## 4 Discussion  
This study aimed to evaluate the in vivo and in vitro accuracy of s-CAIS in an end-tulous patient using two different evaluation techniques and to investigate if both can be applied to edentulous patients. When evaluating the accuracy of s-CAIS, the most assessed parameters are angular deviation, and deviation at the entry point and the apex of the implant. In the clinical part of the experiment, a maximum angular deviation of 5.3\({}^{\circ}\) was noticed at implant site 32, while in the in vitro CBCT evaluation, the maximum angle of deviation was 4\({}^{\circ}\) at implant site 42, and 5.1\({}^{\circ}\) at the same site with the STL assessment. Deviations between the planned and achieved implant positions should be expected because of inaccuracies in the various procedures during template design and manufacturing [32; 33]. At the same time, the use of such an individualized template allows appropriate bone reduction for obtaining a predictable surgery and prosthetic stage [34]. The limitations of the study were related to the fact that during implant placement, several clinical factors can affect the accuracy of final treatment and some of them (different bone density guiding the osteotomy, different possible fit of a bone-supported template, stability, and fixation of the template) are missing in the in vitro part of the experiment. In this clinical report, the treatment evaluation was affected by the DICOM-to-DICOM matching procedure, as well as possible errors during CBCT acquisition. On the contrary, in the in vitro part of the study, dental implants seemed to be placed more accurately with the initial planning. Figure 4: (**A**) Scan bodies mounted on the implants placed in vitro; (**B**) Planning CBCT and postoperative STL matching; (**C**) Accuracy analysis between STL file and scan bodies. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Tooth Position** & **Angle** & \begin{tabular}{c} **3D Offset** \\ **(Base)** \\ \end{tabular} & \begin{tabular}{c} **Distal** \\ **(Base)** \\ \end{tabular} & \begin{tabular}{c} **Vestibular** \\ **(Base)** \\ \end{tabular} & \begin{tabular}{c} **Apical** \\ **(Base)** \\ \end{tabular} & \begin{tabular}{c} **3D Offset** \\ **(Tip)** \\ \end{tabular} & \begin{tabular}{c} **Distal** \\ **(Tip)** \\ \end{tabular} & \
\begin{tabular}{c} **Vestibular** \\ **(Tip)** \\ \end{tabular} &
\begin{tabular}{c} **Apical** \\ **(Tip)** \\ \end{tabular} \\ \hline
**35** & 3.1 & 0.13 & \(-\)0.07 & 0.08 & 0.06 & 0.47 & \(-\)0.02 & \(-\)0.46 & 0.08 \\
**32** & 3.2 & 0.71 & 0.17 & 0.38 & 0.57 & 0.83 & 0.55 & \(-\)0.18 & 0.59 \\
**42** & 5.1 & 0.62 & \(-\)0.35 & 0.06 & 0.51 & 1.1 & 0 & \(-\)0.95 & 0.55 \\
**45** & 4.1 & 0.4 & \(-\)0.18 & 0.08 & 0.35 & 0.64 & 0.43 & \(-\)0.28 & 0.38 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Accuracy analysis with STL file of the printed and scanned mandible with implants and scan body inserted. However, several inaccuracies might also occur in the in vitro analysis due to several factors relating to data acquisition and the subsequent 3D printing of the model. According to [PERSON] et al. [33], different types of errors might arise during image acquisition and data processing. There is a correlation between the dataset volume extracted from the CBCT and the CBCT resolution, as reported by [PERSON] [35]. Evaluating the results, the explanation for this is that when the CBCTs were created with a resolution of 0.2 voxels, a matching precision greater than 0.2 mm is not achievable. This error might have been doubled when printing the exported DICOM dataset of the mandible. Hence, volume shrinkage could be noticed at the matching stage. According to [PERSON] et al. [36], there is also some inaccuracy due to 3D printing procedures. The 3D printer used in the present study had a precision of 35 \(\upmu\)m, according to the manufacturer.