Microleakage Assessment of a Repaired Na

Scientific Article

Microleakage Assessment of a Repaired, Nano-filled, Resin-based Fissure Sealant

Ghalib Walid Qadri, BDS, MSc1 _{• Siti Noor Fazliah Mohd Noor, BDS, MClinDent, MFDS}2 _{• Dasmawati Mohamad, BEng Chem Eng, MSc, PhD}3

Abstract: Purpose: The purpose of this study was to evaluate the effects of different repairing techniques of a fractured sealant on microleakage in vitro. Methods: A nano-filled flowable composite (Filtek Z350) was placed on the occlusal surfaces of 112 intact extracted molars following cleaning by prophylaxis and acid etching. Sealant failure was produced on the entire sample. The teeth were then randomly allocated into 4 groups, each representing a different method of repair: group 1 (control)—prophylaxis brush followed by acid etching and 10 seconds of curing time; group 2—prophylaxis brush, acid etching, application of bonding agent, and 10 seconds of curing time; group 3—prophylaxis brush, acid etching, and 5 seconds of curing time; and group 4—prophylaxis brush, acid etching, and 20 seconds of curing time. Then, they were painted with varnish and immersed in 1% methylene blue. The teeth were then sectioned, and a total of 648 surfaces were scored for microleakage. Results: Statistical analysis did not demonstrate any one method of repair to be superior to the control method. There were no significant differences in microleakage between 10 and 20 seconds of curing time. Conclusion: Prophylaxis brush, acid etching, and light-emitting diode light curing for 10 seconds seems to be the simplest and the most appropriate method of repair and is, therefore, recommended. (Pediatr Dent 2009;31:389-94) Received May 18, 2008 | _{Last Revision August 24, 2008} | _{Revision Accepted August 29, 2008}

KEYWORDS: FISSURE SEALANT, MICROLEAKAGE, NANO-COMPOSITE, FLOWABLE COMPOSITE

Fissure฀sealant฀(FS)฀was฀introduced฀as฀a฀method฀to฀prevent฀ occlusal฀caries฀more฀than฀30฀years฀ago.฀Since฀then,฀FS฀usage฀฀ has฀increased฀steadily฀and฀its฀effectiveness฀has฀been฀proven฀ in฀many฀studies.1-3_{฀Nowadays,฀it฀is฀considered฀to฀be฀the฀฀}

most฀effective฀caries-preventive฀measure฀that฀may฀be฀offered฀ to฀a฀patient.4

The฀cariostatic฀properties฀of฀the฀resin฀sealants฀are฀main-฀ ly฀attributed฀to฀the฀physical฀obstruction฀of฀the฀pits฀and฀fis-฀ sures฀and฀remain฀completely฀intact฀and฀bonded฀to฀enamel฀ surfaces.3,5_{฀This฀prevents฀colonization฀of฀the฀pits฀and฀fissures฀}

with฀new฀bacteria฀and฀also฀prevents฀the฀penetration฀of฀fer-mentable฀carbohydrates฀to฀any฀bacteria฀remaining฀in฀the฀฀ pits฀and฀fissures.฀Thus,฀the฀remaining฀bacteria฀cannot฀pro-฀ duce฀acid฀in฀cariogenic฀concentrations.6

Sealant฀retention฀and฀integrity฀of฀the฀enamel-sealant฀ interface฀determines฀to฀a฀great฀extent฀the฀caries฀reduction฀ ability฀and฀effectiveness฀of฀a฀FS.3,7_{฀The฀main฀problem฀that฀฀}

FS฀encounters฀is฀microleakage,฀which฀may฀lead฀to฀deteriora-tion฀of฀the฀material—increasing฀the฀possibility฀of฀develo-฀ ping฀caries฀and,฀thus,฀interfering฀in฀the฀long-term฀success฀฀ of฀the฀technique.

฀

Being฀a฀technique-sensitive฀material,฀resin฀FS฀may฀fail฀฀ with฀a฀rate฀range฀between฀5฀percent฀and฀10฀percent฀each฀ year.8_{฀The฀predominant฀cause฀of฀sealant฀failure,฀at฀least฀in฀฀}

the฀short-term,฀is฀salivary฀contamination฀of฀the฀etched฀ surface.9,10

The฀necessity฀of฀recall฀and฀maintenance฀for฀FS฀is฀based฀ on฀the฀understanding฀that฀partial฀loss฀of฀a฀sealant฀leads฀to฀a฀ surface฀equally฀at฀risk฀for฀caries฀as฀one฀that฀was฀never฀sealed.฀ One-time฀sealant฀placement฀does฀not฀impart฀any฀long-term฀ caries฀protection฀unless฀the฀sealant฀remains฀in฀place฀and฀in-฀ tact.฀Loss฀of฀coverage฀of฀any฀susceptible฀pit฀or฀fissure฀leads฀฀ to฀an฀immediate฀risk฀of฀caries฀attack฀for฀the฀uncovered฀area.8_฀

Policy฀documents฀and฀clinical฀guidelines฀strongly฀advise฀ monitoring฀and฀repair฀or฀retreatment฀of฀lost฀or฀fractured฀ sealants฀to฀ensure฀longevity฀and฀caries฀protection.11,12฀

In฀this฀study฀and฀in฀an฀attempt฀to฀increase฀the฀retention฀ of฀sealants฀and฀to฀eliminate฀microleakage,฀the฀use฀of฀recent฀ nano-adhesive฀systems฀and฀innovative฀light-emitting฀diode฀ (LED)฀curing฀units฀was฀proposed฀as฀the฀next฀step฀in฀seal-฀ ant฀improvement฀for฀children฀and฀young฀adults.

