Development of Thickness-Dependent Predictive Methods for the Estimation of the CIEL*a*b* Color Coordinates of Monolithic and Layered Dental Resin Composites

Usually, dentin and enamel shades are layered in dental restorations with the purpose of mimicking the natural appearance of teeth. The main objective of this study was to develop and assess accuracy of a color-prediction method for both monolithic and layered dental resin-based composites with varying shades and under different illuminants. A total of 15 different shades of VITAPAN Excell, VITAPAN Dentine and VITA Physiodens as well as VITA Enamel of five different thicknesses (0.5-2.5 mm range) were used to manufacture monolithic and layered samples. A non-contact spectroradiometer with CIE 45 degrees/0 degrees geometry was used to measure the color of all samples over a standard ceramic black background. Second-degree polynomial regression was used as predictive method for CIE-L*a*b* color coordinates. Performance of predictive models was tested using the CIEDE2000 total color difference formula (Delta E-00), while accuracy was evaluated by comparative assessment of Delta E-00 with corresponding 50:50% acceptability (AT(00)) and perceptibly (PT00) thresholds for dentistry. A mean color difference between measured (real) and predicted color of Delta E-00=1.71, with 62.86% of the color differences below AT(00) and 28.57% below PT00, was registered for monolithic samples. For bi-layered samples, the mean color difference was roughly Delta E-00=0.50, with generally 100% and more than 85% of the estimations below AT(00) and PT00, respectively. The predictive method allowed highly accurate color estimations for both monolithic and layered dental resin-based composites with varying thicknesses and under different illuminations. These results could be useful to maximize the clinical success of dental restorations.

Automated summary

The study aimed to develop and assess a color-prediction method for dental resin-based composites with different shades and under different illuminants. The method utilized a non-contact spectroradiometer and second-degree polynomial regression to predict color coordinates. The accuracy of the method was evaluated using the CIEDE2000 total color difference formula. The results showed highly accurate color estimations for different thicknesses of resin-based composites under different illuminations.