Microleakage Assessment of a Repaired Na

PEDIATRIC DENTISTRY

V 31 / NO 5

SEP / OC T 09

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, MFDS2 • Dasmawati Mohamad, BEng Chem Eng, MSc, PhD3

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฀fermentable฀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฀deterioration฀of฀the฀material—increasing฀the฀possibility฀of฀develo-฀
ping฀caries฀and,฀thus,฀interfering฀in฀the฀long-term฀success฀฀

of฀the฀technique.
1Dr. Qadri is is a Paediatric Dentist, and 2Dr. Noor is a lecturer, both in the Paediatric

฀

Dentistry Unit, and 3Dr. Mohamad is a lecturer in a Biomaterials Unit, all in the School
of Dental Sciences, University Science Malaysia, Health Campus, Kelantan, Malaysia.
Correspond with Dr. Qadri at al_qadry@yahoo.com

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฀฀

REPAIRING A FRAC TURED FISSURE SE ALANT

389

PEDIATRIC DENTISTRY

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microleakage;฀and฀determine฀the฀effect฀of฀different฀LED฀฀ teeth฀were฀removed฀from฀the฀artificial฀saliva฀and฀washed฀฀
light฀curing฀times฀on฀microleakage฀of฀a฀repaired฀nano-filled฀ with฀an฀air-water฀spray.฀The฀teeth฀were฀then฀subjected฀to฀1฀฀
resin-based฀fissure฀sealant฀in฀vitro.
of฀the฀following฀techniques฀of฀repair:

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฀manufacturer’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฀(unetched)฀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฀

390

REPAIRING A FRACTURED FISSURE SE ALANT

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.฀
Once฀the฀nail฀varnish฀dried,฀each฀tooth฀was฀placed฀in฀a฀฀
1฀ percent฀ aqueous฀ solution฀ of฀ methylene฀ blue฀ that฀ was฀฀
buffered฀to฀pH฀7฀for฀48฀hours฀inside฀an฀incubator฀(Sanyo,฀฀
Japan)฀at฀37°C.฀The฀teeth฀were฀then฀rinsed฀thoroughly฀in฀฀
tap฀water.฀Each฀tooth฀was฀embedded฀completely฀in฀a฀light฀฀
cured฀ clear฀ acrylic฀ (polymethyl฀ methacrylate)฀ and฀ cured฀
in฀a฀light฀polymerization฀unit฀(Exact,฀Düsseldorf,฀Germany)฀

PEDIATRIC DENTISTRY

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฀watercooled฀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฀penetration฀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.

V 31 / NO 5

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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฀(%)

162

119฀(74)

12฀(7)

11฀(7)

20฀(12)

162

131฀(81)

4(3)

10฀(6)

17฀(11)

162

107฀(66)

9฀(6)

6฀(4)

40฀(25)

162

124฀(77)

9฀(6)

10฀(6)

19฀(12)

Group฀1†฀
Prophy,฀etch,฀and฀curing฀(10฀s)
Group฀2†
Prophy,฀etch,฀bonding,฀and฀curing฀(10฀s)
Group฀3‡
Prophy,฀etch,฀and฀curing฀(5฀s)
Group฀4†
Prophy,฀etch,฀and฀curing฀(20฀s)

*฀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).
‡฀Indicates฀statistically฀significant฀difference฀when฀compared฀with฀group฀1฀(chi-square฀test,฀P