RESEARCH AND EDUCATION Staining and aging-dependent changes in color of CAD-CAM materials Dejan D. Stamenkovi  c, DDS, a Rubens Nisie Tango, DDS, PhD, b Ana Todorovi  c, DDS, PhD, c Duygu Karasan, DDS, PhD, d Irena Sailer, DMD, PhD, e and Rade D. Paravina, DDS, PhD f The development of computer-aided design and computer-aided manufacturing (CAD-CAM) technolo- gies has simplified the workflow for fabricating indirect dental restorations. 1 Dentists are adopting a fully digital workflow with 3D digital intraoral scanning for the chairside production of CAD-CAM restorations. This a Professional Trainee, Houston Center for Biomaterials and Biomimetics (HCBB), University of Texas School of Dentistry at Houston, Houston, Texas; Private practice, Belgrade, Serbia. b Associate Professor, Department of Dental Materials and Prosthodontics, State University of Sao Paulo (UNESP) School of Dentistry at Sao Jose dos Campos, Sao Jose dos Campos, Brazil; Visiting Scientist, Houston Center for Biomaterials and Biomimetics (HCBB), University of Texas School of Dentistry at Houston, Houston, Texas. c Teaching Assistant, Department of Prosthodontics, School of Dental Medicine, University of Belgrade, Belgrade, Serbia. d Research Assistant, Division of Fixed Prosthodontics and Biomaterials, University of Geneva, Geneva, Switzerland. e Professor and Chair, Division of Fixed Prosthodontics and Biomaterials, University of Geneva, Geneva, Switzerland. f Professor, Department of Restorative Dentistry and Prosthodontics and Director, Houston Center for Biomaterials and Biomimetics (HCBB), University of Texas School of Dentistry at Houston, Houston, Texas. ABSTRACT Statement of problem. Consumption of some beverages and aging may affect the color of dental materials used in fixed prosthodontics, but their effect on recently introduced materials is not well known. Purpose. The purpose of this in vitro study was to evaluate staining, aging, and the exposure interval on color changes of computer-aided design and computer-aided manufacturing (CAD-CAM) resin nanoceramics (RNC), polymer-infiltrated ceramic-network (PICN) materials, and lithium silicate and lithium disilicate ceramics. Material and methods. A total of 288 square-shaped, 1-mm-thick specimens prepared from Cerasmart, IPS e.max, Lava Ultimate, Shofu HC, Vita Enamic, and Vita Suprinity were polished by using laboratory and chairside methods in accordance with the manufacturers’ instructions. Color data were recorded with a benchtop spectrophotometer, and CIEDE2000 color differences (DE 00 ) were calculated. After the baseline measurements (T0), the specimens were divided into 3 groups (n=8) and exposed to staining in coffee and wine and to accelerated artificial aging. The specimens were stored in staining solutions at 37  C for 60 (T1) and 120 hours (T2). Accelerated aging was performed by using a xenon lamp weathering test chamber for a total exposure of 150 (T1) and 300 kJ/m 2 (T2). The results were analyzed by using the t test, ANOVA, and the Tukey honestly significant difference test (a=.05). Color differences of DE 00 0.8 and 1.8 corresponding to the 50:50% perceptibility threshold and 50:50% acceptability threshold were used to interpret the results. Results. As color differences (DE 00 ) between laboratory and chairside polishing were not statistically significant (T=-0.81, P=.418), only the results for chairside polished specimens were presented. Color differences for the T0-T1 comparisons ranged from 0.2 to 4.2, T0-T2 from 0.3 to 6.5, and T1-T2 from 0.1 to 2.3. ANOVA showed significance of factors and for interactions (P<.05). Lithium silicateebased and lithium disilicateebased ceramic materials were more color stable than RCN and PICN materials on exposure to coffee and red wine. Color changes greater than acceptability threshold after immersion in coffee were recorded for 3 (T0-T1), 4 (T0-T2), and 2 (T1-T2) materials. Corresponding findings after immersion in wine were 1, 3, and 0 and after artificial aging 0, 2, and 0. DE 00 and DE ab values were highly correlated (R 2 =0.97). Conclusions. No difference was found in color stability among laboratory and chairside polished specimens. Coffee caused the greatest color changes for T0-T2 interval. Staining-dependent color differences increased with increased exposure, except for IPS e.max and Vita Suprinity. For artificial aging, color change appeared to be material dependent. (J Prosthet Dent 2020;-:---) THE JOURNAL OF PROSTHETIC DENTISTRY 1