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Journal of Oral Science, Vol. 52, No. 2, 325-328, 2010
Case Report
Single-session use of mineral trioxide aggregate as an apical
barrier in a case of external root resorption
Roberta A. Araújo1), Cláudia F. M. Silveira1), Rodrigo S. Cunha2),
Alexandre S. De Martin1), Carlos E. Fontana1) and Carlos E. S. Bueno1,2)
1)Department
of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, Brazil
of Endodontics, Catholic University of Campinas, Campinas, Brazil
2)Department
(Received 27 July 2009 and accepted 19 February 2010)
Abstract: External root resorption may occur as a
consequence of trauma, orthodontic treatment, bacterial
infection or incomplete sealing of the root canal system
(bacterial re-infection), and lead to crater formation
on the resorbed apex. This would deform the root apex
surface, and cause loss of apical constriction. Depending
on the extent of the resorptive process, different
treatment regimens have been proposed. A 34-year-old
male patient presented with an intra-radicular retainer
and an inadequate filling on tooth #21, as well as a
radiographic image suggesting periapical bone
rarefaction. After root canal retreatment, the defect was
accessed coronally. The resorption area was chemomechanically debrided and since the apical end was very
wide, a calcium sulphate matrix was made. Mineral
trioxide aggregate (MTA) was used to fill the resorptive
defect, and the coronal access was temporarily sealed.
After 24 h, the quality of the apical seal was evaluated
with the aid of an operating microscope, and then the
root canal system was filled. A 12-month follow-up
radiograph showed adequate repair of the resorption.
Clinically, the tooth was asymptomatic. We concluded
that MTA can be successfully used to avoid
overextension of the filling material when treating a
tooth with external resorption. (J Oral Sci 52, 325328, 2010)
Correspondence to Dr. Roberta Aranha de Araújo, Av. Eng.
Luís Gomes Cardim Sangirardi, 360, apto. 91, Aclimação, São
Paulo, SP 04112-080, Brazil
Tel: +55-19-3251-5656
Fax: +55-19-3251-5656
E-mail: roberta.aranha@terra.com.br
Keywords: mineral trioxide aggregate; apical plug;
root resorption; endodontics.
Introduction
Root resorption can be classified as internal or external,
depending on the radiographic aspect. Internal resorption
is characterized by resorption of the pre-dentin and root
dentin adjacent to the granulation tissue produced by the
pulp. Although there are several theories regarding the
origin of this pulpal granulation tissue observed in
resorption cases, the most logical explanation is that
inflammation develops in the pulpal tissue due to infection
of the coronal pulp, or as a result of trauma (1).
In the case of external resorption, the root cementum
and dentin are resorbed, and bone resorption follows (1).
There is crater formation on the resorbed apex, deforming
the root apex surface, and consequently, loss of apical
constriction. Trauma, orthodontic treatment (2), bacterial
infection or incomplete sealing of the root canal system
(bacterial re-infection) can lead to this process of apical
resorption.
Due to the wide nature of the apical foramen, MTA may
be inserted in the apical portion of the root to allow the
formation of an artificial barrier in the root apex (3). This
is an alternative treatment (4) that avoids overextension
of the filling material, allows good apical sealing, and
reduces treatment time, thereby avoiding fracture of the
tooth and microleakage between sessions (5). Furthermore,
MTA exhibits good biological properties and stimulates
repair (6).
When used on dog teeth with incomplete root formation
and with contaminated canals, MTA induced the formation
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of an apical barrier of hard tissue (4).
The aim of this article was to describe immediate
endodontic treatment of tooth #21, using an apical barrier
of MTA.
Case Report
Fig. 1 Preoperative diagnostic radiograph.
Fig. 2 Preoperative image showing a wide
apical foramen due to external resorption
(×12.5 magnification).
Fig. 3 Insertion of white MTA-Angelus over the
calcium sulphate matrix as an apical
barrier of approximately 3-mm thickness
(×20 magnification).
