title: In vitro study of the antibacterial properties and impact strength of dental acrylic resins modified with a nanomaterial.
abstract: BACKGROUND
  The accumulation of bacteria on the surface of dental prostheses can lead to systemic disease.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the growth of Staphylococcus aureus and Pseudomonas aeruginosa on the surface of autopolymerizing (AP) and heat-polymerizing (HP) acrylic resins incorporated with nanostructured silver vanadate (β-AgVO3) and its impact strength.
  
  
  METHODS
  For each resin, 216 circular specimens (9 × 2 mm) were prepared for microbiologic analysis and 60 rectangular specimens (65 × 10 × 3.3 mm) for mechanical analysis, according to the percentage of β-AgVO3: 0%, control group; 0.5%; 1%; 2.5%; 5%; and 10%. After a biofilm had formed, the metabolic activity of the bacteria was measured using the XTT reduction assay (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) (n=8), and the number of viable cells was determined by counting colony forming units per milliliter (CFU/mL) (n=8). Confocal laser scanning microscopy (CLSM) was used to complement the analyses (n=2). The mechanical behavior was evaluated by impact strength assays (n=10). Data were analyzed by 2-way ANOVA, followed by the Tukey honestly significant difference (HSD) post hoc test (α=.05).
  
  
  RESULTS
  The addition of 5% and 10% β-AgVO3 significantly decreased the metabolic activity of P. aeruginosa for both resins (P<.05). The HP resin promoted a greater reduction in metabolic activity than the AP resin (P<.05). No difference was found in the metabolic activity of S. aureus according to the XTT (P>.05). The number of CFU/mL for S. aureus and P. aeruginosa decreased significantly when 5% and 10% β-AgVO3 were added (P<.001). These concentrations significantly reduced the impact strength of the resins (P<.001) because the system was weakened by the presence of clusters of β-AgVO3.
  
  
  CONCLUSIONS
  The addition of β-AgVO3 can provide acrylic resins with antibacterial activity but reduces their impact strength. More efficient addition methods should be investigated.
authors.affiliation: Doctoral student, Department of Dental Materials and Prosthodontics, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Denise T
authors.initials: DT
authors.lastname: de Castro
authors.affiliation: Doctoral student, Department of Dental Materials and Prosthodontics, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Mariana L C
authors.initials: ML
authors.lastname: Valente
authors.affiliation: Associate Professor, Department of Materials Engineering, Federal University of São Carlos (UFSCAR), São Carlos, Brazil.
authors.forename: José Augusto M
authors.initials: JA
authors.lastname: Agnelli
authors.affiliation: Associate Professor, Department of Dental Materials and Prosthodontics, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Cláudia H
authors.initials: CH
authors.lastname: Lovato da Silva
authors.affiliation: Professor, Department of Restorative Dentistry, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Evandro
authors.initials: E
authors.lastname: Watanabe
authors.affiliation: Doctoral student, Department of Materials Engineering, Federal University of São Carlos (UFSCAR), São Carlos, Brazil.
authors.forename: Renato L
authors.initials: RL
authors.lastname: Siqueira
authors.affiliation: Professor, Laboratory of Solid State Chemistry, State University of Campinas (UNICAMP), Campinas, Brazil.
authors.forename: Oswaldo L
authors.initials: OL
authors.lastname: Alves
authors.affiliation: Private practice, Campinas, Brazil.
authors.forename: Raphael D
authors.initials: RD
authors.lastname: Holtz
authors.affiliation: Associate Professor, Department of Dental Materials and Prosthodontics, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, Brazil. Electronic address: andreare@forp.usp.br.
authors.forename: Andréa C
authors.initials: AC
authors.lastname: dos Reis
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D003819:Denture Bases; D008422:Materials Testing; D053761:Nanocomposites / Q000737:chemistry*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D012117:Resins, Synthetic / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; D000900:Anti-Bacterial Agents; D012117:Resins, Synthetic