roots C.E. No. 1, 2021

Cover / Contents / Editorial / Coronal leakage prevention to improve endo success / Root canal irrigation using a laser / AAE21 goes ‘live & on-demand’ / Dr. John J. Stropko retires / Imprint

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roots
issn 2161-6558

the international magazine of

1

2021

_clinical
Coronal leakage
prevention

_technology
Root canal irrigation
using a laser

_meetings
AAE21: ‘Live &
on-demand’

International Edition • Vol. 11 • Issue 1/2021

endodontics

[2] =>

[3] =>

contents_ roots

I

page 08

roots

I editorial
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issn 2161-6558

Continuing education and changes
_John J. Stropko, DDS, Editor in Chief

the international magazine of

1

I clinical
08

International Edition • Vol. 11 • Issue 1/2021

endodontics

2021

 oronal leakage prevention to
C
improve endo success
_Gregori M. Kurtzman, DDS

_clinical
Coronal leakage
prevention

_technology
Root canal irrigation
using a laser

I technology

_meetings
AAE21: ‘Live &
on-demand’

18	Root canal irrigation using a laser

I on the cover

_Valerie Kanter, DMD

Using laser technology
available from Fotona
for root canal therapy.
(Photo/Provided by
Fotona)

I associations
20

Access to care program is launched

I meetings
21

AAE21 goes ‘live & on-demand’

I milestones
22

Dr. John J. Stropko retires

I about the publisher
23

_imprint

page 18

page 20

page 21

		

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editorial _ roots

Continuing education
and changes
How fortunate we are, to be members of such an incredible profession. In spite of the pandemic, the
opportunities to learn new and better techniques are always available. With our current e-technology, it
is possible to attend seminars, solely or as a group, anywhere in the world! So much is just waiting to help
us on our journeys. For those who are relatively new to our profession, I would like to take this opportunity
to share some significant changes that have occurred within the past 60 years.
Back in the mid ’50s, it was common for the dentist to stand up while treating patients while using a
foot to control the rheostat for the belt-driven, slow-speed (18-20K rpm) handpiece. Then in the early
’60s, a few practices were fortunate to have access to the new Bordan Airotor, an air-turbine, high-speed
handpiece that achieved an incredible 250K rpm! Teeth could be prepared in less time, but the same uncomfortable posture of standing up and using the foot-controlled rheostat was still the norm.
Over the next few years, the practice of dentistry was changing, especially the concern about the dentist’s operating posture. Sitting down to treat a patient became more of a standard, and this led to several
changes in office design and equipment. In 1967, my first office was equipped utilizing the latest design
and technology. But one of the first things we became aware of was the wasted time and energy for the
patient to use the cuspidor, so a high-speed evacuator system was installed to eliminate the problem. It
was an exciting time!
Most practices grew rapidly, and “busyness” followed along with the realization of a certain dissatisfaction with everyday work life. Some popular continuing education courses were concerned with practice
management. Management consultants could spend a few days at your office to enable the dentist(s) and
their staff to more efficiently utilize the time spent with patients. “If you always think the way you have
always thought, you will always get what you have always got!” Dental technology was advancing more
rapidly. To keep pace with all the advancements, C.E. courses became more and more available. And most
of the time after taking a course, additional investments had to be made for new materials, instruments or
equipment to utilize the new skills or techniques. For example, after one seminar at the Pankey Institute I
came home and bought loupes for magnification and a headlamp for improved lighting. C.E. courses were
definitely a “game changer,” and going into the office everyday became “fun again”!
It was not long before many states established mandatory minimum C.E. attendance requirements for
the doctors. Also, minimum requirements were instituted by the ADA and AGD for acceptance of those C.E.
courses. After 24 years of restorative practice I decided to become an endodontist, and in 1987 I became
a student once again and received my Certificate of Endodontics from Boston University in June 1989.
As a new specialist, just out of training, I knew there was so much more to learn. One of my biggest
concerns about my specialty training was that I did not learn anything different about apical surgery
than before I started. Fortunately, there were some good C.E. courses in our profession to learn from, and
I decided to start my journey.
One of my first endodontic C.E. courses was “Apical MicroSurgery,” presented by Dr. Clifford Ruddle
in Santa Barbara, Calif. As part of the two-day seminar, Dr. Gary Carr presented his work with the surgical operating microscope. The “hands-on” session using the SOM for the first time just blew me away!
Within two weeks after the course, I had my own SOM with an assistant’s scope attached, and we have
never worked without one since. My wife, Barbara, and I spent the next several years as visiting instructors
helping Dr. Carr at the Pacific Endodontic Research Foundation (PERF) in San Diego. Prior to the surgical

John J. Stropko, DDS
Editor in Chief

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I editorial_ roots
developed at PERF, it was common to leave the sutures in for
‘More advancements and technique
seven to 10 days, there was a significant amount of swelling, and narcotics
antibiotics were routinely prescribed. With the new procedures, using
changes are happening and
the SOM, sutures were removed in 24 hours, NSAIDs were prescribed and
antibiotics were usually not necessary.
The improved vision and direct lighting the SOM provided was the most
at an ever-increasing significant
advancement in dental treatment to date. To take advantage of
could now be done with the SOM, many new instruments were develrate. There are masters what
oped. Just a few examples were micro-scalpels, hemostats and ultrasonics.
Due to unavoidable splashing while using the air/water syringe, the simple
of our profession in every process of rinsing and drying conventional and surgical endodontic preparations led to the creation of the Stropko Irrigator, enabling precision and
for the procedure.
country of the world. control
During the 1990s, computer technology gradually replaced hard copy
records for patients, and scheduling became a more routine procIt is important to seek paper
ess. The influence of computers in the advancement of endodontics was
incredible! Many in our profession today don’t remember the “darkroom,”
small, closet-like room in our offices where the developing and fixing
them out and to study the
of radiograph films was done. One of the most profound changes in dental
technology was the advent of digital radiography. Cone-beam computed
under them.’
tomography (CBCT) became a huge asset for a better diagnosis, easier treatment and more predictable results. MTA was introduced as a new root-end
filling material and to be used for perforation repairs.
At the turn of the century, changes had become the norm. More predictable treatments for invasive
cervical resorption (ICR) were established. The minimally invasive technique for maintaining root structure
and strength during conventional treatment was adopted. New bioceramic materials and sealers were
developed. The GentleWave technique is one of the more recent developments to aid in the conventional
cleaning and disinfection of the canal system.
The most current “high-speed” handpieces operate at 400K rpm for precision work. For applications
requiring higher torque than a high-speed handpiece can deliver, a “low-speed” handpiece operating up
to a max of 40K rpm can be utilized. Today, the laser is starting to supplant the handpiece. The use of laser
low-level light therapy (LLLT) can be used postoperatively to decrease normal postoperative sequela and
speed up healing. As a result, the future of dentistry is looking more and more pain-free.
Over all these years, I have been privileged to enjoy numerous opportunities to present lectures and
seminars, visit hundreds of dental offices and make lasting friendships, both nationally and internationally. It was interesting to talk with different doctors and enjoy occasional “after-hours” casual conversations. When we were together, no matter the subject, it always ended up in dentistry! We are a curious
group for sure, and after watching some of the finest operators at work, it was obvious that the common
ingredient for excellence was the passion they had for what they did and how it should be done.
On a few occasions, I left an office I just visited and had the feeling that he or she should have retired
some time ago. My prayer became that I would know when to quit. It happened about 10 years ago. It was
a routine endodontic case. To finish the case to the level I always tried to achieve would have normally
taken no more than two hours, but instead it took me more than four hours. I suddenly realized that my
hand-eye coordination was not what it used to be, and my time had come to “put the handpiece down.”
More advancements and changes are happening at an ever-increasing rate. There are masters of our
profession in every country of the world. It is important to seek them out and to study under them. It is
imperative for practitioners to participate in as many C.E. seminars as possible. Some changes that have
to be made as the result of learning new techniques may seem complex and be a sizeable investment in
both time and money, but the rewards to yourself, your staff and your patients will make it all worthwhile.
So, do not delay, make the changes today!

