## 4 Discussion  
This study has several limitations that should be acknowledged. Firstly, the sample size used in the study was relatively small, which may restrict the generalizability of the findings to a larger population. Future studies should consider increasing the sample size to enhance the robustness of the results. Another limitation is that the printed material was exposed to a single testing session, which may not accurately reflect its long-term behavior under repeated cyclic loads. It is essential to investigate the material's durability and stability over time to assess its suitability for orthodontic applications. The geometry of the diaphragm samples was simplified, as they were printed in a rectangular shape rather than replicating the complex dental arch shape. This simplified geometry may not fully capture the intricate mechanical behavior and stress distribution observed in real-life orthodontic scenarios. Future studies could explore more realistic sample geometries to better reflect clinical conditions. Furthermore, the study focused on a limited set of evaluation indexes for mechanical properties, potentially overlooking other important parameters. A more comprehensive assessment, encompassing a wider range of evaluation indexes, would provide a complete understanding of the material's mechanical behavior. It is important to note that this study was conducted in an in vitro laboratory setting, which may not fully replicate the dynamic and complex oral environment. To validate the findings and ensure their relevance in clinical practice, further research involving in vivo or clinical studies is necessary. Additionally, the study primarily compared the printed material to nickel-titanium wires, neglecting a comparison with other commonly used orthodontic  
Figure 4: Maximum load (continuous line) and polynomial linear regression (dotted line). materials. Such comparisons are necessary for the ability to assess the material's relative performance and advantages compared to alternative options. The mechanical properties of thermoplastic materials play a key role in achieving the planned orthodontic movements. Aligners should be biocompatible, transparent, and they should have good elasticity, resilience, and low hardness. In this context, it is important to experimentally evaluate the mechanical properties of each material before using it because the data provided by the companies cannot always be considered a reference [5]. In our study, the results of the mechanical tests on the resin-based materials and nickel-titanium wires showed that the resin-based materials had mechanical properties comparable to those of traditional orthodontic materials [6; 13; 20]. Nowadays, thermoforming techniques are the most widespread and used method to produce clear aligners, but 3D-printed aligners are increasingly spreading in the global orthodontic world. The aim of this paper was to compare the mechanical properties of traditional orthodontic materials with new 3D-printing resins [12; 21; 22; 23; 24]. All the samples exhibited the classic load-deflection pattern of shape-memory materials, demonstrating their ability to revert to their original shape after being subjected to stress and suggesting their possible use in orthodontic treatments. The load-deflection pattern provides valuable information on the mechanical behavior of the materials under stress. It will be useful in future studies on the use of resin-based materials in orthodontic treatments. As previously stated by [PERSON] et al., the response to flexural forces is fundamental in orthodontic applications because a model will flex when the aligner is removed [25; 26]. Furthermore, selecting the maximum load value was an important step in analyzing the results, as it allowed for an evaluation of the mechanical properties of the materials under maximum stress. The maximum load values and the other results provided valuable insights into the potential use of resin-based materials as an alternative to traditional orthodontic materials.