Restorative Dentistry & Endodontics

Ji-Hoon Kim

2 Articles

Color and hardness changes in artificial white spot lesions after resin infiltration: Ji-Hoon Kim, Ho-Hyun Son, Juhea Chang; Restor Dent Endod 2012;37(2):90-95. Published online May 18, 2012; DOI: https://doi.org/10.5395/rde.2012.37.2.90

Abstract PDF PubReader ePub: Objectives
The purpose of this study was to determine the effect of resin infiltration technique on color and surface hardness of white spot lesion (WSL) with various degrees of demineralization.
Materials and Methods
Ten human upper premolars were cut and divided into quarters with a 3 × 4 mm window on the enamel surface. Each specimens were separated into four groups (n = 10) and immersed in demineralization solution to create WSL: control, no treatment (baseline); 12 h, 12 hr demineralization; 24 h, 24 hr demineralization; 48 h, 48 hr demineralization. Resin infiltration was performed to the specimens using Icon (DMG). CIEL^*a^*b^* color parameters of the enamel-dentin complex were determined using a spectroradiometer at baseline, after caries formation and after resin infiltration. Surface hardness was measured by Vickers Micro Hardness Tester (Shimadzu, HMV-2). The differences in color and hardness among the groups were analyzed with ANOVA followed by Tukey test.
Results
Resin infiltration induced color changes and increased the hardness of demineralized enamel. After resin infiltration, there was no difference in color change (ΔE^*) or microhardness among the groups (p < 0.05).
Conclusion
There was no difference in the effect of resin infiltration on color and hardness among groups with different extents of demineralization.

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Microleakage of the experimental composite resin with three component photoinitiator systems: Ji-Hoon Kim, Dong-Hoon Shin; J Korean Acad Conserv Dent 2009;34(4):333-339. Published online July 31, 2009; DOI: https://doi.org/10.5395/JKACD.2009.34.4.333

This study was done to determine if there is any difference in microleakage between experimental composite resins, in which various proportions of three component photoinitiators (Camphoroquinone, OPPI, Amine) were included.

Four kinds of experimental composite resin were made by mixing 3.2% silanated barium glass (78 wt.%, average size; 1 µm) with each monomer system including variously proportioned photoinitiator systems used for photoinitiating BisGMA/BisEMA/TEGDMA monomer blend (37.5:37.5:25 wt.%). The weight percentage of each component were as follows (in sequence Camphoroquinone, OPPI, Amine): Group A - 0.5%, 0%, 1% / Group B - 2%, 0.2%, 2% / Group C - 0.2%, 1%, 0.2% / Group D - 1%, 1%, 2%.

Each composite resin was used as a filling material for round class V cavities (diameter: 2/3 of mesiodistal width; depth: 1.5 mm) made on extracted human premolars and they were polymerized using curing light unit (XL 2500, 3M ESPE) for 40 s with an intensity of 600 mW/cm². Teeth were thermocycled five-hundred times between 50℃ and 550℃ for 30s at each temperature.

Electrical conductivity (µA) was recorded two times (just after thermocycling and after three-month storage in saline solution) by electrochemical method.

Microleakage scores of each group according to evaluation time were as follows [Group: at first record / at second record; unit (µA)]: A: 3.80 (0.69) / 13.22 (4.48), B: 3.42 (1.33) / 18.84 (5.53), C: 4.18 (2.55) / 28.08 (7.75), D: 4.12 (1.86) / 7.41 (3.41).

Just after thermocycling, there was no difference in microleakage between groups, however, group C showed the largest score after three-month storage. Although there seems to be no difference in microleakage between groups just after thermocycling, composite resin with highly concentrated initiation system or classical design (Camphoroquinone and Amine system) would be more desirable for minimizing microleakage after three-month storage.

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