## 4 Discussion
This result suggests that, in certain situations, the properties of Evoflex material may be comparable when paired with a straight design of the aligner margins. The results demonstrate that all analyzed aligners had at least one model with significantly different mean force values, highlighting how specific design features and material characteristics influence their performance. Comparison of maximum force among aligners for each model and among models for each aligner confirms that aligner retention varies significantly based on model configuration, malocclusion type, and design, highlighting the importance of accurate treatment customization. Noxi aligners with high margins with both horizontal and vertical gradients demonstrated superior retention compared to scalloped aligners in cases of dental crowding. These findings align with those of [PERSON] et al. [10], who emphasized the critical role of margin design in retention. Unlike scalloped margins, the high straight margin of Noxi aligners provided better retention, particularly in models with moderate crowding. The analysis of aligner retention in cases of crowding and aligned adult further underscores the advantages of variable thickness in Noxi aligners. This feature enables better control over displacing forces, reducing the need for additional grip points. These results are consistent with the findings of [PERSON] et al. [12], which showed that increased thickness enhances device stability. The data confirm that, regardless of aligner type, models with mixed dentition exhibit significantly lower retention compared to other configurations. This suggests that aligners should not be the first choice for children with mixed dentition unless additional grip points are incorporated to improve retention. Grip points were shown to increase the force required to displace aligners across all models analyzed. However, in Noxi aligners with high margins with vertical and horizontal gradients, retention values were high under crowding conditions, suggesting that the use of grip points may not be necessary in this scenario. In recent years, the demand for aesthetic solutions during orthodontic treatment has grown significantly [2; 32]. The introduction of Noxi aligners (Sweden&Martina, [PERSON], Italy), developed by the University of Ferrara, offers a 3D-printed aligner option that can be worn for only 12 h per day, addressing the needs of patients seeking a more discreet and less demanding treatment alternative. Studies highlight that only a small percentage of patients fully adhere to traditional 22-h wear protocols [33]. This innovation aims to enhance patient compliance--one of the key factors for orthodontic treatment success--by significantly reducing the required wear time. Polyamide, the material used for these aligners, demonstrated reduced stress relaxation compared to traditional materials, enabling the application of higher forces over extended periods, thereby facilitating effective orthodontic movement [27]. Additionally, unlike thermoforming, 3D printing allows for differentiated thicknesses, enabling the force to be precisely calibrated for specific areas of the dental arch, thereby improving treatment efficiency and customization. In conclusion, Noxi polyamide aligners with high margins with both horizontal and vertical gradients represent a viable alternative to thermoformed aligners, offering excellent retention control, particularly in cases involving crowding or high retention needs. The strength of the present research lies in its comprehensive evaluation and comparison of the retention force of various configurations of thermoformed and 3D-printed aligners tested across models representing six distinct types of malocclusions, thus simulating a wide range of occlusal conditions. Since the study was conducted in vitro, it was possible to apply forces higher than those typically exerted clinically to test the conditions under more extreme circumstances.