title: Full-contour Y-TZP ceramic surface roughness effect on synthetic hydroxyapatite wear.
abstract: OBJECTIVE
  To investigate the effects of polishing techniques on the surface roughness of Y-TZP ceramic and on the wear behavior of synthetic hydroxyapatite (HA).
  
  
  METHODS
  Thirty-two full-contour Y-TZP (Diazir(®)) sliders (φ=2 mm × 1.5 mm in height) were manufactured using CAD/CAM, embedded in acrylic resin using brass holders, and randomly allocated into four groups (n=8): according to the finishing/polishing procedure: G1-as-machined, G2-glazed, G3-diamond bur finishing and G4-G3+OptraFine(®) polishing kit. Thirty-two sintered HA disks (φ=13 mm × 2.9 mm in height) were similarly mounted in brass holders. Y-TZP sliders baseline surface roughness values (Ra and Rq, in μm) were recorded using a non-contact profilometer (Proscan 2000). A two-body pin-on-disc wear test was performed. HA height (μm) and volume (mm(3)) losses were measured. Y-TZP height loss was measured using a digital micrometer. One-way ANOVA was used to determine the effect of the polishing techniques on the surface roughness. Comparisons between groups for differences in antagonist height loss/volume, and slider height loss were performed using one-way ANOVA. Statistical significance was set at α=0.05.
  
  
  RESULTS
  Roughness measurements showed significant differences (p=0.0001) among the surface treatments with G1 (Ra=0.84, Rq=1.13 μm) and G3 (Ra=0.89, Rq=1.2 μm) being the roughest, and G2 (Ra=0.42, Rq=0.63 μm) the smoothest (p=0.0001). Y-TZP slider height loss was highest for the glazed group (35.39 μm), and was lowest for the polished group (6.61 μm) (p=0.0001). Antagonist volume and height losses for groups (G1-G3) were similar, while the polished group (1.3 mm(3), 14.7 μm) showed significant lower values (p=0.0001).
  
  
  CONCLUSIONS
  Although glazed zirconia provides an initially smooth surface, significantly increased antagonist wear was observed compared to the polished Y-TZP zirconia surface.
authors.affiliation: Department of Restorative Dentistry (Graduate Operative), Indiana University School of Dentistry (IUSD), Indianapolis, IN 46202, USA.
authors.forename: Alaa H A
authors.initials: AH
authors.lastname: Sabrah
authors.forename: N Blaine
authors.initials: NB
authors.lastname: Cook
authors.forename: Palika
authors.initials: P
authors.lastname: Luangruangrong
authors.forename: Anderson T
authors.initials: AT
authors.lastname: Hara
authors.forename: Marco C
authors.initials: MC
authors.lastname: Bottino
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003775:Dental Polishing / Q000295:instrumentation / Q000379:methods; D018130:Diamond / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D018130:Diamond; D017886:Durapatite; D015040:Zirconium