Vol. 111 No. 1 January 2011

ENDODONTOLOGY Editor: Larz S.W. Spångberg

Effect of low-surface-tension EDTA solutions on the wettabilityof root canal dentinZeliha Yılmaz, PhD,a Berna Basbag, DDS,b Hatice Dogan Buzoglu, DDS, PhD,a andMenemse Gümüsderelioglu, DDS, PhD,bAnkara, TurkeyHACETTEPE UNIVERSITY

Objective. This study was conducted to evaluate the effect of reducing the surface tension ofethylenediaminetetraacetic acid (EDTA) solutions on the wettability of root canal dentin.Study design. Forty-two extracted teeth were sectioned at the crown, and the apical third and remaining mid-rootportion was bisected longitudinally. The root halves were embedded in resin blocks. The experimental groups weretreated with 17% EDTA, EDTA-T, and REDTA alone or followed by 2.5% NaOCl. Surface free energies of sampleswere calculated by measuring contact angles. Surface tension measurements of all solutions were performed withpendant drop method.Results. The addition of surfactant to the EDTA solution significantly decreased the surface tension of solutions (P �.01). Combined and single use of experimental solutions and NaOCl significantly decreased the water contact angleand increased the surface free energy of root canal dentin (P � .05). EDTA-T alone or combined with NaOCl alsoincreased surface free energy compared with EDTA solution (P � .05).Conclusions. The use of low-surface-tensioned EDTA compounds alone or in combination with NaOCl increased the

wettability of root canal dentin. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:109-114)

Adhesive characteristics of a surface are improved byincreasing its wetting ability.1,2 It was reported thatsurface free energy of a solid and surface tension of aliquid are major factors that affect the wetting of asolid.3,4 The surface free energy is an evaluation of thereactivity of surface or adhesiveness to its environment,and it can be determined by measuring the contactangle which is formed between a drop of the liquid andthe plane surface of the solid on which it rests. There isan inverse relation between water contact angle andsurface free energy, i.e., the lower the water contactangle, the greater the surface free energy and thereforethe greater the adhesion.5,6

The presence of a smear layer created during rootcanal preparation has an adverse effect on the penetra-

aDepartment of Endodontics, Faculty of Dentistry.bChemical Engineering Department, Faculty of Engineering.Received for publication Mar 14, 2010; returned for revision Jul 28,2010; accepted for publication Aug 4, 2010.1079-2104/$ - see front matter© 2011 Mosby, Inc. All rights reserved.

doi:10.1016/j.tripleo.2010.08.008

tion of the irrigating solution and the sealers to thedentinal tubules.7 Removing the smear layer from theroot canal by chelating agents, such as ethylenediami-netetraacetic acid (EDTA) have been suggested forbetter dentinal tubule penetration of root canal sealersto the dentinal walls as well as demineralizing andsoftening of the root canal dentin.8,9

To increase the cleaning and bactericidal potential ofthe EDTA solution, surfactant is added to it. Thisaddition reduces the surface tension of the irrigant,facilitates the wetting of the entire root canal wall andthereby increases the ability of the chelators to pene-trate to the dentin.8 For this purpose cetrimide andsodium lauryl ether sulfate are usually added toEDTA.8,10,11 It was reported that the addition of asurfactant to the EDTA solution demonstrated effec-tiveness similar to plain EDTA in smear layer removaland Ca2� ion–releasing12 or weaker chelating agents,depending on different experimental methods.11,13

However, these agents showed enhanced bactericidaleffectiveness and may lead to improved clinical perfor-

mance.14

109

OOOOE110 Yılmaz et al. January 2011

In a recent study, the addition of surfactant to theEDTA solution reduced its surface tension by �50%.15

The root canal irrigants should have very low surfacetension for good capillary penetration. Reducing sur-face tension of endodontic solutions might improvetheir dentin wetting ability and therefore the adhesiveproperties of root dentin surfaces.15,16 It was reportedthat plain EDTA decreased the wettability of den-tin.1,2,17,18 In contrast, Iwanami et al.19 reported thatsurfactant-added EDTA solution increased the spread-ing ability of solution over the dentin surface. There islimited knowledge related to the effect of detergent-added chelating agents on the wettability of root dentin.The present study was therefore planned to evaluate theeffect of reducing surface tension of EDTA solutionson the wettability of root canal dentin when they areused in combination with NaOCl.

