SEM micrographs presented in Fig. 2 demonstrate the dissimilarity of the sample surface microstructure. Implant 1 shows an overall smoother surface and a slaty-like surface without evidence of a typical etching process. The surface shows sparse roughness. Implants 2–4 show deep markings from their brand’s specific etching and sandblasting processes. In × 10,000 magnification, immersions can be found that look like little craters. Implant 2 shows the biggest immersions, and implant 4 shows the smallest. In a × 25,000 magnification, implants 2–5 show droplet-like-shaped particles on the outer surface as a basic structure of the immersions under × 10,000 magnification. The finest droplets can be found on implant 2, and the biggest droplets can be found on implants 4 and 5. Implant 5 stands out from the other implants. It shows very evenly spread droplets on the surface in every magnification (Fig. 2).

The semi-quantitative element composition showed no significant impurity of any implant tested (Table 2). Both the machined and the rough areas (Fig. 3) were predominated by zirconium, oxygen, and carbon. Yttrium could be found in implants 1–3. Implants 4 and 5 showed yttrium under the detection limit and just less than 1.7 atomic % in the apical aspect of implant 4. Minor traces of hafnium could be shown in all implants 1–5. Implants 1, 4, and 5 showed traces of aluminum on the surface. The highest amount of aluminum could be found on the surface of implant 4.

CLSM images including the topological information of all five implants are shown in Fig. 4.

Untreated areas (machined areas) of implants 1–4 showed parallel grooves of the machining process in the interface area of the neck (Fig. 4). Treated areas (rough areas) show roughened surfaces due to special treatment with acid and sandblasting. Implant 5 showed roughened surface in both areas and no sign for a machined neck part.