title: Two-body wear of monolithic, veneered and glazed zirconia and their corresponding enamel antagonists.
abstract: OBJECTIVE
  This study tested whether the two-body wear of monolithic zirconia and their corresponding enamel antagonists was higher compared to monolithic alloy and veneered zirconia.
  
  
  METHODS
  Cylindrical specimens (N = 36, n = 6) were prepared out of (A) veneered zirconia (VZ), (B) glazed zirconia using a glaze ceramic (GZC), (C) glazed zirconia using a glaze spray (GZS), (D) manually polished monolithic zirconia (MAZ), (E) mechanically polished monolithic zirconia (MEZ) and (F) monolithic base alloy (control group, MA). Wear tests were performed in a chewing simulator (49 N, 1.7 Hz, 5°C/50°C) with enamel antagonists. The wear analysis was performed using a 3D profilometer before and after 120,000, 240,000, 640,000 and 1,200,000 masticatory cycles. SEM images were used for evaluating wear qualitatively. The longitudinal results were analysed using linear mixed models (α = 0.05).
  
  
  RESULTS
  Materials (p < 0.001) and number of masticatory cycles (p < 0.001) had a significant effect on the wear level. The least enamel antagonist wear was observed for MAZ and MEZ (27.3 ± 15.2, 28 ± 11.1 μm, respectively). GZC (118 ± 30.9 μm) showed the highest wear of enamel antagonists. The highest wear rate in the material was observed in GZS (91.3 ± 38.6 μm). While in the groups of MA, VZ, GZC and GZS 50% of the specimens developed cracks in enamel, it was 100% in MAZ and MEZ groups.
  
  
  CONCLUSIONS
  Polished monolithic zirconia showed lower wear rate on enamel antagonists as well as within the material itself but developed higher rates of enamel cracks.
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Institut of Social and Preventive Medicine, University of Zurich, Zurich, Switzerland. bogna.stawarczyk@zzm.uzh.ch
authors.forename: Bogna
authors.initials: B
authors.lastname: Stawarczyk
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
authors.forename: Felix
authors.initials: F
authors.lastname: Schmutz
authors.forename: Albert
authors.initials: A
authors.lastname: Trottmann
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Roos
authors.forename: Christoph H F
authors.initials: CH
authors.lastname: Hämmerle
mesh_terms: D003743:Dental Enamel / Q000473:pathology*; D003775:Dental Polishing; D003776:Dental Porcelain / Q000737:chemistry; D019554:Dental Restoration Wear; D003801:Dental Veneers; D016014:Linear Models; D008409:Mastication; D008422:Materials Testing; D013499:Surface Properties; D014072:Tooth Abrasion / Q000473:pathology*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide