[The microstructure and materials properties of provisional crown and bridge materials].

The fracture resistance, surface hardness and microstructure of different manually and automatically mixed temporary crown and bridge resins and two light cured materials were examined in this study. The materials on butylmethacrylate (BMA) based showed low transverse strength compared to the materials on urethanmethacrylate (UDMA) and Bis-GMA base. Their values corresponded to the transverse strength of a manually mixed, chemically cured resin on PMMA base. The automatically mixed material on Bis-GMA base had lower strength values and surface hardness but fewer macroporosities compared to the manually mixed resins. The light cured material on UDMA base showed a transverse strength and surface hardness, which were higher than the values of the materials on Bis-GMA base. The strength values of the light cured material on PMMA base decreased within 7 days and were already after 24 h in the range of the materials on BMA base.