Currently฀there฀is฀only฀one฀English-language฀reference฀ in฀the฀literature฀on฀the฀most฀effective฀method฀of฀repair฀of฀ a฀fractured/deficient฀fissure฀sealant.13_{฀Therefore,฀the฀aims฀of฀฀}

this฀randomized,฀controlled,฀in฀vitro฀study฀were฀to:฀evaluate฀฀ the฀effect฀of฀4฀different฀techniques฀of฀repair฀of฀a฀fractured,฀ nano-filled,฀ resin-based฀ fissure฀ sealant฀ on฀ the฀ level฀ of฀฀

1_{Dr. Qadri is is a Paediatric Dentist, and} 2_{Dr. Noor is a lecturer, both in the Paediatric}

Dentistry Unit, and 3_{Dr. Mohamad is a lecturer in a Biomaterials Unit, all in the School}

microleakage;฀and฀determine฀the฀effect฀of฀different฀LED฀฀ light฀curing฀times฀on฀microleakage฀of฀a฀repaired฀nano-filled฀ resin-based฀fissure฀sealant฀in฀vitro.

Methods

After฀obtaining฀approval฀of฀the฀research฀and฀ethics฀commit-฀ tees฀(Internal฀Review฀Board,฀Universiti฀Sains฀Malaysia,฀ IRB฀Reg.฀No.฀00004494),฀112฀extracted,฀intact฀permanent฀฀ molars฀were฀selected฀and฀chosen฀for฀this฀study.฀The฀teeth฀ were฀obtained฀from฀dental฀clinics฀of฀the฀University฀Science฀ Malaysia,฀Kelantan,฀Malaysia.฀Most฀of฀the฀teeth฀had฀erup-฀ ted฀before฀extraction.฀The฀teeth฀were฀stored฀in฀0.2฀percent฀ thymol฀ in฀ a฀ disposable฀ plastic฀ container฀ following฀ ex-฀ traction฀and฀used฀within฀3฀months.

PS฀Software฀(Version฀12.00,฀Nashville,฀Tenessee,฀USA)14_฀

was฀used฀to฀calculate฀the฀sample฀size฀based฀on฀comparing฀2฀ proportions฀to฀detect฀a฀10฀percent฀difference฀in฀microleak-฀ age,13_{฀with฀anticipation฀of฀5฀percent฀broken฀teeth฀during฀}

sectioning.

After฀cleaning฀and฀gross฀debridement฀of฀the฀teeth,฀the฀ occlusal฀surfaces฀were฀cleaned฀with฀a฀prophylaxis฀brush฀ rotating฀at฀a฀slow฀speed฀for฀10฀seconds.฀The฀teeth฀were฀rinsed฀ with฀an฀air-water฀spray฀for฀30฀seconds,฀dried฀with฀an฀oil-฀ free฀compressed฀airjet฀for฀10฀seconds,฀and฀one฀proximal฀half฀ of฀the฀occlusal฀surface฀was฀etched฀with฀37฀percent฀phos-฀ phoric฀acid฀liquid฀(Scotchbond฀Etchant,฀3M฀ESPE,฀Seefeld,฀ Germany)฀for฀15฀seconds,฀as฀recommended฀by฀the฀manufac-turer’s฀instructions.฀The฀Filtek฀Z350฀flowable฀restorative฀฀ (3M฀ESPE,฀Seefeld,฀Germany)฀was฀applied฀to฀the฀entire฀ occlusal฀surface฀of฀the฀teeth฀directly฀from฀its฀dispensing฀tip.฀฀ A฀small฀spoon฀excavator฀was฀placed฀on฀the฀untreated฀(un-etched)฀proximal฀half฀of฀the฀occlusal฀surface฀into฀the฀uncured฀ sealant฀to฀create฀a฀point฀of฀application฀inside฀the฀sealant.฀ Finally,฀the฀material฀was฀light฀cured฀for฀10฀seconds฀while฀฀ the฀spoon฀excavator฀was฀still฀at฀the฀point฀of฀application.

Light฀activation฀was฀performed฀using฀an฀LED฀curing฀ light฀(Elipar฀FreeLight฀2฀LED฀Curing฀Light,฀3M฀ESPE)฀ with฀an฀output฀intensity฀of฀1,300฀mW/cm2_{,฀by฀placing฀the฀฀}

curing฀tip฀approximately฀1฀mm฀away฀from฀the฀occlusal฀sur-฀ face.฀The฀light฀curing฀unit฀was฀checked฀for฀a฀minimum฀฀ output฀intensity฀of฀at฀least฀1,300฀mW/cm2_{฀by฀a฀hand-held฀}

radiometer฀(Caulk,฀Dentsply,฀Milford,฀Del)฀to฀ensure฀that฀฀ the฀unit฀was฀operating฀properly฀after฀each฀application.

The฀excavator฀was฀removed฀slowly฀after฀light฀curing฀in฀฀ such฀a฀way฀that฀the฀polymerized฀sealant฀was฀broken฀by฀the฀ excavator฀at฀the฀point฀of฀application฀and฀half฀of฀the฀sealant฀ was฀removed.฀This฀procedure฀resulted฀in฀one฀half฀of฀the฀ occlusal฀surface฀being฀covered฀by฀the฀sealant฀and฀one฀half฀ devoid฀of฀the฀sealant฀and฀ready฀to฀be฀resealed.฀The฀teeth฀฀ were฀randomly฀assigned฀to฀one฀of฀4฀groups,฀each฀containing฀ 28฀teeth฀(168฀surfaces)฀using฀randomization฀software฀(http:// www.randomization.com)฀and฀a฀sealed฀enveloped฀method฀฀ for฀randomization.

