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Int Chin J Dent 2008; 8: 53-61.

Influence of aging on direct resin composite repair bondAtia Anjum, BDS,a Khairul Matin, BDS, PhD,a,b Ryoichiro Uchida, DDS,a,b and Junji
Tagami, DDS, PhD,a,b,cabCariology and Operative Dentistry, Department of Restorative Sciences, Support Program forc
Improving Graduate School Education, and Global Center of Excellence (GCOE) Program;International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and
Dental University, Tokyo, Japan

Purpose: The objective of this study was to evaluate the effect of aging on repair bond strength of direct resin
composites.
Materials and Methods: Total of 45 (D: 9 mm and L: 4 mm) composite specimens were prepared (ClearfilAP-X). Forty-two specimens were kept for storage in Milli-Q water and in human saliva at 37ºC for 2, 4, and 12
weeks. Rest three non-aged specimens (L: 8 mm and D: 9 mm) were used as control. Each aged specimen was
roughened by a an abrasive point, washed with water jet and air dried. Then, silane was applied followed by theapplication of Clearfil SE bond. After surface treatment, fresh composite of same resin: SR (Clearfil AP-X) anddifferent resin: DR (Estelite Σ) was added and light cured in each group. After 24 hours of storage in water at
37°C, all the repaired and non repaired control specimens were cut into 1 mm sticks with a cross-sectional areaof 0.7 mm2 at the bonding interface and microtesile bond strength test was performed. The fracture modes andsurface alterations were inspected by using a scanning electron microscope. Data were analyzed by two-way
and one-way ANOVA.
Results: Post-hoc comparison showed significantly reduced bond strength between 2 weeks saliva SR (43.97)
and 12 weeks Milli-Q water DR (35.11) groups. When compared to control, Dunnett T3 test revealed
significantly decreased bond strength in all groups of 12 weeks.
Conclusion: The composite repair bond strengths were influenced by the different types of storage solutions andresin composition. (Int Chin J Dent 2008; 8: 53-61.)
Key Words: aging, composite resin, human saliva, repair bond strength.

Introduction
Composite resins have been extensively used as direct restorations for their high-quality esthetic properties.
To improve their properties, the incessant modifications in resin composites are being done continuously.
Specifically, longevity or aging resistance of direct resin composites is a very important property that needs lot
more effort to improve the quality of the tooth color restorations clinically. However, repair of the aged resin
restorations are considered occasionally.
The degradation processes of dental composites are complex and possibly due either to mechanicaldegradation mechanisms1 such as wear, abrasion, and fatigue, or chemical degradation mechanisms such as
enzymatic, hydrolytic, and acidic action, or temperature-related breakdown.2 These changes may result in
discoloration, micro leakage, ditching at the margins, delamination, or simply fracture, which may affect thebonding properties when repair is considered as a treatment option. According to the principle of minimal
intervention dentistry, repair rather than replacement of the defective restorations3 is the preferable treatment
choice nowadays. Careful case selection and correct usage of surface treatment agents, followed by the use of aquality bonding system and restorative materials, can result in a repair that exhibits excellent retention andnatural color blending.4
Several studies have evaluated the resin-resin union between aged resin surfaces and new resin increments,
simulating a repair condition. Different surface treatments have been proposed, with variable results. Thesemethods included chemo-mechanical preparation of the resin surface, such as abrasion, etching withhydrofluoric or phosphoric acid and use of intermediate bonding agents to enhance repair bond strength.5 Also,
it has been indicated that roughening of surfaces promotes mechanical interlocking, the bonding agent improves

