The Effect of Different Polishing Procedures and Re-polishing on the Color Stability of Single-shade Composite Resin

Purpose: The aim of this study is to evaluate the effect of different polishing systems on the color stability of single-shade composite resin after coffee immersion, brushing cycles, and re-polishing. Materials & Methods: A total of 40 disc-shaped single-shade composite resin (Omnichroma, Tokuyama, Japan) specimens were prepared using a standard mold. One-step (OneGloss, Shofu, USA), two-step (Clearfil Twist Dia, Kuraray, Japan), multi-step (OptiDisc, Kerr, USA) polishing systems were applied to each group (n=10) in accordance with the manufacturer's instructions. No polishing procedure was applied to the Control group. Representing 6 months and 1 year of clinical use, specimens were immersed in coffee solution (6–12 days) and subjected to brushing cycles (5000–10000 cycles). The specimens were then re-polished by applying the same polishing procedures as initially applied. Color measurements were repeated in all periods, and color change values were calculated with the CIEDE2000 formulation. Kruskal-Wallis analysis was used for between group comparison, and the Mann-Whitney U test was used as a post-hoc test. Statistical significance was accepted as p