title: [Improving bonding of zirconia through deposition of silica layer via collosol-gelatin process, the roles of NaHCO3].
abstract: OBJECTIVE
  To evaluate the effects of NaHCO3 on gelation of silica sols and shear bond strength of silica coated zirconia via collosol-gelatin (Sol-Gel) process.
  
  
  METHODS
  The gelation time of silica sols after being mixed with 1%, 3%, 5%, 7%, 10% concentrations of NaHCO3 was recorded. The one got the shortest gelation time was used for the following tests. Zirconia blocks were prepared and divided into five experimental groups according to surface conditioning methods: group A, alumina sandblasting; group B, sandblasting + tribochemical silica coating + silane; group C, sandblasting + silica coating via Sol-Gel process + silane; group D, sandblasting + silica coating via Sol-Gel process (NaHCO3 was used) + silane; group E, sandblasting + zirconia primer. A composite resin column was bonded on the treated zirconia surface with Bis-GMA based composite resin cement. All specimens were subjected to shear bond strength (SBS) tests.
  
  
  RESULTS
  The shortest gelation time of silica sols were found when silica sols was mixed with 10% NaHCO3. Group A showed the lowest SBS values of (4.12 ± 0.52) MPa, which was significant different from SBS of group B [(10.24 ± 2.78) MPa], C [(7.36 ± 1.59) MPa], D [(9.79 ± 2.07) MPa], D [(8.39 ± 0.49) MPa], and no statistical difference was found between group C and D.
  
  
  CONCLUSIONS
  The silica coating via Sol-Gel process can significantly improve the bond strength of zirconia, and NaHCO3 would not exert influences to bonding.
authors.affiliation: Institute of Stomatology, Nanjing Medical University & Department of Prosthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Xie
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.forename: Fei-Min
authors.initials: FM
authors.lastname: Zhang
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry; D033081:Shear Strength; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D017693:Sodium Bicarbonate / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D003188:Composite Resins; D012821:Silanes; D003776:Dental Porcelain; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D017693:Sodium Bicarbonate; D005780:Gelatin; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide