Vol. 112 No. 6 December 2011

ENDODONTOLOGY Editor: Larz S.W. Spångberg

Effectiveness of ethylenediaminetetraacetic acid (EDTA) andMTAD on debris and smear layer removal using aself-adjusting fileÖzkan Adigüzel,a Senem Yigit-Özer,a Sadullah Kaya,a Ibrahim Uysal,a

Selengül Ganidagli-Ayaz,a and Zeki Akkus,b Diyarbakir, TurkeyDICLE UNIVERSITY

Objective. The aim of this study was to investigate the cleaning ability of a self-adjusting file (SAF) system regardingdebris and smear layer removal using ethylenediaminetetraacetic acid (EDTA) or MTAD.Study design. In total, 45 maxillary incisor teeth were randomly divided into 2 different irrigation groups of 20 canalseach and a negative control group of 5 canals. The canals in each of the irrigation groups were irrigated using sodiumhypochlorite (1.3%) as an initial irrigant during the first 2 minutes of operation, followed by 2 minutes continuousirrigation with either 17% EDTA or MTAD in a closed system. The negative control group was irrigated using 1.3%sodium hypochlorite. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). Thepresence of debris and smear layer in the coronal, middle, and apical thirds of the canal was evaluated using a 5-grade scoring system with �200 and �2,000 magnification, respectively.Results. The SAF operation with 2-minute continuous irrigation using MTAD resulted in root canal walls that were freeof smear layer in 85%, 70%, and 60% and of debris in 95%, 90%, and 95% of the coronal, middle, and apical thirdsof the root canals, respectively. The SAF operation with continuous irrigation using EDTA resulted in root canal wallsthat were free of smear layer in 85%, 60%, and 50% and of debris in 95%, 90%, and 85% of the coronal, middle,and apical thirds of the root canals, respectively. Teeth in the negative control group were totally covered with debris.Evaluation by SEM showed no significant difference between the tested irrigants in removing the smear layer anddebris among the different regions of the root canal. Both groups were significantly different from the negative controlgroup.Conclusions. When using the SAF, the protocols used in this study were effective for debridement for all regions of the

root canal even for the apical thirds. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:803-808)

Successful root canal treatment is dependent on theeffective removal of bacterial biofilms and their by-products from the entire root canal system.1 Mechani-cal root canal instrumentation techniques leave a layerof organic and inorganic material known as the smearlayer, containing components such as odontoblast pro-cesses, necrotic tissue, bacteria, and their by-prod-

aDepartment of Operative Dentistry and Endodontics, Faculty ofDentistry.bDepartment of Statistical Analysis, Faculty of Medicine.Received for publication Mar. 29, 2011; returned for revision May17, 2011; accepted for publication May 21, 2011.1079-2104/$ - see front matter© 2011 Mosby, Inc. All rights reserved.

doi:10.1016/j.tripleo.2011.05.038

ucts.2,3 Because this amorphous structure prevents thepenetration of irrigants, root canal medicaments, andfilling materials into dentinal tubules, debridement isessential.4

The dual irrigation regime of sodium hypochlorite(NaOCl) and ethylenediaminetetraacetic acid (EDTA)has been used for removing the debris and smear layer,resulting in successful debridement.4 Biopure MTAD(Dentsply, Tulsa, OK), a solution of an antibiotic (tet-racycline isomer [doxycycline]), acid (citric acid), anddetergent (Tween 80), also results in effective debride-ment.5 Because chemomechanical preparation usingcurrent instrumentation techniques does not debride thetotal root canal system, because of the complexity of

root canal anatomy,6,7 irrigation solutions are manda-

803

OOOOE804 Adigüzel et al. December 2011

tory to improve root canal cleanliness.8 Different irri-gants using varying agitation techniques have beenproposed to improve the efficacy of solutions; however,conflicting results regarding the effectiveness of thesesolutions and techniques for removing smear layer anddebris have been reported.9 In a recent study by Tay etal.,10 gas entrapment prevented irrigant delivery andflow 0-2 mm from the end-point of canals, calling intoquestion the reliability of earlier studies performed withunspecified mechanisms restricting the fluid flowthrough the apical foramen.

