title: Wear behavior of dental Y-TZP ceramic against natural enamel after different finishing procedures.
abstract: OBJECTIVE
  The aim of this in vitro study was to evaluate the influence of different finishing procedures on the wear behavior of zirconia against natural enamel.
  
  
  METHODS
  64 quadratic specimens (10 mm × 10 mm × 2 mm) were cut from a commercial hipped dental Y-TZP ceramic. Four different groups with 16 specimens each were formed according to the following finishing procedures: PZ (polished), RR (fine-grit diamond), GR (coarse-grit diamond), GZ (glazed). Polished specimens of a leucite-reinforced glass ceramic (Empress CAD) were used as a control (GC). The materials were subjected to the Ivoclar wear method (Willytec chewing simulator, 120,000 cycles, 5kg weight) with 80 natural caries-free cusps of first upper molars as antagonists. Wear was analyzed for both the enamel cusps and test specimens by measurement of the vertical substance loss with a laser scanner. Surface roughness was measured by means of a white-light interferometer.
  
  
  RESULTS
  The surface roughness was significantly different among the polished, diamond-finished, and glazed ceramic specimens (ANOVA, post hoc Bonferroni p<0.05). The results of the one-way ANOVA indicated that the finishing technique significantly affected enamel wear (p<0.05). The post hoc test indicated that the specimens finished with the coarse diamond caused significantly higher antagonist wear than the polished ones. Polished zirconia showed the lowest wear of the antagonist enamel, with a mean value of 171.74 (SD = 121.68), and resulted in enamel wear that was not significantly different from that of the glass ceramic control group. No significant linear correlation could be found between pre-testing surface roughness and abrasive wear.
  
  
  CONCLUSIONS
  If zirconia is used without veneering material for crowns and fixed dental prostheses (FDPs), the surface must be well-polished if occlusal adjustments with coarse diamonds are performed. The polishing step reduces the wear of the opposing enamel.
authors.affiliation: Department Prosthetic Dentistry, Danube Private University, Krems, Austria. gergo.mitov@dp-uni.ac.at
authors.forename: Gergo
authors.initials: G
authors.lastname: Mitov
authors.forename: Siegward D
authors.initials: SD
authors.lastname: Heintze
authors.forename: Stephanie
authors.initials: S
authors.lastname: Walz
authors.forename: Karsten
authors.initials: K
authors.lastname: Woll
authors.forename: Frank
authors.initials: F
authors.lastname: Muecklich
authors.forename: Peter
authors.initials: P
authors.lastname: Pospiech
mesh_terms: D000704:Analysis of Variance; D003743:Dental Enamel; D003775:Dental Polishing; D003776:Dental Porcelain; D019554:Dental Restoration Wear; D006801:Humans; D008409:Mastication; D008855:Microscopy, Electron, Scanning; D018709:Statistics, Nonparametric; D013499:Surface Properties; D015019:Yttrium; D015040:Zirconium
chemical_list: C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium