Variability of porcelain color reproduction by commercial laboratories.
BACKGROUND
Many investigations in the field of metal ceramics have examined materials, manipulative variables, and the relationship of these factors to a restoration's color. However, the effect of the artistic component of restoration fabrication is not known.


OBJECTIVE
The purpose of this study was to determine through instrumental colorimetry the variability in color reproduction for metal ceramic crowns fabricated by commercial dental laboratory technicians.


METHODS
Fifty metal ceramic crowns were fabricated on standardized metal frameworks to the same shade specifications by 5 commercial dental laboratories (n=10). Laboratory prescriptions requested that the technician match the shade and translucency of a provided Vita Lumin A3.5 shade tab. Technicians used the porcelain and technique of their own selection to match the tab. Color differences were determined by use of a colorimeter between crowns and the prescribed shade tab at middle and incisal sites. Analysis of variance was used to determine whether differences in color reproduction existed among laboratories. Where statistically significant interactions existed, the Tukey honestly significant difference test was used to determine significant differences between laboratories according to sites (alpha=.05).


RESULTS
Color reproduction was significantly different (P <.0001) among laboratories for both sites. Mean color difference from shade tabs ranged from 3.5 to 11.1 DeltaE units. All laboratories were better at matching shades in the incisal third of the crown.


CONCLUSIONS
Within the limitations of this study, the ability to reproduce the color of the target shade tab differed among laboratories. Most crowns fabricated by the laboratories in this study, when compared to the prescribed shade tab, were above the clinical threshold for an acceptable shade match under intraoral conditions (DeltaE 3.7).
Douglas
R Duane
RD
School of Dental Medicince, Southern Illinois University, Alton, Ill, USA. rodougl@siue.edu
Brewer
Jane D
JD
D000704:Analysis of Variance; D003116:Color; D003124:Colorimetry; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry* / Q000592:standards; D017267:Dental Prosthesis Design / Q000592:standards; D003800:Dental Technicians; D006801:Humans; D007754:Laboratories, Dental / Q000592:standards; D016876:Metal Ceramic Alloys / Q000737:chemistry; D009518:New York; D055656:Prescriptions; D015203:Reproducibility of Results; D014070:Tooth / Q000033:anatomy & histology
D016876:Metal Ceramic Alloys; D003776:Dental Porcelain