title: Long-term bond of glass ceramic and resin cement: evaluation of titanium tetrafluoride as an alternative etching agent for lithium disilicate ceramics.
abstract: OBJECTIVE
  To evaluate in vitro the effect of using titanium tetrafluoride as an alternative etchant prior to the silanization of the bonding surface on the long-term resin bond strength to lithium disilicate ceramic.
  
  
  METHODS
  Disk-shaped specimens made of lithium disilicate ceramic were ground with abrasive paper, then etched with aqueous solutions (2.5% and 5%) of titanium tetrafluoride for 60 s, 120 s and 240 s. Positive control specimens were etched with 5% hydrofluoric acid for 20 s and negative control specimens were not etched. Afterwards, bonding surfaces of all specimens were silanized. Plexiglas tubes filled with a composite resin were bonded to the specimens using an alignment apparatus and a composite luting resin. After storage in 37°C tap water for three days (n = 8) and after storage in 37°C tap water for 150 days interrupted by 5 x 7500 thermal cycles (n = 8), tensile bond strength (TBS) was measured in a universal testing machine at a crosshead speed of 2 mm/min.
  
  
  RESULTS
  After artificial aging, all specimens etched with titanium tetrafluoride debonded spontaneously resulting in a TBS of 0 MPa. Therefore, statistical analysis revealed a highly significant difference between the positive control and the test groups after 150 days storage.
  
  
  CONCLUSIONS
  Etching the bonding surface of lithium disilicate ceramic restorations with hydrofluoric acid is still a "gold standard" and cannot be replaced by titanium tetrafluoride.
authors.affiliation: Department of Prosthodontics, Christian-Albrechts University, Kiel, Germany. kklosa@proth.uni-kiel.de
authors.forename: Karsten
authors.initials: K
authors.lastname: Klosa
authors.forename: Ineke
authors.initials: I
authors.lastname: Boesch
authors.forename: Matthias
authors.initials: M
authors.lastname: Kern
mesh_terms: D003188:Composite Resins; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods*; D003776:Dental Porcelain; D003799:Dental Stress Analysis / Q000295:instrumentation; D005459:Fluorides; D006858:Hydrofluoric Acid; D008689:Methacrylates; D019279:Resin Cements; D012821:Silanes; D013718:Tensile Strength; D013997:Time Factors; D014025:Titanium
chemical_list: D003188:Composite Resins; D008689:Methacrylates; C509715:MultiCore Flow; D019279:Resin Cements; D012821:Silanes; C493120:lithia disilicate; D003776:Dental Porcelain; D014025:Titanium; D005459:Fluorides; D006858:Hydrofluoric Acid; C032240:titanium tetrafluoride