The฀teeth฀were฀then฀stored฀in฀artificial฀saliva฀(Biotene,฀ Laclede,฀Inc,฀California,USA)฀for฀1฀week,฀after฀which฀the฀

teeth฀were฀removed฀from฀the฀artificial฀saliva฀and฀washed฀฀ with฀an฀air-water฀spray.฀The฀teeth฀were฀then฀subjected฀to฀1฀฀ of฀the฀following฀techniques฀of฀repair:

Group฀1:฀Prophylaxis฀brush฀and฀acid฀etching฀(control.)฀ Traditional฀prophylaxis฀with฀a฀brush฀rotating฀at฀a฀slow฀speed฀ was฀used฀without฀pumice฀or฀prophylaxis฀paste.฀Following฀฀ the฀prophylaxis,฀the฀occlusal฀surfaces฀were฀rinsed฀with฀an฀ air-water฀spray฀for฀30฀seconds฀and฀dried฀for฀15฀seconds฀฀ with฀compressed฀air,฀followed฀by฀etching฀with฀37฀percent฀ phosphoric฀acid฀liquid฀for฀15฀seconds.฀The฀etchant฀was฀฀ washed฀off฀with฀the฀water฀spray฀for฀30฀seconds฀and฀the฀฀ tooth฀was฀dried฀with฀compressed฀air฀for฀15฀seconds.฀Filtek฀ Z350฀flowable฀restorative฀was฀reapplied฀on฀the฀denuded฀ proximal฀half฀of฀the฀teeth฀(the฀fractured/deficient฀part)฀and฀ allowed฀to฀flow฀over฀the฀other฀proximal฀half฀with฀the฀intact฀ sealant.฀The฀Z350฀was฀cured฀using฀an฀LED฀curing฀light฀for฀ 10฀seconds.

Group฀2:฀Prophylaxis฀brush,฀acid฀etching,฀and฀application฀ of฀bonding฀agent฀(test).฀All฀of฀the฀steps฀were฀identical฀to฀ group฀1.฀In฀this฀group,฀however,฀a฀layer฀of฀bonding฀agent฀ (Adper฀Single฀Bond฀2฀Adhesive,฀3M฀ESPE)฀was฀applied฀on฀฀ the฀tooth’s฀whole฀occlusal฀surface฀with฀a฀disposable฀brush,฀ gently฀air฀thinned฀for฀5฀seconds,฀cured฀for฀10฀seconds,฀re-฀ sealed฀with฀Filtek฀Z350฀on฀the฀denuded฀proximal฀half฀of฀ the฀teeth,฀and฀allowed฀to฀flow฀over฀the฀other฀proximal฀half.฀ Finally,฀each฀tooth฀was฀cured฀using฀an฀LED฀curing฀light฀for฀ 10฀seconds.

Group฀3:฀Prophylaxis฀brush,฀acid฀etching,฀and฀5฀seconds฀ curing฀time฀(test).฀The฀steps฀were฀identical฀to฀group฀1,฀ex-฀ cept฀the฀resealed฀FS฀was฀cured฀for฀5฀seconds.

Group฀4:฀Prophylaxis฀brush,฀acid฀etching,฀and฀20฀se-฀ conds฀curing฀time฀(test).฀The฀steps฀were฀identical฀to฀group฀฀ 1,฀except฀the฀resealed฀FS฀was฀cured฀for฀20฀seconds.฀

The฀teeth฀from฀the฀4฀groups฀were฀stored฀in฀artificial฀ saliva฀for฀1฀week฀to฀simulate฀the฀oral฀condition.฀After฀1฀฀ week,฀all฀teeth฀were฀rinsed฀with฀an฀air-water฀spray฀and฀฀ dried฀with฀compressed฀air.฀

The฀apices฀of฀the฀teeth฀were฀sealed฀with฀sticky฀wax฀and฀ coated฀with฀2฀layers฀of฀nail฀varnish฀(Max฀Factor฀Diamond฀ Hard,฀Procter฀and฀Gamble,฀Weybridge,฀UK)฀within฀1฀mm฀ of฀the฀fissure฀sealant.฀Two฀different฀nail฀varnish฀colors฀were฀ used฀to฀differentiate฀the฀repaired฀and฀nonrepaired฀prox-฀ imal฀halves฀of฀the฀teeth’s฀occlusal฀surfaces฀and฀to฀ensure฀ complete฀coverage฀of฀both฀layers.฀

to฀facilitate฀their฀mounting฀in฀the฀sectioning฀machine฀and฀฀ to฀prevent฀the฀material฀from฀chipping.

After฀the฀acrylic฀block฀hardened,฀each฀tooth฀was฀sec-฀ tioned฀longitudinally฀in฀a฀mesiodistal฀plane฀to฀achieve฀3฀฀ cuts฀with฀a฀hard฀tissue฀cutter฀(Exact)฀equipped฀with฀a฀water-cooled฀diamond฀impregnated฀band฀saw.฀This฀resulted฀in฀4฀ sections,฀each฀approximately฀1฀mm฀in฀thickness,฀with฀6฀sur-฀ faces฀to฀score฀per฀tooth.฀

A฀ Leica฀ image฀ analyzer฀ system฀ Q550฀ MW฀ (Leica,฀ Heerbrugg,฀Switzerland),฀consisting฀of฀a฀light฀microscope,฀ at฀a฀magnification฀of฀X40฀(Leica,฀Heerbrugg,฀Switzerland)฀ and฀equipped฀with฀a฀video฀camera฀linked฀to฀a฀computer,฀was฀ used฀to฀record฀the฀microleakage.฀All฀measurements฀in฀this฀ experiment฀were฀performed฀using฀the฀Leica฀Q550฀software฀ 3.2.1.฀(Leica,฀Cambridge,฀UK).

In฀each฀sample,฀microleakage฀was฀measured฀by฀tracing฀฀ the฀dye฀penetration฀from฀the฀sealant’s฀border.฀The฀micro-฀ leakage฀proportion฀was฀expressed฀as฀the฀length฀of฀dye฀pene-tration฀in฀micrometers฀(µm)฀divided฀by฀the฀length฀of฀the฀ sealant-tooth฀interface.฀The฀photographed฀images฀were฀ independently฀and฀blindly฀scored฀for฀microleakage฀by฀a฀ well-trained฀examiner,฀using฀Grande฀et฀al.15_{฀scoring฀system,฀}

which฀was฀as฀follows:฀0=no฀dye฀penetration;฀1=dye฀penetra-฀ tion฀into฀the฀occlusal฀third฀of฀the฀enamel-sealant฀interface;฀ 2=dye฀penetration฀into฀the฀middle฀third฀of฀the฀interface;฀฀ and฀3=dye฀penetration฀into฀the฀apical฀third฀of฀the฀interface.฀ The฀worst฀score฀for฀each฀examined฀surface฀was฀recorded.

After฀determining฀the฀microleakage฀scores฀for฀all฀the฀ surfaces,฀they฀were฀scored฀again฀2฀weeks฀later฀by฀the฀same฀ researcher.฀Fifteen฀percent฀of฀the฀total฀sample฀size฀(15%,฀฀

N=89฀surfaces)฀were฀selected฀using฀computer-generated฀ran-฀

dom฀numbering฀to฀determine฀intraexaminer฀reliability.

Results

Dye฀penetration฀was฀observed฀on฀teeth฀from฀both฀the฀test฀ and฀control฀groups.฀Of฀the฀original฀112฀extracted฀perma-฀ nent฀molars,฀4฀were฀damaged฀in฀the฀sectioning฀procedures฀฀ and฀considered฀lost฀from฀the฀study฀sample.฀One฀tooth฀be-฀ longed฀to฀each฀group.฀The฀remaining฀108฀teeth฀yielded฀648฀ total฀surfaces.฀Table฀1฀shows฀the฀microleakage฀scores฀ac-฀ cording฀to฀the฀surface฀level฀analysis.฀No฀leakage฀(score฀0)฀฀ was฀found฀on฀481฀surfaces฀out฀of฀648฀total฀surfaces฀(74%).฀

Acid฀etching,฀followed฀by฀the฀application฀of฀bonding฀฀ agent฀(group฀2),฀had฀the฀most฀number฀of฀sealants฀exhibiting฀฀ no฀leakage฀(score฀0)฀at฀81฀percent฀(131/162)฀as฀well฀as฀the฀least฀ number฀of฀sealants฀displaying฀maximum฀leakage฀(score฀3)฀at฀ 11฀percent฀(17/162).฀The฀statistical฀analysis฀using฀Pearson’s฀ chi-square฀test฀indicated฀no฀significant฀difference฀between฀ groups฀1฀and฀2฀(฀P=0.18).

Group฀3,฀which฀had฀been฀cured฀for฀5฀seconds,฀had฀the฀ least฀number฀of฀surfaces฀with฀no฀leakage฀66฀percent฀(107/฀ 162)฀and฀the฀highest฀number฀of฀sealants฀with฀maximum฀ leakage฀at฀25฀percent฀(40/162).฀Statistical฀analysis฀using฀฀ the฀Pearson฀chi-square฀test฀indicated฀a฀significant฀difference฀ between฀this฀group฀and฀group฀1(control฀group)฀(P=0.02).

Group฀4,฀which฀had฀been฀cured฀for฀20฀seconds,฀showed฀ lower฀microleakage฀than฀group฀1฀(control฀group).฀However฀฀ there฀was฀no฀significant฀difference฀(P=0.89),฀between฀these฀ 2฀repair฀techniques.

The฀5-second฀curing฀time฀led฀to฀inferior฀properties฀and฀ low฀sealing฀ability฀of฀the฀sealants.฀Statistical฀analysis฀using฀ Pearson’s฀chi-square฀test฀indicated฀a฀significant฀difference฀ between฀groups฀1฀(control฀group)฀and฀3฀(P=0.02),฀as฀well฀as฀ with฀group฀4฀(P=.02).

Microleakage฀was฀also฀observed฀on฀the฀intact฀side฀of฀฀ the฀sections.฀Of฀648฀surfaces,฀83฀percent฀(N=538)฀displayed฀

฀฀฀Table฀1. A COMPARISON OF MICROLEAKAGE SCORES AMONG FOUR STUDY GROUPS (SURFACES)฀

Variables N Score฀0*

N฀(%)

Score฀1*

N฀(%)

Score฀2*

N฀(%)

Score฀3*

N฀(%)

Group฀1†_฀

Prophy,฀etch,฀and฀curing฀(10฀s) 162 119฀(74) 12฀(7) 11฀(7) 20฀(12)

Group฀2†

Prophy,฀etch,฀bonding,฀and฀curing฀(10฀s) 162 131฀(81) 4(3) 10฀(6) 17฀(11)

Group฀3‡

Prophy,฀etch,฀and฀curing฀(5฀s) 162 107฀(66) 9฀(6) 6฀(4) 40฀(25)

Group฀4†

Prophy,฀etch,฀and฀curing฀(20฀s) 162 124฀(77) 9฀(6) 10฀(6) 19฀(12)

*฀Score฀0=no฀dye฀penetration;฀1=dye฀penetration฀into฀the฀occlusal฀third฀of฀the฀interface;฀2=dye฀penetration฀into฀the฀middle฀third฀of฀the฀interface;฀3=dye฀penetration฀into฀฀ ฀฀฀the฀apical฀third฀of฀the฀interface.

