Association of antegonial notch size with craniofacial morphology and masticatory muscle dimensions

Abstract

The antegonial notch (AGN) is a structure that has been variably described across studies, with diverse findings regarding its role and association with craniofacial morphology, which is attributed to differing methodologies and the lack of control for sex and size. This study aimed to elucidate the variability of the AGN and examine its association with facial types, skeletal and muscular parameters. This study was carried out using the CT scans of 311 individuals aged 18-95 years. Facial type, skeletal and muscular measurements were recorded. Mann-Whitney and Kruskal-Wallis tests were conducted to examine AGN area differences between the sexes and facial types. Spearman correlation was used to explore the relationships between AGN and the skeletal and muscular parameters. AGN was found to be sex dependent: it was absent in 22.7% of males and 35.1% of females; its size was larger in males than in females (55 mm² vs. 31 mm²) (p < 0.001). The AGN area did not vary between the facial types (p > 0.073). Its size showed weak correlations with skeletal parameters and no associations with masticatory muscles (p > 0.375). Our findings indicate that the AGN is more prevalent and pronounced in males, and that there was no evidence of a functional relationship.

Keywords: Antegonial notch; Facial growth; Facial types; Mandibular morphology; Masticatory muscles; Sex.

Fig. 1

Measurement method for the AGN area (the light blue area). The notch is bordered between the lower rim of the mandibular body and the mandibular plane. Anatomical landmarks defining the notch area: (A) the anterior limit of the notch, (B) the posterior limit of the notch, and (C) the peak of the notch. The volume rendering technique was utilized to create the shape of the mandible.

Fig. 2

Prevalence of AGN in males and females.

Fig. 3

The AGN area in males and females with AGN (area ≥ 2 mm²). (a) Absolute measures, (b) corrected measures. p^a represents the p-value for absolute area size; p^c represents the p value for the corrected area size.

Fig. 4

The prevalence of AGN by facial type. LFT long facial type, AFT average facial type, SFT short facial type.

Fig. 5

The AGN area size (absolute measures) by facial type and sex in individuals with AGN. p^M represents the statistical difference between facial types in males; p^F represents the statistical difference between facial types in females, and p^{M vs F} represents the statistical difference between the sexes in each facial type. LFT: Long Facial Type, AFT: Average Facial Type, SFT: Short Facial Type.

Fig. 6

The AGN area size (corrected measures) by facial type and sex in individuals with AGN. p^M represents the statistical difference between facial types in males; p^F represents the statistical difference between facial types in females, and p^{M vs F} represents the statistical difference between the sexes in each facial type. LFT: Long Facial Type, AFT: Average Facial Type, SFT: Short Facial Type.