The surface shape (droplet-like surface), which was observed in the SEM samples, can be caused due to the sintering process in which ceramic powder was melted and then formed. Different particle, immersion, and droplet sizes can also change due to possible reasons like usage of various types and dosages of acid for the etching process and change of exposure time to acid effect. A longer exposure time to etching process could also be responsible for lowering aluminum corundum from sandblasting processes. However, despite a very fine surface microstructure, implant 4 shows the highest amount of aluminum on the outer surface. This could be explained by sandblasting with aluminum-containing corundum particles followed by a shorter etching process. The higher amount of aluminum in implants 1, 4, and 5 might be due to the individual material composition while sintering the material mixture or to corundum particles of the machining and sandblasting process. Implants with aluminum under the detection limit could be caused by a final etching process. Implants 1 and 5 are not advertised with a special etching process. However, implant 4 is supposed to be etched. The etching could have happened before sandblasting, or the acid used was not strong enough to eliminate all aluminum particles.

All implants excluding the Ceralog Monobloc (implant 5) show typical parallel grooves of the machining process in the confocal laser scan and rougher surfaces in the treated areas. Ceralog is the only implant with a rough surface that can also be found in the machined area. Zirconia implants which are treated with a process of sandblasting, etching, and heat treatment are showing a micro-structured surface resulting in a surface roughness in the range of 1.2 μm [22]. In this study, implants 2 and 5 showed roughness values in the range of 1.2 μm. The other implants showed different roughness values. The surface porosity of titanium implants after sandblasting and etching processes is much more rigorous than that of the ceramic implants that were investigated. In this study, implants 2 and 5 can approximately be compared to titanium surface characteristics in the SEM samples. However, implant 5 was not sandblasted and etched because of a special “injection molding technique” and shows a wide distribution of roughness values. A similarity to the surface structure of titanium implants cannot be proven yet.