John J. Stropko, DDS
Editor in Chief

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I clinical_ leakage prevention

Coronal leakage
prevention to improve
endo success
Author_Gregori M. Kurtzman, DDS, MAGD, FAAIP, FPFA, FACD, FADI, DICOI, DADIA, DIDIA

_Introduction
Endodontic failure has been associated with
coronal leakage within the canal system following
obturation. A more likely determinant of clinical
success or failure than apical leakage is leakage
from the coronal aspect of the tooth.1-3 This may
be the result of leakage of the core material and
restoration placed following endodontic treatment
related to recurrent decay. The patient may delay
placement of a crown on the tooth due to finances,
waiting on available insurance benefits or a lack of
urgency as the pain that led them to seek endodontic treatment has been eliminated.
Following obturation of the canal system, no
matter what our intentions are, patients may delay
restoration of the tooth that has been endodontically
treated. Time and financial constraints often influence when the final restoration may be completed.
Additionally, between appointments, an adhesive
material will prevent leakage and subsequent contamination of the canal system.
Recent advances in obturation materials have
demonstrated superior sealing of the canal system,
as the materials are insolvent in oral fluids that
plagued ZOE and CaOH-based sealers that were in
wide use for decades. Yet without addressing the
coronal aspect of the tooth following endodontic
treatment, endodontic failure still may occur related
to leakage originating coronally and progressing
between the obturation material and canal walls,
leading to apical pathology. Studies have confirmed
that overall success of root canal treatment relates
to a sound coronal seal.4-7 Regardless of the obtura-

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tion materials or method utilized, a properly cleaned,
shaped and obturated tooth should be permanently
restored as soon as possible.8

_Coronal leakage
The literature indicates that coronal leakage is a
major determinant of endodontic success or failure,
no matter what materials are placed into the canals
to obturate the canal system. When the coronal portion of the tooth is not sealed with materials that are
adhesive to tooth structure and are resistant to dissolution by oral fluids, over time endodontic failure
may be inevitable.
It is not uncommon for patients to present with
marginal decay around a crown on a tooth that has
had prior endodontic treatment. Those teeth having
had prior endodontic treatment do not have potential sensitivity that may be reported in a vital tooth
that may indicate a problem under the crown, so the
patient is not alerted to the need to seek dental treatment, allowing the leakage to progress. Coronal leakage may quickly lead to apical migration of bacteria
even when leakage is of a short duration. Progression
relates to what materials are present obturating the
canal system and in the coronal aspect of the tooth.
When the patient does present with marginal leakage related to recurrent decay, it might have been
ongoing for an extended period of time. This may
complicate treatment or may render the tooth nonrestorable, necessitating extraction.
The literature has reported that exposure of a
sealed canal system to artificial and natural saliva
may lead to complete bacterial leakage within two

[9] =>

clinical_ leakage prevention

Fig. 1

days.9,10 Dye leakage can occur in as little as three
days as reported in an in-vitro study.11-13 It has been
suggested that gutta-percha does not offer an effective barrier to crown-down leakage when exposed
to the oral environment.14-16 Additional studies on
using gutta-percha and various sealers indicate
that gutta-percha will allow bacterial leakage. But,
use of an adhesive sealer may significantly slow or
stop coronal-apical bacterial migration related to
adhesion of the sealer to the gutta-percha within the
obturated canal system.17
Staphylococcus, a gram-positive facultative
anaerobe, is the predominant bacteria found in endodontically treated teeth undergoing coronal leakage
with persistent apical periodontitis. This is followed
by Streptococcus and Enterococcus, both of which
are normal salivary flora.18,19 Coronal leakage, thus,
can provide a constant source of microorganisms
and nutrients that can initiate and maintain periradicular inflammation and may well be the largest
cause of failure in endodontic therapy.20
Endodontic obturation materials, no matter which
are utilized, will not prevent coronal microleakage
for an indefinite period of time.21 A sample of 937
obturated teeth in one study on teeth that had not
received restorative treatment during the previous
year reported that the technical standard of both the
coronal restoration and obturation were essential to
periapical health.22 It is not uncommon following endodontic treatment as a result of deficient composite
resin fillings and secondary caries under restorations
for coronal leakage to occur.23
Unfortunately, the endodontic obturation materials utilized over the past 50 years when challenged
coronally have shown that they do not prevent leakage.
A study reported on 45 teeth that were cleaned, shaped
and obturated using a lateral condensation technique
with gutta-percha and an endodontic sealer. The
coronal portions of the obturation materials were
placed in contact with Staphylococcus epidermidis
and Proteus vulgaris, with the number of days required
for these bacteria to penetrate the entire root canals
determined. More than 50 percent of those teeth in

Fig. 2

I

Fig. 3

the study became completely contaminated after a
19-day exposure to S. epidermidis, and 50 percent of
those treated teeth were also totally contaminated
when exposed to P. vulgaris at 42 days.24 AH-26 and
other commonly used sealers were compared after
45 days of exposure to oral fluids, and it was found
that none of the sealers was capable of preventing
leakage and coronal dye penetration.25
We can understand that the quality of the
obturation material and coronal restoration are
both essential to periapical health, as none of the
present-day root canal sealers may hermetically
seal “the root canal wall — gutta-percha obturation interface.” The importance of perfectly sealing
coronal restorations both between appointments to
complete endodontic treatment and following endodontic treatment before a permanent restoration
is placed needs to be emphasized and considered.26

Fig. 1_Severe coronal breakdown of
a lower molar requiring endodontic
therapy. (Photos/Provided by Dr. Gregori
M. Kurtzman)
Fig. 2_Coronal pre-endodontic buildup
achieved with canal projectors providing
individual straight-line access into each
canal.
Fig. 3_Temporary filling material has
been placed over the shortened canal
projectors placed back into the preendodontic buildup to seal the canals
between appointments to complete the
endodontic treatment.

