Light induced polymerization of resin composite restorative materials

Dimensional stability of polymer-based dental materials is compromised by polymerization reaction of the monomer. The conversion into a polymer is accompanied by a closer packing of molecules, which leads to volume reduction called curing contraction or polymerization shrinkage. Curing contraction may break the adhesion between the adhesive system and hard tooth tissues forming microgaps which may result in marginal deterioration, recurrent caries and pulp injury. POLYMERIZATION SHRINKAGE OF RESIN-BASED RESTORATIVE DENTAL MATERIALS: Polymerization of the organic phase (nonomer molecules) of resin-based dental materials causes shrinkage. The space occupied by filler particles is not associated with polymerization shrinkage. However, high filler loading within certain limits, can contribute to a lesser curing contraction.