title: Influence of light activation on the volumetric change of core foundation resins.
abstract: A core foundation system is frequently used in endodontically treated teeth that suffer excessive loss of the coronal portion of their structure. The volumetric shrinkage of core foundation resins may create marginal gaps that influence the bonding ability and longevity of a restored tooth. Little is known about how activation conditions of resin core foundation resin pastes affect their volumetric shrinkage. This study evaluated the influence of light intensity and light activation duration on volumetric shrinkage of direct core foundation resins. Two dual- and one light-activated core foundation resin pastes were employed. The material was placed in a Teflon mold 4 mm in diameter and 2 mm in height and extruded into a water filled dilatometer. The specimens were then light activated and the change in height of the meniscus of water was recorded using a charged-coupled device camera. The average volumetric shrinkage of the core foundation resins after 180 seconds ranged from 1.53% to 2.63%. For all materials tested, there was a tendency for increased volumetric shrinkage with increased light activation time and intensity. The results of this study indicate that the volumetric change of core foundation resins is influenced by the time and intensity of light activation.
authors.affiliation: Department of Operative Dentistry, Nihon University Graduate School of Dentistry, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Uekusa
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Akitomo
authors.initials: A
authors.lastname: Rikuta
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kurokawa
authors.forename: B Keith
authors.initials: BK
authors.lastname: Moore
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000528:radiation effects*; D018772:Dental Marginal Adaptation; D003799:Dental Stress Analysis; D008027:Light; D008422:Materials Testing; D044367:Phase Transition; D011176:Post and Core Technique; D011874:Radiometry; D019279:Resin Cements / Q000528:radiation effects; D018709:Statistics, Nonparametric
chemical_list: C469237:Clearfil Core; D003188:Composite Resins; D019279:Resin Cements; C500741:Unifil Core