• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.427-436
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• 2005

Topical application of APF gel can increase the surface roughness of resin composites and the roughened surfaces may allow increased bacterial accumulation and surface staining. Resin specimens of two proprietary resin composites, Filtek Z250(FZ) and Filtek Supreme Universal(FS), and experimental resin composites containing 0%, 3%, 6% nanofillers(E0, E3, E6) were fabricated and divided into two groups of the same number; APF treatment group and no treatment group. The amount of S. mutans adhered to specimens and the mean surface roughness(Ra) were measured. The results were as follows; 1. In no treatment group, the amount of S. mutans adhered to FS was the smallest. It was significantly different from those of FZ, E3, E6(p<0.05) although it was not significantly different from that of E0(p>0.05). 2. For all resin composites used, the amount of S. mutans adhesion in APF treatment group was significantly greater than that in no treatment group(p<0.05). 3. In APF treatment group, the amount of S. mutans adhesion was significantly different between materials(p<0.05), and increased in order of FS, FZ, E0, E3 and E6. 4. Difference of the surface roughness(Ra) between materials was not statistically significant in both no treatment group and APF treatment group(p>0.05)

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.69-75
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• 2004

The degree of the indentation damage and strength degradation for 3Y-TZP ceramics and (Y,Nb)-TZP/$Al_2O_3$ dental implant composites was investigated under the Hertzian cyclic fatigue. Fatigue tests were conducted at contact loads of 500 to 3000 N and up to $10^6$ cycles in exact in vitro environments. At 500 N, no strength degradation and crack generation was observed up to $5{\times}10^5$ contact cycles. Fatigue properties of 3Y-TZP ceramics was superior to (Y,Nb)-TZP/ㅍ composites due to stress relief caused by the phase transformation from tettagonal to monoclinic phase. As contact load increased, the drastic reduction in strength was found when the damage transition from ring to radial crack occurred. The extent of strength degradation was more pronounced in vitro environments probably due to chemical corrosion of artificial saliva through cracks introduced during large numbers of contacts.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.99-104
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• 2003

Alumina/zirconia-glass composites prepared by melt-infiltration were investigated to evaluate the influence of zirconia addition on mechanical and optical properties of the composites and glass penetration kinetics. The infiltration distance was parabolic with respect to time as described by the Washburn equation and the penetration rate constant, K, decreased due to the reduction In pore size as the amount of zirconia rose. The zirconia addition increased lightness ($L^*$) but reduced K, transmittance and color sharpness ($C^*$) It can be concluded that the zirconia addition was not effective to the mechanical properties of the composites due to the increase in porosity even though the toughness of the composites increased when zirconia was added up to 15 wt%.

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.77-86
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• 2002

Current composites are made with dimethacrylate monomers and silane-treated silica microfillers, either alone or with silane treated glass fillers The main reasons for clinical failure of dental composites are secondary caries, wear and fracture. Most of practitioner want to get a composite which is more tougher under occlusal stress, less polymerization contraction, and better handling properties in application clinically. The aim of this study was to investigate the influence of resin matrix with various flows on the physical proper-ties such as fracture toughness and degree of conversion of the experimental resins. It was hypothesized that flexible or tough resin composites can be designed by judicious choice of monomer composition Various flow resin matrices containing Bis-GMA, UDMA, and TEG-DMA were made by altering the pro-portion of the monomers. After the unfilled resins were light-cured for different light intensity, the fracture toughness(K$_{1c}$) was measured according to ASTM standard using the single edge notched geometry, and degree of conversion(DC) was measured by FTIR. And experimental composites were formulated with variations in the proportion of silanated quartz and strontium glass fillers as 60, 75, and 77wt%. Also, the physical properties of composites with various filer contents were evaluated as same manner. All resulting data were compared by ANOVA/Tukeys test at 0.05 level. The results were as follows; 1. The degree of conversion of high flow resin containing less Bis-GMA was higher than that of low flow unfilled resin 2. While the degree of conversion of unfilled resin was increased according to light intensity for polymerization, there was no significant increase with moderate and high light intensity. Also, the fracture toughness was not increased by high light intensity. 3. The fracture toughness was high in the low flow unfilled resin containing higher contents of Bis-GMA. 4. There was a significant increase for fracture toughness and a tendency for degree of conversion to be reduced when the content of fillers was increased. 5. In the experimental composites, the flow of resin matrix did not affected on the fracture toughness, even, which was decreased as increase of viscosity. These results showed that the physical properties of a dental composite could be attributed to the flow of resin matrix with relative content of monomers. Specific combination of resin monomers should be designed to fulfil the needs of specific indication for use.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.604-604
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• 2003

I. Objectives Newly-designed method was evaluated to measure the linear polymerization shrinkage of light-cured resin composites. II. Materials and Methods A resin composite(Clearfil AP-X, Kuraray, Japan) was filled into a vinyl-polysiloxan mold(1 to 8mm-depth, and 7mm-diameter). As indicators, 4 beads(Retention Beads 2 SS, GC, Japan；particle size $200{\;}\mu\textrm{m}$) were placed diagonally on the resin surface of a mold. The coordinates (x, y, z, pasition) of each indicator were measrued by a measuring-microscope after which the resin surface was irradiated by a curing-light source(Optilux 500, Demetron/Kerr, USA) for 40 sec. After 20 sec the coordinates were again measured.(omitted)

• Tribology and Lubricants
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• v.21 no.6
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• pp.268-271
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• 2005

In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji II LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15N contact force in a reciprocal sliding motion of sliding distance of 10mm/cycle at 1Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP > Surefil > Compoglass > Z100 > Fuji II LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji II LC specimen was the greatest among all resin composites. Dyract AP showed less wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light source as curing unit for composite resin restorations.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.128-135
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• 2015

Objectives: This study evaluated the effects of the resin thickness on the microhardness and optical properties of bulk-fill resin composites. Materials and Methods: Four bulk-fill (Venus Bulk Fill, Heraeus Kulzer; SDR, Dentsply Caulk; Tetric N-Ceram Bulk Fill, Ivoclar vivadent; SonicFill, Kerr) and two regular resin composites (Charisma flow, Heraeus Kulzer; Tetric N-Ceram, Ivoclar vivadent) were used. Sixty acrylic cylindrical molds were prepared for each thickness (2, 3 and 4 mm). The molds were divided into six groups for resin composites. The microhardness was measured on the top and bottom surfaces, and the colors were measured using Commission Internationale d'Eclairage (CIE) $L^*a^*b^*$ system. Color differences according to the thickness and translucency parameters and the correlations between the microhardness and translucency parameter were analyzed. The microhardness and color differences were analyzed by ANOVA and Scheffe's post hoc test, and a student t-test, respectively. The level of significance was set to ${\alpha}=0.05$. Results: The microhardness decreased with increasing resin thickness. The bulk-fill resin composites showed a bottom/top hardness ratio of almost 80% or more in 4 mm thick specimens. The highest translucency parameter was observed in Venus Bulk Fill. All resin composites used in this study except for Venus Bulk Fill showed linear correlations between the microhardness and translucency parameter according to the thickness. Conclusions: Within the limitations of this study, the bulk-fill resin composites used in this study can be placed and cured properly in the 4 mm bulk.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.132.2-132
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• 2003

• Journal of the Korean Ceramic Society
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• v.36 no.12
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• pp.1381-1389
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• 1999

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.125.2-125
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• 2002