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International Medical Journal Vol. 20, No. 3, pp. 359 - 362 , June 2013
DENTAL SCIENCES
Comparison between Microleakage of Composite and
Porcelain in Class V Restoration: An in vitro Study
Adrian Tay Cheong Ian, Nor Aidaniza Abdul Muttlib, Wan Zaripah Wan Bakar,
Mohammad Khursheed Alam
ABSTRACT
Introduction: Composite resin (CR) undergoes polymerisation shrinkage which caused microleakage leading to marginal
staining and secondary caries. Porcelain is strong and esthetically-favourable but is rarely used in class V restorations. This in
vitro study aims to assess the presence and compare the percentage of microleakage between direct, indirect CR and porcelain
in restoring class V cavity.
Materials and Methods: Class V cavities measuring 4 mm x 3 mm x 2.5 mm depth were prepared on the buccal surfaces of 96
extracted premolar teeth. The teeth were randomly assigned into 3 groups (n = 32) where Group 1 was restored with Filtek
Z350 nanocomposite (3M ESPE, USA), Group 2 were restored with ceramage A3B (SHOFU, Japan) and Group 3 was cemented
with IPS e.max Press all ceramic cervical inlay (Ivoclar-Vivadent, Zurich). All teeth were then subjected to 600 thermocycles
between 5
℃
and 55
℃
before immersion in 2% methylene blue dye for 24 hours. The teeth were sectioned vertically into half by
hard tissue cutter (EXAKT, Germany). Dye penetration depths were measured using Leica imaging system (UK) at 30x magnifi-
cation.
Results: The result shows porcelain cervical inlay group has significantly less microleakage than direct CR group (p = 0.045)
but there is no significant difference compared to indirect CR (p = 0.973). No significant difference was discovered in microleak-
age depth between direct and indirect CR (p = 0.077).
Conclusion: Porcelain cervical inlay could be an alternative in restoring class V cavity for clinicians due to better marginal
seal and aesthetic.
KEY WORDS
microleakage, composite, porcelain, class V cavity, restoration
Received on June 8, 2012 and accepted on September 10, 2012
School of Dental Sciences, Universiti Sains Malaysia
Correspondence to: Nor Aidaniza Abdul Muttlib
(e-mail: aidaniza@kb.usm.my)
359
INTRODUCTION
A class V cavity is defined as a cavity which involves the cervi-
cal third of facial or lingual surface of an anterior or posterior tooth.
In our clinical practice, we usually come across patients with caries
on the buccal surface of their posterior teeth, especially the molar
teeth and composite resin has been our primary choice of restorative
dental material for such cavities. However, direct composite is tech-
nique and moisture-sensitive, and as such it has a low success rate
(Major and Toffenetti 1992, Cavalcanti et. al. 2008). It also can cause
marginal leakage due to polymerization shrinkage (Salwa K and
Khamis H 2005). In the long term, secondary caries and sensitivity of
restored teeth may occur, necessitating the need for replacement of
the composite resin (Kidd et. al. 1992, Major and Toffenetti 1992).
Porcelain on the other hand is increasing in popularity among
dental practitioners due to its excellent aesthetic value, good strength
and border sealing with low thermal volume changes in filling (John
et.al. 1992). In terms of aesthetic appeal, it does not wear down easi-
ly and the color easily camouflages with the natural tooth color (John
et. al. 1992). In addition, there is less chances of microleakage with
the thermal conductivity and coefficient of thermal expansion being
almost similar to enamel and dentine (Versluis et. al. 1996).
Indirect composite can be another alternative to direct composite
as it has a better control of marginal fit, matching color and less poly-
merization as compared with direct composite (Deng et. al. 2009,
Brochure of ceramage, Shofu). Moreover, indirect composite is easier
to repair, less abrasive and costly and has a simpler laboratory proce-
dure compared to porcelain (Deng et. al.2009, Brochure of ceramage,
Shofu). Moreover, both materials require the same restorative and
luting agent (Deng et. al. 2009).
Based on the aforementioned advantages of indirect composite
and porcelain, it would thus be beneficial to explore the incidence of
microleakage of class V restoration for both materials with direct
composite in vitro study and determine their viability as treatment
options for class V caries lesion in the future.
MATERIALS AND METHODS
Specimen Preparation
Ninety six sound extracted human molars were selected to be
used in this study. The teeth were cleaned with ultrasonic scaler
(Piezon Systems, EMS, Switzerland) and stored in normal saline at
room temperature. Standardized class V cavities (4 mm width x 3
mm height x 2.5 mm depth) were prepared on the buccal surfaces
where gingival margins were located 1mm above cementoenamel
C 2013 Japan International Cultural Exchange Foundation
& Japan Health Sciences University
360
Cheong Ian A. T. et al.
