## 3 Results
### Tribological Characterization  
Activa(tm) was able to better reduce the vibration response with a consequent structure resistance, while Ketac(tm) showed an opposite behavior which is presented in the graphs in Figure 10.  
Figure 9 presents different parts of the scratch test for the Filtek Supreme(tm) specimen where it is possible to observe the middle part (Figure 10a) and the final part (Figure 10b). It is equally possible to observe the region where the wear profiles were taken (Figure 10a). Figure 11 shows the wear profiles for the different specimens, before and after thermocycling, showing the evolution of the wear depth and worn area with the transversal distance at a fixed sliding distance of 8 mm (16 N). The depth of the wear track and the worn area are smaller for the Activa(tm) specimen with values of 98.04 um and 1.11 \(\times\) 10\({}^{-4}\) um\({}^{2}\), respectively. For the Filtek Supreme(tm) specimen, these values increase to 108.32 um and 1.35 \(\times\) 10\({}^{-4}\) um\({}^{2}\), respectively. Finally, for the Ketac(tm) specimen, the values increase signifi \begin{table}
\begin{tabular}{c c} \hline \hline
**Specimens** & **tan \(\delta\)** \\ \hline
**Activa(tm)** & 0.06 \\ \hline
**Filtek(tm)** & 0.044 \\ \hline
**Ketac(tm)** & 0.02 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: tan \(\delta\)—ratio of the loss modulus to storage modulus for the different specimens (37 \(\pm\) 2 \({}^{\circ}\)C). Figure 9: Dynamic elastic modulus for the different materials before (25 \(\pm\) 2 \({}^{\circ}\)C and 37 \(\pm\) 2 \({}^{\circ}\)C) and after thermocycling (37 \(\pm\) 2 \({}^{\circ}\)C). cantly to 124.71 \(\upmu\)m and 2.68 \(\times\) 10\({}^{-4}\)\(\upmu\)m\({}^{2}\), respectively. For Activa(tm) and Filek Supreme(tm), the results for the worn area and maximum depth of the wear track do not vary much before and after being subjected to thermocycling. In the case of Ketac(tm) the values obtained for the maximum depth of the wear track before and after thermocycling are 124.71 \(\upmu\)m and 203.42 \(\upmu\)m, respectively, and the values for the worn area before and after thermocycling are 2.68 \(\times\) 10\({}^{-4}\)\(\upmu\)m\({}^{2}\) to 3.90 \(\times\) 10\({}^{-4}\)\(\upmu\)m\({}^{2}\), respectively. Figure 10: Optical micrographs showing different parts of the longitudinal wear track for the Filek Supreme(tm) specimen after thermocycling: (**a**) middle of the scratch and (**b**) end of the scratch. Figure 11: Wear profiles for the different specimens, before and after thermocycling, showing the evolution of the wear depth with the transversal distance. These profiles were taken at 8 mm sliding distance and with an applied load of approximately 16 N: (**a**) ActivaTM; (**b**) Filek SupremeTM; (**c**) KetacTM. Figure 12 represents the evolution of the normal force and tangential force with the sliding time. The sliding time is the time it takes the indenter to travel the 10 mm sliding distance. It can be observed that the normal force increases progressively and linearly until reaching approximately 20 N and that the tangential force responds to this force depending on the specimen under analysis. In order to assess the value of the COF for the different specimens, it is necessary to represent the tangential force as a function of the normal force and calculate the slope of the adjusted trend line, as exemplified in Figure 13 for ActivaTM. Table 3 summarizes the results of the COF as well as the worn area and the maximum depth of the wear track for the different specimens, before and after thermocycling. Regarding the COF, Filek SupremeTM present lower results than those of the ActivaTM and KetacTM. Except for Filek SupremeTM, the COF increased with thermocycling. Figure 12: Output from the scratch test, showing the evolution of normal load (blue color) and tangential load (orange color) with sliding time (this test was performed for ActivaTM before being subject to thermocycling).