• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.93-96
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• 2012

PURPOSE. The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. MATERIALS AND METHODS. A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical significance was determined using two-way ANOVA (${\alpha}$=.05). RESULTS. ANOVA revealed that thickness of zirconia and light curing unit had significant effects on light transmittance ($P$ <.001). CONCLUSION. Greater thickness of zirconia results in lower light transmittance. Light-emitting diodes light-curing units might be considered as effective as Plasma arc light-curing units or more effective than Quartz-tungsten-halogen light-curing units for polymerization of the resin-based materials.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.217-230
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• 1994

The purpose of this study was to assess the 24-hour shear bond strength of amalgam to glass ionomer cement, using five different intermediaries. The intermediaries used in this study were Scotchbond 2 (light curing dentin adhesive), Panavia (resin cement), liquid' of glass ionomer cement (chemical curing & light curing), and uncured mixture of light curing glass ionomer cement. This study was operated with 48 specimens devided into 6 groups. The experimental groups are as follows: Group 1 : Bonded Amalgam to chemical curing glass ionomer cement with liquid of chemical curing glass ionomer. Group 2 : Bonded Amalgam to light curing glass ionomer cement with liquid of chemical curing glass ionomer. Group 3: Bonded Amalgam to light curing glass ionomer cement with resin cement. Group 4: Bonded Amalgam to light curing glass ionomer cement with light curing dentin adhesive. Group 5: Bonded Amdlgam to light curing glass ionomer cement with liquid of light curing glass ionomer. Group 6: Bonded Amalgam to light curing glass ionomer cement with uncured mixture of light curing glass ionomer cement. 30 minutes after amalgam condensation, all specimens were stored for 24 hours in water at $37^{\circ}C$ and tested with Instron (1122). The following results obtained: 1. The shear bond strength of group 6 was higher than those of the other groups (46.7 kgf/$cm^2$, p<0.05). 2. The shear bond strength of resin cement intermediary group was lower than that of the group using uncured mixture of light curing glass ionomer cement. 3. The results of group 1 and group 2 were different, even though the inter-me diaries used were same. 4. Intermediary of Group 5 did not show complete set in Scanning Electromicroscopic examination. 5. Light-curing dentin adhesive did not show any bonding ability to amalgam.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1057-1060
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• 2004

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 15 N contact force in a reciprocal sliding motion with sliding distance of 10 mm/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 ＆gt; Surefil ＆gt; Compoglass ＆gt; Z100 ＆gt; 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 the least 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 a curing unit for composite resin restorations.

• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.177-181
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• 2019

The purpose of this study was to investigate the degree of blocking of blue light of the tips and goggles of the curing light during the dental treatment using the blue light of the light curing. The light curing tips and goggles were placed on a UV-Vis spectrometer and the results of light transmission were analyzed. Comparative analysis. As a result, all four types of light curing tips used in the analysis showed excellent blue light blocking effect. In the case of safety goggles, red-type goggles showed blue light transmittance similar to those of light curing than yellow-type goggles. As a result, it is recommended that the attachment of the light curing with high degree of blue light blocking and the wearing of safety glasses are necessary to protect the eyes. This behavior is thought to reduce persistent irritation and fatigue in the eyes.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.638-642
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• 2001

Recently, plasma arc curing system for curing resin composites has been introduced. This is characterized by a high output of light energy, which has the advantage of reducing the chair time and thereby making the treatment more comportable for the patients as well as for the dentist. The purpose of this study was to compare the shear bond strengths of light-cured orthodontic adhesive polymerized with conventional halogen light and plasma arc light. The 2 curing devices used were the XL3000 (3M, USA) conventional curing light and the Flipo (LOKKI, France) plasma arc light. The results from the present study can be summarized as fellows; 1. The mean shear bond strength for three groups were quite similar for 50 second conventional light group, 2 second plasma arc curing light group, 5 second plasma arc curing light group. 2. There was no statistically significant difference for three groups(p>0.05).

• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.9-15
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• 2007

As the development of nanotechnology, the use of composite resins which containing nanofillers becomes popular. The purpose of this study was to test the degree of polymerization of nanofillercontaining composite resins. For the study, three different nanofiller-containing composite resins and two different light-curing units were used. To evaluate the degree of polymerization, the maximum polymerization shrinkage taking place during the light curing, and the microhardness, after the light curing, were measured. As results, two light-curing units exhibited a similar emission spectrum to that of the included photoinitiator, camphorquinone. The only difference between the light-curing units were the width of the emission spectrum. Three different composite resins showed different microhardness values. Among them, Grandio showed the greatest microhardness value. However, there was less microhardness difference on the top and bottom surfaces due to the difference of the light-curing units. The maximum polymerization shrinkage values were also similar in the tested specimens regardless of the difference of the light-curing units. However, Grandio showed the least polymerization shrinkage. According to the manufacturers' data, Grandio showed the highest filler content(vol%).

