## 4 Discussion  
The aim of the study was to understand the pattern and quantification of the release of fluoride ions from the Wave and Freedom materials placed in various environments as well as to assess the impact of pH on this process. In the acidic environment of pH 4.5 and 5.5, the higher cumulative release of fluoride from the composite material (W) can be observed, respectively, in artificial saliva solutions without the addition of Ca\({}^{2+}\) ions at pH 4.5 (5.048 \(\pm\) 1.010 \(\upmu\)g F/mm\({}^{2}\)), pH 5.5 (6.835 \(\pm\) 1.130 \(\upmu\)g F/mm\({}^{2}\)) and compomer (F) at pH 4.5 (31.195 \(\pm\) 10.461 \(\upmu\)g F/mm\({}^{2}\)) and pH 5.5 (23.200 \(\pm\) 1.107 \(\upmu\)g F/mm\({}^{2}\)), respectively, in which the emission of fluoride ions from the compomer material (F) was significantly larger. During the release of fluoride from composite materials, an initial strong increase in fluoride ions is noticeable in the release medium, i.e., \"burst effect\" [37]. For the Wave \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & **AS** & **AS** & **AS** & **AS** & **AS** & **AS + Ca\({}^{2+}\)** & **AS + Ca\({}^{2+}\)** & **Deionized** & **0.9\% NaCl** \\
**Time** & **pH 4.5** & **pH 5.5** & **pH 6.0** & **pH 7.0** & **pH 7.5** & **pH 4.5** & **pH 5.5** & **Hg 0** & **(9)** \\
**(Hours)** & **(1)** & **(2)** & **(3)** & **(4)** & **(5)** & **(6)** & **(7)** & **(8)** & **(9)** \\  & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** & **(\(\upmu\)/mm\({}^{2}\))** \\ \hline
**1** & 5.7 \(\pm\) 2.5 & 4.9 \(\pm\) 0.4 & 0.7 \(\pm\) 0.1 & 1.1 \(\pm\) 0.3 & 1.7 \(\pm\) 0.2 & 1.6 \(\pm\) 0.3 & 0.9 \(\pm\) 0.02 & 0.4 \(\pm\) 0.1 & 0.3 \(\pm\) 0.01 \\
**3** & 13.8 \(\pm\) 5.1 & 9.4 \(\pm\) 0.6 & 1.7 \(\pm\) 0.2 & 1.9 \(\pm\) 0.3 & 3.8 \(\pm\) 0.3 & 7.5 \(\pm\) 1.0 & 2.6 \(\pm\) 0.1 & 1.3 \(\pm\) 0.1 & 0.6 \(\pm\) 0.1 \\
**24** & 20.8 \(\pm\) 8.0 & 13.8 \(\pm\) 0.7 & 2.6 \(\pm\) 0.4 & 2.7 \(\pm\) 0.4 & 6.0 \(\pm\) 0.5 & 10.2 \(\pm\) 1.8 & 4.2 \(\pm\) 0.1 & 2.7 \(\pm\) 0.4 & 1.2 \(\pm\) 0.2 \\
**48** & 24.9 \(\pm\) 9.4 & 16.3 \(\pm\) 0.8 & 3.5 \(\pm\) 0.7 & 3.5 \(\pm\) 0.4 & 7.0 \(\pm\) 0.7 & 15.2 \(\pm\) 2.6 & 5.8 \(\pm\) 0.3 & 3.8 \(\pm\) 0.6 & 1.9 \(\pm\) 0.5 \\
**72** & 28.0 \(\pm\) 9.9 & 19.0 \(\pm\) 1.0 & 4.1 \(\pm\) 1.1 & 3.8 \(\pm\) 0.4 & 8.7 \(\pm\) 1.0 & 18.8 \(\pm\) 3.3 & 7.3 \(\pm\) 0.3 & 4.6 \(\pm\) 0.8 & 2.3 \(\pm\) 0.5 \\
**168** & 31.2 \(\pm\) 10.5 & 23.2 \(\pm\) 1.1 & 4.6 \(\pm\) 1.1 & 4.5 \(\pm\) 0.6 & 10.2 \(\pm\) 1.0 & 20.7 \(\pm\) 3.4 & 8.2 \(\pm\) 0.4 & 6.2 \(\pm\) 1.4 & 3.7 \(\pm\) 1.1 \\ \hline
**Correlation** & & & & & & & & & & \\
**(Pearson test)** & \(r=0.957\); & & & & & & & & & & \\ \(p=0.003\) & \(r=0.979\); & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Cumulated release of fluoride ions (\(\upmu\)/mm\({}^{2}\)) from compomer Freedom (F) into nine environments differing in composition of the solution and pH. Six samples were prepared for each solution. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & **AS** & **AS** & **AS** & **AS** & **AS** & **AS + Ca\({}^{2+}\)** & **AS + Ca\({}^{2+}\)** & **Deionized** & **0.9\% NaCl** \\
**Time** & **pH 4.5** & **pH 5.5** & **pH 6.0** & **pH 7.0** & **pH 7.5** & **pH 4.5** & **pH 5.5** & **Hg\({}^{2}\)** & **(9)** \\
**(Hours)** & **(1)** & **(2)** & **(3)** & **(4)** & **(5)** & **(6)** & **(7)** & **(8)** & **(9)** \\
**(\(\upmu\)/mm\({}^{2}\))** & **(\(\up  
material, the highest release kinetics occurred on the third day of the experiment in solutions with a pH of 4.5 and 5.5. On the other hand, in the case of Freedom, the release of fluorides occurred at pH 4.5 and 5.5 on the first day of the experiment. The research shows that there is a dependence of the pH of artificial saliva on the amount of released fluoride ions.