title: The addition of silica nanoparticles on the mechanical properties of dental stone.
abstract: BACKGROUND
  The current application of nanotechnology in dentistry is limited to nanoparticles incorporated into adhesive systems and composite resins. Dental stone is a widely used material, and the incorporation of silica nanoparticles is still unexplored.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the mechanical properties of dental stone after the addition of silica nanoparticles in different concentrations.
  
  
  METHODS
  A total of 180 specimens were prepared, 90 for each dental stone (Durone and Fuji Rock). For the control group (CG), no silica particles were added, while test group TGnI had silica nanoparticles added to 1 wt%, and test group TGnV had silica nanoparticles added to 5 wt%. The roughness, diametral tensile strength (DTS), and compressive strength were measured 24 hours after the start of spatulation.
  
  
  RESULTS
  The mean roughness values for Durone were 0.55, 0.36, and 0.28 μm for CG, TGnI, and TGnV; for Fuji Rock, the mean roughness values were 0.47 for CG, 0.31 for TGnI, and 0.35 μm for TGnV. The mean DTS values for Durone were 6.0, 5.1, and 5.0 MPa for CG, TGnI, and TGnV, respectively, and for Fuji Rock, the mean DTS values were 6.4, 5.2, and 4.5 MPa for CG, TGnI, and TGnV, respectively. The mean compressive strength values for Durone were 35.4, 32.7, and 32.4 MPa for CG, TGnI, and TGnV, respectively, and for Fuji Rock, the mean compressive strength values were 42.9, 31.2, and 29.8 MPa for CG, TGnI, and TGnV respectively.
  
  
  CONCLUSIONS
  Surface roughness was statistically lower for the Durone and Fuji Rock stones (P<.001) when silica nanoparticles were added. The addition of silica nanoparticles did not significantly affect the DTS and compressive strength of Durone compared with CG (P>.05) but did affect the DTS of Fuji Rock when 5 wt% was added and the compressive strength in both concentrations (P<.05).
authors.affiliation: Postgraduate student, Postgraduate in Dental Materials, Department of Restorative Dentistry, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil. Electronic address: leonardo@leonardodecesero.com.br.
authors.forename: Leonardo
authors.initials: L
authors.lastname: De Cesero
authors.affiliation: Postgraduate student, Department of Physical, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
authors.forename: Elisa Magno Nunes
authors.initials: EMN
authors.lastname: de Oliveira
authors.affiliation: Professor, Department of Restorative Dentistry, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
authors.forename: Luiz Henrique
authors.initials: LH
authors.lastname: Burnett Junior
authors.affiliation: Coordinator, Interdisciplinary Center of Nanoscience and Micro-Nanotechnology, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
authors.forename: Ricardo Meurer
authors.initials: RM
authors.lastname: Papaléo
authors.affiliation: Professor, Department of Restorative Dentistry, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
authors.forename: Eduardo Gonçalves
authors.initials: EG
authors.lastname: Mota
mesh_terms: D002133:Calcium Sulfate; D019245:Compressive Strength; D003764:Dental Materials; D008422:Materials Testing; D053758:Nanoparticles; D012822:Silicon Dioxide; D013718:Tensile Strength
chemical_list: D003764:Dental Materials; D012822:Silicon Dioxide; D002133:Calcium Sulfate