Recently, a new nickel-titanium file system, the self-adjusting file (SAF; Redent-Nova, Ra’Anana, Israel)was developed to overcome the problems of conven-tional rotary file systems. The SAF reportedly adaptsitself 3-dimensionally to the shape of the root canal andits cross-section.11 It is attached to a special irrigationdevice (Vatea; Redent-Nova) and provides continuousirrigation during preparation via a silicon tube attachedto a rotating hub on the shaft of the file. Continuousflow of the irrigant may have positive effects on clean-ing ability, especially on the apical third of the rootcanal system, which remains a major problem.12

The present study was designed to evaluate the ef-fectiveness of 17% EDTA or MTAD on intracanalsmear layer and debris removal while using the SAF ina closed system in which 1.3% NaOCl was used as aninitial irrigant.

MATERIALS AND METHODSSelection of teeth

Forty-five human maxillary incisor teeth that hadbeen extracted for orthodontic reasons were selectedand stored in 0.1% thymol solution at 4°C until use.The age of patients was restricted to 15-20 years, be-cause the age of the teeth affects the nature of the dentinand dentinal tubules.13 Standard endodontic access cav-ity preparations were performed on the pulp chambers,and then a #15 K-type file was inserted into the canaluntil the tip was just visible at the apical foramen. Theworking length (WL) was determined at 1 mm shorterthan the canal length.

Teeth were scanned with the use of cone-beam com-puterized tomography (I-Cat; Imaging Science, Hat-field, PA), and the diameters of the teeth were measuredon the sagittal plane at the center of the coronal, middle,and apical thirds. Then teeth with similar canal anat-omy were grouped in matching pairs according to theirdiameter sizes, because the diameter of a root canalsystem may affect the efficacy of the SAF instrument.

Generating the closed systemFor the closed system, the apical foramen of each

root was covered with the use of boxing wax before

coating with hot flexible glue (Scotch Super Glue Gel;3M, St. Paul, MN) which was solidified before embed-ding the roots into a clear polyvinylsiloxane impressionmaterial (Imprint II; 3M)–filled Plexiglas tube, as sug-gested previously.10 Boxing wax was used to preventthe flow of the glue into the root canals. This totallyclosed set-up prevented irrigant extrusion from the api-cal foramen during canal preparation and provided con-tinuous irrigation.

Root canal instrumentation and irrigation withthe SAF

Teeth with matching diameters were divided into 2experimental groups, each containing 20 teeth, and 1negative control group of 5 teeth. In group 1 (EDTAgroup), 1.3% NaOCl � 17% EDTA was used, and ingroup 2 (MTAD group) 1.3% NaOCl � MTAD wasused as an irrigant and chelating agent throughout the4-minute operation using the SAF.

A glide path was established by manual instrumen-tation up to a size 20-K file, as suggested previously11;however, apical gauging with increasing sizes of Pro-Taper hand files (Dentsply-Maillefer, Ballaigues, Swit-zerland) revealed apical sizes to be #30 or #35 for themaxillary incisors, which rendered meaningless the size#20 used during manual instrumentation.

The SAF was operated using an in-and-out vibratinghandpiece, as described by Metzger et al.11 and Peterset al.14 at 5,000 vibrations/min and a 0.4-mm ampli-tude, using an irrigation device (Vatea) until it reachedthe predetermined WL. All roots were prepared by 1operator (A.Ö.) in the following sequences:

● EDTA group: The SAF file was used in 2 cycles of2 minutes each (total 4 min). NaOCl was used as theirrigant during the first cycle, and 17% EDTA duringthe second cycle.

● MTAD group: The SAF file was used in 2 cycles of2 minutes each (total 4 min). NaOCl was used as theirrigant during the first cycle, and MTAD during thesecond cycle.

● Negative control group: The SAF file was used for 4minutes using only 1.3% NaOCl.

The flow rate of the irrigants was set at 5 mL/min,resulting in a total volume of 10 mL of each finalirrigant solution. After completion of the 2 cycles, afinal rinse using 10 mL distilled water was deliveredwith a 30-G Max-I-Probe needle (Dentsply, Surrey,U.K.) to 1 mm short of the WL. The root canal wasdried using paper points, and the tooth was left to dry atroom temperature for 24 hours before being prepared

for scanning electron microscopy (SEM) examination.

