Microhardness of provisional fixed prosthodontic materials

Statement of problem. Provisional restorations play a critical role in the success of restorative treatment. Thus, the provisional restoration must ma intain its surface integrity throughout the restorative process. Purpose. This study evaluated the microhardness of 5 prosthodontic provisio nal materials. Material and methods. Cylindrical samples of 3 bis-acryl resin composites ( Integrity, Protemp Garant, Temphase) and 2 methyl methacrylate acrylic resi ns (Tet, Temporary Bridge) were fabricated (n = 5 per material). Specimens were wet sanded through 600 grit abrasive and stored in artificial saliva a t 37 degrees C for a total of 14 days. Baseline Knoop hardness (KHN) was me asured 24 hours after specimen fabrication. Three microhardness measurement s were obtained from each specimen. Knoop hardness ass again recorded after 14 days of storage. Results. ANOVA and Duncan's tests (P<.05) indicated a significant differenc e between the methyl methacrylate: type resins and the bis-acryl resin comp osites at both time intervals. Conclusion. The hardness of most materials (Integrity, Protemp Garant, Tet) decreased over time. All of the bis-acryl resin composite materials exhibi ted superior microhardness over traditional methyl methacrylate (Tet, Tempo rary Bridge) resins.