title: Effect of nanofiller on wear resistance and surface roughness of resin composites.
abstract: OBJECTIVE
  To compare the wear resistance and surface roughness of nanofiller-containing composites and microhybrid composites after simulated wear.
  
  
  METHODS
  Five microhybrid composites and five nanofiller-containing resin composites were included in the study. Six cylindrical specimens with a diameter of 10 mm and a thickness of 6 mm for each material were prepared. The volume loss, vertical loss and the surface roughness (Ra) were determined after 800 cycles of simulated chewing motion. One specimen of each material was analysed by scanning electron microscopy (SEM) to compare the morphology of the wear surfaces. The microhybrid composites group and nanofiller-containing composites group were tested using the Mann-Whitney U test with a significance level of α = 0.05.
  
  
  RESULTS
  For all microhybrid composites, the average wear volume loss and vertical loss were 56.44 mm3 and 730.6 µm, respectively, while the average wear losses of nanofiller-containing composites were 40.15 mm3 and 528.17 µm, respectively. The nanofiller containing composite GNH400N showed the least roughness (Ra = 0.346 ± 0.076 µm), while the conventional microhybrid composite Ceramage showed the highest roughness (Ra = 0.699 ± 0.214 µm). However, wear resistance and surface roughness for the two groups showed no statistical difference. SEM micrographs of the nanofiller-containing composites after wear testing showed smoother and more uniform wear surfaces than for the microhybrid composites.
  
  
  CONCLUSIONS
  Nanofillers did not significantly influence the wear resistance of resin composites, but might improve the surface roughness of resin composites.
authors.affiliation: Peking University School, Beijing, People's Republic of China.
authors.forename: Jian Min
authors.initials: JM
authors.lastname: Han
authors.forename: Hong
authors.initials: H
authors.lastname: Lin
authors.forename: Gang
authors.initials: G
authors.lastname: Zheng
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Shinya
authors.forename: Harunori
authors.initials: H
authors.lastname: Gomi
authors.forename: Akikazu
authors.initials: A
authors.lastname: Shinya
authors.forename: Jie
authors.initials: J
authors.lastname: Lin
mesh_terms: D008855:Microscopy, Electron, Scanning; D049329:Nanostructures; D012117:Resins, Synthetic; D013499:Surface Properties
chemical_list: D012117:Resins, Synthetic