Mineral trioksit agregat ve ışıkla sertleşen cam iyonomer simanın devital ağartma işlemlerinde kullanımının değerlendirilmesi

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Introduction
Non-vital bleaching is most commonly applied
to endodontically treated discolored anterior teeth.
Patients refer to dentists just for esthetic purposes,
so clinicians should take care to avoid microleakage
during the bleaching procedures. Microleakage is a
reason of the failure of even a well-treated tooth. It is
important to know that not only a hermetical apical
sealing but also a tight coronal sealing are important
for success. The main complication of intracoronal
bleaching is external root resorption (1). Nutting and
Poe reported that the application of intraorifice barrier is essential to prevent penetration of the liberated oxgen from the bleaching material into the dentin tubules and periodontal tissues, as well as into
the periapical region causing a painful reaction (2).
Additionally, in order to eliminate the incidence of
external root resorptions, Friedman et al. recommended the placement of a protective cervical base (3).
Many other authors also recommended the use of
intraorifice barrier (4-7). Therefore, isolation of rootcanal with an intraorifice barrier is essential to avoid
bacterial recontamination and penetration of bleaching materials into the root-canal during the bleaching procedures (8). A myriad of commonly used
temporary and permanent restorative materials have
been studied as intracoronal barriers. Characteristics
that qualify a restorative material as an ideal intracoronal barrier include ease and speed of placement,
sealing efficacy, and high bond strength (9-12). The
ideal properties of a coronal barrier have been proposed by Wolcott et al. to include the following characteristics: easily placed, bonds to tooth structure, seals
against microleakage, distinguishable from natural
tooth structure (13).
A variety of restorative materials have been used
in attempt to produce a barrier (13,14). One of these materials, mineral trioxide aggregate (MTA) (Tulsa
Dental, Tulsa, OK, USA) has been evaluated for a wide
* Department of Conservative Dentistry and Endodontics, Faculty of
Dentistry, University of Zonguldak Karaelmas, Zonguldak, Turkey
** Department of Dentistry, Turkish Land Forces Command, Infirmary,
Anıttepe, Ankara, Turkey
*** Department of Conservative Dentistry and Endodontics, Faculty of
Dentistry, University of Gazi, Ankara, Turkey
Reprint request: Elif Aybala Oktay, Department of Dentistry, Turkish Land
Forces Command, Infirmary, Anıttepe, Ankara, Turkey
E-mail: eaybala@yahoo.com
Date submitted: January 07, 2010 • Date accepted: April 19, 2010Volume 52 • Issue 2 Glass ionomer cement in coronal bleaching • 97
variety of applications (15). These applications include pulp capping, apical barrier, perforation repair
and root-end filling material. Because of its superior
sealing ability and resistance to microleakage, MTA
has gained attention (16). MTA, composed mainly
of tricalcic silicate, tricalcic alluminate, bismuth oxide, is particular endodontic cement. It is made of
hydrophilic fine particles that harden in the presence
of dampness or blood. It is biocompatible, radiopaque and it is harder to infiltrate, compared to classic
materials such as amalgam, cements, Super-EBA, and
IRM (17). Recently, gray color and white color MTA
have been available in the markets. The only chemical difference between the gray and white MTA is the
reduced iron content in white MTA, and physically
the particul size of white MTA is smaller to enhance
handling and placement characteristics (8).
Vitremer (3M ESPE, St. Paul, USA) light curing glass
ionomer cement was proved to be an effective sealant
to be used in moist environment such as root resections. This material presents no water sensitivity and
has proved its biocompatibility (18). However, there
are only a few studies that evaluate the material as a
coronal barrier material.
The purpose of this study was to evaluate the coronal leakage of intraorifice barriers with different
thicknesses; gray MTA, white MTA and light curing
glass ionomer cement using a dye penetration model.
Material and Methods
One-hundred and thirty extracted, anterior human teeth were used in this study. All teeth were
cleaned free of attached soft tissue and stored in
normal saline solution. The roots were shaped with
ProTaper (Dentsply Maillefer CH-1338 Ballaigues,
Switzerland) to a size 30# and obturated with gutta
percha (Dentsply Tulsa Dental, Tulsa, OK) and AH26
(Dentsply De Trey, Konstanz, Germany) sealer. After
the removal of coronal gutta percha, the teeth were
randomly divided into 6 groups. In group 1, 20 teeth received 2 mm of gray MTA. In group 2, 20 teeth
received 2 mm of white MTA. In group 3, 20 teeth
received 2 mm of light curing glass ionomer cement
(Vitremer). In group 4, 20 teeth received 5 mm of
gray MTA. In group 5, 20 teeth received 5 mm of white MTA. In group 6, 20 teeth received 5 mm of light
curing glass ionomer cement. The teeth in the positive control group received no barrier material, and the
teeth in the negative control group were covered with
nail polish. Each tooth was then bleached using sodium perborate and water. The bleaching agents were
replaced every 7 days over three weeks. Following the
bleaching procedures, teeth were decoronated, immersed in methylene blue dye for 48 hours, and then
were decalcified, dehydrated, and cleared.