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surface wetting and chemical bonding with the new composite.2 Abrasion of the aged resin surface withdiamond burs,6-8 carborundum,7 low-pressure silicate ceramic deposition7 or sandblasting6-8 provides satisfactorybond strength between the resin increments.9 Additionally, the application of silane with or without previous
mechanical preparation has been advised in composite resin repair. In a study by Brosh et al.,7 silanization andunfilled resin slightly but not significantly improved the repair strength compared to unfilled resin alone. In
another study, the use of silane combined with diamond bur roughening significantly improved the bond strength
between repaired surfaces.7
In the laboratory, aging is simulated by storage of specimens in aqueous solutions for different lengths of timeand maintaining the temperature usually at 37ºC. In previous in vitro studies, commonly used storage media
were water, deionized water, saline solution, ethanol or artificial saliva for different time periods.
Thermocycling and water storage of bonded specimens are well-accepted methods to simulate aging and to
stress interfacial bonds.10
In recent years, although increasing number of researchers have adopted the microtensile technique as a moreaccurate method for the assessment of the interfacial strength11 but only a few studies have evaluated thecomposite-to-composite microtensile bond strength.12 Eiriksson, et al.,13 recently reported the influence ofsalivary enzymes on wear.
To get optimum bond strength, the best choice is to use the same composite resin or at least select a materialof the same family or manufacturer with the original composite resin. Repair composite resins from different
manufacturer sometimes may have to be chosen because of certain unavoidable situations, e.g.; unavailability.
The union between these resin composites is a very important factor for the success of the restoration which
concerns function and aesthetics as well.12 Therefore, the objective of this study was to evaluate the effect ofdifferent storage conditions on repair bond strength of composites.

Materials and Methods
Sample preparation
The materials used in this study are listed in Table 1. Total of 45 cylindrical composite specimens, 4 mm inheight and 9 mm in diameter were prepared by layering 2 mm thick increments of Clearfil AP-X (Kuraray
Medical Inc., Tokyo, Japan, shade A2) in transparent plastic mold according to manufacturer’s instruction. Each
increment was carefully condensed into the mold with a clean plastic spatula and light-polymerized for 20 s (600mW/cm2 power output halogen light source, Optilux 500, Demetron, Danbury, CT, USA). The last increment
was covered with a plastic strip and a glass slide to achieve a flat surface of the specimen after light curing.
Forty two specimens were kept for storage. Rest three specimens (L: 8 mm and D: 9 mm) were used as control.
Human saliva collection
Stimulated saliva (by chewing sugar free gum) was collected 2 hours after breakfast in a sterile centrifuge tube
(TPP, Gerard Biotech, Oxford, OH, USA) followed by tooth brushing and embedded in ice from pre-informed
healthy lab volunteer.

All the collected saliva were then centrifuged (Kubota, High Speed Refrigerated

Centrifuge, Model 6500, Tokyo, Japan) at a speed of 15,000 rpm (24,400xg) for 10 minutes at 4ºC. Supernatantsaliva from the centrifuge tube was then transferred into the upper chamber of a filter-top centrifuge tube
(Corning Incorporated, CLS 430320, pore size 0.22 µm, Corning, NY, USA) and filtered by a Teflon dry
vacuum pump (DTC-21, Diaphragm Type Teflon Vacuum Pumps, Ulvac Kiko, Inc., Chigasaki, Japan). The 50

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Int Chin J Dent 2008; 8: 53-61.

mL reservoir was capped inside of a bio clean-bench (MCV-B91F, Sanyo, Osaka, Japan) discarding the filter.
The reservoir containing saliva was then stored in a refrigerator at 4ºC. Every time the saliva was collected fromthe same person.
Table 1. Composition, manufacturers, and lot numbers of the materials used.
Material

Composition

Manufacturer

Lot number

Clearfil SE-Bond

Primer: MDP, HEMA, Dimethacrylate monomer, Water,
Catalyst
Bond: MDP, HEMA, Dimethacrylate monomer, Microfiller,
Catalyst
Bisphenol A polyethoxy dimethacrylate,
3-methacryloxypropyl trimethoxysilane

Kuraray Medical
Inc.,
Tokyo, Japan

00721A
01034A

Kuraray Medical
Inc.

