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Facial Plastic and Reconstructive Surgery

Establishing Sex-Dependent Proportions and Angles of the Lower Facial Third

Monday, October 2, 2023
9:27 AM - 9:33 AM East Coast USA Time
Location: 205ABC

    Presenting Author(s)

  • Habib Khoury, MD

    Resident Physician
    University of North Carolina - Chapel Hill, Department of Otolaryngology/Head and Neck Surgery
    Durham, NC, United States

    • Co-Author(s)

  • Sarah M. Russel, MD, MPH

    Resident Physician, Postdoctoral Research Fellow
    University of North Carolina - Chapel Hill, Department of Otolaryngology/Head and Neck Surgery
    Chapel Hill, North Carolina, United States

  • DF

    Dennis O. Frank-Ito, PhD

    Associate Professor
    Duke University, Department of Head and Neck Surgery and Communication Sciences
    Durham, NC, USA

  • RW

    Richard Wetherill, BS

    University of North Carolina Adams School of Dentistry, USA

    • Senior Author(s)

  • EF

    Elda L. Fisher, MD, FACS

    Associate Professor
    University of North Carolina - Chapel Hill, Department of Oral and Maxillofacial Surgery
    Durham, NC, United States

Disclosure(s):
Sarah M. Russel, MD, MPH: No relevant relationships to disclose.
Introduction: Facial Gender Confirmation Surgery (FGCS) is an established option for individuals seeking to pursue modifications to their facial features that better reflect their gender identity. Currently, there are limited studies that highlight the sex-depended differences in bony and soft tissue angles of the lower facial third.

Methods: Adult patients 25 years of age or older with anatomically normal, healthy maxillofacial computed tomography (CT) scans were identified via retrospective chart review. Patients with history of craniofacial pathology, facial fractures, or prior FGCS were excluded. Race, sex at birth, and gender identity were included. Three-dimensional models of the bony skeleton and soft tissue contours were generated from CT scans using Mimics 19.0. The primary outcome of the study was quantifying the bony and soft tissue measurements/angles of the lower third of the face, which included chin width, distance between mandibular angles, width between tragi, geniolabial angles, and acuity of mandibular angles. Wilcoxon rank-sum test was used to assess pairwise differences between sexes.

Results: Fifteen scans (7 male and 8 female) were collected and analyzed. Average age was 49.2 ± 16.9 years and was not significantly different between males and females (p=0.74). Racial distribution among patients featured 5 White, 5 Black, 2 Latine, 1 Asian, and 2 who chose not to disclose. On average, males had wider faces compared to females as measured by tragus to tragus (162.4 ± 8.8 vs 144.6 ± 8.1 cm, p=0.02) and mandibular angle to angle (100.8 ± 2.1 vs 89.5 ± 7.9, p=0.02) distances. The ratio of genial width to mandibular angle-to-angle length was greater in males than females (0.40 ± 0.06 vs 0.31 ± 0.04, p=0.01). The mandibular angle (128.1 ± 6.0 vs 119.1 ± 7.0, p< 0.01) and genial angle (153.8 ± 4.6 vs 141.1 ± 7.1, p< 0.01) were more obtuse in females than in males.

Conclusions: This study adds to the existing literature supporting sex-dependent differences in facial structures, and provides objective measurements to aid in optimizing outcomes and patient satisfaction from FGCS.