A method of improving marginal adaptation by elimination of singular stress point in composite restorations during resin photo-polymerization

Objectives uce the effect of stresses due to volumetric shrinkage the authors propose an incremental technique for placing composite restorations. s al of the method is to reduce the volume of the resin that is polymerized and eliminate a stress singular point in the resin that is positioned at the geometric center of the cavity. This is achieved by a two step type incremental technique. In the first step the resin is placed in the cylindrical cavity with a metal pin embedded in the middle of the composite restoration. After polymerization, the metal pin is removed and the cylindrical hole is filled with the second layer of composite. Finally, the second layer in the center of the composite restoration is polymerized. s tudy confirmed that the proposed incremental type placement technique reduces marginal debonding. icance in hypothesis is that the elimination of a stress singular point at the center of the restoration results in the reduction of stresses at tooth–composite interface and therefore improve the marginal adaptation (reduces length of the contraction gap at tooth–composite interface).