## 3 Results
### Summary of the Main Trends  
The present study found a significant influence of the type of reinforcement and the type of polymer material on the physico-mechanical characteristics of laboratory and clinical test specimens of dental composites, including flexural strength (FS/MPa), maximum force before fracture (Fmax/N), and modulus of elasticity (E/MPa). On the other hand, the method of storage did not show a significant influence on the physico-mechanical characteristics. Table 4 provides a summary of the main trends observed for different types of reinforcements in terms of flexural strength (FS/MPa), maximum force before fracture (Fmax/N), and modulus of elasticity (E/MPa). Notably, when controlling for the type of polymer material, optimal values for flexural strength and maximum force before fracture were consistently associated with specific types of reinforcement. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Main Trends** & \multicolumn{2}{c}{**Reinforcement**} \\ \hline \hline \multicolumn{2}{c}{Flexural strength (FS/MPa) and maximum strength before fracture (Fmax/N)} \\ \hline \hline \multirow{2}{*}{Highest values} & \(\succeq\) & Fiberglass thread coated with light-cured composite \\  & & (Interlig, Angelus, 8.5 \(\times\) 0.2 mm) \\  & \(\succeq\) & Fiberglass strand (Fiber Splint Polydentia One Layer) \\ Second largest values & \(\succeq\) & Polyethylene thread (Ribbond Regular, 4.0 mm) \\ \hline \hline \multicolumn{2}{c}{Elasticity (E/MPa)} & Reinforcement \\ \hline \hline \multirow{2}{*}{Highest values} & \(\succeq\) & Fiberglass thread (Fiber Splint Polydentia One Layer) \\  & \(\succeq\) & Polyethylene thread (Ribbond Regular, 4.0 mm) \\ Second largest values & \(\succeq\) & Fiberglass thread coated with light-cured composite \\  & & (Interlig, Angelus, 8.5 \(\times\) 0.2 mm) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Main trends regarding the physico-mechanical characteristics of the test specimens according to the type of reinforcement. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Physico-Mechanical** & \multicolumn{2}{c}{**Storage at Room Temperature**} & \multicolumn{2}{c}{**Storage in Distilled Water at**} \\
**Characteristics** & \multicolumn{2}{c}{**Estimated Marginal Mean (SD)**} & \multicolumn{2}{c}{**Room Temperature**} \\  & & **Estimated Marginal Mean (SD)** & \\ \hline Flexural strength (FS/MPa) & 75.06 (17.96) & 73.87 (19.23) & 0.226 \\ Maximum force before fracture & 20.017 (4.80) & 19.70 (5.13) & 0.229 \\ (Fmax/N) & 7855 (1530) & 7689 (1522) & 0.064 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Influence of the method of storage on the physico-mechanical characteristics of laboratory and clinical test specimens of dental composites. Table 5 summarizes the main trends for the types of polymer materials regarding flexural strength (FS/MPa), ultimate strength before fracture (Fmax/N), and elasticity ((E/MPa). Similar to the type of reinforcement, flexural strength (FS/MPa) and maximum strength before fracture (Fmax/N) showed optimal values for the same type of polymers when the effect of the type of reinforcement was statistically controlled. The comparison of the strength properties (compressive strength, ultimate strength before fracturing, and elastic modulus) of the test specimens of three types of laboratory dental polymers for PNPCs (heat-cured, factory-cured for subtractive manufacturing by CAD/CAM, light-cured for additive manufacturing by CAD/CAM) and three types of clinical dental polymers for PNPCs (self-polymerizing, light-polymerizing, light- and self-polymerizing (double-polymerizing)) showed the following three polymer materials as yielding the best characteristics:  
Factory-polymerized PMMA material for subtractive CAD/CAM fabrication (DD temp MED, Dental Direkt GmbH, Germany): this material exhibited the best mechanical properties with a flexural strength (FS) of 83.56 \(\pm\) 15.35 MPa, maximum force before fracturing (Fmax) of 22.29 \(\pm\) 4.09 N, and an elastic modulus (E) of 7631.24 \(\pm\) 352 MPa.