BALKAN JOURNAL OF DENTAL MEDICINE
GI
CA
L SOCIETY
10.2478/bjdm-2019-0006
ISSN 2335-0245
LO
TO
STOMA
Efficiency of XP Endo Shaper (XPS) and Irrigation
Protocol on the Quality of Cleaning the Apical Third
of Root Canal: SEM Study
SUMMARY
Background/Aim: The aim of this study was to evaluate the efficacy
of new rotary NiTi instrument XP- endo SHAPER (XPS) used with two
irrigation protocols on the root canal cleaning in the apical area. Material
and Methods: The research was conducted on 30 single-rooted teeth
extracted for orthodontic reasons which were divided into the two groups.
Instrumentation of the canals was conducted with XPS instrument and
2% solution of NaOCl was used as irrigant. Instrumentation in the first
group was performed using a conventional continuous irrigation, in the
second group, protocol of final irrigation was performed intermittently in
3 cycles. The SEM analysis of the apical third of the canal was performed
on longitudinal root cross-section standardized photomicrography with a
magnification of 2000X. Results: Results showed that a thicker smear layer
was observed in the first group and with continuous irrigation protocol
(2,10) in relation to the intermittent irrigation protocol in 3 cycles (1,96),
but without significant differences.The walls of the root canal in the apical
third of the samples of the second group were slightly cleaner (73.3%)
in comparison with the teeth of the first group (64, 7%), but also without
significant differences. Conclusions: The use of XPS and 2% solution of
NaOCl in the root canal enables efficient cleaning of the apical third of
tooth. The final irrigation protocol in three cycles improves the efficiency of
the smear layer removal in the apical segment of the canal.
Key words: XP-endo Shaper, Smear Layer, Irrigation Protocol, Apical Third
Introduction
Cleaning and shaping the root canal system is
the most important phase in an endodontic treatment.
However, complex anatomy of a canal often prevents
adequate cleaning of this space using actual instruments
and techniques1,2. A particular problem is the irregularity
of the canal system (isthmus, ramifications, and additional
lateral canals) or apical third of the root canal, which
cannot be reached by most of the instruments, and
almost 30-50% of the surface of the canal walls remains
untouched1,3.
Mechanical instrumentation with manual or
mechanical instruments leads to the formation of smear
Slavoljub Živković,
Milica Jovanović-Medojević, Jelena Nešković,
Marijana Popović Bajić, Marija Živković Sandić
Department of Restorative Odontology and
Endodontics, School of Dentistry, University of
Belgrade, Belgrade, Serbia
ORIGINAL PAPER (OP)
Balk J Dent Med, 2019;31-35
layer and dentin debris on the walls of the canal, and
often to their accumulation in inaccessible areas of the
canal system4,5. In this way there is significant efficiency
reduction of irrigant on the residual bacteria and
significant linkage material disturbance for obturation of
the canal walls3,6,7.
In order to clean the root effectively, type and
quantity of the irrigant or irrigation techniques and
protocol are significant. These intracanal solutions
provide a lubricating effect during instrumentation, have
an antibacterial effect, remove debris and smear layer
from the root canal walls and from inaccessible areas of
the canal system8,9,10.
32
Slavoljub Živković et al.
The most frequently used endodontic irrigant is
sodium hypochlorite (at various concentrations), primarily
due to its antibacterial11 and solvent effect12, although
higher concentrations can cause irritation of the periapical
tissue13. Exceptional and prolonged antibacterial effect of
chlorhexidine on the large number of bacteria in the canal,
makes this irrigant often used in endodontic treatments8,14.
Researches has also shown that it is possible to increase
the efficiency of the irrigant, or to achieve better
penetration and better cleaning of the canal walls using
some forms of solution activation like: ultrasound15,16, a
new instrument XP-endo Finisher1,17 or laser18.
