Facial asymmetry and midsagittal plane definition in 3D: A bias-free, automated method

Abstract

Symmetry is a fundamental biological concept in all living organisms. It is related to a variety of physical and social traits ranging from genetic background integrity and developmental stability to the perception of physical appearance. Within this context, the study of human facial asymmetry carries a unique significance. Here, we validated an efficient method to assess 3D facial surface symmetry by best-fit approximating the original surface to its mirrored one. Following this step, the midsagittal plane of the face was automatically defined at the midpoints of the contralateral corresponding vertices of the superimposed models and colour coded distance maps were constructed. The method was tested by two operators using facial models of different surface size. The results show that the midsagittal plane definition was highly reproducible (maximum error < 0.1 mm or°) and remained robust for different extents of the facial surface model. The symmetry assessments were valid (differences between corresponding bilateral measurement areas < 0.1 mm), highly reproducible (error < 0.01 mm), and were modified by the extent of the initial surface model. The present landmark-free, automated method to assess facial asymmetry and define the midsagittal plane of the face is accurate, objective, easily applicable, comprehensible and cost effective.

Discrepancies in Cephalometric Analysis Results between Orthodontists and Radiologists and Artificial Intelligence: A Systematic Review

“…Classic orthodontic approaches mostly use a standard lateral cephalometric radiograph to evaluate the patient's profile, bite, and occlusion [1][2][3]. The socalled 3D individual approach for each patient is currently regarded as the method of choice for several reasons [4][5][6][7]. Due to improvements in digital diagnostics, orthodontic treatment is greatly influenced by these advancements.…”

“…Currently, many reports describe improvements in CBCT, 3D imaging, artificial intelligence (AI) usage, and other devices to enhance overall facial and bite diagnostics. These advancements aim to establish the most accurate and up-todate treatment plans for each case of dental and skeletal malocclusions [4][5][6][7]. Due to the numerous papers focusing on computer-enhanced planning and evaluation, it is essential to understand not only the benefits, limitations, strengths, and weaknesses of each classic 2D versus 3D evaluation but also how new techniques can assess the cephalometric image of each patient in computer-assisted and AI-improved studies [7][8][9][10][11].…”