_Pre-endodontic buildups
As has been outlined, coronal leakage is a major
contributor to endodontic failure.27,28 When significant coronal breakdown is present or replaced
by a previously placed non-adhesively bonded
direct restoration, a bonded core placed prior to
instrumentation/disinfection and obturation of
the canal system can greatly diminish the coronal
leakage potential both during and after endodontic treatment. Isolation of the pulp chamber can be
a challenging task when minimal coronal structure
remains, and endodontic treatment is required as
part of the oral rehabilitation (Fig. 1).
Coronal reinforcement has traditionally been
addressed following the endodontic phase.29 Yet a
coronal bonded buildup can simplify the endodontic phase, strengthening the remaining tooth structure, decreasing the potential for further damage to
the remaining tooth due to dam clamp placement
or functioning on the tooth before a full coverage
restoration can be placed. Sealing the pulpal floor
to the outer periphery of the tooth and surrounding
the canal orifices will decrease coronal leakage po-

		

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Fig. 4
Fig. 4_Temporary restoration using the glass ionomer
Fugi Triage Pink (GC America, Alsip, Ill.) to seal access.
Fig. 5_Placement of an immediate coronal restoration
with Fugi IX (GC America, Alsip, Ill.) glass ionomer
following endodontic therapy with evident periapical
lesion. (Courtesy of Dr. Martin Trope)
Fig. 6_Coronal seal has been maintained, allowing
apical healing of periapical lesion one year following
treatment. (Courtesy of Dr. Martin Trope)
Fig. 5

tential during and following endodontic treatment.
Following identification of the canal orifices and
caries removal prior to full instrumentation of the
canals, a gutta-percha cone can be placed into each
canal that has been instrumented in the coronal half
of the canal to a size 25 or greater. A dentin adhesive
is placed on all exposed surfaces with a microbrush
and is light cured, keeping light apical pressure on the
protruding gutta-percha cones in the canals. A dualcure activator that matches the dentin bonding agent
can be added (following manufacturers’ instructions)
should the practitioner so chose to ensure complete
curing of the adhesive on the deeper aspects of the
coronal portion of the endodontic access preparation.
Next, a dual-cure buildup material is injected
around the projector cones, backfilling from the
pulpal floor coronally. The placed build-up material
is light-cured and then allowed to complete selfcure in the deeper aspects for three to four minutes.
When the buildup material setting has been completed, the gutta-percha cones previously inserted
to prevent resin blockage of the canals is removed,
leaving straight-line access into each individual
canal (Fig. 2). The resin has not adhered to the guttapercha, so the cone is easily removed. Grasping the
protruding portion above the occlusal surface with
a locking hemostat can expedite cone removal and
allow placement of the rubber dam. Visualization of
the orifice is elevated to the occlusal plane instead of
deep within the tooth, and a bonded seal coronally
around each orifice is achieved.
When endodontic treatment cannot be completed at the initial visit, following calcium hydroxide
(CaOH) placement as a medicament into each canal,

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Fig. 6

a provisional temporary material is placed to seal
each projected orifice (Fig. 3). At the subsequent
appointment the temporary filling material is removed from each projected orifice at the occlusal
surface, and instrumentation of the canal system is
continued to complete endodontic treatment of the
canals. Should the practitioner, when restoring the
tooth, wish to place posts into the tooth, post space
preparation is simplified and misdirection of the post
preparation is minimized.

_Sealing the access via the coronal
restoration
Oral microorganisms have demonstrated an ability
to penetrate through various temporary restorative
materials, no matter how well-obturated the root canal system. Utilization of adhesive sealers may minimize coronal leakage, playing an important role in
leakage prevention. In addition, the importance of an
immediate definitive coronal seal should be emphasized following obturation of the canal system.30-32
A study of 70 extracted single-rooted mandibular
premolars to determine the length of time needed
for salivary bacteria to penetrate through three
commonly used temporary restorative materials and
through the entire root canal system obturated with
the lateral condensation technique was conducted.
The average time observed for contamination of access cavities sealed with gutta-percha was 7.85 days,
with IRM 12.95 days and with Cavit-G 9.80 days, indicating that even over short periods of time normally
permitted between visits, complete leakage may result. IRM, a common temporary material, was shown

[11] =>

clinical_ leakage prevention

The importance of an immediate definitive
coronal seal should be emphasized
following obturation of the canal system.
to leak to a significantly higher degree than glass
ionomers.33,34 Glass ionomers, due to their adhesive
nature, have demonstrated an ability to prevent bacterial penetration to the periapical of obturated teeth
for over a one-month period as compared to IRM or
Cavit temporary restorations.35
Regarding the temporary restoration’s ability to
prevent coronal leakage, another important consideration is how the material behaves under functional
loading and thermocycling.36 Non-adhesive temporary materials following thermocycling and loading
present with a greater degree of marginal breakdown
and increased microleakage. No significant improvement was reported with increased thickness of the
temporary material.37-39 When teeth were sealed
with IRM, recontamination was detected within 13.5
days in the canals medicated with chlorhexidine,
after 17.2 days in the group medicated with CaOH2
and after 11.9 days in the group medicated with
both chlorhexidine and CaOH2. The group with no
intracanal medication placed and sealed with IRM
demonstrated recontamination after 8.7 days. Statistically significant differences between the teeth
with or without coronal seal were observed. A coronal
seal delayed but did not prevent leakage of microorganisms.40 This has been confirmed in other studies
that IRM started to leak after 10 days, whereas Cavit
and Dyract leaked after two weeks.41,42
Resin-based temporary restorative material or
glass ionomer placed over partially removed resin
composite restorations could be beneficial in achieving better resistance to marginal leakage (Fig. 4).
Maintaining partially removed permanent restorations does not seem to cause a problem with achieving marginal seal.43 Glass ionomers demonstrated a
statistically better coronal seal than bonded compos-

Fig. 7

ite or even a bonded amalgam in preventing bacterial
apical migration.44 This appears to be related to the
glass ionomers’ ability to adhere to sclerotic dentin
found on the pulpal floor better then adhesive resins.45 The key to periapical healing following completion of endodontic treatment seems to be locking out
coronal bacteria so the apical area will heal (Figs. 5, 6).
Mineral trioxide aggregate (MTA) has since its
introduction been advocated as a sealing material,
especially when perforation has occurred. Yet mild
inflammation was observed in 17 and 39 percent of
the roots with and without an orifice plug, respectively, without development of severe inflammation.
The sealing efficacy of MTA orifice plugs could not be
determined as a result.46,47
Should amalgam be the material of choice for the
dentist, a bonded amalgam produced significantly
less leakage than did the non-bonded amalgams. To
prevent the reinfection of the endodontically treated
molar, it may be preferable to restore the tooth immediately after obturation by employing a bonded
amalgam coronal-radicular technique.48 Whereas
good long-term leakage resistance with a core
buildup or access closure with adhesive materials has
been shown, a GI base with overlaying composite (referred to as the “sandwich” technique) or a composite
resin restoration allowed significantly less coronal
leakage than glass ionomer cement restorations. The
composite resin prevents salivary dissolution of the
glass ionomer in the long term.49
Reported results indicate that the sealing ability
of adhesive and flowable materials can decrease
coronal leakage potential.50 Because of the risk of
coronal microleakage, endodontically treated teeth
should be restored as quickly as possible.51 It is more
prudent to use a permanent restorative material

Fig. 7_The pulp chamber has been
etched and an adhesive applied to all
surfaces.
Fig. 8_To assist in locating the
orifices later, a contrasting color light
cure resin is applied over each orifice
and cured.
Fig. 9_The entire pulpal floor is
covered by a flowable composite
and cured.

Fig. 8

Fig. 9

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No matter how well we seal the canal system, if the
coronal portion of the tooth is not thoroughly sealed
then bacterial leakage may just be a matter of time.
for provisional restorations to prevent potential
for coronal leakage and the resulting risk of bacterial penetration through the canal system between
endodontic treatment appoointments.52 To minimize
the potential of perforation when re-entering the
tooth to place either a post at a subsequent appointment or for endodontic retreatment should that be
necessary at a later date, placement of a contrasting
colored resin over each orifice may be beneficial. This
is followed by covering the entire pulpal floor with
a tooth-colored flowable resin (Figs. 7-9). These are
available in a multitude of easily identifiable colored
flowable composites. They are available in pink
(PermaFlo Pink) or purple (PermaFlo Purple) from
Ultradent (South Jordan, Utah) or dark blue from
DenMat (Santa Maria, Calif.).
Coronal microleakage has received considerable
attention as a factor related to failure of endodontic
treatment, and much emphasis is placed on the
quality of the final restoration. Intracanal posts are
frequently used for the retention of coronal restorations.
Many authors have examined coronal microleakage with respect to gutta-percha root fillings and
coronal restorations, but few have investigated the
coronal seal afforded by various post systems. The
seal provided by a cemented post depends on the
seal of the cement used. It appears that the dentinebonding cements (adhesive resins and glass ionomers) have less microleakage than the traditional,
non-dentine-bonding cements (i.e. zinc phosphates
and polycarboxolates).53
Resin fiber and glass fiber posts showed lower
coronal leakage when compared with metal (stainless steel or titanium) and zirconia posts. This may
be related to superior adhesion of the luting agent
to these resin impregnated posts than to metal or
ceramic posts that do not allow adhesive penetration
to the surface of the post.
There were no significant differences between
resin fiber and glass fiber posts at any time period. The
initial leakage measurement in zirconia and metal
posts were similar but became significantly different
at three and six months. Those resin fiber and glass
fiber posts tested exhibited less microleakage compared to zirconia post systems.54

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_Cleansing the canal (smear layer
removal)
Coronal sealing ability is only one factor influencing seal of the canal system and prevention of apical
leakage. Sealer adherence to the canal walls is also an
important factor. The smear layer may play a factor
preventing sealer penetration into the dentinal tubules. The frequency of bacterial penetration through
teeth obturated with an intact smear layer (70 percent) was significantly greater than those teeth that
the smear layer had been removed (30 percent).
Thus, as evidenced by increased resistance to
bacterial penetration, smear layer removal enhanced
sealability.55 In the absence of the smear layer, adaptation of the obturation material was improved
and the incidence of apical leakage was reduced no
matter which obturation method was utilized.56-58
However, regardless of the obturation technique
(single cone, lateral, vertical condensation or thermoplastized) when a non-adhesive sealer was used,
leakage increased after 30 days.59
What material is used for obturation of the canals
is important, however the manner in which the canal
was prepared prior to obturation also determines
how well the canal is sealed when treatment is
completed. Rotary instrumentation with NiTi files
has demonstrated less microleakage than canals
prepared with hand instruments irrespective of what
was used to obturate the canals.60 The better the canal
walls are prepared, the more smear layer and organic
debris are removed, which is beneficial to root canal
sealing. Canal walls instrumented with rotary NiTi
files provide a smoother canal wall and instrumented
shapes that are easier to obturate than are achievable
with hand files. The better adaptation of the obturation material to the instrumented dentinal walls
results in less leakage along the entire canal length.
Smear layer removal is best achieved by irrigating
the canals with NaOCL (sodium hypochlorite) followed by 17 percent EDTA solution.61,62 The NaOCL
dissolves the organic component of the smear layer,
exposing the dentinal tubules lining the canal walls
to which the EDTA, a chelating agent, dissolves the
inorganic portion of the dentin, opening the dentinal
tubules. Alternating between the two irrigants as in-

[13] =>

clinical_ leakage prevention

Fig. 10

strumentation is being performed permits removal of
more organic debris further into the tubules, allowing
sealer to penetrate further into the canal walls and
increasing resistance to bacterial penetration once
the canal is obturated.63-65

_Obturation
The obturation phase of endodontic treatment
has a two-fold purpose: to prevent microorganisms
from re-entering the canal system, and to isolate any
microorganisms that may remain within the canal
system from nutrients in oral fluids. But no matter
how well we seal the canal system, if the coronal
portion of the tooth is not thoroughly sealed then
bacterial leakage may just be a matter of time.
Additionally, accessory canals maybe present
in the pulp chamber, leading to the furcation area,
which may be an additional source of leakage that
often goes unaddressed either following obturation
of the canal system or during the restorative phase.
Sealing this area by placement of a layer of resinmodified glass ionomer cement or an adhesive resin
immediately following obturation can prevent leakage prior to final restoration of the tooth.66
But success can only be achieved if the root
canal system has been as thoroughly debrided as
possible of pulpal tissue and its associated bacteria
lining the canal system walls (the smear layer). Irrigation is key to removal of this smear layer lining
the canal walls.
The obturation material is a two-pronged sword.
Which sealer is used is as important as which core
material is placed within the canal. Gutta-percha
has limitations in resistance to coronal leakage that
have been overcome with newer resin alternatives.
Although sealers can form close adhesion to the root
canal wall, none is able to bond to the gutta-percha
core material. Upon setting, shrinkage of the sealer
allows the sealer to pull away from the gutta-percha

Fig. 11

core, leaving a microgap through which bacteria
may pass.67
Several alternatives are available for core material selection. Gutta-percha demonstrates leakage in
80 percent of specimens related to coronal leakage
when adequate coronal sealing was not achieved,
which is not dependent on obturation technique nor
which sealer was used.68 Because of these limitations seen with gutta-percha, the seal of a coronal
restoration may be as important as the gutta-percha
fill in preventing reinfection of the root canal.69 The
significance of this is, should the coronal break down,
the adhesive obturation material may slow down or
prevent apical migration of bacteria, allowing healing to occur (Figs. 10, 11).
Sealer selection permitting a bond to the core
material is also very important in the prevention of
microleakage. Zinc oxide and eugenol (ZOE) sealers
have been a mainstay in endodontic therapy for
more than 100 years. Yet when exposed to coronal
leakage, ZOE sealers demonstrated complete leakage
by the second day. Results indicated that none of the
ZOE formulations tested could predictably produce a
fluid-tight seal even up to the fourth day.70
AH-26, an epoxy sealer originally introduced
more than 40 years ago, is also unable to bond to
gutta-percha, leading to coronal leakage issues.
Leakage with AH-26 was not dependent on obturation technique, showing gross leakage increasing
within the first four months following obturation
when coronally challenged. Coronal leakage was
significantly greater during the first four months.71
Complete bacterial leakage with AH-26 may be seen
in as few as 8.5 weeks should the coronal restoration
permit leakage.72 Additionally, in-vitro studies found
gutta-percha and AH-26 or AH-26 plus permitted
leakage of both bacteria and fungi.
Leakage in experimental teeth occurred between
14 and 87 days, with 47 percent of the samples
showing leakage, with AH26 sealer permitted bac-

Fig. 10_Periapical lesions associated
with lower premolar and molar
that are obturated with a resin at
completion of endodontic treatment.
(Courtesy of Dr. Joseph Maggio)
Fig. 11_Seven months post
completion of endodontic treatment,
showing loss of coronal restorations,
yet apical lesions seen previously
have resolved significantly due to the
coronal leakage prevention afforded
by the resin obturation. (Courtesy of
Dr. Joseph Maggio)

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[14] =>

I clinical_ leakage prevention

Fig. 12

Fig. 13

Fig. 12_SEM demonstrating
microgap formation with AH-26
epoxy sealer due to polymerization
shrinkage (ES – epoxy sealer;
D – dentin).
Fig. 13_SEM demonstrating intimate
contact with methacrylic sealer and
dentinal tubule penetration of the
sealer (RS – methacrylic sealer;
D – dentin).

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terial leakage in 45 percent and fungi leakage in 60
percent of the samples. AH-26 plus samples demonstrated bacterial leakage in 50 percent and fungi in
55 percent of the samples. There was no statistically
significant difference in penetration of bacteria and
fungi between the two versions of the sealer.73 As
AH-26 is unable to bond to gutta-percha, polymerization shrinkage of the epoxy resin can result in
a microgap leading to the leakage as reported in the
literature (Fig. 12).
The goal is creation of a monoblock with no
interspersed gaps between the canal wall, guttapercha (or alternative cone material) and sealer
(Fig. 13). Should the practitioner wish to continue
using these materials, a permanent restoration
needs to be placed at the appointment when endodontic therapy is completed.
Traditional sealers that have been in use in endodontics for many decades exhibit some cytotoxicity,
especially if any extrudes apically during the obturation phase of treatment.74 These include calcium
hydroxide (CaOH) and zinc oxide eugenol (ZOE) based
sealers. An additional problem with these type sealers
is when coronal leakage occurs the sealer is prone to
dissolution, increasing leakage and the potential for
endodontic failure. This has led to research to find
alternative sealers with better properties that can
resist coronal leakage and are more biocompatible.
Bioceramic sealers have been used increasingly
in endodontics over the past 10 years, and these
materials are calcium silicate in chemistry. Studies
have evaluated their physical properties, biocompatibility, sealing ability, adhesion, solubility and
antibacterial efficacy.75 These materials have been
used in orthopedics for several decades, and biocompatibility has been verified with the material being
non-host reactive following placement.76 Their use
as a replacement sealer in endodontic treatment was
an extension of the success observed in orthopedics

and its biocompatibility and ability to resist dissolution when challenged with fluids.77,78
Antimicrobial effects have been reported for various bioceramic sealers currently available for clinical
use.79,80 When bioceramic sealers are compared to
epoxy resin sealers (AH-26), those calcium silicate
sealers exerted higher antimicrobial effects against
E. faecalis biofilms for longer periods of time.81 These
bioceramic sealers are provided as either ready-touse sealers consisting of only one component (does
not require mixing), with a need for external water
supply from fluid in the canal system when obturation occurs, or two component sealers with internal
water supply that is mixed prior to use.
Both of these material types have the similar setting reactions, whereby a hydration reaction of the
calcium silicate is followed by a precipitation reaction of calcium phosphate.82 The result upon setting
is a relatively insoluble sealer that can resist coronal
leakage, thereby preventing reinfection of the canal
system from salivary bacteria. Their biocompatibility
also is a factor should any sealer be extruded apically
and less irritation is noted compared to ZOE and
CaOH based sealers under similar circumstances.

_Conclusion
The literature suggests that of 41 articles published between 1969 and 1999 (the majority from
the 1990s), the prognosis of endodontically treated
teeth can be improved by sealing the canal system
and minimizing corornal leakage of oral fluids and
bacteria into the periradicular areas as soon as possible after the completion of root canal therapy.83
Endodontic success is multifactorial, with the
full picture, like a jigsaw puzzle, only seen when all
the pieces fit together. How the canals are instrumented and irrigated is as important as what is used
to obturate the canal system. This is also influenced

[15] =>

clinical_ leakage prevention

by what is placed coronally and when the coronal
aspect is sealed. NiTi rotary instruments and an irrigation protocol that includes NaOCL and EDTA will
maximize the sealing ability of glass ionomer or the
newer methacrylic resin sealers.
The last piece of the puzzle, sealing coronally,
should be performed with adhesive permanent restorative materials immediately at the conclusion of
endodontic treatment to prevent apical migration of
bacteria and assure sealability of the canals._

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_about the author

roots

Gregori M. Kurtzman is in
private general dental practice in Silver Spring, Md.,
and a former assistant clinical professor at University of
Maryland in the department
of Restorative Dentistry and
Endodontics and a former
AAID Implant Maxi-Course
assistant program director at
Howard University College
of Dentistry. He has lectured
internationally on the topics of restorative dentistry, endodontics and implant surgery and prosthetics, removable and
fixed prosthetics and periodontics. He has published more
than 750 articles globally, as well as several e-books and
textbook chapters. He has earned fellowship in the Academy
of General Dentistry (AGD), the American College of Dentists
(ACD), the International Congress of Oral Implantology
(ICOI), Pierre Fauchard, ADI, mastership in the AGD and
ICOI and diplomat status in the ICOI, American Dental
Implant Association (ADIA) and the International Dental
Implant Association (IDIA). A consultant and evaluator for
multiple dental companies. Kurtzman has been honored to
be included in the “Top Leaders in Continuing Education”
by Dentistry Today annually since 2006 and was featured on
the June 2012 cover of Dentistry Today. He can be reached
at dr_kurtzman@maryland-implants.com.

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[18] =>

I technology_ laser irrigation

Root canal irrigation
using a laser
Author_Valerie Kanter, DMD

Photos/Provided by Fotona

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1_ 2021

_There are more than 15 million root canal procedures being performed each year. And for years,
dental practitioners have used traditional methods
to treat them. But today, research studies are showing that root canal irrigation is more effective and
patient-friendly when treated with a laser.
With traditional methods, oral infections can
happen because microorganisms have not been
eliminated from the root canal systems, allowing for
recontamination to occur after treatment. In severe
cases, studies have shown that oral infections could
also affect a patient’s cardiovascular health. It is for
this reason that many dental practitioners are upgrading their practices to include a laser.
In my practice, I use the Fotona LightWalker and
Fotona’s newest endodontic laser, the SkyPulse®.
Having the SkyPulse laser allows me to offer technology that preserves the integrity of my patients’
teeth, improves healing times and increases precision
during treatment.
I added the SkyPulse to my arsenal of treatment
tools because it can produce exceptionally low-

energy and short-duration laser pulses optimized to
generate a clinically effective photoacoustic effect
for endodontic treatment using a method called
SWEEPS® (Shock Wave Enhanced Emission Photoacoustic Streaming). It is equipped with a 2940nm
Er:YAG and offers two additional high-performance
diode module accessories to provide a wide range of
both soft- and hard-tissue treatment options. In addition to endodontic applications, it has proven success in periodontics, implantology and soft-tissue
surgery applications.
For me, having SWEEPS is essential to my patient
root canal treatment plan. SWEEPS is a revolutionary
method for chemically cleaning and debriding the
complex root canal system using Er:YAG laser energy
at sub-ablative power levels for a more thorough and
precise irrigation. The minimally invasive instrumentation preserves more of the natural tooth structure
and thereby improves strength and integrity. Using
synchronized pairs of ultra-short pulses, an accelerated collapse of laser-induced bubbles is achieved,
leading to enhanced shock wave emission inside even

[19] =>

technology_ laser irrigation

What do you want
in your practice that
benefits a patient’s
comfort and
decreases pain?
the narrowest root canals. The precise waves of energy
thoroughly clean the complex root canal system that
traditional methods can sometimes miss. The containment of the shockwaves thoroughly streams these
solutions through the entire canal system, enhancing
their effectiveness. The canals and subcanals are left
clean and the dentinal tubules are free of smear layer.
The effectiveness of SWEEPS shouldn’t be underestimated, as it is not uncommon for me to be able to save
a patient’s tooth, even when it was deemed to be a loss
with traditional treatment methods.
SWEEPS is equally effective for final water rinsing
prior to obturation. After sealing the canal, the restoration can be completed finishing off with 1064nm
laser photobiomodulation. What do you want in
your practice that benefits a patient’s comfort and
decreases pain? In my practice and for my patients,
it’s photobiomodulation. Having the 1064nm wavelength there to help stimulate healing after my procedures is profoundly different than anything that I
have experienced in dentistry. It helps ensure that my
patients are comfortable when they leave the office
after a treatment.
This laser treatment is far more advanced than
traditional irrigation procedure methods because the

shockwaves generate cleaning solutions that travel
throughout the entire root canal system, disrupt
biofilms and eliminate bacteria that would otherwise
be left behind to continue to pose a risk on the health
of the tooth and patient as a whole. The powerful
combination of Fotona’s SkyPulse Endo laser and
its SWEEPS treatment represents a unique and
highly effective solution for modern endodontics,
improving irrigation and disinfection. This method
represents an entirely new way of thinking about root
canal therapy with patients receiving fast, safe and
effective root canal treatments._

_about the author

roots

Valerie Kanter, DMD, is a
board-certified endodontist
with a passion for providing
safe and effective biological treatments that relieve
pain, preserve and regenerate natural teeth whenever
possible, and improve the
health and well-being of her
patients.

