Assessment of gingivitis with photocolorimetry: The CIE L*, a*, and b* color parameters of human gingiva

The need to objectively measure the color of human gingiva has been the subject of many studies. However, no one has yet succeeded in measuring the true color of human gingiva. Comparative color assessments have proven inaccurate, as they are subject to lighting conditions, the variability among human observers, and variation in the topology and texture of gingiva. Direct colorimetric measurements have been impossible due to gingival tissue's natural translucency, its tendency to diffract rather than reflect incident light, and its location and surface anatomy.; Because newer spectrophotometers are capable of measuring smaller flat areas, it is now possible to measure spectral reflectance, and therefore the color, of small images. This research uses photographic images of human gingiva in conjunction with algorithms that use a known standard in imaging process to measure the true color of human gingiva. Laboratory experiments describe the photographic conditions that would reproduce colors in the range of human gingival colors without random distortions.; A model for the transformations of CIE L* a* b* color parameters, which occurs during the photographic process, is formulated. Then this technique and algorithm are tested and perfected for measuring the true CIE L* a* b* color parameters of colored standards from their photographic images. Experimental color standards are chosen to represent colors in the range of human gingival colors.; The developed technique and algorithm are then used in clinical experiments to measure and describe the true CIE L* a* b* color of gingiva in a sample of human subjects with differing degrees of clinical gingivitis. The degree of gingivitis for the volunteer subjects is also measured clinically to determine the correlation between the CIE L* a* b* color parameters of gingiva and its degree of inflammation. The investigation further tests the reliability of CIE L* a* b* parameters of gingival color as a predictor of clinical gingivitis. Finally, the responsiveness of the true CIE L* a* b* color parameters of the gingiva is tested by documenting the changes in the true CIE L* a* b* color of volunteers before and after periodontal treatment consisting of initial scaling and oral prophylaxis.