Figure 1. Schematic diagram of cavity preparation on a sound molar tooth
Table 1. Numbers of teeth with the percentage of dye penetration at margin
Group Score
0% 10-20% 20-30% 30-40% 40-50% 50-60% 60-70% 70-80% 80-90% 90-100%
Flitek Z350 0 0 0 0 1 3 1 3 7 17
Ceramage 0 0 1 0 3 3 7 1 4 13
A3B
Porcelain 0 0 0 1 2 4 3 10 2 10
Table 3. Post Hoc test- Tukey
(I) method (J) method Mean Std. Error Sig. 95% Confidence Interval
Difference (I-J) Lower Bound Upper Bound
direct composite indirect composite 10.50154 4.77442 .077 -.8702 21.8733
indirect composite porcelain 1.06421 4.77442 .973 -10.3076 12.4360
porcelain direct composite -11.56575* 4.77442 .045 -22.9375 -.1940
* p = 0.05
Table 2. Compare percentage of microleakage using One-way ANOVA
Sum of Squares df Mean Square F Sig.
Between Groups 2615.268 2 1307.634 3.585 .032
Within Groups 33919.130 93 364.722
Total 36534.398 95
*p < 0.05 is considered to be significant
361
junction. All cavity preparations were done by single calibrated oper-
ator using flat fissure bur (Hager & Meisinger GmbH, Germany) at a
high-speed handpiece under water cooling. Each bur was limited to
prepare four cavities only to avoid dullness.
Restorative procedures
The prepared teeth are randomly divided into three groups of 32
each. The same calibrated operator performed all restorative proce-
dures. The cavities were restored with 3 different restorative materi-
als; group I were restored with Filtek Z350 (3M ESPE, USA), group
II were restored with ceramage (A3B SHOFU, Japan) and group III
were cemented with IPS e.max Press porcelain cervical veneer
(Ivoclar Vivadent, Switzerland).
For teeth in group I, the cavity was etched with 35% phosphoric
acid (Scotchbond Etchant, 3M ESPE, USA) for 15s. The acid was
rinsed with water spray for 15s, and excess moisture was removed
with cotton pellet. Adper Single Bond 2 Adhesive (3M ESPE, USA)
was applied according to manufacturer's instruction before light
cured for 10 seconds. They were filled incrementally with Filtek
Z350, Shade A3 (3M ESPE, USA) then light cured for 20 seconds on
each increment. The light-curing unit was calibrated at 500 mW/cm
2
and the curing tip was positioned at a distance of 1 mm from surface
of each restorations. Polishing was done after 24 hours using Sof-Lex
discs (3M ESPE, USA) from medium to fine grade.
For group II, ceramage (A3B, SHOFU, Japan) were incremental-
ly applied and light cured for 10s. The final increments were placed
slightly in excess and were light cured (Solidilite, Shofu, Japan) for 3
minute. The cavity was etched with 35% phosphoric acid
(Scotchbond Etchant, 3M ESPE, USA) for 15s. The acid was rinsed
with water spray for 15s, and excess moisture was removed with cot-
ton pellet. RelyX U100 (3M ESPE, USA) were applied according to
manufacturer's instructions to the cavity and the base of the inlay.
The inlay was firmly stabilized in the cavity and excess cement was
removed. After 24 hours, the restorations were polished and finished
with Sof-Lex discs (3M ESPE, USA) from medium to fine grade.
For teeth in group III, the waxed up was done for the cavities and
investing was carried out with IPS PressVEST Speed (Ivoclar,
Switzeland) according to the manufacturer's instructions. The cold
IPS e.max Press ingot with low translucency A1 (Ivoclar Vivadent,
Switzeland) was used in the IPS Empress - EP 600 press furnace
(Ivoclar Vivadent, Switzeland). The selected press program was start-
ed according to manufacturer's recommended parameters and then
divested to produce the porcelain cervical veneer.
For the cementation of the porcelain cervical veneer, the cavity
was dried with cotton pellet, acid etched with porcelain etchant, 5%
hydrofluoric acid (Ultradent, USA) for 15 seconds followed by rins-
ing with water for 15 seconds and dried with cotton pellet. Silane
(Ultradent, USA) was applied on the fitting surface of the porcelain
cervical veneer before cementing with RelyX U100 (3M ESPE, USA)
according to manufacturer's instructions.