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[20] =>

I associations_ Foundation for Endodontics

Access to care program
is launched
Author_ Foundation for Endodontics staff

A new program will aid
endodontists in providing free
access to care to underserved
patients (Photo/Provided by
Dreamstime.com)

20 I roots
1_ 2021

_The Foundation for Endodontics, the philanthropic arm of the American Association of Endodontists, and U.S. Endo Partners are launching the
Foundation for Endodontics’ & U.S. Endo Partners’
Domestic Access to Care Program.
The new program will aid endodontic specialists in
providing free access to important endodontic care
to underserved patients within the United States,
according to a press release. In addition to providing
a high level of care to communities that otherwise
might never have the option, the foundation believes
this program’s work will ignite the spirit of philanthropy among endodontists across the nation while
increasing public awareness of endodontics. Ultimately, the foundation looks forward to improving
the overall health and quality of life of the patients
who will receive this care, the press release said.
Access to care was added to the Foundation for
Endodontics’ mission in 2016 to support its work
to save natural teeth for all through the efforts of
endodontic specialists. Three full years after establishing an international program, the
foundation is pleased to announce
an opportunity for endodontists to
positively impact their communities
domestically.
The new funding opportunity’s
application is available this month.
AAE members who are endodontists
are eligible to apply for funding to be
used to support access to free endodontic care. Applicants who submit
a proposal detailing a well-designed
project plan inclusive of how and
where it will serve their community
will be reviewed for funding. It is the
foundation’s hope that these local
initiatives will improve communities and spread the philanthropic
spirit that the foundation embraces
in its work.
The foundation is delighted to
have the support of U.S. Endo

Partners, a management services group that partners
with top tier endodontists throughout the United
States to collaborate and grow their practices, the
press release said. U.S. Endo Partners is generously
supporting the new Domestic Access to Care Program in full with a monetary commitment from 2021
to 2025.
“Since day one of starting our company, elevating patient care and the specialty of endodontics
have been our top priorities,” said Dr. Kirk A. Coury,
founding partner of U.S. Endo Partners and past
treasurer of the Foundation for Endodontics. “Giving our support to this initiative was a very easy
choice to make. By partnering with the Foundation
for Endodontics, we are providing everyone in our
country, particularly the underserved, the opportunity to save their teeth and experience just how lifechanging that can be. Everyone wins: Our specialty,
endodontists, but most importantly, our patients.”
As an expansion of its mission-focused work, the
foundation is honored to offer this new opportunity
for highly trained endodontic specialists to serve
communities in need, the press release said. Not
only is root canal treatment safe and effective, but it
can also lead to better overall health. There are also
countless practical reasons why saving the natural
tooth is a wise choice. Endodontic treatment helps
patients maintain their natural smile, continue
eating the foods they love and limits the need for
ongoing dental work. With proper care, most teeth
that have had root canal treatment can last a lifetime.
“The new AAE program will be a game changer,”
said Dr. Juheon Seung, chair of the foundation’s
Special Committee on Outreach. “With this funding
we will be able to bring highest level of specialist level
care to underserved communities, which wouldn’t
have happened otherwise. There are a lot of great
socially conscious endodontists who want to help
with our specialized skills, but who haven’t had the
resources to make a difference on a scale that will
have significant impact.”
Visit aae.org/foundation/AccessUSA to learn
more about this program or to apply._

[21] =>

meetings_ AAE21

AAE21 goes ‘live &
on-demand’
Author_American Association of Endodontists staff

_AAE21, the annual meeting of the American Association of Endodontists, took place April 21 to 24.
The event was conducted completely online using a
virtual platform allowing attendees to view general
sessions, enjoy live and on-demand educational
content, participate in small-group video chats and
interact with exhibitors.
Known as the premier source of continuing education in endodontics, AAE’s annual meeting is the
largest and most diverse opportunity for learning
the latest endodontic techniques, exploring new
research and exchanging ideas. As the specialty continues to adapt to these changing times, the annual
meeting remains a fixture in advancing the specialty.
Access to the meeting is at www.aae.org/AAE21.
All session recordings are being made available
through the website until May 31, 2021. Virtual attendees may log in and watch sessions as many times
as desired.
Meeting attendees also have access to the AAE’s
virtual exhibit hall, featuring resources and special
offers. The exhibit hall includes a listing of companies,
a showcase of products, show specials and opportunities for industry education.
The Opening General Session featured singersongwriter John Ondrasik as keynote speaker. Ondrasik has spent the past decade writing deeply
personal songs that include social messages, invoke
the human spirit and make an emotional connection. With the past six albums by Five For Fighting,
the hockey moniker stage name under which he
performs, Ondrasik has seen multitudes of successes.
Among the many educational highlights, Dr. Yoshi
Terauchi presented his session, “Do You Know Instrument Retrieval Is Much Easier and More Predictable
Than You Think It Is?” Terauchi offered his expertise
to help participants discover the best techniques for
instrument retrieval.
Other educational highlights included the following:
• “A Potpourri of Pain” — This session, presented
by Dr. Nikita Ruparel and Dr. Ken M. Hargreaves and

moderated by Dr. Jennifer
Gibbs, provided an overview
of pain mechanisms from
the perspective of making
biologically based recommendations for diagnosis
and management of odontogenic and non-odontogenic pain patients.
• “Emerging Techniques
in Endodontic Microsurgery”
— In a session conducted
by Dr. Syngcuk Kim and Dr.
Jarom J. Ray and moderated by Dr. Renato M. Silva,
the bone window technique
and targeted endodontic
microsurgery (TEMS), two
relatively new expansions of
traditional surgical concepts, were presented.
• “To Treat or Not to Treat: Challenging Current
Concepts” — In this session, presented by Dr. Hagay
Shemesh and moderated by Dr. Allen Ali Nasseh, different options for dealing with teeth presenting with
asymptomatic apical periodontitis were discussed,
including avoidance of treatment, monitoring protocols, partial retreatments and alternative solutions.
There were also a number of corporate-sponsored
presentations and various alumni receptions.
The camaraderie continued with “AAE21 Trivia
Night With Two Bit Circus,” which tested participants’
knowledge of the AAE, entertainment, music, sports,
science, pop culture and more.
During the entire meeting, attendees could pick
and choose what live sessions to attend, and they
received access to other sessions at a later date. At the
conclusion of each live presentation, a recording of
the live stream broadcast was made available.
“The AAE’s annual meeting is your No. 1 chance
to grow your expertise, discover innovative products
and services, and network with colleagues from all
over the world,” meeting organizers said._

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[22] =>

I milestones_ John J. Stropko, DDS

Dr. John J. Stropko
retires
Author_Vista Apex staff

Dr. John J. Stropko at his residence
in Arizona. He is retiring after an
extensive career. (Photo/Provided
by Dr. John J. Stropko)