The patient, a 34-year-old man, was referred for
endodontic treatment of tooth #21. During clinical and
radiographic examination, the presence of a complete
prosthetic crown, an intra-radicular retainer and faulty
obturation was observed. A radiographic image suggesting
periapical bone rarefaction was also observed (Fig. 1).
Initially, the full crown was removed with the aid of a
tapered trunk carbide bur No. 1557 (KG, Sorensen, São
Paulo, SP, Brazil), at high speed, and an ultrasound insert
5AE (Gnatus, Ribeirão Preto, SP, Brazil). Then, the post
was worn with a tapered trunk bur No. 1557 and, with the
purpose of exposing the cement line close to the root
remnant, in the most cervical portion of the root, a onehalf spherical carbide bur was used. A 5AE ultrasound insert
was again applied to all aspects of the core, thus producing
microfragmentation of the cement and removal of the
post.
Cleansing of the root canal system began with removal
of the obturation material present. Debridement was
performed using the crown-down technique with Flexofile
files (Dentsply/Maillefer, Ballágues, Switzerland) and
2.5% sodium hypochlorite (Fórmula & Ação, Brasil, São
Paulo, SP, Brazil) was used as irrigant solution. The
working length was determined with the aid of an apex
locator (ROOT ZX II, J. Morita, Kyoto, Japan).
Due to the apical deformity resulting from the external
resorption, the apical end was found to be very wide (Fig.
2). Thus, we decided to make a calcium sulphate matrix
as a protection to prevent exaggerated extravasation of the
white Angelus MTA that was inserted over this matrix as
an apical barrier of approximately 3-mm (Figs. 3 and 4).
The MTA was introduced with the aid of a Dovgan 1.6mm MTA holder (Quality Aspirators, Duncanville, TX,
USA) and adapted with a No. 1 vertical condenser in the
apical portion of the canal. This procedure was performed
with the aid of an operating microscope (DF Vasconcelos,
São Paulo, SP, Brazil). Because of the long setting time
of MTA, the tooth was sealed with a paper cone dampened
with Z350 composite resin (3M, Sumaré, SP, Brazil). The
next day, the quality of the apical seal was evaluated with
the aid of an operating microscope and, then the canal was
filled with main non-standardized gutta-percha cones and
AH Plus cement (Dentsply/Maillefer, Ballágues,
Switzerland) using the lateral condensation technique.
The full crown was rebased and used at this stage of
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endodontic re-treatment as a provisional crown. Next, a
new ceramic core and crown were made.
The case was followed-up after 12 months, and there
were no further signs or symptoms (Fig. 5).
Discussion
When periodontal ligament and cementum are
traumatized by, for example, intrusion, luxation, or
exfoliation, external resorption may result. The origin of
this process lies then not within the pulp as with internal
resorption, but rather with the periodontal ligament. The
process inflammation within the injured tissue now directly
contacts the cementum and external resorption can ensue
(3). It is important to consider that external resorption
may not only be a sequela of acute trauma, but, as
Andreasen stated, may also follow injury to the periodontal
ligament which is related to orthodontic, periodontic,
pedodontic, or endodontic procedures. In the apical area,
early necrosis of the pulp tissue or incomplete root
formation and external resorption may each show a blunted
or shortened root with an open foramen. However, these
conditions may be differentiated by the shape and size of
the canal system and the appearance of the apex. With early
pulpal death or incomplete root formation, the canal system
is large with parallel or divergent walls, and the apex may
be blunderbuss-like in appearance. This contrasts with
apical external resorption where the canal size will generally
be smaller, and the walls will converge apically (2).
In the present case, owing to a faulty initial endodontic
treatment, with incomplete sealing of the root canal system,
bacterial re-infection is likely to have occurred, leading
to apical resorption. Endodontic re-treatment was therefore
indicated. As a result of this apical resorption, the tooth
presented a wide apical foramen, with morphologic
deformities, making it difficult to obtain a good apical seal,
as is also the case of teeth with incomplete root formation.
