A Novel Approach for Improvement of the Interfacial Binding of Ceramics for Dental Materials: Chemical Treatment and Oxygen Plasma Etching

Dental ceramic is one of the most widely used materials in the dental industry because of its extensive use in resin-bonded restorations and porcelain repair systems. In this study, two approaches were applied to dental ceramic surfaces for improvement in the wettability and surface energy of the effective resin-ceramic interfacial binding. One group of dental ceramics was treated by glow discharge with oxygen at a discharge power of 20 W and for an exposure time of 15 min. The other group was dipped onto hydrofluoric acid (HF) solution. Then, the samples were washed with distilled water and dried at the room temperature before the oxygen plasma treatment. The effectiveness of the two approaches was compared by means of changes in the surface wettability and polarity as measured by both the sessile drop and captive bubble techniques. Oxygen plasma treatment increased the surface wettability, but a greater increase was found with HF etching before the oxygen plasma treatment. This result was demonstrated by the decrease in the static contact angle as measured by the sessile drop technique (53.6 +/- 4.19 to 27.7 +/- 3.30). In addition, with the combination of the prechemical treatment with HF and the oxygen plasma treatment, the polarity increased more dramatically (0.706 +/- 0.013 to 0.845 +/- 0.008). The surface chemical composition and physical morphology were investigated by X-ray photoelectron spectroscopy and scanning electron microscopy. Furthermore, the HF etching before oxygen plasma treatment was found to improve the shear bond strength, and it was significantly stronger than that of the groups treated with oxygen only for the resin composite materials (p < 0.05). This two-step treatment could be a new approach for the activation of dental ceramic discs. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2656-2664, 2008