title: Influence of contamination and cleaning on bond strength to modified zirconia.
abstract: OBJECTIVE
  To evaluate the influence of contamination and cleaning procedures on shear bond strength (SBS) to modified zirconia surfaces.
  
  
  METHODS
  One hundred zirconium-oxide ceramic disks fabricated with a rough modified surface (Nobel Bond), which allows more micromechanical interlocking for adhesive cementation, were divided into five groups. Groups were contaminated with organic (OC; human blood and saliva) and/or inorganic contaminants (IC; type IV dental stone). For cleaning, modified surfaces were etched with phosphoric acid for 1min (PA) or fired in a ceramic furnace up to 910 degrees C and cleaned in an ultrasonic bath in ethanol (FU). Following combinations of contamination and cleaning protocols were chosen: group 1: OC-PA; group 2: IC-FU; group 3: OC+IC-PA+FU; group 4: OC+IC-no cleaning; group 5: no contamination-no cleaning. Level of contamination and efficacy of cleaning were evaluated using X-ray photoelectron spectroscopy (XPS). Composite cylinders were bonded to the disks using dual curing adhesive resin cement (RelyX ARC). Fifty samples were subjected to 20,000 thermal cycles (TC). All samples were tested for SBS. Statistical analysis was performed using one-way ANOVA with alpha=0.05.
  
  
  RESULTS
  SBS ranged from 16.6 to 18.8MPa (non-TC) and 10.6-21.7MPa (TC). TC did not lower SBS, except for group 1. XPS showed that OC produced higher levels of carbon, nitrogen, and silica, whereas IC generated elevated levels of calcium, sulfur, carbon, and potassium. Cleaning with both procedures reduced contamination significantly.
  
  
  CONCLUSIONS
  A combination of FU and PA is an efficient method for cleaning contaminated modified zirconia surfaces.
authors.affiliation: Department of Comprehensive Care, Case Western Reserve University - School of Dental Medicine, 10900 Euclid Avenue, Cleveland, OH 44106-4905, USA. jin-ho.phark@case.edu
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Phark
authors.forename: Sillas
authors.initials: S
authors.lastname: Duarte
authors.forename: Harold
authors.initials: H
authors.lastname: Kahn
authors.forename: Markus B
authors.initials: MB
authors.lastname: Blatz
authors.forename: Avishai
authors.initials: A
authors.lastname: Sadan
mesh_terms: D000134:Acid Etching, Dental; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001769:Blood; D002133:Calcium Sulfate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D004577:Electron Probe Microanalysis; D004866:Equipment Contamination; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012463:Saliva; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014465:Ultrasonics; D014867:Water / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; C113300:TPH hybrid; D014867:Water; D003776:Dental Porcelain; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D015040:Zirconium; C030242:phosphoric acid; C028541:zirconium oxide; D002133:Calcium Sulfate