A comparative evaluation of sealing ability of a new, self-etching, dual-curable sealer: Hybrid Root SEAL(MetaSEAL)Sema Belli, DDS, PhD, Erhan Ozcan, DDS, Oznur Derinbay, DDS, andAyce Unverdi Eldeniz, DDS, PhD Konya, TurkeySELCUK UNIVERSITY

Objective. To assess the long-term sealing ability of a new dual-curable, self-etching, 4-META containing resin-basedsealer: Hybrid Root SEAL (MetaSEAL in the United States) and compare with RealSeal and AH Plus sealers.Methodology. Root canals of 44 extracted and decoronated single-rooted human teeth were instrumented using acrown-down technique with ProFile 0.04 tapered NiTi rotary instruments to ISO size 30 and then to size 45 with K-hand files. Four roots were selected and used as positive and negative controls (n � 2), the rest were randomlydivided into 4 groups (n � 10) and filled using 0.04 tapered size 45 cones as follows: Group 1: AH Plus with gutta-percha; Group 2: Hybrid Root SEAL (MetaSEAL) with gutta-percha; Group 3: Hybrid Root SEAL (MetaSEAL) withResilon point; and Group 4: RealSeal with Resilon point. The quality of seal of each specimen was measured after 1,4, 12, and 24 weeks using a fluid transport model. Measurements were made at 2-minute intervals for 8 minutes. Thedata were calculated as Lp and statistically analyzed using 2-way repeated measures of ANOVA and Bonferronipairwise comparison tests (� � 0.05).Results. There were no significant differences among test materials in terms of fluid microleakage values (P � .126).There were statistically significant differences among the time periods (P � .009) and observed between 1- and 24-week test periods. There was significant interaction between root canal filling materials and time of testing (P � .048).Conclusion. Within the limitations of this in vitro study, it was concluded that recently introduced Hybrid Root SEAL(MetaSEAL) showed similar sealing performance with RealSeal and AH Plus sealers when used either with gutta-percha

or Resilon at 24 weeks. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:e45-e52)

Complete and 3-dimensional impervious obturation ofthe root canal system is of prime clinical importance forthe long-term success of endodontic treatment.1-3 Al-though a number of materials are used for obturation,the most common form of endodontic treatment usesthe combination of gutta-percha cones and sealer.4 Asgutta-percha does not bond to root canal walls, the useof sealers along with well-adapted gutta-percha hasbeen recommended.5 To date, a great variety of end-odontic materials are introduced to the dental commu-nity as a result of manufacturers’ attempts to developnew products having better physical properties than thecommonly used materials. Resilon (Resilon ResearchLLC, Madison, CT) is the first bondable material thathas the potential to challenge gutta-percha as a core.6,7

Its bonding ability is derived from the inclusion of resinwith methacryloxy groups.8 When it is applied using amethacrylate-based sealer to self-etching primer-

Selcuk University, Faculty of Dentistry, Konya, Turkey.Received for publication Dec 13, 2007; returned for revision Jul 26,2008; accepted for publication Jul 31, 2008.1079-2104/$ - see front matter© 2008 All rights reserved.

doi:10.1016/j.tripleo.2008.07.027

treated root dentin, it creates a secondary monoblock.9

Epiphany (Pentron Clinical Technologies, Wallingford,CT) and RealSeal (Sybron Endo, Orange, CA) sealershave similar chemical composition with different brandnames and are designed for bonding simultaneously tointraradicular dentin and polycaprolactone-based Resi-lon.10 RealSeal exhibited rheological properties suit-able for clinical use and defined as a dental resincomposite material.11 Published literature about RealSealis sparse and long-term evaluations are lacking.

Hybrid Root SEAL (MetaSEAL) (Sun Medical, To-kyo, Japan; Parkell Inc., Farmingdale, NY) is a newdual-cure and self-etching resin cement, containing4-methacryloyloxyethyl trimellitate anhydride (4-META)that can be used either with Resilon or gutta-perchaaccording to the manufacturers. Four-methacryloyloxy-ethyl trimellitate anhydride is able to promote monomerdiffusion into the acid-conditioned and underlying in-tact dentin and can produce functional hybridized den-tin with the polymerization.12,13 The formation of hy-bridized dentin is the major mechanism of bonding14

and high-quality hybridized dentin resists acidic chal-lenges.13

AH Plus sealer is known as an epoxy-resin–based

sealer having excellent sealing properties15,16 and is

e45

OOOOEe46 Belli et al. December 2008

considered as the gold standard against which all newsealers and bondable root canal obturation materialsmust be compared.17

