Effect of uncertain quantities on the stability analysis of a miniscrew anchorage system

Abstract

PurposeTo determine how the uncertainties related to both the material properties and failure threshold value affect the failure prediction of a miniscrew using the FE analysis.Materials and MethodsThree-dimensional surface models for molar, and premolar, segments of the mandibular bone surrounding these two teeth were generated using patient-specific CT data. The 3D model was exported to a finite element Ansys/Workbench to conduct a static analysis with the traction load of 2 N exerted on the miniscrew. The probabilistic analysis was carried out to determine the failure of the miniscrew, in which Kriging was selected as the metamodeling method.ResultsThe uncertainties related to material properties significantly affect the failure probability of the miniscrew, especially for the values with a higher percentage of variability. The analyses in which a constant threshold value is considered indicate no failure, whereas the probabilistic analysis in which the random effect of the threshold value is considered yields a failure probability for the miniscrew.ConclusionTo accurately evaluate the stability of a miniscrew from an FE analysis, the computation of the failure probability of the miniscrew should take into account the uncertainty regarding the threshold value.