# Study of Root Canal Length Estimations by 3D Spatial Reproduction with Stereoscopic Vision
## 3 Results
### Subjective Evaluation  
The Likert scale feedback questionnaire administered after the first measurement with SRD and 2D devices showed high ratings for the evaluations related to stereoscopic vision (mean rating 9.4/10), image delay (mean rating 9.3/10), and their use in clinical and educational settings (mean rating 9.3/10). These ratings were consistently above 9 on average. Ratings with some variabilities were observed for motion sickness (mean rating 7.9/10) and eye fatigue (mean rating 7.4/10), with the lowest rating of 3 points for eye fatigue (Table 3).  
Open-ended responses were received from 24 of the 40 participants. After categorizing the responses using topic modeling, the identified problems with SRD use included six cases related to operability, four cases related to eye fatigue, two cases related to motion sickness, and four other cases. The reported benefits included 10 cases related to depth perception, 5 cases related to clinical education for clinical application, 4 cases related to operability, and 3 cases related to educational application. Suggestions for improvement included five cases to improve operability, four cases to improve image quality, and four cases to explore applications in other fields.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Device**} & \multirow{2}{*}{**Model**} & \multirow{2}{*}{
\begin{tabular}{c} **Number of** \\ **Measurement** \\ \end{tabular} } & \multicolumn{3}{c}{**Measurements of Root Canal (mm)**} & \multicolumn{3}{c}{**Measurement Time (s)**} \\ \cline{3-8}  & & & **Mean (SD)** & **Min** & **Max** & **Mean (SD)** & **Min** & **Max** \\ \hline \multirow{8}{*}{SRD} & \multirow{2}{*}{\#24} & 1 & 22.97 (0.04) & 22.85 & 23.06 & 20.31 (8.01) & 6.72 & 43.06 \\ \cline{3-8}  & & 2 & 22.95(0.04) & 22.88 & 23.04 & 14.82 (3.79) & 6.48 & 23.76 \\ \cline{3-8}  & & 1 & 21.24 (0.13) & 20.84 & 21.44 & 20.86 (6.90) & 8.65 & 39.19 \\ \cline{2-8}  & & 2 & 21.25 (0.15) & 20.86 & 21.48 & 17.40 (5.52) & 8.17 & 31.94 \\ \cline{2-8}  & & 1 & 20.81 (0.10) & 20.58 & 20.96 & 22.06 (8.10) & 8.17 & 40.98 \\ \cline{2-8}  & & 2 & 20.81 (0.10) & 20.51 & 20.96 & 15.79 (5.09) & 6.14 & 26.73 \\ \cline{2-8}  & & 1 & 22.86 (0.13) & 22.57 & 23.08 & 19.32 (5.85) & 8.96 & 28.73 \\ \cline{2-8}  & & 2 & 22.85 (0.14) & 22.50 & 23.02 & 14.38 (4.00) & 6.89 & 22.64 \\ \hline \multirow{8}{*}{2D device} & \multirow{2}{*}{\#24} & 1 & 22.90 (0.21) & 22.39 & 23.30 & 48.15 (15.68) & 23.39 & 79.69 \\ \cline{2-8}  & & 2 & 22.91 (0.19) & 22.51 & 23.32 & 44.48 (13.71) & 22.55 & 74.23 \\ \cline{2-8}  & & 1 & 21.18 (0.41) & 20.23 & 21.94 & 54.69 (20.12) & 21.73 & 105.84 \\ \cline{2-8}  & & 2 & 21.15 (0.40) & 20.16 & 21.92 & 51.73 (19.03) & 22.21 & 101.06 \\ \cline{2-8}  & & 1 & 20.84 (0.36) & 20.24 & 21.51 & 56.43 (20.06) & 25.45 & 107.86 \\ \cline{2-8}  & & 2 & 20.86 (0.30) & 20.25 & 21.48 & 51.46 (18.71) & 23.34 & 95.50 \\ \hline \multirow{8}{*}{\#44} & 1 & 22.85 (0.32) & 22.28 & 23.71 & 51.84 (15.68) & 23.98 & 83.57 \\ \cline{2-8}  & & 2 & 22.82 (0.35) & 22.05 & 23.60 & 48.66 (16.63) & 25.12 & 90.27 \\ \hline \hline \end{tabular} SD, standard deviation; SRD, spatial reality display; and 2D, two-dimensional.  
\end{table}
Table 2: Measurements of the root canal length for each device and tooth model.