title: Evaluation of spatial and functional roughness parameters on air-abraded zirconia as a function of particle type and deposition pressure.
abstract: OBJECTIVE
  This study evaluated the spatial and functional roughness parameters on air-abraded zirconia as a function of particle type and deposition pressure.
  
  
  METHODS
  Polished zirconia blocks (Cercon, Degussa/Dentsply) (N=30) with dimensions of 5 × 4 × 4 mm3 were air abraded according to 2 factors: a) particle type - 30-μm silica-coated alumina (CoJet) or alumina particles (45 μm); b) deposition pressure (1.5, 2.5 and 4.5 bar). Roughness parameters (Sdr, Vi, Sci and Svi) were measured in an optical profilometer (Wyko NT 1100) at the center of the air-abraded area (301.3 × 229.2 μm). Two measurements were made for each parameter from each surface. The means of each group were analyzed by 2-way ANOVA followed by Tukey's adjustment test and Student's t-test (alpha = 0.05).
  
  
  RESULTS
  Both the particle type (p < 0.05) and deposition pressure (p < 0.05) significantly affected the roughness parameters. Interaction terms were significant except for Sci and Svi. With the increase in pressure from 1.5 to 4.5 bar, Sdr (CoJet 1.5: 15.7 ± 0.2; CoJet 4.5: 26.6 ± 0.2; alumina 1.5: 14.7 ± 0.2; alumina 4.5: 24.4 ± 0.2) and Vi (CoJet 1.5: 0.66 ± 0.01; CoJet 4.5: 1.37 ± 0.07; alumina 1.5: 0.62 ± 0.02; alumina 4.5: 1.19 ± 0.02) parameters showed a significant increase with both alumina and CoJet particles. Mean Sci values (CoJet 1.5: 1.62 ± 0.01, CoJet 4.5: 1.49 ± 0.02; alumina 1.5: 1.6 ± 0.03; alumina 4.5: 1.42 ± 0.04) and SVi (CoJet 1.5: 0.98 ± 0.01, CoJet 4.5: 0.112 ± 0.01; alumina 1.5: 0.98 ± 0.01, alumina 4.5: 0.12 ± 0.01) decreased significantly (p < 0.05) with the increase in pressure from 1.5 to 4.5 bar. The pressure increase from 2.5 to 4.5 bar did not cause any significant difference (p > 0.05) in these parameters for either particle type.
  
  
  CONCLUSIONS
  Considering roughness parameters for micromechanical retention and parameters for adsorption mechanisms of adhesion, zirconia surfaces presented better morphological features when air abraded with silica-coated alumina than alumina particles at pressures higher than 1.5 bar. Particle deposition at 2.5 bar may be preferable to 4.5 bar pressure for avoiding possible deposition-related damage on zirconia, as there were no significant differences for the functional parameters.
authors.forename: José Renato Cavalcanti
authors.initials: JR
authors.lastname: Queiroz
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Botelho
authors.forename: Samira Albuquerque de
authors.initials: SA
authors.lastname: Sousa
authors.forename: Antonio Eduardo
authors.initials: AE
authors.lastname: Martinelli
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
mesh_terms: D000388:Air; D000537:Aluminum Oxide / Q000737:chemistry; D045662:Dental Etching / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry*; D006801:Humans; D010316:Particle Size; D011312:Pressure; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D012822:Silicon Dioxide; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide