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Ef f e c tofde nt i ns ur f ac er e moval ont heNaOCl -t r e at e dde nt i n

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Ef f e c tofde nt i ns ur f ac er e moval ont heNaOCl -t r e at e dde nt i n

차아염소산나트륨 용액으로 처리된 상아질 표면의 삭제 효과

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Ef f e c tofde nt i ns ur f ac er e moval ont heNaOCl -t r e at e dde nt i n

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송미연의 석사학위논문을 인준함.

위원장 조선대학교 교수 최 한 철 인 위 원 조선대학교 교수 황 호 길 인 위 원 조선대학교 교수 민 정 범 인

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TABLE LEGENDS

Table1.Materialsusedinthestudy···2

Table2.Meanmicrotensilebondstrength(MPa)todentinafterdifferent surfacetreatment···6

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FI GURE LEGENDS

Fig.1.(a)Microtensiletester(b)Beam attachedonmicrotensiledevice

···4

Fig.2.Schematicrepresentationofthespecimenpreparation.···5

Fig.3.Meanmicrotensilebondstrength(MPa)todentinafterdifferent surfacetreatment.···7

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국 문 초 록

차아염소산나트륨 용액으로 처리된 상아질 표면의 삭제 효과

송 미 연

지도교수 황호길 조선대학교 대학원 치의학과

본 연구에서는 차아염소산나트륨으로 처리된 상아질 결합강도를 높이기 위 해서 항산화제 (10% 아스코르브산)를 사용한 것과 표면 상아질을 삭제한 경 우의 효과를 비교하였다.인간 제 3대구치 20개를 사용하였으며 미세인장강 도 시험을 위해 편평한 상아질 면이 얻어지도록 법랑질을 제거하고 무작위로 4가지 군으로 분류하였다.대조군은 차아염소산나트륨의 영향을 받지 않은 군으로 0.9% 생리식염수로 10분간 처리하였다.1군은 5.25% 차아염소산나트 륨으로 10분간 처리하였다.2군은 1군과 같은 방법으로 처리한 후 10% 아스 코르브산으로 10분간 처리하였다.3군은 1군과 같은 방법으로 처리한 후 거 친 다이아몬드 버를 이용하여 0.1mm 가량 삭제하였다.모든 치아의 표면을 건조시킨 후 ClearfilSE bond를 사용하여 접착제를 도포한 후 즉시 Filtek Z250복합레진을 사용하여 수복하였다.24시간 보관 후 미세인장 결합강도를 측정하였다.실험 결과,차아염소산나트륨만 처리한 1군의 결합강도 (19.44±

4.49MPa)가 다른군들에 비해 유의적으로 낮게 나타났다 (p<0.01).10% 아 스코르브산를 처리한 2군 (31.96± 8.48MPa)이 다른 군들보다 유의적으로 높은 수준의 결합 강도를 보였다 (p<0.05).반면에 버로 상아질 표층을 삭제 한 3군 (26.08± 5.25MPa)은 대조군과 통계적으로 유의한 차이가 나타나지 않았다.결론적으로,5.25%의 차아염소산나트륨 세척은 two-step self-etch adhesive의 상아질 결합 강도를 유의적으로 감소시켰으며 10% 아스코르브산 의 사용 또는 표층 상아질 삭제는 감소된 결합강도를 회복시키는 효과가 있 었다.

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I .I nt r oduct i on

Effective cleaning and shaping ofthe rootcanal,as wellas creation ofan apicalsealis an essentialgoalforsuccessfulendodontic treatment.Recently, more attention has been focused on procedures performed to achieve an effective coronalsealing soon afterthe completion ofrootcanaltherapy.The immediatesealing ofendodontically treated teeth using restorative materials is powerfultoolin preventing early coronalleakage.^1-3 The importance of the coronalrestoration in successfulendodontic outcomes is widely accepted and has been supported by Ray and Trope.⁴ Among definite restorative materials, dentin adhesives have been advocated foruse within the pulp chamberin an attempttoworkasadurablebarrieragainstmicroleakagehamperingapicaland coronalmicroleakage.

