# Optimization of Image Capture Distance for Facial Thermograms in Dentistry
## 3 Results
### Correlations of the Mean Overall Temperature  
The Spearman's Rho correlation statistics (Table 6) revealed that the mean overall temperature correlated to the presence of personal effects such as spectacles [r\({}_{\rm s}\) (1348) = 0.070, \(p\) = 0.011], scars/headphones/cap/hat/shawls [r\({}_{\rm s}\) (1348) = -0.084, \(p\) = 0.002], and protective wear for neck protection [r\({}_{\rm s}\) (1348) = -0.099, \(p\) < 0.001]. The mean overall temperature was positively influenced by having undergone dental treatments [r\({}_{\rm s}\) (1348) = 0.079, \(p\) = 0.004] and negatively correlated to having undergone physiotherapy sessions [r\({}_{\rm s}\) (1348) = -0.071, \(p\) = 0.009] in the last 24 h, respectively. The mean overall temperature was also positively correlated to interdental cleaning [r\({}_{\rm s}\) (1348) = 0.095, \(p\) < 0.001] and hairdryer use [r\({}_{\rm s}\) (1348) = 0.082, \(p\) = 0.003]. No demographic or other influencing factors had any correlation with the mean overall temperature in the thermograms (Table 6). \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Views**} & \multicolumn{3}{c}{**Temperature**} & \multicolumn{3}{c}{**Measured Temperatures at Different Shooting Distances for the Different Profiles**} & \multicolumn{3}{c}{**Temperature Differences between Shooting**} \\  & **(in °)C** & & & **(in °)C** & & & **Distances (in °)C** & & & **Distances (in °)C** \\ \hline \multicolumn{1}{c}{} & \multicolumn{3}{c}{15 cm} & \multicolumn{3}{c}{30 cm} & \multicolumn{3}{c}{50 cm} & \multicolumn{3}{c}{15-30 cm} & \multicolumn{3}{c}{30-50 cm} & \multicolumn{3}{c}{15-50 cm} \\ \hline Front & N & Mean & SD (SE) & Mean & SD (SE) & Mean & SD (SE) & Mean (SE) & Mean (SE) & Mean (SE) \\ \hline Overall & 150 & 31.80 & 1.43 (0.12) & 29.62 & 0.73 (0.06) & 27.25 & 0.74 (0.06) & 2.19 (0.12) & 2.36 (0.12) & 4.55 (0.12) \\ \hline ROI & 150 & 32.93 & 1.05 (0.09) & 34.07 & 0.86 (0.07) & 33.62 & 1.06 (0.09) & \(-\)1.14 (0.11) & 0.45 (0.11) & \(-\)0.69 (0.11) \\ \hline Left & & & & & & & & & & \\ \hline Overall & 150 & 31.90 & 0.85 (0.07) & 29.72 & 0.93 (0.08) & 26.86 & 0.71 (0.06) & 2.18 (0.10) & 2.86 (0.10) & 5.04 (0.10) \\ \hline ROI & 150 & 32.83 & 2.55 (0.21) & 32.83 & 1.15 (0.09) & 32.57 & 0.87 (0.07) & 0.00 (0.20) & 0.26 (0.20) & 0.26 (0.20) \\ \hline Right & & & & & & & & & & \\ \hline Overall & 150 & 31.67 & 0.79 (0.06) & 29.96 & 1.08 (0.09) & 26.67 & 0.70 (0.06) & 1.81 (0.10) & 3.19 (0.10) & 5.00 (0.10) \\ \hline ROI & 150 & 33.06 & 0.80 (0.07) & 32.85 & 0.96 (0.08) & 32.35 & 0.93 (0.04) & 0.21 (0.10) & 0.50 (0.10) & 0.71 (0.10) \\ \hline \hline \end{tabular} \({}^{\circ}\)–C\({}_{\circ}\)–Colius; cm–committee; \(\pi\)–number; SD–standard deviation; SE–standard error; ROI–region of interest.  
\end{table} 
Table 3: The mean overall temperature and the mean temperature at the region of interest (ROI) measured from the thermographic images. \begin{table}
\begin{tabular}{l c c c} \hline \hline \multicolumn{1}{c}{**Profile Views**} & \multicolumn{1}{c}{**Mean Overall Temperature**} & \multicolumn{1}{c}{**Mean ROI**} \\ \hline Front & Total \(n\) & 450.00 & 450.00 \\ \hline  & Test Statistic & 368.018  & 80.176  \\ \hline  & df & 2.00 & 2.00 \\ \hline  & \(p\)-value & \(<\)0.001 & \(<\)0.001 \\ \hline Left & Total \(n\) & 450.00 & 450.00 \\ \hline  & Test Statistic & 384.353  & 21.399  \\ \hline  & df & 2.00 & 2.00 \\ \hline  & \(p\)-value & \(<\)0.001 & \(<\)0.001 \\ \hline Right & Total \(n\) & 450.00 & 450.00 \\ \hline  & Test Statistic & 364.811  & 49.451  \\ \hline  & df & 2.00 & 2.00 \\ \hline  & \(p\)-value & \(<\)0.001 & \(<\)0.001 \\ \hline Right & Total \(n\) & 450.00 & 450.00 \\ \hline  & Test Statistic & 364.811  & 49.451  \\ \hline  & df & 2.00 & 2.00 \\ \hline  & \(p\)-value & \(<\)0.001 & \(<\)0.001 \\ \hline \hline \end{tabular} ROI—region of interest; \(n\)—number; df—degree of freedom; \({}^{\text{a}}\) The test statistic was adjusted for ties; \(p\)-value Kruskal-Wallis; significance: \(p=0.05\).  
\end{table}