title: Effect of immersion into solutions at various pH on the color stability of composite resins with different shades.
abstract: OBJECTIVE
  This study examined the color changes of a resin composite with different shades upon exposure to water with different pH.
  
  
  METHODS
  Nanohybrid resin composites (Filtek Z350XT, 3M ESPE) with four different shades (A2, A3, B1, and B2) were immersed in water with three different pH (pH 3, 6, and 9) for 14 day. The CIE L*a*b* color coordinates of the specimens were evaluated before and after immersion in the solutions. The color difference (ΔE*) and the translucency parameter (TP) were calculated using the color coordinates.
  
  
  RESULTS
  ΔE* ranged from 0.33 to 1.58, and the values were affected significantly by the pH. The specimens immersed in a pH 6 solution showed the highest ΔE* values (0.87 - 1.58). The specimens with a B1 shade showed the lowest ΔE* change compared to the other shades. TP ranged from 7.01 to 9.46 depending on the pH and resin shade. The TP difference between before and after immersion in the pH solutions was less than 1.0.
  
  
  CONCLUSIONS
  The resulting change of color of the tested specimens did not appear to be clinically problematic because the color difference was < 1.6 in the acidic, neutral, and alkaline solutions regardless of the resin shade, i.e., the color change was imperceptible.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
authors.forename: Ji-Deok
authors.initials: JD
authors.lastname: Moon
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
authors.forename: Eun-Mi
authors.initials: EM
authors.lastname: Seon
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
authors.forename: Sung-Ae
authors.initials: SA
authors.lastname: Son
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
authors.forename: Kyoung-Hwa
authors.initials: KH
authors.lastname: Jung
authors.affiliation: Department of Dental Materials, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
authors.forename: Yong-Hoon
authors.initials: YH
authors.lastname: Kwon
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
authors.forename: Jeong-Kil
authors.initials: JK
authors.lastname: Park
keywords: Color stability; Composite resin; Resin shade; Translucency parameter; pH