title: Changes of optical properties of dental nano-filled resin composites after curing and thermocycling.
abstract: The objective was to evaluate the color changes after curing, polishing, and thermocycling of a nano-filled resin composite. A nano-filled composite was grouped into two shades of enamel (EN) and translucent (TL). One hybrid composite was used as a control (CL). Color of specimens of 10 mm in diameter and 2 mm in thickness was measured on a reflection spectrophotometer with SCE geometry under the D65 illumination over white and black backgrounds. Color before curing and after curing, polishing and thermocycling was measured. Color change (DeltaE(*) (ab)), translucency parameter (TP), and contrast ratio (CR) were compared. Average DeltaE(*) (ab) after curing was 4.6 in the EN group and 10.4 in the TL group compare to 2.9 in CL. Polishing caused average DeltaE(*) (ab) of 3.3-3.6, which was not different by the shade group (p > 0.05). After 2000 cycles of thermocycling, average DeltaE(*) (ab) was 1.4-1.8, which was not different by the shade group (p > 0.05). TP values increased after curing in the EN group, but decreased in the TL group (p < 0.05). TP values after thermocycling decreased in the EN group but did not change in TL (p = 0.05). TP values of TL shades were higher than those of EN regardless of specimen conditions (p < 0.05). Changes in CR values showed similar trends to those of TP values in translucency. Changes of color and translucency after curing, polishing, and thermocycling varied by the shade group.
authors.affiliation: Department of Dental Biomaterials Science, College of Dentistry, Seoul National University, 28 Yeongeon-dong, Jongro-gu, Seoul, Korea. ykleedm@snu.ac.kr
authors.forename: Yong-Keun
authors.initials: YK
authors.lastname: Lee
authors.forename: Bum-Soon
authors.initials: BS
authors.lastname: Lim
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Rhee
authors.forename: Hyeong-Cheol
authors.initials: HC
authors.lastname: Yang
authors.forename: John M
authors.initials: JM
authors.lastname: Powers
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003743:Dental Enamel; D003775:Dental Polishing; D006801:Humans; D012822:Silicon Dioxide
chemical_list: D003188:Composite Resins; D012822:Silicon Dioxide