title: Improving mechanical properties of flowable dental composite resin by adding silica nanoparticles.
abstract: OBJECTIVE
  The main drawback of flowable dental composite resin is low strength compared to conventional composite resin, due to a low amount of filler, neccessary for achieving low viscosity and ease of handling. The aim of this study was to improve mechanical properties of flowable dental composite resin by adding small amount of nanoparticles, which would not compromise handling properties.
  
  
  METHODS
  A commercially available flowable dental composite resin material was mixed with 7 nm aftertreated hydrophobic fumed silica and cured by an UV lamp. Four sets of samples were made: control sample (unmodified), the sample containing 0.05%, 0.2% and 1% nanosilica. Flexural modulus, flexural strength and microhardness were tested. One-way ANOVA followed by Tukey's test with the significance value of p < 0.05 was performed to statistically analyze the obtained results. Furthermore, differential scanning calorimetry (DSC) and SEM analysis were performed. To asses handling properties, slumping resistance was determined.
  
  
  RESULTS
  It was found that 0.05% is the most effective nanosilica content. All the tested mechanical properties were improved by a significant margin. On the other hand, when 0.2% and 1% nanosilica content was tested, different results were obtained, some of the mechanical properties even dropped, while some were insignificantly improved. The difference between slumping resistance of unmodified and modified samples was found to be statistically insignificant.
  
  
  CONCLUSIONS
  Low nanosilica addition proved more effective in improving mechanical properties compared to higher additions. Furthermore, handling properties are unaffected by nanosilica addition.
authors.affiliation: Department for Production Engineering, Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Balos
authors.forename: Branka
authors.initials: B
authors.lastname: Pilić
authors.forename: Branislava
authors.initials: B
authors.lastname: Petronijević
authors.forename: Dubravka
authors.initials: D
authors.lastname: Marković
authors.forename: Sinisa
authors.initials: S
authors.lastname: Mirković
authors.forename: Ivan
authors.initials: I
authors.lastname: Sarcev
mesh_terms: D000180:Acrylic Resins; D001696:Biomechanical Phenomena; D003188:Composite Resins; D066298:In Vitro Techniques; D053758:Nanoparticles; D011140:Polyurethanes; D012822:Silicon Dioxide; D014783:Viscosity
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; C111840:flowable hybrid composite; D012822:Silicon Dioxide