• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.359-367
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• 2019

For this study, specimens were prepared using five types of composite resin and resin-reinforced glass ionomer Fuji II LC, and 29 days precipitation was done in four kinds of solution, which were soy sauce, gochujang, wine, and distilled water. Ten specimens for each coloring sample were divided into two groups, one those surfaces was polyester film and the other with 1200-grit abrasive paper, and 20 specimens per materials. Color change (${\Delta}{\ast}ab$) in the colored specimens is measured in 2days, 7days, 14days and 29days using spectrophotometer (CM-2600d, Konica, Minolta, Ramsey, NJ). All values were considered significant when P<0.05. 1. Each material is discolored over time under the influence of different storage solutions. 2. In soy source, among the specimens polished with polyester film, color change was observed in resin-modified glass ionomer Fuji II LC, prodigy and compomer F-2000 on day 2. Meanwhile, Fuji II LC showed noticeable color change in specimens prepared with 1200-grit sandpaper on day 2, which was followed by flowable resin on day 7. 3. On day 2, there was a color change with the specimens of flowable resin, resin-modified glass ionomer Fuji II LC and Prodigy among the hybrid specimen in the groups of polyester film in gochujang.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.89-96
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• 2018

Purpose: The aim of this study was to evaluate the effect of delayed time, surface treatment, and repair materials on repair of bis-acryl composite resin through comparison of shear bond strength and to evaluate the utility of bis-acryl composite resin repair using polymethyl methacrylate resin. Materials and Methods: A total of 90 bis-acryl composite resin specimens were fabricated and classified into 9 test groups, each of 10 pieces according to delayed time, surface treatment and repair material. The shear bond strength of each specimen was measured using a universal testing machine immediately after fabrication and analyzed using a statistical analysis program (IBM SPSS statistics 20). After the shear bond strength measurement, the fracture surface of the specimen was observed. Results: The highest shear bond strength ($17.54{\pm}3.14MPa$) was observed in the experimental group bonded immediately with a light-curing flowable composite resin using a bonding agent. Conclusion: When repairing bis-acryl composite resin, it is necessary to consider whether to remake according to the delayed time. For effective repair, it is desirable to consider appropriate materials and surface treatment methods according to the site or purpose of use.

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.542-549
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• 2007

The purpose of this study was to evaluate the difference in the surface roughness after polishing and to evaluate the difference in color stability after immersion in a dye solution among four types of composite resin materials. Four light-polymerized composite resins(Shade A2) with different sized filler content(a nanofilled, a hybrid, a microfilled, a flowble) were used. Average surface roughness (Ra) was measured with a surface roughness tester (Surftest Formtracer) before and after polishing with aluminum oxide abrasive discs(Super-Snap). Color of specimens before and after staining with 2% methylene blue solution were measured using spectrophotometer(CM-3700d) with SCI geometries. The results of Ra and ${\Delta}E$ were analyzed by one-way analysis of variance(ANOVA), a Scheffe multiple comparison test and Student t-test(p=0.05). After polishing, Ra values were decreased regardless of type of composite resins. In surface roughness after polishing and color stability after staining, nanofilled composite resin was not different with other composite resins except flowable resins.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.83-89
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• 2008

The purpose of this study was to evaluate the effect of the polymerization shrinkage and modulus of elasticity of composites on the cusp deflection of class V restoration in premolars. The sixteen extracted upper premolars were divided into 2 groups with similar size. The amounts of cuspal deflection were measured in Class V cavities restored with a flowable composite (Filtek flow) or a universal hybrid composite (Z-250). The bonded interfaces of the sectioned specimens were observed using a scanning electron microscopy (SEM). The polymerization shrinkage and modulus of elasticity of the composites were measured to find out the effect of physical properties of composite resins on the cuspal deflection. The results were as follows. 1. The amounts of cuspal deflection restored with Filtek flow or Z-250 were $2.18\;{\pm}\;0.92{\mu}m$ and $2.95\;{\pm}\;1.13\;{\mu}m$, respectively. Filtek flow showed less cuspal deflection but there was no statistically significant difference (p > 0.05). 2. The two specimens in each group showed gap at the inner portion of the cavity. 3. The polymerization shrinkages of Filtek flow and Z-250 were 4.41% and 2.23% respectively, and the flexural modulus of elasticity of cured Filtek flow (7.77 GPa) was much lower than that of Z-250 (17.43 GPa). 4. The cuspal deflection depends not only on the polymerization shrinkage but also on the modulus of elasticity of composites.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.320-326
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• 2020

