Finite Element Stress Analysis of Composite Polymerisation Shrinkage in Endodontically Treated Maxillary Central Incisors

Introduction : Resin composites are common materials used to restore anterior teeth following root canal therapy, but are accompanied with shrinkage during polymerization. The aim of this in vitro study was to investigate the effect of the insertion method and polymerization shrinkage of resin composite on residual tooth structure. Materials and Methods : Stereomicroscopy and computerized Finite Element Modelling (FEM) were used to compare residual stresses in endodontically treated, extracted maxillary central incisor teeth, in which the access cavities were restored with resin composite. Theoretical stresses derived from the FEM were analyzed during preparation and after teeth were restored using either a “bulk” or a “wedge incremental” method. These data were subsequently compared with stresses measured directly using strain gauges. Results : Results showed that intensive stresses, which had the potential to cause fracture in dental structures and composite de-bonding, were applied to teeth during polymerization. Conclusion : According to the results of this study, the “bulk” build up led to less stress induction during restoration of teeth following root canal therapy. Key words : Finite Element, Polymerization, Resin Composite