# Preliminary Insights into 3D Cheiloscopy for Forensic Applications: A Pilot Study
## 1 Introduction  
Cheiloscopy, derived from the Greek words keilos (lips) and skopein (to observe), is a forensic identification technique based on the uniqueness of the patterns present in the labial vermillion, much like fingerprints [1]. The distinctive folds and grooves in this region form a unique \"lip print\" that can be used for individual identification [2]. First introduced in the 20 th century, cheiloscopy has since been employed in various forensicapplications, including crime scene investigations and post-mortem identification [3]. However, its practical application has been historically constrained by the limitations of lip print collection and analysis methods [4]. Traditional cheiloscopy relies on lipstick and adhesive tape to transfer lip impressions onto a physical medium. These analog techniques, being simple and accessible, have been widely used due to their ease of application [1]. Typically, a layer of lipstick is applied to the subject's lips, and the impressions of the upper and lower lips are captured on strips of transparent adhesive tape, then transferred to blank cards for analysis. The prints are subsequently examined for unique features and compared with latent lip prints recovered from crime scenes using powders or other lifting techniques. However, despite their widespread use, the reliability of these methods has been questioned, because this process is inherently complex and subjective, as there is no standardized database for systematic matching [2; 5]. Additionally, factors such as pressure variation, lipstick type, and adhesive tape handling can affect the quality of the impressions, making consistent results difficult to achieve [4; 6]. Although these analog approaches remain prevalent due to their practicality and low cost, their limitations underscore the need for more precise and reproducible methods. Previous research has highlighted the importance of developing a standardized database for comparison, which would significantly enhance the utility of cheiloscopy in forensic investigations [7; 8]. Another challenge lies in the numerous classification systems used to categorize lip prints [9]. While these systems aim to organize and interpret lip print patterns, they are often overly didactic and fail to capture the full complexity of lip morphology, limiting their forensic applicability. Moreover, inconsistencies in lip print classification, particularly regarding sex determination, further hinder the reliability of cheiloscopy [10]. While some studies suggest sex-based differences in lip print patterns, findings remain highly discordant, with no universally accepted correlation between lip characteristics and biological sex [1; 7; 11]. This variability complicates the role of cheiloscopy as a forensic tool, emphasizing the need for standardized and objective methodologies. In contrast, other forensic identification techniques, such as fingerprint analysis and dental profiling, have benefited from advancements in digital and 3D technologies, improving precision, reproducibility, and data management [12; 13]. Cheiloscopy, however, has been slower to adopt similar innovations, remaining reliant on traditional analog methods that are less effective in complex forensic scenarios. The advent of 3D imaging technology presents a transformative opportunity for cheiloscopy. High-resolution optical scanners, such as intraoral devices, enable the capture of detailed three-dimensional representations of the lips, addressing many of the limitations of traditional methods. This approach minimizes operator dependence, reduces artifacts, and improves long-term data storage. Furthermore, 3D cheiloscopy facilitates advanced digital manipulation and interdisciplinary collaboration by enabling the sharing of standardized digital models [14]. By enhancing systematic matching and reducing human error, this technology offers the potential for a robust, standardized digital database for lip print analysis.