## 4 Discussion
The significant positive correlation between E\({}^{\prime}\) and Tg indicates a direct relationship between the mechanical strength and thermal stability of the material. This implies that as the stiffness of the resin increases, so does its resistance to thermal deformation, likely due to a denser cross-linked polymer network [54]. Conversely, the moderate negative correlation between Tg and DC indicates a trade-off between thermal stability and the extent of polymerization. This relationship suggests that achieving higher Tg might involve conditions that lead to a lower degree of monomer conversion. This inverse relationship highlights the challenge of optimizing both properties simultaneously and suggests that adjustments in polymerization protocols might be needed to balance these attributes effectively. The lack of a significant correlation between E\({}^{\prime}\) and DC indicates that while both properties are influenced by the polymerization process, they are not directly dependent on each other. This suggests that other factors, such as the nature of the monomers and the specifics of the polymerization process, play a more significant role in determining the storage modulus independently of the degree of conversion. Our findings on the polymerization times and material properties of NextDent Orto Flex and Tera Harz TC 85 have important clinical implications for dental aligners. Tera Harz TC 85's higher degree of conversion (DC) indicates fewer residual monomers, potentially making it healthier for patients. However, its lower glass transition temperature means it could become rubbery in the mouth due to temperature variations. On average, an oral temperature of approximately 34 \({}^{\circ}\)C can be measured over a 24 h period [55]. Temperature naturally fluctuates due to factors such as food and beverage intake, ambient temperature changes, mouth breathing, and smoking. For instance, [PERSON] et al. observed temperatures ranging from 1.62 \({}^{\circ}\)C to 65.43 \({}^{\circ}\)C during the consumption of hot or cold beverages [56]. NextDent Orto Flex, with its higher storage modulus and Tg, offers greater rigidity and stability at higher temperatures, ideal for applying significant orthodontic forces. However, its lower DC raises concerns about residual monomers and potential health implications. Future studies are needed to further evaluate the long-term health effects and performance of these materials under varying clinical conditions. This study has several limitations, including limited sample size and diversity, which may affect the generalizability of the results. The experiments were conducted under controlled laboratory conditions that do not fully replicate the dynamic environment of the oral cavity, where factors such as saliva, varying pH levels, and mechanical wear could influence material properties. Additionally, the study focused on specific UV exposure durations and immediate material properties post-polymerization, necessitating further research to explore a broader range of exposure times, long-term performance, and potential health implications of residual monomers. Finally, patient comfort and clinical efficacy were not assessed, which are crucial for the practical application of dental aligners.