00209A

Clearfil AP-X

Barium glass, Silica colloidal silica, Silicon
dioxide (71 vol%, 0.1-1 µm),
Bis-GMA, TEGDMA, Photoinitiator

Kuraray Medical
Inc.

Palfique Estelite Σ

Silica zirconia, Prepolymerized organic filler(71 vol%, 0.2 µm), Bis-GMA, TEGDMA, Photoinitiator

Tokuyama Dental
Corp., Tokyo, Japan

A2:0957AA
A3.5:
0629AA
C2: W805

Clearfil Porcelain Bond
Activator

Aging the resin composite specimen in vitro
Seven specimens of composite resin were stored in each storage media (de-ionized/ Milli-Q water and humansaliva) in an incubator (Sanyo, MIR-162, Osaka, Japan) at 37ºC for 2, 4, and 12 weeks. The pH of all of theliquids was measured with a pH meter (Horiba, Kyoto, Japan) before the storage of the specimens [human saliva(pH 8.05), Milli-Q water (pH 6.5)]. Each specimen was stored in separate conical tube (Falcon, 35-2096, BlueMax Jr. 15 mL Polypropylene Conical Tube, Becton Dickinson, Franklin Lakes, NJ, USA). After 2, 4, and 12
weeks, six aged specimens from each media were removed and surface treatments were done.

Control

specimens were not aged.
Repairing the resin composite specimens
One side of the each specimen was roughened by an abrasive point (Shofu Inc., Kyoto, Japan) mounted on
low-speed hand piece for 10 s, washed with water jet and dried with air for 20 s. After that, silane (mixture ofequal amount of Clearfil SE bond primer and Clearfil Porcelain Bond Activator) was applied for 5 s followed byair dried and application of Clearfil SE bond. Bonding agent was air dried and light cured for 10 s. Aftersurface treatment, each group of composites was again divided into two groups according to the composite resin
used for repair (n=3). All of the samples were reassembled into the mold and the increments of fresh composite
of same resin-SR (Clearfil AP-X, shade A3.5) and different resin-DR (Estelite Σ, shade C2) were added and light
cured as mentioned above.
Measurement of micro-tensile bond strength (µTBS)
After 24 hours of storage in water at 37°C, all the repaired and the control specimens were cut into slabs of 1mm thickness using a low speed diamond saw (Isomet, Buehler, Lake Bluff, IL, USA) under water cooling.
Each slab was again serially sectioned to multiple sticks at a depth of 1 mm. The sticks were trimmed to anhourglass shape at the bonding interface with a cross-sectional area of 0.7±1 mm2 using a superfine diamondpoint (SF114, Shofu Inc.) under water cooling. The ends of the sticks were glued to a testing device in atable-top testing machine (EZ Test, Shimadzu Co., Kyoto, Japan) using cyanoacrylate glue (Zapit, Dental
Venture of America, Anaheim, CA, USA), and subjected to a tensile force at a crosshead speed of 1 mm/minute.

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The cross-sectional area of each stick was measured using a digital caliper (Mitutoyo CD15, Mitutoyo Co.,
Kawasaki, Japan). The µTBS were calculated by dividing the fracture load by the surface area, measured to thenearest 0.01 mm with the digital calipers.
Fracture mode analysis
After the micro-tensile bond test, surfaces of the fractured beams were mounted on brass tablets and gold
sputter-coated. The fracture modes were observed using a scanning electron microscope (JSM-5310, JEOL,Tokyo, Japan). Mode of failure was classified as cohesive failure in resin composite (substrate or the repairing
composite), adhesive (at the interface) or mixed failure (combination of adhesive and resin cohesive failure).
Topographical analysis of the aged sample surfaces
To compare and observe the surface changes, remaining aged specimen from each storage media and storage
time were dried and kept in ambient condition in a desiccator and were gold sputter-coated and observed using ascanning electron microscope (JSM-5310) to evaluate the topographical changes.
Statistical analysis
Data were analyzed by separate two-way ANOVAs with bond strength as dependent variable, and storage
solution and resin type as factors. Tukey’s test was then performed for post-hoc comparison in between thegroups. One-way ANOVA and Dunnett T3 test was also performed to compare the experimental groups with
control. Data were analyzed using the Statistical Package for the Medical Science (SPSS Ver.15 for Windows,
Chicago, IL, USA) for statistical procedures.

