title: How filler properties, filler fraction, sample thickness and light source affect light attenuation in particulate filled resin composites.
abstract: OBJECTIVE
  It was hypothesized that by standardizing variables such as light sources, filler types and filler surface treatment, it should be possible to use Beer-Lambert's law to predict light absorption in visible light-cured dental composites.
  
  
  METHODS
  Mixture of 50 wt% bisGMA and 50 wt% TEGDMA to which a photo-initiator (0.35 wt% champhorquinone) and a co-initiator (0.7 wt% of dimethylaminoethylmethacrylate) was prepared. Three different filler types (HBB, SBB and KU) were added to that mixture in eight different volume percentage. Filler particles were either silane surface treated or not. Specimens were made with thicknesses of 1-5 mm. Total number of 1200 specimens were made for this study. Light transmission was obtained for halogen source and laser lights, which made the number of observations 2400. The absorbance values of the different materials were analyzed in Matlab with respect to the differences in filler fraction and sample thickness.
  
  
  RESULTS
  The obtained results revealed that of the two light sources, more light was absorbed by the composite when the laser light was used. Among different filler types, the HBB filler absorbed most light and the KU filler the least. There were significant differences (p < 0.05) in light absorption between all three filler types.
  
  
  CONCLUSIONS
  By comparing the modeled surfaces generated by Matlab for different materials it was possible to determine how different variables such as filler type, filler surface treatment and light source affect light attenuation. The characteristic of incident light affected the light absorbance, meaning that not only the composite's composition needs to be considered in light absorption studies of dental composites.
authors.affiliation: Division of Polymer Engineering, Luleå University of Technology, SE-971 87 Luleå, Sweden. nazanin.emami@sirius.luth.se
authors.forename: Nazanin
authors.initials: N
authors.lastname: Emami
authors.forename: Mikael
authors.initials: M
authors.lastname: Sjödahl
authors.forename: Karl-Johan M
authors.initials: KJ
authors.lastname: Söderholm
mesh_terms: D000042:Absorption; D017609:Barium Compounds / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D005544:Forecasting; D006801:Humans; D007834:Lasers; D008027:Light; D008029:Lighting / Q000295:instrumentation; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D055095:Optics and Photonics; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D012031:Refractometry; D012821:Silanes / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D013499:Surface Properties; D013729:Terpenes / Q000737:chemistry
chemical_list: D017609:Barium Compounds; D003188:Composite Resins; D008689:Methacrylates; D011109:Polymethacrylic Acids; D012821:Silanes; D017640:Silicates; D013729:Terpenes; C415406:barium borosilicate; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C048339:camphoroquinone; C049840:2-(dimethylamino)ethyl methacrylate