title: Effect of irradiation mode on polymerization of dental composite resins.
abstract: Many researchers have sought to reduce the polymerization shrinkage in composite resins. Controlling the irradiation light seems practical because the polymerization process initiates with light by activating the photoinitiators. The present study evaluated the effect of irradiation mode on microhardness and polymerization shrinkage of composite resins. Three different irradiation modes, STD, EXP, and MED, were taken under 40-s exposure condition. As results, the irradiation mode significantly affected the microhardness difference. However, in all products, the microhardness difference between the STD and MED modes was less than 10%. In all irradiation modes, microhardness was linearly correlated with the filler content of the tested specimens. The effect of mode on the difference of the polymerization shrinkage was not uniform even though the shrinkage values decreased following the order of the STD > EXP > MED mode. An inverse correlation was found between filler content and polymerization shrinkage in all irradiation modes and specimen thicknesses. In spite of the statistical significance of the irradiation modes on the difference of the measured values, their numeric difference was not great. Especially, compared with the STD and MED mode, the exponentially increasing light (EXP mode) produced no noticeable difference except for a delayed shrinkage process.
authors.affiliation: Department of Dental Materials, College of Dentistry and Medical Research Ihhnstitute, Pusan National University, Pusan 602-739, Republic of Korea.
authors.forename: Yong Hoon
authors.initials: YH
authors.lastname: Kwon
authors.forename: Soon-Il
authors.initials: SI
authors.lastname: Kang
authors.forename: Bock
authors.initials: B
authors.lastname: Hur
authors.forename: Jeong Kil
authors.initials: JK
authors.lastname: Park
authors.forename: Hyung-Il
authors.initials: HI
authors.lastname: Kim
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D004307:Dose-Response Relationship, Radiation; D008027:Light; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods
chemical_list: D003188:Composite Resins