Several investigations using different methodologieshave been reported to test different properties of estab-lished resin-based sealers such as adhesion,18-21 adapt-ability,22 scanning electron microscope (SEM) or trans-mission electron microscope (TEM) interfaceevaluation studies,8 and leakage.23 The resistance toleakage is considered to be a basic property that needsto be evaluated for every new root canal filling mate-rial.24,25 It is also necessary to both assess long-termsealing ability of the sealers and short-term sealing as itmay differ with time26 and different physical propertiessuch as viscosity, flow, setting time, film thickness, andshrinkage of the sealers during setting leaving voidsand gradual dissolution.27-30

To the authors’ knowledge, no research has beenpublished yet about the short- and long-term sealingability of Hybrid Root SEAL (MetaSEAL) sealer.Therefore the purposes of this in vitro study were toevaluate the following:

1. The sealing ability of Hybrid Root SEAL (Meta-SEAL) in comparison with AH Plus and RealSeal/Resilon system

2. To determine if Hybrid Root SEAL (MetaSEAL)/Resilon combination is an effective method to re-duce apical leakage

3. To evaluate if the leakage values change at differenttime intervals (1, 4, 12, and 24 weeks)

The null hypothesis was that there are no differences inthe leakage performance of Hybrid Root SEAL (Meta-SEAL) versus RealSeal and AH Plus sealer when eitherused with Resilon or gutta-percha.

MATERIALS AND METHODSSingle-rooted permanent human teeth with straight

root canals, extracted for periodontal reasons were ra-diographically examined to evaluate the root canal mor-phology and stored at �4°C in a physiological salinesolution. Teeth with caries, cracks, and immature api-ces were excluded from the study. Soft tissue remnantsand calculus were removed. Forty-four roots were se-lected for this study and the crowns of the teeth wereremoved using a diamond disc under water cooling atthe cement-enamel junction by leaving a root approxi-mately 14 mm long. The canals were classified as beinground or oval shaped according to the radiographs androot canal orifices. Each group was equally composedof 90% round and 10% relatively oval-shaped canals.The patency of the root canals was verified with #10K-file (Dentsply Maillefer, Tulsa, OK) and to standard-

ize the leakage, the apical foramen area of each root

was enlarged with a 20 K-file. Working length wasestablished by inserting the same file into the canal untilit was just visible at the apical foramen and subtracting1 mm from this length. The canals were then firstinstrumented using a crown-down technique with seri-ally using ProFile 0.04 tapered nickel-titanium (NiTi)rotary instruments (Dentsply, Tulsa Dental, Tulsa, OK)40/.04, 35/.04, 30/.04, 25/.04, 20/0.4, 25/.04, 30/.04 toapical size 30. Hand files with the size 35, 40, and 45(Mani Inc., Tochigi-ken, Japan) were used at apicalforamen to make more controlled enlargement. Afterinstrumentation, the minor diameter was gauged toensure that each foramen at working length was notgreater than a size #45/.02 tapered file.31,32 If a #45/.02file passed the working length, working length diameterwas considered to be greater than an instrument size#45 and the root was not used.

Root canals were irrigated with 3 mL of 5.25%NaOCl solution and 3 mL of 17% EDTA solution forsmear layer removal and final rinse was done with 3 mLof distilled water. The canals were dried with paperpoints (Gapadent Co. Ltd., Xinkou Town, Tianjin,China). Four roots were selected for controls (negativeand positive), kept unsealed, and the rest were ran-domly divided into 4 groups (n � 10). Tug back atworking length was achieved with #45/0.04 tapercones; therefore, obturation of the roots was done usingsingle cone technique with size #45/0.04 cones and oneof the sealers given in Table I as follows:

● Group 1: Size #45/0.04 taper gutta-percha mastercone was fitted to the working length with tug-back.An epoxy resin based sealer AH Plus was then placedinto the root canal with the master cone. The excessmaterial was cleaned with a heated instrument (DenTouch, Kfar-Saga, Israel) and cotton pellets.

