Abstract
The purpose of this study was to investigate the influence of the structural differences of color measuring instruments, background colors and the thickness of composite resins on the chromatical values of composite resins.
Composite resin disks which were 10 mm in diameter and 1 mm and 2 mm in thickness were made using the 3M Co. light-cured composite resin Silux Plus (shades: U, Y, DY, L, G, UO, YO). The specimens were stored in 37°C artical saliva. Chromatical values of the specimens were measured first without a background color and then against a white plate 1 day,1 week,1 month,2 months,3months,6 months,9 months and 1 year after curing. Color measuring was performed with the Murakami Color Research Laboratory Fast Spectrophotometer CMS-500 and the Flexible Sensor FS-3 (CMS-5), CMS-500 and the Flexible Sensor FS-1 (CMS-2), and the Murakami Color Research Laboratory Color Difference Meter CD-270 and the Improved Light Guide CD-270 (CD-270 Improved). The diameters of the head which receives the light from the object were: FS-3 (5 mm), FS-1(2 mm), and Improved Light Guide CD-270 (2 mm). The CIE 1976 L*a*b* color difference formula was used for the color specification.
1) In the case of both the 1 mm and 2 mm thick composite resin disks measured with or without background color, compared to the 1 day ΔE*ab values, the one-year ΔE*ab values of most shades were over 1.2 in all cases measured with the CMS-5, CMS-2 and CD-270 Improved.
2) Since the measuring times for the same specimens were high in this study, there is a high possibility that the composite resin discolorations were caused by the radiated light from the color measuring instruments.
3) Compared to the CMS-5 and CMS-2, the precision of the CD-270 Improved was low. In the case of the CD-270 Improved, it was hard to obtain accurate color changes for the composite resins over specified pericds of time, especially in the chromatical measuring of the a* values.
4) In the case of the CMS-5 and CSM-2, accurate color changes of the composite resins over specified periods of time were obtained for both the 1 mm and 2mm thick composite resin disks measured with or without a background color. The CMS-5 and the CMS-2 proved to be a precise color measuring instrument for chromatical measuring of composite resins over the specified periods of time.