Sodium hypochlorite (NaOCl) is the most widely recommended irrigant in endodontics because of its ability to dissolve necrotic tissue remnants.⁵ According to many articles,NaOClreduces the bond strength between resin composites and dentin.⁶^-8 This is thought to be due to remnants and by-productsofNaOClexhibiting negativeeffecton thepolymerization ofdental adhesivesystems.

Torestorethebondstrength tonormalrange,10% sodium ascorbateor10%

ascorbic acid were introduced to apply on theNaOCl-treated dentin.⁶^,⁹Weston CH etal.¹⁰recommended treatmentwith ascorbicacid orsodium ascorbatefor 10min.Butitisanimpracticalrecommendationforclinicalsituation.

Inroutineendodontictherapy,mostcliniciansremovealittleamountofpulpal walltoobtain clean dentinalsurfaceaftercanalobturation procedure.However, there was no study whether removing dentin surface after NaOCl-treatment affectsonmicrotensilebondstrengthornot.

Thepurposeofthisstudy wastocomparetheeffectofremoving superficial dentin surface with that of antioxidant (ascorbic acid) on microtensile bond strengthofsodium hypochlorite-treateddentin.

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Brand Material Composition Manufacturer

Clearfil™

SE Bond

two-step self-etch adhesive

system

Primer; MDP, HEMA, hydrophilic dimethacrylate

Bond: MDP, Bis-GMA, HEMA, hydrophilic dimethacrylate, DL-

camphorquinone,

N,N-diethanol-p-toluidine and silanated colloidal silica

Kuraray, Osaka, Japan

Filtek™

Z250

composite resin

Bis-GMA, BisEMA, UDMA, TEGDMA, Silane treated ceramic

3M ESPE, St.

Paul, MN, USA

I I .Mat er i al sandMet hods

1.Speci men pr epar at i on

Twenty non-carioushuman third molarswereused in thisstudy.Theteeth werecleaned ofperiodontaltissueresidueusing a periodontalscalerand were storedindistilledwateratroom temperature.Storagewaterwaschangeddaily.

Theocclusalenamelwasremovedby sectioning thecrownperpendiculartothe long axis ofthe tooth using a modeltrimmer (Se-ki,Seoul,Korea.) under copious waterlavage to achieve a flatsuperficialdentin surface.And dentin surface was wet-polished by abrasive paper(600 grit;Silicon Carbide Water ProofAbrasivePaperElectro Coated,Daesung,Korea)with running tap water for1mintoobtainsmoothdentinsurfaceandrinsedfor1min.

The teeth were randomly divided into four groups and each group had 5 specimens.ThematerialsusedinthestudyarelistedinTable1.

Table1.Materialsusedinthestudy.

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Thedentinsurfacetreatmentofeachgroupsareasfollows;

Control:dentin surfacewasirrigatedwith 0.9% NaClfor10min,then rinsed with10mL ofdistilledwater.

Group1:dentinsurfacewasirrigatedwith5.25% NaOCl(Yuhanclorox,Seoul, Korea)for15minpertooth,thenrinsedwith10mL ofdistilledwater.

Group 2 :after treatmentas in group 2,freshly made 10% ascorbic acid (JUNSEI,Tokyo,Japan)wasappliedtothedentinsurfacesfor10min,followed byrinsingwith10mL ofdistilledwater.

Group3:aftertreatmentasingroup2,thedentinsurfacewasremovedabout 0.1 mm with coarse diamond bur(TR 14,MANI,INC.,Utsunomiya Tochigi, Japan),thenrinsedwith10mL ofdistilledwater.

