title: Color stability of mineral trioxide aggregate and calcium enriched mixture cement.
abstract: OBJECTIVE
  To assess the effect of light irradiation and different immersion media on discoloration of white mineral trioxide aggregate (WMTA) and calcium enriched mixture (CEM) cement at different time intervals.
  
  
  METHODS
  Enamel sections of 12 teeth were removed and six cavities were prepared in each tooth. The cavities were filled randomly either with WMTA or CEM and covered with transparent sealant. Half the specimens were irradiated for 160 sec (eight exposures of 20 sec each) and the remaining were irradiated for 40 sec (two exposures of 20 sec each); digital images were taken after each exposure. The teeth were stored in phosphate buffer saline, oxygen-rich medium and glycerin (n = 4). Digital images were obtained after 1, 3, 7, 14, and 28 days. Commission Internationale de I'E'clairage (CIE) color space system and Photoshop CS5 software were used to evaluate the discoloration. The color change (ΔE) and lightness (ΔL) values was analyzed using repeated measures anova and Tukey's Tukey's honest significant difference (HSD) test.
  
  
  RESULTS
  The materials tested showed significant discoloration over time (WMT > CEM; P < 0.001). ΔE increased significantly while ΔL decreased in three media over time (P < 0.001). Greater duration of light curing caused a significant decrease in ΔL and ΔE values in both materials (WMTA > CEM; P < 0.001).
  
  
  CONCLUSIONS
  Color stability of WMTA was inferior to CEM samples after exposure to different duration of irradiation and media over time.
authors.affiliation: Dental Research Center, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Jafar
authors.initials: MJ
authors.lastname: Eghbal
authors.affiliation: Iranian Center for Endodontic Research, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Torabzadeh
authors.affiliation: Iranian Center for Endodontic Research, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Alireza Akbarzadeh
authors.initials: AA
authors.lastname: Bagheban
authors.affiliation: Dental Research Center, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. saynashams@gmail.com.
authors.forename: Sayna
authors.initials: S
authors.lastname: Shamszadeh
authors.affiliation: Dental Research Center, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Laleh A
authors.initials: LA
authors.lastname: Marvasti
authors.affiliation: Iranian Center for Endodontic Research, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Asgary
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry / Q000528:radiation effects*; D017610:Calcium Compounds / Q000737:chemistry / Q000528:radiation effects*; D003116:Color; D055117:Curing Lights, Dental; D003738:Dental Cements / Q000737:chemistry / Q000528:radiation effects*; D003743:Dental Enamel / Q000000981:diagnostic imaging / Q000187:drug effects / Q000528:radiation effects; D004338:Drug Combinations; D005899:Glass Ionomer Cements / Q000737:chemistry / Q000528:radiation effects; D005990:Glycerol; D006801:Humans; D008422:Materials Testing; D008963:Molar; D010087:Oxides / Q000737:chemistry / Q000528:radiation effects*; D010100:Oxygen; D012387:Root Canal Filling Materials / Q000528:radiation effects; D017640:Silicates / Q000737:chemistry / Q000528:radiation effects*; D013997:Time Factors; D014070:Tooth / Q000737:chemistry / Q000528:radiation effects; D014075:Tooth Discoloration / Q000000981:diagnostic imaging
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; D005899:Glass Ionomer Cements; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate; D005990:Glycerol; D010100:Oxygen
keywords: 
  CEM
  ; 
  WMTA
  ; CIE laboratory system; discoloration; irradiation