## 4 Discussion
Discrepancies in the fracture resistance of AM-fabricated temporary restorations can arise from differences in material composition, polymerization protocols, and post-processing procedures [30]. The post-curing process plays a critical role in determining the mechanical properties of 3D-printed resins, with variations in post-curing time significantly affecting these characteristics [31]. Studies have shown that increasing the post-curing time improves the fracture resistance of 3D-printed restorations, particularly in oblique and horizontal orientations. While shorter curing times favor oblique prints, extending the duration to 30-60 min enhances strength across all orientations. However, a further extension to 90-120 min provides minimal benefit for vertically printed specimens. This may suggest that different layer orientations interact differently with residual monomer conversion, due to variations in the surface area of the laminated layers [16]. Some studies have further suggested that a 90-degree printing orientation contributes to higher fracture strength, potentially explaining the greater resistance reported with the AM technique in certain investigations [12; 27]. A recent systematic review evaluating the impact of printing orientation on the physical and mechanical properties of fixed dental prostheses concluded that orientation does, indeed, affect the fracture resistance of resin crowns and prostheses. However, due to substantial heterogeneity among the included studies, in terms of materials, printing technologies, post-processing, and test methods, no definitive conclusion could be drawn regarding the optimal orientation [16]. In their study, [PERSON] et al. [44] used SLA and DLP-based AM technique to fabricate restorations from P pro Crown & Bridge (methacrylate resin). Compared to the present study, they obtained lower fracture resistance values, which may be attributed to their use of a 100 \(\upmu\)m layer thickness, given that the degree of conversion depends on layer thickness. Moreover, in the present study, Optiglaze was applied to achieve a smoother surface; however, no surface treatment was mentioned in the study by [PERSON] et al. According to DLP principles, as each slice is cured from a single screen displayed by the chipset, fractures may occur more rapidly if the surface is rough [13]. [PERSON] et al. [29] examined temporary fixed partial dentures fabricated using different manufacturing methods. Given that their study did not involve an aging process, the findings for non-aged restorations were consistent with the present study. However, the maximum fracture strength values they reported were higher than those observed in the present study, potentially due to the use of metal dies or variations in the materials tested. The material of the die can affect fracture resistance; therefore, resin dies were employed rather than metal dies to obtain values that were more representative of clinical reality [27]. Precision is critical when using a dental die, as it directly affects the design, fabrication, and assessment of a crown [45]. Unlike extracted teeth, which may vary in morphology and surface characteristics, 3D-printed resin dies provide uniformity and reproducibility, thus reducing the variability that might influence test outcomes [46]. Nonetheless, 3D-printed dies can exhibit significant distortion after one to three months of storage, especially under light exposure. Consequently, all detailed work on resin-based 3D-printed dies was performed within the first three weeks after manufacture, when dimensional changes were minimal [45; 47].