Conventional visual vs spectrophotometric shade taking for porcelain-fused-to-metal crowns: a clinical comparison

This study tested the shade match of single porcelain-fused-to-metal restorations with the adjacent dentition when the restorations were fabricated according to data from conventional visual shade matching or from a new spectrophotometric system. The samples of a Vita Classic shade guide were measured with the spectrophotometer to determine the CIE L*a*b* color parameters. Three clinicians independently selected the best match to a maxillary right or left incisor needing a restoration in 10 patients. The 10 incisors were then measured using a reflectance spectrophotometer. CIE L*a*b* coordinates were directly recorded on the spectrophotometer's detector area using a standard light source. Resulting conventional and spectrophotometric restorations were tested intraorally for best match with the adjacent incisor using conventional shade matching versus spectrophotometric measuring. Total color difference was calculated, and all groups were statistically analyzed. Initial shade evaluation matched for all three visual shade selections in two cases. In six cases only two evaluators matched, and in the remaining two cases all three visual selections differed. In contrast, in nine of 10 cases all three spectrophotometric shade selections matched. Additionally, in nine of 10 cases delta E values of visually assessed tooth shades were higher than spectrophotometrically assessed delta E values. Resulting delta E values for conventional crowns compared to spectrophotometric crowns were significantly higher. Finally, in nine of 10 cases spectrophotometric crowns were preferred over conventional crowns for definitive cementation when evaluated visually. Spectrophotometric shade analysis and communication can be used efficiently for fabrication of porcelain-fused-to-metal restorations.