Objective : The overall goal of this research was to chemically modify the surface of zirconia dental ceramics with a Si x O y seed layer to increase adhesive bonding with commercially available silanes and resin cements.
Materials and methods : Investigation focused on a novel approach to functionalize the zirconia surface with Si x O y that would promote chemical bonding with traditional organo-silanes. Planar test structures were prepared, modified, and analyzed, before and after Si–O modification using X-ray photoelectron spectroscopy (XPS). Varying thicknesses of Si x O y were deposited on ZirCAD blocks and bonded to a similar dimension composite block. Microtensile bars were prepared and subjected to tensile forces, scanning electron microscopy (SEM) was used to analyze fracture surfaces and determine failure mode.
Results : XPS analysis revealed a level of bonded Si x O y to the surface of zirconia. Microtensile bond testing revealed that a thin (2.6 nm) Si x O y modification was similar in bond strength to the porcelain control group. Other groups tested had lower strength values and higher percentages of adhesive failures.
|Group||Peak stress (SD) (MPa)||Adhesive (%)||Mixed mode (%)||Cohesive (%)|
|Composite (bars only) a||29.2 (3.7)||Control|
|Porcelain – (control) b||25.3 (5.3)||16||35||49|
|Zirconia (Si x Oy – 2.6 nm thickness) b||23.2 (5.4)||15||40||45|
|Zirconia (CoJet treatment) c||18.6 (5.9)||32||52||16|
|Zirconia (Si x O y – 23 nm thickness) c||16.2 (5.9)||50||43||7|
|Zirconia (no treatment) d||7.6 (3.0)||72||28||–|