Evaluation of Surface Treatment Strategies on a Polymer-Infiltrated-Ceramic-Network

Objectives: The objective of this in vitro study was to assess the depth-profile of silane application and micro-shear bond strength after surface treatment strategies on a polymer-infiltrated-ceramic-network (PICN).
Methods: The PICN material Vita Enamic (ENA - Vita Zahnfabrik) for computer-aided-design/computer-aided-manufacturing (CAD/CAM) was selected to this study. A total of 50 specimens were fabricated. The material’s surface was treated with four different strategies in addition to the control group as follows (n=10): control group surface was polished up to -1200 Sic paper (CON); surface was etched with 9.6% hydrofluoric acid for 30 seconds (ACH); surface was air-abraded at 2 bar with aluminum oxide 50 µm particles for 5 seconds at 10 mm distance (SAB); surface was subjected to the application of bis-(triethoxysilyl)-ethane (Monobond Etch & Prime-Ivoclar-Vivadent) (MEP); on the surface a combination of air-abrasion followed by 9.6% hydrofluoric acid for 90 seconds was employed (SAC). Four composite pins were bonded on the surface after silane application. The set was submitted to micro-shear bond strength (µSBS) at 0.5 mm/min in the Ultratester (Ultradent Products) before and after thermocycling (THC). The fracture pattern was classified in mixed, cohesive, and adhesive. To the data two-way ANOVA was performed (α=5%). Another set of specimens for each surface strategy without the composite pins were submitted to depth profile in x-ray photoelectron spectroscopy (XPS).
Results: All surface treatment strategies significantly reduced the µSBS after THC (p<0.05). The highest mean before and after THC was showed by SAC (p<0.05). SAB and MEP were not statistically different between each other before and after THC (p>0.05). ACH showed the lowest means for the treated groups. Carbon presented a thicker layer when ENA was submitted to SAC.
Conclusions: SAC showed to be the more effective surface treatment among strategies employed. MEP should be considered to be applied in polymer-based materials.