Safe use of ozone gas in enamel adhesion

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Revista

Portuguesa

de

Estomatologia,

Medicina

Dentária

e

Cirurgia

Maxilofacial

ww w . e l s e v i e r . p t / s p e m d

Investigation

Safe

use

of

ozone

gas

in

enamel

adhesion

Patrícia

T.

Pires

a,∗

,

João

C.

Ferreira

a

,

Soﬁa

A.

Oliveira

b

,

Mário

J.

Silva

a

,

Paulo

R.

Melo

a

a_Faculty_of_Dental_Medicine,_University_of_Oporto,_Oporto,_Portugal b_Faculty_of_Dental_Medicine,_University_of_Lisbon,_Lisbon,_Portugal

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received13February2012

Accepted7May2012

Availableonline12July2012

Keywords: Shearstrength Dentalenamel Dentin-bondingagents Ozone

a

b

s

t

r

a

c

t

Purpose:Evaluatetheshearbondstrengthofaself-etchingsystemtoenamelpretreated

withozoneanditstypeoffracture.

Matherialandmethods:Thirtysoundbovineincisorswerebisectedandpolishedjustbefore

theapplicationoftheadhesivesystem.Theadhesionareawaslimitedtoa3-mmdiameter.

Thespecimenswererandomlyassignedtotheexperimentalgroups(n=15)and

compos-iteresincylinderswereaddedtothetestedsurfaces,aftertheapplicationoftheadhesive

accordingtothemanufacturer’sinstructions.GroupG1(AdheSE®_with_ozone)_was

previ-ouslypreparedwithozonegasfromtheHealOzoneunit(Kavo®₎_for₂₀_s,_groups_G2_(AdheSE®₎

wasusedascontrol.Thespecimenswerestoredindistilledwaterfor24hat37◦_C_with_100%

humidity,beforebeingthermocycled.Thetypeoffracturewasanalyzedunderscanning

electronicmicroscopeandthedataweresubmittedtoShapiro–Wilk,Student’st-testand

Chi-squaredstatisticalanalyses.

Results:ThemeanbondstrengthswereG1:15.0MPa(77.8%ofadhesivefracturesbetween

enamelandadhesive)andG2:13.1MPa(36.4%ofadhesivefracturesbetweenenameland

adhesive).

Conclusion:Theshearbondstrengthofaself-etchingsystemwasnotinﬂuencedbythe

previousapplicationofozonegas.

ElsevierEspaña,S.L.Allrightsreserved.

Seguranc¸a

da

aplicac¸ão

de

ozono

na

adesão

ao

esmalte

Palavras-chave:

Forc¸aderesistênciaadesiva

Esmaltedentário

Adesivosdentários

Ozono

r

e

s

u

m

o

Objectivo:Avaliarasforc¸asderesistênciaadesivadeumsistemaadesivoauto-condicionador

noesmaltepré-tratadocomozonoeotipodefractura.

Materialemétodos:Trintaincisivoshígidosdeorigembovinaforamseccionadosdeformaa

separaracoroadaraízepolidosantesdacolocac¸ãodosistemaadesivo.Aáreadeadesão

foilimitadaa3mmdediâmetro.Osespécimesforamaleatoriamentedivididos(n=15)e

cilindrosderesinacompostaforamadicionadosàssuperfíciesdetesteapóscadasistema

adesivotersidoaplicadodeacordocomasinstruc¸õesdofabricante.OgrupoG1(AdheSE®

comozono)foicondicionadocomgásdeozonogeradopeloaparelhoHealOzone(Kavo®_),

∗ _{Corresponding}_author_.

E-mailaddress:patriciapires75@gmail.com(P.T.Pires).

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durante20segundos,G2(AdheSE®₎_funcionou_como_controlo._Os_espécimes_foram_mantidos

emáguadestiladadurante24horasnumaestufaa37◦Ccom100%dehumidade,antes

datermociclagem.OtipodefracturaanalisadoaoMEVeosdadossubmetidosàanálise

estatísticaShapiro–Wilk,Student’st-testeChi-squared.