Afterpre-treatment,the specimens were dried with airsyringe,and Clearfil SE Bond(Kuraray,Osaka,Japan)asdentin adhesiveappliedtodentin surfaces following the manufacturer's instructions. Spectrum 800 (Dentsply Caulk, Milford,DE.USA)with outputintensity of400 mW/cm² was used forlight curing. Resin composites (Filtek Z250; 3M ESPE, St. Paul, MN, USA) build-ups were constructed in three 1.5 mm increments.Each incrementwas light-curedfor40s.Then thespecimenswerestoredin distilledwaterat25℃

for24h

2.Mi cr ot ensi l ebondst r engt h t est

Afterbeing stored in distilled waterat25℃ for24 h,the specimens were embedded in acrylic blocks using sticky wax (Kerrcorporation,Orange,CA, USA).Then they wereplaced on a low-speed diamond saw (Isomet;Buehler, LakeBluff,IL,USA)toproduce1mm X 1mm adhesivesurfacearea beams underwatercooling.Each beam consisted ofcomposite resin and dentin.The dimensionofeachbeam wasmeasuredusingdigitalcaliperandthebondedarea was calculated forsubsequentconversion ofmicrotensile bond strength values

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intounitsofstress(MPa).

Thebeamswereattached with cyanoacrylateadhesive(Zapit;DVA,Corona, CA, USA) to a testing apparatus and tensile load was applied with a microtensile tester(Micro Tensile Tester;Bisco,Schaumburg,IL,USA)ata cross-headspeedof0.5mm/min(Figure1).

Figure1.(a)Microtensiletester(b)Beam attachedonmicrotensiledevice.

3.St at i st i calanal ysi s

Themicrotensilebond strength datawasanalyzed forstatistically significant differencesby one-way analysisofvariance(ANOVA)and Tukey’stestusing SPSS^™ Ver 12.0 (SPSS Inc,Chicago,IL,USA).Statisticalsignificance was definedasp<0.05.

ThespecimenpreparationprocedureisschematicallyillustratedinFigure2.

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Figure2.Schematicrepresentationofthespecimenpreparation.

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Group Number Mean S.D.

Control(NaCl) 30 27.26^a 5.74

1(NaOCl) 30 19.44^b 4.49

2(Ascorbicacid) 30 31.96^c 8.48 3(Dentinremove) 30 26.09^a 5.25

I I I .Resul t s

1.Mi cr ot ensi l ebondst r engt h

Meanmicrotensilebondstrengthvaluesandstandarddeviation ofeachgroup areshowninTable2andFigure3.One-wayANOVA revealedthattherewere significant differences between surface treatment methods (p<0.001). The microtensilebond strength oftheNaOCl-treated dentin (group 1)demonstrated significantly lower bond strength than the controlgroup (p<0.01).Treatment with 10% ascorbic acid (group 2) demonstrated significantly higher bond strength than othergroups (p<0.05).There was no significantdifferences in bond strength between removalof superficialdentin surface (group 3) and controlgroup(p>0.05).

Table2.Meanmicrotensilebondstrength(MPa)todentinafterdifferent surfacetreatment

Groups identified by different superscript letters are significantly different (p<0.05).

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Figure3.Meanmicrotensilebondstrength(MPa)todentinafterdifferent surfacetreatment.

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I V.Di scussi on

Theaim ofthisstudy wastoinvestigatetheeffectofremovalofsuperficial dentinsurfacetorestorethedecreasedbondstrengthcausedbyNaOCl.

Sodium hypochlorite(NaOCl)hasbeenwidelyusedinrootcanaltreatmentto providegross debridement,disinfection,lubrication,and dissolution oftissues.¹¹ NaOClcausesalterationsin cellularmetabolism and phospholipid destruction.It has oxidative actions thatcause deactivation ofbacterialenzymes and causes lipidandfattyaciddegradation