Results
Mean micro-tensile bond strength values with standard deviations are summarized in Table 2. The two-way
ANOVA showed that composite repair bond strengths were influenced by the difference of the storage solutions
and also by the composition of the resin. Post-hoc comparison showed significantly reduced bond strength
between 2 weeks saliva SR (43.97±11.2 MPa) and 12 weeks Milli-Q water DR (35.11±3.17 MPa) groups. But
no significant differences were found between the SR of saliva and Milli-Q water in between all groups until 12
weeks. SR of saliva always showed higher bond strengths than the SR of Milli-Q water and the DR of saliva on
the other hand also showed higher bond strengths than the DR of Milli-Q water groups. When compared tocontrol, Dunnett T3 test revealed significantly decreased bond strength in all groups of 12 weeks, DR(40.85±8.13 MPa) of 2 weeks Milli-Q water, DR (37.42±12.17 MPa) of 4 weeks Milli-Q water and DR(38.95±10.85 MPa) of 4 weeks saliva.
Table 2. Means and standard deviations of the micro-tensile bond strengths (µTBSs) in MPa.
Storage media

Repaired resin

2 weeks

4 weeks

12 weeks

Same resin-SR

43.97±11.21 A

42.45±12.88

41.65±6.24 ab*

Different resin-DR

41.04±9.57

38.95±10.85 *36.96±8.16 a*Same resin-SR

42.21±12.93

39.56±16.58

37.46±4.86 *Different resin-DR

40.85±8.13 *37.42±12.17 *35.11±3.17 Ab*

Human saliva

Milli-Q water

Different letters indicate statistically significant differences (p<0.05). Asterisks (*) indicate the groups in which the repair µTBS
was significantly lower than the control cohesive strength (non aged, 47.67±6.32 MPa), (n=25).

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Failure mode distribution in the tested groups is reported in Fig. 1. Highest adhesive failure was recorded in
12 weeks Milli-Q water DR group. In SR groups of both saliva and Milli-Q water, cohesive failures were
between 36% and 42% and the mixed failures were ranged from 24-44%. Mixed failures were mostly observedin the saliva DR group (40%) at 2 weeks and 12 weeks showed 36%. Milli-Q SR groups at 4 weeks showed
mainly mixed failures (36%). Fractured specimen stored in human saliva for 12 weeks, restored with same resin(SR) shows mixed failure where most of the area were resin composites (aged/repair) with some small area ofpartially exposed silane/adhesive bonding agent (Fig. 2a). DR group of specimen stored for 12 weeks in humansaliva also shows mixed failure where silane/adhesive and resin were observed separately (Fig. 2b). Fractured
specimen stored in Milli-Q water for 12 weeks (SR) shows mixed failure, small area of partially exposedsilane/adhesive bonding agent were observed within the resin composite (Fig. 3a). DR group of 12 weeks
MilliQ-water specimen shows complete adhesive failure (Fig. 3b).

Fig. 1. Failure mode (%) distribution in the experimental groups.

Fig. 2. Representative SEM images (1000×) of fractured specimens stored in human saliva for 12 weeks.
(a) Restored with same resin (SR-APX) shows mixed failure, small area of partially exposed silane/adhesive(asterisk) bonding agent. (b) Restored with different resin (DR-Estelite ∑) shows mixed failure, silane/adhesiveand resin are showing separately.

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On SEM inspection surface deformity was observed on all composite resin specimens stored either in humansaliva or in Milli-Q water (data not shown). However, in comparison the specimen aged in saliva revealedsmoother surfaces than the Milli-Q water specimens (Fig. 4). Some debris and nano sized depositions weredetected on the surface of 12 weeks saliva specimen (Fig. 4a). After 12 weeks, leaching out of fillers was morein Milli-Q water specimens (Fig. 4b) and structural deformity was less on the surface of the saliva specimen.

