## 4 Discussion
These findings are consistent with the previous research, which shows that increased polymerization times enhance the degree of cross-linking, thereby improving the mechanical properties of dental resins [45; 46]. For Tera Harz TC 85, the storage modulus analysis indicates that the 4 s polymerization time serves as a reliable control. No significant differences in E\({}^{\prime}\) are observed between the 3 s and 4 s times or between the 2.4 s and 4 s times, indicating similar stiffness for these durations. However, significant differences are found between the 4 s control and both the 2 s and 4.5 s polymerization times, with these shorter and longer exposure times resulting in higher E\({}^{\prime}\) values. The higher E\({}^{\prime}\) at 2 s could be due to a rapid initial reaction, leading to an unexpectedly efficient cross-linking. The increased E\({}^{\prime}\) at 4.5 s indicates that extended polymerization enhances the cross-link density, resulting in a stiffer material. These results align with the literature, suggesting that both insufficient and extended polymerization can lead to increased material stiffness due to variations in the degree of cross-linking and polymer network formation [47; 48; 49; 50]. Both NextDent Orto Flex and Tera Harz TC 85 show that the polymerization time critically affects the storage modulus. For NextDent, a polymerization time of around 7 s appears optimal, while for Tera Harz, both very short and extended times (2 s and 4.5 s) enhance stiffness. The glass transition temperature (Tg) is a critical metric for evaluating the thermal properties of polymer-based dental resins, as it indicates the temperature at which a material shifts from a glassy, rigid state to a rubbery, flexible state. Understanding Tg helps in determining the material's performance and stability under different conditions [27; 28]. In the context of NextDent and Tera Harz resins, the polymerization time significantly influences Tg, reflecting the extent of polymer cross-linking and the resulting thermal stability of the material. NextDent demonstrates a higher Tg compared to Tera Harz, indicating a more tightly bound polymer network and thus greater thermal stability. Aromatic groups can increase Tg due to restricted chain mobility and increased intermolecular forces [51], implying that the lower presence of aromatic groups in Tera Harz TC 85 compared to NextDent Orto suggests that Tera Harz TC 85 might have a lower Tg, leading to earlier softening upon heating. The study indicates that reducing the polymerization time to 5 or 6 s decreases Tg significantly, pointing to a less stable thermal structure. Conversely, extending the polymerization time to 8 s does not notably affect Tg, indicating an optimal polymerization time of around 7 s for achieving the best thermal properties for NextDent. Higher flexibility indicated by prominent skeletal C-C stretching might lead to a lower Tg, as the polymer chains can move more freely at lower temperatures [52]. For Tera Harz, the findings indicate a different optimal polymerization strategy. The 4 s polymerization time serves as the control, with no significant differences in Tg observed for polymerization times of 2, 2.4, or 3 s, indicating similar thermal stability across these durations. However, a significant increase in Tg is noted at 4.5 s, indicating that longer polymerization enhances the thermal stability of Tera Harz. These results align with the broader literature, which consistently shows that the degree of polymerization and cross-link density are key determinants of Tg [53]. Higher cross-link densities typically correlate with higher Tg due to reduced molecular mobility within the polymer network [54]. For NextDent, a 7 s polymerization time appears optimal for achieving high thermal stability, while for Tera Harz, a polymerization time of 4.5 s is recommended to enhance Tg and thermal stability. The correlation analysis among E\({}^{\prime}\), Tg, and DC reveals important insights into the material properties of polymer-based dental resins.