● Group 2: Three drops of Hybrid Root SEAL (Meta-SEAL) liquid and 1 cup of Hybrid Root SEAL(MetaSEAL) powder were mixed on a mixing pad.Size #45/0.04 taper gutta-percha points (Dentsply)were coated with the sealer and introduced into thesealer filled root canals. The excess material wasremoved and light-cured for 40 seconds. Excess gutta-percha was then removed using the same device as ingroup 1.

● Group 3: Three drops of Hybrid Root SEAL (Meta-SEAL) liquid and 1 cup of Hybrid Root SEAL(MetaSEAL) powder were mixed on a mixing padand sealer mixture was applied to the canal with alentulo spiral filler. A size #45/0.04 taper Resilonpoint was coated with the sealer and introduced intothe root canal. The excess material was removedfrom the coronal surface and light-cured for 40 sec-

onds.

OOOOEVolume 106, Number 6 Belli et al. e47

● Group 4: RealSeal primer was introduced into thecanal and excessive primer was removed with paperpoints. RealSeal sealer was applied to the canal witha lentulo spiral filler (Dentsply, Maillefer). A size#45/0.04 taper Resilon point was fitted to the work-ing length with tug-back and RealSeal sealer wasplaced into the root canal with the master cone andexcess gutta-percha was removed as in group 1. Thenthe roots were light-cured from the coronal side for40 seconds using a halogen light-curing unit (Lunar,Benlioglu Dental, Istanbul, Turkey) at an intensity of620 mW/cm2.

Coronal parts of all the roots were sealed with tem-porary filling material Cavit G (3M ESPE, Seefeld,Germany) and the specimens were then stored at 37°Cand 100% humidity for 1 week.

EVALUATION OF APICAL LEAKAGEA fluid filtration study design previously reported by

Pashley and Depew33 was used to evaluate the leakage.Temporary filling materials were removed. Apical endof the roots were inserted 3 mm into a silicone tubinghaving an internal diameter of 3 mm and attached to theouter surface of the tube with a cyanoacrylate adhesive.The tube was then connected to a fluid filtration appa-ratus as described by Derkson et al.34 and modified byWu et al.35 for endodontic studies. A polyethylenetubing (Fisher Scientific, Pittsburgh, PA) was used toconnect the pressure reservoir to a 25-�L micropipette(Microcaps, Fisher Scientific, Philadelphia, PA). Addi-tional tubing connected the micropipette to a microsy-ringe (Gilmont Instruments Inc, Great Lakes, NY) andthe silicone tube with the attached root. An air bubblewas introduced into the system using the microsyringeand advanced into the micropipette. All tubing, pipette,and syringe were filled with distilled water under a

Table I. Resin-based root canal sealers evaluated in thSealer Ingredients

AH Plus Paste A: Bisphenol-A epoxy resin, Bisphenotungstate, Zirconium oxide, Silica, Iron oPaste B: N-Dibenziyl-5-oxanonane, TCD-Aminoadamantane, Tricylodecane-diaminaerosil Zirconium oxide, Silica, Silicone o

Hybrid Root SEAL(MetaSEAL)

Liquid: 4-META, monofunctionalmethacrylmultifunctional macrylate monomers andmixture of Zirconium oxide filler, SiO2 fiinitiators.

RealSeal Mixture of PEGDMA, EBPADMA, EDMAsilane-treated barium borosilicate glasses;calcium hydroxide; bismuth oxychloride wphoto initator; stabilizers; and pigment.

pressure of 202 kPa via the use of O2 gas. The sealing

qualities of the samples were quantitated by followingthe progress of this tiny air bubble traveling within themicropipette. “System leakage” was considered as “5minutes” for each sample depending on 2 samples thatwere prepared as “negative control,” which do not leak.A small cavity was prepared on the apical end of thesenonprepared and unfilled roots and the cavities werefilled with SuperBond C&B (Sun Medical, Shiga, Ja-pan) using a brush and powder-liquid technique. Apicalparts were then covered with 2 layers of nail varnish.The fluid flow rate through the 2 unsealed root speci-mens was measured by weighing the amount of waterthat could flow through the needle in 1 minute. Thisvalue served both as a positive control and as 100%leakage, to which the sealed values could be expressed(as a percentage).

