title: Characterization of Inorganic Filler Content, Mechanical Properties, and Light Transmission of Bulk-fill Resin Composites.
abstract: OBJECTIVE
  The aims of this study were to characterize inorganic content (IC), light transmission (LT), biaxial flexural strength (BFS), and flexural modulus (FM) of one conventional (layered) and four bulk-fill composites at different depths.
  
  
  METHODS
  Bulk-fill composites tested were Surefil SDR flow (SDR), Filtek Bulk Fill (FBF), Tetric EvoCeram Bulk Fill (TEC), and EverX Posterior (EXP). Herculite Classic (HER) was used as a control. Energy dispersive x-ray analysis and scanning electron microscopy were used to characterize filler particle composition and morphology. The LT through different composite thicknesses (1, 2, 3, and 4 mm) was measured using a laboratory-grade spectral radiometer system (n=5). For the BFS and FM tests, sets of eight stacked composite discs (0.5-mm thick) were prepared simulating bulk filling of a 4-mm-thick increment (n=8).
  
  
  RESULTS
  SDR demonstrated larger, irregular particles than those observed in TEC or HER. Filler particles in FBF were spherical, while those in EXP were composed of fiberglass strands. The LT decreased with increased composite thickness for all materials. Bulk-fill composites allowed higher LT than the HER. Furthermore, HER proved to be the unique material, having lower BFS values at deeper regions. SDR, FBF, and TEC bulk-fill composites presented reduced FM with increasing composite depth.
  
  
  CONCLUSIONS
  The bulk-fill composites investigated exhibited higher LT, independent of different filler content and characteristics. Although an increase in composite thickness reduced LT, the BFS of bulk-fill composites at deeper layers was not compromised.
authors.forename: B M
authors.initials: BM
authors.lastname: Fronza
authors.forename: Apa
authors.initials: A
authors.lastname: Ayres
authors.forename: R R
authors.initials: RR
authors.lastname: Pacheco
authors.forename: F A
authors.initials: FA
authors.lastname: Rueggeberg
authors.forename: Cts
authors.initials: C
authors.lastname: Dias
authors.forename: M
authors.initials: M
authors.lastname: Giannini
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D006244:Hardness; D008027:Light; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C000618653:EverX Posterior; C000614713:Filtek Bulk Fill; C539358:Herculite Ultra; C553871:Surefil SDR Flow; C501891:Tetric EvoCeram