The aim of this study was to compare compressive strength and microhardness of recently introduced alkasite restorative materials with glass ionomer cement and flowable composite resin. For each material, 20 samples were prepared respectively for compressive strength and Vickers microhardness test. The compressive strength was measured with universal testing machine at crosshead speed of 1 mm/min. And microhardness was measured using Vickers Micro hardness testing machine under 500 g load and 10 seconds dwelling time at 1 hour, 1 day, 7 days, 14 days, 21 days and 35 days. The compressive strength was highest in composite resin, followed by alkasite, and glass ionomer cement. In microhardness test, composite resin, which had no change throughout experimental periods, showed highest microhardness in 1 hour, 1 day, and 7 days measurement. The glass ionomer cement showed increase in microhardness for 7 days and no difference was found with composite resin after 14 days measurement. For alkasite, maximum microhardness was measured on 14 days, but showed gradual decrease.

• Journal of Korean society of Dental Hygiene
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• v.12 no.3
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• pp.533-541
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• 2012

Objectives : The purpose of this study was to evaluate the effects of tooth bleaching agent contained 35% hydrogen peroxide on the color, microhardness and surface roughness of tooth-colored restorative materials. Methods : Four types of tooth-colored restorative materials, including a composite resin(Filtek Z350 ; Z350), a flowable composite resin(Filtek P60 : P60), a compomer(Dyract$^{(R)}$ AP ; DY), and a glass-ionomer cement(KetacTM Molar Easymix ; KM) were used in the study. The specimens($8mm{\times}5mm$) were made by using a customized acrylic mold. Each material was divided into two groups equally(n=40) : experimental group(35% HP) and control group(distilled water). 35% HP group was treated 30 mim/5 days for 15 days. Each 30 minute treatment session consisted of two 15 minute cycles of gel application with 20 second light exposure. The authors measured the color, microhardness, and roughness of the specimens before and after bleaching. The data were analyzed with ANOVA and T-test. Results : 35% HP group showed an apparent color change(${\Delta}E^*$) than control group. In particular, DY and KM showed a noticeable color change and statistically significant differences(p<0.05). 35% HP group showed a reduction in microhardness. Z350 and P60 does not have a statistically significant difference(p>0.05), DY and KM showed a statistically significant difference(p<0.05). Percentage microhardness loss(PML) of control group was 0.6 to 5.5% in the group, 35% HP group was 6.6 to 34.6%. Roughness was increased in 35% HP group after bleaching. Especially DY and KM were significantly increased(p<0.05). Conclusions : Bleaching agents may affect the surface of existing restorations; therefore, they should not be used indiscriminately when tooth-colored restorations are present.

• Journal of dental hygiene science
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• v.21 no.3
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• pp.178-184
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• 2021

Background: As the importance of the esthetic function of teeth increases, the use of esthetic restoration materials and whitening treatment are increasing. The purpose of this study was to investigate the color change of esthetic restoration materials upon using staining and whitening toothpaste. Methods: Light curing (LC) packable composite resin, LC flowable resin, LC glass ionomer (GI), and self-curing GI specimens were colored in coffee or curry for three hours a day for seven days. After that, regular toothpaste, whitening toothpaste containing hydrogen peroxide, and whitening toothpaste containing activated charcoal were applied for three minutes three times a day for two weeks. Luminosity (L), chromaticity a (a), and chromaticity b (b) were measured using a spectrophotometer once a week. Results: In the coffee-colored group, the change in L^2*a^2*b² (E²) with time was significant (p=0.004), there was no difference for different toothpaste types (p=0.646), and there was significant difference (p<0.001) for different esthetic restorative materials. The change of E² in the curry-colored group was significant only for different esthetic restorative materials (p<0.001). In the coffee-colored group, the L, a, and b values of the light-curing GI showed greater change than other materials after staining and one week after whitening, turning dark, red, and yellow. In the curry-colored group, L did not differ for different materials and times, and a and b showed the greatest difference in light-curing GI after staining and one and two weeks after whitening. Conclusion: The use of whitening toothpaste for two weeks was not different from the use of general toothpaste in the removal of staining or whitening. Since light-curing GI is the most vulnerable to coloration, it is recommended that coloring by food chromogen should be explained in advance, before using light-curing GI for teeth restoration.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.1
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• pp.20-29
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• 2009

