LUMINITA OANCEA, ALEXANDRU PETRE, MIHAI BURLIBASA, EUGENIA EFTIMIE TOTU, CORINA MARILENA CRISTACHE VARIABILITY IN COLOUR REPRODUCTION OF METAL-CERAMIC CROWNS The aim of the present study was to objectively assess the variability in color reproduction of metal-ceramic (MC) single crowns fabricated by blending different color of opaque and body ceramic in order to point out which shade of the ceramic layers influences mostly the final color of the restorations. Eight nickel-chromium ceramic metal alloy copings were fabricated, on the same cast, following by blending the ceramic for the specific A3 color as follows: one reference ceramic (R) was blended, according to the producer s recommendation, and seven tests crowns have been build-up by considering as variables each one of the two uniform opaque layers, and dentin layer. Color of each manufactured crowns was measured after the three important steps of the technological workflow: the last opaque layer, enamel-dentin correction and final glaze firing using Vita Easyshade spectrophotometer. The best final color match (color difference of deltaE=0.8) was obtained for specimen no. 5, with a lighter opaque firs layer (A1). Fabricated specimens of all groups, except for no.4, with a darker dentin layer (A 3.5), showed deltaE values between 0.8 and 2.8, in the limit of the threshold perception in the oral cavity, and were scored as good. Within the limits of the present study, we can conclude that the dentin-enamel layer mostly influences the final color of the MC crowns.
Keywords: metal-ceramic crowns, color reproduction, opaque, dentine-enamel