## 2 Materials and Methods
### Evaluation of Topography and Surface Roughness  
Topography and surface roughness of the implants being studied were assessed by scanning electron microscopy (SEM) in normal mode and with a diffuse retro electron detector (BSE = back scattered electrons). The observations were made using an EVO MA 10 instrument (ZEISS). The main parameters of the analysis (electron high tension = EHT, working distance = WD, magnification = Mag, type of detector = Signal A) are shown directly in the photographs. SEM analysis carried out using a detector capable of detecting backscattered electrons (BSE) provides indications on the presence of heterogeneous elements with respect to those that make up the sample under examination due to the fact that backscattering efficiency is a function of the atomic number and any contaminants of different chemical nature are easily visualized thanks to the different shades of gray that they produce. The application of this method of observation is therefore of considerable use in evaluating the effectiveness of material cleaning protocols. In light of this, low-magnification images have been taken for each sample, along with the detector for backscattered electrons, in order to have an overview and the qualitative chemical information of the implant surfaces. The images taken with this mode have Signal A = CZ BSD written on the white stripe at the bottom, while those done with the normal detector have Signal A = SE1 written in the same location. Due to its non-metallic nature, NobelPearl tapered implant was subjected to metallization with 99.99 gold (Agar Sputter Coater, AGAR SCIENTIFIC LTD) in order to create electron conductivity and, therefore, allowed for the use of this analytical technique. For the other implants analyzed, no preparation was necessary. Before each SEM observation, an EDX (energy dispersive X-ray analysis) spectrum of the implant under examination was obtained to confirm the chemical nature of the material used for its construction. For this analysis, an Atzec EDX microprobe, produced by Oxford, was used. Surface roughness was quantitatively assessed using the stereo-SEM method (SSEM) with dedicated software to convert traditional SEM images into three-dimensional data (Mex 6.1, Alicona Imaging). In particular, using the principles of stereoscopic vision, a representative image of the topography was obtained from two slightly different viewing angles, that is, with the specimen holder in a horizontal position and with a slight inclination (tilt angle). The software combined the two images and collected three-dimensional information, allowing the user to extract the various roughness parameters defined in the literature. In particular, according to the procedure adopted, a tilt angle of 5 degrees was used, images were obtained at 2000\(\times\), and the analyzed area was \(90\times 120\)\(\upmu\)m, the geometric area evaluated was therefore \(90\times 120=10\),800 \(\upmu\)m\({}^{2}\). The following area roughness parameters were calculated, according to ISO25178 parameters:  
Sa: average height deviation of the selected area; it expresses, as an absolute value, the difference in height of each point compared to the arithmetical mean of the surface;  
Sz: maximum height of the selected area; it is defined as the sum of the greatest peak height value and the greatest pit depth value within the defined area. Sdr: relationship between developed area and geometric area, is expressed as the percentage of the definition area's additional surface area contributed by the texture as compared to the planar definition area. The Sdr of a completely level surface is 0. Sa, Sz, and Sdr are the equivalent of the roughness parameters Ra, Rz, and Rdr when recorded on a 3-dimensional surface. They are modern parameters derived from processing of data within an area and not along a line.