title: Evaluation of various polishing systems and the phase transformation of monolithic zirconia.
abstract: BACKGROUND
  Although a well-polished monolithic zirconia surface is essential, insufficient comparative studies on the constituents and efficacy of polishing systems have been conducted.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to analyze the abrasive constituents and compare the polishing effectiveness of 6 zirconia polishing systems, including their potential influence on the phase transformation of monolithic zirconia.
  
  
  METHODS
  The compositions of 6 zirconia polishing systems were analyzed using energy dispersive spectroscopy (EDS). Sintered and high-speed ground monolithic zirconia specimens were used as control groups (n=14 specimens per group). Test groups (n=168) were pretreated identically to the control group and arbitrarily divided into 12 groups to examine 6 polishing systems for 2 polishing periods (60 or 120 seconds). The surfaces were characterized by a surface profiler and various analytic techniques, including x-ray diffraction (XRD) analysis. The data were analyzed using 2-way ANOVA and multiple comparisons and the Bonferroni method (α=.05).
  
  
  RESULTS
  The abrasives were primarily composed of C, O, and Si. Diamond was identified as the main abrasive and SiC as the supplementary abrasive in the polishing systems. No significant differences were observed for the 60- or 120-second polishing times (P>.05). Four products had significantly lower surface roughness values than the other 2 (P<.001). The occlusal-adjustment-simulating pretreatment and polishing processes did not cause phase transformations in the zirconia specimens.
  
  
  CONCLUSIONS
  The monolithic zirconia polishing systems contained diamond and SiC abrasives. All zirconia polishing systems showed clinically acceptable results, and 4 systems exhibited lower surface roughness. Phase transformation did not occur during polishing procedure.
authors.affiliation: Assistant Professor, Department of Prosthodontics and Research Institute of Oral Science, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea.
authors.forename: Yoon-Hyuk
authors.initials: YH
authors.lastname: Huh
authors.affiliation: Professor, Department of Prosthodontics and Research Institute of Oral Science, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea.
authors.forename: Chan-Jin
authors.initials: CJ
authors.lastname: Park
authors.affiliation: Professor, Department of Prosthodontics and Research Institute of Oral Science, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea. Electronic address: lila@gwnu.ac.kr.
authors.forename: Lee-Ra
authors.initials: LR
authors.lastname: Cho
mesh_terms: D003775:Dental Polishing / Q000295:instrumentation / Q000379:methods*; D003793:Dental Restoration, Permanent / Q000295:instrumentation / Q000379:methods; D006801:Humans; D066298:In Vitro Techniques; D013052:Spectrometry, X-Ray Emission; D015040:Zirconium / Q000627:therapeutic use*
chemical_list: D015040:Zirconium; C028541:zirconium oxide