title: Comparison of the color stability of flowable and universal resin composites.
abstract: OBJECTIVE
  To evaluate the color stability of flowable resin composites after ultraviolet (UV) irradiation and thermocycling, and to compare the color stability with the corresponding shade universal resin composites of the same brand.
  
  
  METHODS
  Five specimens each (10 mm in diameter and 2 mm in thickness) of four brands of flowable and universal resin composites (shade A2) were light-cured. Baseline color was measured on a reflection spectrophotometer over a white background. Artificial aging was performed with a filtered xenon lamp (irradiation intensity: 550 W/m2) for 24 hours and then color was measured. Afterwards, thermocycling was performed for 3,000 times between 5 and 55 degrees C and color was measured again. Changes in color (deltaE*ab) and color parameters (deltaL*, deltaa*, deltab* and deltaC*ab) during the UV irradiation, the thermocycling and both aging protocols were calculated. Differences in the color change of the flowable and the universal resin composites were analyzed with two-way repeated measures ANOVA by the combination of brand and type (eight groups) of materials and aging protocol (P < 0.05).
  
  
  RESULTS
  Color changes during the UV irradiation, the thermocycling and both aging protocols were in the range of 2.3-6.8, 0.6-0.8 and 2.6-6.2 deltaE*ab units, respectively. Flowable resin composites showed higher color change during the UV irradiation and was significant in three of the four brands (P < 0.05). The same results were obtained after both aging protocols. Changes in color parameters were varied by the brand and type of resin composites (P < 0.05).
authors: Department of Dental Biomaterials Science, School of Dentistry, Seoul National University, 28 Yeongeon-dong, Jongro-gu, Seoul, Korea.
authors: Bin
authors: B
authors: Yu
authors: Yong-Keun
authors: YK
authors: Lee
mesh_terms: D003116:Color; D003124:Colorimetry; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D003799:Dental Stress Analysis; D008422:Materials Testing; D014466:Ultraviolet Rays
chemical_list: D003188:Composite Resins