Application Of Oral Colorimetry Based On Camera Color Measurement System

Objective:Based on the camera colorimetric system,the color correction effects of two auxiliary tools for photo color correction were studied to improve the accuracy of dentists and technicians regarding the color communication of restorations;A comparative study was conducted to compare the range of upper anterior tooth colorimetric values of the Kunming population in Yunnan province with the colorimetric coverage of the Vita 3D master to provide objective reference opinions for the production of colour shade guides to meet the color matching of upper anterior teeth in Kunming,Yunnan province.Methods:This topic is divided into three parts:1.Create a camera colorimetric system by setting up a standard photo shooting environment and a color correction method for image analysis,and examining and analyzing its accuracy in measuring the chromaticity values of plane objects and the colour shade guides to obtain the chromaticity values of the Vita 3D master used for experiments under the camera colorimetric system.2.Each of the 26 colour shade guides of the Vita 3D master were photographed with the camera in a clinic environment,and two auxiliary tools for photo color correction were added during the taking photo to compare the color correction effects of the new white balance gray reference card and the similar colour shade guide.3.The chromaticity values of the upper anterior teeth of the Kunming,Yunnan population were measured and analyzed using a camera with similar colour shade guides,and the color coverage of the Vita 3D master under the camera colorimetric system was studied for comparison.Results:1.The color differenceΔE₀₀≤0.78 between the colorimetric value of the plane objects measured by the camera colorimetric system and the standard chromaticity value,and the color differenceΔE₀₀≤0.75 between the colorimetric value of the colour shade guides and the standard chromaticity value,are less than perceptibility threshold,that is,the color difference between the two cannot be identified by eyes.2.In the clinic environment,the average value of color differenceΔE₀₀≤1.13 between the standard chromaticity value and the value of the colour shade guides obtained by using the colour shade guides similar to the color of the target teeth as an auxiliary photo color correction tool,and the average value of color differenceΔE₀₀≤1.40between the colorimetric value of the colour shade guides and the standard value obtained using the new white balance gray reference card as an auxiliary color correction tool were less than acceptability threshold,which means that they are within the range of clinically acceptable color differences,and the color difference values of the colour shade guides are smaller than the color difference values of the gray card group.3.The results of the chromaticity value measurement of the upper anterior teeth of the population in Kunming area of Yunnan Province:L^*value:55.31～78.83,with the variation pattern:middle>neck>incisal;a^*value:-1.33～9.95,with the variation pattern:neck>incisal>middle;b^*value:10.93～26.77,with the variation pattern:middle>neck>incisal.Vita 3D master coverage range:L^*value:62.55～82.63;a^*value:-0.26～6.60;b^*value:9.97～31.14.The minimum value of L^*for natural teeth was smaller than the minimum value of the colour shade guide,and the minimum and maximum values of a^*were outside the chromatic coverage of the colour shade guide,the Vita 3D master did not completely cover the L^*and a^*values of the upper anterior teeth in Kunming,Yunnan.Conclusions:1.The camera colorimetric system measures both flat objects and the colour shade guides with high accurateness,and the colorimetric values of the colour shade guides obtained with this method can be regarded as standard values.2.Using a colour shade guide with a similar color to the target tooth as an auxiliary photo color correction tool can obtain more accurate colorimetric value information than the new white balance gray scale reference card color correction.3.For the upper front teeth chromaticity characteristics of Yunnan Kunming population,the Vita 3D master needs to be enriched with lower brightness,more reddish and greener shades of colorimetric range.