title: The influence of one-step polishing systems on the surface roughness and microhardness of nanocomposites.
abstract: OBJECTIVE
  This in vitro study evaluated the surface roughness and microhardness of nanocomposites that contain nanoparticles and a microhybrid composite finished and polished with two different one-step polishing systems and a conventional multi-step polishing system.
  
  
  METHODS
  The materials evaluated were Filtek Supreme XT, Grandio, Ceram X, Aelite Aesthetic Enamel, Tetric EvoCeram and Filtek Z250. A total of 240 specimens (10-mm in diameter, 2 mm thick) were fabricated for both tests (n=120 each test) in a plexiglass mold covered with a Mylar strip. After polymerization, five specimens per group received no polishing treatment and served as the control for both tests. For each composite group (n=15), the specimens were randomly divided into three polishing systems: PoGo, OptraPol and Sof-Lex. All polishing systems were applied according to the manufacturers' instructions after being ground wet with 1200 grid silicon carbide paper. The surface roughness values were determined using a profilometer. The microhardness measurements were performed using a digital microhardness tester (load 500 g; dwell time 15 seconds). The data were analyzed using the one-way ANOVA test at a significance level of 0.05 for both tests. Multiple comparison was performed with the Duncan Multiple Range test.
  
  
  RESULTS
  The smoothest surfaces were achieved under Mylar strips in all composite groups (p<0.05). There were no statistically significant differences between polishing systems in the Filtek Supreme XT, Ceram X, Aelite Aesthetic Enamel and Grandio groups for surface roughness (p>0.05). In the Tetric EvoCeram group, Sof-Lex exhibited the highest roughness values. No statistically significant differences were evaluated between polishing systems (p>0.05); whereas, the surfaces under Mylar Strip showed statistically significant lower values than the polished surfaces in terms of microhardness (p<0.05).
  
  
  CONCLUSIONS
  One-step polishing systems may be successfully used for polishing nanocomposites.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Baskent University, Ankara, Turkey. yoncako@yahoo.com
authors.forename: Yonca
authors.initials: Y
authors.lastname: Korkmaz
authors.forename: Emre
authors.initials: E
authors.lastname: Ozel
authors.forename: Nuray
authors.initials: N
authors.lastname: Attar
authors.forename: Gokhan
authors.initials: G
authors.lastname: Aksoy
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D003775:Dental Polishing / Q000379:methods*; D003799:Dental Stress Analysis; D006244:Hardness; D053761:Nanocomposites; D011897:Random Allocation; D018709:Statistics, Nonparametric; D013499:Surface Properties
chemical_list: D003188:Composite Resins