# A Literature Review on the Uncommon Use of Extraoral Periapical Radiography
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Ref.** & **First Author** & **Year** & \begin{tabular}{c} **Reason for** \\ **Taking Radiographs** \\ \end{tabular} & \begin{tabular}{c} **No.** \\ **of Patients** \\ \end{tabular} & \begin{tabular}{c} **Age of** \\ **Patients (y)** \\ \end{tabular} & \
\begin{tabular}{c} **No.** \\ **of Images** \\ \end{tabular} &
\begin{tabular}{c} **Type** \\ **of Teeth** \\ \end{tabular} & **Comparison with IOPA** \\ \hline
[27] & [PERSON] & 2020 & Research &? & 13–25 &
\begin{tabular}{c} 60 IOTA \\ (paralleling) \\ and 60 EOPA \\ of same teeth \\ \end{tabular} & 34, 44 & WL: EOPA \(<\) IOPA by 0.25 mm (n.s.) \\ \hline
[28] & [PERSON] & 2018 & \begin{tabular}{c} All \\ indications \\ \end{tabular} & 45 & 18-70 & \
\begin{tabular}{c} 45 IOPA \\ (bisecting angle) and 45 EOPA of \\ same teeth \\ \end{tabular} & Posteriors &
\begin{tabular}{c} Density and contrast: \\ EOPA \(=\) IOPA (n.s.); \\ sharpness, magnification, \\ distortion, anatomical \\ accuracy, and radiographic \\ coverage: EOPA \(<\) IOPA \\ (\(p<\) 0.05) \\ \end{tabular} \\ \hline
[29] & [PERSON] & 2017 & \begin{tabular}{c} Check \\ tooth length \\ \end{tabular} & NA & NA & \
\begin{tabular}{c} 16 IOTA (?) \\ and 16 EOPA \\ of same teeth \\ \end{tabular} & Posteriors &
\begin{tabular}{c} Tooth length: \\ EOPA \(=\) IOPA (n.s.) \\ \end{tabular} \\ \hline
[30] & [PERSON] & 2016 & \begin{tabular}{c} Check \\ root length \\ \end{tabular} & NA & NA & \
\begin{tabular}{c} 16 IOTA (?) \\ and 8 EOPA \\ of same teeth \\ \end{tabular} & Posteriors &
\begin{tabular}{c} Root length: \\ EOPA \(=\) IOPA (n.s.) \\ \end{tabular} \\ \hline
[31] & [PERSON] & 2016 & Check WL & 2 & 28 & 4 EOPA & 16, 36 & NA (check WL) \\ \hline
[32] & [PERSON] & 2015 & Unspecified & 30 & 3-8 & \
\begin{tabular}{c} 30 IOTA \\ (bisecting angle) and 30 EOPA of \\ same teeth \\ \end{tabular} & Posteriors &
\begin{tabular}{c} Blurring and overlapping of \\ structures: EOPA \(>\) IOPA by 60\% and 37\%, respectively \\ (no statistical test) \\ \end{tabular} \\ \hline
[35] & [PERSON] & 2014 & Research & 20 & 10-35 & 20 EOPA & Posteriors &
\begin{tabular}{c} NA (checked entire \\ teeth visualization) \\ \end{tabular} \\ \hline
[36] & [PERSON] & 2013 & \
\begin{tabular}{c} All \\ indications \\ \end{tabular} & 40 &
\begin{tabular}{c} Children \\ and adults \\ \end{tabular} & 40 EOPA & Posteriors & NA \\ \hline
[37] & [PERSON] & 2013 & Research & 80 & Adults & 80 EOPA &
\begin{tabular}{c} Mandibular \\ premolars \\ \end{tabular} & NA (check WL) \\ \hline
[39] & [PERSON] & 2012 &
\begin{tabular}{c} Optimize \\ technique \\ \end{tabular} & NA & NA &? & Posteriors & NA \\ \hline
[40] & [PERSON] & 2011 & Research &? &? &? & Posteriors & NA \\ \hline
[41] & [PERSON] & 2011 &
\begin{tabular}{c} All \\ indications \\ \end{tabular} & 3 & 7–35 & 3 EOPA & Posteriors & NA \\ \hline
[42] & [PERSON] & 2007 & Research & 12 & 26–65 & 12 EOPA & Posteriors & NA \\ \hline
[17] & [PERSON] & 2003 & Check WL & 2 & 8–16 & 2 EOPA & Posteriors & NA \\ \hline \hline \end{tabular}
\end{table} 
Table 2: General study design of the 14 original articles on EOPA. so it solely relies on the patient's hand to hold it steadily in the correct position during the entire radiographic procedure. Hence, it may be difficult for some patients to keep the holder in the correct position over a prolonged period of time. Finally, it was found that the exposure factors (kV, mA, s) reported in the papers were diverse (Table 3). Digital imaging with an intraoral sensor (IO sensor) was more frequently involved than traditional film, whereas no paper used a phosphor plate. The papers reviewed in this report clearly showed diverse settings in terms of both patient positioning and radiographic equipment settings. This heterogeneity poses challenges for standardization and comparisons across studies, highlighting the need for more uniform protocols. Figure 4: Technique used in EOPA in 14 papers. Angulations indicated for maxillary (black) and mandibular (red) EOPA are indicated.