title: Finishing systems on the final surface roughness of composites.
abstract: OBJECTIVE
  This study evaluated differences in surface roughness of a microhybrid (Gradia Direct, GC America) and a nanofil (Filtek Supreme, 3M ESPE) composite using four polishing systems: PoGo/Enhance (DENTSPLY/Caulk), Sof-Lex (3M ESPE), Astropol (Ivoclar Vivadent), and Optidisc (KerrHawe).
  
  
  METHODS
  An aluminum mold was used to prepare 2 X 60 composite disks (10 mm X 2 mm). Composite was packed into the mold, placed between two glass slabs, and polymerized for 40 seconds from the top and bottom surfaces. Specimens were finished to a standard rough surface using Moore's disks with six brushing strokes. Specimens were rinsed and stored in artificial saliva in individual plastic bags at 36 degrees C for 24 hours prior to testing. Specimens were randomly assigned to one of the four polishing systems and were polished for 30 seconds (10 seconds per grit) with brushing strokes according to the manufacturer's instructions. Mean surface roughness (Ra) was recorded with a surface-analyzer 24 hours after storage in artificial saliva, both before and after polishing. Means were analyzed using two-way and one-way analysis of variance (ANOVA) and Tukey multiple comparison tests at p < 0.05.
  
  
  RESULTS
  There was a statistically significant difference for baseline measures between Filtek and Gradia (p=0.0338). For Filtek, Sof-Lex provided a significantly smoother surface (Ra=0.80 +/- 0.21) than Optidisc (Ra=0.93 +/- 0.28), Astropol (Ra=1.15 +/- 0.24), and Pogo/Enhance (Ra=1.39 +/- 0.39). For Gradia, Sof-Lex provided a significantly smoother surface (Ra=0.47 +/- 0.09) and Astropol provided a significantly rougher surface (Ra=1.39 +/- 0.19) than Pogo/Enhance (Ra=1.11 +/- 0.20) and Optidisc (Ra=1.15 +/- 0.18). There was no significant difference in roughness between composites for individual polishing systems (p=0.3991).
  
  
  CONCLUSIONS
  Filtek specimens were smoother than Gradia specimens after baseline roughening. Sof-Lex provided the smoothest final surface when used with either composite. Astropol provided a rough surface for Gradia specimens.
authors.affiliation: Department of Periodontics and Oral Medicine of the School of Dentistry at the University of Michigan in Ann Arbor, MI, USA. rkoh@umich.edu
authors.forename: Richard
authors.initials: R
authors.lastname: Koh
authors.forename: Gisele
authors.initials: G
authors.lastname: Neiva
authors.forename: Joseph
authors.initials: J
authors.lastname: Dennison
authors.forename: Peter
authors.initials: P
authors.lastname: Yaman
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D003775:Dental Polishing / Q000379:methods*; D003793:Dental Restoration, Permanent / Q000379:methods*; D053761:Nanocomposites; D011897:Random Allocation; D018709:Statistics, Nonparametric; D013499:Surface Properties
chemical_list: D003188:Composite Resins; C474035:Filtek Supreme; C470230:Gradia