Distribution and Association of Lip Print Patterns with Dental Diastema in University of Port Harcourt Students

Abstract

Lip prints are unique patterns formed by the grooves on the labial mucosa and have been widely recognised as valuable tools in forensic identification and sex determination. Midline and other types of diastema, representing spacing between teeth, are also considered distinctive features in dental anthropology and forensic investigations. The present study aimed to examine the distribution of lip print patterns in relation to diastema types and to explore potential associations with sex. A cross-sectional study was conducted among 500 students of the University of Port Harcourt, comprising 301 females and 199 males. Lip prints were recorded and classified according to Suzuki and Tsuchihashi’s method into five types (I–V), while diastema was categorised as mandibular, maxillary, or combined. Data were analysed using descriptive statistics and chi-square tests to determine associations between variables. The results revealed that in females, type I lip print was most prevalent (68.44%), while in males, type II (48.74%) and type III (38.69%) predominated. Maxillary diastema was more common in both sexes, with mandibular diastema being rare. Chi-square analysis indicated a significant association between lip print type and diastema category in males (χ² = 21.321, p < 0.05), but not in females (χ² = 11.528, p > 0.05). Additionally, a significant relationship was observed between sex and lip print type (χ² = 286.68, p < 0.05), confirming sexual dimorphism in lip patterns. In conclusion, lip prints demonstrate sex-specific distribution and, in combination with diastema patterns, may serve as reliable adjuncts for human identification and sex determination in forensic and anthropological contexts. These findings underscore the potential utility of cheiloscopy and dental morphology as complementary tools in forensic investigations.