title: [Influence of background color on chromatic value of four all-ceramic system core materials].
abstract: OBJECTIVE
  To investigate the influence of post-core background color on chromatic value of four all-ceramic system core materials at clinically appropriate thicknesses.
  
  
  METHODS
  Disc specimens of 15 mm in diameter and 0.80 mm in thickness (Empress II: Group A), and 0.50 mm in thickness (In-Ceram Zirconia core: Group B; Cercon base color zirconia core: Group C; Cercon base zirconia core: Group D) were fabricated, five in each group. Au-Pt alloy, Ni-Cr alloy and visible light cured dental composite resin (A2 color) background were prepared. Samples were put on different background and their chromatic values were measured with colorimeter (CIE-1976-L(*)a(*)b(*)). Color differences of each specimen on different background material were calculated.
  
  
  RESULTS
  The color differences among specimens of Group A on different background material were more than 1.5 (2.83 ± 0.70) which meant it could be noticeable to eyes. Those of zirconia were less than 1.5 [Group B: (0.14 ± 0.08); Group C: (0.90 ± 0.20); Group D: (0.99 ± 0.09)].
  
  
  CONCLUSIONS
  The influence of background color on Group A was noticeable to human eyes, and as a result, tooth-colored post should be used for this all-ceramic system. For the other three kinds of zirconia core materia1 system, the color differences among specimens on different background material were unnoticeable. Therefore the three all-ceramic systems have excellent color masking ability and can be used on all color background.
authors.affiliation: Department of Stomatology, Yuquan Hospital, Tsinghua University, Beijing 100049, China. m.y.g.6212@163.com
authors.forename: Yong-gang
authors.initials: YG
authors.lastname: Ma
authors.forename: Nian
authors.initials: N
authors.lastname: Zhang
authors.forename: Xu-liang
authors.initials: XL
authors.lastname: Deng
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003116:Color; D003124:Colorimetry; D003776:Dental Porcelain / Q000737:chemistry; D003801:Dental Veneers; D018020:Lithium Compounds / Q000737:chemistry; D011176:Post and Core Technique; D015040:Zirconium / Q000737:chemistry*
chemical_list: C118557:Empress 2; C485633:In-Ceram Zirconia; D018020:Lithium Compounds; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide