EndoCal 10 Obturation Voids in Root Canal and Isthmus of a
Human Premolar:
A Synchrotron micro-CT Imaging Study
Assem Hedayat
1
and Pengyu Wu
2
1
College of Dentistry, University of Saskatchewan, 105 Wiggins Rd., Saskatoon, Canada
2
Department of Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, Canada
Keywords: Apex, Isthmus, Synchrotron-Radiation-based X-ray, micro-CT, Endodontic Therapy, Root Canal, EndoCal
10.
Abstract: The objective of this research is to detect and characterize voids in an Endocal 10 obturated human premolar
using synchrotron-radiation-based micro-computed tomography (SRµCT) and 3D visualization. Also, the aim
is to investigate the extent of voids present in a fine structure such as an isthmus following obturation. We
scanned an extracted human premolar that was obturated with EndoCal 10 using the Bio-Medical Imaging
and Therapy (BMIT) 05ID-2 beamline at the Canadian Light Source. We applied the non-destructive
monochromatic X-ray beam at 47 keV, and compiled 4.3 µm pixel size images utilizing a AA-40
(HAMAMATSU) beam monitor synchronized with a (HAMAMATSU C9300-124) charge-coupled camera.
We used Fiji for reconstructing the images and Avizo 9.0 for 3D rendering. The results showed voids in
different parts of the obturation as well as a partially obturated isthmus. Miicro-CT and 3D visualization show
that voids exist in the pulp chamber, root canal, and isthmus following obturation with EndoCal 10 during
endodontic therapy. We categorized the isthmus as a type V one. The study also highlights the reasons
contributing to the difficulty of obturating the isthmus. The variation in isthmus’ diameter, its irregular
branching, the presence of pulp tissue, as well as its angular orientation with respect to the root canals are
some of the reasons that impede the flow of EndoCal 10 through it.
1 INTRODUCTION
EndoCal 10 is a calcium oxide based material used in
endodontic therapy. In order to obturate a root canal,
a blend of calcium oxide, zinc oxide, and an excipient
is mixed with water and ethylene glycol and applied
(ALBUCA©, 2007). The reactions taking place lead
to the expansion of the EndoCal as it cures (Guigand
et al. 1997, Goldberg et al. 2004). Studies concluded
that EndoCal 10 is an effective sealant in endodontic
therapy (Goldberg et al. 2004, Ghaziani and Sadeghi
2008).
The criterion to evaluate the obturation totality of
a material during endodontic treatment is the
adequacy of filling root canals. It was concluded from
a micro-CT study that different obturating materials
exhibited a certain degree of voids present. These
inadequacies in obturation occurred at a significantly
higher degree in the apical region of the teeth (Wolf et
al. 2014).
In general, root canal isthmuses are prevalent in
human teeth and are classified into different types
(Hsu and Kim 1998). The presence of tissue remnants
and the associated microorganisms in these isthmuses
may affect the success of endodontic therapy. It is
indispensable to seal off isthmuses during endodontic
treatment (Von Arx, 2005). The use of micro-CT to
characterize the obturation of Isthmuses showed
partial filling that may have been caused by debris
from hard tissue and remnants of pulp tissue (Oh et.
Al. 2016).
There are no micro-CT studies that were pursued
to delineate the obturation characteristics of EndoCal
10 inside the tooth structure where it is applied.
Examples of these structures are root canal apices and
isthmuses. The objective of this research is to
delineate the degree of adequacy of Endocal 10 as an
obturating material during endodontic therapy using
the micro-CT capability of the Bio-Medical Imaging
and Therapy (BMIT) 05ID-2 beamline at the
Canadian Light Source, and to characterize the voids
present in an isthmus and a root canal.
This is a pilot study based on a case where the
extracted human premolar was obturated with
Hedayat, A. and Wu, P.
EndoCal 10 Obturation Voids in Root Canal and Isthmus of a Human Premolar: A Synchrotron micro-CT Imaging Study.
DOI: 10.5220/0006582900430049
In Proceedings of the 11th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2018) - Volume 2: BIOIMAGING, pages 43-49
ISBN: 978-989-758-278-3
Copyright © 2018 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
43
EndoCal 10. Accordingly, we did not pursue a
comparison with more teeth and other materials used
in endodontic treatment.
2 METHODS
2.1 Premolar Endodontic Therapy
The two-rooted extracted human premolar used in
this study was amongst 12 other teeth selected from
the tooth bank (College of Dentistry, University of
Saskatchewan) and screened for having intact roots as
examined by a conventional X-ray machine
(Carestream CS2200, Carestream Health Inc.,
Vaughan, Canada). We stored the premolar in
Carolina solution (Carolina Biological Supply
Company, Burlington, NC, USA) at all times. We
summarize the endodontic therapy that was pursued
as follows:
1. We used a high-speed driven endodontic
diamond bur to penetrate the pulp chamber.
2. We utilized a sequence of stainless steel Kerr
Dental K-Flex endo hand files sizes 10, 15, 20,
and 25 Kerr, Orange, CA, USA) to widen the root
canals.
