Colour parameters and shade correspondence of CAD-CAM ceramic systems.
OBJECTIVE
To evaluate colour differences between (1) CAD-CAM ceramic systems considering shades A1, A2 and A3 and the corresponding nominal shade of VC (Vita Classical shade guide) and (2) shades A1-A2, A2-A3 and A1, A2 and A3 within the same ceramic system.


METHODS
Samples of shades A1, A2 and A3 were fabricated (n=5) from CAD-CAM ceramic blocks (IPS e.max(®) CAD LT and HT, IPS Empress(®) CAD LT and HT, Paradigm™ C, and VITABLOCS(®) Mark II) and polished to 1.0±0.01mm in thickness. Spectral reflectance and colour coordinates were measured using a spectroradiometer inside a viewing booth using the CIE D65 illuminant and the d/0° geometry. Spectral reflectance curves were compared using VAF coefficient and were statistically analyzed using Kruskal-Wallis and the Mann-Whitney U test (α=0.05). Colour coordinates were statistically analyzed using one-way ANOVA, Tukey's test with Bonferroni correction (α=0.001). All colour differences (ΔEab(*) and ΔE00) were analyzed through comparisons with the PT - perceptibility and AT - acceptability thresholds for dental ceramics.


RESULTS
ΔE between ceramic systems and its corresponding shade ranged from 6.32 to 13.42 (ΔEab(*)) and 4.48 to 9.30 (ΔE00). ΔE between shades A1-A2, A2-A3 and A1, A2 and A3 ranged, respectively, 1.93-4.82, 1.22-5.59 and 3.63-8.84 (ΔEab(*)); 1.54-3.87, 1.03-3.90 and 2.95-6.51 (ΔE00).


CONCLUSIONS
Considering the corresponding nominal shade from VC, none of the ceramic systems showed colour differences below the AT. In addition, some ceramic systems showed colour differences below AT (shades A1-A2 and A2-A3) and below PT (shades A2-A3).


CONCLUSIONS
Careful adjustments should be made to the final shade of CAD-CAM ceramic restorations to reach a clinically acceptable shade match.
Post-graduate Program in Dentistry, Dental School, University of Passo Fundo, Brazil. Electronic address: dbona@upf.br.
Alvaro
A
Della Bona
Post-graduate Program in Dentistry, Dental School, University of Passo Fundo, Brazil; Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva, Edificio Mecenas, s/n, 18071 Granada, Spain.
Oscar E
OE
Pecho
Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva, Edificio Mecenas, s/n, 18071 Granada, Spain; Houston Center for Biomaterials and Biomimetics, Department of Restorative Dentistry and Prosthodontics, University of Texas, School of Dentistry, 7500 Cambridge St., Houston, TX 77054, USA.
Razvan
R
Ghinea
Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva, Edificio Mecenas, s/n, 18071 Granada, Spain.
Juan C
JC
Cardona
Department of Optics, Faculty of Science, University of Granada, Campus Fuente Nueva, Edificio Mecenas, s/n, 18071 Granada, Spain; Houston Center for Biomaterials and Biomimetics, Department of Restorative Dentistry and Prosthodontics, University of Texas, School of Dentistry, 7500 Cambridge St., Houston, TX 77054, USA.
María M
MM
Pérez
D002516:Ceramics / Q000737:chemistry*; D003116:Color; D003124:Colorimetry / Q000295:instrumentation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry*; D017076:Computer-Aided Design; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D017797:Prosthesis Coloring; D013499:Surface Properties
D003188:Composite Resins; D003764:Dental Materials; D003776:Dental Porcelain
Colour; Dental ceramics; Reflectance