OOOOEVolume 112, Number 6 Adigüzel et al. 805

SEM evaluationAccess openings were sealed to prevent debris from

getting into the canal using a temporary filling material(Cavit G; 3M Espe, Seefeld, Germany). The roots werethen split longitudinally in a buccolingual directionwith the use of a diamond disk, avoiding penetration ofthe canal. For each specimen, the half containing themost visible part of the apex was conserved and coded.Coded specimens were mounted on metallic stubs,gold-sputtered, and examined independently by 2 ob-servers using SEM (Leo Stereoscan S440; Leica, Wet-zlar, Germany).

After general evaluation of the canal wall, 3 SEMphotomicrographs were taken at magnifications of�2,000 for smear layer and �200 for debris at thecenter of the coronal, middle, and apical thirds of eachspecimen. Cleanliness was evaluated by the 5-pointscoring system introduced by Hülsmann et al.4 Thepresence of smear layer was scored as: score 1: nosmear layer, all dentinal tubules open; score 2: smallamount of smear layer, some dentinal tubules open;score 3: homogenous smear layer covering the rootcanal wall, few dentinal tubules open; score 4: com-plete root canal wall covered by a homogeneous smearlayer, no open dentinal tubules; and score 5: heavyhomogeneous smear layer covering the complete rootcanal wall.

The presence of debris was defined as dentin chips,pulp remnants, and particles loosely attached to the rootcanal wall and evaluated from images at �200 magni-fication by a 5-score system4: score 1: clean root canalwall, few small debris particles; score 2: few smallagglomerations of debris; score 3: many agglomera-tions of debris covering �50% of the root canal wall;score 4: �50% of the root canal walls covered withdebris; and score 5: complete or nearly complete rootcanal wall coverage with debris.

All results were then grouped into “clean canal wall”(scores 1 and 2) or “smear layer and debris present”(scores 3-5). Two examiners independently scored eachimage, which were coded and randomly mixed so thatthe examiners were blinded to the area from which agiven sample originated. When the examiners indepen-dently agreed on a score, it was recorded. When dis-agreement occurred, they discussed the sample and itsscoring, and an agreed score was reached.

Statistical analysisIntra- and interexaminer reliability for the SEM as-

sessment was verified by the kappa test. The data wereevaluated statistically with Fisher exact and the �2 testwith Yate correction using a 5% level of significance.Differences were considered to be significant if P �

.05.

RESULTSKappa test results showed 88% and 84% for smear

layer and debris scores for interexaminer agreement,respectively, and 96% for intraexaminer agreement.

The residual debris and smear layer SEM results ofthe root canal walls are summarized in Table I and Figs.1 and 2.

DebrisIn removing debris, 120 samples at coronal, middle,

and apical thirds had a score of 1 and 2 for 38, 36, and38 samples, respectively, for MTAD. Similarly, of 120samples, 38, 36, and 34 had a score of 1 and 2 forEDTA (Table I). The distribution of debris scores at thecoronal, middle, and apical thirds is illustrated in Fig. 2.No significant difference among the groups or betweenthe thirds was detected (P � .05) except for the nega-tive control group.

Smear layerOverall, most samples showed clean root canal sur-

faces, with high numbers of scores 1 and 2 (Fig. 1, Band C). In removing smear layer, 120 samples at cor-onal, middle, and apical thirds had a score of 1 and 2 for34, 28, and 24 samples, respectively, for MTAD. Sim-ilarly, of 120 samples, 34, 24, and 20 samples had ascore of 1 and 2 for EDTA (Table I). The distributionof smear layer scores at the coronal, middle, and apicalthirds is presented in Fig. 2. Apart from the negativecontrol, all root canal thirds had similar scores (P �.05).

DISCUSSIONThe success, reliability, and longevity of endodontic

Table I. Results of scanning electron microscopicevaluation of remaining debris and smear layer regard-ing coronal, middle, and apical thirds

Score

MTAD EDTA

Coronal Middle Apical Coronal Middle Apical

Debris1 28 22 22 26 20 222 10 14 16 12 16 123 2 4 2 2 4 44 0 0 0 0 0 25 0 0 0 0 0 0n 40 40 40 40 40 40

Smear layer1 24 20 16 20 16 62 10 8 8 14 8 143 2 6 8 4 6 104 4 4 4 2 6 65 0 2 4 0 4 4n 40 40 40 40 40 40

treatments is affected by endodontic files, rotary instru-

3-5 (de

OOOOE806 Adigüzel et al. December 2011

mentation, irrigants, and chelating agents.9 Neverthe-less, controversy exists regarding the effectiveness ofthe file systems, irrigation techniques, irrigation solu-tions, chelating agents, and evaluation methods.

During in vivo root canal preparation and irrigation,the root is enclosed by the bone socket and the canalbehaves as a closed-end channel, resulting in gas en-trapment because its closed end produces a vapor lockeffect during irrigant delivery.10 Tay et al.10 reported adifference between closed and open root canal systemsin smear layer and debris removal, and the apical vaporlock had adverse effects on debridement efficacy. Theysuggested that studies with unspecified mechanisms of

Fig. 1. A, Smear layer in a root canal treated with the SAF filelayer was present in the middle and apical portions of the rooSAF and MTAD: middle and apical thirds of the root canal.middle third of the root canal received a score of 1 using thea score of 2.

Fig. 2. Distribution of debris and smear layer scores at coronfor graphic illustration: scores 1-2 (clean canal wall) versus

restricting fluid flow through the apical foramen must

be interpreted with caution. Conflicting results in pre-viously published studies may be due to this apicalvapor lock effect. Therefore, in the present study, aclosed system was generated, as suggested byTay et al.10

For many years, the alternating use of NaOCl andEDTA has been recommended for efficient debride-ment.15-17 Similar to this dual-irrigation regime, initialrinsing of instrumented root canals with dilute NaOClwas recommended to enhance the efficacy of MTAD indissolving the smear layer.17 However, most of thosestudies report that these irrigants and chelating agentsare ineffective, especially in the apical third.18,19 Man-

aOCl alone. When NaOCl was used as the irrigant, the smear. B, The smear layer–free surface in a root canal treated withepresentative case from the experimental EDTA group. The

layer scoring system of Hülsmann et al.4; the apical third had

, middle (M), and apical (A) levels. Data were dichotomizedbris and smear layer present).

and Nt canalC, A r

smear

al (C)

cini et al.19 reported that application of MTAD and

OOOOEVolume 112, Number 6 Adigüzel et al. 807

17% EDTA for 1 minute followed by 3 mL 5.25%NaOCl was insufficient for complete removal of thesmear layer, especially in the apical third with a 30-Gnickel-titanium needle that penetrated to within 1-2 mmof the WL. Similarly, Felippe et al.18 evaluated theefficacy of doxycycline (DOX) alone or in associationwith NaOCl on intracanal smear layer removal using a27-G blunt-end needle 2 mm short of the WL andcompared this effect with EDTA associated withNaOCl, concluding that the use of NaOCl after DOXwas partially effective in removing the smear layer inthe cervical and middle thirds, but ineffective in theapical thirds. Their SEM evaluation showed that DOXwas more successful in the apical third when usedalone; however, dentinal tubules were partially filledwith a deposit and the dentin surface was covered by asmear layer when NaOCl was used after DOX appli-cation. Because of the findings of Felippe et al.,18 onlydistilled water was used after MTAD and EDTA toremove the remnants of those solutions in the presentstudy.

The SAF is a newly developed file system inendodontics. When it is inserted into a root canal, itreportedly adapts itself to the canal’s originalshape.11,14,20,21,22 The surface of the lattice isslightly abrasive, and the system removes dentinwith a back-and-forth grinding motion with vibra-tion. Importantly, the SAF reportedly allows contin-uous irrigation during the preparation. An irrigationdevice (Vatea) is connected to the silicon tube andprovides continuous flow of the preferred irrigationsolution. According to the manufacturer, this motioncreates turbulence in the root canal, allowing forcontinuous and fresh irrigant to be present in thecanal.21 Gu et al.23 stated that the continuous flow ofirrigation solution with the vibrating motion mayhave positive effects on cleaning ability, especiallythrough the cul-de-sac region and the apical third ofthe root canal system, which are difficult to clean.

Although several studies indicate that achieving totaldebridement through the entire root canal is difficult, ifnot impossible, the use of the SAF in combination witha dual-irrigation regime of 3% NaOCl and 17% EDTAhas been reported to result in clean dentin surfaces,especially in the apical portion of most root canals.21,24

Metzger et al.21 demonstrated 65% of the root canalwall free of smear layer for the apical thirds of straightroot canals. Similarly, Yigit Özer et al.24 reported 64%of the root canal wall with smear layer scores 1 and 2for the apical thirds of curved root canals in maxillarymolar teeth. In the present study, regarding the apicalthirds, smear layer removal was 60% for MTAD and50% for EDTA, with increased smear layer compared

with earlier reports using the SAF system. Probably,

apical vapor lock due to the closed system had adverseeffects on debridement efficacy.

