Background and aims. To verify the color match of metal-ceramic and full ceramic crowns, using instrumental methods. Methods. A number of 153 teeth (anterior and posterior teeth), in 62 patients,  were restored with metal ceramic (MC, n=119), pressed-ceramic (PC, n=28), and zirconia-ceramic (ZC, n=6) full coverage crowns. The shade of a reference natural tooth was recorded instrumentally with a dental spectrophotometer (Vitaeasyshade Advance 4.0) in “single tooth measurement”, which provided  the base color in Vita Classic (VC) and Vita 3D Master shades (3D).  For verifying the outcome of the restoration “verify restoration” mode was used, and ΔE values were recorded for both VC and 3D Master shade guides. Moreover, matching symbols were also recorded (***=good, **=fair, *=poor). Descriptive statistics was performed and data were analyzed (One-sample z-Test, α=0.05) for comparison with visual thresholds in dentistry (Perceptibility Threshold – PT=1.2 and Acceptability Threshold – AT=2.7). Results. The data did not follow a normal distribution (Kolmogorov-Smirnov test, p<0.05). Recorded color difference was significantly higher than PT and AT, for all types of restorations, regardless of the  coding system (p<0.05). For MC crowns in 2.52% (4.20% for 3D) of the cases the color difference was smaller than PT, in 19.32% (the same for 3D) of cases was between PT and AT, and in 78.15% (76.47% for 3D) of cases was higher than the AT. For PC crowns in 3.57% (0% for 3D) of the cases the color difference was smaller than PT, in 25% (32.14% for 3D) of cases was between PT and AT, and in 71.42% (67.85% for 3D) of cases was higher than the AT. In the case of ZC crowns none of the restorations had color difference smaller than PT, but in 16.66% of cases was between PT and AT, and in 83.33% of cases was higher than the AT, for both VC and 3D. Conclusion. Within the limitations of the study, a better color match was achieved in the case of pressed ceramic crowns, made of lithium disilicate.  In most of the situations the color difference between the restoration and the reference tooth exceeded the perceptibility thresholds, but the matching was recorded as “fair” by the spectrophotometer.   

PURPOSEThe aim of this study was to define a color space of non-vital teeth and to compare it with the color space of matched vital teeth, recorded in the same patients.MATERIALS AND METHODSIn a group of 218 patients, with the age range from 17 to 70, the middle third of the buccal surface of 359 devitalized teeth was measured using a clinical spectrophotometer (Vita Easyshade Advance). Lightness (L*), chromatic parameters (a*, b*), chroma (C*), hue angle (h) and the closest Vita shade in Classical and 3D Master codifications were recorded. For each patient, the same data were recorded in a vital reference tooth. The measurements were performed by the same operator with the same spectrophotometer, using a standardized protocol for color evaluation.RESULTSThe color coordinates of non-vital teeth varied as follows: lightness L*: 52.83–92.93, C*: 8.23–58.90, h: 51.20–101.53, a*: −2.53–24.80, b*: 8.10–53.43. For the reference vital teeth, the ranges of color parameters were: L*: 60.90–97.16, C*: 8.43–39.23, h: 75.30–101.13, a*: −2.36–9.60, b*: 8.36–39.23. The color differences between vital and non-vital teeth depended on tooth group, but not on patient age.CONCLUSIONNon-vital teeth had a wider color space than vital ones. Non-vital teeth were darker (decreased lightness), more saturated (increased chroma), and with an increased range of the hue interval. An increased tendency towards positive values on the a* and b* axes suggested redder and yellower non-vital teeth compared to vital ones.

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