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Vesna MileticVesna Miletic1,21,2, Ario Santini, Ario Santini11
1 1 The University of Edinburgh, Edinburgh Postgraduate Dental Institute, The University of Edinburgh, Edinburgh Postgraduate Dental Institute, United KingdomUnited Kingdom2 2 University of Belgrade, School of Dentistry, SerbiaUniversity of Belgrade, School of Dentistry, Serbia
Effect of preparation and storage Effect of preparation and storage on adhesive monomer conversionon adhesive monomer conversion
Studies investigating the degree of conversion (DC) of Studies investigating the degree of conversion (DC) of adhesives - samples prepared in a variety of waysadhesives - samples prepared in a variety of ways
Substrates such as potassium-bromide pellet/crystal, acetate Substrates such as potassium-bromide pellet/crystal, acetate strips, glass slides or dentine discsstrips, glass slides or dentine discs
Light curing with or without the use of a Mylar strip covering Light curing with or without the use of a Mylar strip covering
Variations in storage parameters such as time, temperature, Variations in storage parameters such as time, temperature, humidity and mediahumidity and media
INTRODUCTION
To study the effect of preparation and To study the effect of preparation and
storage conditions on the DC of storage conditions on the DC of
two adhesive systems using two adhesive systems using
micro-Raman spectroscopy. micro-Raman spectroscopy.
OBJECTIVEOBJECTIVE
Sample preparation:Sample preparation:
Etch-and-rinse (Excite, Etch-and-rinse (Excite, Ivoclar VivadentIvoclar Vivadent) )
and self-etch adhesive (Clearfil 3S, and self-etch adhesive (Clearfil 3S, KurarayKuraray) )
n=5n=5
Glass slides vs. Dentine discsGlass slides vs. Dentine discs
Mylar strip covering vs. No Mylar strip coveringMylar strip covering vs. No Mylar strip covering
LED light (bluephase, LED light (bluephase, Ivoclar VivadentIvoclar Vivadent) intensity 650 mW/cm) intensity 650 mW/cm22, 10 s curing , 10 s curing time, 1 mm distancetime, 1 mm distance
MATERIALS AND METHODS
Sample preparation:Sample preparation:
Etch-and-rinse (Excite, Etch-and-rinse (Excite, Ivoclar VivadentIvoclar Vivadent) )
and self-etch adhesive (Clearfil 3S, and self-etch adhesive (Clearfil 3S, KurarayKuraray) )
n=5n=5
Glass slides vs. Dentine discsGlass slides vs. Dentine discs
Mylar strip covering vs. No Mylar strip coveringMylar strip covering vs. No Mylar strip covering
LED light (bluephase, LED light (bluephase, Ivoclar VivadentIvoclar Vivadent) intensity 650 mW/cm) intensity 650 mW/cm22, 10 s curing , 10 s curing time, 1 mm distancetime, 1 mm distance
MATERIALS AND METHODS
Micro-Raman spectroscopy Micro-Raman spectroscopy (5 min post-curing, 3 random spectra per sample, top surface)(5 min post-curing, 3 random spectra per sample, top surface)
MATERIALS AND METHODSMATERIALS AND METHODS
DC=[1-Rcured / Runcured] x 100
Storage conditions:Storage conditions:
Adhesives: Excite and Clearfil3S (n=5)Adhesives: Excite and Clearfil3S (n=5)
Glass slides / Dentine discsGlass slides / Dentine discs
Mylar strip coveringMylar strip covering
LED light (bluephase) intensity 650 mW/cmLED light (bluephase) intensity 650 mW/cm22, 10 s curing time, 1 mm , 10 s curing time, 1 mm distancedistance
Micro-Raman spectroscopy 5 min post-curing and after storageMicro-Raman spectroscopy 5 min post-curing and after storage
MATERIALS AND METHODSMATERIALS AND METHODS
Storage conditions (24 hours)Storage conditions (24 hours)
Group I (22±2ºC and 45±3% humidity) - Group I (22±2ºC and 45±3% humidity) - light proof container, laboratory benchlight proof container, laboratory bench
Group II (37±1ºC and 90±2% humidity) -Group II (37±1ºC and 90±2% humidity) -light proof container with side openings, water bath with punched light proof container with side openings, water bath with punched aluminum foil coveraluminum foil cover
