## 3 Results
### SEM Evaluation  
The morphological analysis was performed by scanning electron microscopy in high vacuum (signal of secondary electrons) and at \(50\times\) magnification of the replicas and, after scaling some alterations of the root surface were revealed. Conversely, before scaling, examination of the untreated surfaces revealed the widespread presence of smear layers and debris in the absence of visible signs of instrumentation (an example is reported in Figure 1a). The instrumentation with the ultrasonic steel tip produced a relatively smooth and homogeneous surface, which is more regular than that produced by manual instrumentation, with the absence of deposits and isolated signs produced by the instrumentation. Figure 1b shows, as an example of this type of observation, a replica surface of about 2.5 \(\times\) 2.0 \(\upmu\)m\({}^{2}\) with the cited instrumentation signs visible in the lower part, extended up to about 1.2 \(\upmu\)m here, and a smooth and homogeneous surface in the upper part. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**A** & **B** & **Mean(A)** & **Mean(B)** & **T** & **df** & \(p\) \\ \hline \multicolumn{8}{c}{Manual curette} \\ \hline GI & GII & 1.7 & 1.4 & 1.34 & 18 & 9.82 \(\times\) 10\({}^{-2}\) \\ GI & GIII & 1.7 & 1.6 & 0.45 & 18 & 3.30 \(\times\) 10\({}^{-1}\) \\ GII & GIII & 1.4 & 1.6 & \(-\)0.87 & 18 & 1.99 \(\times\) 10\({}^{-1}\) \\ \hline \multicolumn{8}{c}{US steel tip} \\ \hline GI & GII & 1.8 & 1.5 & 1.41 & 17 & 8.89 \(\times\) 10\({}^{-2}\) \\ GI & GIII & 1.8 & 1.8 & 0.00 & 18 & 5.00 \(\times\) 10\({}^{-1}\) \\ GII & GIII & 1.5 & 1.8 & \(-\)1.41 & 17 & 8.89 \(\times\) 10\({}^{-2}\) \\ \hline \multicolumn{8}{c}{US diamond tip} \\ \hline GI & GII & 1.7 & 1.5 & 0.88 & 18 & 1.94 \(\times\) 10\({}^{-1}\) \\ GI & GIII & 1.7 & 1.7 & 0.00 & 18 & 5.00 \(\times\) 10\({}^{-1}\) \\ GII & GIII & 1.5 & 1.7 & \(-\)0.88 & 18 & 1.94 \(\times\) 10\({}^{-1}\) \\ \hline \end{tabular}
\end{table} 
Table 3: Student’s \(t\)-test performed for the experimental groups GI, GII and GIII after the polishing treatments (T2). A and B represent the analysed groups (GI, GII or GIII), T is the \(t\)-value, df is the degrees of freedom, and \(p\) is the \(p\)-value. In the samples treated with curettes, the signs of the blade are clear, resulting in a more irregular surface macro-texture compared to that produced with the ultrasonic instrumentation with a steel tip and with ultrasound with a diamond tip. The SEM micrograph of Figure 1c is reported as an example to shows these surface features caused by the use of curettes, which for the full height of the image (about 2 \(\upmu\)m). Figure 1: SEM pictures of replicas of untreated (**(a)**: 50\(\times\)) and scaled (**(b–d)**: 50\(\times\); **(e)**: 200\(\times\)) root surfaces. (**a**) Untreated surface showing the presence of smear layers and debris in the absence of visible signs of instrumentation. (**b**) Replica of root surface treated with ultrasonic conventional tips showing a relatively smooth and homogeneous surface, with the absence of deposits and isolated signs produced by the instrumentation. (**c**) Replicas of curette treated teeth showing widespread signs of the instrumentation. (**d**) Replicas of samples treated with ultrasonic diamond tip showing a relatively homogeneous surface with localized signs produced by the instrumentation. (**e**) SEM pictures at 200\(\times\) of sample treated with ultrasonic diamond tip showing an isolated area of loss of substance. Samples treated with a diamond ultrasonic tip showed, at a higher magnification, a relatively homogeneous surface with localized signs produced by the instrumentation and isolated areas of loss of substance. The upper part of Figure 1d provides an example of these features acquired at 50\(\times\) magnification, whereas in Figure 1e an isolated area of loss of substance produced by the diamond ultrasonic tip is well resolved and up to about 150 \(\upmu\)m wide and 350 \(\upmu\)m long; the measurements are acquired at 200\(\times\) magnification.