Effect of different polishing time on the color stability of provisional materials: An In vitro study

Background: Provisional fixed restoration is an essential component in prosthodontics treatment. These materials may experience color change for surface roughness. To reduce it, a polishing technique is required with a time setting specified. Aims and Objectives: The aim of this study was to evaluate the effect of different polishing time on the color stability of provisional materials. Materials and Methods: One hundred and forty-four resin blocks were prepared, divided into Group A, PMMA acrylic resin and Group B, bis-acryl resin. They were polished with goat hairbrush and diamond paste. Twenty-four hours stored in distilled water and 12th day on the staining solution coffee and wine. They were measured with a spectrophotometer, analyzed, and processed with the CieLab system, to calculate color difference ∆E. Results: On the 3rd day of the immersion period, the lowest mean value was showed with 1 min polishing on Group A, showing to be statistically significant, P = 0.011. In Group B, the lowest mean value was showed with 1 min 30 s. At the 7th and 12th days immersion period, the lowest mean value was showed with 30 s polishing among the groups. Conclusions: Polishing 30 s showed the lowest ∆E values on PMMA and bis-acryl resin. Mean color differences were above the clinical acceptability threshold ∆E > 3.3. Regarding the staining agent, the highest ΔE values were observed in coffee.