Evaluating the reliability and repeatability of the digital color analysis system for dentistry

Abstract

This study was done to evaluate the reliability of the digital color analysis system (ShadeScan, CYNOVAD, Montreal, Canada) for dentistry.Sixteen tooth models were made by injecting the A2 shade chemical cured resin for temporary crown into the impression acquired from 16 adults. Surfaces of the model teeth were polished with resin polishing cloth. The window of the ShadeScan handpiece was placed on the labial surface of tooth and tooth images were captured, and each tooth shade was analyzed with the ShadeScan software. Captured images were selected in groups, and compared one another.Two models were selected to evaluate repeatability of ShadeScan, and shade analysis was performed 10 times for each tooth.And, to ascertain the color difference of same shade code analyzed by ShadeScan, CIE L*a*b*values of shade guide of Gradia Direct (GC, Tokyo, Japan) were measured on the white and black background using the Spectrolino (GretagMacbeth, USA), and Shade map of each shade guide was captured using the ShadeScan.There were no teeth that were analyzed as A2 shade and unique shade. And shade mapping analyses of the same tooth revealed similar shade and distribution except incisal third.Color difference (ΔE*) among the Shade map which analyzed as same shade by ShadeScan were above 3. Within the limits of this study, digital color analysis instrument for dentistry has relatively high repeatability, but has controversial in accuracy. [J Kor Acad Cons Dent 33(4):352-368, 2008]

Development of polarization dental imaging modality and evaluation of its clinical feasibility

“…In order to evaluate the advantage of cross-polarized images, 5 non-polarized and 5 cross-polarized tooth color images were acquired at a time interval of 5 min from a single subject in a dark room. The camera was set as follows: (1) shutter speed, 1/80 s for non-polarized images and 1/10 s for cross-polarized images, and (2) ISO 100 and f/5.6 for both images. Both types of tooth color images were converted into Commission Internationale de l'Eclairage (CIE) L*a*b* color images using a MATLAB program, in which the standard observer was 2-degree observer, and illumination was International Color Consortium (ICC) standard profile connection space illuminant with a 16-bit fractional approximation of D50.…”

“…The discoloration of gums has also become a concern with the increasing frequency of cosmetic treatments. 1 The conventional method of evaluating tooth color is visual observation by the naked eye; however, it is impossible to obtain objective color information by this method, since any method for evaluating tooth color that involves a visual observation will provide exclusively subjective color information. Color measurement devices such as colorimeters and optical spectrometers have been used in dentistry in order to acquire quantitative color information for a specific narrow region.…”