Premolar cuspal deflection following operative procedures: 3D-FEA using micro-CT data

Objectives: The aim of this investigation is to use a premolar micro CT data, stereolithography and surface-driven automatic meshing to generate finite element models of different restorative conditions and attempt to validate the numeric data by comparison to existing experimental data.Methods: An intact maxillary premolar was digitized with a micro-CT scanner. Using an interactive medical image control system, surface contours of enamel and dentin were fitted following tooth segmentation based on pixel density. The remeshed stereolithography (STL) files of enamel and dentin surfaces were then imported in a rapid prototyping software. Interfacial mesh congruence (dentinoenamel junction) was assured by Boolean operations, also used to generate different cavity preparations (MO/MOD preparations) and corresponding composite resin restorations. 3D solid models were created by importing the enamel/dentin/restoration parts in a finite element software package. Occlusal loading was simulated using nonlinear contact analysis. Cuspal deflection was measured at different restorative steps and correlated with existing experimental data for model validation. Results: Existing experimental data allowed the validation of five different models. Cuspal widening (between buccal and lingual cusp tips) at 150N load ranged from 2.6 microns for the unrestored tooth to 10—31 microns for MO, MOD cavities. MO, MOD adhesive restorations in composite resin subjected to 150N resulted in significant recovery of cuspal stiffness, with 3.5 microns and 3.9 microns of cuspal widening, respectively.Conclusions: Three dimensional finite element models of a premolar tooth with different cavities and restorative materials were generated with a rapid and valid method.