Measurements of fluid movement were recorded at2-minute intervals for 8 minutes and averaged. Thequality of seal of each specimen was measured at 1, 4,12, and 24 weeks. The access cavities were coveredwith temporary filling material after each measurementand 0.02% sodium azide was added to the storagesolution to prevent bacterial colonization. The sampleswere kept in 100% humid conditions at 37°C through-out the experimental period.

A 2-way repeated-measures analysis of variance(ANOVA) was used with time as the repetition factor toevaluate the data for significant differences. As 2-wayrepeated-measures ANOVA was taking averages of allapical leakage values obtained at different time periods,1-way repeated measures ANOVA was also done toevaluate the differences in materials’ leakage with time.Multiple comparisons were done using Bonferroni pair-wise comparison test at a significance level set at � �0.05. To evaluate the significant differences in leakageof different materials at different measurement periods

dyManufacturer Batch

xy resin, Calciumments, Aerosile,um tungstate,

De Trey / Dentsply,Konstanz, Germany

0602002055

omer,nitiators; Powder:d polymerization

Sun Medical, Tokyo,Japan; Parkell Inc.,Farmingdale, NY

Powder: 060309Liquid: 051004

isGMA resins;sulphate; silica;

ines; peroxide;

SybronEndo, Orange,CA

103856

is stu

l-F epoxide pigDiamine, Calciil.

ate monphoto-iller, an

, and Bbariumith am

1-way ANOVA and Tukey HSD tests were done.

OOOOEe48 Belli et al. December 2008

RESULTSThe positive controls had grossly leaked as expected.

The varnish-coated negative controls had no measur-able bubble movement at all time periods.

The means and standard deviations of the leakagevalues of the tested materials are shown in Table II. The2-way repeated-measures ANOVA indicated that therewere no significant differences among test materials interms of fluid microleakage values (P � .126). Therewere statistically significant differences among the timeperiods since the P value is .009. To investigate whichtime periods were different in terms of mean leakagevalues, Bonferroni pairwise comparison tests were per-formed and statistically significant differences wereobserved in the 1-week and 24-week test periods (P �.005). There was significant interaction between rootcanal filling materials and test periods (P � .048). Agraph showing mean apical leakage values of the allroot canal filling materials at different time periods aregiven in Fig. 1 to show this interaction.

Results of 1-way repeated measures ANOVA andBonferroni pairwise comparison tests showed that leak-age of the AH Plus group (Group 1) decreased signif-icantly between 1- and 12-week time periods (P �.025). Leakage of the groups sealed with Hybrid RootSEAL (MetaSEAL)/Gutta Percha (Group 2) andRealSeal/Resilon (Group 4) did not change from the 1stto 24th weeks (P � 1 and P � .179 respectively). WhenHybrid Root SEAL (MetaSEAL) was used with Resi-lon (Group 3), leakage significantly decreased betweenthe 4th and 24th week measurement periods (P � .005).

Results of 1-way ANOVA and Tukey HSD testsshowed that at the first week, AH Plus group showedsignificantly more leakage than Hybrid Root SEAL(MetaSEAL)/Gutta Percha group (Group 2) (P � .025).No significant difference was obtained among materialsfor any other time period (P � .05).

DISCUSSIONTo assess the sealing ability of root fillings, several

in vitro methods have been designed and used in pre-

Table II. Apical leakage values expressed in Lp (�L/mweeks

Material period AH PlusHybrid Root(MetaSEAL

1 week 7.3 � 10�4 � 0.73 � 10�4 5.78 � 10�4 � 14 weeks 5.46 � 10�4 � 1.86 � 10�4 5.78 � 10�4 � 112 weeks 5.36 � 10�4 � 1.31 � 10�4 5.82 � 10�4 � 124 weeks 5.84 � 10�4 � 1.47 � 10�4 5.79 � 10�4 � 1

Values are means � SD (n � 10).GP, Gutta-percha; R, Resilon.

vious several investigations including dye penetration,

spectrometry of radioisotopes, fluorometric and electro-chemical methods, gas chromatography, bacterial pen-etration, and fluid transport system.36-42 Fluid filtrationmethod, in which the sealing capacity is measured bymeans of air bubble movement inside a capillary tube,was developed by Pashley’s group in 1986 to evaluatedentin permeability. The method was then modified byWu et al.33 for endodontic leakage studies. Fluid trans-port takes into account all of the porosities of theinterfaces between the filling material and tooth struc-ture. This nondestructive technique allows repeated re-producible measurements of the same specimen forlong-term evaluations.43,44 Despite it’s limitation in notproviding information about the interface location ofthe leakage, it is still the most widely used and acceptedleakage evaluation method.16,26,45-47 Thus, in thepresent study, a fluid transport model was used toevaluate leakage.