Assessment Procedure
The restored teeth were stored in distill water at room tempera-
ture. The restored teeth were subjected to thermal cycling (Automatic
Thermaocyclic Dipping Machine, ATMD-T6PD, Malaysia) of 600
cycles in a 5˚-55
℃ water bath with a dwell time of 20s in each bath
and a 10s travelling time. This method was modified from Salwa K
and Khamis H 2011, efficacy of Composite Restorative Techniques
in Marginal Sealing of Extended Class V cavities. All tooth surfaces
were covered with two coats of nail varnish, with the exception of
1mm around the tooth restoration interface. The teeth were then
immersed in 2% methylene blue dye solution for 24 hours at room
temperature. Then the teeth were rinsed thoroughly with tap water
and sectioned vertically with hard tissue cutter (EXAKT, Germany)
in the middle of the restored cavity into mesial and distal parts to
yield 2 specimens per tooth (32 specimens per group).
The sectioned teeth were observed and digitally photograph using
digital camera (JVC Ky-F55B, Japan) attached to a macrostand (Mini
repro- Industria fototecnica FIRENZE) at 30X magnification.
Microleakage depth was measured in micrometer (µm) and both the
coronal and cervical measurements were recorded. The dye penetra-
tions were examined by two independent evaluators. The min values
of the evaluators' measurements were recorded and their percentages
of dye penetration were analyzed with One Way ANOVA followed
by Post-hoc (Tukeys) using SPSS 18.0.
RESULTS
The data was analyzed by using Statistical Package of the Social
Sciences (SPSS) version 18.0 (SPSS Inc., Chicago IL). The number
of teeth and the percentage of dye penetration for each group were
presented in Table 1. The summary of statistical analysis of the data
obtained for the percentage of dye penetration is presented in Table 2
and table 3 respectively. None of the restorative materials tested in
this study completely eliminate microleakage. The mean percentage
of dye penetration with Filtek Z350 restoration is 87.81%, ceramage
A3B is 77.31% and porcelain is 76.25%. One-way Anova indicated
that there was significant difference (p = 0.032) in the comparison of
the percentage of microleakage between the 3 groups. Post Hoc test-
Tukey showed that the significant difference (p = 0.045) is from
comparing the percentage of microleakage between direct composite
group and porcelain group. However, there is no significant differ-
ence (p = 0.077) in percentage of microleakage between direct and
indirect composite (Fig. 2 and 3) and no significant different (p =
0.973) in percentage of microleakage between indirect composite and
porcelain group (Fig. 4).
DISCUSSION
Since the beginning of dentistry, much research had been done to
overcome the problem of microleakage in dental restoration especial-
ly in Class V cavity but until today, there are no dental restorative
Microleakage of Composite and Porcelain
Figure 2. Dye penetration of composite
resin restoration under Leica
Imaging System 30X
Figure 3. Dye penetration of indirect com-
posite resin restoration under
Leica Imaging System 30X
Figure 4. Dye penetration of porcelain
restoration under Leica imaging
System 30X
materials or techniques which can truly eliminate microleakage.
Class V preparations were used because they have a high C-factor
design- preparations with high ratio of bonded "flow-inactive" to free
"flow-active" surfaces (Wahab et. al., 2003). The direct composite,
Filtek Z350 Universal Restorative (3M ESPE, USA) was used in my
study as it is frequently used in USM dental clinic. Filtek Z350, a
universal restorative nanocomposite is suitable in restoring Class V
cavity because it displays the after polish retention of a micro-fill
while maintaining the strength and wear properties of a modern
hybrid (Z350 product profile, 2005).
The choice of extreme temperature of 5
℃ and 55℃ is based on
the lowest and the highest temperature that an average person can
adapt orally and such a regiment has been used in several studies (De
Paula et. al., 2008). Wahab et. al. 2003 showed that 70.8% and
79.8% of the class V preparations exhibited microleakage at the
enamel and dentin margins of the preparations respectively, after 500
cycles of thermal cycle. Chan KC and Khera SC, 1978 concluded in
their research that hand instrument-finished cavity preparation allow
significantly less marginal leakage than those which are only com-
pleted with rotary instrument. Besides that, their research showed
cavity preparations are more prone to marginal leakage at sharply
defined cavosurface acute angles compared to smooth or straight sur-
faces of cavity. Therefore, rough cavity walls and acute cavosurface
angles may be potential confounding factors in my research especial-
ly pertaining to the indirect composite group. Another factor would
be the difficulty to properly condense a restorative material in
sharply defined acute angle areas which may leave undetected voids
(Howlader et. al. 2013) during visual or explorer examination.
Hence, these regions were vulnerable to microleakage.
