Endodontie articol

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Comparative evaluation of the shaping ability of

WaveOne, Reciproc and OneShape single-file

systems in severely curved root canals of

extracted teeth

S. E. D. M. Saber1, M. M. Nagy1 & E. Sch€afer2

1Department of Endodontics, Faculty of Dentistry, Ain Shams University, Cairo, Egypt; and 2Central Interdisciplinary

Ambulance in the School of Dentistry, University of M€unster, M€unster, Germany

Abstract

Saber SEDM, Nagy MM, Sch€afer E. Comparative

evaluation of the shaping ability of WaveOne, Reciproc and

OneShape single-file systems in severely curved root canals

of extracted teeth. International Endodontic Journal , 48, 109 –

114, 2015.

Aim To compare the shaping ability of WaveOne,

Reciproc and OneShape single-file systems in

severely curved root canals in extracted human molar

teeth.

Methodology Sixty mandibular molars with me-

sio-buccal canals with curvatures ranging between

25° and 35° and radii of curvature ranging between

4 and 9 mm were divided into three groups of 20

teeth each: group W (WaveOne), group R (Reciproc)

and group O (OneShape). Using standardized pre- and

post-instrumentation radiographs, straightening of

canal curvatures was determined using the NIH

Image J software. A double-digital standardized radio-

graphic technique was used to determine apical trans-

portation at 0.5 mm from the working length

(1.5 mm coronal to the major foramen). Preparation

time and instrument failures were also recorded. Data

were analysed using one-way analysis of variance

(ANOVA) and post-hoc Tukey-test.

Results During root canal preparation, no instru-

ments fractured but all OneShape instruments weredeformed after preparation of four canals. The use of

OneShape resulted in significantly greater canal

straightening and apical transportation than

WaveOne and Reciproc (P < 0.05), with no signifi-

cant differences between WaveOne and Reciproc

(P > 0.05). Instrumentation with OneShape was sig-

nificantly faster than with WaveOne and Reciproc

(P < 0.05), whilst Reciproc was significantly faster

than WaveOne (P < 0.05).

Conclusions All instruments were safe to use.

Reciproc and WaveOne instruments respected the ori-

ginal canal curvature better than OneShape files. The

use of OneShape instruments required less time to

prepare the curved canals compared with Reciproc

and WaveOne.

Keywords: apical transportation, canal straighten-

ing, OneShape, Reciproc, shaping ability, WaveOne.

Received 2 February 2014; accepted 25 March 2014

Introduction

Shaping of the root canal is one of the most importantsteps in root canal treatment (Peters 2004). It is essen-

tial for the efficacy of all subsequent procedures,

including chemical disinfection and root canal filling

(Hulsmann et al. 2005). However, the complex anat-omy of the root canal system and the inherent limita-

tions of instruments pose several challenges that can

affect treatment outcome (Lin et al. 2005, Sch€afer &

B€urklein 2012).

Recently, different single-file systems have been

marketed with the ability to prepare root canals with

Correspondence: Shehab El-Din Mohamed Saber, Department of

Endodontics, Faculty of Dentistry, Ain Shams University, El-Rehab

City (81-11-11), 11841 Cairo, Egypt (Tel.: 002 01001413734;

Fax: 002 022260983; e-mail: [email protected]).

© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd International Endodontic Journal, 48, 109–114, 2015

doi:10.1111/iej.12289

109



only one instrument. WaveOne (Dentsply Maillefer,

Ballaigues, Switzerland) and Reciproc (VDW, Munich,

Germany) instruments are manufactured from

M-wire alloy. This alloy is characterized by an

increased flexibility and cyclic fatigue resistance in

comparison with martensitic NiTi (Shen et al. 2006).

These instruments are used in a reciprocal motion inwhich the values of clockwise and counter clockwise

rotations are different. The reciprocating movement

relieves stress on the instrument and, therefore,

reduces the risk of cyclic fatigue caused by tension

and compression (You et al. 2010, Plotino et al.

2012). A large rotating angle in the cutting direction

(CCW) allows the instrument to progress towards the

apex, whereas a smaller angle in the opposite direc-

tion (CW) allows the file to be immediately disen-

gaged, thereby eliminating the threading and binding

of the instrument (Plotino et al. 2012). The One-

Shape file by Micro Mega (Besancon, France) is

another single-file system, but used in continuous

clockwise rotation. These instruments have an inno-

vative design with three different cross-sectional

areas over the entire length of the working part and

have a variable pitch and a noncutting safety tip

(B€urklein et al. 2013). The design features of Reci-

proc, WaveOne (B€urklein et al. 2012) and OneShape

have been described in detail previously (B€urklein

et al. 2013).

The aim of the present study was to compare the

shaping ability of WaveOne, Reciproc and OneShape

single-file systems in severely curved root canals of

extracted human molar teeth. The null hypothesistested was that there is no difference between Wave-

One, Reciproc and OneShape single-file systems

regarding canal straightening, apical transportation

or preparation time when preparing severely curved

root canals.

Materials and methods

Selection of teeth

A total of 60 extracted human permanent mandibu-

lar first molars with at least one curved mesial root

and curved mesio-buccal (MB) root canal were

selected. Coronal access was achieved using diamond

burs, and the canals were controlled for apical

patency with a size 10 K-file (Mani, Utsunomiya,

Tochigi, Japan). Only teeth with intact mature root

apices were included. Teeth that did not allow the

insertion of a size 10 K-file to the major foramen or

the passive placement of a size 15 K-file to within

1 mm of the foramen were discarded. Moreover, teeth

with root canals wider than size 20 were also dis-

carded. This was checked with size 20 silver points

(VDW).

Standardized digital radiographs were taken prior

to instrumentation with a size 15 K-file inserted intothe curved canal. Each tooth was placed in a radio-

graphic mount made of silicone-based impression

material (Optosil P Plus; Heraeus Kulzer, Hanau, Ger-

many) to maintain a fixed film-object-source position.

The radiographic mount compromised a radiographic-

sensor holding paralleling device (Howe; Kerr,

Orange, CA, USA), which held the digital sensor

(Sopro; Acteon, Merignac, France) and was aligned so

that the long axis of the root canal was parallel and

as near as possible to the surface of the sensor. The

X-ray tube, and thus the central X-ray beam, was

aligned perpendicular to the root canal. The exposure

parameters (0.08s; 70 kV, 8 mA) were the same for

all radiographs. The acquired digital radiographs were

transferred to AutoCAD 2008 (Autodesk, San Rafael,

CA, USA), and the angle and radius of curvature of

each root canal were determined as described previ-

ously (Sch€afer et al. 2002).

Only teeth whose radii of curvature ranged between

4 and 9 mm and whose angles of curvature ranged

between 25° and 39° were included. On the basis of

the degree and the radius of curvature, and the dis-

tance between the apex and the cemento-enamel junc-

tion, the teeth were allocated into one of the three

experimental groups: WaveOne (W) group, Reciproc(R) group and OneShape (O) group. The homogeneity

of the groups with respect to the afore mentioned three

parameters was assessed using analysis of variance

(ANOVA) and post-hoc Tukey-test (Table 1).

Root canal instrumentation

The working length (WL) was established with a size

10 K-file, using 2.5% sodium hypochlorite (Clorox,

Cairo, Egypt) as a lubricant, which was introduced

into each canal until the file tip became visible at the

major foramen under a surgical microscope (OMS

2350; Zumax, Jiangsu, China) at a 6.99 magnifica-

tion. Subsequently, the file was withdrawn until the

tip was tangential to the major foramen. The rubber

stop was adjusted to the nearest flat anatomic land-

mark on the tooth, which was chosen as a reference

for the measurement of the root canal. The distance

between the file tip and the rubber stop was measured

Shaping ability of single-file systems Saber et al.

© 2014 International Endodontic Journal. Published by John Wiley & Sons LtdInternational Endodontic Journal, 48, 109–114, 2015110



under the same magnification with a millimetre ruler.

Then, 1 mm was subtracted from this measurement,

and the resulting value was taken as the WL.

Instrumentation was performed by a single opera-

tor in accordance with the manufacturers’ recommen-

dations. Primary WaveOne files and Reciproc R25

instruments were operated in a reciprocating motion

powered by a torque-limited electric motor (Silver

Reciproc; VDW) using pre-set adjustments, whilst

OneShape instruments (size 25, taper 0.06) were

operated in continuous rotation motion using an elec-

tric motor with torque and speed control (iEndo dual;

Acteon).

All instruments were used in a slow in-and-out

pecking motion with an amplitude of about 3 mm.

