Efficacy of Natural Dye (Indigo blue), Lysochrome Dye (Sudan black) and Fluorescent Dye (Nile blue A) in Cheiloscopy as a Lip Print Enhancer in Forensic Odontology: A Cross-sectional Study

Introduction:The study of lip prints is known as cheiloscopy. Lip prints are unique for each individual, which plays a key role in suspect identification. These imprints obtained on any surface may be in visible or latent form. Latent forms of lip prints are difficult to identify; hence various dyes are used to enhance the latent lip prints obtained from different surfaces. The present study has included the both porous and non porous surfaces. It is essential to determine how the surface of an object effects the enhancement efficiency of latent lip prints with different dyes. Aim: To compare the enhancement efficacy among of Indigo dye (Natural dye), Sudan black (Lysochrome dye) and Nile blue A (Fluorescent dye) on porous and non porous surfaces, assessing their applicability in cheiloscopy. Materials and Methods: The present cross-sectional study was carried out on 120 individuals. All the subjects were students from Vishnu Dental College, Bhimavaram, Andhra Pradesh, India. The Lip print collection completed within six months which was started in July 2022 and ended in January 2023. Individuals with age group of 18-25 years were considered. After obtaining informed consent, subjects were asked to make an imprint on the given surfaces like porous and non porous (white and red colour surfaces). They were enhanced immediately by applying Indigo blue, Sudan black and Fluorescent dye for evaluating the clarity of lip grooves. Chi-square test was used to compare the enhancement efficiency among three dyes. The p-value<0.05 was considered as statistically significant. Results: Fluorescent dye has better enhancement than the indigo dye and lysochrome dye with the significant p-value 0.001. When lysochrome dye and Fluorescent dye compared the results were not statistically significant (p-value=0.012). When compared between non porous and porous surfaces better enhancement was observed on porous surfaces predominantly by Fluorescent dye. Conclusion: The present study revealed the usefulness of latent lip print in individual identification in forensic dentistry. Fluorescent dye gives a better positive result than Indigo blue, but when compared with lysochrome dye there was no obvious significance during enhancement.