Statistical Study of Color-Measurement Instrumentation

Abstract

In a statistical study of the variability of instrumental color-measurement data, two instruments (a Kollmorgen KCS-40 colorimeter-abridged spectrophotometer and a General Electric Recording Spectrophotometer equipped with a Davidson and Hemmendinger digital tristimulus integrator) provided three modes of measurement. Ten samples were measured 48 times in each mode. Frequency distributions were constructed for several colorimetric quantities, including tristimulus values, chromaticity coordinates, and color differences from the mean. To allow study of the error involved in the measurement of color-difference pairs, three such pairs were included in the ten samples. The beneficial effects of averaging were quantified.

Chlorhexidine with an Anti Discoloration System. A comparative study

“…For this reason the GMSI Index (25) was not used. Again sustaining that a colorimetric reading gives a more accurate measure (23,26).…”

“…To assess staining, colorimetric measurements are performed with the spectrophotometer and not the gingival modification of the stain index (GMSI; 25). In this method the tooth is divided in four zones and colour intensity in each zone is scored by the criteria described by Lobene (0, no stain; 1, light stain; 2, moderate stain and 3, heavy stain; 23, 25).…”

“…Therefore, a conditioned multifactor system was developed to automatically register the coordinated chroma without relying on the human eye. This approach consents to measure objectively the precise colour (23).…”

“…These systems were developed by the International Commission For Brightness (23). In our study, all the patients used both mouthwashes for a period of 2 weeks each, separated by an interval of 15 days, eight patients were given the mouthwash A initially and then B; seven patients were given mouthwash B initially and then A (the sequence of the mouthwashes was carried out randomly).…”

Human Perception of Dental Porcelain Translucency Correlated to Spectrophotometric Measurements

“…Many authors have evaluated human color perception correlated to instrumental measurement. Marcus and Billmeyer 28 showed a correlation between ΔE*ab values and visual assessment over a limited region. Kuehni and Marcus 29 found that 50% of subjects could detect a color difference between specimens with a ΔE*ab value of one.…”