We therefore decided to perform an alternative treatment,
as opposed to the treatment in which successive changes
of calcium hydroxide dressings are placed for several
months (7). Because the foraminal diameter was a concern,
while aiming for a hermetic seal of the canal and avoiding
overextension of the filling material, a 3-mm apical MTA
barrier was made, after a calcium sulphate protection was
placed. This would avoid prolonged treatment, and
consequently, fracturing of the tooth and coronal
microleakage between sessions (7).
Al-Kahtani et al. (8) recommended placement of a 5mm apical barrier of MTA in cases of apexification, as this
allows for an excellent seal, and because sufficient material
thickness is obtained to prevent it from being displaced.
In this same study, they obtained a relative success index
Fig. 4 MTA introduced and adapted to the
apical portion of the canal.
Fig. 5 Radiographic view after 1 year.
of 81% of the cases studied in vivo. The root was not so
narrow and the foramen was not as wide as in the cases
of apexification, and preparation was required to place an
intra-radicular retainer; therefore, a 3-mm apical barrier
was chosen in the present case.
Magnification with an operating microscope enabled
visualizing the entire length of the canal up to the apical
foramen. It also allowed the entire process of inserting the
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MTA as an apical barrier to be perfectly supervised, thus
enabling confirmation that a correct apical seal was achieved
(3).
Although thermo-plasticization techniques have been
commonly used (5), we used the lateral condensation
technique with non-standardized cones because of the
possibility of filling material extravasation.
In addition to avoiding possible tooth fracture (5), the
act of filling the canal and cementing a temporary prosthetic
crown, and then manufacturing the intra-radicular post and
definitive crown immediately afterwards, allows immediate
coronal sealing, which is considered a key factor in
preserving the treatment in the long run (7).
Inserting MTA in the apical portion of the root after canal
preparation favors the establishment of a healthy periodontal
ligament as well as the new formation of bone and
cementum. Due to its favorable histologic response, MTA
has been considered a material that is effective as an apical
barrier in cases of incomplete root formation. Its application
results in predictable apical closing, reduced treatment time
and a reduced number of radiographs taken (7).
We decided not to place calcium hydroxide before the
MTA, in accordance with the study by Holland et al. (9),
in which the authors observed that placing calcium
hydroxide paste for two weeks in a contaminated perforated
area in dog teeth before sealing with MTA, histologically,
brought no benefits to the repair process when compared
to MTA insertion without previously placing the calcium
hydroxide medication.
Follow up of the case is of utmost importance to observe
the success of the treatment. Orstavik (10), from his
research, recommended that follow up should be performed
for a minimum of 1 year. Ghaziani et al. (11) reported the
successful treatment of two maxillary central incisors that
had open apices and periapical lesions using MTA apical
plugs after the root canals had been debrided and rinsed
with 2.5% sodium hypochlorite. Calcium hydroxide paste
was then placed in the canals for 1 week, before the apical
portion of the canals (5 mm) was filled with the MTA plug.
The remaining portion of the root canal was then sealed
with a post and crown. After 6 months of follow-up, the
clinical and radiographic appearance of the teeth showed
resolution of the periapical lesions. At 2 years, although
the left post was lost and the periapical lesion of the left
central incisor had subsequently deteriorated, the right
central incisor had healed successfully. The authors
concluded that use of MTA as an apical plug in necrotized
permanent teeth with open apices is a valuable method if
the quality of coronal sealing can be improved. This would
allow long term apexification to be replaced by apical
plugging with MTA, thus reducing the treatment time.
Based on the results of the present investigation,
placement of an apical barrier using MTA is an alternative
to conventional long-term calcium hydroxide therapy.
Future studies focusing on an improved placement
technique to enhance the sealing ability of MTA as an apical
plug would help to support this treatment modality.
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