## 4 Discussion  
Based on the results of this study, the null hypothesis, \"the method of selecting landmarks manually or using AI in smile design programs does not affect the esthetic perception of the resulting smile design,\" was rejected. The study found significant differences in the esthetic perception of smile designs created manually or by AI. As digital technology improves and people become more concerned with esthetics, DSD programs have become increasingly popular in dentistry [3; 4; 7; 8]. Accurate diagnosis and treatment planning are crucial in esthetic dentistry, and DSD programs allow for virtual esthetic analysis and treatment planning using edited photographs or digital patient models [11]. Using 3D digital design can increase patient satisfaction and treatment success [4]. DSD programs provide; however, the ideal features that DSD programs should have are still being researched. A review of commonly used DSD programs found that if one or more esthetic parameters are neglected, the ideal treatment plan and results cannot be achieved. Therefore, it is believed that the selection of landmarks affects treatment planning and the esthetics of the restoration created by the program [5]. In this study, the landmarks were selected manually by the clinician and automatically by AI. The automatic selection of landmarks by AI saves time, but the fact that dentists generally found the cases with manually selected landmarks to be more esthetically pleasing raises questions about the effectiveness of AI. For the most accurate determination of symmetry and asymmetry in facial analysis, as many reference points as possible should be used [24]. In the AI mode of the smile design program used in this study, 68 facial points were determined using Microsoft face API. It was observed in Case 3 that orthodontists preferred the AI-generated smile design at a statistically significant rate compared to other specialties. This may be due to the fact that orthodontists use FM more frequently during treatment, leading to their heightened perception of smiles [12]. The reason orthodontists had different esthetic perceptions in our study may be attributed to this. In a study comparing landmarks marked by orthodontists to those drawn by AI, a high degree of similarity was found [17]. This suggests that orthodontists may have preferred the AI designs in our study due to their familiarity with AI values or experience with treatments based on these familiar landmarks [18]. In contrast, when examining Case 4 (which featured a symmetrical facial feature), there was no significant difference in preference for manually created or AI-generated designs among dentists and other occupations (\(p=0.001\)). It can be concluded that in complex cases, dentists' esthetic perception is different from that of people in the non-professional group [13]. The results of the survey suggest that there is a significant difference in the esthetic perception between dentists and laypeople, similar to findings from another study [1]. This indicates that there may be a discrepancy between the esthetic perceptions of patients and dentists during treatment. For years, clinicians, researchers, and programmers have favored mathematical approaches for creating symmetrical smiles. However, the FF concept allows for more organic and natural smile designs on both symmetrical and asymmetrical faces. While traditional smile design methods often aim for symmetry by using straight lines, such as the dental midline, as a reference, the FF concept takes into account human perception and may be more suitable for asymmetrical faces [19]. In DSD applications, mathematical algorithms are used to create a new design based on determined landmarks. While AI and DSD programs may produce good results in patients with good facial symmetry, manual methods may be preferred in cases where facial symmetry is impaired.