## 3 Results
### Quality Assessment Outcomes  
According to CHSRI, six studies [15; 24; 35; 47; 48] mentioned choosing their patients randomly, and none mentioned blinding their participants or assessors. Eight studies [15; 20; 47; 55; 58; 63; 65; 68] mentioned the withdrawal/dropout of their participants. Only 24 studies [14; 15; 17; 19; 20; 22; 23; 26; 22; 23; 26; 27; 28; 29; 30; 31; 32; 33; 36; 38; 39; 41; 43; 51; 52; 54; 55; 56; 57; 59; 61; 67] repeated the measurement of their variables, likewise 6 studies [30; 41; 42; 46; 47; 62] carried out sample size estimation and 35 studies [14; 15; 17; 19; 20; 21; 23; 24; 25; 26; 27; 28; 29; 31; 32; 33; 35; 36; 38; 41; 43; 45; 47; 52; 55; 59; 61; 64; 65; 66; 67; 68] tested their examiner reliability[PERSON] Fifty-two studies [14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 38; 41; 42; 43; 44; 45; 46; 47; 58; 59; 61; 62; 63; 64; 65; 66; 67; 68] clerally mentioned their inclusion and exclusion criteria. All the included studies clearly reported their outcomes. Through this assessment, 43 studies were categorized as [PERSON]moderate\" risk of bias, three studies were \"low\" risk of bias, and 6 studies were \"high\" risk of bias (Table 6). In accordance with NOS for quality assessment, the included studies scored in the range from 5 to 9 points, with a mean score of 6.84[PERSON] Three studies carried a \"low\" risk of bias, while 44 studies and 5 studies showed moderate and high risk of bias, respectively (Table 7). [PERSON]begin{table} \begin{tabular}{c c c c c c} \hline \hline
**No.** & **Author ID Year** & **Selection** & **Comparability** & **Exposure** & **Quality** \\ \hline
1. & [PERSON] 1993 & *** & * & * & 6 \\ \hline
2. & [PERSON] 2004 & *** & ** & *** & 9 \\ [PERSON]hline
3. & [PERSON] 2010 & *** & ** & ** & 7 \\ \hline
4. & [PERSON] et al. 2019 & *** & * & ** & 6 \\ \hline
5. & [PERSON] 2014 & ** & * & ** & 5 \\ \hline
6. & [PERSON] 2016 & *** & * & ** & 7 \\ \hline
7. & [PERSON] et al. 2019 & *** & * & ** & 7 \\ [PERSON]hline
8. & [PERSON] 2016 & ** & * & ** & 5 \\ \hline
9. & [PERSON] 2008 & ** & * & ** & 5 \\ \hline
10. & [PERSON] et al. 2015 & *** & ** & 8 \\ \hline
11. & [PERSON] 2013 & *** & ** & ** & 8 \\ \hline
12. & [PERSON] 2012 & *** & * & ** & 8 \\ \hline \hline \end{tabular} 
\end{table}
Table 6: Newcastle-Ottawa scale for quality assessment of included articles (\(n=52\)). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Local Proportion \({}^{\alpha}\)** & **\(N\)\({}^{*}\)** & **Range** & \
\begin{tabular}{c} **Mean** \\ **Percentage \({}^{\beta}\)** \\ \end{tabular} &
\begin{tabular}{c} **Standard** \\ **Deviation** \\ \end{tabular} \\ \hline Right central and lateral incisor & 38 & 40-70 & 54.526 & 14.684 \\ Right lateral incisor and canine & 36 & 51-78 & 63.975 & 13.121 \\ Left central and lateral incisor & 38 & 42–69 & 55.024 & 13.072 \\ Left lateral incisor and canine & 36 & 51–78 & 63.975 & 13.121 \\ \hline \hline \end{tabular} \({}^{*}\) Number of articles; [PERSON]alpha}\) geographic-based proportion of anterior teeth from included articles; \({}^{\beta}\) Mean value of dental proportion.  
\end{table} 
Table 5: Mean values of observed proportion from included articles (\(n=38\)). \begin{table}
\begin{tabular}{c c c c c c} \hline
**No. ** & **Author ID Year** & **Selection** & **Comparability** & **Exposure** & **Quality** \\ \hline
13. & [PERSON] 2016 & *** & * & ** & 7 \\ [PERSON]hline
14. & [PERSON] 2013 & *** & * & ** & 6 \\ \hline
15. & [PERSON] 2014 & ** & * & ** & 5 \\ \hline
16. & [PERSON] 2016 & *** & * & ** & 7 \\ \hline
17. & [PERSON] 2014 & *** & * & ** & 6 \\ \hline
18. & [PERSON] 2017 & *** & * & ** & 6 \\ [PERSON]hline
19. & [PERSON] 2017 & *** & ** & ** & 8 \\ \hline
20. & [PERSON] & *** & * & ** & 7 \\ \hline
21. & [PERSON] et al. 2015 & *** & ** & ** & 8 \\ \hline
22. & [PERSON] 2018 & *** & * & ** & 6 \\ \hline
23. & [PERSON] 2017 & *** & * & ** & 6 \\ \hline
24. & [PERSON] et al. 2010 & *** & * & ** & 6 \\ \hline
25. & [PERSON] et al. 2009 & *** & ** & ** & 9 \\ \hline
26.