title: Effects of various light curing methods on the leachability of uncured substances and hardness of a composite resin.
abstract: The purpose of this study was to evaluate the effect of the various light curing units (plasma arc, halogen and light-emitting diodes) and irradiation methods (one-step, two-step and pulse) using different light energy densities on the leachability of unreacted monomers (Bis-GMA and UDMA) and the surface hardness of a composite resin (Z250, 3M). Leachability of the specimens immersed for 7 days in ethanol was analysed by HPLC. Vicker's hardness number (VHN) was measured immediately after curing (IC) and after immersion in ethanol for 7 days. Various irradiation methods with three curing units resulted in differences in the amount of leached monomers and VHN of IC when light energy density was lower than 17.0 J cm(-2) (P = 0.05). However, regardless of curing units and irradiation methods, these results were not different when the time or light energy density increased. When similar light energy density was irradiated (15.6-17.7 J cm(-2)), the efficiency of irradiation methods was different by the following order: one-step > or = two-step > pulse. These results suggest that the amount of leached monomers and VHN were influenced by forming polymer structure in activation and initiation stages of polymerization process with different light source energies and curing times.
authors.affiliation: College of Dentistry, Seoul National University, Seoul, Korea.
authors.forename: H-J
authors.initials: HJ
authors.lastname: Moon
authors.forename: Y-K
authors.initials: YK
authors.lastname: Lee
authors.forename: B-S
authors.initials: BS
authors.lastname: Lim
authors.forename: C-W
authors.initials: CW
authors.lastname: Kim
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000528:radiation effects; D003188:Composite Resins / Q000528:radiation effects; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis / Q000379:methods; D017220:Dentin-Bonding Agents / Q000528:radiation effects; D006244:Hardness / Q000528:radiation effects; D006245:Hardness Tests; D006801:Humans; D008027:Light; D008689:Methacrylates / Q000528:radiation effects; D011140:Polyurethanes / Q000528:radiation effects; D019279:Resin Cements / Q000528:radiation effects; D013499:Surface Properties
chemical_list: C103506:Bis-GMA, BPDM, HEMA dental-bonding resin; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D011140:Polyurethanes; D019279:Resin Cements; C029824:urethane dimethacrylate luting resin; D017438:Bisphenol A-Glycidyl Methacrylate