title: Novel dental composites reinforced with zirconia-silica ceramic nanofibers.
abstract: OBJECTIVE
  To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers.
  
  
  METHODS
  Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37°C deionized water for 24h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey's Honestly Significant Differences test used for post hoc analysis.
  
  
  RESULTS
  Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content.
  
  
  CONCLUSIONS
  Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life.
authors.affiliation: Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Sciences Center, School of Dentistry, New Orleans, LA 70119, USA.
authors.forename: Guangqing
authors.initials: G
authors.lastname: Guo
authors.forename: Yuwei
authors.initials: Y
authors.lastname: Fan
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Zhang
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Hagan
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Xu
mesh_terms: D003188:Composite Resins / Q000138:chemical synthesis / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D004548:Elasticity; D005898:Glass; D008422:Materials Testing; D055595:Mechanical Phenomena; D057139:Nanofibers / Q000737:chemistry*; D018583:Pliability; D058105:Polymerization; D012212:Rheology; D012822:Silicon Dioxide; D014783:Viscosity; D015019:Yttrium; D015040:Zirconium
chemical_list: D003188:Composite Resins; C009753:fiberglass; D003776:Dental Porcelain; D015019:Yttrium; D012822:Silicon Dioxide; D015040:Zirconium; C028541:zirconium oxide; C091417:yttria