When evaluating the removal of debris and smearlayer, the role of apical instrumentation should be con-sidered as well. Research has shown that root canalsystems need to be prepared sufficiently to removedebris and to allow proper irrigation to the apical thirdof the canal. Preparation to at least #35-#40 for ade-quate irrigation to reach the most critical apical third isessential.25 Tan and Messer26 compared hand versusrotary files using specific criteria for apical enlarge-ment. They concluded that larger instrumentation wasbeneficial in reducing the debris in the apical third ofthe canal. Recently, Usman et al.27 also showed thatlarger instrumentation files cleaned the apical third ofthe canal better than smaller instrument size.

In a recent study by Peters et al.,14 dentin removalability of SAF was evaluated on maxillary incisorsusing an SAF with 1.5-mm or 2.0-mm diameter whichhad not yet been sold in the dental market. According tothe results, preparation of straight root canals in max-illary incisors left little canal surface uninstrumentedafter shaping with the SAF. After using the 2.0-mmSAF for 5 minutes, more dentin in volume (16.43 �3.64 mm3) was reported to be removed compared withthe 1.5-mm SAF used for 6 minutes (13.58 � 3.85mm3). In the present study, a majority of the specimenswere gauged at apical sizes to #30 or #35, and moredebris and smear layer could have been removed usingthe larger diameters of SAF system; however, theywere still not being sold in the dental market.

In the present study, smear layer removal from theroot canal walls was 85% for coronal, 70% for middle,and 60% for apical thirds using MTAD. EDTA resultsfor smear layer removal were 85%, 60%, and 50% forcoronal, middle, and apical thirds, respectively. Be-cause no significant difference was observed statisti-cally among all thirds of root canals, one may assumethat effective debridement, especially in the apicalthird, may be due to the regular replenishment and largevolumes of NaOCl. During SAF operation with contin-uous irrigation, one should consider that NaOCl isrefreshed every second, making it possible for suffi-cient free chlorine to be present in the root canal todissolve the organic component of dentin debris. Ad-ditionally, the vibrating motion of the system may havepositive effects on debridement, as suggested by Gu etal.23 Successful removal of the smear layer for bothEDTA and MTAD through the entire root may be dueto the vibrating motion of the SAF within the continu-ously replaced fluid. Also, as recently suggested byDe-Deus et al.,28 the SAF system vibrating at 5,000vibrations/min induces sonic activation of the chosen

irrigant throughout the procedure. The effective de-

OOOOE808 Adigüzel et al. December 2011

bridement for both irrigants among all regions of theroot canal may also be positively affected by the sonicactivation.

CONCLUSIONWithin the limitations of this study in a closed sys-

tem, 17% EDTA and MTAD resulted in almost equallyefficient debridement in all thirds of the root canalsystem using the SAF when continuous irrigation wasperformed. Debridement in the apical thirds was assuccessful as in the coronal and middle thirds for bothirrigation solutions.

REFERENCES1. Estrela C, Sydney GB, Figueiredo JA, Estrela CR. Antibacterial

efficacy of intracanal medicaments on bacterial biofilm: a criticalreview. J Appl Oral Sci 2009;17:1-7.

2. Ricucci D, Siqueira JF Jr. Fate of the tissue in lateral canals andapical ramifications in response to pathologic conditions andtreatment procedures. J Endod 2010;36:1-15.

3. Violich DR, Chandler NP. The smear layer in endodontics—areview. Int Endod J 2010;43:2-15.

4. Hülsmann M, Rümmelin C, Schäfers F. Root canal cleanlinessafter preparation with different endodontic handpieces and handinstruments: a comparative SEM investigation. J Endod1997;23:301-6.

5. Torabinejad M, Khademi AA, Babagoli J, Cho Y, Johnson WB,Bozhilov K, et al. A new solution for removal of the smear layer.J Endod 2003;29:170-5.

6. Wu MK, Wesselink PR. A primary observation on the prepara-tion and obturation of oval canals. Int Endod J 2001;34:137-41.

7. Zmener O, Pameijer CH, Banegas G. Effectiveness in cleaningoval-shaped root canals using Anatomic Endodontic Technol-ogy, ProFile and manual instrumentation: a scanning electronmicroscopic study. Int Endod J 2005;38:356-63.

