Effect of Hydrothermal Aging and Beverages on Color Stability of Lithium Disilicate and Zirconia Based Ceramics

Abstract

Background and Objectives: All-ceramic prosthesis is widely used in modern dental practice because of its improved physico-mechanical and optical properties. These restorations are exposed to coloring agents from various nutrition and beverages in the oral cavity. Long-term color stability is critical for the success of these restorative materials. The purpose of this in vitro study was to assess the effect of common beverages and mouthwash on the color stability of lithium disilicate (LD), monolithic zirconia (MZ) and bilayer zirconia (BZ) surfaces. Materials and Method: Thirty disc-shaped specimens from each material were fabricated; each group was subdivided (n = 10) according to coffee, green tea and chlorhexidine immersion solutions. The baseline color of ceramic discs was recorded according to the CIE L*a*b* system with a portable spectrophotometer. The second measurement was recorded after 3000 thermocycling and immersion in coloring agents for 7 days. The mean color difference was calculated and data were compared with Kruskal-Wallis and Mann-Whitney post hoc tests (0.05). Results: ΔE values for LD with the immersion of coffee, tea, and Chlorhexidine gluconate (CHG) were 1.78, 2.241 and 1.58, respectively. Corresponding ΔE values for MZ were 5.60, 5.19, and 4.86; marginally higher than the clinically acceptable level of 3.5. Meanwhile, BZ showed better color stability compared to MZ with ΔE values of 4.22, 2.11 and 1.43. Conclusions: Among the ceramics evaluated, LD ceramic was found to be more color stable, while MZ ceramics displayed a higher susceptibility to discoloration. MZ and BZ ceramic colors were significantly altered with coffee immersion, while LD ceramics were more affected by green tea.

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“…the absence of a monoclinic phase, this color change may be attributed to the dissolving of glaze in an aggressive medium, which in turn affects the perception of optical properties (32)(33)(34). An amorphous material, glaze, is not resistant to aggressive external influences nor is it chemically stable (33)(34)(35). In an aggressive medium, surface ions in the glaze perish, which leads to irregularities (secondary porosity) that augment roughness -a finding that corresponds to the findings of other authors (32-34).…”

Evaluation the Effect of Different Antioxidants Applied After Bleaching on Teeth Color Stability

“…These results can be related with their colorless nature and no distinguishable color difference occurred. Due to the new focus, there are only few research that consider the effects of green tea on color stability of dental materials like lithium disilicate,zirconia based ceramics and composite resin etc [43,44]. But there is no study about the post-bleaching applications.…”

Effect of Grit-blasting on the Color Stability of Zirconia Ceramics Following Exposure to Beverages

“…Following the 28-day study period, GB specimens stored in the coffee solution showed marked changes compared to other specimens. Similarly, for zirconia specimens immersed in the coffee solution in previous studies, higher than clinically acceptable values were reported [15][16].…”

“…The current study evaluated the effect of grit-blasting on the color stability of zirconia ceramics following exposure to common beverages. Although previous studies have evaluated the color stability of zirconia ceramics, this is the first attempt to study the effect of grit blasting on the color stability of zirconia [15][16][17][18]. This was important because the acid-resistant polycrystalline structure of zirconia is resistant to etching and results in weak bonding to resin composites [4].…”