Severalstudies have reported thatdentin thathas been exposed to NaOCl exhibitssignificantly lowerbondstrengthsthanuntreateddentin.⁶^-9,¹²Onestudy reported bond strengths as low as 8.5 MPa.⁷Increased microleakagewasalso reported.¹³ The results ofthis study showed thatNaOClirrigation generally decreasethebond strength ofself-etch adhesivetodentin.Thisresultwasin agreement with previous studies.^7,^14,¹⁵ NaOCl removes any exposed organic matrix,mainly the collagen or soft tissue from the dentin and leaves a mineralizedsurfacelessreceptivetobondingwithresincomposites.¹⁰Itislikely thatNaOClacts to oxidize a componentin thedentinalmatrix thatinterferes with free radicalpropagation atthe resin–dentin interface,leading to lower bondstrength.Inaddition,whenNaOClbreaksdown,oxygenwillbemadeand it causes strong inhibition of the interfacial polymerization of adhesive materials.¹⁶ According to Laietal.,in NaOCl-treated dentin,there mightbe somereactiveresidualfree-radicals,which mightcompetewith thepropagating vinylfree radicals generated during lightactivation ofthe adhesive system, resulting in premature chain termination and incomplete polymerization.⁹ Furthermore,reductions in calcium and phosphorus levels¹⁷and in mechanical properties of dentin, such as elastic modulus, flexural strength, and microhardness¹⁸,were reported afterirrigation ofrootcanals with 5% sodium hypochlorite,which can also contribute to a decrease in the micromechanical

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Dentin bonding is based on the formation ofa resin-infiltrated layerin the conditioned intertubular and peritubular dentin. After polymerization, resin monomersmayform amicro-mechanicalbondwiththeprimeddentin,so-called hybrid layer.¹⁹Thus,to achievesatisfactory dentin adhesion,open tubules and exposed collagen-rich meshwork should be infiltrated by resin monomers entirely and homogeneously.However,NaOCl damaged the organic matrix, mainly thecollagen.Therefore,weak hybrid layerwasformed and microtensile bondstrengthwassignificantlydecreased.

Morris etal.⁶showed thatapplication of10% ascorbic acid or10% sodium ascorbate,bothofwhichareantioxidant/reducing agents,reversedtheeffectsof sodium hypochloriteandrestoredbondstrengthstonormallevels.Laietal.and Yiu etal.also reported similarresults.^9,¹³ 10% ascorbic acid (pH=4)was as effectiveas10% sodium ascorbate(pH=7)toreversetheloweredbondstrength ofNaOCltreateddentin.⁶Inthisstudy,applicationofNaOCl-treateddentinwith 10% ascorbicacid for10min (group2)demonstrated significantly higherbond strengththanothergroups(p<0.05).By treating dentinwith10% ascorbicacid, themicro-environmentofthedentinisconvertedfrom an oxidizedsubstrateto areducedsubstrate.Itseemsthatthisredox potentialrecovery can restorethe bondstrengthtonormalrange.

Theinfluenceofendodonticirrigantson adhesion wastested with two step self-etch adhesive system. Restoration of endodontically treated teeth with self-etch adhesivesandcompositesmay offersomeadvantagesovertheuseof conventionaltotal-etchdentaladhesives.Self-etchadhesiveshaveweakacidsin their primer composition,resulting less change in the dentinalwallstructure than the strong acids oftotal-etch systems.In addition,primerapplication is performed withoutair-drying,collapse ofcollagen fibrils is avoided,reducing technique-sensitivity.²⁰Self-etching systems (ClearfilSE Bond,PromptL-pop) were more successful than one bottle (Prime&Bond NT) and multistep (ScotchbondMultiPurposePlus)inbondingtopulpchamberdentinalwalls.¹⁴So, self-etch adhesive (ClearfilSE Bond)was used as a bonding agentin this study.

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Numerous studieshavedescribed theimpactofmany antioxidantto reverse the bond strength ofthe NaOCltreated dentin.^6,¹⁰^,²¹ Butin clinicalsituation, applicationof10% ascorbicacidtopulpchamberfor10ministime-consuming.

Therefore,this study was designed to find a simple way to restore the decreased bond strength caused by NaOCl.A study abouteffectofsodium hypochlorite on human root dentin, reported that exposure to 5% NaOCl rendered the superficial80-100 ofthe intertubular dentin permeable to basic fuchsin.²²Thelossoftooth structuredecreasestooth stiffnessby only 5%.²³In fact,thelargestreduction in tooth stiffnessresultsfrom additionalpreparation, especially the loss of marginal ridges. Therefore, additional removal of superficialdentin layer about 0.1 mm withoutdestruction ofmarginalridge before bonding procedure willexposure the fresh dentin and restore the bond strengthandreducethecoronalleakage.

