Evaluation of the Effect of 2 Flask Investment Materials on Color Stability of 5 Brands of Denture Teeth

The purpose of this study was to investigate the effect of flask investment materials on the color changes of different brands of resin denture teeth. Resin denture teeth (560) were divided into 2 groups according to the materials used for flask investment (silicone or gypsum). All the specimens were thermocycled between 4°C and 60°C with 60-s dwell times for 1,000 cycles. Subsequently, the specimens of each group were divided into 4 subgroups based on the immersion media: coffee, tea, cola, and distilled water. Digital images of the teeth were taken before immersion and 30 days after immersion. The color samples were measured using the CIE L*a*b* system, and color differences (∆E) were calculated. The data were evaluated by three ways ANOVA and the Tukey HSD test. There was not a significant difference in ∆E using three-way ANOVA, while the results showed considerable statistical differences with two factor ANOVA interaction. The ∆E values in the silicone group were significantly more than those in the gypsum group (P<0.001). Among the solutions in which specimens were kept, maximum discoloration was seen with coffee followed by cola, tea, and distilled water. The Ivoclar Vivadent denture teeth in the silicone group, as well as the Apple teeth in the gypsum group exhibited the highest level of color stability. All test groups exhibited visually perceptible color changes; the denture teeth and flask investment materials, as well as the nutritional habits, significantly affected the color stability of the resin denture teeth.