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Submit Date : 2022-02-19 • Accept Date : 2022-04-05 • Available online: 2022-03-30 • DOI : 10.21608/edj.2022.117395.1956
Print ISSN 0070-9484 • Online ISSN 2090-2360
Conservative Dentistry and Endodontics
EGYPTIAN
DENTAL JOURNAL
Vol. 68, 1937:1943, April, 2022
Article is licensed under a Creative Commons Attribution 4.0 International License
* Associate Professor, Department of Endodontic, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
** Associate Professor, Department of Endodontic, Faculty of Dentistry, Modern science and arts – MSA Egypt.
*** Associate Professor of Oral Biology, Faculty of Oral and Dental Medicine, Future University, Cairo, Egypt.
INTRODUCTION
An efcacious root canal treatment depends on
accurate diagnosis followed by efcient mechani-
cal preparation and irrigation of root canal systems
together with adequate 3D obturation and coronal
seal(1). Literatures documented that after instrumen-
tation, the root canal walls are masked with an irreg-
ular 1–2 µ thickness layer known as the smear layer
(2,3) which comprises dentine debris, pulp remnants,
and microorganisms (4).
A COMPARATIVE SEM ASSESSMENT FOR THE ABILITY
OF PIPS, XP-FINISHER AND PUI TO ELIMINATE SMEAR
LAYER AND OPEN DENTINAL TUBULES
Maram Farouk Obeid*, Elham Elshaboury** and Raneem F. Obeid***
ABSTRACT
Aim: This study aimed to assess the removal of smear layer from the dentinal surfaces after
canal cleaning and irrigants activation with different systems (Conventional needle irrigation, PUI,
PIPS, XP-Finisher).
Methodology: Seventy human single rooted maxillary incisors were instrumented up to X5
(50/6) Protaper Next rotary system. The irrigation activation was performed using either: PIPS,
PUI, XP-Finisher, or conventional irrigation. Samples were cut lengthwise, then examined under a
scanning electron microscope. Data were analyzed with Kruskal- Wallis test. Signicant difference
between the groups was recorded statistically in the total scores of the smear layer on dentinal wall
(P<0.05).
Results: PIPS and XP-Finisher groups showed more smear layer removal than the conventional
and PUI groups and this was statistically signicant (P<0.05). This was clearly presented by opened
dentinal tubules in photomicrograph of SEM.
Conclusion: With the constraints of this in vitro study, PIPS and XP-Finisher are better in
eliminating smear layer from dentinal walls.
KEYWORDS: PIPS; PUI; XP-Finisher; irrigation.
(1938) M F Obeid, et al.E.D.J. Vol. 68, No. 2
Even with the prevailing argument on the inu-
ence of smear layer on the adequacy of root canal
cleanliness, researchers concluded that the smear
layer is usually infected and preserve bacteria in
dentine (5-7). Moreover, it acts as a substrate for mi-
croorganisms (8,9). The existence of this layer inhibits
or slows up the diffusion of intracanal medicaments
and sealers into dentinal tubules boosting the risk
of reinfection (1,4,10). Furthermore, adequate radicu-
lar seal cannot be guaranteed as it prevents direct
contact of sealers with the inner walls of dentine,
and this acts as an avenue for microleakage and de-
creases the prognosis after endodontic treatment (4,5).
With reference to the aforementioned , eliminat-
ing smear layer is mandatory. The usual followed
protocol is by irrigating the canal with sodium hy-
pochlorite (NaOCl) followed by Ethylene Diamine
Tetra-Acetic acid (EDTA), each for 1 min (7). Still,
the reality showed limited ability of routine irrig-
ant solution to penetrate and reach the complicated
anatomy of root canal system (11-13). Thus, many fac-
tors were modied during preparation to maximize
irrigation penetration such as the degree of canal
taper and preparation size (14). Agitation of the ir-
rigants inside the canal was another targeted fac-
tor. This can be categorized into two broad classes,
manual or machine-assisted agitation which shows
better results (15,16).
Ultrasonic devices had been used for this pur-
pose in what is known as passive ultrasonic irriga-
tion (PUI) (17). This count on the cavitation phenom-
ena that is coupled with the acoustic streaming and
resulted from the oscillation of ultrasonically driven
non-active smooth le, to push irrigants into the
ramication of root canal (18).
