Influence of manufacturing technique on the color of zirconia restorations: Monolithic versus layered crowns

Abstract

Objectives The study aimed to compare the color of monolithic and layered zirconia crowns fabricated using different brands in the cervical, middle, and incisal areas. Materials and Methods A total of 45 crowns were fabricated from three brands (Katana, Nacera, Cercon) using three methods (monolithic = ML (n=5), cut‐back + enamel = BL (n=5), cut‐back + dentin + enamel = TL (n=5)). CIE L*, a* b*, C*, h° color coordinates were recorded with a dental spectrophotometer in cervical, middle, and incisal areas. Color differences between manufacturing techniques, tooth areas, and brands were calculated using the CIEDE2000(1:1:1) formula, and the values were compared to the perceptibility (PT00) and acceptability thresholds (AT00). Comparisons between color coordinates were analyzed statistically (Kruskal‐Wallis and Mann‐Whitney U tests, p < 0.001). Results Significant differences were found between CIE L*, a*, b*, C*, h° coordinates of the zirconia crowns (p < 0.001), generally. The lowest color differences were obtained between BL and TL crowns in cervical and middle areas. Color differences between cervical and middle areas were mostly below PT00. An acceptable color difference was found between Katana and Cercon crowns. Conclusions The manufacturing technique and the brand influenced the color of zirconia crowns. Also, the color of the crowns varied from cervical to incisal. Clinical Significance Reproducing the optical properties of teeth with ceramic crowns might be challenging, given the differences in the internal configuration of the enamel and dentine, as well as their complex behavior when interacting with light. When deciding whether to fabricate a monolithic crown in translucent zirconia or improve its appearance by layering with more translucent glass–ceramic, the clinicians and dental technicians must be aware of these procedures' effect on the final color of the restorations.

Color and Translucency Variation of a One-Shaded Resin-Based Composite after Repeated Heating Cycles and Staining

“…The total color differences (ΔE 00 ) between different groups of heating cycles and for the same groups after staining were calculated using the CIEDE2000 color difference formula [ 35 , 46 ], with the same parameter values used in previous studies [ 47 , 48 , 49 ]: …”

A Comparison of Failure Loads for Polycrystalline Zirconia Ceramics with Varying Amounts of Yttria, Glass-Ceramics and Polymers in Two Different Test Conditions

“…Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) materials are a possible replacement for metal ceramic restorations because of their good mechanical properties [1,2]. However, the translucency of pure tetragonal Y-TZP has limited its use in anterior regions, where the color is affected by the resin cement and dentin underneath the crown [3,4]. Veneered porcelain has been applied on tetragonal Y-TZP copings to mask the opacity of the zirconia.…”

Comparison of Failure Loads of Polycrystalline Ceramics with Different Amount of Yttria, Glass-Ceramic, Polymers in Two Different Test Setups

“…However, the opacity of tetragonal Y-TZP has limited its use in anterior regions where the color is affected by the resin cement and dentin underneath the crown. As a result, pure tetragonal Y-TZP is not used in anterior restorations [3,4]. Veneered porcelain has been applied on tetragonal Y-TZP copings to mask the opacity of the zirconia.…”