Resultados:Asmédiasderesistênciaadesivaforam:G1:15,0MPa(77,8%defracturasadesivas

entreoesmalteeoadesivo)eG4:13,1MPa(36,4%defracturasadesivasentreoesmalteeo

adesivo).

Conclusão:Osvaloresderesistênciaadesiva dosistemaadesivoauto-condicionadornão

foraminﬂuenciadospelaaplicac¸ãopréviadegásdeozono.

España,S.L.Todososdireitosreservados.

Introduction

Currently,it isnotpossibletoassurethat atooth cavityis

bacteriologicallyaseptic,thus anantibacterial treatmentof

thedentalsurfaceprevioustorestorationhasbeenadvised.1

Indeed,someauthorshavestartedtoapplyOzoneasa

disin-fectingagent.2_Ozone,_with_its_{antibacterial}_action_due_to_its

strongoxidizingactivity,isanimportantdisinfectingagent.3–5

Recentresearch revealsthe bactericidal actionofozone

against Streptococcus mutans and other bacteria commonly

foundincervicalcaries.5,6 _However,_there_are_very_few_data

concerningits effecton dental adhesion.7 _Previous_studies

demonstratedthatoxygenandotheroxidantagents(suchas

whiteningagents)haveanegativeinﬂuenceonbondstrength

valuesofdental-enameladhesives.

Resin–enamel adhesion is one of the most signiﬁcant

advancesinthe historyofDentistry8 _and _it _is_used_in_our

daysasasimpleeffectiveprocedure,whenusingatotal-etch

technique.9 _{Nevertheless,} _the _enamel _etching _concept _has

beenimprovedthroughtheyearsandnewadhesivesystems

havebeendevelopedandreleased.10,11

Self-etchingsystemsweredevelopedtosimplifyand

elim-inate some ofthe clinical steps associatedto total-etch.11

Self-etching adhesives are based on acidic monomersthat

simultaneously condition and primeenamel.12 _The_primer

is applied on the enamel and resin tags are form. Smear

layerisdissolvedandincorporatedintothebondingprocess,

thereforethetoothnolongerrequiresrinsing,asitdoeswith

etch-and-rinse.13,14

One of the questions that arise is whether the acidic

monomerused inself-etchadhesive systemsis capableof

promotingenameldemineralization,makingitareliableand

durableadhesion.15,16_Shear_bond_strength_tests_aim_to

estab-lishanumericvalueinordertodeterminehowstrongthat

bondis.17_In_addition,_since_no_rinsing_occurs_after_the

appli-cationofthe self-etching,we may speculate thatself-etch

systemsaremoresusceptibletoOzoneresidualoxygen.

Thisstudyaimedtodeterminewhetherozonegasissafe

touse inbovineenamelregardingits effectonShearBond

Strength(SBS)whenusingaself-etchingadhesive(AdheSE®_,

IvoclarvivadentAG,Liechtenstein).

Materials

and

methods

Thirtysoundbovineincisorswereextractedfornolongerthan

amonthandkeptindistilledwaterat4◦C.Afterthisperiod

oftime,the teethwere keptina0.5%chloraminesolution

foraweekandbisectedwithamicrotomer(Accuton-Struers,

Copenhagen,Denmark)toseparatethecrownfromtheroot.

Theywerethenpolishedwitha240-gritsandpapertocreate

aﬂatsurfaceandpolished,again,witha320-gritsandpaper

(CarbimetBuehler-met,Buehler,LakeBluff,IL)tosimulatethe

smearlayerjustbeforetheapplicationofthe adhesive

sys-tem. Polyesterﬁlm (Mylar, Dupont Corp., DE, USA),with a

3-mmdiameterholewasusedtorestricttheadhesionarea.

Specimenswererandomlyassignedtooneoftwo

experimen-talgroups(n=15)andcompositeresincylinderswerebonded

tothetestedsurfaces,aftertheapplicationoftheadhesive

accordingtothemanufacturer’sinstructions:AdheSEPrimer

wasappliedwithabrush.Oncethesurfacewascompletely

coated, the primerwas brushedinto the entiresurfacefor

another 15s. Thetotal reaction timewas notshorterthan

30s.Theprimerwas dispersedwithastrongstreamofair

untilthemobileliquidwasnolongervisible.Then,AdheSE

Bondwasappliedanddispersedwithaweakstreamofairand

polymerizedfor10s.GroupG1:AdheSE®_with_ozone_(Ivoclar

vivadentAG, Liechtenstein)was conditionedfor20seconds

withozonegasfromthe HealOzoneunit(Kavo®_, _Germany)

usinga5-mmdeliverycup(green).GroupsG2(AdheSE®₎_was

usedas control,notreceiving ozonebeforethe application

oftheadhesivesystem.Theadhesivematerialsusedinthis

studyarelistedinTable1alongwiththemanufacturers’

com-positions, batchnumbers andcodes.Afterthis application,

specimenswerekeptindistilledwaterfor24hat37◦Cwith

100%humidity(Hemmet, Schwabach,Germany)inorderto

obtainthemaximumresinpolymerization,beforebeing

ther-mocycled(Aralab,mod200E,Cascais,Portugal)for500cyclesat

5◦and55◦Cfor20s18_in_each_bath_and_submitted_to_shear

test-ingatacrossheadspeedof0.5mm/min(Instron,model4502,

seriesH3307,InstronLtd,Bucks,England).Thetypeoffracture

wasanalyzedunderSEM(JEOLJSM6301F,Tokyo,Japan).

Frac-tureswereclassiﬁedbyasingleexperiencedinvestigator,as

eitheradhesive,cohesive(resinorenamel)ormixed19_and_the

dataweresubmittedtoShapiro–Wilk,toevaluatethe

normal-ityandStudent’st-testtocomparebothgroups.Chi-squared

statisticalanalyseswereusedtocomparethetypeoffractures.

Results

ThemeanShearBondStrengths(SBS)showninFig.1were

G1: 15.0MPa (77.8% of adhesive fractures between enamel

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Table1–Restorativeandadhesivematerials.

Materials Function Composition Batch#

AdheSE®_(lvoclar_vivadent

AG,Liechtenstein)

Adhesivesystem Primer:Mixtureofdimethacrylate,

phosphonicacidacrylate,water,initiators

andstabilizers;Bond:Bis-GMA,HEMA,

GMDA,

J03385

SynergyD6(Coltene

whaledentGmbH+Co.KG

Germany)

Restorativematerial Methacrylates,bariumglasssilanized,

amorphoussilica 0145721 12.0 12.5 13.0 13.5 14.0 15.0

AdheSE with ozone AdheSE

13.1 14.5

15.0 15.5 MPa

Fig.1–Meanshearbondstrength(MPa).

betweenenamel and adhesive).A typicalfracture between enamelandadhesivecanbeobservedinFig.3.

Nostatistic differences were foundbetween G1 and G2

(p>0.05). The enamel surface obtained with and without

ozonecanbeseeninFig.2.

Discussion

Inthepresentstudy,AdheSE®_mean_SBS_values_did_not_differ

signiﬁcantlybetweenOzonepretreatedgroupandthecontrol

group(15.0MPaand13.1MPawithOzone pretreatmentand

control,respectively).

Theresultofthisworkseemstoshownoharminﬂuence

ofozoneintermsofShearBondStrength.

Inthisstudy,ozonewasappliedonenamelfor20s.Ozone

eliminates99.9%ofbacteriapresentafterthisperiod.2,3,20,21

Thisveryshortozonegasapplicationtimewhencompared

with other potential oxidants, like bleaching agents, may

explainwhyozonegasdidnotdecreasedSBSvaluesinthe

presentstudy,asitwasexpected.22,23

Consistentwithourresults,Schmidlinetal.7_found_no

sta-tisticaldifferencesonSBSvalueswhenatotal-etchsystem

wasused.InastudyconductedinFebruary2008,24_SBS

val-uesoforthodonticbracketstoenamelhadnodifferencesin

groupstreatedwithorwithoutozone.Thesameresultswere

obtainedinacontemporaneousstudy.22

Fig.2–Enamelsurfaceafterbeingtreatedwiththeself-etchingAdheSE®with(A)andwithout(B)Ozone.FESEM,2000×, Gold.Enamelprismscanbeidentiﬁableinalltheobservedspecimens.

Fig.3–Adhesivefracturebetweenenamelandadhesive(Caption:A–Compositesurfacemostlycoveredbytheadhesive;B –Enamelsurfacenotcoveredbytheadhesive;C–Enamelsurfacewithenamelrods).

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OzoneisapromisingalternativeinmodernDentistry.The

applicationofozonetoenamelmaybeimportanttodisinfect

thesurfacebeforeapplyingsealantsororthodonticbrackets.

Recentstudiesshown itsabilitytoprovideanantibacterial

treatmentagainstS.mutansevenafter8weeks.25_The_current

workcomplementsagrowingbodyofworkdemonstratingthe

safeusageofozoneindentaladhesion.7,22,24

Investigationfocusingonthelong-termeffectsis

recom-mendedforfurtherresearch.

AdheSE®_is_a_two-step_self-etching_adhesive_developed_with

the expectation ofdecreasing the time and technical

sen-sitivity of the adhesion process. It is intended that they

willsubstitutethetotal-etchingadhesives,asmanufacturers

claimthattheseproductshaveasimilarbehaviorandare

eas-iertoworkwith.26_The_main_concern_about_self-etch_materials

isthefactthattheymaynotbeabletoetchefﬁcientlytooth

enamel.16_The_results_of_published_studies_on_the_efﬁcacy_of

bondingtoenamelarenotpaciﬁc,27_on_the_contrary_to_etch

andrinse;thiswasthereasonforusingaself-etchingsystem

inourstudy.

TheresultsofAdheSE® _SBS_values_in_enamel_were _low,

however, our ﬁndings are consistent with other several

studies.11,26,28,29Someauthorsstatethatbondstrengthof

self-etchadhesivesisnotasgoodasadhesivesystemsthatuse

totaletchingwithphosphoricacid.30

Themainreasonmightbethetotal-etchacidiccapacity

ofdemineralizingenamelbetter and deeperthan self-etch

adhesives.

However, Hannig et al.31 _using _self-etching _adhesives,

foundsimilarSBSwithorwithoutpre-etchingenamel

show-ing that a better and deeper demineralization might not

meanhigherSBSvalues.Otherresearchershaveshownthat

althoughdemineralizationpatternsarenotasaccentuatedas

self-etchadhesives, theyreach highlysatisfactory levels of

bondstrength.11,32,33

Self-etchingadhesivesarelesssusceptibletotheoperative

proceduresandmightshowsimilarresultsinvivoandinvitro,

whichmay notbetrue fortotal-etchingadhesives thatare

moresusceptibletothetechnique.

Concerningthetypeoffracture,itwasnotpossibleto

with-drawanyconclusionsinourstudy,sincethedifferenceswere

notstatisticallysigniﬁcant.

Conclusions

GaseousozonecausednoreductioninShearBondStrength

valuesin enamel whenself-etch systems were used.

Self-etching systems were not inﬂuenced by the previous

applicationofozonegasinshearbondstrength.

Ethical

disclosures

Protectionofhumanandanimalsubjects.Theauthorsdeclare

thattheproceduresfollowedwereinaccordancewiththe

reg-ulationsoftheresponsibleClinicalResearchEthicsCommittee

andinaccordancewiththoseoftheWorldMedicalAssociation

andtheHelsinkiDeclaration.

Conﬁdentialityofdata.Theauthorsdeclarethatnopatient

dataappearsinthisarticle.

Righttoprivacyandinformedconsent.Theauthorsdeclare

thatnopatientdataappearsinthisarticle.

Conﬂicts

of

interest

Theauthorshavenoconﬂictsofinteresttodeclare.

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