Published online Jan 31, 2002.
https://doi.org/10.5395/JKACD.2002.27.1.087
Color changes in composites according to various light curing sources
Abstract
The purpose of this study was to evaluate the color changes of composite resin polymerized with three type of light curing units. Composite resin (Z100, shade A2) were applied in a cylindrical metal mold(2 mm thick, 7 mm diameter).
Twenty specimens according to light curing units were made.
Group1: the specimens were polymerized with Apollo 95E for 3seconds(1370 mW/cm2).
Group2: the specimens were polymerized with XL 3000 for 40seconds(480 mW/cm2).
Group3: the specimens were polymerized with Spectrum 800 for 10 seconds(250 mW/cm2) and 30 seconds(700 mW/cm2).
The microhardness values(VHN) of upper and lower surfaces specimens after light polymerization were measured for the degree of polymerization. All specimens were stored in distilled water at 60℃ for 30 days.
The color characteristics(L*, a*, b*) of the specimens before and after immersion were measured by spectrophotometer and the total color difference (ΔE*) was computed.
The results obtained were as follows:
1. The microhardness values of Group I showed significantly lower than those of Group II and III(p<0.05).
2. In all groups the ΔE* values presented below 2.0.
3. Group I showed the highest ΔE* values followed order from highest to lowest by Group II and III (p<0.05).
Fig. 1
Separable cylindrical metal mold for sample fabrication
Fig. 2
Diagram of the CIE L*, a*, b* color space
Fig. 3
I: Apollo 95E, II: XL 3000, III: Spectrum 800
Graphic representating of mean microhardness values(VHN) of each group
Fig. 4
Graphic representation of the chromatic color changes of group I, II and III produced by storing for 30 days in distilled water at 60℃
Fig. 5
I: Apollo 95E, II: XL 3000, III: Spectrum 800
Total color difference(ΔE*) in group I, II and III
Table 1
Light curing units used in this study
Table 2
Microhardness values(VHN) of upper surfaces and lower surfaces of each group(Mean±SD)
Table 3
Result of color changes of group I, II and III after storing for 30 days in distilled water at 60℃ expressed as means
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