Analysis of the element composition of the implant surfaces by means of energy-dispersive X-ray spectroscopy (EDX) was performed with an INCA Energy 350 system (Oxford Instruments, Wiesbaden, Germany) coupled with the SEM Quanta 200 FEG (Fig. 2). Similar to the micro-morphological presentation, each implant was divided into comparable sites of interest. Typical areas were selected and evaluated (Fig. 3). With the “Point &ID” mode of the INCA Energy software, both points of interest and the areas of interest are selected for the EDX analysis. Microscopic conditions (magnification × 2000) and excitation energy (HV 20 kV) are kept constant for all types of implants. For a semi-quantitative approach, the main components identified on all of the sample surfaces are evaluated as shown in Table 2. Intervals of minimum and maximum values are presented to demonstrate the high inhomogeneous situation found at most of the selected areas.

Evaluation of the zirconia implant surface roughness as well as their surface texture parameters is carried out by means of confocal laser scanning microscopic technique. A Leica TCS SP2 (Leica Microsystems, Wetzlar, Germany) upright microscope with a red He-laser (633 nm) and a high-performance objective (HC PL FLUOTAR × 50/0.80) was used to acquire high spatial resolution images (1024 × 1024 pixels). Image stacks are created by capturing all the light reflected from the deepest to the highest point of the selected sample surface area. The image stacks are created in defined steps and acquired for five uniformly distributed points at the circumferences of representative-treated and none-treated locations on each type of implant (compare Fig. 4). The step size was calculated for optically optimized values by the LCS Leica confocal software. Because of the cylindrically shaped surface character, a zoom factor of 2 which generates an image size of 150 × 150 μm was used to avoid artificial height values.

Maximum projections and height distribution images (depth map) are calculated by LCS software from the image stacks and viewed exemplary in Fig. 5.