Successful Endodontic Treatment Of Internal Cervical Root Resorption



It is well known that long-term success and predictability of
root canal therapy is dependent on the presence, or absence,
of infection and our ability to disinfect and seal all the main
and accessory canals three-dimensionally. Prognosis for
endodontic therapy in teeth with apical periodontitis is 10-
15% lower than for teeth without periapical lesion.1,2 Once the
tooth becomes infected, it becomes very difficult to completely
eliminate the bacteria from the three-dimensional network of
complicated root canal systems.3 Several pigmented endodontic
pathogens, such as P. gingivalis, P. endodontalis, P. intermedia
and P. nigrescens, have been found to persist after proper
instrumentation of the canals, and are responsible for failure of
endodontic therapy.4 Smear layer produced during mechanical
instrumentation, with either rotary or hand files, reduces
permeability of intra-canal irrigants, like NaOCl(sodium
hypochlorite) and CHX(chlorhexidine) by 25-49%.5 Hence,
anti-bacterial rinsing solutions can only reach the bacteria to
a depth of 100mm into the depth of the dentinal tubules.6
However, microorganisms such as E. faecalis have been found
as deep as 800-1100mm.
In the recent years, different laser wavelengths have been
shown to be advantageous for deeper penetration of dentinal
tubules, compared with chemical irrigants9,10 and therefore,
for better bactericidal effect.11,12 The Er,Cr:YSGG laser
system has been shown to eradicate E. faecalis and E.Coli to
undetectable levels, with average temperature rise at the root
surface of only 2.7-3.2oC, depending on the power used.13
Complete smear layer removal has been shown by both the
Er,Cr:YSGG 2780nm and the Er:YAG 2940nm laser systems,
due to induction of shock waves in aqueous solutions (water,
EDTA) inside the root canals.14,15 Although EDTA by itself
is effective in smear layer removal in straight large canals, its
effectiveness is improved by laser activation in small curved
The clinical case presented here describes a successful
endodontic treatment of a lower premolar, which exhibited
radiographic signs of internal resorption and a buccal
perforation. This microscope observation by an endodontist
suggested a hopeless prognosis for the tooth and, hence,
the recommended extraction. We utilized a Er,Cr:YSGG
wavelength for removal of organic debris and smear layer,
followed by a diode 940nm wavelength, known for its ability
Successful Endodontic
Treatment Of Internal
Cervical Root Resorption
Using Er,Cr:YSGG 2780nm and
Diode 940nm Laser Systems:
A Three-Year Follow-Up Case Report
Marina Polonsky, DDS, MSc Lasers in Dentistry Keywords: endodontics, root canal, internal
resorption, Er,Cr:YSGG, diode, Laser, irrigation,
to penetrate deep into the tubules and disinfect. In this case,
the use of NaOCl, and likely hypochlorite extravasation into
the periodontal ligament in the area of buccal perforation
had to be avoided.
Case Report
A 52-year-old male presented to the dental office for a
routine prophylaxis appointment, in December 2013, and
was clinically diagnosed with interproximal decay on the
distal surface of lower right second premolar (tooth 45). A
closer radiographic examination revealed an area of internal
resorption in close proximity to the decay (Fig. 1). A composite
resin restoration was completed without pulp exposure,
but close proximity to the area of internal resorption
was explained to the patient. In case of an onset of symptoms
of irreversible pulpitis, the patient was instructed to contact
the office immediately. Two months later, in February 2014,
the patient contacted the office complaining of lingering
cold sensitivity and was referred to the endodontist for
consultation regarding feasibility of root canal therapy. The
endodontist report indicated that buccal perforation was
observed and prognosis was deemed to be hopeless (Fig. 2).
Recommended treatment was extraction of the tooth and
implant placement.
Upon the patient’s return to the office in March 2014 for
possible extraction, the use of lasers in endodontics to help
with extremely compromised cases [18,19] was explained,
and the patient consented to try laser-assisted endodontic
treatment. Inferior alveolar nerve block was administered
using 4% Articaine 1:200,000 Epi. The tooth was accessed
following removal of the temporary filling placed by the
endodontist. Working length was measured to be 20mm.
Mechanical instrumentation of the canal was completed
using Sybron TF adaptive reciprocating motor system
up to file ML2 corresponding to ISO 35 size master file.
FileEze (Ultradent, South Jordan,UT, USA) was used for
file lubricant and BioPure MTAD (Mixture of tetracycline
isomer, citric acid and detergent) by Dentsply Tulsa Dental
Specialties, Tulsa, Okla.,USA was chosen as the intra-canal
irrigation, since the presence of buccal perforation contra-indicated
the use of NaOCl or EDTA. Before final obturation,
dual wavelength laser cleaning and disinfection protocol was
Dual Wavelength Endodontic debridement, decontamination
and disinfection laser protocol:
1. Debridement. 2780nm Er,Cr:YSGG laser (Biolase, IPlus,
Irvine, CA), 60ms pulse (H-mode), RFT2 radial firing
endolase tip 200mm diameter. Power 1.25W, Repetition
rate 50Hz, Pulse energy 25mJ/pulse, 54% water, 34% air.