†฀These฀groups฀are฀not฀statistically฀different฀from฀each฀other฀(chi-square,฀P>.05).

no฀microleakage฀(score฀0).฀Sixty-six฀surfaces฀(10%)฀showed฀฀ severe฀microleakage฀(score฀3),฀and฀minimal฀microleakage฀฀ (score฀1)฀was฀seen฀in฀15฀of฀the฀samples฀(2%).฀Statistical฀ana-฀ lysis฀using฀the฀chi-square฀test฀indicated฀a฀significant฀dif-ference฀between฀the฀repaired฀and฀the฀intact฀(nonrepaired)฀฀ sides฀(P=.001).

Intra-examiner฀ reliability฀ was฀ carried฀ out฀ after฀ the฀฀ second-time฀scoring฀stage,฀and฀Cohen’s฀kappa฀value฀was฀฀ 0.62.฀The฀kappa฀values฀were฀interpreted฀using฀Altman15_฀฀

classifications.฀There฀was฀good฀inter-examiner฀agreement฀ for฀the฀scoring฀of฀microleakage.

Discussion

The฀caries-preventive฀effect฀of฀pit฀and฀fissure฀sealant฀has฀ been฀well฀documented.1-3,7_{฀Meticulous฀application฀proce-฀}

dures฀have฀resulted฀in฀high฀retention฀rates฀and฀high฀in฀ vitro฀bond฀strengths.16฀_{Sealant฀retention฀and฀integrity฀of฀฀}

the฀enamel-sealant฀interface฀determine,฀to฀a฀great฀extent,฀฀ the฀caries฀reduction฀ability฀and฀effectiveness฀of฀a฀resin-filled฀ fissure฀sealant.17

In฀vitro฀microleakage฀tests฀carried฀out฀with฀dyes฀are฀ considered฀stricter฀than฀those฀performed฀in฀the฀oral฀cavity.18฀

This฀is฀most฀likely฀due฀to฀several฀factors฀such฀as฀the฀dye฀ being฀ more฀ easily฀ diffused฀ than฀ bacteria฀ and฀ their฀ by-฀ products฀and฀the฀fact฀that฀buildup฀of฀proteins฀in฀the฀mar-฀ ginal฀opening/gap฀may฀improve฀the฀seal.19_{฀On฀this฀basis,฀}

if฀a฀material฀responds฀positively฀to฀the฀dye฀tests,฀it฀is฀likely฀ to฀respond฀even฀better฀on฀a฀clinical฀level.20

The฀penetration฀of฀a฀dye,฀although฀not฀an฀absolute฀ measure,฀can฀indicate฀the฀lack฀of฀a฀perfect฀seal.฀Within฀ its฀known฀limitations,฀it฀should฀be฀viewed฀as฀a฀theoretical฀ level฀of฀leakage,฀whichmay฀occur฀in฀vivo฀and฀can฀be฀ac-฀ cepted฀as฀an฀aid฀for฀developmental฀purposes.21

The฀use฀of฀a฀prophylaxis฀brush฀followed฀by฀acid฀et-of฀applications.10,22_฀

In฀ this฀ study,฀ a฀ new฀ generation฀ of฀ dentin-bonding฀฀ agent฀was฀selected,฀Adper฀Single฀Bond฀2฀Adhesive฀(fifth-generation),฀which฀offers฀the฀dental฀practitioner฀a฀wide฀฀ range฀of฀applications,฀and฀can฀be฀used฀both฀in฀moist฀and฀฀ dry฀conditions.฀It฀was฀used฀as฀an฀intermediary฀layer฀be-฀ tween฀ 2฀ layers฀ of฀ the฀ same฀ materials฀ (Filtek฀ Z350,฀3M฀฀ ESPE,฀USA)฀and฀found฀to฀be฀slightly฀better฀than฀the฀sam-฀ ples฀ repaired฀ without฀ a฀ bonding฀ agent,฀ but฀ it฀ was฀ not฀฀ statistically฀different.

Some฀authors฀have฀reported฀that฀the฀use฀of฀a฀dentin-bonding฀ agent฀ under฀ sealant฀ as฀ an฀ intermediate฀ layer฀฀ significantly฀ decreased฀ microleakage฀ on฀ contaminated฀฀ enamel฀or฀in฀ideal฀conditions฀when฀there฀was฀no฀contami-nation.22,23_{฀These฀results฀were฀not฀achieved฀by฀this฀study.฀฀}

Previous฀studies,฀however,฀have฀reported฀the฀use฀of฀a฀bond-฀ ing฀agent฀under฀sealant฀on฀wet฀contaminated฀enamel฀and฀฀ using฀a฀conventional฀halogen฀curing฀unit,฀which฀could฀฀ have฀attributed฀to฀the฀contradictory฀results.

This฀study’s฀results฀are฀similar฀to฀the฀findings฀of฀an฀in฀ vitro฀study฀by฀Sirinivasan฀et฀al,13_{฀in฀which฀they฀compared฀}

the฀microleakage฀of฀pit฀and฀fissure฀sealants฀applied฀with฀฀ leakage.฀These฀results฀agree฀with฀Silta฀et฀al24_{฀and฀Swanson฀฀}

et฀al25_{฀studies,฀in฀which฀the฀longer฀curing฀time฀(10฀and฀20฀}

seconds)฀resulted฀a฀significant฀reduction฀in฀microleakage. study฀ by฀ Srinivasan฀ et฀ al,13_{฀ yet฀ lower฀ than฀ a฀ study฀ by฀฀}

Blackwood฀et฀al,26_{฀that฀investigated฀microleakage฀of฀fissure฀฀}

sealants.฀Although฀the฀reliability฀is฀lower฀than฀hoped,฀it฀฀ still฀represents฀an฀acceptable฀level.

Flowable฀composites฀offer฀an฀additional฀alternative฀฀ among฀tooth-colored฀restorative฀materials.฀Their฀viscosity,฀ consistency,฀handling฀characteristics,฀delivery฀system,฀and฀ multiple฀uses฀make฀flowable฀filled฀resins฀a฀very฀attractive฀฀ choice฀and฀a฀popular฀addition฀to฀the฀dentist’s฀armamenta-฀ rium.฀It฀has฀been฀reported฀that฀flowable฀filled฀resins฀de-monstrate฀resistance฀to฀microleakage฀in฀both฀enamel฀and฀ cementum/dentin฀margins฀similar฀to฀hybrid฀composites.27

This฀study฀did฀not฀incorporate฀the฀use฀of฀pumice฀or฀฀ any฀prophylaxis฀paste,฀as฀it฀has฀been฀reported฀that฀remain-ing฀ debris฀ comprisany฀prophylaxis฀paste,฀as฀it฀has฀been฀reported฀that฀remain-ing฀ pellicle฀ and฀ pumice฀ can฀ still฀ re-฀ main฀ deep฀ within฀ fissures,฀ even฀ after฀ prophylaxis฀ and฀฀ etching.7,28_{฀Therefore,฀it฀is฀presumed฀that฀the฀presence฀of฀฀}

the฀pumice฀or฀prophylaxis฀paste฀can฀prevent฀the฀penetra-฀ tion฀of฀the฀etchant฀into฀the฀fissure’s฀depth,฀thereby฀reducing฀฀ the฀available฀etched฀substrate฀to฀be฀infiltrated฀by฀the฀flow-฀ able฀sealant.

To฀mimic฀sealant฀failure,฀it฀is฀necessary฀either฀to฀dupli-฀ cate฀the฀effect฀of฀salivary฀contamination฀during฀etching,฀฀ which฀was฀rejected฀because฀of฀standardization฀difficulties,13฀

or฀to฀mimic฀failure฀on฀the฀enamel฀surface฀itself฀by฀avoiding฀฀ any฀previous฀roughening.฀The฀latter฀may฀include฀mimick-฀ ing฀ more฀ than฀ one฀ cause฀ of฀ sealant฀ failure,฀ other฀ than฀฀ salivary฀contamination,฀such฀as฀prismless฀enamel,฀salivary฀ contamination฀during฀etching,฀and฀different฀nature฀of฀ena-฀ mel฀surfaces.9,29฀_{Therefore฀enamel฀surfaces฀did฀not฀have฀any฀}

previous฀roughening.฀Placing฀a฀small฀spoon฀excavator฀in฀฀ the฀untreated฀half฀of฀the฀occlusal฀surface฀facilitated฀easy฀฀ removal฀of฀the฀sealant฀from฀the฀unetched฀part฀of฀all฀the฀ samples.฀

In฀this฀experiment,฀attempts฀were฀made฀to฀simulate฀฀ the฀oral฀environment฀and฀standard฀clinical฀procedures฀by฀ choosing฀intact฀freshly฀extracted฀human฀molars฀with฀pro-minent฀cusps฀and฀storing฀the฀teeth฀in฀0.12฀percent฀thymol.฀฀ The฀sealed฀teeth฀were฀immersed฀in฀artificial฀saliva฀twice฀for฀฀ a฀total฀of฀2฀weeks฀and฀immersed฀in฀methylene฀blue฀dye฀at฀฀ 37°C฀with฀a฀pH฀of฀7฀for฀48฀hours.฀In฀the฀composite฀repair฀ scenario,฀these฀stages฀or฀factors฀are฀of฀primary฀importance.฀฀ It฀has฀been฀suggested฀that฀the฀greatest฀reactivity฀of฀the฀com-posite฀surface฀to฀the฀formation฀of฀covalent฀bonds฀with฀a฀฀ fresh฀resin฀composite฀can฀be฀found฀during฀the฀first฀24฀hours฀ after฀polymerization,30_{฀but฀this฀reactivity฀tends฀to฀decrease฀}

with฀time.31_{฀The฀1-week฀waiting฀period฀after฀repair฀is฀also฀}

considered฀a฀factor฀that฀may฀have฀an฀effect฀on฀the฀composite-to-composite฀bond.฀This,฀in฀addition฀to฀the฀salivary฀activity,฀ has฀shown฀to฀accelerate฀the฀biodegradation฀of฀composite฀฀ resins฀and฀interfacial฀couplings.32

One฀limitation฀of฀this฀study฀was฀the฀difficulty฀to฀stan-dardize฀the฀size฀or฀shape฀of฀the฀broken฀part฀of฀the฀fissure฀฀ sealant฀between฀different฀teeth฀and,฀hence,฀different฀groups.

