[Effect of staining method and sintering temperature on the color of porcelain-fused-to-metal restorations].
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.
Wang
Yan
Y
Department of Prosthodontics, Guanghua College of Stomatology, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China.
Yan
Wei-hao
WH
Zhang
Xin-chun
XC
Huang
Yue
Y
Shen
Lin-han
LH
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
D006047:Gold Alloys; D016876:Metal Ceramic Alloys; D008670:Metals; D003776:Dental Porcelain; D010165:Palladium