Development of a sex-predicting nomogram based on temporal bone processes measurements using 3D cone beam computed tomography in an Egyptian population sample

Abstract

Abstract Background Sex determination is the first step in identifying human remains, as it can reduce the number of possible subjects in human identification processes by approximately 50%. The temporal bone processes have a high discriminatory function for sex identification. This cross-sectional study aimed to evaluate the accuracy of morphometric measurements of the temporal bone processes (mastoid, styloid, and zygomatic process) using a three-dimensional cone beam computed tomography for identifying sex in an Egyptian sample. It was conducted on 220 3D CBCT scans (110 males and 110 females) aged 16–92 years. Eleven parameters were measured, and their values were subjected to statistical analysis to detect their association with the participants’ sex. Inter- and intra-observer reliability was assessed using intraclass correlation coefficients and Cohen’s kappa coefficient. Results The present study found that all measured parameters, as well as complete left styloid ossification, were significantly higher in males compared to females. However, no significant difference was observed in the right styloid length and right styloid ossification between both sexes. The univariate logistic regression analysis revealed that all measurements except the styloid length and complete styloid ossification on the right side were significant independent predictors of male sex. The proposed final regression model for sex prediction was as follows: logit(p) = -54.630+(0.508× left mastoid length) +(0.128× inter-mastoid diameter) + (0.140×left styloid length) + (0.135×inter-styloid diameter) + (0.512× right zygomatic width) + (0.138× inter-zygomatic diameter). This model exhibits high discrimination power for predicting the male sex with substantial calibration. The left mastoid length had the highest individual discriminatory power for male sex identification (AUC = 0.897). Conclusion The temporal processes measurements exhibit sexual dimorphism, where all parameters were significantly increased in males compared to females, except the styloid length and complete ossification on the right side. Sex identification of adult Egyptians can be effectively determined through the proposed equation derived from the temporal bone processes parameters. Further external validation on a larger sample size from different Egyptian governorates is necessary to support our results. Incorporating a variable-based nomogram model in forensic settings is recommended to allow quick and direct sex interpretation without complex calculations.