Fig. 3. Representative SEM images (1000×) of fractured specimens stored in Milli-Q water for 12 weeks.
(a) Restored with same resin (SR-AP-X) shows mixed failure, small area of partially exposed silane/adhesive(asterisk) bonding agent. (b) Restored with different resin (DR-Estelite ∑) shows adhesive failure.

Fig. 4. Representative SEM image (1000×) of specimen stored for 12 weeks in human saliva (a) and MilliQ-water(b). Arrowheads indicate debris attached to the specimen surfaces. Black-asterisk indicates a large cavity-likedeformity on the resin surface due to leaching of fillers during the storage in Milli-Q water for 12 weeks.

Discussion
The hydrolytic degradation of composite resin materials happens mainly because of accumulation of water
between the filler-matrix interface that promotes the displacement of inorganic particles14 or due to the slow
development of superficial flaws related to preexistent corrosive processes.15 It is believed that the water
sorption causes resin softening by swelling of the polymer network and decreasing of the frictional forces
between the polymeric chains.16 Söderholm et al.17 reported that filler leaching of composites was much higher
in artificial saliva than in distilled water. The dissolution or elution of leachable components of composite resins,
mainly inorganic ions or filler particles, may present, at short or long period, a deleterious effect in the polymeric
network of the material, modifying its structure physically and chemically.
In the present study, stimulated whole saliva was used to observe the differences from deionized water as58

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water is frequently used as an in vitro aging medium. Ben-Aryeh et al.18 reported that no significant differenceswere found in salivary concentrations of sodium, potassium, calcium, magnesium and total protein between
whole and parotid, resting and stimulated saliva. Saliva is mostly water 99.4% with 0.6% solids. The solid iscomposed of macromolecules like proteins, glycoprotein sugars and amylase, inorganic particles like calcium,
sodium and chloride and organic particles like urea, amino acids, fatty acids and free glucose.18 Both the storage
media used in this study were aqueous media. And these two aqueous media caused significant reduction ofbond strength of barium glass filler containing Clearfil AP-X after 12 weeks. Usually the changes start from thecomposite surfaces. The mechanism of hydrolytic degradation is enhanced if the filler particles have metallicions in their composition.17,19 An explanation of this effect is would be; some ions in the filler particles, such as
zinc and barium, are electropositive and tend to react with water. With the loss of these elements into water, thecharge balance inside the silica network is changed and reestablished with the penetration of hydrogen ions of
the water in the spaces occupied by the zinc and barium. As a result of the increased concentration of hydroxylions, the siloxane (Si-O-Si) bonds of the silica network start to break, and there is formation of an autocatalytic
cycle of surface degradation.17,20,21 This mechanism would explain the continuity of the superficial softening
with aging time. Both the composite resins used for the present study have about similar compositions and sameamount of fillers by volume. There are some dissimilarity among the size, shape and the type of fillers between
these two composite resins. Due to these discrepancies and also for the different performances of the complex
polymerization procedure, probably the bond strengths were lower when they repaired together.

This

explanation also supports the highest adhesive failure in 12 weeks Milli-Q water DR group. Repairing with thesame resin composite had showed higher bond strengths in case of both storage media. But it was higher when
composites stored in saliva.