This study was performed to evaluate the effect of the shrinkage stress induced by polymerization process of several light curing filling materials according to filling methods. High power light curing unit which has a plasma arc lamp was used and filling materials used were Filtek $Z-250^{(R)}$ composite resin, $Dyract^{(R)}$ AP compomer and $Tetric^{(R)}$ Flow flowable composite resin. Cavities were prepared on the permanent molars with width 3 mm, height 3 mm and depth 1.5 mm and the filling materials were filled with 1 step, 2 step layering technique and 3 step oblique filling methods. The results can be summarized as follows; 1. Strain values showed rapid increase from the start of light curing followed by gradual decrease afterwards with time. 2. Although the shrinkage stress value of $Z-250^{(R)}$ were shown to be relatively higher than $Dyract^{(R)}$ AP and $Tetric^{(R)}$ Flow, no statistically significant could be found between tested materials(p>0.05). 3. There were no statistically significant difference between 3 filling methods when using $Dyract^{(R)}$ AP and $Z-250^{(R)}$(p>0.05). 4. There were no statistically significant difference between shrinkage stress values obtained from samples prepared by different filling methods and materials(p>0.05).

• Journal of dental hygiene science
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• v.15 no.4
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• pp.407-412
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• 2015

This study investigated flexural properties of indirect Gum-shade composite resins for esthetic improvement. The material utilized in this study was Crea.lign, Twiny flow and Twiny paste (TP). Ten specimens were fabricated with a dimension of $25{\times}2{\times}2mm$ according to the ISO 4049. After fabrications, specimens were stored in the distilled water for 24 hours at the temperature of $37^{\circ}C$. Three-point bending test was performed in universal testing machine (Instron 3344; Instron, USA) at a crosshead speed of 1 mm/min until the failure occurred. TP exhibited a higher flexural strength (FS) and flexural modulus (FM) compared to the flowable materials. There were significant differences among the three materials in FS and FM. However, there was no significant difference in work of fracture (WOF) in all tested materials (p>0.05). In Weibull analysis, TP showed the greatest Weibull modulus which means a higher reliability of the materials. Also, Gum-shade composite resins revealed a strong correlation in all flexural properties. There was a positive correlation in FS-FM ($r^2=0.99$) and a negative correlation between FS-WOF and FM-WOF ($r^2>0.97$). Therefore, this confirmed that flexural property was important for mechanical behavior evaluation and useful information. To addition, this improved among mechanical properties correlation of materials as important factor.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.27-32
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• 2013

Purpose: The aims of this study were to evaluate the effect of a resin coating on the shear bond strength of indirect composite restoration bonded to dentin with a self adhesive resin cement and to compare the shear bond strength with that of a conventional resin cement. Materials and methods: The occlusal enamels of thirty six extracted noncarious human molars were removed until the dentin flat surfaces of the teeth were exposed. Then, they were divided into 3 groups. The dentin surfaces of group 1 and 3 were left without any conditioning, while the dentin surfaces of group 2 were resin-coated with Clearfil SE bond and a flowable resin composite, Metafil Flo. After all specimens were temporized for 24 hours, indirect composite resin blocks fabricated by Tescera were bonded to dentins by Unicem for group 1 and 2, and by Panavia F for group 3. After 48 hours of water storage, shear bond strengths were measured. The data was analyzed with one-way analysis of variance and multiple comparison test (Tukey method). Results: The shear bond strengths of Unicem applied to resin coated dentin surfaces were significantly higher than those of Unicem and Panavia F used to uncoated dentin surfaces (P<.0001). Conclusion: Application of a resin coating to the dentin surface significantly improved the shear bonding strength of a self adhesive resin cement in indirect restoration.