Color Changes of a Heat-Polymerized Polymethyl-Methacrylate (PMMA) and Two 3D-Printed Denture Base Resin Materials Exposed to Staining Solutions: An In Vitro Spectrophotometric Study

Newly developed 3D-printed polymer materials are used for denture base fabrication. The aim of the present study was to evaluate the color stability of two new 3D-printed resins, a hard PPMA-based and a soft Urethane-based resin, in relation to a traditional heat-polymerized PMMA resin, which was used for comparison purposes. Specimens of the materials were immersed in five solutions (distilled water, red wine, black tea, coffee, and Coke®) for definite periods of time (one day, one week, and one month). The color measurements were carried out utilizing a spectrometer supported by a microscope and using special software. Color changes between immersion periods were calculated and statistically compared. The results showed that all types of resins were influenced during immersion periods. The heat-polymerized resin was influenced less than the others but with no significant difference to the 3D-printed hard PMMA resin. In respect to the materials compared, the discoloration effect for the 1 month immersion time was significantly more intense for the soft 3D-printed resin. In respect to the solutions’ staining effects, black tea and red wine significantly discolored all materials regardless of immersion periods. The new 3D-printed materials need further improvements for dental use.