Okada et al.22 suggested that, when osmotic pressure will be taken into

consideration, acrylic polymers in the hydrogel matrix immersed in distilled water should absorb more water
than those in saliva. They also showed that composite resin did not react with Ca2+ and PO43- ions from saliva.
Specimens stored in Milli-Q water in the present study showed lower bond strengths very probably due to muchwater uptake which caused higher hydrolytic degradation.
Both the storage media showed significant reduction of bond strength and that of DR stored in Milli-Q water
after 12 weeks reduced down to 20.15% compared to SR stored in Saliva for 2 weeks. After 12 weeks, DRgroup of Milli-Q water also showed significantly reduced (15.7%) bond strength from SR of saliva of same time.
Saliva contamination significantly reduces the adhesive strength between resin increments9 and an effective
decontamination of the surface must be performed to improve the adhesive strength between resin-resin
increments. For this reason, a convenient and well accepted method was followed in the present study as several
studies showed that abrasion or mechanical preparation of the contaminated surface followed by the applicationof silane and adhesive resulted higher resin-resin bond strength. Hisamatsu et al.23 found the similar values ofcohesive strength when silanes were employed in the repair procedure of composites. Mixing of adhesive resins
with the ethanol-based PBA silane coupler results in a complex blend containing nonvolatile hydrophilic(HEMA and 10-MDP) and hydrophobic (Bis-GMA) resin monomers dissolved in volatile solvents, such as ethyl
alcohol, water alone, or in combination.24 Coating the previously air-dried silane/primer layer with a morehydrophobic bonding resin applied as a separate step may have accounted for superior adhesive potential of
PBA/Clearfil SE Bond repair system.25
SEM photomicrographs apparently showed that all the specimen surfaces aged in saliva and Milli-Q water59

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Int Chin J Dent 2008; 8: 53-61.

received some hydrolytic degradation. But it was prominent at 12 weeks Milli-Q water specimen. Specimens
stored in saliva revealed less degradation all through the storage period. After 12 weeks, filler leached out fromresin matrix were observed in Milli-Q water specimen. Some debris and nano sized depositions were detectedon the surface of 12 weeks saliva specimen; these might be salivary proteins and inorganic particles that were
deposited during long storage period.
In vitro studies do not reflect what exactly occurs in an oral cavity and offer inaccurate information in regards
to the interaction between restorative materials and oral phenomena. When inserted in the oral environment,
restorative materials are exposed to saliva, pH changes and other factors such as food and liquid. In the present
study, repair bond strength of resin composites were affected more when aged in Milli-Q water and the repair
resin was different compared to aged in human saliva. To get an optimum reflection of the oral environment, theuse of human saliva as storage medium is not so much inconvenient though the solid contents of the saliva varies
from individuals. With respect to the hydrolytic degradation process, as different types of restorative composite
resins and polymerization methods exhibit different performances, further studies will need to be carried out
with different resin composites and human saliva for longer period of time.
Acknowledgments
This study was supported by the Global Center of Excellence (G-COE) Program for International Research Center for Molecular Sciencein tooth and Bone Diseases at TMDU, Tokyo, Japan and Support Program for Improving Graduate School Education at TMDU, Japan.

References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.

