## 3 Results  
Descriptive statistics for SR and microhardness properties in the eight groups are shown in Table 1.  
The results of the material comparison are shown in Table 2.  
Comparison of materials with respect to SR showed that there is a difference between them (\(p\) < 0.0001; ANOVA test). The results of the multiple comparison (Tukey test) with respect to SR showed that values for Fuji IX are higher on average in comparison to the values for Fuji II irrespective of HA concentration. For Fuji IX, SR also generally increases with the increase of HA concentration. Roughness of Fuji IX 10 wt % HA was statistically higher than the SR of Fuji IX without HA and Fuji IX 5 wt % HA. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **N** & **SR Mean** & **Microhardness Mean** \\ \hline Fuji II0 & 10 & 0.062 & 0.070 \\ Fuji II2 & 10 & 0.069 & 0.078 \\ Fuji II5 & 10 & 0.080 & 0.087 \\ Fuji II10 & 10 & 0.089 & 0.097 \\ Fuji IX0 & 10 & 0.176 & 0.199 \\ Fuji IX2 & 10 & 0.221 & 0.269 \\ Fuji IX5 & 10 & 0.192 & 0.212 \\ Fuji IX10 & 10 & 0.254 & 0.282 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Descriptive statistics for surface roughness (SR) and microhardness. There is difference in microhardness between the groups, too (\(p\) < 0.0001; ANOVA test). The addition of HA to Fuji II is not conclusive. Lowest microhardness is observed for 2 wt % HA, but Tukey test showed that microhardness of Fuji II with 10 wt % HA was significantly higher. In Fuji IX groups, it was observed that increase of HA concentration decreased microhardness. However, only the difference between 10 wt % HA concentration and 2 wt % HA concentration and the difference between 10 wt % HA concentration and group without HA particles added were significant. There was no evidence that microhardness for the group without HA particles and groups with 2 wt % HA and 5 wt % HA differ. The observed SEM images of representative of one specimen surface from each group are shown in Figure 1.  
The SEM images display small glass particles dispersed in the matrix. SEM images of Fuji II, either the group without HA added or experimental groups displayed predominantly smooth, and featureless surfaces (Figure 1, a-d) but cracks or voids were evident on the surfaces of HA added specimens (b-d) in contrast to the group without HA (a). The surfaces of Fuji IX (e-h) appeared relatively rough, demonstrating macro defects on the surfaces. The results for fluoride ion release are shown in Figure 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **Surface Roughness (Ra)** & **Microhardness (VHN)** \\ \hline Fuji II0 & 0.062 & a & 55.2 & ab \\ Fuji II2 & 0.069 & a & 47.5 & bc \\ Fuji II5 & 0.080 & a & 53.0 & b \\ Fuji II10 & 0.089 & a & 61.5 & a \\ Fuji IX0 & 0.176 & b & 50.6 & b \\ Fuji IX2 & 0.221 & bc & 48.9 & b \\ Fuji IX5 & 0.192 & b & 47.2 & bc \\ Fuji IX10 & 0.254 & c & 40.7 & c \\ \hline \(p\) * & \textless{}0.0001 & & \textless{}0.0001 & \\ \hline \hline \end{tabular}  
* \(p\)-value for ANOVA test; a, b, c—materials with the same letter are not significantly different (Tukey test).  
\end{table} 
Table 2: Results of the ANOVA test for Fuji II and Fuji IX. Figure 1: Representative SEM photomicrographs (\(\times\)100 magnification) of a Fuji II (first row): Fuji II (without HA particles), Fuji II 2 wt % HA, Fuji II 5 wt % HA, Fuji II 10 wt % HA respectively; and Fuji IX (2 nd row): Fuji IX (without HA particles), Fuji IX 2 wt % HA, Fuji IX 5 wt % HA, Fuji IX 10 wt % HA respectively. The results for Fuji IX were significantly higher than the results for Fuji II (\(p\) < 0.001). In terms of time, it can be noticed that the concentration of the released fluoride ions rate significantly decreased with time (\(p\) < 0.001). This decrease was significantly different for the two materials (\(p\) < 0.001). When observing the effects of adding HA to the materials, the fluoride release was different when compared to the group without HA added. This effect was, however, neither consistent nor clearly dependent on concentration.