MATERIAL AND METHODSSample preparation

The Ethical Committee of Hacettepe University ap-proved the collection and use of extracted teeth for thisstudy. Forty-two freshly extracted single-rooted humanteeth were immediately placed in saline solution at 4°Cafter debridement of surrounding soft tissue and debris.The crowns and two-thirds of the apical teeth wereremoved, and the remaining roots were split longitudi-nally into 2 equal segments with a diamond disk rotaryat low speed under coolant water. The sectioned sur-faces of 84 obtained root halves were fixed in acrylicresin blocks, with the root canal dentin surface facingup. The surfaces were polished under running water byusing 80-, 100-, 120-, 150-, and 180-grit ID siliconcarbide abrasive papers to obtain standard surfaceroughness. Thereafter, the test objects were washed inan ultrasonic water bath. Surface roughness of eachdentin surface was measured with a contact profilome-ter (SJ-400; Mitutoyo, Suzhou, China). The sampleswith similar surface roughness were included in thestudy. All samples’ surfaces were submerged in deion-ized water before contact angle measurement.

Sample treatmentThe root samples were randomly assigned to 7 exper-

imental groups (n � 6). One half of each root sample wasused for control measurement without any treatment. Theexperimental groups were designed according to the typeof irrigant as follows: group 1: 17% EDTA (Sigma-Al-drich, Munich, Germany; pH 7.4); group 2: 17% EDTA� 2.5% NaOCl (Procter & Gamble, Istanbul, Turkey);group 3: EDTA-T (17% EDTA � 1.25% sodium laurylethersulfate [Sigma-Aldrich]); group 4: EDTA-T � 2.5%NaOCl; group 5: REDTA (17% EDTA � 0.84 g cetylt-

rimethylammonium bromide [Sigma-Aldrich]); group 6:

REDTA � 2.5% NaOCl; and group 7: 2.5% NaOCl. Thetest solutions were freshly prepared in laboratory condi-tions by using deionized water. Root dentin surfaces wereirrigated with 10 mL of each irrigant for 3 minute.

Contact angle measurementsAfter treatment, dentin surfaces of experimental and

control groups were irrigated with deionized water anddried with paper points. A drop shape analysis system(DSA100; Krüss, Hamburg, Germany) was used tomeasure the contact angle from top-view images ofsessile drop when they have a flat profile. Contact anglemeasurements were achieved at 22°C by using deion-ized water, diiodomethane (Sigma-Aldrich) and ethyl-ene glycol (BDH Chemicals, Poole, Dorset, U.K.). Adrop with 0.5 �L volume of tested liquid was carefullyplaced with a micropipette on each dentin surface. Eachtime, 3 measurements were performed on different lo-cations of each sample surface, considering the surfacetreatments as independent.

Surface free energy calculationsFree energies of dentin surfaces before and after

treatments were calculated by Lifshitz–van der Waalsacid–base model, which is expressed as follows.20

(1 � cos�)�LTOT � 2��S

D�LD�0.5

� 2(�L��S

�)0.5 � 2(�S��L

�)0.5

(1)

where � is the contact angle of liquid drop on the dentinsurface, �L

TOT refers to the liquid’s surface tension, �S

is the surface free energy of solid to be determined,superscript “D” labels the dispersive component, �S

� isthe Lewis acid, and �S

� is the Lewis base component.The surface free energy of a solid can be written as

�STOT � �S

D � �SP (2)

where superscript “P” labels the polar component.The �S

P component of Equation 2 subdivides intoLewis acid (�S

�) and Lewis base (�S�) components, such

that

�SP � 2(�S

��S�)0.5 (3)

Here we used water and ethylene glycol as polar liquidsand diiodomethane as nonpolar.

If one of the 3 liquids is nonpolar (i.e., �L� �

�L� � 0) Equation 1 simplifies to

(1 � cos�)�LTOT � 2��S

D�LD�0.5 (4)

For a liquid of known surface tension Equation 4 canreadily be solved for �S

D.Here, we used following values of surface tension

parameters for water: �LTOT � 72.80 mN/m, �L

P �

51.00 mN/m, and �L

D � 21.80 mN/m; for diiodometh-

OOOOEVolume 111, Number 1 Yılmaz et al. 111

ane: �LTOT � 50.80 mN/m, �L

P � 1.30 mN/m, and�L

D � 49.50 mN/m; and for ethylene glycol: �LTOT �

48.00 mN/m, �LP � 19.00 mN/m, and �L

D � 29.00mN/m.

Surface tension measurementsThe surface tensions of test solutions were measured

at room temperature with pendant drop technique usinga drop shape analysis system (DSA100). This instru-ment provides a computer-controlled display videocamera to take pictures and an electronic syringe unit toinject samples, and thus the surface tension of thesamples could be determined quickly. When a drop ofliquid hangs from a syringe needle, a curve fittingprogram compares the experimental drop profile withtheoretically calculated profiles according to theLaplace equation:

�p � �� 1

r1

�1

r2� (5)

Equation 5 links the difference in pressure, �p, belowand above a curved section of the surface of a drop withthe principle radii of curvature r1 and r2. The interfacialtension has linear dependency on the density differencebetween the pendant drop and the surrounding medium.Therefore, an accurate knowledge of the density at themeasurement temperature is necessary.

Statistical analysesThe differences between pre- and posttreatment val-

ues were statistically analyzed by paired t test. Differ-ences among the experimental groups were analyzedusing 1-way analysis of variance (ANOVA) followedby Tukey honestly significant difference (HSD) test forpair-wise comparison at a 95% level of significance.

RESULTSThe mean value of surface roughness in root dentin

Table I. Mean contact angles and surface free energyand EDTA-T alone and combined with NaOCl (mean

Group

Contact angle values (degrees)

Water Diiodomethane

a b a b

1 59.4 16 48.7 11.3 50.1 5.0 53.9 4.9 41.2 76.1 5.4 35.6 9.4 44.5 5.5 54.7 5.7 40.3 80.5 8.8 34.7 12.5 42.0 4.9 56.0 7.7 47.4 83.2 16.0 36.7 9.8 50.1 5.9 48.0 4.5 48.5 66.8 3.9 40.3 9.9 43.2 7.7 54.7 5.6 40.6 77.9 10.4 37.6 6.6 51.9 9.1 60.7 4.5 48.7 71.3 5.8 55.0 8.8 46.8 3.7 51.4 4.2 39.

a, Before treatment; b, after treatment.

was measured as 0.60 0.25 �m. The mean contact

angles of 3 liquids and surface free energy values ofroot dentin surfaces treated with EDTA, REDTA, andEDTA-T alone or combined with NaOCl are presentedin Table I, and the percentages of posttreatment alter-ations in surface free energy levels following treatmentwith experimental solutions are also shown in Fig. 1.The statistical comparison of pre- and posttreatmentvalues by paired t test demonstrated that treatment withall chelating agents and NaOCl of root dentin surfacessignificantly increased the surface free energy levelscompared with intact control (P � .01). Thereafter, thedifferences between pre- and posttreatment values ofsurface free energy were calculated as percentage al-teration and analyzed by 1-way ANOVA. The resultsrevealed that there was a significant differences amongthe experimental groups (P � .001). Pair-wise compar-ison of experimental groups, as shown in Table II, wasanalyzed by Tukey HSD test. The results demonstratedthat EDTA-T � NaOCl treatment significantly in-creased the surface free energy of root dentin surfacewhen compared with the other experimental groups(P � .001). Single use of EDTA-T solution also sig-nificantly increased the surface free energy values ofroot canal dentin compared with the single use ofEDTA solution (P � .01). Moreover, using NaOCl as afinal flash following EDTA solutions, significantly in-creased the surface free energy values only afterEDTA-T treatment (P � .001).

The mean surface tension values of experimentalirrigants are presented in Table III. One-way ANOVArevealed significant differences among the surface ten-sions of the irrigation solutions used in the experimen-tal groups (P � .001). Pair-wise comparison of exper-imental groups by Tukey HSD test demonstrated thatincorporation of wetting agents into the EDTA solu-tions reduced their surface tension significantly (P �.001). However, NaOCl generated a result similar to

s of root dentin surfaces treated with EDTA, REDTA,)

Surface free energy(mN/m)

Surface roughness(�m)ene glycol

b a b a b

41.3 9.3 59.2 5.2 61.6 6.1 0.6 0.2 0.5 0.156.6 7.6 55.3 2.2 61.0 5.1 0.5 0.1 0.7 0.249.3 10.0 52.5 6.8 62.7 8.3 0.6 0.3 0.5 0.146.8 5.1 47.5 1.7 66.2 9.9 0.6 0.2 0.4 0.139.9 5.1 58.1 2.1 65.0 4.1 0.6 0.2 0.6 0.238.0 5.0 53.2 2.0 63.0 2.2 0.8 0.2 0.8 0.338.2 4.5 56.5 2.0 61.79 3.2 0.5 0.1 0.5 0.2

value SD

Ethyl

a

5 3.09 2.64 9.69 8.34 5.35 5.16 3.2

deionized water and EDTA.

OOOOE112 Yılmaz et al. January 2011

DISCUSSIONSurface tension is defined as a condition of intramo-

lecular attraction on the surface of a liquid in contactwith a solid tending to pull the molecules inward fromthat surface. When this intramolecular attraction is de-stroyed, the surface tension decreases. This might beachieved by using heat or adding a surfactant.21,22 Inthe present study, it was discovered that the surfacetension levels of NaOCl and EDTA were similar to thewater surface tension. These data corroborate the re-sults of Zehnder et al.12 In the literature, however,significantly lower surface tension values for EDTAand NaOCl than water have also been reported.15,21,23

These differences might result from preparation andstorage conditions of EDTA solutions. In the presentstudy, EDTA solution was freshly prepared using diso-dium EDTA and deionized water.

A low surface tension should increase the penetrationof the mixture into the dentinal tubules and even intothe uninstrumented areas, reducing the bacterial con-tamination of the root canal system.15,22 EDTA fails inits antibacterial action,24 and the addition of detergentmight improve its antibacterial effectiveness as well asincreasing the ability to penetrate deeper into the den-tin, which might thus enhance its clinical perfor-mance.8,21 It was reported that to achieve optimal wet-tability, the surface energy of the substrate must be ashigh as possible and the surface tension of the liquidcontacted with substrate must be as low as possible.1,25

In the present study, the results seem to support thishypothesis. EDTA-T and REDTA demonstrated signif-icantly lower surface tension levels and they improvedthe wettability of root canal surfaces. However, the

Fig. 1. Percentage alteration of surface free energy (SFE)values of dentin surfaces following treatment with experi-mental solutions.

results were statistically significant only for EDTA-T

solution. Moreover, using NaOCl as final flush demon-strated additional improvement in the effectiveness ofEDTA-T solution on the wettability of root dentinsurface. Sayin et al.26 reported that using chelatingagents in combination with NaOCl significantly in-creased the removal of Ca2� from root dentin. In aprevious study,17 we demonstrated that NaOCl treat-ment improved the wettability of RC-Prep, which con-tains urea peroxide, an agent with a potential to oxidizecollagen, although it did not affect the wettability ofEDTA. After NaOCl treatment, an increase in the wet-tability is expected because deprotenization leads to ahydrophilic surface.2,25,27 Moreover, NaOCl increasesthe diameter and size of open dentinal tubules of de-mineralized dentin and might cause porous area withmultiple irregularities.28 The increase in the microme-chanical retention of the dentin surface might allowbetter material penetration and good dentinal adhe-sion.7

Dentin is composed of 2 different substrates: colla-gen, which has a low surface energy, and hydroxyap-atite, which has a high surface energy.29 A decrease insurface free energy of dentin was reported after appli-cation of EDTA owing to the exposure of collagenfibers.1,2,10 In contrast, an increase was reported in thewettability of occlusal dentin surface after acid etch-ing.30-32 In the present study, EDTA treatment alone for3 minutes demonstrated a slight increase in the wetta-bility of root canal dentin surface. However, in ourprevious study,17 EDTA treatment for 15 minutes sig-nificantly decreased the surface free energy of rootcanal dentin. Calt and Serper33 suggested that extendedapplication time of dentin with EDTA might havecaused alteration on the dentin surface owing to theremoval of more Ca2� from root dentin and occurrenceof tubular erosion.

Contact angle can be measured using captive bubbleor sessile drop techniques. In the captive bubble tech-nique, the solid surface is kept in a fully hydrated state,and the surface free energy components are obtainedfrom air bubble and n-octane droplet at the sample-water interface.10 In the present study, the sessile dropmethod was used. In this method, the contact angles ofliquid drop on the flat surfaces are maintained in a dryenvironment.2,11 Although in most studies, the solidsurfaces were dried with air,20,30,31 in the present studythe samples were dried with paper point after rinsingwith deionized water to study them under conditionssimilar to the root canal environment. This might havecaused alterations in EDTA treatment groups regardingsurface free energy, because contact angle measure-ments are highly sensitive.

Moreover, Combe et al.20 reported that theoretically

only 3 liquids are needed for surface free energy cal-

OOOOEVolume 111, Number 1 Yılmaz et al. 113

culations but 3 liquids can be used to maintain con-sistent statistical results. In the present study, contactangle measurement was achieved by 3 liquids, similarlyto the study of Tani et al.,18 because root canal surfacehas very limited area to place more droplets.

Additionally, the solid surface should be clean, rigid,and highly smooth to achieve correct contact anglemeasurement,5 although the root canal dentin surfacesare not smooth after cleaning and shaping. As Iwanamiet al.19 speculated that it is very difficult to measure thecontact angle in highly smooth surfaces owing to rapidspreading. In the present study, instead of fine polish-ing, root dentin surfaces were polished with graverpaper to obtain surfaces somewhat similar to clinicalconditions, and roughnesses were measured with a pro-filometer before irrigation regimes. The mean value ofsurface roughness in root canal dentin was measured tobe 0.60 0.25 �m. Indeed, roughness makes a signif-icant contribution to the wetting behavior of a sur-face.34,35 During bonding process, free energy androughness play a key role by interacting with eachother. It is presumed that surface roughness and irreg-ularities promote wettability by producing increasedsurface area and that the bond between the adheredsurface and the adhesive will be subsequently stron-ger.31,32 In the present study, surface roughness mighthave additionally improved the wettability. However,excessive roughness might hinder even flow of theliquid adhesive and result in air pockets being inter-rupted at the interface. With the contact angle method,it is very difficult to differentiate the contribution of

Table II. Pair-wise statistical comparison of the experEDTA EDTA � NaOCl EDTA-T

EDTA — NS SEDTA � NaOCl NS — NSEDTA-T S NS —EDTA-T � NaOCl S S SREDTA NS NS NSREDTA � NaOCl S NS NSNaOCl NS NS NS

S, Statistically significant; NS, not significant.

Table III. Mean surface tension values of experimentalirrigants (mN/m; mean SD)

Irrigant Surface tension

Deionized water 72.03 0.07EDTA 69.64 0.20EDTA-T 25.33 0.02REDTA 35.86 0.10NaOCl 72.62 0.20

surface roughness to a measured surface energy.2-4

In conclusion, the present study revealed that theaddition of surfactant to the EDTA solution signifi-cantly decreased the surface tension of EDTA solutionand increased the wettability of root canal dentin sur-faces. Therefore, it is suggested that low-surface-ten-sion EDTA solutions might improve the adhesion prop-erties of root canal dentin. Because the properties of theadhesive material also are very important for a success-ful adhesion mechanism, further studies are needed toevaluate the effectiveness of both factors together.

REFERENCES1. Erickson RL. Surface interactions of dentin adhesive materials.

Oper Dent 1992;5:81-94.2. Attal JP, Asmussen E, Degrange M. Effects of surface treatment

on the free surface energy of dentin. Dent Mater 1994;10:259-64.3. Al-Omari WM, Mitchell CA, Cunningham JL. Surface rough-

ness and wettability of enamel and dentin surfaces prepared withdifferent dental burs. J Oral Rehabil 2001;28:645-50.

4. Eick JD, Johnson LN, Fromer JR, Good RJ, Neumann AW.Surface topography: its influence on wetting and adhesion in adental adhesive system. J Dent Res 1972;51:780-8.

5. Milosevic A. The influence of surface finish and in-vitro pellicleon contact-angle measurement and surface morphology of threecommercially available composite restoratives. J Oral Rehabil1992;19:85-97.

6. O’Kane C, Oliver RG, Blunden RE. Surface roughness anddroplet contact angle measurement of various orthodontic bond-ing cements. Br J Orthod 1993;20:297-305.

7. Saleh IM, Ruyter IE, Haapasalo M, Ørstavik D. The effects ofdentin pretreatment on the adhesion of root-canal sealers. IntEndod J 2002;35:859-66.

8. Hülsmann M, Heckendorff M, Lennon A. Chelating agents inroot canal treatment: mode of action and indications for their use.Int Endod J 2003;36:810-30.

9. Gulabivala K, Patel B, Evans G, Yuan-Ling Ng. Effects ofmechanical and chemical procedures on root canal surfaces.Endod Top 2005;10:103-22.

10. Goldberg F, Abramovich A. Analysis of the effect of EDTAC onthe dentinal walls of the root canal. J Endod 1977;3:101-5.

11. Scelza MF, Antoniazzi JH, Scelza P. Efficacy of final irrigation:a scanning electron microscopic evaluation. J Endod 2000;26:355-8.

12. Zehnder M, Schicht O, Sener B, Schmidlin P. Reducing surfacetension in endodontic chelator solutions has no effect on theirability to remove calcium from instrumented root canals. J Endod2005;31:590-2.

al groupsDTA-T � NaOCl REDTA REDTA � NaOCl NaOCl

S NS S NSS NS NS NSS NS NS NS— S S SS — NS NSS NS — NSS NS NS —

imentE

13. De-Deus G, Reis C, Fidel S, Fidel R, Paciornik S. Dentin

OOOOE114 Yılmaz et al. January 2011

demineralization when subjected to EDTA with or withoutvarious wetting agents: a co-site digital optical microscopystudy. Int Endod J 2008;41:279-87.

14. Guerisoli DM, Marchesan MA, Walmsley AD, Lumley PJ,Pecora JD. Evaluation of smear layer removal by EDTAC andsodium hypochlorite with ultrasonic agitation. Int Endod J2002;35:418-21.

15. Giardino L, Ambu E, Becce C, Rimondini L, Morra M. Surfacetension comparison of four common root canal irrigants and twonew irrigants containing antibiotic. J Endod 2006;32:1091-3.

