title: Addition of a Fluoride-containing Radiopacifier Improves Micromechanical and Biological Characteristics of Modified Calcium Silicate Cements.
abstract: BACKGROUND
  Calcium silicate cements (CSCs) with the addition of nanohydroxyapatite and calcium carbonate play a critical role in dental applications. To further improve their properties, particularly radiopacity and biointeractivity, the fluoride-containing radiopacifier ytterbium trifluoride (YbF3) was added to their composition, and biological and mechanical characteristics were evaluated.
  
  
  METHODS
  YbF3 was added to 3 different CSCs: cement I (CSC + calcium carbonate), cement II (CSC + nanohydroxyapatite), and Portland cement. Material characterization encompassed measurements of pH, calcium, ytterbium, and fluoride ion release; radiopacity; setting time; porosity; microindentation properties; wettability; and Fourier transform infrared spectroscopic, x-ray diffraction, and scanning electron microscopic analyses. Osteoblast- and osteoclast-like cells were grown on the materials' surface to evaluate their adherence.
  
  
  RESULTS
  The addition of calcium carbonate, nanohydroxyapatite, and 30 wt% of YbF3 improved radiopacity and the setting time of experimental cements. The pH values did not differ among the groups. The greatest ytterbium and fluoride releases occurred in the Portland cement + YbF3 group. Combined x-ray diffraction and Fourier transform infrared spectroscopic analysis showed the presence of calcium hydroxide and calcium silicate hydrates. In addition, the presence of calcium ytterbium fluoride and ytterbium oxide proved that YbF3 reacted with cement compounds. Wettability of cement I + YbF3 was superior to other formulations, but its porosity and microindentation properties were weaker than in the Portland cement + YbF3 mixture. Cement II + YbF3 presented micromechanical indentation and porosity characteristics similar to the Portland-based cement formulation. Osteoclast- and osteoblast-like cells adhered to the cements' surfaces without alteration of the cell structural integrity.
  
  
  CONCLUSIONS
  YbF3-containing CSCs with nanostructured hydroxyapatite and calcium carbonate are well suited for dental application.
authors.affiliation: Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Djordje
authors.initials: D
authors.lastname: Antonijevic
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Jeschke
authors.affiliation: Laboratory for Atomic Physics, Institute for Nuclear Sciences "Vinca", University of Belgrade, Belgrade, Serbia.
authors.forename: Bozana
authors.initials: B
authors.lastname: Colovic
authors.affiliation: Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Petar
authors.initials: P
authors.lastname: Milovanovic
authors.affiliation: Department for Prosthodontics, Dental School Pančevo, University of Business Academy, Novi Sad, Serbia.
authors.forename: Danimir
authors.initials: D
authors.lastname: Jevremovic
authors.affiliation: Laboratory for Atomic Physics, Institute for Nuclear Sciences "Vinca", University of Belgrade, Belgrade, Serbia.
authors.forename: Danilo
authors.initials: D
authors.lastname: Kisic
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: vom Scheidt
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hahn
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Amling
authors.affiliation: Laboratory for Atomic Physics, Institute for Nuclear Sciences "Vinca", University of Belgrade, Belgrade, Serbia.
authors.forename: Vukoman
authors.initials: V
authors.lastname: Jokanovic
authors.affiliation: Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Busse
authors.affiliation: Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, Belgrade, Serbia. Electronic address: marijadjuric5@gmail.com.
authors.forename: Marija
authors.initials: M
authors.lastname: Djuric
mesh_terms: D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002448:Cell Adhesion; D003738:Dental Cements / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites / Q000737:chemistry*; D051379:Mice; D053758:Nanoparticles / Q000737:chemistry; D010006:Osteoblasts / Q000166:cytology; D016062:Porosity; D017640:Silicates / Q000737:chemistry*; D017155:Wettability; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D003738:Dental Cements; D006882:Hydroxyapatites; D017640:Silicates; C475044:hydroxyapatite cement; C102799:ytterbium fluoride; D002119:Calcium Carbonate; D015018:Ytterbium; D005459:Fluorides; C031293:calcium silicate
keywords: Bioactivity; calcium silicate; dental cement; fluoride; micro–computed tomography; osteoblasts; reference point indentation