Influence of Polymerization Light Intensity on the Polymerization Shrinkage of Composite Materials (Part III)

Despite daily perfecting both the composite material and light sources, the polymerization shrinkage of composite materials still remains a significant problem that compromises longevity of composite fillings. On average, the composite materials shrink 1-5% volume (1). Total shrinkage can be divided into preand postgelation phase. During the pregelation phase, the composite material is not completely set and monomers have the possibility of rearrangement within the forming polymer matrix. During the post-gelation phase monomers loose that ability, which results in the occurrence of stress on surrounding cavity walls and on the bond between the tooth and composite material (2). As a consequence of stress, defects can form inside the bond between the tooth structure and the composite material, breakage and formation of microcracks that further causes postoperative sensitivity and recurrent caries. There are several ways of compensating the negative effect of polymerization shrinkage, including placement of liner, layered placement of composInfluence of Polymerization Light Intensity on the Polymerization Shrinkage of Composite Materials (Part III) Alena Knežević1 Nazif Demoli2 Zrinka Tarle1 Višnja Negovetić Mandić1