The color masking ability of a zirconia ceramic on the substrates with different values

Journal of Prosthodontics

2018

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128

Monolithic zirconia restoration is an acceptable treatment option in restorative dentistry and a developing trend in esthetic dentistry. Digital dentistry has simplified fabrication of monolithic zirconia restorations. Zirconia ceramic has introduced an opportunity to achieve both esthetic and mechanical requirements for restorations. This is rarely found for a ceramic in dentistry. Monolithic zirconia restorations represent an acceptable durability, comparable to metal-ceramic restorations, while they are superior to metal-ceramic restorations esthetically; however, difficulties to gain an optimal shade reproduction and a color match with monolithic zirconia restorations still remain. The color of these restorations may be influenced by manufacturing processes, laboratory procedures, and clinical factors. Manufacturing processes determine basic optical properties of zirconia ceramics. Different laboratory procedures may create optical changes in zirconia ceramics. Also clinical factors such as dental background, cement, and zirconia restoration features may affect the resulting color. This literature review aimed to discuss potent factors in the color of monolithic zirconia restorations. An electronic search of the PubMed/Google Scholar database was performed to find related English-language articles published between January 1, 2000, and October 31, 2017. The key terms of background, cement, ceramic, color, esthetics, shade, spectrophotometry, thickness, translucency, and zirconia were used both individually and simultaneously. Also, a manual search was conducted, and five classic articles of color science were added. Thus 192 articles were included. In the last decade, shade reproduction of monolithic zirconia restorations has been highly regarded; however, further improvements are required in the manufacturing process to produce tooth-like zirconia ceramics. An esthetic guideline named background-cement-ceramic color harmony was suggested in this study; however, more clinical practice guidelines should be established for monolithic zirconia restorations on esthetics, and therefore, more studies are required.

Section: Clinical Factorsmentioning

confidence: 99%

Color Aspect of Monolithic Zirconia Restorations: A Review of the Literature

Journal of Prosthodontics

2018

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128

“…Tabatabaian et al evaluated the masking ability of a zirconia ceramic on a black and white substrate and defined a minimum thickness of 1 mm for acceptable masking ability and a minimum thickness of 1.6 mm for ideal masking ability. Tabatabaian et al indicated that a 0.5 mm framework zirconia could not show adequate color masking ability to hide grey and black substrates. Basso et al revealed that monolithic lithium disilicate‐based veneers with 0.7 to 2 mm thicknesses masked C4‐shaded substrate but could not mask metallic substrates, while bilayer structures with 0.5 mm zirconia copings and the same veneers exhibited greater shade masking ability than the monolithic structures .…”

Section: Substratementioning

confidence: 99%

Color in Zirconia‐Based Restorations and Related Factors: A Literature Review

Journal of Prosthodontics

2018

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Zirconia ceramic is a popular trend in esthetic and restorative dentistry. Computer-aided design/computer-aided manufacturing (CAD/CAM) systems have been well developed to fabricate zirconia frameworks and restorations with acceptable mechanical properties. Zirconia ceramics have excellent optical characteristics; however, achieving optimal esthetic outcomes with zirconia-based restorations is still challenging due to multiple effective factors on the final color. These factors are different layers of a zirconia-based restoration and its underlying structures including: dental substrate, cement, zirconia coping, veneering ceramic, and glaze. Moreover, the laboratory procedure of these restorations' fabrication is another effective factor on the resultant color. Unpredictable esthetic results may be obtained without estimation of the role of each factor and its effect on the final color. This review discussed the color aspect of zirconia-based restorations according to these factors and based on the literature. In the past decade, investigators have been concerned with the shade reproduction with zirconia-based restorations; however, there are no sufficient clinical guidelines on how to reproduce the appearance of natural teeth with these restorations. Zirconia-based restorations have presented a new chance for accomplishing optimum esthetics. Nonetheless further investigations are needed on these restorations to establish clinical guidelines on esthetics.

“…21 The background L * value affects the masking ability of an 0.5-mm-thick white zirconia ceramic. 22 A zirconia-based restoration commonly includes a 0.3- to 0.5-mm-thick zirconia coping and a 1-mm-thick veneering porcelain. Although an 0.4-mm-thick zirconia coping alone produces acceptable masking ability on tooth-colored backgrounds, it might be insufficient for masking metal backgrounds.…”

Section: Introductionmentioning

confidence: 99%

Effects of veneering porcelain thickness and background shade on the shade match of zirconia-based restorations

J Dent Res Dent Clin Dent Prospects

Aflatoonian²,

Namdari

2019

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Background. Effects of veneering porcelain thickness and background shade on the shade match of zirconia-based restorations are unclear. The aim of this study was to evaluate the impacts of veneering porcelain thickness and background shade on the shade match of zirconia-based restorations. Methods. Forty A2 shade veneered zirconia disk specimens (10 mm in diameter) were fabricated, with veneering porcelain thicknesses of 1.6, 1.8, 2.0 and 2.2 mm. Three backgrounds were made of A2 shade composite resin (A2), nickel-chromium alloy (NC) and amalgam (AM). The veneered zirconia specimens were placed on the backgrounds. CIELab values were measured with a spectrophotometer. ΔE values were measured to determine color differences between the specimens and the A2 VITA classical shade (target shade). ΔE values were compared with an acceptability threshold (ΔE=3.7). Repeated measures ANOVA, Bonferroni, and 1-sample t-test were used to analyze data (P<0.05). Results. Mean ΔE values ranged between 1.9 and 5.0. The veneering porcelain thickness, the background shade and their interaction affected the ΔE (P<0.0001). The minimum veneering porcelain thickness for the shade match was 2 mm for NC and 1.8 mm for AM. Conclusion. Veneering porcelain thickness and background shade affected the shade match of zirconia-based restorations. With dark-shaded backgrounds, the amount of veneering porcelain thickness needed for the shade match might be beyond acceptable clinical limits. Tooth-shaded backgrounds are esthetically advocated rather than dark-shaded backgrounds in zirconia-based restorations.