Effect of Repeated Firing Cycles on Translucency and Color Stability of Three Different CAD-CAM Ceramics

Abstract

Background: Repeated firing cycles and different temperatures may adversely affect the ceramic restoration, shade and translucency, which consequently affects the esthetics as well as patient satisfaction will not be achieved leading to failure of the restoration.

Aim of the study: The purpose of this in vitro study is to see how the translucency and color stability of lithium silicate, zirconia reinforced lithium silicate, and ultra-translucent zirconia are affected by multiple fire cycles.

Material and methods: Each material cut into discs with dimension 14 x 12 x 0.5 mm, Samples will be divided into 3 subgroups each n=14., 3 sub-groups according to firing cycles in each group shade and translucency will be measured, all data will be collected, tabulated and statistically analyzed.

Results: For translucency the difference in groups was statistically significant (p=0.00). The effect number of cycles was not statistically significant (p=0.169) except for ZLS was significant. Moreover, in color change the difference in groups was statistically significant (p=0.00). The effect number of cycles was statistically significant.

Conclusions: Translucency and color of Lithium silicate and ultra-translucent zirconia are not significantly affected by repeated firing cycles all in the acceptable range, however Zirconia reinforced lithium silicate showed the highest color change near the unaccepted range with repeated firing (3.6) Repeated firing cycles have some effect on recent ceramics and should be avoided.