title: [Effect of staining method and sintering temperature on the color of porcelain-fused-to-metal restorations].
abstract: OBJECTIVE
  To investigate the effect of staining method and sintering temperature on the color of porcelain-fused-metal restorations.
  
  
  METHODS
  40 cylindrical stained porcelain-metal specimens of 15 mm in diameter and 6 mm in height were fabricated with customized mould, consisting of 2 mm Ni-Cr metal, 1 mm opaque porcelain, 2 mm dentine porcelain and 1 mm enamel porcelain. The specimens were prepared by 5 techniques, 8 for each group. Group A: internal staining, Group B: external staining, 900 degrees centigrade sintering temperature was used in both A and B group; Group C to E: external staining, with the sintering temperature of 880 degrees centigrade, 900 degrees centigrade and 920 degrees centigrade respectively. Sofu A2 porcelain and Sofu 44 stain system were used for the study. Using standard white plate as a reference, colors (L*,a*,b* coordinates) of the specimens were measured with a computerized colorimeter. Student's t test and one way ANOVA were used to analyze the data.
  
  
  RESULTS
  DeltaE, b* and Delta C(ab)* of Group B (external staining) and group A (internal staining) were 43.72 +/- 2.99/26.51 +/- 1.64/31.31 +/- 2.48 and 39.71 +/- 1.78/23.69 +/- 0.36/26.55 +/- 2.16, respectively. The values of the former group were significantly higher than that of the latter (P < 0.05); For Group C to E, there were no significant differences in all the color parameters.
  
  
  CONCLUSIONS
  Staining method has a significant effect on the color parameters of porcelain-fused-to-metal restorations; For external staining, within the clinically-used range, changing the sintering temperature does not have an obvious effect on the color.
authors.affiliation: Department of Prosthodontics, Guanghua College of Stomatology, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Wei-hao
authors.initials: WH
authors.lastname: Yan
authors.forename: Xin-chun
authors.initials: XC
authors.lastname: Zhang
authors.forename: Yue
authors.initials: Y
authors.lastname: Huang
authors.forename: Lin-han
authors.initials: LH
authors.lastname: Shen
mesh_terms: D003116:Color; D003124:Colorimetry; D003776:Dental Porcelain; D058250:Dental Restoration Repair; D006047:Gold Alloys; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D008670:Metals; D010165:Palladium; D013194:Staining and Labeling; D013499:Surface Properties; D013696:Temperature
chemical_list: D006047:Gold Alloys; D016876:Metal Ceramic Alloys; D008670:Metals; D003776:Dental Porcelain; D010165:Palladium