title: Evaluation of chemical treatment on zirconia surface with two primer agents and an alkaline solution on bond strength.
abstract: OBJECTIVE
  This study evaluated the effect of an alkaline solution and two 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primer agents on bond strength to zirconia (yttria-stabilized tetragonal zirconium polycrystal [Y-TZP]) through the shear bond strength (SBS) test.
  
  
  METHODS
  Sixty square-shaped Y-TZP samples were embedded in an acrylic resin mold, polished, and randomly assigned to one of six groups (n=10) according to treatment surface: group CR, no treatment (control); group NaOH, 0.5 M NaOH; group AP, Alloy Primer; group ZP, Z-Primer Plus; group NaOH-AP, 0.5 M NaOH + Alloy Primer; and group NaOH-ZP, 0.5 M NaOH + Z-Primer Plus. The resin cement (Rely X U100) was applied inside a matrix directly onto the Y-TZP surface, and it was light-cured for 40 seconds. The samples were stored in distilled water at 37°C for 24 hours prior to the test, which was performed in a universal machine at a crosshead-speed of 0.5 mm/min. The data were analyzed by one-way analysis of variance and Tukey tests (p<0.05). Light stereomicroscopy and scanning electron microscopy were used to assess the surface topography and failure mode.
  
  
  RESULTS
  The SBS was significantly affected by the chemical treatment (p<0.0001). The AP group displayed the best results, and the use of NaOH did not improve SBS results relative to either AP or ZP. The samples treated with Alloy Primer displayed mainly mixed failures, whereas those conditioned with Z-Primer Plus or with 0.5 M NaOH presented a balanced distribution of adhesive and mixed failure modes.
  
  
  CONCLUSIONS
  The use of a NaOH solution may have modified the reactivity of the Y-TZP surface, whereas the employment of a MDP/6-4-vinylbenzyl-n-propyl amino-1,3,5-triazine-2,4-dithione-based primer enhanced the Y-TZP bond strength.
authors.affiliation: Department of Prosthodontics, Bauru School of Dentistry, São Paulo University, Bauru, Brazil. fcesarlorenzoni@yahoo.com.br
authors.forename: F C
authors.initials: FC
authors.lastname: Lorenzoni
authors.forename: V P
authors.initials: VP
authors.lastname: Leme
authors.forename: L A
authors.initials: LA
authors.lastname: Santos
authors.forename: P C G
authors.initials: PC
authors.lastname: de Oliveira
authors.forename: L M
authors.initials: LM
authors.lastname: Martins
authors.forename: G
authors.initials: G
authors.lastname: Bonfante
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D017655:Silicon Compounds / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013871:Thiones / Q000737:chemistry; D013997:Time Factors; D014227:Triazines / Q000737:chemistry; D014867:Water / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000468:Alkalies; C521707:Alloy Primer; D017554:Carbon Compounds, Inorganic; D003764:Dental Materials; D008689:Methacrylates; D019279:Resin Cements; D017655:Silicon Compounds; D013871:Thiones; D014227:Triazines; C499362:yttria stabilized tetragonal zirconia; D014867:Water; D012972:Sodium Hydroxide; D015019:Yttrium; C069749:methacryloyloxydecyl dihydrogen phosphate; C076160:6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithiol; D015040:Zirconium; C022088:silicon carbide