Definitions of frontal bone inclination: Applicability and quantification.

Area of Science:

• Forensic anthropology
• Osteology
• Biometrics

Background:

• Sex determination from skeletal remains is crucial in forensic anthropology.
• Cranial morphology, specifically forehead shape, is a traditional indicator of sex.
• Existing definitions of frontal bone inclination lack standardization, hindering reliable sex estimation.

Purpose of the Study:

• To evaluate the efficacy of ten different frontal inclination definitions for sex estimation.
• To identify the most accurate and reliable method for quantifying frontal bone inclination in virtual crania.
• To introduce custom software for automated and efficient measurement of cranial angles.

Main Methods:

• Analysis of 211 virtual crania derived from postmortem CT data.
• Automated measurement of ten frontal inclination angles using custom-developed software on 3D cranial images.
• Application of discriminant function analysis to assess sex classification accuracy.

Main Results:

• Four of the ten evaluated frontal angle definitions proved highly significant for sex determination.
• Three definitions demonstrated satisfactory intra- and inter-observer reliability.
• The frontal angle according to Schwalbe yielded the highest accuracy rate (75.4%) with a critical discriminatory value of 88.6°.

Conclusions:

• The Schwalbe angle definition is a reliable and accurate metric for sex estimation in forensic osteology.
• The developed open-source software facilitates rapid, automated, and valid measurement of cranial angles.
• This methodology offers a standardized approach to quantifying frontal bone inclination for improved sex determination.