# Comparative Evaluation of Photogrammetric, Radiographic, and Direct Measurements in Facial Analysis: A Cross-Sectional Study

## TL;DR

This study compares photogrammetry, radiography, and direct measurements for facial analysis, finding photogrammetry to be a reliable, noninvasive alternative with some limitations.

## Contribution

The study provides a comparative evaluation of photogrammetry against traditional radiographic and direct methods in facial analysis.

## Key findings

- Photogrammetric measurements showed excellent reliability with ICC values between 0.85 and 0.91.
- Photogrammetry was more accurate in the horizontal frontal plane, while radiography was more accurate in the vertical frontal plane.
- Lateral plane measurements showed good agreement, except for specific parameters like Trg-Sn and Al-Prn.

## Abstract

Introduction: Facial analysis plays an important role in evaluating and planning treatments related to dental, surgical, and forensic applications. Traditionally, cephalometric radiography has been widely used to assess craniofacial structures, providing information on skeletal and dental relationships. Recently, photogrammetry has gained attention as a noninvasive method that utilizes standardized photographs to evaluate facial proportions and symmetry, eliminating radiation exposure. This study focuses on comparing photogrammetric measurements with radiographic and direct measurements to evaluate the accuracy and reliability of photogrammetry for facial analysis.

Materials and methods: This prospective, observational, cross-sectional study was conducted in the Department of Orthodontics and Dentofacial Orthopedics, Amrith Educational & Cultural Society (AECS) Maaruti College of Dental Sciences & Research Centre, Bengaluru, over two years, from September 2020 to July 2022. Fifty participants (18-25 years old) with well-balanced facial profiles were included in this study. Standardized frontal and lateral photographs were obtained under controlled lighting conditions and subject positioning. Cephalometric radiographs were obtained using digital radiography units (DRUs). Direct anthropometric measurements were recorded using a digital Vernier caliper. Eighteen cephalometric landmarks were identified for comparison purposes. Image analysis was performed using image software. Statistical analysis was conducted using Kruskal-Wallis and post hoc Dunn tests to compare the methods. Intra- and inter-examiner reliability was assessed using the intraclass correlation coefficient (ICC).

Results: The ICC values (0.85-0.91) indicated excellent measurement reliability. Photogrammetric measurements were generally higher in the horizontal frontal plane, whereas radiographic measurements yielded higher values in the vertical frontal plane. Lateral plane measurements showed greater agreement among the three methods, except for parameters such as tragon-to-subnasale distance (Trg-Sn) and alar-to-pronasale distance (Al-Prn), which differed significantly between groups.

Conclusion: Photogrammetry is a viable, noninvasive alternative to cephalometry, offering ease of use and radiation-free assessment. However, variations owing to head positioning, lack of depth perception, and minor magnification errors must be considered. Future studies should integrate three-dimensional imaging to enhance its accuracy and clinical applicability.