## 3 Results
### 3i T3  
The EDX spectrum of the 3i T3 implant is shown in Figure 1c.  
In this case, in addition to the dominating presence of Ti, a weak but significant signal of calcium and phosphorus is observed. In fact, as indicated by the manufacturer, this product bases its interaction with the host tissue on three different characteristics: two topographical and one chemical. The topographical ones will be described shortly, with SEM images (Figure 5). As regarding the chemical characteristic, the presence of calcium phosphate nanocrystals (diameter claimed 0.01-0.1 \(\upmu\)m) deposited on the surface by sol-gel technique is a process commercially known as DCD (discrete crystal deposition). The EDX spectrum therefore confirms the presence of calcium phosphate, a topic that will be taken up in the section on surface analysis using XPS.  
Moving on to SEM observations, in the low magnification backscattered images, the surface appears generally clean, although a greater number of black areas or accumulations can be observed compared to the previous implants, particularly in the collar area. Figure 5b also highlights the different topographical areas of the surface: the threaded area shows signs of sandblasting much more marked than what was observed in the previous cases. The passage area between the rougher body and the collar is visible in Figure 5c. In fact, the two topographical features mentioned are the following: the coronal area is roughened by double acid etching (DAE), the proprietary process that 3i introduced with the Osseotite surface. It produces the only micro-structure, already commented on for previous implants (Figure 5d). The threaded area (Figure 5e) is instead subjected to sandblasting followed by double acid etching, as in the previous cases, but, evidently, with a much more aggressive sandblasting (larger grain sizes, greater pressure). The aim is to provide a double roughness, more contained in the coronal area to reduce the negative effects of any bacterial colonization, and more significantly in the coronal area to maximize the pro-osteogenetic effects induced by the roughness. Both topographical areas also present calcium phosphate nanocrystals, which can be seen in the images at higher magnifications (Figure 5f).  
Figure 4: SEM images of the Prama implant. Low magnification images in backscattered mode of the implant apex (**a**) 55\(\times\), body (**b**) 55\(\times\), and of the implant collar (**c**) 53\(\times\) show that the surface is very clean and free from significant contamination. All the following images are obtained by conventional methods (secondary electrons): (**d**) 200\(\times\) area of passage between the roughened part of the implant body and the collar; (**e**) 1K\(\times\) the collar area at greater magnification; (**f**) 1K\(\times\) the roughened surface of the implant body observed at low magnifications shows the typical plastic deformation from sandblasting.  
The different roughnesses are very well reflected in the three-dimensional processing (Figure 3) and in the roughness data obtained and shown in Table 2.  
The remarkable effect is evident, and can also be appreciated vertically, induced by heavy sandblasting which created very large craters. The double acid etching does not affect the vertical values as much as the contact area.