title: Influence of Surface Conditioning Protocols on Reparability of CAD/CAM Zirconia-reinforced Lithium Silicate Ceramic.
abstract: OBJECTIVE
  To test the effect of surface conditioning protocols on the reparability of CAD/CAM zirconia-reinforced lithium silicate ceramic compared to lithium-disilicate glass ceramic.
  
  
  METHODS
  Zirconia-reinforced lithium silicate ceramic (Vita Suprinity) and lithium disilicate glass-ceramic blocks (IPS e.max CAD) were categorized into four groups based on the surface conditioning protocol used. Group C: no treatment (control); group HF: 5% hydrofluoric acid etching for 60 s, silane (Monobond-S) application for 60 s, air drying; group HF-H: 5% HF acid etching for 60 s, application of silane for 60 s, air drying, application of Heliobond, light curing for 20 s; group CO: sandblasting with CoJet sand followed by silanization. Composite resin (Tetric EvoCeram) was built up into 4 x 6 x 3 mm blocks using teflon molds. All specimens were subjected to thermocycling (5000x, 5°C to 55°C). The microtensile bond strength test was employed at a crosshead speed of 1 mm/min. SEM was employed for evaluation of all the debonded microbars, the failure type was categorized as either adhesive (failure at adhesive layer), cohesive (failure at ceramic or composite resin), or mixed (failure between adhesive layer and substrate). Two-way ANOVA and the Tukey's HSD post-hoc test were applied to test for significant differences in bond strength values in relation to different materials and surface pretreatment (p < 0.05).
  
  
  RESULTS
  The highest microtensile repair bond strength for Vita Suprinity was reported in group CO (33.1 ± 2.4 MPa) and the lowest in group HF (27.4 ± 4.4 MPa). Regarding IPS e.max CAD, group CO showed the highest (30.5 ± 4.9 MPa) and HF the lowest microtensile bond strength (22.4 ± 5.7 MPa). Groups HF, HF-H, and CO showed statistically significant differences in terms of all ceramic types used (p < 0.05). The control group showed exclusively adhesive failures, while in HF, HF-H, and CO groups, mixed failures were predominant.
  
  
  CONCLUSIONS
  Repair bond strength to zirconia-reinforced lithium silicate ceramics and lithium-disilicate glass ceramic could be improved when ceramic surfaces are sandblasted with CoJet sand followed by silanization.
authors.forename: Rana
authors.initials: R
authors.lastname: Al-Thagafi
authors.forename: Walid
authors.initials: W
authors.lastname: Al-Zordk
authors.forename: Samah
authors.initials: S
authors.lastname: Saker
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000179:Acrylates / Q000737:chemistry; D000268:Adhesiveness; D000537:Aluminum Oxide / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry; D017076:Computer-Aided Design; D045662:Dental Etching / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012821:Silanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000179:Acrylates; D003188:Composite Resins; D003764:Dental Materials; C520133:IPS e.max CAD LT; D012821:Silanes; C501891:Tetric EvoCeram; C493120:lithia disilicate; D003776:Dental Porcelain; C023506:Glass ceramics; C040415:heliobond; D015040:Zirconium; D000537:Aluminum Oxide; D006858:Hydrofluoric Acid; C028541:zirconium oxide