Thereare some limitations in this study.The microtensilebond testallows bondtestingofsmallareaspromotingabetterstressdistributionthroughoutthe specimen andinducesfailuresofmaterialsthatareclosertotheirtrueultimate strengths and aremostly adhesive failures.²⁴However,the correlation between bondstrength andmicroleakageisnotwellestablished,andbondstrength data alone are notsufficientto evaluate the sealing ability ofresins.According to this,therationaleinvolving microtensilebond testing ofendodonticsurfacesis that a better adhesion of restorative materials to dentin increases the opportunity for good marginal sealing, longer life of the restoration, and withstandingofmechanicalstresses.

Furtherresearch should focuson theoptimalamountofdentin removalafter exposure to NaOCl. Microleakage studies should also evaluate the sealing propertiesofresinovertime.Thestructureofpulpchamberwalldentin differs from thatoftheotherdentinalregionsofteeth.Additionalexperimentshouldbe done with pulp chamberwalldentin because flatocclusaldentin was used in thisstudy.

Because NaOClis likely to remain the primary irrigantused in endodontics

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restoring endodontically treated teeth,this issue willhave to be addressed.

Future adhesive resin products for endodontic applications may contain a reducing agent to reverse the effects of the sodium hypochlorite. A non-oxidizingirrigantwouldalsosolvethisproblem.

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V.Concl usi ons

Irrigation with NaOClsignificantly reduced the microtensile bond strength.

Antioxidantapplication and superficialdentin removalsignificantly restored the decreasedbondstrengthofNaOCl-treateddentin.

Withinthelimitationsofthisstudy,itisconcludedthatremovalofsuperficial dentinsurfacecouldbeusedasasimplewayofrestoring thebondstrengthto NaOCl-treateddentin.

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Ref er ences

1. BelliS,Zhang Y,Pereira PN,Pashley DH.Adhesive sealing ofthe pulp chamber.JournalofEndodontics2001;27:521-526.

2. BelliS,Zhang Y,PereiraPN,OzerF,PashleyDH.Regionalbondstrengths of adhesive resins to pulp chamber dentin. Journal of Endodontics 2001;27:527-532.

3. Galvan JrRR,WestLA,LiewehrFR,Pashley DH.Coronalmicroleakageof five materials used to create an intracoronalsealin endodontically treated teeth.JournalofEndodontics2002;28:59-61.

4. Ray H,TropeM.Periapicalstatusofendodontically treatedteethinrelation to the technical quality of the root filling and the coronal restoration.

InternationalEndodonticJournal1995;28:12-18.

5. ZehnderM.Rootcanalirrigants.JournalofEndodontics2006;32:389-398. 6. Morris MD,Lee K-W,Agee KA,BouillaguetS,Pashley DH.Effects of

sodium hypochlorite and RC-prep on bond strengths of resin cementto endodonticsurfaces.JournalofEndodontics2001;27:753-757.

7. ErdemirA,AriH,GüngüneşH,BelliS.Effectofmedicationsforrootcanal treatment on bonding to root canal dentin. Journal of Endodontics 2004;30:113-116.

8. NikaidoT,TakanoY,SasafuchiY,Burrow M,TagamiJ.Bondstrengthsto endodontically-treatedteeth.AmericanJournalofDentistry1999;12(4):177-80.

9. LaiS,Mak Y,Cheung G,OsorioR,ToledanoM,CarvalhoRl.Reversalof compromised bonding to oxidized etched dentin.JournalofDentalResearch 2001;80:1919-1924.

10.Weston CH, Ito S, Wadgaonkar B, Pashley DH. Effects of time and concentrationofsodium ascorbateonreversalofNaOCl-inducedreductionin bondstrengths.JournalofEndodontics2007;33:879-881.

11.Spangberg L,Engström B,LangelandK.Biologiceffectsofdentalmaterials: 3.Toxicity and antimicrobialeffectofendodontic antiseptics in vitro.Oral

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Surgery,OralMedicine,OralPathology1973;36:856-871.

