. Dr. Arnaldo Castellucci
Dr. Joseph S. Dovgan
Dr. Unni Endal
Dr. Frnando Goldberg
Dr. Vladimir Gorokhovsky
Dr. Fabio G.M. Gorni
Dr. James L. Gutmann
Dr. William “Ben” Johnson
Dr. Kenneth Koch
Dr. Sergio Kuttler
Dr. John T. McSpadden
Dr. Richard E. Mounce
Dr. John Nusstein
Dr. Ove A. Peters
Dr. David B. Rosenberg
Dr. Clifford J. Ruddle
Dr. William P. Saunders
Dr. Kenneth S. Serota
Dr. Asgeir Sigurdsson
Dr. Yoshitsugu Terauchi
Dr. John D. West

dodontists, Academy
of General Dentistry,
the Dental Society of
New York, First District
Dental Society, Academy of Oral Medicine,
Alpha Omega Dental
Fraternity

and

the

American

Society

of Dental Aesthetics. He is also a fellow of the American College of Dentistry (FACD). As a partner
in the largest endodontic practice in Manhattan,
Musikant’s 35-plus years of practice experience have
established him as one of the top authorities in endodontics. To find more information from Musikant,
visit www.essentialseminars.org, email info@essentialseminars.org or call (888) 542-6376.

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[3] =>

Endo Tribune U.S. Edition | September 2012

“ INTERVIEW, Page B1
ing video site, DELendo, but in terms of
new methods of training dentists, we’ve
taken it even further. By year’s end we will
be launching the first remote procedural
training course ever given in dentistry,
called DIY/CE™, which stands for “do-ityourself continuing education.”
Now that we can now print high-resolution replicas of dental anatomy, we can
control the anatomy within which we
teach our course attendees. Since we know
the anatomic challenges, we know pretty
much all the different ways treatment
may end up, so we can show dentists what
happened during their treatment and how
they can improve their next attempt at
clinical endodontic perfection.
So now a dentist can take a hands-on
course in his or her own office?
Yes, but the advantage of this concept is
not just the dollar savings from avoiding
the air travel, hotel and course costs. One
of the coolest aspects is that procedural
training can be done with your assisting
staff there, so they are training simultaneously as you are. The feedback from dental
students and dentists who have trained in
DEL’s TrueTooth training replicas has been
enthusiastic, with unanimous agreement
that printed tooth replicas are superior to
extracted teeth for endodontic procedural training because they are:
• Readily available — no more collecting teeth before training
• Clean — no biohazards to deal with
• Exactly the right anatomic challenge
for teaching every type of procedure
• Reproducible — so learning how to
manage a particular procedural challenge can be accomplished in a more iterative and in a less random manner.
• Ideal for board exams and dental
school practical exams, because grading
becomes standardized.
You’re one of the featured speakers at the upcoming ADA Annual Session. Can you give us
a preview of what you’ll be presenting?
Sure. My all-new presentation is titled
“The Art of Endodontics: Everything Has
L.

Stephen

Buchanan, DDS,
FICD, FACD, was
valedictorian

his class at the
University of the
Pacific School of
Dentistry, and he
completed

the

endodontic graduate program at
Temple University
in Philadelphia in
1980. He began pursuing 3-D anatomy research
early in his career, and in 1986 he became the first
person in dentistry to use micro CT technology to
show the intricacies of root structure. In 1989 he
established

Dental

Education

Laboratories,

through which he has lectured and conducted participation courses around the world. Buchanan
holds a number of patents for dental instruments
and techniques, including variably tapered shaping instruments for use in endodontics. He pioneered a system-based approach to treating root
canals. He is a diplomate of the American Board of
Endodontics. He maintains a private practice limited to endodontics and implant surgery in Santa
Barbara, Calif. Contact him at 1515 State St., Suite
16, Santa Barbara, Calif. 93101, (800) 528-1590 or
(805) 899-4529, info@endobuchanan.com, www.
DELendo.com, www.endobuchanan.com.

Interview

Changed but the Anatomy.” What’s different? Quite a bit, actually. Attendees will see
fresh clinical footage — shot with a stateof-the-art HD1080p video camera — that is
painted onto the screen at a resolution that
resembles looking through the microscope.
They will see new procedures, such as rotary
negotiation, guided-bur access preps, singlefile GTX shaping, single-cone backfilling
and many more. In the spirit of “Everything
Has Changed,” most of the video clips were
chosen from recent clinical cases.
Sounds like you’ve put a lot of effort into
your new lecture.
Yes, it’s a top-to-bottom redesign of my
full-day presentation. For the past year
and a half I have been working on “Everything Has Changed,” but it was worth it
when I recently presented at the University of Texas at Houston. Course reviews
from attendees averaged 4.75 points out of
5, with comments like, “Best endo lecture
I’ve ever seen.” At Dental Education Labo-

Fig. 2: A TrueTooth 3–D replica available from www.DELendo.com.

ratories, our mission statement is to meet
and exceed our course attendees’ expectations. Hearing and reading that kind of
response makes it all worthwhile.
What is your favorite thing to hear from a
course attendee?
That’s easy. My favorite compliment is to
meet a former student and hear him or
her say that attending one of my courses

changed their experience performing
endo procedures from being their least
favorite to the best part of their practice.
When are you presenting in San Francisco?
My all-day lecture at the ADA meeting is scheduled for Saturday, Oct. 20,
and I’ll be teaching a hands-on course
on Sunday morning, Oct. 21, where we
will be using TrueTooth replicas.
AD

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Well-thought-out simplicity leads to superior obturation / Redefining endodontic education

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