16. Glantz PO, Hansson L. Wetting of dentin by some root canalmedicaments. Odontol Revy 1972;23:205-10.

17. Dogan Buzoglu H, Calt S, Gümüsderelioglu M. Evaluation of thesurface free energy on root canal dentin walls treated withchelating agents and NaOCl. Int Endod J 2007;40:18-24.

18. Tani C, Manabe A, Itoh K, Hisamitsu H, Wakumoto S. Contactangle of dentin bonding agents on the dentin surface. Dent Mater1996;15:39-44.

19. Iwanami M, Yoshioka T, Sunakawa M, Kobayashi C, Suda H.Spreading of root canal irrigants on root dentin. Aust Endod J2007;33:66-72.

20. Combe EC, Owen BA, Hodges JS. A protocol for determiningthe surface free energy of dental materials. Dent Mater2004;20:262-8.

21. Abou-Rass M, Patonai FJ Jr. The effects of decreasing surfacetension on the flow of irrigating solutions in narrow root canals.Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1982;53:524-6.

22. Cameron JA. The effect of a fluorocarbon surfactant on thesurface tension of the endodontic irrigant, sodium hypochlorite.A preliminary report. Aust Dent J 1986;31:364-8.

23. Tasman F, Cehreli ZC, Ogan C, Etikan I. Surface tension of rootcanal irrigants. J Endod 2000;26:586-7.

24. Shabahang S, Pouresmail M, Torabinejad M. In vitro antimicro-bial efficacy of MTAD and sodium hypochlorite. J Endod2003;29:450-2.

25. Ruyter IE. The chemistry of adhesive agents. Oper Dent 1992;5:32-43.

26. Sayin TC, Serper A, Cehreli ZC, Kalayci S. Calcium loss from

root canal dentin following EDTA, EGTA, EDTAC, and tetra-

cycline-HCl treatment with or without subsequent NaOClirrigation. J Endod 2007;33:581-4.

27. Panighi M, G’Sell C. Influence of calcium concentration on thedentin wettability by an adhesive. J Biomed Mater Res 1992;26:1081-9.

28. Niu W, Yoshioka T, Kobayashi C, Suda H. A scanning electronmicroscopic study of dentinal erosion by final irrigation withEDTA and NaOCl solutions. Int Endod J 2002;35:934-9.

29. Akinmade AO, Nicholson JW. Glass-ionomer cements as adhe-sives. Part I. Fundamental aspects and their clinical relevance. JMater Sci Mater Med 1993;4:95-101.

30. Toledano M, Osorio R, Perdigao J, Rosales JI, Thompson JY,Cabrerizo-Vilchez MA. Effect of acid etching and collagen re-moval on dentin wettability and roughness. J Biomed Mater Res1999;47:198-203.

31. Rosales JI, Marshall GW, Marshall SJ, Watanabe LG, ToledanoM, Cabrerizo MA, et al. Acid-etching and hydration influence ondentin roughness and wettability. J Dent Res 1999;18:1554-9.

32. Armengol V, Laboux O, Weiss P, Jean A, Hamel H. Effects ofEr:YAG and Nd:YAP laser irradiation on the surface roughnessand free surface energy of enamel and dentin: an in vitro study.Oper Dent 2003;28:67-74.

33. Calt S, Serper A. Time dependent effects of EDTA on dentinstructures. J Endod 2002;28:17-9.

34. Lee HJ, Michielsen S. Preparation of a superhydrophobic roughsurface. J Polym Sci B Polym Physiol 2007;45:253-61.

35. Cooke FW, Lemmons JE, Ratner BD. Properties of materials inmedicine. In: Hoffman AS, Ratner BD, Schoen FJ, Lemons JE,editors. Biomaterials science: an introduction to materials inmedicine. San Diego: Academic Press 1996.

Reprint requests:

Dr. Zeliha YilmazDepartment of EndodonticsFaculty of DentistryHacettepe University06100, SıhhıyeAnkara, Turkey

zeliha@hacettepe.edu.tr