Polymerization shrinkage of composite resins using plasma-arc photocuring.

When composite resins are photocured, they undergo a certain degree of polymerization shrinkage. A new method utilizes plasma-arc photocuring instead of conventional visible light. The purpose of this in vitro investigation was to compare the amount of linear shrinkage that occurs when a hybrid composite resin is cured using three different plasma-arc light (PAL) sources. There was no significant difference between the three groups and a halogen light control in the amount of shrinkage of the hybrid composite resin. In terms of resin shrinkage values, using a PAL is no different than using a conventional halogen curing light. However, even though the curing intensity is increased, the shorter curing times may result in a reduced depth of cure.