title: Influence of light intensity on contraction stress of flowable resins.
abstract: The purpose of this study was to evaluate the influence of power density on contraction stress of resin composite restorative materials during photo-polymerization. Six flowable resin composites, and a hybrid resin composite for comparison, were used. The composites were polymerized with the power density adjusted to either 100 or 600 mW/cm(2). Stress development was determined with a custom-made tensilometer. The adhesive was placed in a thin layer on a steel rod and resin paste was packed into the mold. The contraction force (N) generated during polymerization was continuously recorded and the maximum contraction stress (MPa) was calculated. Data were analyzed statistically. When the power density was adjusted to 100 mW/cm(2), the average contraction stress ranged from 0.30 to 0.50 MPa for the flowable composites, compared with 0.35 MPa for the hybrid composite. When the power density was adjusted to 600 mW/cm(2), the average contraction stress ranged from 0.34 to 1.00 MPa for the flowable composites and 0.69 MPa for the hybrid composite comparison. For all materials tested except Estelite Flow Quick, contraction stress increased with higher power density. The present results indicate that contraction stress during polymerization is influenced by power density and resin composite type.
authors.affiliation: Department of Operative Dentistry, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Takamizawa
authors.forename: Akira
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Inoue
authors.forename: Akimasa
authors.initials: A
authors.lastname: Tsujimoto
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Oto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Irokawa
authors.forename: Keishi
authors.initials: K
authors.lastname: Tsubota
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects*; D005898:Glass / Q000737:chemistry; D006801:Humans; D008027:Light; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D011109:Polymethacrylic Acids / Q000737:chemistry; D011829:Radiation Dosage; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014783:Viscosity
chemical_list: D000180:Acrylic Resins; C470433:Beautifil composite resin; C501417:Clearfil Flow FX; D003188:Composite Resins; D003764:Dental Materials; C467913:Filtek Flow; C083468:Lite-fil CR; D011108:Polymers; D011109:Polymethacrylic Acids; C501418:Unifil LoFlo Plus; C527485:estelite flow quick; C015897:glass ionomer; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide