title: Effect of incorporation of silane in the bonding agent on the repair potential of machinable esthetic blocks.
abstract: OBJECTIVE
  To investigate the repair potential of CAD/CAM (computer-aided design/computer-aided manufacturing) ceramic and composite blocks using a silane-containing bonding agent with different repair protocols.
  
  
  METHODS
  Twenty-four discs were constructed from CAD/CAM ceramic and composite blocks. The discs were divided into six groups according to surface pre-treatment employed; GI: Diamond stone roughening (SR), GII: SR+ silanization (SR+S), GIII: Hydrofluoric acid etching (HF), GIV: HF+ silanization (HF+S), GV: Silica coating (SC), GVI: SC+ silanization (SC+S). Silane-containing bonding agent (Single Bond Universal adhesive, 3M ESPE) was applied to the pre-treated discs. Prior to light curing, irises were cut from tygon tubes (internal diameter = 0.8 mm and height = 0.5 mm) and mounted on each treated surface. Nanofilled resin composite (Filtek Z350(XT), 3M ESPE) was packed into the cylinder lumen and light-cured (n = 10). The specimens were subjected to microshear bond strength testing (μ-SBS) using universal testing machine. Failure modes of the fractured specimens were analyzed using field emission scanning electron microscope (FESEM). Eight representative discs were prepared to analyze the effect of surface treatments on surface topography using FESEM. μ-SBS results were analyzed using ANOVA and Tukeys post-hoc test.
  
  
  RESULTS
  Three-way ANOVA results showed that the materials, surface pre-treatment protocols, and silanization step had a statistically significant effect on the mean μ-SBS values at P ≤ 0.001. For ceramic discs, the groups were ranked; GIV (24.45 ± 7.35)> GVI ((20.18 ± 2.84)> GV (7.14 ± 14)= GII (6.72 ± 1.91)=GI (6.34 ± 2.21)=GIII (5.72 ± 2.18). For composite discs, groups were ranked; GI (24.98 ± 7.69)=GVI (24.84 ± 7.00) >GII (15.85 ± 5.29) =GV (14.65 ± 4.5)= GIV (14.24 ± 2.95)≥ GIII ((9.37 ± 2.78).
  
  
  CONCLUSIONS
  The additional silanization step cannot be omitted if the repair protocol comprises of either hydrofluoric acid etching or silica coating for both CAD/CAM esthetic restorative materials. However, this step can be suppressed by using silane-containing adhesive with diamond stone roughened repair protocol.
authors: Department of Fixed Prosthodontic, Misr International University, Cairo, Egypt.
authors: Hanaa
authors: H
authors: Zaghloul
authors: Department of Operative Dentistry, Misr International University, Cairo, Egypt.
authors: Dina Wafik
authors: DW
authors: Elkassas
authors: Department of Operative Dentistry, Cairo University, Cairo, Egypt.
authors: Mohamed Fouad
authors: MF
authors: Haridy
keywords: Computer-aided design/computer-aided manufacturing esthetic blocks; microshear bond strength; repair; scanning electron microscopy; silane