The impact of argon/oxygen low-pressure plasma on shear bond strength between a veneering composite and different PEEK materials

Objective. The aim of the study was to evaluate the impact of low-pressure argon/oxygen plasma with and without previous sandblasting on the shear bond strength (SBS) between dental PEEK compounds and a veneering composite. Methods. Of one type of unfilled PEEK and two pigment powder filled PEEK compounds, forty rectangular plates each were prepared and polished up to 4000 grit. The samples were randomly assigned to four surface pre-treatment groups, each consisting of ten specimens (1. Untreated; 2. Plasma treatment; 3. Sandblasting; 4. Sandblasting + plasma treatment). Plasma treatment was performed for 35 min using a low-pressure plasma system with a 1:1 mixture of the process gases argon and oxygen. Surface roughness and water contact angles were recorded. An adhesive (Visio.link, Bredent GmbH & Co KG, Senden, Germany) was applied onto the specimen surfaces and light cured. A mold was used to shape the veneering composite (Vita VM LC, Vita Zahnfabrik, Bad Sfickingen, Germany) into a cylindrical form on the sample surface before light curing. SBS was measured after 24h incubation at 37 degrees C in distilled water using a universal testing machine. Results. The samples pre-treated according to group 4 (sandblasting and plasma treatment) showed the highest SBS overall, whereas the unfilled PEEK showed the highest SBS (19.8 +/- 2.46 MPa) compared to the other PEEK materials (15.86 +/- 4.39 MPa and 9.06 +/- 3.1 MPa). Significance. Sandblasting and surface activation with low-pressure argon/oxygen plasma in combination with an adhesive causes a favorable increase in shear bond strength, especially on unfilled PEEK material. (C) 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.