OBJECTIVES: To: 1) analyze possible differences in the CIEDE2000 lightness, chroma and hue of the gingiva at the free gingival margin (FGM) and the middle zone of keratinized gingiva (MZ) between participants with an ISFP in the maxillary anterior region and participants with natural dentition and healthy gums
and 2) examine the perceptibility/acceptability of the differences in CIEDE2000 lightness, chroma and hue and in overall color, using the Euclidean and CIEDE2000 formulae. METHODS: The L*, a* and b* color coordinates were measured in 60 adult participants (30 with an ISFP and 30 with healthy teeth and gums) using a Spectroshade™ Micro spectrophotometer. From these coordinates, the changes in lightness (ΔL'), chroma (ΔC') and hue (ΔH') CIEDE2000 between the participants with and without an ISFP were quantified. The one sample t-tests were used to test whether there were significant changes in lightness, chroma and hue between the participants with and without an ISFP, and effect size was assessed with Cohen's d. The authors examined the differences in CIEDE2000 lightness, chroma and hue, and the overall color differences between the participants in pairs (with ISFP-without ISFP), comparing results with the published perceptibility and acceptability thresholds. RESULTS: Statistically significant differences were found (p <
0.05) between participants with and without an ISFP in all color attributes at both zones, with all color attributes observed to be lower in the gingiva of participants with an ISFP. In both gingival zones, the ISFP had a large effect on lightness (Cohen's d >
0.8) and a medium effect on hue (Cohen's d between 0.5 to 0.8). The mean gingival color difference of participants with and without an ISFP was 8.72 units in the MZ and 9.60 units at the FGM, using CIEDE2000. CONCLUSIONS: CIEDE2000 lightness, chroma and hue are significantly lower in participants with an ISFP, both at the FGM and the MZ, with particularly marked differences in lightness. The average color difference between healthy gingiva next to natural teeth and the gingiva adjacent to an ISFP is clinically unacceptable. CLINICAL RELEVANCE: Gingival color needs to be considered an indicator of success, given the potential unesthetic gray show-through of transmucosal abutments with ISFPs. Unacceptable color changes caused by poorly planned ISFPs can lead patients to demand treatment be repeated with more esthetic materials or mucogingival surgery to "camouflage" the discoloration.