## 3 Results  
### Statistical Analysis  
The statistical analysis, carried out with the paired Student's \(t\)-test, showed statistically significant differences between the experimental times (before T0 and after T1; manual and ultrasonic scaling) for scaling procedures (see the results reported in Table 2).  
For all the examined groups G1, G2 and G3 (i.e., type of root scaling procedure), statistically significant differences in surface regularity and the presence of instrumentation signs were found between time 0 and time 1 (\(p<0.05\)) within each group, with mean values close to zero (i.e., regular root surface and without the loss of substance and signs of instrumentation) at T0 and close to 1 (i.e., regular root surface with isolated instrumentation marks) at T1. In all cases, therefore, the instrumentation with curette, ultrasonic scaling with conventional and diamond tip altered the texture of the root surfaces examined. On the other hand, the comparison performed as a control test by means of unpaired \(t\)-test of the means of the scores at time 0 (i.e., before scaling) between the three groups did not show significance (\(p>0.05\)).  
Regarding the relative comparison between the groups at T1 (i.e., after scaling), no statistical significance (at the chosen level of 0.05) was highlighted by unpaired \(t\)-test neither between the group treated with the curette (G1) and the one treated with the ultrasonic steel tip (G2), \(p=0.068>0.05\), nor between G1 and the group treated with the ultrasonic diamond tip (G3), \(p=0.057>0.05\), nor between G2 and G3, \(p=0.44>0.05\). However, the  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**A** & **B** & **Mean(A)** & **Mean(B)** & **T** & **df** & \(p\) \\ \hline \multicolumn{8}{c}{Before scaling (T0)} \\ \hline G1 & G2 & 0.27 & 0.23 & 0.29 & 58 & \(3.85\times 10^{-1}\) \\ G1 & G3 & 0.27 & 0.23 & 0.29 & 58 & \(3.85\times 10^{-1}\) \\ G2 & G3 & 0.23 & 0.23 & 0.00 & 58 & \(5.00\times 10^{-1}\) \\ \hline \multicolumn{8}{c}{Before and after scaling} \\ \hline G1 (T0) & G1 (T1) & 0.27 & 1.30 & \(-6.10\) & 29 & \(6.06\times 10^{-7}\) \\ G2 (T0) & G2 (T1) & 0.23 & 1.00 & \(-4.49\) & 29 & \(5.22\times 10^{-5}\) \\ G3 (T0) & G3 (T1) & 0.23 & 0.97 & \(-3.83\) & 29 & \(3.15\times 10^{-4}\) \\ \hline \multicolumn{8}{c}{After scaling (T1)} \\ \hline G1 & G2 & 1.30 & 1.00 & 1.51 & 56 & \(6.82\times 10^{-2}\) \\ G1 & G3 & 1.30 & 0.97 & 1.61 & 55 & \(5.65\times 10^{-2}\) \\ G2 & G3 & 1.00 & 0.97 & 0.15 & 58 & \(4.4\times 10^{-1}\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Student’s \(t\)-test performed for the experimental groups G1, G2 and G3 before (T0) and after (T1) scaling treatments. A and B represent the analysed groups (G1, G2 or G3) where T is the \(t\)-value, df is the degrees of freedom and \(p\) is the \(p\)-value.  
\(p\)-values for the group treated with the curette (G1) with respect to the groups treated with ultrasonic tips (G2 and G3) are very close to 0.05 due the higher mean score of G1.  
The results of the statistical analysis on the data collected after the teeth polishing treatment (T2) with the three different polishing pastes (groups GI, GII and GIII) are reported in Table 3. The data are grouped by type of scaling procedure (manual curette, US steel tip and US diamond tip). All the groups showed mean scores <2, evidencing that the polishing treatments produce smoother surfaces on average. The unpaired \(t\)-test did not evidence statistically significative differences (at the chosen level of 0.05) between the use of Ultrapro Tx cool mint medium(r) (group GI), Stomyprox media(r) (group GII) and Nupro medium orange(r) (group GIII). Polishing with Stomyprox media(r) produced the smoothest surface on average (lower mean score) independently on the employed scaling procedure, even if it was not statistically significant in terms of mean scores with respect to the other pastes at the chosen level of 0.05.