The flutes of the instruments were cleaned after three

in-and-out movements (pecks) and the root canal was

flushed with 2 mL of a 2.5% NaOCl solution using a

30-gauge needle (NaviTip; Ultradent, South Jordan,

UT, USA) that was inserted as deeply as possible into

the canal without binding. Apical patency was main-

tained using a size 10 K-file. Once the rotary instru-

ment had negotiated to the end of the canal and hadrotated freely, it was removed. Each instrument was

used to prepare four canals only as the single-file sys-

tems are recommended to be used as single-patient

instruments, and, most of the time, four canals is the

maximum number of root canals per tooth. At the

end of canal preparation, the final instrument was

inserted into the canal at WL, and a radiograph was

taken using the same technique as described above.

Only one canal was instrumented in each tooth.

The time for canal preparation was recorded and

included total active instrumentation, cleaning of the

flutes of the instruments and irrigation whilst the

time required to place and adjust the rubber stops to

working length was not included.

Evaluations

All root canal preparations were completed by one

operator, whilst the assessment of the canal curvatures

and apical transportation were carried out by a second

examiner who was blind in respect of all experimental

groups.

Based on the canal curvatures assessed before and

after instrumentation, canal straightening was deter-

mined as the difference between them.

A double-digital standardized radiographic tech-

nique was used to compare apical transportation

between groups. Adobe Photoshop (Adobe Systems,

San Jose, CA, USA) was used to superimpose post-

and the corresponding pre-instrumentation image.

The central axes of the size 15 K-file and the master

file were superimposed. Small translation and rotation

movements were used to achieve a perfect fit between

the two images. Image-J analysis software (Image-J

v1.44; US National Institutes of Health, Bethesda,

MD, USA) was used to measure apical transportation

at 0.5 mm short of the WL (Fig. 1).

The time for canal preparation was recorded using

a digital chronometer (Timex, Middlebury, CT, USA).

The changes of working length and the number of

fractured and permanently deformed instruments dur-

ing enlargement were also recorded.The data were distributed normally (Shapiro-Wilk-

test) and were analysed statistically using the analysis

of variance (ANOVA) and post-hoc Tukey-test at a signif-

icance level of P < 0.05.

Results

During the preparation of the curved root canals, no

instrument fractured, but all OneShape instruments

were deformed after preparing four canals. All

canals remained patent following instrumentation.

With all instruments, no canal had overextension of

preparation and no loss of working length was

noticed.

The use of OneShape files resulted in significantly

greater canal straightening and significantly greater

apical transportation than WaveOne and Reciproc

(P < 0.05), with no significant differences between

WaveOne and Reciproc (P > 0.05). OneShape files

Table 1 Characteristics of curved root canals (n = 20 teeth per group) (CEJ = cemento-enamel junction)

Instrument

Curvature (degrees) Radius (mm) Distance Apex-CEJ (mm)

Mean SD Min Max Mean SD Min Max Mean SD

WaveOne 31.38 3.7 25 39 6.65 1.3 4.9 9 9.5 0 .6

Reciproc 30.12 4.5 25 39 6.39 1.5 4.1 8.7 9.4 0 .9

OneShape 30.94 4.1 25 38 6.56 1.9 4.3 8.9 9.7 0 .4

P value 0.659 0.871 0.356

Saber et al. Shaping ability of single-file systems

© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd International Endodontic Journal, 48, 109–114, 2015 111



Prior to instrumentation of the curved canals, no

glide path was created as an inclusion criterion was

that all teeth had to allow the passive placement of a

size 15 K-file to within 1 mm of the apical foramen.

Thus, for all canals, the width near the apex was

approximately compatible with size 15, which is rec-

ommended by the manufacturer of Reciproc whenpreparing curved root canals.

The results of the present study revealed that the

use of WaveOne and Reciproc instruments resulted in

significantly less canal straightening and significantly

less apical transportation than the use of OneShape

instruments (P < 0.05; Table 2). This can be attrib-

uted to several reasons: first WaveOne and Reciproc

instruments are made from M-wire alloy whereas

OneShape is made from conventional martensitic

NiTi. M-wire NiTi is characterized by superior flexibil-

ity compared with conventional NiTi (Shen et al.

2006). Pereira et al. (2012) showed that M-Wire had

physical and mechanical properties that can render

root canal instruments more flexible and fatigue resis-

tant than those made from conventionally martensitic

NiTi. Secondly, WaveOne and Reciproc were used in

a reciprocal motion. This working motion has been

associated with well-centred preparations and reduced

incidence of procedural errors (Varela-Patino et al.

