title: Evaluation of surface topography of zirconia ceramic after Er:YAG laser etching.
abstract: OBJECTIVE
  The aim of this study is to evaluate the effect of Erbium: yttrium-aluminum-garnet (Er:YAG) laser with different pulse lengths on the surface roughness of zirconia ceramic and airborne particle abrasion.
  
  
  BACKGROUND
  Er:YAG laser treatment is expected to be an alternative surface treatment method for zirconia ceramics; however, the parameters and success of the application are not clear.
  
  
  METHODS
  One hundred and forty zirconia discs (diameter, 10 mm; thickness, 1.2 mm) were prepared by a computer-aided design and computer-aided manufacturing (CAD/CAM) system according to the manufacturer's instructions. Specimens were divided into 14 groups (n=10). One group was left as polished control, one group was air-particle abraded with Al2O3 particles. For the laser treatment groups, laser irradiation was applied at three different pulse energy levels (100, 200, and 300 mJ) and for each energy level at four different pulse lengths; 50, 100, 300, and 600 μs. Surface roughness was evaluated with an optical profilometer and specimens were evaluated with scanning electron microscopy (SEM).
  
  
  RESULTS
  Data was analyzed with one way ANOVA and Tukey multiple comparison tests (α=0.05). For the 100 and 200 mJ laser etching groups, 50 and 100 μs laser duration resulted in significantly higher surface roughness compared with air-particle abrasion (p<0.05). The difference among Ra values of 300 μs, 600 μs, and air-particle abrasion groups were not statistically significant (p>0.05). For the 300 mJ laser etching groups; there was no statistically significant difference among the Ra values of 50 μs, 100 μs, 300 μs, 600 μs, and air-particle abrasion groups (p>0.05).
  
  
  CONCLUSIONS
  In order to increase surface roughness and promote better bonding to resin luting agents, Er:YAG laser etching may be an alternative to air-particle abrasion for zirconia ceramics. However, high levels of pulse energy and longer pulse length may have an adverse effect on micromechanical locking properties, because of a decrease in surface roughness.
authors.affiliation: Department of Prosthodontics, Istanbul University Faculty of Dentistry , Istanbul, Turkey .
authors.forename: Volkan
authors.initials: V
authors.lastname: Turp
authors.forename: Gokhan
authors.initials: G
authors.lastname: Akgungor
authors.forename: Deniz
authors.initials: D
authors.lastname: Sen
authors.forename: Betul
authors.initials: B
authors.lastname: Tuncelli
mesh_terms: D020906:Air Abrasion, Dental; D002516:Ceramics / Q000737:chemistry / Q000528:radiation effects*; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects; D053844:Lasers, Solid-State; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D019279:Resin Cements / Q000737:chemistry / Q000528:radiation effects; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry / Q000528:radiation effects*
chemical_list: D003764:Dental Materials; D019279:Resin Cements; D015040:Zirconium; C028541:zirconium oxide