Comparison and evaluation of color stability and flexural strength of various provisional restorative materials after bleaching: An in vitro study

Aims: The purpose of this in vitro study was to evaluate and compare the effect of bleaching (16% carbamide peroxide) on color stability and flexural strength of DPI Self-Cure Tooth Moulding Powder, Protemp 4, and Revotek LC. Materials and Methods: Disc-shaped 10 samples were prepared for each of the materials DPI Tooth Moulding Powder, Protemp 4, and Revotek LC with a dimension of 10-mm diameter and 4-mm height. Similarly for flexural strength, 30 rectangular samples with a dimension of 25mm × 2mm × 2mm were made for each material. All the disc-shaped samples were dipped in bleaching agent and ΔE values were recorded before bleaching after 7 and 14 days of bleaching using spectrophotometer. For flexural strength, 10 rectangular samples of each material were kept in bleaching agent for 7 days and 10 samples were kept for 14 days. Remaining 10 without bleaching acted a control group. The data were subjected to repeated measures analysis of variance test. Result: No statistically significant difference was observed between the mean values of color change before bleaching and after 14 days of bleaching for all three materials. But statistically significant difference was observed in mean values of color change among the three materials (P 0.001). For flexural strength, statistically significant difference was observed between the mean values of flexural strength before bleaching and after 14 days of bleaching for DPI (P = 0.007) and Revotek LC (P = 0.026). Conclusion: All the three materials showed noticeable color change after 7 and 14 days of bleaching when compared with color of specimen before bleaching. Maximum color change was observed in Protemp 4 and least color change was observed in Revotek LC. Flexural strength was significantly different among the material as well as there were significant changes in flexural strength of each material after bleaching.