Spectrophotometric and visual evaluation of peri-implant soft tissue color

AimTo spectrophotometrically and visually test whether the peri-implant mucosal color differs from the color of the natural gingiva. Material and methodsForty single implants in the incisor and premolar region of 40 patients were assessed 3-7years after implant placement. The differences of the color components lightness, chroma along red-green axis, chroma along yellow-blue axis, and the total color difference E between peri-implant mucosa and natural gingiva were measured with a spectrophotometer. The color difference between peri-implant mucosa and natural gingiva was visually evaluated by clinicians and rated as clinically visible or clinically invisible from speaking distance. The dimensions of peri-implant mucosa and gingiva at the mid-buccal aspect were evaluated by using cone-beam CT. Spearman analysis was performed to detect correlations between different variables. Two-sided t-test, ANOVA, Mann-Whitney, and Kruskal-Wallis tests were applied to detect differences between the groups. ResultsThe spectrophotometrically assessed color difference Delta E between peri-implant mucosa and natural gingiva amounted to 7.0 +/- 3.9. The peri-implant mucosa presented a significant dark, greenish and bluish discoloration in comparison with gingiva at control teeth. Clinical investigation revealed that in 60% of sites the color difference between peri-implant mucosa and natural gingiva was clinically visible from speaking distance. The threshold value Delta E for the extraoral clinical distinction of mucosal color differences measured 7.5. When comparing the groups with visible and invisible color differences with respect to the three color components, a significant difference was found only for chroma along yellow-blue axis. In the group with visible color difference, mucosa presented a bluish discoloration. Correlation analysis indicated that with an increase in mucosal thickness, a trend for smaller Delta E was found. ConclusionThe spectrophotometrically assessed color of the peri-implant mucosa revealed more dark, green and blue components compared to the natural gingiva. At 60% of the implants, peri-implant mucosal discoloration was visible from speaking distance. The sites with visible and those with invisible mucosal discolorations differed significantly only regarding the chroma along yellow-blue axis.