title: Light-attenuating effect of dentin on the polymerization of light-activated restorative resins.
abstract: The light-attenuating effect of dentin on the mechanical properties of light-activated composite resins was evaluated using a simple experimental filter. The filter was designed to simulate the light transmittance and light diffusion characteristics of 1.0-mm thick dentin. The depth of cure, surface hardness, and flexural strength for 13 shades of three light-activated restorative resins were examined. These resins were cured either using direct irradiation with a light source, or indirect irradiation through the filter. The attenuation of light intensity by 1.0-mm thick dentin reached 85-90% in the 400-550 nm wavelength region. For all materials, the values of depth of cure, surface hardness on the top and bottom surfaces, and flexural strength of specimens irradiated indirectly through the simulated 1.0-mm thick dentin filter decreased by 37-60%, 16-55%, 50-83%, and 44-82% in comparison with those by direct irradiation, respectively. Recovery from mechanical properties' reduction was achieved when materials were irradiated 1.5-4 times longer than the standard irradiation time.
authors.affiliation: Department of Biomaterials Science, Field of Oral and Maxillofacial Rehabilitation, Developmental Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan. hiro@dentb.hal.kagoshima-u.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Arikawa
authors.forename: Takahito
authors.initials: T
authors.lastname: Kanie
authors.forename: Koichi
authors.initials: K
authors.lastname: Fujii
authors.forename: Seiji
authors.initials: S
authors.lastname: Ban
authors.forename: Hideo
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D003116:Color; D003188:Composite Resins / Q000528:radiation effects*; D003804:Dentin / Q000737:chemistry*; D004058:Diffusion; D004548:Elasticity / Q000528:radiation effects; D005374:Filtration / Q000295:instrumentation; D006244:Hardness / Q000528:radiation effects; D006801:Humans; D008027:Light; D008422:Materials Testing; D044367:Phase Transition / Q000528:radiation effects; D018583:Pliability / Q000528:radiation effects; D012542:Scattering, Radiation
chemical_list: D003188:Composite Resins; C083468:Lite-fil CR; C086113:palfique estelite; C074741:Silux Plus