Evaluation of the effect of dynamic loading on the fracture load of temporary crown and bridge materials

This study aimed to evaluate the effect of material, manufacturing type and dynamic loading on the fracture loads of three-unit fixed dental prostheses (FDPs) for temporary restorations, prepared with seven different materials using either computer-aided design/computer-aided manufacturing (CAD/CAM) or conventional methods. FDPs were fabricated (N=168) from CAD/CAM resins; CAD/CAM Unfilled polymethylmethacrylate (CCUP), CAD/CAM Filled Poliacrylate (CCFP) and conventionally fabricated resins; self cure polymethylmethacrylate (SPM), self cure polyethylmethacrylate (SPE); self cure bis-acrylate composite (SBC), dual cure bis-acrylate composite (DBC), light cure UDMA composite resin. In this study, 168 temporary bridge restorations were prepared, 24 of which are 7 temporary crown-bridge resin materials. The FDPs were divided into three equal groups, with eight specimens per material in each group. Control group: The group to which only the fracture test was applied. Experimental group I: The group to which the fracture test was applied after 5.000 TC (5oC/55oC) and 60.000 DL. Experimental group II: The group to which the fracture test was applied after 5.000 TC (5oC/55oC) and 120.000 DL. Dynamic loading parameters: 50 N of chewing load, 1.6 Hz chewing frequency, 2 mm lateral sliding. The fracture load of the specimens were measured by using a Universal test device. Data were statistically evaluated with two-way analysis of variance (Two-way ANOVA) and one-way analysis of variance (One-way ANOVA), Tukey HDS test. Significance was evaluated in p<0.05 level. The highest fracture load (798.03 N) was found in the CCUP specimen, while the lowest was found in SPM (269.54 N). After dynamic loading; the fracture loads were significantly higher in the DBC and SBC materials than the SPM, SPE and LUC materials (p <0.001). No significant difference was found in the fracture load for CCUP, CCFP, SPE and SBC (p> 0.05). However, a statistically significant decrease in the fracture load was found for SPM, DBC and LUC (p <0.05).