title: Masking ability of zirconia with and without veneering porcelain.
abstract: OBJECTIVE
  The present study compared changes in CIE L*a*b* color coordinates of substrates of different colors when covered with zirconium oxide discs (Procera) and with such discs if veneered with two shades of porcelain.
  
  
  METHODS
  Forty background substrates were fabricated and divided into four groups depending on the color of the substrates: white, black, gray, and tooth-colored (Vita shade A3). The initial color of the substrates was measured using a colorimeter. The color of the substrates covered with plain zirconium oxide discs and with zirconium oxide discs veneered with porcelains of two shades (Vita shade A1 and B4) was measured. The color difference between the substrates, the substrates covered with plain discs, and the substrates covered with veneered discs was calculated, and the data were statistically analyzed with one-way ANOVA and multiple paired t-test.
  
  
  RESULTS
  For each group of substrates, the resulting colors were significantly different when the substrates were covered by either plain zirconium oxide discs or zirconium oxide discs veneered with Vita shade A1 or B4 porcelain.
  
  
  CONCLUSIONS
  While zirconium oxide coping material alone has a degree of masking ability, the resulting color of a restoration can be further modified with the veneering porcelain.
authors: Department of Dentistry, Korea University Medical Center, Seoul, South Korea.
authors: Yeon-Jo
authors: YJ
authors: Choi
authors: Michael E
authors: ME
authors: Razzoog
mesh_terms: D003116:Color; D003124:Colorimetry / Q000295:instrumentation; D003723:Dental Amalgam / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003801:Dental Veneers; D006801:Humans; D008422:Materials Testing; D008768:Methylmethacrylates / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D008768:Methylmethacrylates; D012117:Resins, Synthetic; C069716:Jet, dental resin; D003776:Dental Porcelain; D003723:Dental Amalgam; C010102:delrin; D015040:Zirconium; C028541:zirconium oxide