To achieve maximum apical sealing and to allowsatisfactory irrigation, a root canal preparation withtaper is necessary.48 This preparation can easily beachieved with NiTi rotary systems having various ta-pered files. After NiTi rotary preparation of the canals,

cm�2 cm H2O�1) for all test groups at 1, 4, 12, and 24

Hybrid RootSEAL(MetaSEAL)-R RealSeal

0�4 6.00 � 10�4 � 1.16 � 10�4 7.11 � 10�4 � 1.37 � 10�4

0�4 7.00 � 10�4 � 1.71 � 10�4 6.88 � 10�4 � 1.03 � 10�4

0�4 5.99 � 10�4 � 1.19 � 10�4 6.18 � 10�4 � 1.53 � 10�4

0�4 4.41 � 10�4 � 1.55 � 10�4 5.71 � 10�4 � 2.07 � 10�4

Fig. 1. Mean apical leakage values for all test groups at 4time periods.

in�1

SEAL)-GP

.20 � 1

.42 � 1

.92 � 1

.79 � 1

it is possible to fill tapered canals effectively with the

OOOOEVolume 106, Number 6 Belli et al. e49

combination of an appropriate gutta-percha cone withthe same taper. Many dental companies introducedmatching taper points that correspond to canal shapescreated by similar tapered instruments. If a round shapeis obtained during the canal preparation, an adequateobturation can be obtained with this technique49 overthe whole length of the canal faster than the lateralcondensation technique.50,51 Single-cone technique wasused in this study during the obturation of the testgroups either using a 0.04 tapered gutta-percha or Re-silon point. Other condensation groups were not in-cluded because it was not the purpose of this study tocompare the single-cone technique with other tech-niques.

Wu et al.52 reported that in single-cone filled roots,more than half of the canal space is filled with sealer.After setting, most root canal sealers have weakmatrices, and when they are subjected to oral fluids,sealer may have dissolved by that time; the single-cone fillings may contain wider voids than lateral orvertical compaction techniques.53 Furthermore, thesealer could be carried to the tooth with at most acouple of up and down strokes and this may increasesealer extrusion from the apical end when single-cone technique is used.53 In the current study, themaster cone was coated with the sealer, placed intothe canal 1 mm short of the apical foramen, androtated slowly to deliver sealer everywhere in thecanal. No extrusion of sealer was observed duringthe obturation procedure. All of the tested groupsshowed similar leakage values at the end of 24weeks. When the voids or gaps were evaluated withthe similar tested materials and single-cone tech-nique, no significant difference was found among thegroups and decreasing the sealer thickness with Re-silon or gutta-percha could not prevent gap formationin Hybrid Root SEAL (MetaSEAL) (10%) andEpiphany groups (20%).54 However, in both studies,teeth with straight roots and canals were used andwhether a good seal can be achieved with this tech-nique in curved root canals is unknown and remainsto be studied. Furthermore, human teeth were used tomore closely simulate the clinical situation. To helpreduce variability, multiple radiographs were takenfrom different directions to find similar root canalshapes. The roots having round-shape canal orificeswere selected for this purpose and classified as beinground or oval shaped according to the radiographsand root canal orifices. Each group was equally com-posed of 90% round and 10% relatively oval-shapedcanals.

Long-term sealing ability of the first epoxy-resin–based root canal sealer has been previously studied by

Wu et al.55 and AH 26 demonstrated a reduction in

leakage after storage in high humidity at 37°C for 1year. Subsequently developed AH Plus sealer showeddiminished leakage at 1 week to 12 weeks in the presentstudy, although this decrease was not significant at 24weeks. This result can either be attributed to the volu-metric increase of gutta-percha by water absorption25,55

or to the continuous expansion of AH Plus sealer withtime.30

AH Plus sealer group provided comparable sealingvalues to Hybrid Root SEAL (MetaSEAL) andRealSeal groups from the 4-week measurement periodand this could be due to the initial setting contractionand late expansion of AH Plus sealer that starts after 4weeks of its setting.30 The result of the present studyconfirmed the findings of previous researchers in thatthe quality of apical seal achieved with Resilon corematerial and Epiphany (RealSeal) sealer is not superiorto gutta-percha and AH Plus sealer.8,23 However, thesefindings are in contrast with the results reported byStratton et al.46 and Tunga and Bodrumlu.56 Discrep-ancies between these studies could be because of dif-ferences in the methodology and measurement periods.

Conventional or multistep adhesive systems may notfully infiltrate the demineralized dentin; furthermore,most of them require light-polymerization, which is notpractical for endodontic sealing. In self-etching sys-tems, demineralization of the dentin and infiltration ofmonomers may simultaneously occur. RealSeal andHybrid Root SEAL (MetaSEAL) are self-etching seal-ers having dual-curable characteristics. Although it isbelieved that this dual-curable character gives a furtheradvantage, when the results were evaluated, both seal-ers showed similar leakage values as epoxy-resin–based AH Plus sealer. This result can be explained bypolymerization shrinkage of these methacrylate-basedsealers57 following the increased sealer thickness as aresult of single cone technique58 and/or by the highc-factor inside the root canals, which was previouslyreported by Morris et al.59 and Tay et al.10 Immediatelight-curing from the coronal side of the roots may alsocreate a large polymerization stress during setting bypreventing flow of resin-based sealers and may lead tode-bonding of the resin from the root canal walls,which results in gap formation.10 The use of immediatelight curing from the coronal side used in this study wasdone according to the recommendations of the manu-facturers. The results might be different if the sealerswere left to set without any light curing.

Incomplete removal of the smear layer in isolated areasof the root canal is reported to prevent adhesive penetra-tion into the dentinal tubules.60 Structural deficienciesoriginated from the air entrapped in the sealer mass duringmixing or transferring the sealer61 may also delay the

setting reaction and weaken the resin sealer and result in

OOOOEe50 Belli et al. December 2008

de-bonding between the resin cement and the root dentinproviding an avenue for leakage.62

Onay et al.63 tested the apical sealing ability ofEpiphany-Resilon using fluid filtration method andcompared this root canal filling system with differentpairings of AH Plus, gutta-percha, Epiphany, and Re-silon. The results indicated that Epiphany–gutta-perchacombination showed less leakage than the other testgroups including AH Plus–Resilon combination andgutta-percha helped to reduce leakage when used witheither Epiphany or AH Plus. In the present study,different pairs were not retested: RealSeal was usedwith Resilon and AH Plus was used with gutta-perchafor clinical relevancy. However, the manufacturer ofHybrid Root SEAL (MetaSEAL) sealer proposed thatthis sealer can bond to both gutta-percha and Resilonpoint. Therefore, Hybrid Root SEAL (MetaSEAL) wastested with either gutta-percha or Resilon and similarleakage values were recorded and statistically no dif-ference was found between the 2 groups. This con-firmed the findings of Williams et al.64 who reportedthat Resilon and gutta-percha both demonstrate physi-cal properties of elastomeric polymers and no signifi-cant difference was found between them clinicallywhen mechanical properties of the 2 polymers wereevaluated. On the other hand, some researchers dem-onstrated that Resilon had susceptibility to alkaline andenzymatic degradation and significant weight loss andsurface thinning when compared with gutta-percha.65,66

This phenomenon may have an influence on the fluidpenetration in the long term and may need furtherevaluation.67

CONCLUSIONIn the light of our findings, we must accept the null

hypothesis that recently produced Hybrid RootSEAL (MetaSEAL) showed similar leakage perfor-mance with RealSeal and AH Plus sealers either withResilon or gutta-percha at the end of 24 weeks.However, sealing is not the only required propertyfor a root canal sealer and new sealers require furtherinvestigation into other properties essential for suc-cessful root canal treatment.

This study was supported in part by Scientific ResearchProjects Coordination Center (BAP) of SelcukUniversity, Konya, Turkey, and the leakage test wasdone in Selcuk University, Faculty of Dentistry ResearchLaboratory. The authors would like to thank SunMedical and SybronEndo companies for their generousmaterial support to this work. They are also grateful toProfessor Said Bodur and Assistant Professor Coskun

Kus for their assistance in the statistics.

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Reprint requests:

Sema Belli, DDS, PhDSelcuk UniversityFaculty of DentistryEndodontics Campus42079 KonyaTurkey

sbelli@selcuk.edu.tr