Another example for the agitation devices is
the one presented lately the XP-Endo nisher (XP-
Finisher) NiTi le (FKG, Dentaire SA, Switzer-
land). The producer dues that this le can efciently
cleanse the complex anatomy of root canals and
accredited this property to its unique design with
small size central core (ISO 25 diameter) and 0% ta-
per beside its high exibility as it is made with Max-
Wire NiTi alloy (18,19). This le is straight and in
martensite phase at room temperature (20°). While,
when it is inside the tooth at body temperature (35°),
it curves and changes to austenite phase(20).
Laser activation of irrigants has been estab-
lished recently to be used for irrigant agitation (16,21).
Photon-induced photo acoustic streaming (PIPS)
employs an Erbium:Yttrium–Aluminum-Garnet
(Er:YAG) laser at 2940 nm (LightWalker AT; Fo-
tona, Ljubljana, Slovenia). It relies on the superior
absorption of this laser wavelength by the irrigant
that lls up the coronal chamber (22,23). With each
shot of laser, the irrigant uid is immediately heated
up beyond its boiling point forming a vapor bubble
at the tip of the ber. The later enlarges, reaching
its extreme and then collapses resulting in a cavi-
tation effect. This spectacle generates agitation in
the form of turbulent photoacoustic streaming of the
uid through all canals’ complexities (24).
Apparently, there are inadequacy in records
comparing these irrigant agitation systems regarding
the ability to eliminate the smear layer in literature.
Hence, the goal of this in vitro study is to assess
by scanning electron microscope (SEM) images
the dentinal surfaces after canal shaping with a
traditional NiTi rotary system, under irrigation
activation with different systems (PUI, PIPS, XP-
Finisher) regarding the elimination of smear layer.
Our null hypothesis is that there are no differences
in smear layer elimination with different irrigant
agitation systems used.
MATERIALS AND METHODS
This research was done in full accordance with
ethical principles, including the World Medical As-
sociation Declaration of Helsinki (version 2008).
Seventy extracted human single rooted maxillary
central incisors with intact roots, mature apices and
without any resorption or visible cracks were used.
PIPS, XP-FINISHER VS PUI FOR SMEAR LAYER REMOVAL (1939)
The reason of extraction was unknown. Teeth were
checked by conventional radiograph to prove the
existence of single canal and absence of calcica-
tions, resorption and/or other anomalies then all
teeth were stowed in saline at room temperature.
Access cavity was drilled, and patency of the canals
was established using #K-le10 (MANI, Matsutain
Seisakusho Co., Tochigi-Ken, Japan), then root ca-
nals were instrumented with Protaper Next rotary
system till X5 (50/6) using X-Smart Endo Motor
(Dentsply Sirona, Pennsylvania, USA) at speed of
300 RPM and 2.5 N.Cm torque following the manu-
facturer guides. All samples were irrigated with 3ml
of 2.5% NaOCl (Wizard, Guided Chemical) solu-
tion using a 30-gauge Navitip needle (NaviTip; Ul-
tradent, South Jordan, UT) between les and after
nishing the instrumentation. Finally, the apex was
coated with hot glue then wrapped with soft wax to
resemble closed end channels (25).
Samples grouping and testing:
The nal irrigation consisted of 5 mL of
5.25% NaOCl followed by 5 mL 17%EDTA and
nally 5 mL of 5.25% NaOCl separated by 5mL
normal saline. Samples were distributed randomly
according to the irrigation activation protocol into
four groups:
PIPS Group (n=20): A cylindrically tapered
PIPS® tip 400/14 was used to activate irrigants.
The laser was Er:YAG (LightWalker®, Fotona,
d.o.o., Ljubljana, Slovenia) of 2940 nm wavelength
operated at 20 mJ, 15 Hz, 0.3W, and 50 μs (SSP)
for 30 seconds on, then 30 seconds off. The PIPS
tip was placed in coronal cavity near canal orices.
This cycle was performed six times (i.e., total of
180 seconds of activation).
PUI Group (n=20): irrigants were activated with
ultrasound (EMS, Nyon, Switzerland), using #20
Irrisafe ultrasonic les (Satelec, Acteon, Merignac,
France) that was introduced inside the canal, without
touching the walls, 1 mm shorter than the working
length. The power setting of 4 was used for 3 cycles
of 1 minute.