The฀present฀data฀didn’t฀demonstrate฀any฀single฀method฀ of฀repair฀to฀be฀superior฀to฀the฀control฀method.฀The฀worst฀

microleakage฀scores฀occurred฀in฀group฀3.฀We฀would฀be฀ reluctant฀to฀suggest฀further฀research฀and฀clinical฀studies฀in฀฀ this฀area฀to฀identify฀the฀most฀efficient฀method฀of฀repairing฀ a฀fractured฀fissure฀sealant.฀It฀may฀be฀concluded฀that฀micro-leakage฀is฀still฀a฀reality฀with฀the฀present฀nano-filled฀resin-฀ based฀adhesive฀system฀and฀the฀recently฀introduced฀LED฀฀ curing฀devices,฀irrespective฀of฀whether฀it฀is฀the฀first฀appli-฀ cation฀or฀a฀repair฀or฀resealing฀over฀a฀fractured฀sealant.฀The฀฀ LED฀curing฀unit฀used฀in฀this฀study฀may฀reduce฀the฀curing฀ time฀by฀one฀half,฀as฀there฀was฀no฀significant฀difference฀in฀ microleakage฀between฀10฀and฀20฀seconds฀curing฀time.

Conclusions

Based฀on฀this฀study’s฀results,฀the฀following฀conclusions฀can฀ be฀made:

1.฀ Prophylaxis฀with฀a฀brush,฀followed฀by฀acid฀etching฀ and฀an฀LED฀light฀curing฀for฀10฀seconds,฀seems฀to฀ be฀the฀simplest฀and฀the฀most฀appropriate฀method฀฀ of฀repairing฀fractured฀nano-filled฀resin฀sealants. 2.฀ Under฀this฀study’s฀conditions,฀the฀length฀of฀the฀

curing฀time฀is฀significantly฀related฀to฀the฀degree฀of฀ microleakage.

3.฀ The฀LED฀curing฀unit฀used฀in฀this฀study฀may฀reduce฀ the฀curing฀time.

References

฀ 1.฀ Locker฀D,฀Jokovic฀A,฀Kay฀EJ.฀Prevention.฀Part฀8:฀The฀ use฀of฀pit฀and฀fissure฀sealants฀in฀preventing฀caries฀in฀฀ the฀permanent฀dentition฀of฀children.฀Br฀Dent฀J฀2003;฀ 195(7):375-8.

฀ 2.฀ Papacchini฀ F,฀ Goracci฀ C,฀ Sadek฀ FT,฀ Monticelli฀ F,฀฀ Garcia-Godoy฀F,฀Ferrari฀M.฀Microtensile฀bond฀strength฀ to฀ground฀enamel฀by฀glass฀ionomers,฀resin-modified฀ glass-ionomers,฀and฀resin฀composites฀used฀as฀pit฀and฀ fissure฀sealants.฀J฀Dent฀2005;33:459-67.

฀ 3.฀ Ripa฀LW.฀Sealants฀revisited:฀An฀update฀of฀the฀effec-tive-ness฀of฀pit-and-fissure฀sealants.฀Caries฀Res฀1993;27฀ (suppl฀1):77-82.

฀ 4.฀ Mertz-Fairhurst฀EJ,฀Smith฀CD,฀Williams฀JE,฀Sherrer฀ JD,฀Mackert฀JR฀Jr,฀Richards฀EE,฀et฀al.฀Cariostatic฀and฀ ultraconservative฀sealed฀restorations:฀Six-year฀results.฀ Quintessence฀Int฀1992;23:827-38.

฀ 5.฀ Simonsen฀RJ.฀Retention฀and฀effectiveness฀of฀dental฀฀ sealant฀after฀15฀years.฀J฀Am฀Dent฀Assoc฀1991;122:฀ 34-42.

฀ 6.฀ McDonald฀RE,฀Avery฀DR,฀Dean฀JA.฀Dentistry฀for฀the฀

Child฀and฀Adolescent.฀8th_{฀ed.฀St.฀Louis,฀Mo:฀Mosby;฀}

2004.

฀ 7.฀ Feigal฀RJ.฀Sealants฀and฀preventive฀restorations:฀Review฀ of฀ effectiveness฀ and฀ clinical฀ changes฀ for฀ improve-฀ ment.฀Pediatr฀Dent฀1998;20:85-92.

฀ 8.฀ Feigal฀RJ.฀The฀use฀of฀pit฀and฀fissure฀sealants.฀Pediatr฀฀ Dent฀2002;24:415-22.

฀ 9.฀ Celiberti฀P,฀Lussi฀A.฀Use฀of฀a฀self-etching฀adhesive฀ on฀previously฀etched฀intact฀enamel฀and฀its฀effect฀on฀฀ sealant฀microleakage฀and฀tag฀formation.฀J฀Dent฀2005;฀ 33:163-71.

฀10.฀ Hitt฀JC,฀Feigal฀RJ.฀Use฀of฀a฀bonding฀agent฀to฀reduce฀ sealant฀sensitivity฀to฀moisture฀contamination:฀An฀in฀฀ vitro฀study.฀Pediatr฀Dent฀1992;14:41-6.

฀11.฀ Nunn฀JH,฀Murray฀JJ,฀Smallridge฀J.฀British฀Society฀of฀ Paediatric฀Dentistry:฀A฀policy฀document฀on฀fissure฀seal-฀ ants฀in฀paediatric฀dentistry.฀Int฀J฀Paediatr฀Dent฀2000;฀ 10:174-7.

฀12.฀ Welbury฀R,฀Raadal฀M,฀Lygidakis฀NA.฀EAPD฀guidelines฀ for฀the฀use฀of฀pit฀and฀fissure฀sealants.฀Eur฀J฀Paediatr฀฀ Dent฀2004;5:179-84.