• The korean journal of orthodontics
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• v.36 no.3 s.116
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• pp.198-206
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• 2006

With the introduction of the xenon plasma arc curing light and the LED curing light as orthodontic curing lights, the polymerizing time of orthodontic composites has clearly decreased. In contrast to various research cases regarding the polymerization time and bond strength of the xenon plasma arc curing light, not enough research exists on the LED curing light, including the appropriate polymerization time. The objective of this research was to compare the bond strength of the plasma curing light and the LED curing light in regards to the polymerization time. The polymerization time needed to achieve an appropriate adhesion strength of the bracket has also been studied. After applying orthodontic brackets using composite resin onto 120 human premolars, the plasma arc curing light and the LED curing light were used for polymerization for 4, 6, and 8 seconds accordingly. This research proved that the LED curing light provided appropriate bond strength for mounting orthodontic brackets even with short seconds of polymerization. The expensive cost and large size of the device limits the use of the plasma arc curing light, whereas the low cost and easy handling of the LED curing light may lead to greater use in orthodontics.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.299-308
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• 2000

The purpose of this in vitro study was to evaluate the microleakage of 5 curing methods in class V composite restorations which are composed of two-step light curing, pulse-delay cure, low curing-light intensity, moderate curing-light intensity and high curing-light intensity. In this study, class V cavities were prepared on buccal and lingual surfaces of 50 extracted human upper or lower molars on cementum margin. Single Bond adhesive and Z-100 shade A2 were applied for each group following the manufacture's instruction. The experimental teeth were randomly divided into 5 groups of 10 samples (20 surfaces) each. Group 1: two-step light curing; Group 2: pulse-delay cure; Group 3: low curing-light intensity; Group 4: moderate curing-light intensity; Group 5: high curing-light intensity. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen was then observed with a stereomicroscope at ${\times}20$. The composite resin/tooth interfaces were examined under Scanning Electron Microscopy. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA and Dunn's Method. The results of this study were as follows. 1. In all groups, the leakage values seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 2. No group in this study showed significant differences in leakage values at both the enamel and the dentin margins(P<0.05). 3. In all groups, the gaps seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 4. The gaps in this study showed significant differences and two-step light-curing and low curing-light intensity produced significant less gap than high curing-light intensity(P<0.05).

• 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.

• Journal of dental hygiene science
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• v.19 no.2
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• pp.133-140
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• 2019

Background: The light-emitting diode (LED) curing light used is presumed to be safe. However, the scientific basis for this is unclear, and the safety of LED curing light is still controversial. The purpose of this study was to investigate the effect of LED curing light irradiation according to the conditions applied for the polymerization of composite resins in dental clinic on the cell viability and inflammatory response in Raw264.7 macrophages and to confirm the stability of LED curing light. Methods: Cell viability and cell morphology of Raw264.7 macrophages treated with 100 ng/ml of lipopolysaccharide (LPS) or/and LED curing light with a wavelength of 440~490 nm for 20 seconds were confirmed by methylthiazolydiphenyl-tetrazolium bromide assay and microscopic observation. The production of nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$) was confirmed by NO assay and $PGE_2$ enzyme-linked immunosorbent assay kit. Expression of interleukin $(IL)-1{\beta}$ and tumor necrosis factor $(TNF)-{\alpha}$ in total RNA and protein was confirmed by reverse transcription polymerase chain reaction and Western blot analysis. Results: The LED curing light did not affect the viability and morphology of normal Raw264.7 cells but affected the cell viability and induced cytotoxicity in the inflammation-induced Raw264.7 cells by LPS. The irradiation of the LED curing light did not progress to the inflammatory state in the inflammation-induced Raw264.7 macrophage. However, LED curing light irradiation in normal Raw264.7 cells induced an increase in NO and $PGE_2$ production and mRNA and protein expression of $(IL)-1{\beta}$ and $(TNF)-{\alpha}$, indicating that it is possible to induce the inflammatory state. Conclusion: The irradiation of LED curing light in RAW264.7 macrophage may induce an excessive inflammatory reaction and damage oral tissues. Therefore, it is necessary to limit the long-term irradiation which is inappropriate when applying LED curing light in a dental clinic.