The Effect of Translucency and Background Variations on the Color Difference of CAD/CAM Lithium Disilicate Glass Ceramic.
Al Ben Ali, Abdulaziz.
Abstract: Statement of the problem: Replication of natural tooth color is one of the most difficult challenges in prosthetic dentistry, especially in single tooth restorations in the anterior region and when the adjacent tooth is discolored or non-vital. Purpose of the study: The purpose of this study is to compare the effect of translucency and background variations on the color difference of ... read moredifferent shades of CAD/CAM lithium disilicate glass ceramic. Materials and methods: A sample size of n=10 was suggested according to a pilot study. Lithium disilicate glass ceramic cylinders (12 mm in diameter and 13 mm in length) in three different ceramic shades (BL1, A2 and C3) were fabricated by CAD/CAM technology. Specimen disks were cut into sections of 1.2 mm thickness and 12 mm diameter. Four different combinations of translucency and background color were considered among the different shades: group 1 (HT ND1), group 2 (HT ND4), group 3 (LT ND1), and group 4 (LT ND4). Each specimen was placed against different backgrounds (ND1, ND4). A spectrophotometer was used to measure the color difference and Lab. Non-parametric tests (Kruskal-Wallis tests) were used to evaluate the color differences among the tested groups, and follow-up tests (Mann-Whitney U tests) were used with Bonferroni correction. Furthermore, for each ceramic shade, high translucency groups were compared to low translucency groups to determine the influence of translucency on color differences using a non-parametric test (Mann-Whitney U test). Results: All tested groups displayed statistical significance (P< 0.001). Significant differences were present among the tested groups of the same shade (P< 0.001). Additionally, the data revealed that there were significant differences between the high translucency and the low translucency groups (p < 0.001). Conclusion: Within the limitations of this study, it is suggested that the translucency and background color significantly influenced the lithium disilicate glass ceramic color among the BL1, A2, and C3 shades. Changing the underlying color from lighter (ND1) to darker (ND4) resulted in increased color differences.
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Posthodontics.
Advisor: Hiroshi Hirayama.
Committee: Kiho Kang, Matthew Finkelman, and Roya Zandparsa.
Keyword: Dentistry.read less