Group III (distilled water at 37±1ºC) -Group III (distilled water at 37±1ºC) -glass vial, 1 ml distilled water, covered water bath glass vial, 1 ml distilled water, covered water bath
Group IV (artificial saliva at 37±1ºC) - Group IV (artificial saliva at 37±1ºC) - glass vial, 1 ml artificial saliva, covered water bath glass vial, 1 ml artificial saliva, covered water bath
MATERIALS AND METHODSMATERIALS AND METHODS
StatisticsStatistics
ANOVA and repeated measures ANOVAANOVA and repeated measures ANOVA
t testt test
significance level significance level αα=0.05=0.05
MATERIALS AND METHODSMATERIALS AND METHODS
Sample preparation - Excite
70.3
22.9
71.6
42.2
0
20
40
60
80
100
Glass, w/Mylar
Glass, w/oMylar
Dentine, w/Mylar
Dentine,w/o Mylar
Preparation method
De
gre
e o
f c
on
ve
rsio
n
(%)
RESULTS
Sample preparation - Clearfil 3S
50.0 45.3
80.270.7
0
20
40
60
80
100
Glass, w/Mylar Glass, w/o Mylar Dentine, w/ Mylar Dentine, w/o Mylar
Preparation method
Deg
ree
of c
on
vers
ion
(%
)
Sample storage Sample storage -- Excite - Excite - Glass slides Glass slides
Groups: high humidity, distilled water and artificial saliva => sample Groups: high humidity, distilled water and artificial saliva => sample deformation, impossible to obtain micro-Raman spectra from the top deformation, impossible to obtain micro-Raman spectra from the top surfacesurface
Group stored at 22±2ºC and 45±3% humidityGroup stored at 22±2ºC and 45±3% humidity
Before: DC=70.8%(1.7%)Before: DC=70.8%(1.7%)
After: DC=73.6%(1.8%) After: DC=73.6%(1.8%)
[paired t-test, p<0.05][paired t-test, p<0.05]
RESULTS
Sample storage Sample storage -- Clearfil 3S - Clearfil 3S - Glass slidesGlass slides
78.5 86.3
50.2 51.2
0
20
40
60
80
100
Before After Before After
22ºC, 45% humidity 37ºC, 90% humidity
Storage conditions
De
gre
e o
f c
on
ve
rsio
n
(%)
Group 1 Group 2
RESULTS
• Group 1: p<0.001• Group 2: p<0.001• Group 1 vs. Group 2 (before): p=0.208• Group 1 vs. Group 2 (after): p<0.001[t-test]
Sample storage Sample storage -- Excite - Excite - Dentine discsDentine discs
78.970.4 73.4 70.9 73.7 72.3 70.7
90.2
0
20
40
60
80
100
Before After Before After Before After Before After
22ºC, 45%humidity
37ºC, 90%humidity
37ºC, dist.water
37ºC, BIM
Storage conditions
De
gre
e o
f c
on
ve
rsio
n (
%) Group 1 Group 2 Group 3 Group 4
RESULTS
Before vs. After • Group 1: p=0.002• Group 2: p=0.007• Group 3: p<0.001• Group 4: p<0.001[repeated measures ANOVA and paired t test]
Sample storage Sample storage -- Clearfil 3S - Clearfil 3S - Dentine discsDentine discs
Repeated measures ANOVA Repeated measures ANOVA Factor “Medium”: p=0.507Factor “Medium”: p=0.507 Factor “Time”: p<0.001Factor “Time”: p<0.001 Interaction “Medium” x “Time”: p=0.190Interaction “Medium” x “Time”: p=0.190
79.788.9
79.189.2
80.389.9
79.592.5
020406080
100
Before After Before After Before After Before After
22ºC, 45%humidity
37ºC, 90%humidity
37ºC, dist. water 37ºC, BIM
Storage conditions
De
gre
e o
f c
on
ve
rsio
n (
%)RESULTS
Sample preparation and storage significantly affected the DC of the etch-and-rinse and self-etch adhesive
Differences in the effect of both preparation and storage were observed for the two adhesives
Oxygen inhibition on the adhesive surface was significantly reduced using Mylar strips
“Dark” cure during storage increased the initial DC due to consumption of C=C double bonds
Compared to storage in air, liquid media further increased the DC, most likely due to elution of monomers
CONCLUSIONS
Variables such as oxygen inhibition and elution should be eliminated as they do not represent the DC of the adhesive polymer
Non-dental models may be appropriate for comparing e.g. effects of curing lights/curing times on conversion but not for material comparison since the results may not be clinically relevant
CONCLUSIONS
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