XP-Finisher Group: (n=20) The irrigants acti-
vation was done using XP-Finisher NiTi le oper-
ated at 800 rpm and 1 Ncm torque using endodon-
tic motor (X Smart, Dentsply-Maillefer). 6-7mm
lengthwise movements were done for 1 minute and
repeated 3 times.
Control Group (CSI) (n=10): The irrigants were
delivered using a 30-gauge Navitip (NaviTip; Ultra-
dent, South Jordan, UT), without any kind of irrig-
ant agitation nor activation.
Sample preparation and evaluation:
To facilitate samples’ splitting, a cone of gutta-
percha was tted within the canal then a longitudinal
groove on the external surface of the root was cut
with a diamond disc without reaching the canal
lumen. The specimens were separated into halves
with a chisel then coded. Samples were dehydrated
for 1 hour per solution in 50%, 70%, 80%, and
100% ethanol then left to dry. After spluttering
with gold–palladium, samples were assessed under
SEM (SEM; JSM–5600LV, JEOL, Tokyo, Japan)
at 20 kV and images at 2000× have being taken.
The residual smear layer in the apical, middle, and
coronal thirds was scored by two separate observers
following 4-point scoring system (26). Score1, no
debris and opened dentinal tubules; score 2, debris
covering less than 50% of the area and opened
dentinal tubules; score 3, debris covering more than
50% of the area and opened dentinal tubules with;
and score 4, dentinal tubules covered by debris in
more than 90% of the examined area.
Data were studied using the statistical package
for social sciences, version 23.0 (SPSS Inc.,
Chicago, Illinois, USA). The qualitative variables
were presented as number and percentages. The
Comparison between groups with qualitative data
was done using Chi-square test and Fisher’s exact
test instead of Chi-square test only when the expected
(1940) M F Obeid, et al.E.D.J. Vol. 68, No. 2
count in any cell less than 5. The condence interval
was set to 95% and the margin of error accepted was
set to 5%. P-value <0.05 was considered signicant.
RESULTS
Data are presented in table1 and gure 1. It
shows highly statistically signicant difference
between groups in all thirds (P<0.001). In the
apical third, there was a signicant difference
between the groups except PUI versus control group
(P=0.141) and PIPS versus XP-nisher (P=0.298).
In the remaining areas, again, there was a signicant
differences between all groups except PIPS and
XP-nisher (P=0.344, P=0.055) in the middle and
coronal thirds respectively.
SEM images (g.2) showed that the control
group had the uppermost amount of remaining
smear layer followed by PUI group while PIPS and
XP-nisher showed the least.
Fig. (1): stacked bar chart showing the percentage score for the
remaining smear layer in all thirds of the root canals in
each group
TABLE (1): Smear layer score percent for the tested groups at the coronal, middle, apical thirds
Thirds Score
Control PIPS PUI XP n.
x2p-value
No. %No. %No. %No. %
Apical
1 0 0.0% 15 75.0% 0 0.0% 12 60.0%
71.606 <0.001**
2 0 0.0% 5 25.0% 0 0.0% 6 30.0%
3 4 40.0% 0 0.0% 15 75.0% 2 10.0%
4 6 60.0% 0 0.0% 5 25.0% 0 0.0%
Middle
1 0 0.0% 16 80.0% 1 5.0% 14 70.0%
63.045 <0.001**
2 0 0.0% 4 20.0% 12 60.0% 4 20.0%
3 6 60.0% 0 0.0% 6 30.0% 2 10.0%
4 4 40.0% 0 0.0% 1 5.0% 0 0.0%
Coronal
1 0 0.0% 10 50.0% 2 10.0% 17 85.0%
57.348 <0.001**
2 0 0.0% 9 45.0% 8 40.0% 3 15.0%
3 6 60.0% 1 5.0% 8 40.0% 0 0.0%
4 4 40.0% 0 0.0% 2 10.0% 0 0.0%
Chi-square test
x20.000 5.846 21.071 3.961
p-value 1.000 0.211 0.002* 0.411
PIPS, XP-FINISHER VS PUI FOR SMEAR LAYER REMOVAL (1941)
DISCUSSION
Smear layer is generated after instrumenting the
root canals. Till now, there is no proof suggesting that
its elimination is clinically of great importance (27),
but it is quietly clear that this allows better cleaning
of the canal walls and improves the adaptation of
root lling materials (5). It is known that this layer
is formed of organic content eliminated by NaOcl
irrigant and inorganic content eliminated by EDTA
(7,9). But still there are many arguments regarding
the ideal method of irrigant activation to adequately
eliminate this layer and open the dentinal tubules(28).
Thus, the aim of our research was to compare
different irriga entional needle irrigation regarding
their efcacy in eliminating the smear layer from
root canal wall.
While an in vivo scenario is preferred, a compar-
ative in vitro study design was preferred to guarantee
adequate management of variables and consistency
of results. Single rooted teeth with single canal were
chosen since they have an oval cross section and the
cleaning ability of rotary instruments is restricted
by the rounded cross-sectional design of les, leav-
ing large areas of canal walls untouched with accu-
mulation of hard-tissue debris (29). Teeth apices were
closed to simulate in vivo circumstances as regards
gas trap in root canal and to allow the root canal
space to act as a reservoir for irrigant during the ir-
rigation/activation process (25).
The ndings obtained in this study demonstrated
that the effectiveness of all systems in the elimina-
tion of the smear layer drops apically in all groups
and this is consistent with previous studies reveal-
ing that irrigation are least effective in the apical
region (11-13). The incompetence in eliminating the
smear layer apically was justied by the truth that
the apical is tinier in size than the other thirds with a
superior level of tubular sclerosis (30).
Our results revealed that the conventional
irrigation exhibited the least ability in removing
smear layer in all thirds and this was in agreement
with Saber and Hashem (31). The change of smear
layer elimination between PIPS and XP-nisher
was not statistically signicant, but both devices
were signicantly superior to the control and PUI
groups.
Even though the capability of PUI to eliminate
the smear layer has been stated formerly (32) our re-
sults revealed no difference between PUI and con-
trol group. This agrees with Saber and Hashem (31)
who concluded that nal irrigant activation with
PUI was not efcient in removal of the smear layer.
On the other hand, PIPS and XP-Finisher eliminat-
ed more smear layer apically. For PIPS, our nd-
ings were in a line with Ayranci et al. (30) who stated
that irrigant activation by PIPS using the Er: YAG
laser was more efcient in smear layer removal in
both middle and apical regions compared to the
ultrasonic activation. They attributed this to the
Fig. (2): SEM photomicrograph (X2000) showing: Control
group (rst column): closed dentinal tubules (DT) more
than the opened ones in all thirds (A,B,C) PUI group
(second column): opened DT in the middle third (E).
Apical and coronal thirds showed obliterated DT by
smear layer (D,F) PIPS group (Third Column): opened
DT in all thirds (G,H,I). Few DT in the coronal third
are obliterated (I) XF Finisher group (fourth column):
opened DT in all third (J,K,L). (Red arrows: opened
DT, Yellow arrows: Obliterated DT).
(1942) M F Obeid, et al.E.D.J. Vol. 68, No. 2
photomechanical and photothermal effects cor-
related with Er:YAG laser which leads to the for-
mation of shock waves causing quick changes in
pressure and elevated amplitude resulting in a pow-
erful acoustic streaming of uids (26). For XP-Fin-
isher, Sousa et al (33) claimed that this is due to its
manufacturing from Max-NiTi wire making it very
exible. The later can expand its range to 100-fold
greater than a corresponding le allowing better
cleaning of the canal in inaccessible areas (3). More-
over, Živković et al (34) conclusion was like ours
in which they stated that the rotary NiTi XP-endo
Finisher was a procient irrigation in instrumented
canals and could eliminate smear layer and dentin
debris from impenetrable areas.
The ndings of our research have revealed
that the irrigation activation systems varied in the
degree of cleansing promoted in root canal walls.
Subsequently, the null hypothesis was denied.
Upcoming studies are necessary to validate the
usefulness of these systems regarding the overall
disinfection of the root canal system using different
irrigants.
CONCLUSION
Apparently, it can be assumed that irrigation
activation is mandatory as it improves the elimination
of the smear layer from the canal walls. None of the
methods used were capable to have smear layer free
walls however, PIPS and XP-Finisher were better
than PUI and conventional irrigation.
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