# An Evaluation of the Demineralizing Effects of Various Acidic Solutions
## 3 Results and Discussion
### VITA Easyshade(r)  
The study groups recorded variables where the \(\Delta\)E values were taken at four time intervals (\(\Delta\)E1, \(\Delta\)E2, \(\Delta\)E3 and \(\Delta\)E4) in six different demineralizing solutions (hydrochloric gel; orthophosphoric acid gel; lactic acid; orthophosphoric acid; and CaCl\({}_{2}\), NaH\({}_{2}\)PO\({}_{4}\) and acetic acid solution). N = 3 measurements were made for each assessment. In the chart below, the \(\Delta\)E values were calculated between two etching cycles. Thereby, \(\Delta\)E1, 2, 3 and 4 represent the color differences between the different measurements (see Table 2). Statistical analysis was performed in order to compare the \(\Delta\)E values obtained for the same demineralizing intervals and in different acidic solutions. For the \(\Delta\)E1, the ANOVA one-way test showed a statistically significant difference (\(p\) = 0.0354) between the formic acid-orthophosphoric acid gel and CaCl\({}_{2}\), NaH\({}_{2}\)PO\({}_{4}\) and acetic acid solution-orthophosphoric acid gel. In \(\Delta\)E2, a statistically significant difference was found (\(p\) = 0.25443) but without differences in the Tukey test. Regarding \(\Delta\)E3, the ANOVA test showed no statistically significant difference (\(p\) = 0.25443) between any of the demineralizing solutions. In \(\Delta\)E4, a statistically significant difference was found (\(p\) = 2.12339 \(\times\) 10\({}^{-9}\)), except for the comparison between the lactic acid-hydrochloric gel; formic acid-orthophosphoric acid solution; and CaCl\({}_{2}\), NaH\({}_{2}\)PO\({}_{4}\) and acetic acid solution-hydrochloric gel. Vita Easyshade(r) readings, shown in Figure 7, show a medium color change after etching the tooth for 30 min and a small difference after 1 h. It is obvious that after 24 h, the \(\Delta\)E3 value is higher. The most outstanding results were obtained for the teeth treated for 96 h with the 37% orthophosphoric acidic solution. This remarkable deviation is explained by the spectrophotometric difference between the enamel and dentine aspects. In the following figure, \(\Delta\)E values represent the difference between the initial situation and that after each etching period. Thus, \(\Delta\)E1 is calculated between the initial state and after a 30 min etching, \(\Delta\)E2 between the initial state and 1 h, \(\Delta\)E3 between the initial state and 24 h and \(\Delta\)E4 between the initial state and 96 h of acidic treatment. \begin{table}
\begin{tabular}{c c} \hline \hline
**AE Values Calculated between Two Etching Cycles** & **Signification** \\ \hline \(\Delta\)E1 & Initial situation–30 min of demineralization \\ \(\Delta\)E2 & 30 min–1 h acid cycle \\ \(\Delta\)E3 & 1 h-24 h of etching \\ \(\Delta\)E4 & 24–96 h of acidic treatment \\ \hline \hline \end{tabular}
\end{table} 
Table 2: \(\Delta\)E values and their signification. The only demineralizing solution that presented a statistically significant difference with \(p\) = 0.02042 for the ANOVA test and no difference for the Tukey test was the orthophosphoric acid gel. The lactic acid and orthophosphoric acid solution showed statistically significant differences for all the time intervals, except for the first two: between the initial state and 30 min, and between the initial state and 60 min. For the hydrochloric gel; formic acid; and CaCl\({}_{2}\), NaH\({}_{2}\)PO\({}_{4}\) and acetic acid solution, the ANOVA one-way test presented statistically significant differences (\(p\) = 7.21066 \(\times\) 10\({}^{-7}\), \(p\) = 5.59125 \(\times\) 10\({}^{-9}\) and \(p\) = 1.03103 \(\times\) 10\({}^{-7}\)) for all the time intervals, except for the first one (between the initial situation and after 30 min). Figure 8 represents the visual changes over time for each acidic solution used in the study. \(\Delta\)E values represent the difference between the initial state and after each etching period. There is a relatively small difference between \(\Delta\)E1 and \(\Delta\)E2 and a remarkable increase in \(\Delta\)E4 for each demineralizing solution.