Objective: To assess tooth whiteness clinically using an image analysis system and a whiteness algorithm to compare with visual shade matching.
Methodology: Images of the maxillary anterior teeth of 20 subjects were obtained using an image analysis system adapted for tooth whiteness measurement. Red, green, and blue values from each image, and Commision Internationale de l'Eclairage whiteness index (CIE WI) values were calculated. A visual shade match was also carried out using a Vitapan 3D Master 26-tab shade guide.
Results: The range of CIE WI values for image analysis and visual shade matching was 32.86-85.91 and 32.68-79.84, respectively. Limits of agreement between methods were +17.71 and -14.60 CIE WI units. The 95% confidence interval of the difference was calculated as -0.176 to +3.083. A two-tailed Student t-test with a 95% confidence level showed significant differences (p = 0.028) between the paired CIE WI values of each tooth for the two measurement techniques. As the accuracy and reliability of the image analysis system was found to be high in previous in vitro studies, the differences between the two methods were probably related to the inherent subjectivity of visual shade matching.
Conclusion: The adapted digital image analysis system could be used as an alternative to, or in conjunction with visual shade matching.