## 3 Results
### Scanning Electron Microscope and EDX Analysis  
The results of the SEM are displayed in Figure 1. Figure 1a (control group) shows a large number of big crater-like porosities (red arrow). The porosities are surrounded by structures that tend to be thin and irregular. In Figure 1b (fluoride group), only a few are of a shallow porosity and are surrounded by a thick, white circular structure (red arrow). In Figure 1c (non-fluoride group), several shallow pores are seen with an irregularly thick structure surrounding them (red arrow).  
Figure 2 and Tables 3-5 show the results of EDX analysis of the enamel surface after debonding the showed amount of minerals in each group. It showed that in the control group, the amount of phosphorous was lower than in the other two groups.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Group** & **n** & **1** & **2** & **3** & **4** & **5** & \(p\) \\ \hline
1 & 9 & 0 & 1 & 3 & 4 & 1 & 0.998 \\  & & & (11.1\%) & (33.3\%) & (44.4\%) & (11.1\%) & \\
2 & 9 & 0 & 0 & 4 & 5 & 0 & \\  & & & & (44.4\%) & (55.5\%) & & \\
3 & 9 & 0 & 1 & 3 & 4 & 1 & \\  & & & (11.1\%) & (33.3\%) & (44.4\%) & (11.1\%) & \\ \hline \end{tabular} Group 1 = control group; group 2 = fluoride group (CPP-ACFP); group 3 = non-fluoride group (CPP-ACP).  
\end{table}
Table 2: Frequency distribution of the ARI in all groups and Kruskal–Wallis test results.  
Figure 1: Scanning electron microscope examination of enamel surface after bracket debonding using 10,000\(\times\) magnification. (**a**) Control group; (**b**) fluoride group (CPP-ACFP); (**c**) non-fluoride group (CPP-ACP). Red arrow outlined the characteristic of surface morphology.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element** & **Element** & **Element Name** & \
\begin{tabular}{c} **Atomic** \\ **Concentration** \\ \end{tabular} &
\begin{tabular}{c} **Weight** \\ **Concentration** \\ \end{tabular} \\ \hline
8 & O & Oxygen & 36.23 & 32.03 \\ \hline
6 & C & Carbon & 44.02 & 29.22 \\ \hline
20 & Ca & Calcium & 10.64 & 23.57 \\ \hline
15 & P & Phosphorus & 6.87 & 11.77 \\ \hline
14 & Si & Silicon & 1.87 & 2.90 \\ \hline
11 & Na & Sodium & 0.28 & 0.35 \\ \hline
17 & Cl & Chlorine & 0.08 & 0.16 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Elements analysis for EDX results of group 3.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element** & **Element** & **Element Name** & \
\begin{tabular}{c} **Atomic** \\ **Concentration** \\ \end{tabular} &
\begin{tabular}{c} **Weight** \\ **Concentration** \\ \end{tabular} \\ \hline
8 & O & Oxygen & 40.32 & 32.75 \\ \hline
20 & Ca & Calcium & 14.59 & 29.69 \\ \hline
6 & C & Carbon & 24.65 & 15.03 \\ \hline
15 & P & Phosphorus & 8.43 & 13.26 \\ \hline
7 & N & Nitrogen & 10.92 & 7.77 \\ \hline
14 & Si & Silicon & 0.56 & 0.80 \\ \hline
11 & Na & Sodium & 0.40 & 0.47 \\ \hline
17 & Cl & Chlorine & 0.13 & 0.23 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Elements analysis for EDX results of group 1.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element** & **Element** & **Element Name** & \
\begin{tabular}{c} **Atomic** \\ **Concentration** \\ \end{tabular} &
\begin{tabular}{c} **Weight** \\ **Concentration** \\ \end{tabular} \\ \hline
8 & O & Oxygen & 40.32 & 32.75 \\ \hline
20 & Ca & Calcium & 14.59 & 29.69 \\ \hline
6 & C & Carbon & 24.65 & 15.03 \\ \hline
15 & P & Phosphorus & 8.43 & 13.26 \\ \hline
7 & N & Nitrogen & 10.92 & 7.77 \\ \hline
14 & Si & Silicon & 0.56 & 0.80 \\ \hline
11 & Na & Sodium & 0.40 & 0.47 \\ \hline
17 & Cl & Chlorine & 0.13 & 0.23 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Elements analysis for EDX results of group 1.  
Figure 2: EDX analysis of enamel surface after bracket debonding. (**a**) Control group; (**b**) fluoride group (CPP-ACFP); (**c**) non-fluoride group (CPP-ACP).