A long-term laboratory test on staining susceptibility of esthetic composite resin materials

Objective: To evaluate the color stability of composite resin types designed for esthetic anterior restorations when continuously exposed to various staining agents. Method and Materials: Thirty-six disk-shaped specimens were made of each of 12 composite materials (1 microfilled and 11 hybrid composites). After dry storage at 37°C for 24 hours in an incubator (INP-500, Memmert), the initial color of each specimen was assessed by a calibrated reflectance spectrophotometer (SpectroShade). Specimens were immersed in five staining solutions or dry stored (control). All specimens were kept in an incubator at 37°C for 99 days. Test solutions were changed every 14th day to avoid bacteria or yeast contamination. After 99 days of storage, spectrophotometric measurements were again performed and L*a*b* scores once more recorded to determine the color changes. Results: Wine proved to have the highest staining potential followed by coffee, tea, orange juice, and cola, which had the lowest staining potential. The highest color change measured against a white background was observed for Durafill (Heraeus Kulzer) in wine (ΔE = 62.3), while the least staining was found for Enamel HFO (Micerium) in cola (ΔE = 3.5). The highest color change measured against a black background was observed for EsthetX (Dentsply) in wine (ΔE = 46.0), while the least staining was observed for Enamel HFO in cola (ΔE = 2.5). Conclusion: Composite staining susceptibility proved to vary among composite structure and brands. Potential discoloration might be limited by dietary restriction based on such in vitro evaluation. Keywords: composite resins, esthetics, staining