Experimental validation of a finite element model of light-activated polymerization shrinkage

An important consideration in improving the longevity of dental resin composite restorations is how to minimize the stresses that develop between resin composites and the wall of the preparation as the resin shrinks during polymerization. If the stress is too great, failure of the bonded interface occurs and microleakage results, with possible margin failure, staining, and secondary caries. This present project was performed to validate a previously developed FEM approach for investigating polymerization shrinkage. Light-cured resin composite was condensed into a cylindrical cavity preparation, which contained a centrally located wire. A profilometer stylus was positioned on the end of the wire to detect the initial surface displacement as the wire moved with the superficial layer of composite resin. The plots of the experimentally derived data were compared to the data plot from the FEM. The initial segments of the experimental plots matched the calculated plot very closely in shape, thus validating the FEM approach.