The tip was measured 1mm short of working length and
fired only on the way out of the canal. The tip was moved
in a corkscrew-like motion at a speed of 1mm/s. Due to
complexity of internal resorption pattern, it was chosen
to repeat for 6 cycles of 15s (instead of recommended 4
cycles). Total time of laser application 90s, total energy
delivered 112.5 Joules. Calibration factor for RFT2 tip is
0.55, so the actual energy delivered to the surface of canal
wall is 62J.
2. Decontamination. 2780nm Er,Cr:YSGG laser, 60ms pulse
(H-mode), RFT2 radial firing endolase tip 200mm
diameter. Power 0.75W, Repetition rate 20Hz, Pulse
energy 37.5mJ/pulse, 0% water, 11% air. The tip was
inserted into the canal 1mm short of the apex and fired
only on the way out of the canal. The tip was moved in a
corkscrew-like motion at a speed of 1mm/sec. 6 cycles of
laser irradiation were applied, 15 seconds each, for a total
Endodontic therapy for teeth diagnosed with irreversible
pulpitis has been in use for many years, and continues to be
the standard of care in the dental practice. In simple cases,
where mechanical instrumentation and chemical irrigation
can achieve sufficient cleaning and disinfection, endodontic
treatment is reported to be as high as 96% successful.
However, in cases where root canal systems are more
complex, proper cleaning of the organic debris, removal of
smear layer and disinfection, has proven to be a challenge.
Long-standing chronic periapical lesions and complex root
canal anatomy, examples of which include the presence of
isthmus, apical deltas and lateral canals, the predictability
of successful endodontic therapy is significantly reduced.
Lasers of different wavelengths have been shown to be
useful in improving disinfection and smear layer removal
in more complicated endodontic cases. In this article, we
describe a case of laser-assisted endodontic therapy of a
lower premolar exhibiting radiographic evidence of internal
cervical resorption and clinical symptoms of irreversible
pulpitis. The case was recommended for extraction following
endodontic consultation, as there was suspected buccal
root perforation. Conventional mechanical instrumentation
was performed, followed by a dual wavelength protocol utilizing
the Er,Cr:YSGG 2780nm laser for smear layer removal
and the diode 940nm laser for deeper disinfection of the
dentinal tubules. Conventional chemical irrigants, such as
NaOCl and EDTA, were not used due to suspected buccal
perforation and the possibility of chemical extrusion outside
the root and into the surrounding tissues. The protocol
was successful and three-year radiographic follow-up is
presented as evidence.
66 oralhealth MAY 2017
of 90s. Total energy delivered 67.5J. Calibration factor
for RFT2 tip is 0.55, so the actual energy delivered to the
surface of canal wall was 37J.
3. Drying. Sterile paper points were used to verify complete
dryness of the canal system, as much as possible with
such complex internal resorption network.
4. Disinfection. 940nm diode laser, continuous wave mode,
EZ200 end-firing tip 200mm diameter. Power 1.0W. Tip
was inserted 1mm short of the apex and moved at the
speed of 2mm/s while being fired on the way out of the
canal. 6 cycles of 7.5s each for a total 30s of irradiation.
Total energy of 30J was delivered.
Following the laser protocol, the canal was filled with
hydrophilic EndoRez UDMA
(urethane dimethacrylate)
resin based, self-priming
endodontic sealer (Ultradent,
South Jordan, UT, USA) to
the level of the CEJ (cementum-enamel
junction). Gutta-Core
#30 (Dentsply, Tulsa
Dental Specialties) softened
gutta percha carrier was used
to complete the obturation.
The tooth was permanently
restored with resin restoration
(FutureBond DC bonding
agent and GrandioSO nanohybrid composite resin by Voco,
Germany) immediately following obturation (Fig. 3). The
patient was instructed to inform the office should any pain
or discomfort persist past first two to three days following
the endodontic therapy. He returned in three months for a
routine follow-up and reported only minor discomfort for
the first two to three days, which quickly subsided, with the
tooth feeling “normal” ever since. Post-op radiographs were
taken at 3, 9, 24 and 36 months after the completion of the
laser-assisted endodontic treatment (Figs. 4-8). The tooth
remains asymptomatic and functional.
