Effect of repeated firing on the translucency of CAD-CAM monolithic glass-ceramics.

Nejatidanesh, farahnaz and Azadbakht, kamran and Savabi, omid and Sharifi, morteza and Shirani, mohammadjavad (2020) Effect of repeated firing on the translucency of CAD-CAM monolithic glass-ceramics. the Journal of Prosthetic Dentistry..

Preview

Text 10.1016@j.prosdent.2019.10.028.pdf Download (462kB) | Preview

Abstract

STATEMENT OF PROBLEM: The effects of multiple firings on the translucency of newly introduced computer-aided design and computer-aided manufacturing (CAD-CAM) glass-ceramics have not been well evaluated. PURPOSE: The purpose of this in vitro study was to assess the changes in the translucency of high-translucency (HT) and low-translucency (LT) lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) glass-ceramics of 0.6 and 1 mm thickness during crystallization, correction, and glaze firing cycles. MATERIAL AND METHODS: Eighty specimens in 8 groups (n=10) were sectioned and polished to obtain thicknesses of 0.6 and 1 mm. The specimens were then fired in 3 cycles, and the color coordinates were measured by using a spectrophotometer after each cycle. The translucency parameter (TP) and the contrast ratio (CR) were calculated to determine the translucency level. The data were analyzed by using a statistical software program. The TP and CR data after each firing cycle were compared within each group by using repeated-measures ANOVA. Pair-wise comparisons were made by using a multiple paired t test. Comparisons between the 2 thicknesses of different materials were made by using the independent t test (α=.05). RESULTS: Repeated firings significantly increased the translucency of 0.6-mm LT-LDS and decreased the translucency of 0.6-mm HT-ZLS (P<.017). No significant changes were noted in the translucency of specimens of 1-mm thickness after repeated firings. Also, 0.6-mm-thick specimens of all materials had significantly higher translucency than 1-mm-thick specimens (P≤.001). The highest translucency was noted in HT-LDS, followed by HT-ZLS. CONCLUSIONS: Repeated firings significantly affected the translucency of LDS and ZLS CAD-CAM glass-ceramics. The translucency increased with decreasing thickness.

Actions (login required)

View Item