Objectives: Ceramic-titanium systems are increasingly used, but little is known about the microstructure and composition of the system. The aim of our study was to investigate the topography and chemical composition of machine-milled cp Ti and casted cp Ti using surface analytical techniques (CLSM, XPS, Metastable Induced Electron Spectroscopy (MIES), SEM and Scanning Force Microscopy (SFM). Methods: After ultramorphological characterization of the two analyzed cp Ti specimens this study compared the bond strengths among cast titanium/Vita porcelain, and machine-milled titanium/Vita porcelain combinations and investigated the mode of bond failure of these combinations. A three-point flexural test were used to observe interface state after 1hrs thermal expansions (te), 1(st1) and 3 month (st3) storage at 37°C, thermocycling (5000 times at 55°C). Completely debonded specimens and longitudinally sectioned specimens were studied with SEM to determine the mode of bond failure. Results: There was a significant difference in the bond strengths of porcelain bonded to machine-milled cp Ti (te=15,0MPa+/-5,0; st1=19,6MPa +/-7,4; st3=15,9MPa +/-6,3; therm=14,4 MPa+/-5,5) and to casted cpTi (te=15,3MPa+/-7,6; st1=13,6MPa +/-8,5; st3=8,3MPa +/-4,1; therm=14,4MPa+/-5,5MPa). From the CLSM- and SEM- analyzes it appears that the diameter of the pits varied in the range of 0,1 to 10 µm. MIES showed the presence of Ti, O and C. The Ti-surface is covered by a 3-5 nm thick TiO2 layer. Conclusions: The results suggest a two-layer structure for the passive film formed on titanium after exposition. The inner layer has a structure close to TiO2, while the outlayer is dominated by CH2-groups with a few -C=O groups inside the hydrocarbon overlayer. The granular structure seems to indicate defects in the passive film influencing the Ti surfaces.

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