Johannes B, Özcan M. Effect of physicochemical aging conditions on the composite-composite repair bond strength. J
Adhes Dent 2007; 4: 399-406.
Ortengren U, Welleendorf H, Karlsson S, Ruyter IE. Water sorption and solubility of dental composites and identification ofmonomers released in an aqueous environment. J Oral Rehabil 2001; 28: 1106-15.
Martin JT, Kenneth JA, Jo EF, Graham JM. Minimal intervention dentistry – a review. FDI Commission Project 1-97. Int
Dent J 2000; 50: 1-12.
Denehy G, Bouschlicher M, Vargas M. Intraoral repair of cosmetic restorations. Dent Clin North Am 1998; 4: 719-37.
Cristina LM, Santiago GL, José MNRM. The effects of various surface treatments and bonding agents on the repaired
strength of heat-treated composites. J Prosthet Dent 2001; 86: 481-8.
Kupiec K, Barkmeier W. Laboratory evaluation of surface treatments for composite repair. Oper Dent 1996; 21: 59-62.
Brosh T, Pilo R, Bichacho N, Blutstein R. Effect of combinations of surface treatments and bonding agents on the bondstrength of the repaired composite. J Prosthet Dent 1997; 77: 122-6.
Bonstein T, Garlapo D, Donarummo J Jr, Bush PJ. Evaluation of varied repair protocols applied to aged composite resin. J
Adhes Dent. 2005; 7: 41-9.
Furuse AY, Cunha LF, Benetti AR, Mondelli J. Bond strength of resin-resin interfaces contaminated with saliva andsubmitted to different surface treatments. J Appl Oral Sci 2007; 15: 501-5.
Sideridou T, Achilias DS, Kyrikou E. Thermal expansion characteristics of light-cured dental resins and resin composites.
Biomaterials 2004; 25: 3087-97.
Pashley DH, Carvalho RM, Sano H, et al. The microtensile bond strength: A review. J Adhes Dent 1999; 1: 299-309.
Pappacchini F, Dall'Oca S, Chieffi N, et al. Composite-to-composite microtensile bond strength in the repair of a microfilled
hybrid resin: Effect of surface treatment and oxygen inhibition. J Adhes Dent 2007; 9: 25-31.
Eiriksson SO, Pereira PN, Swift EJ Jr, Heymann HO, Sigurdsson A. Effects of saliva contamination on resin-resin bondstrength. Dent Mater 2004; 20: 37-44.
Bowen RL, Reed LE. Semiporous reinforcing fillers for composite resins: I Preparation of provisional glass formulations. J
Dent Res 1976; 55: 738-47.
Michalske TA, Freiman SW. A molecular mechanism for stress corrosion in vitreous silica. J Amer Ceram Soc 1983; 66:
284-8.
Jaffer F, Finer Y, Santerre JP. Interactions between resin monomers and commercial composite resins with human saliva
derived esterases. Biomaterials 2002; 23: 1707-19.
Söderholm KJM, Mukherjee R, Longmate J. Filler leachability of composites stored in distilled water or artificial saliva. J
Dent Res 1996; 9: 1692-9.
Ben-Aryeh H, Shalev A, Szargel R, Laor A, Laufer D, Gutman D. The salivary flow rate and composition of whole andparotid resting and stimulated saliva in young and old healthy subjects. Biochem Med Metab Biol 1986; 36: 26-5.
Söderholm KJM. Leaking of fillers in dental composites. J Dent Res 1983; 62: 126-30.
Charles RJ. Static fatigue of glass I. J Appl Physics 1958; 29: 1549-53.
Lovell MR, Dalgliesh M, Richardson RM, Barnes AC, Enderby JE, Evans B. Depth of water incorporation into float
glasssurfaces studied by neutron reflection. Phys Chem Chem Phys 1999; 1: 2379-81.
Okada K, Tosaki S, Hirota K, Hume WR. Surface hardness change of restorative filling materials stored in saliva. Dent
Mater 2001; 17: 34-9.
Hisamatsu N, Atsuta M, Matsumura H. Effect of silane primers and unfilled resin bonding agents on repair bond strength ofa prosthodontic microfilled composite. J Oral Rehabil 2002; 29; 644-8.

60

Anjum et al.
24.
25.

Int Chin J Dent 2008; 8: 53-61.

Papacchini F, Monticelli F, Hasa I, et al. Effect of air-drying temperature on the effectiveness of silane primers and coupling
blends in the repair of a microhybrid resin composite. J Adhes Dent 2007; 9; 391-7.
Monticelli F, Osorio R, Toledano M, Goracci C, Tay FR, Ferrari M. Improving the quality of the quartz fiber postcore bondusing sodium ethoxide etching and combined silane/adhesive coupling. J Endod 2006; 32: 447-51.

Correspondence to:
Dr. Atia Anjum
Cariology and Operative Dentistry, Department of Restorative Sciences, Tokyo Medical and Dental University
1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
Fax: +81-3-5803-0195 E-mail: dranjum2004@yahoo.com
Received November 6, 2008. Accepted December 2, 2008.
Copyright ©2008 by the International Chinese Journal of Dentistry.

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