Effect of Framework Type on the Biomechanical Behavior of Provisional Crowns: Strain Gauge and Finite Element Analyses.

The aim of this study was to evaluate the effects of different frameworks on the biomechanical behavior of implant-supported provisional single crowns to indicate or not the use of plastic framework as infrastructure. For finite element analysis, a hemi-jaw stone model was scanned and modeled with an external hexagon implant. A framework was screwed onto the implant and a crown was constructed over it. The set was made in triplicate according to framework type: plastic, cobalt-chromium (CoCr), and titanium. Models were exported in volumetric format to analysis software where structures were considered isotropic, linear, elastic, and homogeneous. Axial loads (100, 200, and 300 N) were applied to the fossa bottom, and the system's fixation occurred on the bone base. For strain-gauge analysis, the same hemi-jaw model was built in polyurethane and an implant was placed on it. Three crowns were made, each one with a different framework. Four strain gauges were glued around the implant to obtain microstrain values. The data were analyzed by three-way analysis of variance (ANOVA) and Tukey tests (P < .05). Finite element analysis exhibited microstrain results for bone, von Mises stress values for the implant and screw, and maximum principal stress values for the crown. For computational method, as the applied load increased, so did the stress generated. Titanium frameworks concentrated more stress in the crown and bone, while plastic ones concentrated more in the implant and screw. ANOVA showed that the higher the load value and the framework elastic modulus, the higher the generated microstrain in bone. It can be concluded that all evaluated framework types can be used in the manufacturing of provisional crowns.