2010, Franco et al. 2011). Furthermore, this motion

extends the lifespan of instruments in comparison

with continuous rotation (De-Deus et al. 2010, You

et al. 2010). Thirdly, the differences may be explained

by the different design features of the instruments

used.WaveOne instruments have variable cross-sections

along the working part that change from a concave

triangular cross-section with radial land at the tip to

a neutral rake angle with a triangular convex cross-

section in the middle part and near the shaft

(B€urklein et al. 2012). The radial lands in combina-

tion with the reciprocating working motion are

claimed to keep the WaveOne instrument centred

whilst advancing apically into the root canal (Webber

et al. 2011). Reciproc instruments have an S-shaped

cross-section with two sharp cutting edges along the

entire working part (B€urklein et al. 2012). Obviously,

instruments having this S-shaped cross-sectional

design are characterized by a relatively good shaping

ability when used either in full clockwise rotation

(Mtwo, VDW; F360, Brasseler, Lemgo, Germany) (Vel-

tri et al. 2005, Sch€afer et al. 2006, B€urklein et al.

2013, ) or in a reciprocating motion (B€urklein et al.

2012, 2013).

Whilst OneShape instruments have a variable 3-

cutting-edge design at the tip region that progres-

sively changes from 3 to 2 cutting edges in the mid-

dle part, whilst near the shaft, the instrument has 2

cutting edges (B€urklein et al. 2013). This design used

in continuous rotation at a relatively higher speed

allows the instruments to rapidly progress into thecurved root canals. This could create some stress that

might have resulted in the observed canal straighten-

ing and apical transportation.

Although significant differences regarding canal

straightening and apical transportation were

obtained, from a clinical point of view, these differ-

ences might be of no importance (Fig. 1). Taking into

account that severely curved canals were instrumen-

ted, the clinical relevance of a maximum difference in

canal straightening of mere 0.4 mm caused by the

different instruments remains questionable. Thus, it

can be concluded that all three instruments tested

maintained the original canal curvature well.

The results of this study are in agreement with sev-

eral previous studies (B€urklein et al. 2012, 2013, You

& Cho 2012, Marzouk & Ghoneim 2013, Capar et al.

2014). B€urklein et al. (2012, 2013) reported that

WaveOne, Reciproc and OneShape maintained the

original curvature of severely curved canals in

extracted teeth well. Also Capar et al. (2014) using

cone-beam computed tomographic (CBCT) imaging

found that WaveOne, Reciproc and OneShape main-

tained root canal curvature equally well and pro-

duced similar canal transportation during the

preparation of mesial canals of mandibular molars.Likewise, You & Cho (2012) using simulated canals

in resin blocks found that WaveOne and Reciproc

produced similar canal straightening and maintained

the original canal curvature equally good and better

than ProTaper (Dentsply Maillefer) and ProFile

(Dentsply Maillefer).

OneShape instruments required significantly less

time to prepare the root canals than Reciproc, whilst

Reciproc was significantly faster than WaveOne

(P < 0.05). The significant difference between Wave-

One and the two other instruments can be explained

by the different cross-sectional designs. OneShape and

Reciproc possess a markedly smaller core diameter

than WaveOne and thus the chip space of these

instruments is greater than that of WaveOne. An

increased chip space is associated with an increased

debris-removal capacity and efficiency of these instru-

ments (Webber et al. 2011, B€urklein et al. 2012,

2013). The difference between OneShape and

Saber et al. Shaping ability of single-file systems

© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd International Endodontic Journal, 48, 109–114, 2015 113



Reciproc may be attributed to the different working

motions and the different rotational speeds. OneShape

was used with a rotational speed of 400 rpm whilst

Reciproc instruments operate at about 282 – 300 rpm

with a 150-158-degrees counterclockwise rotation

followed by a 30-34-degrees clockwise rotation (Kim

et al. 2012, Fiedler 2014) However, from a clinicalpoint of view the differences between the three differ-

ent instruments, although statistically significant,

might be of no importance.

Conclusions

All instruments were safe to use. Reciproc and Wave-

One instruments respected the original canal curvature

better than OneShape files. The use of OneShape instru-

ments required less time to prepare the curved canals

compared with Reciproc and WaveOne. The clinical

relevance of these differences is likely to be minimal.

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