title: The Effect of Sandblasting, Er:YAG Laser, and Heat Treatment on the Mechanical Properties of Different Zirconia Cores.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of surface and heat treatments on the mechanical properties and phase transformation of yttria-stabilized tetragonal zirconia (Y-TZP) materials.
  
  
  BACKGROUND
  Zirconia is exposed to several treatments during dental application process. Knowing the effect of applied treatments on zirconia is essential for clinical success.
  
  
  METHODS
  Forty disk specimens of Zirkonzahn (Z) and DC-Zirkon (DC) materials were fabricated. The specimens were randomly divided into four groups according to surface [control, sandblasting, Erbium: Yttrium Aluminum Garnet (Er:YAG) laser irradiation] and heat (firing) treatments. The surface roughness (Ra, μm) was measured using a surface profilometer. The relative amount of the transformed monoclinic (m) phase was analyzed by X-ray diffractometry (XRD). Biaxial flexural strength was tested using piston-on-three-ball technique. The data were analyzed with the Kruskal-Wallis H test with Bonferroni correction, and the Mann-Whitney U test was used for pairwise comparisons.
  
  
  RESULTS
  There were no significant differences in surface roughness among the treated groups (p > 0.05), whereas sandblasting showed higher surface roughness than other treatments for both materials. Scanning electron microscopic (SEM) analyses revealed changes in surface morphology after surface treatments, especially in laser groups with the formation of cracks, and in sandblasting groups with the formation of microretentive grooves. The greatest amount of the monoclinic phase was measured after sandblasting (8.13%) for Z and (19.8%) for DC. The monoclinic phase reverted to the tetragonal phase after heat treatment. Heat treatment groups showed significantly lower flexural strength than other treatments (p < 0.05).
  
  
  CONCLUSIONS
  Heat and surface treatments influenced the mechanical properties of zirconia ceramic. The biaxial flexural strength and crystalline phase of materials decreased after heat treatments.
authors.affiliation: 1 Department of Prosthodontics, Faculty of Dentistry, Recep Tayyip Erdogan University , Rize, Turkey .
authors.forename: İpek
authors.initials: İ
authors.lastname: Çağlar
authors.affiliation: 2 Department of Prosthodontics, Faculty of Dentistry, Atatürk University , Erzurum, Turkey .
authors.forename: Nuran
authors.initials: N
authors.lastname: Yanıkoğlu
mesh_terms: D045662:Dental Etching / Q000379:methods*; D003764:Dental Materials / Q000528:radiation effects*; D006979:Hyperthermia, Induced; D053844:Lasers, Solid-State; D008422:Materials Testing; D013499:Surface Properties / Q000528:radiation effects; D015040:Zirconium / Q000528:radiation effects*
chemical_list: D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide