Sex estimation using direct gonial angle measurement in 16-24 years old Indonesian population

Introduction
Sex determination has an important role in post-mortem (PM) profile reconstruction, which enables to reduce the possibility of identification. Gonial angle (GA) of mandible is a reliable sex parameter through skeletal examination. However, given frequent limited resources in forensic setting, direct GA measurement approach on deceased’s body is more practicable.

Objectives
This study aims to evaluate GA discriminative ability in sex estimation by using direct measurement method in 16-24 years old Indonesian population.

Material and methods
One hundred individuals (M = 43, F = 57) between 16-24 years old from Jepara District, Central Java, Indonesia, were selected for the measurement of both left (LGA) and right (RGA) gonial angle using a goniometer. Inter-and intra-observer reliability were 0.906 and 0.936, respectively, after one month using intra-class correlation coefficients (ICC). Measured LGA and RGA from males and females were compared using Mann-Whitney U-test, and Pearson’s correlation between LGA and RGA were calculated. Binary logistic regression and ROC curve models were applied to analyze GA capability in sex discrimination.

Results
There was no significant difference between LGA and RGA measurements, and a high correlation was detected (r = 0.73). Both LGA and RGA had significant value to predict sex. AUC value of LGA was 0.615 (p = 0.048; 95% CI: 0.51-0.73) and RGA was 0.637 (p = 0.015; 95% CI: 0.53-0.74).

Conclusions
The proposed direct examination method of GA to predict sex shows a low discriminating performance on both LGA and RGA variables.