Effect of plasma arc curing on polymerization shrinkage of orthodontic adhesive resins

summary The purpose of this study was to evaluate the polymerization shrinkage of three orthodontic adhesive resins when polymerized with a high‐energy plasma arc light (1340 mW cm−2) and a conventional halogen light (500 mW cm−2), and to correlate the polymerization shrinkage with the degree of conversion. To equalize the total light energy delivered to the adhesive resin, irradiation time was varied between 3 or 6 s for a plasma arc‐curing unit, and 8 or 16 s for a halogen light‐curing unit. The polymerization shrinkage of adhesive resins during the light‐curing process was measured using a computer‐controlled mercury dilatometer and the degree of conversion was measured using Fourier transform infrared spectroscopy. A plasma arccuring unit produced significantly lower polymerization shrinkage than a halogen light‐curing unit when the equivalent total light energy was irradiated to the orthodontic adhesive resins (P