"Effect of multiple firing on the color stability, translucency and flexural strength of Amber®Press and Amber®Mill”

Abstract

This study was designed to evaluate the effect of the multiple firings on color, translucency and biaxial flexure strength of pressable and machinable lithium disilicate ceramic. The most common technique to build a restoration is to form a core then cut back the incisal area to create mamelons and characteristics by the application of various incisal porcelains then fired to attain a full contoured restoration. To produce a natural appearance with correct form and color the all ceramic restoration is fired several times. There it is crucial evaluate the effect of these firings on the restoration Twenty-one specimens were prepared into discs of 10mm diameter and 1mm thickness of Amber Press and Amber mill each were tested for color stability, translucency and biaxial flexural strength after 1st,3rd and 5th firings. The color and translucency were tested using an in-lab spectrophotometer then color stability and translucency parameter were calculated. Biaxial flexure strength was measured with a universal testing machine using piston on three ball test. The results revealed that there is statistical significance in the translucency due to the firing cycles, but Amber mill showed significantly higher translucency than Amber Press. This difference in the types of ceramics maybe due to the smaller crystal size of the Amber mill, which lead to a more translucent restoration. The color change (ΔE) was significant between the firing cycles