INVESTIGATION OF THE ACCURACY OF THE PORIUM-MASTOIDEO DISTANCE FOR SEX ESTIMATION

Abstract

Introduction: Different anatomical bone structures can provide relevant information for the process of human identification in forensic anthropology. Studies have examined the mastoid process for its potential in sexual dimorphism.  Objective: To evaluate the accuracy of sex estimation using the distance between the craniometric points porium (Po) and mastoid (Ma) in identified human skeletons. Methodology: 832 mastoid processes from 416 skulls of individuals of both sexes, aged 20 years or older, were measured using a digital caliper. The inter-examiner and intra-examiner intraclass correlation coefficient (ICC) values obtained were 0.959 and 0.922, respectively. The information was analysed using IBM™ SPSS® software (version 22.0). The Student's t-test for paired samples was applied, and correlations and covariances were evaluated. Logistic regression and ROC curve analyses were performed to obtain information on which variables had the power to estimate sex in the study sample. The significance level was 5% (p≤ 0.05). Results: The Po-Ma distance ranged from a minimum of 18 to a maximum of 40 mm in the right mastoid (mean: 29.13 mm) and from a minimum of 20 to a maximum of 40 mm in the left mastoid (mean: 29.21 mm). In the male group, the averages were 31.12 mm (±3.649) on the right and 31.10 mm (±3.429) on the left. In females, they were 27.05 mm (±3.226) and 27.24 mm (±2.897), respectively. Both right and left mastoid measurements showed the ability to estimate sex, with the left mastoid showing superior independent predictive power. An overall accuracy of 75.5% was obtained, with 76.5% accuracy for females and 74.5% for males. Conclusion: The method showed a good probability of classification for sex, with a slightly higher percentage of correct estimation for females.