Effects of dyes used in photodynamic therapy on color stability of composite resins

Abstract

Purpose: The aim of this study was to evaluate the effect of dyes used in photodynamic therapy (PDT) on color changes of resin-based composites (RBCs). Methods: A total of 120 composite discs were made of microfilled, nanohybrid, and nanocemmic RBCs, and the CIE Lab system was used to assess initial colors with a spectrophotometer. Photosensitizers were used in accordance with the experimental design, as follows: MB (methylene blue), TB (toluidine blue). ICG (indocyanine green), and control (no dye). The samples were irradiated with a 940-nm diode laser. After irradiation, the photosensitizers were removed with distilled water (Delta E-1) and sodium hypochlorite (Delta E-2), and final colors were measured. Data were analyzed by the three-way ANOVA and Bonferroni tests (alpha= 0.05). Results: There was no statistically significant difference between the ICG and control groups; however, the TB and MB groups exhibited the strongest staining. The nanohybrid RBC exhibited the greatest color change, and there were no significant differences between the microhybrid and nanoceramic RBCs. After NaOCl irrigation, Delta E-2 values decreased to clinically acceptable values (Delta E-2 < 3.3). Conclusion: The intensity of staining of the RBCs differed according to the type of photosensitizer used and the content of the composite resin. The irrigant NaOCl was effective in removing discoloration.