title: Color changes in resin cement polymerized with different curing lights under indirect restorations.
abstract: OBJECTIVE
  The aim of the study was to investigate the effects of different interface materials and curing units on color changes in a resin cement material.
  
  
  METHODS
  Three interface materials and different curing systems, quartz-tungsten-halogen and polywave and monowave light-emitting diode (LED) light curing units, were studied at two-time intervals. Polystyrene strip was used as a control group. All measurements were made on a white background for standard color measurement. According to the CIE L*a*b* color space, the baseline color values of each specimen were measured. Differences between the measurements were calculated as ΔE, ΔL, Δa, and Δb. Data were analyzed using analysis of variance (ANOVA) and Duncan's tests (α = 0.05) with SPSS 20.0 software (SPSS Inc., Chicago, IL, USA). ANOVA revealed significance for interface materials and curing units and time for ΔE (P < 0.05).
  
  
  RESULTS
  Interaction between polymerizing units, material and time was not significant (P > 0.05). Monowave LED exhibited significantly higher color changes than the other units ([P < 0.05] [ΔE 2.94 ± 0.44]). QTH promoted composite specimens significantly less color change ([P < 0.05] [ΔE 0.87 ± 0.41]).
  
  
  CONCLUSIONS
  This study concluded that color of resin cement used in the adhesion of indirect restorations was affected by curing device light and indirect restoration material type.
authors.affiliation: Department of Prosthetic Dentistry, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
authors.forename: Funda
authors.initials: F
authors.lastname: Bayindir
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
authors.forename: Nurcan Ozakar
authors.initials: NO
authors.lastname: Ilday
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
authors.forename: Yusuf Ziya
authors.initials: YZ
authors.lastname: Bayindir
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
authors.forename: Ozcan
authors.initials: O
authors.lastname: Karataş
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
authors.forename: Aysel
authors.initials: A
authors.lastname: Gurpinar
keywords: Color change; curing unit; indirect restoration; resin cement