The maximum linear leakage in apical direction,
through the interface between the dentin and barrier
material, was recorded for each specimen. The leakage scores from 0 to 4 were assigned as follows: Score
0 no leakage, score 1 from 0.1 to 0.5 mm of leakage,
score 2 from 0.6 to 1 mm of leakage, score 3 from 1.1
to 2 mm of leakage, score 4 from 2.1 mm to apical
foramen.
The maximum amount of linear dye penetration
was measured under a stereomicroscope and statistical analyses were carried out using the MannWhitney test.
Results
All controls behaved as expected (Table I). There
was no statistically significant difference in leakage
between gray MTA and white MTA (p>0.001). Both
groups that received 2 mm of gray and white MTA
leaked significantly less than group 3 that received
2 mm of glass ionomer cement (p<0.001). There was
no statistically difference in leakage between the groups 4, 5 and 6 that received 5 mm of barrier material
when compared with each other.
Table I. The leakage scores of coronal barriers
Coronal barrier
Microleakage values
n
0 1 2 3 4
Gray mineral trioxide aggregate (2 mm) 6 10 3 1 - 20
Gray mineral trioxide aggregate (5 mm) 8 11 1 - - 20
White mineral trioxide aggregate (2 mm) 7 11 2 - - 20
White mineral trioxide aggregate (5 mm) 9 10 1 - - 20
Vitremer (2 mm) 2 7 6 3 2 20
Vitremer (5 mm) 5 10 4 1 - 2098 • June 2010 • Gulhane Med J Koçak et al.
Discussion
Penetration of bleaching agents towards the periodontal ligament may cause localized damage and initiate an inflammatory reaction resulting in bone and
root resorption (5). The results of our study showed
that although the placement of intraorifice barrier
did not completely prevent the dye leakage through
the dentin-barrier material interface, since significantly increased leakage was observed in the positive
control group, the use of barriers during bleaching
barriers is essential. This result is agree with that of
Heller et al. who used different materials for the same
purpose (19).
Coronal leakage can be evaluated with different
methodologies. Among these we could mention
fluid filtration (20) and bacterial leakage tests (21).
However, we agree with Aqrawabi (22) and Xavier et
al. (23) who stated that if root end filling materials
were able to prevent the leakage of small particles
such as dye, they would possibly prevent the penetration of bacteria and their sub-products. Therefore,
the microleakage of all tested materials were evaluated with dye penetration method.
The ability of dye penetration methods to demonstrate microleakage has been emphasized in various
studies (24,25). In our study the leakage of coronal
barriers were compared using the dye penetration
method. All specimens in positive control group leaked throughout the canal, thus confirming that
coronal barrier material was necessary to prevent
microleakage.
Smith et al. recommended that a minimum of
2 mm thickness of barrier material was required to
prevent the oxygen liberated from the bleaching (6).
Therefore minimum thickness of barriers evaluted in
the present study was applied as 2 mm.
Previous leakage studies revealed various results.
According to Matt et al. 5 mm thickness of gray MTA
demonstrated less leakage than white MTA, apically
(26). In contradistinction, Tselnik et al. evaluated the
leakage of white MTA, gray MTA and resin-modified
glass ionomer and found no difference between the
groups which is similar to the results of the present
study (8). Despite the various results, both studies
recommended gray and white MTA as a coronal or
apical barrier. Barrieshi-Nusair and Hammad reported the mineral trioxide aggregate may be preferred
over glass ionomer instead of one step technique as
a seal intracoronally following root canal treatment
to prevent coronal microleakage (27). Analogously,
the results of the present study showed that 2 mm
thickness of both tested MTA leaked significantly less
than light curing glass ionomer. Similar with the results of the present study, Brito-Júnior et al. reported
that MTA presented higher sealing ability than glass
ionomer based cement (28).
Vitremer presented the highest rates of dye penetration and in some samples it showed total penetration
of methylene blue. Vitremer was tested by Pretorius
& Van Heerden and presented excellent results (18).
On the other hand, our results are in accordance with
other studies in which glass ionomer cement was not
good in preventing apical microleakage (29,30).
In conclusion, within the limitations of the methodology applied, the results indicated that regardless
of the thickness of the barrier, both gray and white
MTA provided good coronal seal and decreased the
amount of coronal leakage that may lead to provide
higher success rate.