title: Characterization of a Diamond Ground Y-TZP and Reversion of the Tetragonal to Monoclinic Transformation.
abstract: OBJECTIVE
  To characterize the surface of an yttria-stabilized zirconia (Y-TZP) ceramic after diamond grinding in terms of its crystalline phase, morphology, mean roughness (Ra), and wettability as well as to determine a thermal treatment to reverse the resulting tetragonal to monoclinic (t-m) transformation.
  
  
  METHODS
  Y-TZP specimens were distributed into different groups according to the actions (or no action) of grinding and irrigation. Grinding was accomplished using a diamond stone at a low speed. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy, goniometry, and profilometry. In situ high-temperature XRD was used to determine an annealing temperature to reverse the t-m transformation. Ra was submitted to the Kruskal-Wallis test, followed by the Dunn test (α=0.05). The volume fraction of the monoclinic phase and contact angle were submitted to one-way analysis of variance, followed by the Tukey test (α=0.05).
  
  
  RESULTS
  Monoclinic zirconia was observed on the surface of samples after dry and wet grinding with a diamond stone. The volume fraction of the monoclinic phase was smaller on the dry ground samples (3.6%±0.3%) than on the wet ground samples (5.6%±0.3%). High-temperature XRD showed reversion of the t-m phase transformation, which started at 700°C and completed at 800°C in a conventional oven.
  
  
  CONCLUSIONS
  Grinding with a diamond stone partially transformed the crystalline phase on the surface of a Y-TZP ceramic from tetragonal to monoclinic zirconia while simultaneously increasing the surface roughness and wettability. The t-m transformation could be reversed by heat treatment at 800°C or 900°C for 60 minutes or 1000°C for 30 minutes.
authors.forename: L M
authors.initials: LM
authors.lastname: Candido
authors.forename: Lmg
authors.initials: L
authors.lastname: Fais
authors.forename: E B
authors.initials: EB
authors.lastname: Ferreira
authors.forename: S G
authors.initials: SG
authors.lastname: Antonio
authors.forename: Lap
authors.initials: L
authors.lastname: Pinelli
mesh_terms: D003460:Crystallization; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis; D003801:Dental Veneers; D018130:Diamond / Q000737:chemistry; D006358:Hot Temperature; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D017155:Wettability; D014961:X-Ray Diffraction; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D018130:Diamond; D015040:Zirconium