Assessment of apically extruded debris produced by the singlefile ProTaper F2 technique under reciprocating movement
Gustavo De-Deus, DDS, MS, PhD,a Maria Claudia Brandão, DDS, MS,b
Bianca Barino, DDS, MS,b Karina Di Giorgi, DDS, MS,b
Rivail Antonio Sergio Fidel, DDS, MS, PhD,c and Aderval Severino Luna, PhD,d Rio de
Janeiro, Brazil
VEIGA DE ALMEIDA UNIVERSITY AND RIO DE JANEIRO STATE UNIVERSITY
Objective. This study was designed to quantitatively evaluate the amount of dentin debris extruded from the apical
foramen by comparing the conventional sequence of the ProTaper Universal nickel-titanium (NiTi) files with the
single-file ProTaper F2 technique.
Study design. Thirty mesial roots of lower molars were selected, and the use of different instrumentation techniques
resulted in 3 groups (n ⫽ 10 each). In G1, a crown-down hand-file technique was used, and in G2 conventional
ProTaper Universal technique was used. In G3, ProTaper F2 file was used in a reciprocating motion. The apical finish
preparation was equivalent to ISO size 25. An apparatus was used to evaluate the apically extruded debris. Statistical
analysis was performed using 1-way analysis of variance and Tukey multiple comparisons.
Results. No significant difference was found in the amount of the debris extruded between the conventional sequence
of the ProTaper Universal NiTi files and the single-file ProTaper F2 technique (P ⬎ .05). In contrast, the hand
instrumentation group extruded significantly more debris than both NiTi groups (P ⬍ .05).
Conclusions. The present results yielded favorable input for the F2 single-file technique in terms of apically extruded
debris, inasmuch as it is the most simple and cost-effective instrumentation approach. (Oral Surg Oral Med Oral
Pathol Oral Radiol Endod 2010;110:390-394)
Currently, nickel-titanium (NiTi) rotary systems are
useful in dealing with the cleaning and shaping limitations imposed by the complex anatomy of root canal
systems.1-3 The development of NiTi rotary systems
has broken with some paradigms related to root canal
preparation. As a consequence, the performance of the
rotary systems is under constant evaluation4 owing to
the large increase of new files and systems. However,
because of the complexity of the NiTi rotary systems,
the issue of instrument fracture and elevated cost are
acknowledged as current shortcomings.
Recently, a new approach using the ProTaper F2 in a
reciprocal movement was published, thereby presenting
a new perspective for NiTi files.5 The use of the singlefile NiTi technique to prepare the whole root canal is
very advantageous, because the learning curve can be
considerably reduced with the reduction of the enda
Associate Professor, Department of Endodontics, Veiga de Almeida
University.
b
Department of Endodontics, Rio de Janeiro State University.
c
Adjunct Professor and Chairman, Department of Endodontics, Rio
de Janeiro State University.
d
Department of Analytical Chemistry, Rio de Janeiro State University.
Received for publication Nov 16, 2009; returned for revision Apr 5,
2010; accepted for publication Apr 16, 2010.
1079-2104/$ - see front matter
© 2010 Published by Mosby, Inc.
doi:10.1016/j.tripleo.2010.04.020
390
odontic armamentarium. Moreover, the single-file NiTi
technique tends to be more cost-effective than the conventional multifile NiTi rotary systems.
Although the first clinical impressions of the singlefile NiTi technique appeared to be promising, other
important parameters still need to be properly assessed
by both laboratory and clinical studies. The amount of
material extruded from the apical foramen is one of the
main concerns related to an instrumentation technique.
Dentin debris, pulp tissue remnants, microorganisms,
and intracanal irrigants may be extruded from the apical
foramen during canal instrumentation. Extrusion of
these elements may cause undesired consequences,
such as induction of inflammation and postoperative
pain and delay of periapical healing.6,7 Although all
instrumentation techniques apically extrude some
amount of debris,8 there are notable differences
among the techniques. It is worthwhile to note that,
while apical extrusion of dentinal debris and irrigants
has been observed with the use of all presently known
root canal preparation techniques and instruments, less
dentinal debris extrusion was associated with the use of
motor-driven rotary instruments.9,10 Because rotary instruments can differ greatly in their design, type of
blades, use, number of files, and kinematics, different
amounts of apically extruded debris can be found between the systems.11
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Volume 110, Number 3
The present study was designed to quantitatively
evaluate the amount of dentin debris extruded from the
apical foramen by comparing the conventional sequence of the ProTaper Universal NiTi files with the
single-file ProTaper F2 technique. Conventional crowndown hand-file instrumentation was used as a reference.
