This study was designed to investigate the surface properties and the thickness of organofunctional silane films formed on leucite-reinforced feldspathic (LRF) ceramic surfaces after different methods of silane application using X-ray photoelectron spectroscopy (XPS). Six LRF ceramic discs (Mirage (R), Myron Intl., Kansas City, KS, USA) were produced according to the manufacturer's instructions and polished to a 1 mu m finish. A silane coupling agent was applied to five ceramic discs using different application methods: (A) immersion in silane solution for 60 s and dried with compressed air spray for 15 s; (B) as method A but heat treated with hot air at 50 +/- 5 degrees C for 15 s; (C) silane was applied with a brush for 60 s and dried with compressed air spray for 15 s; (D) as method C but heat treated with hot air at 50 +/- 5 degrees C for 15 s; (E) as method C followed by rinsing the specimens with hot water (15 s) and drying with hot air for 30 s. The ceramic surfaces were then analyzed by XPS at 15 degrees-60 degrees take-off angles. The results showed the highest and the lowest increase of C(1s) (C in the structure of silane) for treatments A and E, respectively. Signals of COO or C-COO in the high resolution spectra of C1s were observed for all silane-treated ceramic surfaces. The proportion of C-Si groups on the silane-treated surfaces compared with the untreated surface was significantly increased. XPS analysis indicates that the thickness of the silane film on a leucite-reinforced feldspathic ceramic surface is a function of the mode of application. The lowest film thickness of silane was found for treatment E, which more closely matches that of a monolayer. (C) Koninklijke Brill NV, Leiden, 2009