Chemo- mechanical procedure provides a
significantly lower number of bacteria in the canal, but
not complete disinfection of the canal system. In addition,
any available set of manual or mechanical burnishing
tool results in the formation of smear layer and dentin
debridement on processed canal walls2,6,8. For the success
of this endodontic treatment, it is necessary to remove this
layer, and the removal efficiency is significantly affected
by irrigating solutions on the basis of the chelating agent,
which effectively remove the smear layer from all areas of
the canal2,19,20.
The aim of this study was to evaluate the efficiency
of the apical third of the canal after the instrumentation
of the NiTi rotating instrument XP- endo Shaper and the
application of two final irrigation protocols using SEM
analysis.
Material and Methods
The study was conducted on 30 premolars extracted
for orthodontic reasons. Teeth were stored up to the
experiment in a 0.2% solution of thymol, at a temperature
of 4 °C.
Root Canal Instrumentation
In all teeth the access cavity was formed and
established initial passage with K-file #15. The working
length is determined to be 1 mm shorter than the length
at which the tip of the hand file appears on the apical
foramen. To prevent leakage of the solution for irrigation
during instrumentation, a wax ball was placed at the apex
of each root.
The teeth were randomly divided into two groups
(each of 15 teeth) and the complete mechanical
instrumentation was performed by one researcher. As
an irrigant, a 2% solution of NaOCl (Cloraxid 2%,
Cerkamed, Poland) was used, and the canal was washed
with plastic syringes, a volume of 2 ml, and needle size
27. A 4 ml solution for irrigation was used for each canal,
and the flushing protocol lasted 150 sec.
Balk J Dent Med, Vol 23, 2019
The canal instrumentation was carried out in both
groups by the new NiTi rotating instrument XP-endo
Shaper (FKG, Dentaire, Swiss) (dimensions 30/04)21.
This instrument represents a new generation of NiTi
rotating instruments that, thanks to its extraordinary
superelasticity, can change its shape in the canal and thus,
reach inaccessible areas of the canal. A special production
technique and specific geometry of the cutting part
ensures the cleaning and shaping of the canal with only
one instrument (800 rpm).
GROUP 1- In the first group, a conventional
technique of continuous irrigation was applied. The
canal is filled with an irrigant (0.5 ml) and then the
XPS instrument is inserted into the canal with gentle
insertion and withdrawal placed to the working length
(3-5 times for 30 sec). Then the irrigant (0.5 ml) was
re-inserted into the canal and usage of XPS provided the
final apical preparation 8-10 times over 30 sec. The final
irrigation with 2% NaOCl solution was performed after
the completion of the instrumentation with another 3 ml
solution for 90 sec.
GROUP 2- In the second group, XPS instrumentation
was done in the same way as in the first group, but the
final irrigation was performed intermittently in 3 steps (3
times 1ml for 30 sec).
SEM analysis
After finishing the instrumentation, the crowns of all
teeth were cut at the cement-enamel junction and then the
roots were cut with diamond disc (without penetration into
the canal) longitudinally in the vestibulo-oral direction
and separated into two halves with sharp chisel. Obtained
halves were placed on a carrier, gold-coated and analyzed
by SEM (JOEL, JSM, 64660 LV, Japan).
Only an apical third (region 3 mm from the
instrumentation border) was analyzed, so that,
for each sample (half of the teeth) 5 standardized
microphotographs were taken at 2000x magnification.
SEM photographs of teeth samples (300 images) were
analyzed by two researchers who independently rated
each photo. In case of disagreement, it was discussed to
reach a consensus. The evaluation of cleaning efficiency
was based on qualitative estimation of residual smear
layer in the apical segment of the canal with the criteria
presented by Hülsmann et al.22:
Grade 1 - no smear layer, dentinal tubules open,
Grade 2 - small amount of smear layer, several dentinal
tubules open,
Grade 3 - homogeneous smear layer covers the canal
wall, small number of dentinal tubules open,
Grade 4 - the entire wall of the canal covered with smear
layer, no open dentinal tubules,
Grade 5 - non-homogeneous smear layer covering the
entire wall of the canal.
Balk J Dent Med, Vol 23, 2019
Permanent First Molar Tooth Loss 33
The clean wall canal included ratings 1 and 2, and
the wall with the present smear layer grades 3, 4 and 5.
The obtained results were processed in the SPSS 20 (IBM,
CHICAGO) program. Methods of descriptive statistics
and Mann Whitney test were used in statistical analysis.
A)
Results
The results of the analysis of SEM photographs after
the instrumentation and canal irrigation are shown in
Tables 1 and 2 and in Figures 1 and 2. The analysis of the
apical thirds samples indicated mainly clear canal walls,
without the smear layer in both tested groups (Figure 1).
B)
Figure 2. Evaluation of cleaning quality in the apical third of the
canal, A) Samples of the first group where the technique of continuous
irrigation was applied (Grade 3). SEM 2000x, B) Samples of the second
group where the final irrigation was performed by intermittent technique
in 3 steps (Grade 2). SEM 2000x.
Table 2. Evaluation of cleaning quality in the apical third of the
root canal
Cleaning ratings
A)
Figure 1. The representative evaluation microphotographs of the smear
layer in the apex third of the canal
Samples of the first group where the technique of
continuous irrigation (grade 2) was applied. SEM 2000x,
B) Samples of the second group where the final irrigation
was performed by intermittent technique in 3 steps (grade
1). SEM 2000x.
A slightly smear layer was registered in the first
group where the instrumentation was performed using
the XPS instrument and with the continual irrigation
protocol (2,10) in comparison to the second group where
the instrumentation was performed using XPS and an
intermittent 3-step irrigation protocol (1,96), but without
statistically significant differences (Table 1).
Table 1. Evaluation of smear layer in the apical third of the root
canal
Smeared layer ratings
N
Mean SD Med Min max
150
2.10 1.03 2.00 1.00 4.00
Irrigation in 3 steps 150
1.96 0.98 2.00 1.00 4.00
Total
2.03 1.00 2.00 1.00 4.00
Continuous
Group irrigation
Continuous
irrigation
B)
300
The obtained results also indicated cleaner walls
in the apical third of the samples of the second group
(73,3%) compared to the canal walls of the first group
(64,7%) (Figure 2, Table 2).
Good
(Grade 1,2)
With smeared
layer
(Grade 3,4,5)
total
N
97
53
150
%
64.7%
35.3%
100%
N
110
40
150
%
73.3%
26.7%
100%
N
207
93
300
%
69%
31%
100%
Group
Irrigation in
3 steps
Total
Discusion
Although there were earlier controversies,
today there is a generally accepted consensus among
endodontists about the necessity of removing the smear
layer from the walls of the root canal10,11,14. This layer
significantly influences the success of endodontic
treatment because it can contain bacteria and its presence
can reduce the efficacy of intra canal medicaments, or
reduce the adhesion of endodontic sealers to canal walls
during obturation6,7,8.
The possibilities of light microscopy in the debris
and smear layer identification after chemo-mechanical
canal preparation are quite high23), but SEM analysis
is certainly the most reliable and most popular method,
primarily because of the possible magnification and high
image resolution5,8,18.
Studies have confirmed that the smear layer from
the canal walls is easier to remove from the coronal
and middle third2,6,9,18, while the cleaning problem
is particularly pronounced in the area of the apical
third1,11,15,19,24.
34
Slavoljub Živković et al.
These research were realized by an identical protocol
(all canals were processed by one researcher), with
one type of instrument (XPS), with the same amount
and duration of irrigation and with two final irrigation
protocols (2% NaOCl). The obtained results indicated a
very efficient cleaning of the apical segment of the canal
and the walls mostly without a smear layer in both tested
groups. A more efficient removal of the smear layer
and better cleaning was observed after the intermittent
final irrigation protocol in three steps in comparison to
continuous irrigation protocol.
Clean canal walls in apical third of the nearly all
samples could be explained primarily by the simplicity of
canal morphology, but also by the effects of the new XPS
instrument, or by its specific design, at a speed of 800 rpm,
and by the fact that it can change its shape in the canal
during the instrumentation and thus, reach the inaccessible
canal areas17,25. In addition, the extreme flexibility of
the XPS and the working end with 6 cutting edges (with
minimal torque) ensure efficient cleaning of all canal walls
and the apical segment. The formed dentine micro derbis
is easily removed due to the pronounced “turbulence” of
irrigants during instrument rotation in the canal1,15,16,21.
The application of XPS in the chemo- mechanical
canal preparation provides the necessary and sufficient
diameter of the apical preparation (30/04), which is also
a precondition that facilitates cleaning of this part of the
canal1,11,15. Diameter of the apical preparation formed in
this way allows the tip of the needle to easily reach the
apical terminus, which also improves the efficiency of the
irrigant in the removal of the smear layer2,9. One of the
problems of such deep application of irrigation needles
in clinical conditions can be the conveyance of irrigant
(NaOCl) into periapex, which can cause adverse effects
on periapical structures26.
The results comparison of various studies on
the effects of cleansing the apical third is quite
complicated because of both, the different techniques of
instrumentation and irrigation, and different evaluation
methods2. In this study, a 2% NaOCl solution was used as
an irrigant with two final irrigation protocols.
The largest number of researchers agree that the
quality of the cleaning of the canal system depends
largely on irrigants, its quantities, irrigation techniques
and the time of exposure of the canal walls to the irrigants
solution1,3,9,10. The fact is that the solution for irrigation,
quantity and time of action were identical in both groups,
nonetheless, better results could be obtained primarily in
the final irrigation protocol.
An intermittent final irrigation protocol (in 3 steps)
has shown somewhat better results than the conventional
irrigation protocol. During the conventional protocol, the
irrigation solution is mixed with the remains of the smear
layer and debris, which significantly reduces the efficiency,
while the fresh solution during each cycle provides better
canal cleaning1,16. It has also been confirmed that 3 cycles
Balk J Dent Med, Vol 23, 2019
of fresh NaOCl solution increase its cumulative efficiency
as well as efficacy in canal cleaning quality28.
A smaller amount of the smear layer in the apex part
of the canal could be due to the fact that XPS due to the
specific working part of the instrument and higher speeds
during the canal treatment, leads to considerably less
transport of the cut dentine into the apex part of the canal29.
Efficient cleaning of the apical third and clean
walls without smear layer were also observed after the
application of the specific self-adjusting file (SAFSelf Adjusting File) in the canal instrumentation. The
irrigation solution flows through the SAF file to provide a
permanent freshness which is additionally activated by the
movements of the file2.
What is interesting in this study is the fact that the
chemo-mechanical preparation of the canal was done with
only one instrument and thus confirmed that the efficacy
of cleaning does not depend on the number of used
instruments30, but above all from the diameter of apical
preparation1,15,24 or from type, volume, concentration, and
irrigation protocol11,31.
The results of this study indicated that the apical
segment of the canal was clean and without a smear layer
in a high percentage, although only 2% NaOCl solution
was used for irrigation. These findings are inconsistent
with the findings of the authors who suggest that the
removal of the smear layer from the canal walls is mainly
dependent on the usage of chelating agents6,8,19,20.
Conclusions
Within the limitations of this study, it can be
concluded that the chemo–mechanical instrumentation of
root canal using XPS and 2% NaOCl solution provides
efficient cleaning of the apical canal segment, primarily
due to the adequate diameter of the apex preparation and
the specific effect of the new instrument during canal
preparation. The intermittent final irrigation protocol in
three cycles improves the removal of the smear layer in
the apical part of the canal.
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Conflict of Interests: Nothing to declair.
Financial Disclosure Statement: Nothing to declair.
Human Rights Statement: None reguired.
Animal Rights Statement: None reguired.
Received on April 2, 2018.
Revised on Jun 2, 2018.
Accepted on December 2, 2018.
Correspondence:
Slavoljub Živković
Department of restorative odontology and endodontics
School of Dentistry, University of Belgrade
Belgrade, Serbia
e-mail: slavoljub.zivkovic@stomf.bg.ac.rs
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