## 2 Materials and Methods
### Data Collection  
A standard laboratory protocol was established and applied at the Institute for Research and Advanced Training in Health Sciences and Technologies (IINFACTS-CESPU) in order to test all selected samples.  
Model fabrication was conducted as follows:  
1. Preparation for the experimental phase began with the preparation of 45 samples: 15 temporary PMMA crowns, 15 temporary composite resin crowns, and 15 temporary PEEK crowns, as shown in Figure 1. All temporary crowns were numbered and cataloged for later identification.
2. Temporary crowns were analyzed using a stereoscope (Olympus(r) SZ61--Tokyo, Japan) and a 90\(\times\) magnifying glass in order to ensure the absence of cracks or defects.
3. Each antirotational titanium provisional abutment was screwed onto a laboratory analogue (Figure 2a). The 45 temporary crowns were cemented onto the antirotational titanium temporary abutments with the cement RelyX(r) Unicem 2 Automix (3M(r), Minnesota, USA), with a waiting time of 6 min allowed in order to ensure complete fixation. The cement was atomicx, respecting the manufacturer's instructions. The crowns were filled and cemented to the temporary abutment and stored. These components were then adapted to the load cell fixation table (Figure 2b).
4. The resistance of the crowns was tested using a CS(r) Dental Testing Machine (Barcelona, Spain), as shown in Figure 3a. The CS(r) Dental Testing Machine is a fatigue testing device built in accordance with 2006/42/EC machine safety and EN 12100-1/2, EN 954-1, EN 1037, EN 61310-1/2, EN 60204-1, EN ISO 14121-1, and EN ISO 13850 standards.
5. A piston was activated to transmit a compressive force (at a speed of 1 mm per minute) until fracturing occurred in all PMMA, composite resin, and PEEK crowns, as shown in Figure 3b. The piston was placed in the middle of the occlusal plane between the buccal and palatal cusps. A rubber sheet was placed to serve as a buffer between each of the sample cores and the piston, in order to remove any buildup of stress during the application of force.
6. An Excel CS(r) Dental Testing Machine file was stored on a computer for further graphic and value analysis.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Group** & **Material** & **Brand** & **Quantity** \\ \hline A & PMMA & Temp Basic® & 15 \\  & & (Item number: TMAA1716) & \\ \hline B & Composite Resin & \
\begin{tabular}{c} Lava Ultimate® \\ (Item number: 70-2010-8522-5) \\ \end{tabular} & 15 \\ \hline C & PEEK &
\begin{tabular}{c} Tecno Med Mineral® \\ (Item number: TMAK0112) \\ \end{tabular} & 15 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Sample characterization.  
The types of fracture were also evaluated according to [PERSON]'s classification across the entire sample, as described in Table 2.  
Figure 1: Temporary crowns in CAD/CAM: (**a**) PMMA (Temp Basic®), (**b**) composite resin (Lava Ultimate®), and (**c**) PEEK (Tecno Med Mineral®).  
Figure 3: (**a**) CS® Dental Testing Machine; (**b**) simulated compressive force movement.  
Figure 2: (**a**) Antirotational titanium temporary abutment, laboratory analogue, and screw; (**b**) CAD/CAM crown adapted to the load cell clamping table.