Color distribution of three regions of extracted human teeth

Knowledge of human tooth color and its distribution are critical to the understanding of shade matching in esthetic dentistry. The color of human teeth shows a gradation from the gingival to the incisal region. There have been many reports in the literature on the distribution of color in teeth, but not in the CIE 1976 L*a*b* system. This study was conducted to determine the color distribution in three regions in a sample of human teeth and express the results in Munsell notation, CIE 1976 L*a*b* and CIE delta E* color differences. The hypothesis of this research was that it is possible to detect significant differences in the color parameters of the three distinct regions in teeth.

All of the teeth used in this study were extracted, cleaned and stored in artificial saliva. Prior to measurement, the teeth were removed from the solution and mounted in a holder to ensure consistent measurements. Spectral data were collected using a GE recording spectrophotometer, CIE chromaticity coordinates calculated using CIE illuminant C and 1931 observer data, and conversions made to L*, a*, b* and Munsell notation. The results were analyzed by ANOVA and Scheffé's multiple comparisons test.

The mean L*, a*, b*s were 72.6, 1.5, 18.4 for gingival, 72.4, 1.2, 16.2 for middle, and 71.4, 0.9, 12.8 for incisal. Average Munsell parameters were 1.2 Y 7.1/2.7 for gingival, 1.3 Y 7.1/2.4 for middle, and 1.4 Y 7.0/1.9 for incisal. The mean CIE delta E* between the gingival and incisal regions of the 95 teeth showed a clinically significant difference of 8.2.

The distribution of color was identified for three regions of the tooth. A statistical analysis determined that there are statistically significant color differences between the regions, and these differences are also clinically significant. This information is beneficial when esthetic restorations are required.