The Effect of repeated firings on the color of porcelain before and after glazing

An invitro study

Abstract

Background: Repeated firings would burn off the coloring pigments.

Objectives: To evaluate and compare the effect of multiple firings on the shade of metal ceramics before and after glazing.

Methods: A total of 70 base metal alloy disks with a thickness of 0.5mm were made. Then oxidation, opaque porcelain application and firing, followed by dentin porcelain is applied to all specimens and subjected to 1^st and 2^nd dentin firings. They were subdivided into 7 groups (n= 10). 1^st group is the control group and other groups were subjected to repeated second dentin firings for 3, 4, 5, 6, 7 and 8 times and color analyzed with spectrophotometer. All the specimens were glazed and again analyzed for color.

Results: 1.The color difference was observed at 5^th firing compared to control group before glazing and at 8^th firing color changes after glazing.

Interpretation and Conclusion: Color is not noticeably affected by repeated firings.