title: [Effect of bleaching agents on the color of indirect and direct composite resins].
abstract: OBJECTIVE
  To evaluate the effect of bleaching agents on the color of indirect and direct composite resins.
  
  
  METHODS
  Five resin composite materials were tested in this in vitro study. The five composites were as follow: two indirect composite resins (Adoro SR, Ceramage) and three direct composite resins (Filtek Z350, Clearfil Majesty Esthetic, and Gradia Direct Anterior). For each material, twenty disk-shaped specimens were prepared and randomly divided into five groups according to the color parameters of specimens before bleaching treatment. The composite resin specimens were treated by one of five sample solutions which were at-home bleaching agents (10% and 15% carbarmide peroxide), in- office bleaching agents (38% H(2)O(2) and 35%H(2)O(2)) and deionized water (control group). The color parameters of specimens were measured by spectrophotometer at baseline and after bleaching treatments. The color differences (ΔE values) between baseline and post-treatments were calculated. The data of color differences were evaluated statistically using two-way analysis with a significance level of 0.05.
  
  
  RESULTS
  The color changes of the resin composites were less than 2.0 after bleaching agent treatment, therefore were not perceptible. Slight increase of L(*) values and decrease of C(*)ab values in color parameters of specimens were observed. There were statistically significant differences in ΔE values for different bleaching treatments and resin materials (P = 0.001).
  
  
  CONCLUSIONS
  The bleaching agents did not affect the color of indirect and direct composite resins tested.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology & Key Laboratory of Oral Biomedicine Ministry of Education, School of Stomatology, Wuhan University, Wuhan 430079, China.
authors.forename: Wenzhong
authors.initials: W
authors.lastname: Xing
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Prosthodontics, School of Stomatology, Wuhan University, Wuhan 430079, China. Email: wang.yn@whu.edu.cn.
authors.forename: Yining
authors.initials: Y
authors.lastname: Wang
mesh_terms: D057886:Bleaching Agents / Q000737:chemistry*; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D006861:Hydrogen Peroxide; D008422:Materials Testing; D010545:Peroxides; D017640:Silicates
chemical_list: D057886:Bleaching Agents; D003188:Composite Resins; C470230:Gradia; D010545:Peroxides; D017640:Silicates; C574687:ceramage; C541508:clearfil majesty; C533204:filtek Z350; D006861:Hydrogen Peroxide