3. Irrigation with 5.25% sodium hypochlorite was
necessary after applying every file.
4. The crown-down technique was then carried out
employing SybronEndo K3 Engine Files (K
Dental Inc., Markham, ON, Canada) lubricated
with Glyde File-Prep RC Conditionar (Patterson
Dental, St. Paul, MN, USA). Irrigation and
drying were always carried out after every file.
5. We then applied EndoCal 10 (ALBUCA,
Montreal, QC, Canada) using a Lentulo spiral to
obturate the premolar.
6. Finally, we etched the inner walls of the premolar
above the obturation with 37% phosphoric acid,
rinsed it, dried it, covered it with 3M Scotchbond
Universal Adhesive (3M ESPE, St. Paul, MN,
USA), and restored it with 3M Filtek Supreme
composite (3M ESPE, St. Paul, MN, USA).
2.2 Synchrotron Scanning
We scanned the premolar using the Bio-Medical
Imaging and Therapy (BMIT) 05ID-2 beamline at the
Canadian Light Source (CLS). We followed the same
procedure detailed in one of our previous studies
(Hedayat et al. 2016). In this work, we subjected the
premolar to the non-destructive monochromatic X-
ray beam at 47 keV, and compiled 4.3 µm pixel size
images utilizing a AA-40 (HAMAMATSU) beam
monitor synchronized with a (HAMAMATSU
C9300-124) charge-coupled camera.
2.3 Image Reconstruction and 3D
Rendering
We used Fiji for reconstructing the images and Avizo
9.0 (FEI, Hillsboro, OR, USA) for 3D rendering. We
have used Avizo 9.0 in a previous study (Hedayat et
al. 2016), and found it a powerful tool for analyzing
micro-CT acquired data.
3 RESULTS
We used Avizo 9.0 for 3D visualization of the
premolar, and observed three distinct features in the
images: a vertical fracture along the side of one of
the roots, voids within the obturated pulp chamber
and apex of the nonfractured root, and partial
obturation within the isthmus between the two root
canals. Since we have already prepared a manuscript
identifying and analyzing the cause of the vertical
fracture along one side of one of the roots, the latter
two observations are addressed in this manuscript.
3.1 Voids in EndoCal 10 Obturated
Structures
It is clear from Figure 1(a) and (b) that one root
fractured while the other one exhibited obturation
voids at its apex. Arrow A points toward the void
while arrow B points to the fractured root.
Figure 1(a): Two roots of the premolar, one exhibiting a
crack while the other showing obturation inadequacy at its
apex.
BIOIMAGING 2018 - 5th International Conference on Bioimaging
44
Figure 1(b): Two roots of the premolar, one exhibiting a
crack while the other showing voids within the obturation
at its apex.
The voids in EndoCal 10 were not limited to the
apex of the root, but were also present in areas within
the obturated pulp chamber as shown in Figure 2(a).
The arrow “V” points to the void within the axial
section, as well as on the gray value profile plot in
Figure 2(b).
Figure 2(a): Axial section of the pulp chamber showing
void “V”.
Figure 2(b): Gray value profile plot reflecting the features
along the line in Figure 2(a) and especially void “V”.
3.2 Partial Obturation of Isthmus
We used Avizo 9.0 for 3D rendering of an isthmus
within the premolar. The arrow in Figure 3 points to
the isthmus which extends between the two root
canals. We were interested to learn about the extent
of EndoCal obturation through the isthmus, and
accordingly compiled a series images of sagittal and
axial sections of the area surrounding it.
Figure 3: Isthmus between the two root canals of the
premolar.
Figure 4(a) to 4(g) is a series of images of sagittal
sections illustrating the extension of the isthmus
between the two root canals. The arrows in all images
point to the isthmus. All images showed the EndoCal
as it partially obturated the isthmus from the left side.
It is significant to mention that some of the sagittal
and axial sections showed the presence of tissue
within the isthmus. For example, in Figure 4(e), while
arrows “A” and “B” point to the isthmus structure,
arrow “C” points to the tissue inside the isthmus. The
EndoCal 10 Obturation Voids in Root Canal and Isthmus of a Human Premolar: A Synchrotron micro-CT Imaging Study
45
appearance of the Endocal tissue inside the isthmus is
different and clearly distinguishable from that of
EndoCal 10.
Figure 4 (a) to (g): Series of Sagittal sections showing
partial obturation of the ishmus by EndoCal 10.
The axial section in Figure 5(a) illustrates the
partial obturation of the isthmus at one end with
EndoCal 10. The profile plot of gray value in Figure
5(b) shows the presence of EndoCal 10 at the peak
“B”. In contrast, the axial sections in Figures 6(a) and
7(a) shows the absence of EndoCal 10 at point “B”,
which is also reflected in the profile plots of the gray
value in Figures 6(b) and 7(b).
BIOIMAGING 2018 - 5th International Conference on Bioimaging
46
Figure 5(a): Axial section showing EndoCal 10 partially
obturating the isthmus.
Figure 5(b): Profile plot of gray value reflecting the features
along the line in 5(a).
Figure 6(a): Axial section showing the isthmus.
Figure 6(b): Profile plot of gray value reflecting the features
along the line in 6(a).
EndoCal 10 Obturation Voids in Root Canal and Isthmus of a Human Premolar: A Synchrotron micro-CT Imaging Study
47
Figure 7(a): Axial section showing the isthmus.
Figure 7(b): Profile plot of Gray value reflecting the
features along the line in 7(a).
4 DISCUSSION
Through synchrotron-radiation-based micro-
computed tomography (SRµCT) and 3D rendering,
we achieved the objective of delineating voids in an
extracted human premolar obturated with EndoCal
10. Using this non-destructive technique, we also
accomplished the aim of studying the degree of void
prevelance in an isthmus post obturation with
Endocal 10.
The high degree of fluidity of EndoCal 10 during
thorough mixing of its powder and liquid components
clearly suggests that the material has the capability to
flow throughout the prepared structures and obturate
them adequately during endodontic therapy.
Although this was observed in crevices and cracks
through 3D visualization at high resolution, there
were voids in the obturation in some areas of the pulp
chamber and apex of one root. Figure 1(b) and 2(a)
show the voids present in the pulp chamber and root
apex, respectively. This supports what was reported
earlier (Wolf et al. 2014) that obturating materials
exhibit some degree of voids present. In this case, the
voids may be attributed to the entrapment of air
bubbles during the obturation process. This also
signifies that although Endocal 10 expands following
its mixing and activation, the expansion does not
engulf and fill the gaps completely.
Visualizing the isthmus between the root canals at
a high resolution and in 3D, as shown in Figure 3, we
concluded the following:
1. The isthmus is a continuous one connecting both
root canals, and accordingly can be classified as
a type V isthmus as defined in the literature (Hsu
& Kim 1998).
2. Some 2D and 3D images showed remnants of
pulp tissue inside the isthmus.
3. The isthmus was partially obturated and Endocal
10 was able to flow to a certain extent from one
end as shown in the series of images in Figure 4.
This is an indication that no hard debris resulting
from the preparation of the root canals plugged
the isthmus.
4. Through 3D visualization, we observed that the
geometry of the isthmus is tubular in structure. It
is narrow at the root canal connecting ends and
has dead-end branches emerging from it. The
isthmus’ diameter increases to a maximum in
between its two ends, which causes a pressure
drop in the Endocal’s flow through it. The
pressure drop is an impeding factor to the flow of
Endocal 10 through the isthmus.
5. As shown in Figures 3 and 4g, the isthmus is
slanted downwards from the left root canal to the
right one. Accordingly, it was easier for the
EndoCal to flow downwards and partially
obturate the isthmus at the left end, rather than
flow upwards at the right end.
This is a single case pilot study that we plan
to expand on in the future. We plan to pursue a
comparative study that includes several teeth
obturated with Endocal 10. We also plan to study the
obturation inadequacies in teeth using other materials
BIOIMAGING 2018 - 5th International Conference on Bioimaging
48
during endodontic treatment. We will apply the same
techniques in data acquisition and processing as we
did in this study.
5 CONCLUSIONS
1. Similar to other obturating materials used in
endodontic therapy, voids may appear in parts of
the pulp chamber, apical region of the root canal,
and isthmus following the application of
EndoCal 10.
2. As illustrated through 3D rendering, the root
canal isthmus in this study is characterized by a
non-uniform diameter, branches, and tissue
within it.
3. With conventional endodontic therapy, it is not
possible to completely obturate an isthmus with
a structure similar to the one visualized in this
study. This is attributed to its varying diameter,
its branching architecture, and the tissue
remaining in it.
4. Through 3D visualization of the isthmus between
the two root canals in this study, we categorize
this isthmus as a type V.
6 FUTURE WORK
1. Future work, that will be comparative in nature,
is planned to apply the imaging technology and
3D rendering technique we followed in this study
to more cases of teeth obturation with Endocal 10
during endodontic therapy. The research will
delineate the voids in the obturated roots, and
evaluate the degree of obturation in the isthmuses
that might be present in those teeth.
2. It will be of value to pursue the study on other
obturating materials used in endodontic
treatment. The results will be also compared.
3. We can quantify the volume of voids and
compare the data acquired from different teeth
and using other obturating materials in future
studies.
ACKNOWLEDGEMENTS
Research described in this paper was performed at the
BMIT facility at the Canadian Light Source, which is
supported by the Canada Foundation for Innovation,
Natural Sciences and Engineering Research Council
of Canada, the University of Saskatchewan, the
Government of Saskatchewan, Western Economic
Diversification Canada, the National Research
Council Canada, and the Canadian Institutes of
Health Research.
We thank Dr. Ning Zhu for his guidance and
assistance throughout our research at (BMIT) 05ID-2
beamline at the Canadian Light Source.
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EndoCal 10 Obturation Voids in Root Canal and Isthmus of a Human Premolar: A Synchrotron micro-CT Imaging Study
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