title: Indentation size effect of Y-TZP dental ceramics.
abstract: OBJECTIVE
  The purpose of this study was to investigate and analyze the indentation size effect (ISE) in Vickers hardness of monolithic yttria partially stabilized zirconia (Y-TZP) dental ceramics without and with the addition of dental dye A3. The ISE is analyzed using the Mayer law, a proportional specimen resistance (PSR) model and a modified proportional specimen resistance (MPSR) model.
  
  
  METHODS
  Two samples of Y-TZP dental ceramics, trade names BruxZir (provided by Glidewell Laboratories, CA, USA), were investigated. The first sample was polished Y-TZP and the second sample was polished Y-TZP with the addition of dental dye A3, by VITA Classical Shade Guide. The Vickers hardness was measured under the following loads: 0.49N, 0.98N, 1.96N, 4.90, 9.81N and 29.42N. Thirty indentations were made on each sample, under each load. Relationships between the applied load, F, and the resulting indentation size, d, have been analyzed by the Mayer law, the PSR model and the MPSR model.
  
  
  RESULTS
  The Meyer index (n) for both Y-TZP dental ceramics is less than 2, which indicates that hardness is dependent on test loads. The PSR model and the MPSR model were used to calculate "true" Vickers hardness or load-independent hardness.
  
  
  CONCLUSIONS
  All applied mathematical models are suitable for the data analysis, which is confirmed with high correlation coefficients, but the best correlation between measured values and mathematical models was achieved with the MPSR model with a correlation coefficient of 0.9999.
authors.affiliation: Department of materials, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb, Croatia.
authors.forename: Marijana
authors.initials: M
authors.lastname: Majić Renjo
authors.affiliation: Department of materials, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb, Croatia. Electronic address: lidija.curkovic@fsb.hr.
authors.forename: Lidija
authors.initials: L
authors.lastname: Ćurković
authors.affiliation: Dental Polyclinic Zagreb, Perkovčeva 3, Zagreb, Croatia.
authors.forename: Sanja
authors.initials: S
authors.lastname: Štefančić
authors.affiliation: Department of materials, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb, Croatia.
authors.forename: Danko
authors.initials: D
authors.lastname: Ćorić
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation; D006244:Hardness; D008422:Materials Testing; D008956:Models, Chemical; D013499:Surface Properties; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D003764:Dental Materials; C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015040:Zirconium
keywords: Ceramics; Indentation size effect; Monolithic zirconia; Vickers hardness; Y-TZP