title: Influence of adding nanoparticles on the hardness, tear strength, and permanent deformation of facial silicone subjected to accelerated aging.
abstract: BACKGROUND
  The efficiency of adding nanoparticles to silicone protection has proven to prevent color degradation. However, reports of other physical property changes in facial silicone are scarce.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the influence of adding nanoparticles on the hardness, tear strength, and permanent deformation of a facial silicone.
  
  
  METHODS
  Specimens were made for each test, with 140 for the hardness test, 140 for the permanent deformation test, but 280 for the rupture test. This higher number was due to the fact that the first 140 specimens were ruptured and unusable after the initial reading. ZnO, BaSO4, and TiO2nanoparticles at concentrations of 1% and 2% of silicone were used, as well as specimens without nanoparticles that consisted of only oil paint and of only silicone. Outcomes were measured before and after 1008 hours of accelerated aging. Data were analyzed by nested analysis of variance (ANOVA) and Tukey honest significant differences test (α=.05).
  
  
  RESULTS
  Results showed that the presence of nanoparticles influenced the properties of the assessed groups. The nanoparticles decreased hardness values. The highest values of tear strength were observed for the groups with addition of BaSO4. The 1% ZnO group without oil paint showed the lowest values of permanent deformation.
  
  
  CONCLUSIONS
  Based on the findings of this in vitro study, the use of ZnO nanoparticles is recommended, since they did not negatively affect the properties of the materials evaluated.
authors.affiliation: Doctoral student, Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Sao Paulo State University, Sao Paulo, Brazil.
authors.forename: Adhara S
authors.initials: AS
authors.lastname: Nobrega
authors.affiliation: Doctoral student, Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Sao Paulo State University, Sao Paulo, Brazil.
authors.forename: Agda M
authors.initials: AM
authors.lastname: Andreotti
authors.affiliation: Adjunct Professor, Department of Oral Surgery, Pathology and Dental Clinical, School of Dentistry, Minas Gerais Federal University, Minas Gerais, Brazil.
authors.forename: Amália
authors.initials: A
authors.lastname: Moreno
authors.affiliation: Professor, Department of Prosthodontics and Periodontics, Piracicaba Dental School, Campinas University, Sao Paulo, Brazil.
authors.forename: Mário A C
authors.initials: MA
authors.lastname: Sinhoreti
authors.affiliation: Professor, Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Sao Paulo State University, Sao Paulo, Brazil.
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Dos Santos
authors.affiliation: Professor, Department of Dental Materials and Prosthodontics, Aracatuba Dental School, Sao Paulo State University, Sao Paulo, Brazil. Electronic address: goiato@foa.unesp.br.
authors.forename: Marcelo C
authors.initials: MC
authors.lastname: Goiato
mesh_terms: D019544:Equipment Failure Analysis; D006244:Hardness; D006801:Humans; D008447:Maxillofacial Prosthesis / Q000592:standards; D064347:Microscopy, Electrochemical, Scanning; D053758:Nanoparticles; D011475:Prosthesis Failure; D013718:Tensile Strength; D015034:Zinc Oxide / Q000627:therapeutic use
chemical_list: D015034:Zinc Oxide