## 4 Discussion  
This study investigated the first point of view of the four groups of subjects in order to identify a possible difference in the approach and definition of aesthetics between laypersons and experts in this field. The methodology used was the eye-tracker described in the literature, which is non-invasive and harmless to the health of the subjects due to corneal reflection using infrared light [22, 23]. In the study by [PERSON] et al. [24], 47 laypersons were shown intraoral images of teeth with and without restorations and the gaze points and duration of each were evaluated with an eye-tracker. The restorations were subsequently inserted into photographs of the mouth-closed and mouth-opened condition using an editing program. This was done only on one side in each of the four quadrants and did not fit aesthetically into the overall image. Consequently, a sequence of images was created, showing unprocessed photos and photos with non-aesthetic restorations. The first fixation point in the images shown with restorations was significantly more often detectable first on the restoration and the viewing of the restoration was additionally of longer duration. No difference in viewing time was observed in the photos without non-esthetic restorations [24]. In contrast in the present study design, also the identification \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**Correlations**} & & \\ \hline \multicolumn{1}{c}{} & & **Rating** & **Gender** & **Status** & **Age** & **First\_Eyefixation** \\ \hline \multirow{8}{*}{Kendall-Tau-b} & \multirow{2}{*}{Rating} & Correlation coefficient & 1000 & \(-\)0.006 & 0.013 & * \(-\)0.069 & * \(-\)0.069 \\  & & Sig. (two-sided) & - & 0.815 & 0.57 & 0.003 & 0.003 \\  & & N & 1200 & 1200 & 1200 & 1200 & 1200 \\ \cline{2-8}  & \multirow{2}{*}{Gender} & Correlation coefficient & \(-\)0.006 & 1000 & * 0.226 & * 0.212 & 0.023 \\  & & Sig. (two-sided) & 0.815 & - & \(<\)0.001 & \(<\)0.001 & 0.391 \\  & & N & 1200 & 1200 & 1200 & 1200 & 1200 \\ \cline{2-8}  & \multirow{2}{*}{Status} & Correlation coefficient & 0.013 & * 0.226 & 1000 & * \(-\)0.27 & 0.033 \\  & & Sig. (two-sided) & 0.57 & \(<\)0.001 & - & \(<\)0.001 & 0.173 \\  & & N & 1200 & 1200 & 1200 & 1200 & 1200 \\ \hline \multirow{8}{*}{Age} & Correlation coefficient & * \(-\)0.069 & * 0.212 & * \(-\)0.27 & 1000 & \(-\)0.028 \\  & & Sig. (two-sided) & 0.003 & \(<\)0.001 & \(<\)0.001 & - & 0.266 \\ \cline{1-1}  & & N & 1200 & 1200 & 1200 & 1200 & 1200 \\ \hline \multirow{8}{*}{First\_Eyefixation} & Correlation coefficient & * \(-\)0.069 & 0.023 & 0.033 & \(-\)0.028 & 1000 \\ \cline{1-1}  & Sig. (two-sided) & 0.003 & 0.391 & 0.173 & 0.266 & - \\ \cline{1-1}  & & N & 1200 & 1200 & 1200 & 1200 & 1200 \\ \hline \hline \end{tabular}  
* The correlation on level 0.01 is significant (two-sided).  
\end{table} 
Table 1: Kendall tau correlation. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Non-Standardized Coefficients**} & \multicolumn{2}{c}{**Standardized**} & & & & \\ \cline{2-8}  & & **Reg. Coefficient B** & **Std.-Mistake** & **Beta** & **T** & **Sig.** & **Lower Limit** & **Upper Limit** \\ \hline Constant & 1.875 & 0.172 & - & 10.874 & \(<\)0.001 & 1.537 & 2.213 \\ Gender & 0.117 & 0.085 & 0.043 & 1.379 & 0.168 & \(-\)0.05 & 0.284 \\ Status & \(-\)0.013 & 0.041 & \(-\)0.011 & \(-\)0.302 & 0.763 & \(-\)0.094 & 0.069 \\ Age & \(-\)0.067 & 0.031 & \(-\)0.075 & \(-\)2.176 & 0.03 & \(-\)0.128 & \(-\)0.007 \\ \hline \hline \end{tabular}  
* Dependent variable: First\_Eyefixation.  
\end{table} 
Table 2: Regression. of the difference between laypersons and experts, who could have different approaches to the observation due to their level of experience, should be performed. The hypothesis that experts pay more attention to the \"problem area\" and laypersons primarily look at the central incisor cannot be confirmed.