title: Reinforcement of a PMMA resin for interim fixed prostheses with silica nanoparticles.
abstract: Fractures in long span provisional/interim restorations are a common complication. Adequate fracture toughness is necessary to resist occlusal forces and crack propagation, so these restorations should be constructed with materials of improved mechanical properties. The aim of this study was to investigate the possible reinforcement of neat silica nanoparticles and trietoxyvinylsilane-modified silica nanoparticles in a PMMA resin for fixed interim restorations.
  
  
  
  Composite PMMA-Silica nanoparticles powders were mixed with PMMA liquid and compact bar shaped specimens were fabricated according to the British standard BS EN ISO 127337:2005. The single-edge notched method was used to evaluate fracture toughness (three-point bending test), while the dynamic thermomechanical properties (Storage Modulus, Loss Modulus, tanδ) of a series of nanocomposites with different amounts of nanoparticles (0.25%, 0.50%, 0.75%, 1% w.t.) were evaluated. Statistical analysis was performed and the statistically significant level was set to p<0.05.
  
  
  
  The fracture toughness of all experimental composites was remarkably higher compared to control. There was a tendency to decrease of fracture toughness, by increasing the concentration of the filler. No statistically significant differences were detected among the modified/unmodified silica nanoparticles. Dynamic mechanical properties were also affected. By increasing the silica nanoparticles content an increase in Storage Modulus was recorded, while Glass Transition Temperature was shifted at higher temperatures.
  
  
  
  Under the limitations of this in-vitro study, it can be suggested that both neat silica nanoparticles and trietoxyvinylsilane-modified silica nanoparticles, especially at low concentrations, may enhance the overall performance of fixed interim prostheses, as can effectively increase the fracture toughness, the elastic modulus and the Glass Transition Temperature of PMMA resins used in fixed provisional restorations.
authors.affiliation: School of Health Sciences, Department of Dentistry, Section of Prosthodontics, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
authors.forename: Marianthi
authors.initials: M
authors.lastname: Topouzi
authors.affiliation: School of Health Sciences, Department of Dentistry, Section of Prosthodontics, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
authors.forename: Eleana
authors.initials: E
authors.lastname: Kontonasaki
authors.affiliation: Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Bikiaris
authors.affiliation: Department of Geology, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
authors.forename: Lambrini
authors.initials: L
authors.lastname: Papadopoulou
authors.affiliation: Department of Physics, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.
authors.forename: Konstantinos M
authors.initials: KM
authors.lastname: Paraskevopoulos
authors.affiliation: School of Health Sciences, Department of Dentistry, Section of Prosthodontics, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece. Electronic address: pkoidis@dent.auth.gr.
authors.forename: Petros
authors.initials: P
authors.lastname: Koidis
mesh_terms: D003188:Composite Resins; D003794:Dental Restoration, Temporary; D003799:Dental Stress Analysis; D008422:Materials Testing; D053758:Nanoparticles; D018583:Pliability; D019904:Polymethyl Methacrylate; D019736:Prostheses and Implants; D012822:Silicon Dioxide; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D012822:Silicon Dioxide; D019904:Polymethyl Methacrylate
keywords: Dental fixed interim prostheses; Fracture toughness; Nanonocomposites; Poly(methyl methacrylate)-PMMA; Silica nanoparticles; Viscoelastic properties