The null hypothesis tested was that there are no differences in the amount of debris extruded apically between
the 2 ProTaper techniques.
MATERIALS AND METHODS
Specimen selection
This study was revised and approved by the Ethics
Committee, Nucleus of Collective Health Studies of
Rio de Janeiro State University. One hundred fifty left
and right mandibular first molar teeth were collected
from the tooth bank of Rio de Janeiro State University.
To select only moderately curved mesial roots, radiographs of each tooth were taken, digitized, and stored
electronically. Root canal curvature was determined
based on the angle of curvature initiated at the coronal
aspect of the apical third of the root using Schneider’s
method.12 Angles of curvature were measured using an
image analysis program (AxioVision 4.5; Carl Zeiss
Vision, Hallbergmoos, Germany). Only those roots
with angles of curvature ranging between 10° and 20°
(moderate curvatures) were selected. In addition, only
mesial root canals with an initial apical size equivalent
to a size 10 K-file were selected for the study. Up to this
point of specimen selection, 57 molar mesial roots met
the selection criteria, and 30 were included in the
present study. Working length was established by subtracting 1 mm from the canal length. After measurement, the length of all mesial roots was standardized to
13 mm to prevent the introduction of confounders
which might contribute to variations in the preparation
procedures.13 Additionally, the foramen diameter of all
teeth was standardized to a size 15 K-file. Owing to the
anatomic features, it was impossible to follow the predetermined apical preparation in 20 of the specimens.
Therefore, only 37 molar teeth met the standardization
values previously mentioned. Therefore, to achieve
equal groups, 7 teeth were discarded, leaving a total
sample size of just 30 mesial roots. The teeth were
disinfected in 0.5% chloramine T, stored in distilled
water at 4°C and used within 6 months after extraction.
The use of different instrumentation techniques resulted
in 3 groups with 10 specimens each (G1, G2, and G3).
The groups were randomly distributed using a computer
algorithm (http://www.random.org). Each tooth was labeled with a random 5-digit alphanumeric code corresponding to 1 of the 3 experimental groups to remove
potential operator bias.
De-Deus et al. 391
Common irrigation parameters
Irrigation was performed in exactly the same manner for all specimens using a 5 mL disposable plastic
syringe (Ultradent Products, South Jordan, UT) with
30-gauge Endo-Eze Tips (Ultradent) placed passively into the canal, up to 5 mm from the apical
foramen without binding. Aspiration was performed
using SurgiTip tips (Ultradent) attached to a highspeed suction pump.
Between each file, root canals were irrigated with
0.5 mL bis-distilled and deionized water for 1
minute. The flow of irrigation (1 mL/min) was determined with an automatic syringe pump (SP100i;
World Precision Instruments, Sarasota, FL). At the
end of the instrumentation, each tooth was flushed
with 2 mL irrigant to remove any debris adhered to
the root canal walls.
Instrumentation
Group 1: Hand-file technique. The coronal and middle third of each canal was prepared using GatesGlidden drill (Dentsply/Maillefer, Ballaigues, Switzerland) sizes 4, 3, and 2 up to the beginning of the canal
curvature. The apical third was prepared with Flexofile
(Dentsply/Maillefer) sizes 50, 45, 40, 35, 30, and 25 at
working length (WL) using the balanced force movement.14 Thus, the canals in this group were instrumented with 9 instruments.
Group 2: Conventional ProTaper Universal technique. ProTaper Universal files were driven at 300 rpm
with an endodontic micromotor (XSmart; DentsplyMaillefer) in a conventional rotary movement as follows: 1) S1 file (one-third of WL); 2) SX file (one-half
of WL); 3) S2 file (two-thirds of WL); 4) F1 file (full
WL); and 5) F2 file (full WL). As a result of the
ProTaper sequence, all of the canals in this group were
instrumented with 5 NiTi instruments.
Group 3: Single-file ProTaper F2 technique. The
entire canal preparation was completed with a ProTaper F2 file used in a reciprocating motion. The
reciprocating movement is a clockwise (CW) and
counterclockwise (CCW) movement. The ATR Vision (ATR; Pistoia, Italy) motor allows programming
for reciprocating movement at four-tenths of a circle
CW and two-tenths of a circle CCW. The F2 file was
driven at 400 rpm with a 16:1 reduction ratio contraangle handpiece.
Debris collection
The apparatus used to evaluate the collection of
apically extruded debris had very minor adaptations
from that described previously15 (Fig. 1). Briefly, a 10
mL ampule with a rubber stopper was adjusted for use
392
De-Deus et al.
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September 2010
Fig. 2. Box plots of the amount of extruded debris, illustrating the median, minimum, and maximum values, as well as
the standard deviation data of each experimental group.-
Fig. 1. Schematic illustrating the modified apparatus used to
evaluate the collection of apically extruded debris.-
in this experiment. The plastic assay tubes were individually preweighed 3 times with a 10⫺5-g precision
analytic microbalance (Model 1101; ElbaTech, Isola
d’Elba, Italy) to obtain the mean weight of each one.
By using a heated instrument, a hole was made
through the center of every rubber stopper in which
the root was adapted by using pressure. A 30-G
needle was inserted into the rubber stopper to balance internal and external pressures, allowing for
debris extrusion. All of the plastic assay tubes were
covered with black tape to blind the operator during
canal instrumentation.
All of the teeth were instrumented into the collection
assembly. After instrumentation, collection assembly
was placed in a dry-heat oven at a constant temperature
of 140°C for 5 hours, allowing for irrigant evaporation.
Three consecutive weight measurements were taken for
each collection assembly, with the mean value recorded. The weight of the extruded debris was determined by subtracting the weight of the preweighed
collection assembly from the final weight of the collection assembly.
Statistical analysis
As the preliminary analysis of the raw pooled data
revealed a bell-shaped distribution (D’Agostino and
Person omnibus normality test), statistical analysis was
performed using parametric methods—1-way analysis
of variance. Post hoc pairwise comparisons were performed using Tukey multiple comparisons. The alphatype error was set at .05.
RESULTS
The median, minimum, and maximum values, as
well as the standard deviation data of each experimental
group, are shown in Fig. 2. Based on the statistical
results, no significant difference was found in the
amount of the debris extruded between the conventional sequence of the ProTaper Universal NiTi files
and the single-file ProTaper F2 technique (P ⬎ .05).
The hand instrumentation group extruded significantly
more debris than both of the other NiTi groups (P ⬍
.05).
DISCUSSION
The present study showed no significant difference in
the amount of debris extruded between the conventional sequence of the ProTaper Universal NiTi files
and the single-file ProTaper F2 technique. Therefore,
the null hypothesis was plainly accepted. The improved
apical control of debris extrusion promoted by both
NiTi techniques is in line with earlier reports.9,10,16
Among several hand-instrumentation kinematics, the
balanced force technique is regarded to promote less
apical extrusion of debris.17 Therefore, the balanced
force technique was chosen to be used as the reference
for comparison in the present study.
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Volume 110, Number 3
The amount of dentin debris was collected following
the Myers and Montgomery method (1991),15 but the
collection apparatus was slightly modified to make it
more simple, practical, and affordable. Moreover, it is
worth mentioning that the possibility of some fingertip
contamination was eiminated in the present study because, throughout all experimental procedure, there was
no direct contact between assembly and the operator’s
fingertips.
In the present experimental design, 2 different variables were present in the NiTi groups: the number of
files used and the movement kinematics. Therefore, it is
not possible to isolate the influence of each variable on
the present result. The experimental design used in this
study is appropriate, because the purpose was not to
determine the relationship between the number of files
or the movement kinematics with the amount of debris
extruded apically. Therefore, it is worthwhile to stress
that the present study is unable to confirm the influence
of the type of movement in the amount of debris
extruded apically. A further appropriate experimental
design is required to isolate the influence of the reciprocating movement on the amount of the extruded
debris.
Admittedly, the number of specimens used in each
experimental group (n ⫽ 10) is low, considering that
the standard deviation was somewhat high. On the
other hand, very stringent inclusion criteria were applied and the study was carefully controlled throughout
the experimental procedures. Therefore, the demonstrated effect of canal preparation technique in the
amount of debris extruded appears to be robust and
reliable. To confirm the experimental reliability of the
method used, a bell-shaped distribution of the raw
pooled data was revealed by D’Agostino and Person
omnibus normality test. Thus, statistical analysis was
performed using parametric methods, and, no doubt,
this feature of the data is due to the stringent inclusion
criteria used as well as the use of experimental groups
with a proper number of specimens to detect significant
differences.
To the best of the present authors’ knowledge, there
has been no peer-reviewed study in which molars were
used to assess the amount of dentin debris extruded.
Usually, single-root teeth were used, because of the
ease in set up of the collector apparatus. However, it
can be speculated that the canal preparation of singleroot teeth tends to extrude less debris, because the
cleaning and shaping procedures are easier and more
predictable. With the clear purpose of approximating
the challenging clinical situation, mesial roots of mandibular molars were chosen for the current evaluation.
Thus, the amount of dentin debris extrusion was as-
De-Deus et al. 393
sessed during the instrumentation of teeth with more
intricate anatomy.
CONCLUSIONS
From a clinical point of view, the present results are
favorable for the single-file F2 technique, inasmuch as
it is the most simple and cost-effective instrumentation
approach. However, apical control of extruded debris is
just 1 aspect that an instrumentation technique needs to
have tested. Other factors of the root canal preparation
with the single-file F2 technique still require solid laboratory-based tests before the indication of large and
longitudinal clinical studies; researching the involvement of the risk zone in the mesial root of mandibular
molars, apical transportation, debridement ability, and
fracture susceptibility all represent further priorities of
research for the F2 single-file technique.
REFERENCES
1. Thompson SA, Dummer PMH. Shaping ability of NT Engine
and McXim rotary nickel-titanium instruments in simulated root
canals. Part 1. Int Endod J 1997;30:262-9.
2. Schäfer E. Shaping ability of Hero 642 rotary nickel-titanium
instruments and stainless steel hand K-Flexofiles in simulated
curved root canals. Oral Surg Oral Med Oral Path Oral Radiol
Endod 2001;92:215-20.
3. Schäfer E, Lohmann D. Efficiency of rotary nickel-titanium
FlexMaster instruments compared with stainless steel hand KFlexofile. Part 2. Cleaning effectiveness and instrumentation
results in severely curved root canals of extracted teeth. Int
Endod J 2002;35:514-21.
4. Peters OA, Peters CI, Schönenberger K, Barbakow F. ProTaper
rotary root canal preparation: assessment of torque and force in
relation to canal anatomy. Int Endod J 2003;36:93-9.
5. Yared G. Canal preparation using only one Ni-Ti rotary instrument: preliminary observations. Int Endod J 2008;41:339-44.
6. Seltzer S, Naidorf IJ. Flare-ups in endodontics: I. Etiological
factors. J Endod 1985;11:472-8.
7. Seltzer S, Naidorf IJ. Flare-ups in endodontics: II. Therapeutic
measures. J Endod 1985;11:559-67.
8. VandeVisse J, Brilliant JJD. Effect of irrigation on the production of extruded material at the root apex during instrumentation.
J Endod 1975;1:243-6.
9. Beeson TJ, Hartwell GR, Thornton JD, Gunsolley JC. Comparison of debris extruded apically in straight canals: conventional
filing versus Profile .04 taper series 29. J Endod 1998;24:18-22.
10. Ferraz CC, Gomes NV, Gomes BP, Zaia AA, Teixeira FB,
Souza-Filho FJ. Apical extrusion of debris and irrigants using
two hand and three engine-driven instrumentation techniques. Int
Endod J 2001;34:354-8.
11. Tanalp J, Kaptan F, Sert S, Kayahan B, Bayirl G. Quantitative
evaluation of the amount of apically extruded debris using 3
different rotary instrumentation systems. Oral Surg Oral Med
Oral Path Oral Radiol Endod 2006;101:250-7.
12. Schneider SW. A comparison of canal preparations in straight
and curved root canals. Oral Surg Oral Med Oral Path Oral
Radiol Endod 1971;2:271-5.
13. Nguy D, Sedgley C. The influence of canal curvature on the
mechanical efficacy of root canal irrigation in vitro using real-
394
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September 2010
De-Deus et al.
time imaging of bioluminescent bacteria. J Endod 2006;32:
1077-80.
14. Roane JB, Sabala CL, Duncanson MG Jr. The “balanced force”
concept for instrumentation of curved canals. J Endod 1985;11:
203-11.
15. Myers GL, Montgomery S. A comparison of weights of debris
extruded apically by conventional filing and Canal Master techniques. J Endod 1991;17:275-9.
16. Kuştarci A, Akpinar KE, Er K. Apical extrusion of intracanal
debris and irrigant following use of various instrumentation
techniques. Oral Surg Oral Med Oral Path Oral Radiol Endod
2008;105:257-62.
17. Al-Omari MA, Dummer PM. Canal blockage and debris extrusion with eight preparation techniques. J Endod 1995;21:
154-8.
Reprint requests:
Prof. Gustavo De-Deus
R. Desembargador Renato Tavares, 11, ap.102
Ipanema—Rio de Janeiro—RJ
22411-060
Brazil
endogus@gmail.com