Objective: The purpose of this study was to evaluate the polymerization activity of a new photopolymerization initiator system; radical-amplified photopolymerization initiator (RAP) system.
Methods: Two types of resin composites (universal type and flowable type) using RAP technology were prepared and compared with those of the conventional photopolymerization initiator system, namely camphorquinone/ amine(CQ/amine). Polymerization activity was evaluated by means of Vickers hardness (VHN) and residual monomer amounts (RMA) with two different irradiation times (10 and 30 seconds). VHN was measured at the top surfaces of specimens (7-mm diameter and 1-mm thickness) polymerized in PTFE(Polytetrafluoroethylene) molds using halogen light (Optilux LCT), using a hardness tester (Matsuzawa seiki, MHT-1). RMA was measured by HPLC analysis of tetrahydrofuran-extracted moietis from grinded specimens (10-mm diameter and 0.5-mm thickness) polymerized in PTFE (Polytetrafluoroethylene) molds using said halogen light, using HPLC ( JASCO MD-2010-PLUS).
Results: The results of the VHN and RMA measurements are listed below.
Type of resin composite | Initiator system | VHN | RMA | ||
10 sec irradiation | 30 sec irradiation | 10 sec irradiation | 30 sec irradiation | ||
Universal | RAP | 43 | 47 | 14% | 8% |
CQ/amine | 32 | 41 | 25% | 19% | |
Flowable | RAP | 37 | 42 | 5% | 3% |
CQ/amine | 13 | 20 | 22% | 16% | |
Conclusions: RAP system showed high activity and the resin composite was cured in high degree within a short curing time using the new initiator system.