Color Difference delta E for Ideal Esthetics in All-Ceramic Crowns

Color matching in dentistry has been improved based on color science and utilization of novel color measuring instruments. However, currently there is no existing gold standard for color match threshold for all ceramic crowns in mimicking a natural tooth structure.    

Objectives: The aim of this study was to assess the color discrimination threshold by analyzing color difference dE between natural teeth and all ceramic crowns.

Methods: All intraoral color measurements were made using the dental spectrophotometer (Crystaleye, Olympus). The natural maxillary central incisors (#8 and #9) were measured in 7 areas from the cervical to the incisal for 20 patients. CIE LAB dEs between 2 contralateral central incisors were calculated. The color of 5 ceramic crowns(EX) inserted in the central incisor and considered excellent in color match were measured. Another 5 ceramic crowns(CA) considered borderline-clinically acceptable in color match were also measured. Color difference dEs were measured in the same manner as above for the ceramic crowns and contralateral intact central incisors. One way ANOVA and Scheffe's multiple comparison tests were used in statistical analysis for the mean values of dE.

Results: The mean dE between contralateral natural central incisors varies from 0.65 to 1.15. The crowns considered excellent and clinically acceptable in color match had mean dE of 1.72±0.32 and 3.31±0.89, respectively. There was a significant difference between dE values of natural and clinically accepted crowns (p<0.01), but no significant difference between dE values of natural and excellent crowns (p<0.05).

dE	Area-1	Area-2	Area-3	Area-4	Area-5	Area-6	Area-7
Natural	1.15	0.97	0.75	0.65	0.83	0.96	1.08
Crowns(EX)	2.23	1.32	1.33	1.69	1.64	1.59	2.26
Crowns(CA)	3.76	2.40	3.23	3.71	3.78	3.30	3.00

Conclusions: All ceramic crowns considered excellent in color match reproduced natural tooth color with an average of dE=1.7. This dE provides ideal esthetic color match.