22 I roots
1_ 2021

_After six decades in dentistry, John J. Stropko,
DDS, a microendodontist and inventor, has retired.
He has handed the manufacturing and sale of the
Stropko Irrigator to Vista Apex.
Dr. Stropko had an extensive career. After receiving his DDS from Indiana University in 1964, he

served as a captain in the Air Force Dental Corp until
1966. For the next 24 years, he had a private practice
limited to adult restorative dentistry. In 1987, he was
accepted into the post-graduate endodontic program to study under Dr. Herbert Schilder at Boston
University and received his Endodontic Specialty
Certificate in 1989.
Dr. Stropko had many achievements in his career. In 1995, as an adjunct assistant professor, he
was responsible for starting the micro-endodontic
program at Boston University. He contributed to
textbooks and published an extensive clinical morphology study in the Journal of Endodontics in June
1998. He is also a well-known lecturer with numerous
presentations and live micro-surgical demonstrations given worldwide.
Dr. Stropko is currently the program administrator for the Horizon Dental Institute in Scottsdale, Ariz.
He and his wife, Barbara, reside in Prescott, Ariz.
“Dr. Stropko has made enormous strides in the
advancement of micro-endodontics. His knowledge, commitment and engagement made a profound difference that will have a lasting impact.
We’re honored to have the opportunity to carry
on his legacy,” said Scott Lamerand, CEO of Vista
Apex. “The Stropko Irrigator is in capable hands at
Vista Apex. Vista Apex manufactures and distributes
many products designed to provide safe, efficient
delivery of solutions. Stropko Irrigator helps us
further that passion.”
Lamerand added, “Dr. John Stropko exudes passion for dentistry. His career is evidence of that. I
think that I can speak for most that we are thankful
for Dr. Stropko’s contributions to the dental industry
and wish him and his family the very best following
his retirement. That said, I expect to speak with him
regularly to be sure we continue doing things the
right way.”
In April, Dr. Stropko became editor in chief of roots
magazine._

[23] =>

about the publisher _ imprint

roots

the international C.E. magazine of endodontics

U.S. Headquarters
Tribune America
118-35 Queens Blvd, Ste 400
Forest Hills, NY 11375
Tel.: (212) 244-7181
Fax: (212) 244-7185
feedback@dental-tribune.com
www.dental-tribune.com

Group Editor
Kristine Colker
k.colker@dental-tribune.com

Product/Account Manager
Humberto Estrada
h.estrada@dental-tribune.com

Roots Managing Editor
Fred Michmershuizen
f.michmershuizen
@dental-tribune.com

Product/Account Manager
Maria Kaiser
m.kaiser@dental-tribune.com

Publisher
Torsten R. Oemus
t.oemus@dental-tribune.com

Client Relations Coordinator
Leerol Colquhoun
l.colquhoun@dental-tribune.com

President/
Chief Executive Officer
Eric Seid
e.seid@dental-tribune.com

Accounting Coordinator
Nirmala Singh
n.singh@dental-tribune.com

Feedback & General Inquiries
feedback@dental-tribune.com

Editorial Board

Marcia Martins Marques, Leonardo
Silberman, Emina Ibrahimi, Igor Cernavin,
Daniel Heysselaer, Roeland de Moor, Julia
Kamenova, T. Dostalova, Christliebe Pasini,
Peter Steen Hansen, Aisha Sultan, Ahmed
A Hassan, Marita Luomanen, Patrick Maher,
Marie France Bertrand, Frederic Gaultier,
Antonis Kallis, Dimitris Strakas, Kenneth Luk,
Mukul Jain, Reza Fekrazad, Sharonit
Sahar-Helft, Lajos Gaspar, Paolo Vescovi,
Marina Vitale, Carlo Fornaini, Kenji Yoshida,
Hideaki Suda, Ki-Suk Kim, Liang Ling Seow,
Shaymant Singh Makhan, Enrique Trevino,
Ahmed Kabir, Blanca de Grande, José Correia
de Campos, Carmen Todea, Saleh Ghabban
Stephen Hsu, Antoni Espana Tost, Josep
Arnabat, Ahmed Abdullah, Boris Gaspirc,
Peter Fahlstedt, Claes Larsson, Michel Vock,
Hsin-Cheng Liu, Sajee Sattayut, Ferda Tasar,
Sevil Gurgan, Cem Sener, Christopher Mercer,
Valentin Preve, Ali Obeidi, Anna-Maria
Yannikou, Suchetan Pradhan, Ryan Seto, Joyce
Fong, Ingmar Ingenegeren, Peter Kleemann,
Iris Brader, Masoud Mojahedi, Gerd Volland,
Gabriele Schindler, Ralf Borchers, Stefan
Grümer, Joachim Schiffer, Detlef Klotz,
Herbert Deppe, Friedrich Lampert, Jörg
Meister, Rene Franzen, Andreas Braun, Sabine
Sennhenn-Kirchner, Siegfried Jänicke, Olaf
Oberhofer and Thorsten Kleinert

Tribune America is the official media partner of:

roots_Copyright Regulations
_the international C.E. magazine of roots published by Tribune America is printed quarterly. The magazine’s articles and illustrations are
protected by copyright. Reprints of any kind, including digital mediums, without the prior consent of the publisher are inadmissible and liable
to prosecution. This also applies to duplicate copies, translations, microfilms and storage and processing in electronic systems. Reproductions,
including excerpts, may only be made with the permission of the publisher.
All submissions to the editorial department are understood to be the original work of the author, meaning that he or she is the sole copyright
holder and no other individual(s) or publisher(s) holds the copyright to the material. The editorial department reserves the right to review all
editorial submissions for factual errors and to make amendments if necessary.
Tribune America does not accept the submission of unsolicited books and manuscripts in printed or electronic form and such items will
be disposed of unread should they be received.
Tribune America strives to maintain the utmost accuracy in its clinical articles. If you find a factual error or content that requires clarification, please contact Group Editor Kristine Colker at k.colker@dental-tribune.com. Opinions expressed by authors are their own and may
not reflect those of Tribune America and its employees.
Tribune America cannot assume responsibility for the validity of product claims or for typographical errors. The publisher also does not
assume responsibility for product names or statements made by advertisers.
The responsibility for advertisements and other specially labeled items shall not be borne by the editorial department. Likewise, no responsibility shall be assumed for information published about associations, companies and commercial markets. All cases of consequential liability
arising from inaccurate or faulty representation are excluded. General terms and conditions apply, and the legal venue is New York, New York.

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_ 2021

[24] =>

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[cover] => roots C.E. No. 1, 2021

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Table of contents

[toc_titles] =>

Cover / Contents / Editorial / Coronal leakage prevention to improve endo success / Root canal irrigation using a laser / AAE21 goes ‘live & on-demand’ / Dr. John J. Stropko retires / Imprint

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