8. Gutarts R, Nusstein J, Reader A, Beck M. In vivo debridementefficacy of ultrasonic irrigation following hand-rotary instrumen-tation in human mandibular molars. J Endod 2005;31:166-70.

9. Zehnder M. Root canal irrigants. J Endod 2006;32:389-98.10. Tay FR, Gu LS, Schoeffel JG, Wimmer C, Susin L, Zhang K,

et al. Effect of vapor lock on root canal debridement using a side-vented needle for positive-pressure irrigant delivery. J Endod2010;36:745-50.

11. Metzger Z, Teperovich E, Zary R, Cohen R, Hof R. The selfadjusting file (SAF). Part 1: respecting the root canal anatomy; anew concept of endodontic files and its implementation. J Endod2010;36:679-90.

12. Estrela C, Estrela CRA, Barbin EL, Spanó JC, Marchesan MA,Pécora JD. Mechanism of action of sodium hypochlorite. BrazDent J 2002;13:113-7.

13. Fernandes A, Dessai G. Factors affecting the the fracture resis-tance of post-core reconstructed teeth: a review. Int J Prosthod2001;14:355-63.

14. Peters OA, Boessler C, Paque F. Root canal preparation with a

novel nickel-titanium instrument evaluated with micro-computed

tomography: canal surface preparation over time. J Endod2010;36:1068-72.

15. Teixeira CS, Felippe MC, Felippe WT. The effect of applicationtime of EDTA and NaOCl on intracanal smear layer removal: anSEM analysis. Int Endod J 2005;38:285-90.

16. Mello I, Robazza CRC, Antoniazzi JH, Coil J. Influence ofdifferent volumes of EDTA for final rinse on smear layer re-moval. Oral Surg Oral Med Oral Pathol Oral Radiol Endod2008;106:e40-3.

17. Torabinejad M, Cho Y, Khademi AA, Bakland LK, ShabahangS. The effect of various concentrations of sodium hypochloriteon the ability of MTAD to remove the smear layer. J Endod2003;29:233-9.

18. Felippe MCS, Moresco CV, Stolf SC, Felippe WT. Removal ofintracanal smear layer by doxycycline: SEM analysis. AustEndod J 2010;36:64-9.

19. Mancini M, Armellin E, Casaglia A, Cerroni L, Cianconi L. Acomparative study of smear layer removal and erosion in apicalintraradicular dentine with three irrigating solutions: a scanningelectron microscopy evaluation. J Endod 2009;35:900-3.

20. Metzger Z, Bassarani B, Goodis H. Instruments, materials anddevices. In: Cohen S, Hargreaves K, editors. Cohen’s pathwaysof the pulp. Philadelphia: Elsevier; 2010; pp 236-238.

21. Metzger Z, Teperovich E, Cohen R, Zary R, Paqué F, HülsmannM. The self adjusting file (SAF). Part 3: removal of debris andsmear layer. A scanning electron microscope study. J Endod2010;36:697-702.

22. Adıgüzel Ö. A literature review of self-adjusting file. Int DentRes 2011;1:18-25.

23. Gu L, Kim JR, Choi KK, Choi KK, Pashley DH, Tay FR. Reviewof contemporary irrigant agitation techniques and devices. JEndod 2009;35:791-804.

24. Yigit ÖS, Adıgüzel Ö, Kaya S. Removal of debris and smearlayer in curved root canals using self-adjusting file with differentoperation times—a scanning electron microscope study. Int DentRes 2011;1:1-6.

25. Salzgeber RM, Brilliant JD. An in vivo evaluation of the pene-tration of an irrigating solution in root canals. J Endod1977;3:394-8.

26. Tan B, Messer H. The quality of apical canal preparation usinghand and rotary instruments with specific criteria for enlargementbased on initial apical file size. J Endod 2002;28:658-64.

27. Usman N, Baumgartner JC, Marshall JG. Influence of instrumentsize on root canal debridement. J Endod 2004;30:110-2.

28. De-Deus G, Souza EM, Barino B, Maia J, Zamolyi RQ, Reis C,et al. The self-adjusting file optimizes debridement quality inoval-shaped root canals. J Endod 2011 in press.

Reprint requests:

Senem Yigit ÖzerDepartment of Operative Dentistry and EndodonticsFaculty of DentistryDicle University21280, DiyarbakirTurkey

senemygt@hotmail.com