title: Effect of air-abrasion regimens and fine diamond bur grinding on flexural strength, Weibull modulus and phase transformation of zirconium dioxide.
abstract: OBJECTIVE
  This study evaluated the effect of air abrasion and polishing regimens on the flexural strength of yttrium stabilized polycrystalline tetragonal zirconia (Y-TZP).
  
  
  METHODS
  From Y-TZP blocks (InCeram 2000 YZ Cubes; Vita Zahnfabrik, Bad Säckingen, Germany) 120 bars (25 mm × 4 mm × 1.2 mm) were obtained according to ISO 6872:2008 and randomly divided into 4 groups: Group C: (control) without surface treatment (n = 30); Group APA: Air abrasion with aluminum oxide (44 µm) (n = 30); Group SC: Silica-coating (CoJet, 30 µm) (n = 30); Group FD: Fine diamond bur (n = 30). Subsequently, all specimens were subjected to 4-point bending test (in distilled water at 37 °C) in a universal testing machine (EMIC DL 1000; São José dos Pinhais, Paraná, Brazil); cross-head speed: 0.5 mm/min). The characteristic strength (σ0) of each specimen was obtained from the flexural strength test and evaluated using Weibull analysis. X-ray diffraction analysis was utilized to quantity the monoclinic phase. The surface topography of specimens was analyzed using 3D optical profilometer and scanning electron microscopy (SEM) after surface conditioning methods. The flexural strength data (σ4p) were statistically analyzed by 1-way ANOVA, Tukey test (α = 0.05) and Weibull (m = modulus, σ0 = characteristic strength) were calculated.
  
  
  RESULTS
  The mean ± standard deviations (MPa) of the groups were as follows: C: 1196.2 ± 284.2a; APA: 1369.7 ± 272.3a; SC: 1207.1 ± 229.7a and FD: 874.4 ± 365.4b. The values (m) and (σ0) were as follows: C: 4.5 and 1308.12; APA: 5.9 and 1477.88; SC: 6.0 and 1300.28; and FD: 2.6 and 985.901, respectively.
  
  
  CONCLUSIONS
  Air particle abrasion with neither silica nor alumina showed significant difference compared to the control group but grinding with fine diamond bur impaired the flexural strength of the zirconia tested.
authors.affiliation: Ingá University, Dental School, Post Graduate Program, Maringa - Brazil.
authors.forename: Silvia Masae de Araújo
authors.initials: SM
authors.lastname: Michida
authors.affiliation: São Paulo State University, São José dos Campos Dental School, Department of Dental Materials and Prosthodontics, São José dos Campos - Brazil.
authors.forename: Estevão Tomomitsu
authors.initials: ET
authors.lastname: Kimpara
authors.affiliation: Rio de Janeiro State University, Department of Mechanics and Energy, Technology Faculty, Resende - Brazil.
authors.forename: Claudinei
authors.initials: C
authors.lastname: dos Santos
authors.affiliation: Federal University of Rio Grande do Norte (UFRN), Department of Restorative Dentistry, Division of Prosthodontics, Natal - Brazil.
authors.forename: Rodrigo Othavio Assunção
authors.initials: RO
authors.lastname: Souza
authors.affiliation: São Paulo State University, São José dos Campos Dental School, Department of Dental Materials and Prosthodontics, São José dos Campos - Brazil.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.affiliation: University of Zurich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Zürich - Switzerland.
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
mesh_terms: D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing; D018130:Diamond; D033081:Shear Strength; D013499:Surface Properties; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D015019:Yttrium; D018130:Diamond; D015040:Zirconium; C028541:zirconium oxide