In this study, there is still dye penetration at the margins of direct
and indirect composite resin restoration even after using incremental
techniques. Kheir S. and Hassan K., 2010 concluded, none of the
composite resin restorative techniques used for restoring extended
class V cavities produced gap free margin and this further supports
our research. However, incrementally placement before curing of the
composite resin materials is essential to minimize the effect of com-
posite shrinkage (Bayne et. al., 1994). The elimination of polymer-
ization shrinkage of composite resins presents a great challenge to the
dental profession. Composite resin which has undergone free radical
polymerization of the methacrylate groups will subsequently be
observed to have a reduction in volume, causing polymerization
shrinkage that may vary from 1% to 5% of the original volume
(Robbins and Fasbinder, 2001). Results also showed greater marginal
leakage of composite resin when comparing direct composite with
porcelain restoration in class V cavity while no significant differ-
ences were noticed between direct and indirect composite. Wahab et.
al. 2003 reported that the types of composite used had no significant
difference in microleakage; 5 out of the 6 types composite material
used showed a similar performance in class V preparation although
the composition and the filler type varied considerably.
Additional problems with these restorations are presented by the
difference in coefficients of thermal expansion (CTE) between tooth
structures and dental materials. CTE is a measurement of the degree of
expansion when heated and contraction when cooled of a given materi-
al. A difference in the CTE between restorative material and tooth could
be the cause of marginal gap leakage. The lower the value of CTE, the
less changes in size of the material when it is subjected to temperature
changes (Bullard et. al., 1988). The CTE of the crown of human teeth is
known to be 11.90 (SD 4.42) x 10
-6
/℃, (Xu et. al. 1989), the IPS e.max
Press has a CTE of 10.15 ± 0.4 x 10
-6
/K.(Tysowsky GW, 2009) and for
composite materials, the CTE ranges from 22.5 to 45 x 10
-6
/℃.
(Verslius et. al., 1996) Hence, in oral cavity where thermal changes
occur or with regards to this study, a thermocycle was used instead to
simulate the above, restorative materials such as porcelain with CTE
value approximately similar as CTE of human teeth will result in lesser
marginal gap formation between the porcelain-tooth interfaced.
In this research, we used IPS e.max Press, which is a lithium dis-
ilicate glass ceramic ingot. IPS e.max Press has the advantage of
being thermally shock-resistant due to its low CTE value. Besides
that, this material involves using Empress pressing equipment in pro-
ducing the inlays. Empress pressing equipment is known for produc-
ing well adapted inlay without any discrepancy in size and shape.
(Tysowsky GW, 2009). In addition, Rely
TM
U100 which acts as self-
adhesive universal resin cement is chosen for its high stability in
combination with good flowability under pressure. (RelyX U100
phamplet) The usage of silane coupling agent also improves the
bonding of RelyX U100 adhesive resin cement to porcelain. Silane is
a dual function monomer consisting of a silanol group that reacts
with the porcelain surface, and a methacrylate group which co-poly-
merizes with the resin matrix of the composite. Silane coupling
agents are known to increase physical, mechanical and chemical
bonding of composite to porcelain, and yield a greater resistance to
water attack at the bonding interface. All of these factors should con-
tribute to a better marginal fit of porcelain restorations over direct
and indirect composite resin restorations. However, in another jour-
nal, it states that for any cemented restorations, the weak link is at the
restoration-cement-tooth interface. In porcelain inlay and indirect
composite restoration, the resin luting agent is the weak link. When
used as luting agent, the bulk of composite resin is reduced.
However, there is still polymerization volumetric shrinkage in the
amount of 2.6% to 5.7% which may create a marginal opening or loss
of the marginal seal (John et. al. 1992).
It is found that porcelain is generally better than direct and indirect
composite resin in-terms of microleakage. Therefore, our results sug-
gest, porcelain cervical inlay as a new and better alternative in restor-
ing Class V cavity. However, it is difficult to predict the effectiveness
of porcelain cervical inlay as Class V restoration because the environ-
ment in the oral cavity is different from laboratory environment. In
addition, a number of studies have demonstrated dissolution of the
resin matrix of composite resin in oral fluid (John et. al., 1992).
ACKNOWLEDGEMENT
The author would like to acknowledge Prof. Dato' Dr. Abdul
Aziz Abdul Razak and the technician of Biomaterial Laboratory of
Faculty of Dentistry, University of Malaya, Encik Shaiful of
Prosthetic Laboratory and the staff of Craniofacial Laboratory,
School of Dental Sciences of Science University of Malaysia for their
endless support. This study was supported by USM Incentive Grant.
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