Optical Effects of Artificial Gingival Color on Ceramic Crown Shade

Objective: Soft tissue color is an important component of accurate shade matching for ceramic restorations because of the contrast between the red-violet color of the gingiva and the tooth. However, the interaction between gingival color and the shade of ceramic restorations has never been fully studied. The purpose of this study is to investigate the optical effects of altering artificial gingival color on the ceramic crown shade in the cervical area.

Method: Thirty-one all-ceramic crowns of different shades were used in this study with six different artificial gingival colors. Using a spectrophotometer, we measured the shade of the crowns in the cervical areas with each of six different artificial gingiva. The crown color in the presence of pink artificial gingiva was measured as the control and the color data of the other five artificial gingiva were compared with that of the control group, respectively. CIELAB color coordinates (L^*,a^*,b^*) were collected for each group. Color difference values DE were calculated and compared between the control group and test groups and the correlation of the artificial gingival color with the crown color was also assessed.

Result: Significant difference was detected in the mean L* and a* values of all-ceramic crowns at the cervical regions among all the 6 gingival color groups (P<0.001) and significant Pearson correlations were also found for the mean L* (r=0.987, P<0.001) and a* (r=0.856, P=0.03) values between the artificial gingiva and the ceramic crowns. The mean DE values between the control group and each of the other 5 gingival groups were all significantly larger than the clinical perceptual threshold of DE 1.6 (P<0.001).

Conclusion: Clinically detectable shade differences in the cervical region of a ceramic crown are the result of the presence of different colors of artificial gingiva.