Tongue prints as an emerging biometric tool in forensic odontology: a systematic review

Abstract Background Tongue prints have recently emerged as a promising biometric trait in forensic odontology. Their unique surface morphology, protection from external factors, and long-term stability position them as potential identifiers in forensic investigations. Despite these advantages, research on tongue prints remains limited, with inconsistencies in methodology and classification. This systematic review aimed to evaluate the forensic reliability of tongue prints as a biometric identifier and to compare their performance with established oral markers, particularly palatal rugae. Main text A comprehensive search of four databases covering the period 2015–2025 identified 1,886 records, of which six studies met the inclusion criteria. Together, these studies analyzed 826 participants using visual inspection, digital imaging, or lingual impression techniques. All studies consistently demonstrated that tongue prints exhibit individual uniqueness and morphological stability over time. Findings also indicated sex- and age-related variations in tongue morphology, while correlations with blood group were inconsistent. The comparison between tongue prints and palatal rugae suggested comparable discriminatory potential and forensic relevance. Nevertheless, most studies were geographically restricted to India and displayed methodological heterogeneity, including differences in image acquisition and classification systems, which limit the generalizability of the evidence. Despite these limitations, the reviewed literature highlights the potential of tongue prints to serve as reliable biometric markers when supported by standardized protocols and digital analytic methods. Conclusions Tongue prints appear to be a stable, non-invasive, and reproducible biometric modality that could complement established forensic identifiers. Their integration with other oral features such as palatal rugae and dental records may enhance personal identification accuracy, particularly in cases involving decomposed or unrecognizable remains. To establish global applicability, future research should emphasize standardized classification methods, examiner calibration, and inclusion of multi-ethnic populations, while leveraging emerging technologies such as digital imaging and artificial intelligence for improved precision in forensic identification.