฀13.฀ Srinivasan฀V,฀Deery฀C,฀Nugent฀Z.฀In฀vitro฀microleakage฀ of฀repaired฀fissure฀sealants:฀A฀randomized,฀controlled฀฀ trial.฀Int฀J฀Paediatr฀Dent฀2005;15:51-60.

฀14.฀ Dupont฀WD,฀Plummer฀WD.฀PS฀power฀and฀sample฀ size฀program.฀Available฀at:฀“http://www.mc.vanderbilt. edu/prevmed/ps.htm”.฀Accessed฀January฀18,฀2007. ฀15.฀ Altman฀DG.฀Practical฀Statistics฀for฀Medical฀Research.฀

London,฀UK:฀Chapman฀and฀Hall;฀1999.

฀16.฀ Ansari฀G,฀Oloomi฀K,฀Eslami฀B.฀Microleakage฀assess-ment฀of฀pit฀and฀fissure฀sealant฀with฀and฀without฀the฀฀ use฀of฀pumice฀prophylaxis.฀Int฀J฀Paediatr฀Dent฀2004;฀ 14:272-8.

฀17.฀ Hannig฀M,฀Grafe฀A,฀Atalay฀S,฀Bott฀B.฀Microleakage฀ and฀SEM฀evaluation฀of฀fissure฀sealants฀placed฀by฀use฀฀ of฀self-etching฀priming฀agents.฀J฀Dent฀2004;32:75-81. ฀18.฀ Jacobs฀MS,฀Windeler฀AS.฀An฀investigation฀of฀dental฀lu-฀

ting฀cement฀solubility฀as฀a฀function฀of฀the฀marginal฀฀ gap.฀J฀Prosthet฀Dent฀1991;65:436-42.

฀19.฀ Baldissara฀P,฀Comin฀G,฀Martone฀F,฀Scotti฀R.฀Compara-฀ tive฀study฀of฀the฀marginal฀microleakage฀of฀six฀cements฀฀ in฀fixed฀provisional฀crowns.฀J฀Prosthet฀Dent฀1998;80:฀ 417-22.

฀20.฀ Pashley฀DH.฀Clinical฀considerations฀of฀microleakage.฀J฀ Endod฀1990;16:70-7.

฀21.฀ Salama฀FS,฀Al-Hammad฀NS.฀Marginal฀seal฀of฀sealant฀฀ and฀compomer฀materials฀with฀and฀without฀enamelo-plasty.฀Int฀J฀Paediatr฀Dent฀2002;12:39-46.

฀22.฀ Tulunoglu฀O,฀Bodur฀H,฀Uctasli฀M,฀Alacam฀A.฀The฀ effect฀of฀bonding฀agents฀on฀the฀microleakage฀and฀bond฀฀ strength฀of฀sealant฀in฀primary฀teeth.฀J฀Oral฀Rehabil฀1999;฀ 26:436-41.

฀23.฀ Borem฀LM,฀Feigal฀RJ.฀Reducing฀microleakage฀of฀seal-฀ ants฀under฀salivary฀contamination:฀Digital฀image฀ana-฀ lysis฀evaluation.฀Quintessence฀Int฀1994;25:283-9. ฀24.฀ Silta฀ YT,฀ Dunn฀ WJ,฀ Peters฀ CB.฀ Effect฀ of฀ shorter฀

polymerization฀times฀when฀using฀the฀latest฀generation฀ of฀light-emitting฀diodes.฀Am฀J฀Orthod฀Dentofacial฀฀ Orthop฀2005;128:744-8.

฀25.฀ Swanson฀T,฀Dunn฀WJ,฀Childers฀DE,฀Taloumis฀LJ.฀Shear฀ bond฀strength฀of฀orthodontic฀brackets฀bonded฀with฀฀ light-emitting฀diode฀curing฀units฀at฀various฀polymeri-zation฀times.฀Am฀J฀Orthod฀Dentofacial฀Orthop฀2004;฀ 125:337-41.

฀26.฀ Blackwood฀JA,฀Dilley฀DC,฀Roberts฀MW,฀Swift฀EJ฀Jr.฀ Evaluation฀of฀pumice,฀fissure฀enameloplasty,฀and฀air฀ abrasion฀on฀sealant฀microleakage.฀Pediatr฀Dent฀2002;฀ 24:199-203.

฀27.฀ Attar฀N,฀Korkmaz฀Y.฀Effect฀of฀two฀light-emitting฀diode฀ (LED)฀and฀one฀halogen฀curing฀light฀on฀the฀microleakage฀ of฀Class฀V฀flowable฀composite฀restorations.฀J฀Contemp฀ Dent฀Pract฀2007;8:80-8.

฀28.฀ Burrow฀MF,฀Makinson฀OF.฀Pits฀and฀fissures:฀Remnant฀ organic฀debris฀after฀acid-etching.฀J฀Dent฀Child฀1990;฀ 57:348-51.฀

฀29.฀ Feldens฀EG,฀Feldens฀CA,฀de฀Araujo฀FB,฀Souza฀MA.฀ Invasive฀technique฀of฀pit฀and฀fissure฀sealants฀in฀primary฀ molars:฀A฀SEM฀study.฀J฀Clin฀Pediatr฀Dent฀1994;18:฀ 187-90.

฀30.฀ Saunders฀WP.฀Effect฀of฀fatigue฀upon฀the฀interfacial฀bond฀ strength฀of฀repaired฀composite฀resins.฀J฀Dent฀1990;18:฀ 158-62.

฀31.฀ Burtscher฀P.฀Stability฀of฀radicals฀in฀cured฀composite฀ materials.฀Dent฀Mater฀1993;9:218-21.