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4 "Hyun-Wook Ryu"
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Basic Research
Effect of infection control barrier thickness on light curing units
Hoon-Sang Chang, Seok-Ryun Lee, Sung-Ok Hong, Hyun-Wook Ryu, Chang-Kyu Song, Kyung-San Min
J Korean Acad Conserv Dent 2010;35(5):368-373.   Published online September 30, 2010
DOI: https://doi.org/10.5395/JKACD.2010.35.5.368
AbstractAbstract PDFPubReaderePub
Objectives

This study investigated the effect of infection control barrier thickness on power density, wavelength, and light diffusion of light curing units.

Materials and Methods

Infection control barrier (Cleanwrap) in one-fold, two-fold, four-fold, and eight-fold, and a halogen light curing unit (Optilux 360) and a light emitting diode (LED) light curing unit (Elipar FreeLight 2) were used in this study. Power density of light curing units with infection control barriers covering the fiberoptic bundle was measured with a hand held dental radiometer (Cure Rite). Wavelength of light curing units fixed on a custom made optical breadboard was measured with a portable spectroradiometer (CS-1000). Light diffusion of light curing units was photographed with DSLR (Nikon D70s) as above.

Results

Power density decreased significantly as the layer thickness of the infection control barrier increased, except the one-fold and two-fold in halogen light curing unit. Especially, when the barrier was four-fold and more in the halogen light curing unit, the decrease of power density was more prominent. The wavelength of light curing units was not affected by the barriers and almost no change was detected in the peak wavelength. Light diffusion of LED light curing unit was not affected by barriers, however, halogen light curing unit showed decrease in light diffusion angle when the barrier was four-fold and statistically different decrease when the barrier was eight-fold (p < 0.05).

Conclusions

It could be assumed that the infection control barriers should be used as two-fold rather than one-fold to prevent tearing of the barriers and subsequent cross contamination between the patients.

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Original Article
Microleakage of endodontic temporary restorative materials under dynamic loading
Dong-Ho Jung, Young-Sin Noh, Hae-Doo Lee, Hoon-Sang Chang, Hyun-Wook Ryu, Kyung-San Min
J Korean Acad Conserv Dent 2008;33(3):198-203.   Published online May 31, 2008
DOI: https://doi.org/10.5395/JKACD.2008.33.3.198
AbstractAbstract PDFPubReaderePub

The purpose of this study was to compare the sealing abilities of four endodontic temporary restorative materials using a methylene blue dye penetration test under dynamic loading. Standardized access cavities were prepared in forty-four intact human permanent molar teeth, and the cavities were restored with Caviton, MD-Temp, IRM, or ZOE. After thermocycling, an intermittent load of 98 N at 1 Hz was applied for 1,000 cycles to the long axis of the functional cusp of each of the teeth, which were immersed in a 1% methylene blue solution. The teeth were split in half, and the linear depth of dye penetration was evaluated according to the criteria. The results were analyzed using one-way ANOVA (p = 0.05) and Duncan's multiple range test. The results demonstrated that Caviton and MD-Temp showed significantly lower microleakage than IRM and ZOE. It was concluded that Caviton and MD-Temp exhibited better sealing ability than IRM and ZOE under dynamic loading.

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Case Report
The palato-gingival groove - anatomical anomaly occurred in maxillary lateral incisors: case reports
Hyun-Il Kim, Young-Shin Noh, Hoon-Sang Chang, Hyun-Wook Ryu, Kyung-San Min
J Korean Acad Conserv Dent 2007;32(6):483-490.   Published online November 30, 2007
DOI: https://doi.org/10.5395/JKACD.2007.32.6.483
AbstractAbstract PDFPubReaderePub

This report describes clinical cases of a palato-gingival groove on a maxillary lateral incisor with associated localized periodontal disease and pulp necrosis. The tooth of the first case was extracted because of severe bone destruction. The palato-gingival groove of the second case was eliminated using a round bur, and the resulting defect was filled with synthetic graft and covered by an absorbable membrane. Both diagnosis and treatment of palato-gingival groove were very difficult and usually extraction of the involved tooth is the treatment of choice, but combined endodontic-periodontic treatment allowed the tooth to be saved.

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Original Article
Evaluation of the radiopacity and cytotoxicity of resinous root canal sealers
Chang-Kyu Kim, Hyun-Wook Ryu, Hoon-Sang Chang, Byung-Do Lee, Kyung-San Min, Chan-Ui Hong
J Korean Acad Conserv Dent 2007;32(5):419-425.   Published online September 30, 2007
DOI: https://doi.org/10.5395/JKACD.2007.32.5.419
AbstractAbstract PDFPubReaderePub

The aim of this study was to evaluate the radiopacity and cytotoxicity of three resin-based (AH 26, EZ fill and AD Seal), a zinc oxide-eugenol-based (ZOB Seal), and a calcium hydroxide-based (Sealapex) root canal sealers. Specimens, 10 mm in diameter and 1 mm in thickness, were radiographed simultaneously with an aluminum step wedge using occlusal films, according to ISO 6876/2001 standards. Radiographs were digitized, and the radiopacity of sealers was compared to the different thicknesses of the aluminum step wedge, using the Scion image software. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of each material was determined in immortalized human periodontal ligament (IPDL) cells.

The results demonstrated that EZ fill was the most radiopaque sealer, while Sealapex was the least radiopaque (p < 0.05). AH 26, AD Seal and ZOB Seal presented intermediate radiopacity values. All the materials evaluated, except for Sealapex, presented the minimum radiopacity required by ISO standards. The cell viabilities of resin-based root canal sealers were statistically higher than that of other type of root canal sealers through the all experimental time. Further, EZ fill showed statistically lower cell viability in 24 and 48 hours compared to AD Seal and in 72 hours compared to all other resin-based root canal sealers. However, there was no correlation between the radiopacity and cytotoxicity of three resin-based root canals sealers (p > 0.05).

These results indicate that resin-based root canal sealer is more biocompatible and has advantage in terms of radiopacity.

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