The three-year success of this complicated case can be
attributed to a number of clinical decisions: 1. The timely
intervention at the irreversible pulpitis stage and before the
onset of peri-apical infection and bacterial colonization.1,2
2. The effectiveness of the Er,Cr:YSGG laser system in
three-dimensional removal of organic debris and smear layer
from the extensive internal resorption network of canals.13-16
3. The ability of the 940nm diode wavelength to penetrate
deep into the tubular dentin to help dry the internal structure
of resorption network and target
pigmented bacteria, due to its
high absorption in melanin and
hemoglobin.20 4. The hydrophilic
and biocompatible nature
of a UDMA resin sealer like
EndoRez, which is well tolerated
by periapical tissues in case of
overfill or extrusion.21-23
It has been shown that
bacterial contamination of the
root canal system, presence of
necrotic tissue and bacterial
colonies deep inside the dentinal
tubules (as far as 1.1mm)24 are the main contributing factors
to the long-term failure of endodontic therapy. Performing a
root canal treatment prior to onset of deep bacterial colonization
is a valuable service we can provide to our patients, to
ensure long-term success. Unfortunately, early intervention is
not always possible. As well, the difficult three-dimensional
anatomy of the canal systems, such as internal resorption
network, also makes it difficult to achieve complete debride-
on page 69
Pre-op X-ray of internal resorption and
distal decay.
December 2013.
Pre-op photo of internal resorption by
Dr. Thompson. February 2014.
Immediate post-op X-ray.
March 2014.
1. 2. 3.
Cooling effects of
blood circulation should
make this protocol even
safer in vivo
ment and disinfection of the entire surface area of the root
canal walls and into the depth of the tubules. Laser systems,
such as the 2780nm Er,Cr:YSGG and the 940nm diode, add
an advantage to the traditional mechanical debridement and
chemical disinfection. The Er,Cr:YSGG laser is a free-running
pulsed laser with a high absorption in hydroxyapatite
(HA) and water (OH- radical to be more precise). Activation
of aqueous solutions, such as water and EDTA, with this
laser creates cavitation effects and shock waves responsible
for debris and smear layer removal inside the root canal.
Open dentinal tubules then allow laser light conduction and
effective disinfection as far as 500mm deep into the tubules
with this 2780nm laser system alone.25 To achieve an even
greater penetration of laser energy, and accompanying bactericidal
effect, the addition of second wavelength, like the
940nm diode, offers extra benefit. Diode lasers have deeper
penetration in dentin26,27; their high absorption in melanin
and hemoglobin allows for selective killing of pigmented and
pigment producing bacteria, which make up the majority of
endodontic infections.4 A recent study has shown that dual
wavelength protocol (2780nm with 940nm) is safe and does
not result in adverse temperature changes on the external root
canal surface in vitro.28 Temperature rise was recorded to be
5oC to 7oC depending on the thickness of the dentinal wall.
Continuous movement of the laser tip inside the canal and
distilled water irrigation, between laser exposures, ensures
control of temperature rise. The cooling effects of blood circulation
should make this protocol even safer in vivo. Lastly, the
sealer chosen to complete the endodontic obturation is also of
great importance to the long-term success of complicated cases
involving possible perforations and/or open apices. Extrusion
of EndoRez sealer past the apex has been shown to be well
tolerated by periapical tissues and does not interfere with normal
bone healing.22,23 Owing to its hydrophilic nature, good
flow and wetting characteristics21, it is ideal for the filling of
the complex internal resorption network of canals, especially
since complete dryness inside the tooth cannot be accomplished
with the use of paper points, and possibly even diode
laser irradiation. It has even been suggested that EndoRez
increased the fracture resistance of the endodontically treated
roots to internally generated stresses.29
The three-year success of this clinical case may be an indication
that laser systems, such as the Er,Cr:YSGG (IPlus by Biolase)
and 940nm diode (Epic 10 by Biolase), can be beneficial
from page 66
Three-months post-op X-ray.
June 2014.
24 months post-op X-ray
March 2016.
Nine-months post-op X-ray.
December 2014.
36 months post-op X-ray.
April 2017.
15 months post-op X-ray
June 2015.
70 oralhealth MAY 2017
additional tools in the treatment of extremely complicated endodontic
cases, otherwise doomed for extraction. The possible
presence of buccal perforation, in this case of internal cervical
resorption, contra-indicated the use of conventional irrigants,
such as NaOCl and EDTA, due to the likely occurrence of a
painful hypochlorite accident in the periodontal tissues. An inability
of conventional hand or rotary files to completely remove
organic material from such a complex resorption system was
another reason for recommended extraction for this premolar
tooth. The lasers’ ability to remove debris and smear layer with
acoustic shockwaves and the great bactericidal effect30, due to
deep penetration and pigment affinity, helped us treat this case
in a conservative, non-surgical manner and without the use of
potentially harmful chemical irrigants. OH
Oral Health welcomes this original article.
Thank you Dr. Thompson of Capital Endodontics in Ottawa, ON,
Canada for providing pre-op photo of internal resorption.
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Dr. Marina Polonsky DDS, MSc is a
gold medal University of Toronto ’99
graduate, she maintains private general
practice in Ottawa, Ontario with
focus on multi-disciplinary treatment
utilizing lasers of different wavelengths.
She holds a Mastership from
World Clinical Laser Institute (WCLI),
Advanced Proficiency Certification
from Academy of Laser Dentistry
(ALD) and Master of Science in Laser
Dentistry from RWTH University in
Aachen, Germany. Dr. Polonsky is a founder of the Canadian Dental
Laser Institute (CDLI)