Effects of different repolishing techniques on colour change of provisional prosthetic materials.

UNLABELLED: OBJECTIVES. To investigate repolishing effect of stained provisional prosthetic materials in vitro. METHODS. Thirty two cylindrical specimens (10 x 2 mm) were prepared for each of light-polymerized composites (Revotek LC, Rx-Create), bis-acryl composites (Structur Premium, Protemp Garant3, Luxatemp Fluorescence), methyl-methacrylate (UnifastTRAD) and ethyl-methacrylate (DentalonPlus) based provisional material using a mould. The specimens were divided into 4 groups (n=8) according to different repolishing techniques. The specimens were stored for 24 hours at 37 degrees C in distilled water, and then transferred into 4 different staining agents. The colour was measured with a spectrophotometer (Vita Easyshade) before exposure and after repolishing procedures, and colour changes (DeltaE) were calculated. STATISTICAL ANALYSIS: three-way ANOVA, Tukey HSD post-hoc test (p<0.05). RESULTS. The influence of type of provisional material, polishing procedure, food colorants and combinations of them on colour change was significant (p<0.05). After the repolishing procedures, all the specimens stored in distilled water achieved an unnoticeable colour change (DeltaE<3.7), except Dentalon Plus, Rx Create, Unifast TRAD. A similar tendency was observed in artificial food colourant solution following subsequent repolishing of the specimens. As for the red wine, all repolished specimens attained unnoticeable colour change (DeltaE<3.7), except Dentalon Plus using Rx polishing paste, Enhance polishing set or repeated glazing procedure. CONCLUSION. Repolishing was found to be an effective way to improve aesthetic appearance for provisional prosthetic materials by partially removing staining observed on the surface of the restorations.