## 2 Materials and Methods
### Accuracy Evaluation via Surface Comparison  
The printed occlusal devices (\(n=10\) (2.5 mm); \(n=10\) (4.5 mm)) were digitized by an industrial structured light scanner (ATOS III Triple Scan, GOM, Topometric GmbH, Goppingen, Germany) to obtain virtual test objects as stl files for accuracy analysis. According to the measuring equipment monitoring protocol the structured light scanner had \begin{table}
\begin{tabular}{c c} \hline \hline  & **Resin** \\ \hline Flexural Strength [MPa] & \textgreater{}80 \\ \hline Elastic Modulus [MPa] & \textgreater{}2000 \\ \hline Water Absorption [ug/mm\({}^{3}\)] & \textless{}32 \\ \hline Solubility [ug/mm\({}^{3}\)] & \textless{}5 \\ \hline Hardness [Shore D] & \textgreater{}82 \\ \hline Color & clear-transparent \\ \hline Curing Wavelength [nm] & 385 \\ \hline \hline \multicolumn{2}{c}{**CAM Settings**} \\ \hline Printer & \\ \hline DMD projector resolution [pixels] & 1920 \(\times\) 1024 \\ \hline Spectral Maximum of LED & 385 nm \\ \hline Membrane Type of Material Unit & flexible \\ \hline Support Structures & \\ \hline Distribution & based on object geometry \\ \hline Density & Medium \\ \hline Size & Medium \\ \hline Spherical Support Tip & Yes \\ \hline \multicolumn{2}{c}{Oclusal Device} \\ \hline Orientation Strategy & Optimized quality \\ \hline Detail Level (Layer Thickness [\(\upmu\)m]) & Very high (50) \\ \hline \multicolumn{2}{c}{Post-Processing} \\ \hline Washing Solution & 99.9\% isopropyl alcohol \\ \hline \hline \end{tabular}
\end{table} 
Table 1: 3D Printing Parameters. a maximum trueness deviation of 4 \(\upmu\)m. The precision was \(\leq\)15 \(\upmu\)m. For scanning, the test objects were equipped with reference markers. Internal (Figure 1c) and external surfaces (Figure 1d) of the devices were scanned in two separate measurement series consisting of 20-30 single shots each with varying camera angles. Markers were necessary to match all scans to one three-dimensional data set. The according data sets were referred to as [2.5_TOTAL] and [4.5_TOTAL]. To obtain the reference data in stl format, system specific cam files of the virtually planned 2.5 and 4.5 devices had to be converted. The data of the reference and the test objects were imported in a 3D analysis software (GOM Inspect Suite 2020, GOM GmbH, Braunschweig, Germany) for analysis. The computer-aided design (CAD) stl files were aligned with the corresponding scan stl files of the printed occlusal device ([2.5_TOTAL] and [4.5_TOTAL]) for trueness evaluation. To register two different stl files in one coordinate system both files were superimposed via best-fit alignment. After that, surface comparison was performed (Figure 1e,f). For analysis, two approaches were taken. Next to the total surface [2.5_TOTAL; 4.5_TOTAL] of the occlusal device, the internal surfaces [2.5_INTERNAL; 4.5_INTERNAL] (Figure 1g,h) were evaluated to focus on the fit of the devices on the occlusal surfaces of the teeth. Therefore, the external surface of the devices was cut-off. Before point-to-surface measurement, the maximum tolerance was set to one millimeter and the surface comparison was applied on the test object. The values of the point-to-surface measurements between two surfaces were exported as absolute values in American Standard Code for Information Interchange (ASCII). A self-programmed python script was used for automated data evaluation. For each file the absolute mean deviation, root mean square error, median, standard deviation, and minimal and maximal distances were calculated. RMSE is defined as:  
\[RMSE=\sqrt{\frac{1}{n}\sum_{i=1}^{n}(x_{i}-\mu_{i})^{2}}\]  
where \(x_{i}\) are the predicted values of the reference cast, \(\mu_{i}\) are the observed values of the test cast, and n is the number of observations. The RMSE describes the dispersion around a true value with respect to trueness and precision. To check precision, each group's scans (\(n\) = 10: [2.5_TOTAL]; [4.5_TOTAL]; and [4.5_INTERNAL]) were compared among each other resulting in 45 surface comparisons per group. The data analysis was performed as above.