Temporary fixed prosthesis materials and beverage colorants: an in vitro study

The esthetic outcome of temporary prostheses, especially those in the anterior area, is of primary importance. The purpose of this in vitro study was therefore to evaluate the color stability of 3 temporary restorative materials: self-curing (SC) acrylic resin (Tempron); heat-curing acrylic resin (SR Ivocron); and polymethyl methacrylate resin blocks (Telio CAD) machined using computer-aided design/computer-aided manufacturing (CAD/CAM) technology. The heat-curing material was polymerized with either a pressure-curing technique (PT) or a flasking technique (FT). As a result, there were 4 experimental groups: SC, PT, FT, and CAD/CAM. Sixteen specimens were prepared for each group. After polymerization or milling, all specimens were polished using a diamond polishing paste, and 1 specimen from each group was exposed to Fourier-transform infrared (FTIR) and ultraviolet visible (UV-Vis) spectroscopy before immersion. The specimens were exposed to pigmented beverage agents (coffee, cola, turmeric solution, or tea), and the color change was monitored for 4 weeks using FTIR and UV-Vis spectroscopy as well as by macroscopic observation of the specimens (n = 4 per group per immersion period). The PT specimens showed the most significant color change, followed by the SC specimens. A less significant color variation was noted in the FT specimens, and insignificant change was reported in the CAD/CAM group. The solution that had the most significant staining effect was turmeric, and the CAD/CAM resin showed the greatest color stability of the tested materials. Color stability depends on the material used, the polymerization technique, the polishing steps, the pigmentation agent, and the duration of exposure to the agent.