The Effect Of Number Of Firing Cycles On The Color Of Porcelain Fused To Metal Restoration - A Spectrophotometric Analysis

Abstract

Aim - To evaluate the changes in color of porcelain fused to metal restorations with increased number of firing cycles.

Materials and Method - Total 80 preformed metal ingot nickel chromium alloy, having dimension 13 mm in thickness and 7.6 mm in diameter were selected. Porcelain veneering of 1.5 mm thickness was done that include wash opaque, shade opaque and dentin body porcelain layer. Firing was done for each layer of porcelain application. Total 5 firings were performed that includes autoglaze. Thereafter extra firing was carried out which is considered as repeated firing. Samples were then subdivided into 4 groups according to the number of repeated firing cycles performed (0, 2, 4 and 6). Color differences were measured using spectrophotometer (Vita Easyshade Advanced 4.0) and data were expressed in CIELAB system. One way Analysis Of Variance (ANOVA) test was applied for statistical analysis.

Result – Coordinate of the CIE color space system i.e. L*, a*, b* resulted in insignificant values (p>0.05) and also the overall color difference (∆E) showed insignificant values (p>0.05).

Conclusion – The color of the porcelain fused to metal after repeated firings was not affected and slight changes which occurred were below the level of individual color perception i.e. (∆E < 3) which is considered as match in oral environment. This concludes that the increase number of firings does not change the shade of the porcelain.