12.AriH,Yaşar E,BellíS.Effects of NaOClon bond strengths of resin cementstorootcanaldentin.JournalofEndodontics2003;29:248-251.

13.Yiu C,Garcia-Godoy F,Tay F,Pashley D,Imazato S,King N,etal.A nanoleakage perspective on bonding to oxidized dentin.JournalofDental Research2002;81:628-632.

14.Ozturk B,ÖzerF.EffectofNaOClon bondstrengthsofbonding agentsto pulpchamberlateralwalls.JournalofEndodontics2004;30:362-365.

15.IshizukaT,KataokaH,YoshiokaT,SudaH,IwasakiN,TakahashiH,etal. EffectofNaClO treatmenton bonding to rootcanaldentin using a new evaluationmethod.DentalMaterialsJournal2001;20:24-33.

16.Rueggeberg F, Margeson D. The effect of oxygen inhibition on an unfilled/filled composite system. Journal of Dental Research 1990;69:1652-1658.

17.AriH,Erdemir A.Effects of endodontic irrigation solutions on mineral content of root canal dentin using ICP-AES technique. Journal of Endodontics2005;31:187-189.

18.Sim T,Knowles J,Ng YL,Shelton J,Gulabivala K.Effect of sodium hypochlorite on mechanicalproperties ofdentine and tooth surface strain.

InternationalEndodonticJournal2001;34:120-132.

19.Nakabayashi N.Dentinalbonding mechanisms.Quintessence international 1991;22:73.

20.Frankenberger R, Perdigao J, Rosa B, Lopes M. ‘No-bottle’vs

‘multi-bottle’dentin adhesives—a microtensile bond strength and morphologicalstudy.DentalMaterials2001;17:373-380.

21.Vongphan N,SenawongseP,SomsiriW,HarnirattisaiC.Effectsofsodium ascorbateon microtensilebondstrength oftotal-etching adhesivesystem to NaOCltreateddentine.JournalofDentistry2005;33:689-695.

22.Marending M,LuderH,BrunnerT,KnechtS,Stark W,ZehnderM.Effect ofsodium hypochlorite on human root dentine–mechanical,chemicaland

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23.Trope M, Maltz DO, Tronstad L. Resistance to fracture of restored endodonticallytreatedteeth.DentalTraumatology1985;1:108-111.

24.Pashley DH,Sano H,CiucchiB,Yoshiyama M,Carvalho RM.Adhesion testingofdentinbondingagents:areview.DentalMaterials1995;11:117-125.

저작자표시

2015년 2월 석사학위 논문

Ef f e c tofde nt i ns ur f ac er e moval ont heNaOCl -t r e at e dde nt i n

조선대학교 대학원

치 의 학 과

송 미 연

Ef f e c tofde nt i ns ur f ac er e moval ont heNaOCl -t r e at e dde nt i n

차아염소산나트륨 용액으로 처리된 상아질 표면의 삭제 효과

2 01 5 년 2 월 2 5일

조선대학교 대학원

치 의 학 과

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Ef f e c tofde nt i ns ur f ac er e moval ont heNaOCl -t r e at e dde nt i n

지도교수 황 호 길

이 논문을 치의학 석사학위신청 논문으로 제출함.

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송 미 연

송미연의 석사학위논문을 인준함.

위원장 조선대학교 교수 최 한 철 인 위 원 조선대학교 교수 황 호 길 인 위 원 조선대학교 교수 민 정 범 인

2 0 1 4 년 1 2 월

CONTENTS

TABLE LEGENDS

FI GURE LEGENDS

국 문 초 록

차아염소산나트륨 용액으로 처리된 상아질 표면의 삭제 효과

I .I nt r oduct i on

I I .Mat er i al sandMet hods

1.Speci men pr epar at i on

2.Mi cr ot ensi l ebondst r engt h t est

3.St at i st i calanal ysi s

I I I .Resul t s

1.Mi cr ot ensi l ebondst r engt h

I V.Di scussi on

V.Concl usi ons

Ref er ences