Changes in color and color coordinates of an indirect resin composite during curing cycle

Objectives: To measure the color changes of indirect resin composites during curing cycle and to determine the influence of shade group on these changes. Methods: one brand (belleGlass NG), divided into three shade groups (EN, OD and TL), was investigated. Resin composite was packed into a mold (BC) and was cured with a light-curing unit (C1). Secondary curing was performed in the proprietary curing chamber (C2). Color was measured at BC, C1 and C2 conditions. Changes in color and color coordinates were calculated and repeated measures three-way ANOVA was performed. Each pair of compared-condition in the curing cycle was set as a repeated variable. Results: Net curing color change (C2-BC) was in the range of 1.0-10.1 Delta E-ab* units. Based on ANOVA for the color changes, Delta E-ab* was influenced by the compared-condition, the shade group and the shade designation (p < 0.01). Changes in color coordinates varied by the shade group. Conclusion: Changes in color during curing cycle were perceptible in several shades by the condition (Delta E-ab* > 3.7); therefore, clinical practice of shade matching should consider these color changes. (c) 2008 Elsevier Ltd. All rights reserved.