Assessment Of Depth-Profile After Silane Application On A Polymer-Based Material

Objectives: To assess the depth-profile of silane application on the non-pre-treated and pre-treated surface of a polymer-based material used to computer-aided-design/computer-aided-manufacturing (CAD/CAM) restorations.
Methods: A polymer-based material (Lava Ultimate-3M ESPE) containing silica- and zirconia-nanoclusters was selected. The material was submitted to five different surface pre-treatment prior to the application of a methacryloxypropyltrimethoxysilane (RelyX Ceramic Primer-3M ESPE) and a bis-(triethoxysilyl)-ethane (Monobond Etch & Prime-Ivoclar-Vivadent). The surfaces of all samples were pre-treated as follow: control group polished up to 1200 Sic-paper (LVUCO); thirty seconds of 9.6% hydrofluoric acid applied onto the surface (LVUAC); the surface was air-abraded at 2 bar pressure with 50 µm aluminum-oxide particles for 5 seconds at 10 mm distance (LVUSB); to the surface bis-(triethoxysilyl)-ethane was applied following manufacturing instructions (LVUMP); the surface was air-abraded as described and followed by acid etching for 90 seconds (LVUSA). To the samples excluding the LVUMP received active application of methacryloxypropyltrimethoxysilane. The samples with methacryloxypropyltrimethoxysilane plus the sample which received bis-(triethoxysilyl)-ethane application were submitted to depth profile in x-ray photoelectron spectroscopy (XPS). The other samples without methacryloxypropyltrimethoxysilane were analyzed in the scanning electron microscope/energy-dispersive x-ray spectroscopy (SEM/EDXS).
Results: The EDXS control group presented weight (wt) concentration on the total of 18.83% for carbon, 25.36% for silicon, and 15.52% for zirconium. All groups when surveyed on the XPS after application of both silanes, presented initially elevated carbon wt concentration in comparison with EDXS, with the exception of LVUSA. All the groups after sputtered for 70 nm depth presented their concentrations of carbon and silicon similar to what was initially found in the EDXS analyses without silane application.
Conclusions: The depth penetration of silane seems not to be influenced by the pre-treatment methods applied onto the surface. However, the pre-treatment would create a higher surface area where the silane will be deposited into the peaks and valleys.