Effects of Gingival Color on Ceramic Crown Color

Objectives:

This study investigated whether a variance in gingival color affects the shade of ceramic crowns to a clinically perceptible level, and it specified the resultant colorimetric effects.

Method: 3 types of ceramic crowns (Empress II, Katana, and PFM with facial porcelain margin) were fabricated for a typodont tooth #8 in shade 0M-3 and A1. The gingiva of maxillary anterior facial region was duplicated with maxillofacial silicone in six shades. Each crown was stabilized on abutment #8 with color-clear glycerin. The CIELAB color values of crowns in three areas (2x1mm, area I, II, III: 1, 2 and 3 mm away from the gingival margin respectively) of the cervical region were measured using a dental spectrophotometer (Crystaleye, Olympus). The dL*, da*,  db*, and dE of each crown with and without gingiva were calculated. One way ANOVA and Sheffe's multiple comparison tests were used for statistical analysis.

Results: CIELAB color coordinates in area I shown in the table below.

Gingiva	Light pink	Pink	Red	Orange	Light purple	Dark brown
dE	4.75	8.16	9.01	5.10	7.47	9.03
dL*	-3.29	-5.15	-6.64	-3.81	-6.61	-7.00
da*	2.75	6.16	5.64	3.02	2.82	4.86
db*	-1.41	-1.03	-1.83	0.11	-1.55	-2.58

Distinguishable color difference dE was observed in area I (4.75-9.03) and area II (2.3-4.3). With different colored gingivae in place there was a statistically significant difference for dE among different gingival colors in area I (p<0.01) and area II (p<0.05) but not area III. Area I was the only area showed significant difference in dL* (p <0.01). There were significant difference for da* in all 3 areas (p<0.01). However, there was no significant difference for db* in any area.

Conclusion:

It was concluded that a variance in gingival color has significant effects on the color of ceramic crowns with regards to dE, dL*, and  da* but not db* in the cervical area within 3mm away from the gingival margin.