The most scientific and reliable method for deciding the tooth color is the instrumental measurement. However, such color measuring instrument shows the difference of the measuring value according to the diversified measuring condition.

This study was conducted to evaluate what effect of the labial surface irregularity of the tooth to the result of the color measured by spectrometer.

11 models of the teeth were made by injecting the A2 shade Luxatemp Automix Plus (DMG, Germany) into the impression acquired from 11 adults. Standard disk samples (15 mm diameter, 7 mm thickness) were made with same material. CIE L^*a^*b^* value was measured at the incisal, central, and gingival area of the central incisor, lateral incisor, canine and first premolar using Specbos 2100 (JETI, Germany) spectrometer. Color difference was calculated between labial surface and standard samples.

Among all models of the teeth, L^* and b^* value showed the reducing tendency as they go toward the gingival area, but a^* value showed the increasing tendency.

Color difference between model teeth and standard samples showed the most difference at the incisal area, but the gingival area showed the least difference. And the canine showed the least color difference from the comparison of standard sample, and the central incisor showed the highest difference (p < 0.01).

Although the visually detectable difference of the measuring value showed notably depending on the type and measured area (p < 0.05), L^* and a^* value showed notable differences depending more on the measured areas than on the type of the teeth.