Both conventional and flexible resins may show color alteration due to intrinsic and extrinsic factors. The aim of this study was to evaluate the color changes of the polyamid and heat polymerized acrylic denture base materials in storage of different staining solutions.

Two denture base materials were used in this study. The speciemens were stored in two staining solutions (tea, coffee), distilled water and denture cleaner. For each group, 14 speciemens (25 × 15 × 2.5 mm) were prepared. The color of speciemens was measured using a colorimeter according to the CIE L*a*b* color scale. The color changes of speciemens were evaluated before and after 7 and 30 days. All data recorded were taken by the same investigator to minimize inconstancy of technique. The data were analyzed statistically by repeated measures analysis of variance and Tukey honestly significant difference multiple comparison tests. It was found no statistically significant difference between solutions (P > 0.05).

Polyamid denture base resin displayed the greatest colour change when compared to polymetyhl methacrylate denture base resin (P < 0.001). Polyamid material indicated the highest value (ΔE: 7.28) in coffee solution for 7 days.

The colour stability of polymetyhl methacrylate denture base resin is greater than polyamid denture base resin.