Identifying Three-Dimensional Facial Fluctuating Asymmetry in Normal Pediatric Individuals: A Panel Assessment Outcome Study of Clinicians and Observers

Abstract

This study measured three-dimensional facial fluctuating asymmetry in 600 normal and healthy Taiwanese individuals (6 to 12 years old) and assessed the perceptions of increasing levels of facial fluctuating asymmetric severity by using a panel composed of 20 clinicians (surgical professionals), as well as 20 adult and 40 pre-adolescent observers. On average, this normal cohort presented a facial fluctuating asymmetry of 0.96 ± 0.52 mm, with 0.52 ± 0.05, 0.67 ± 0.09, 1.01 ± 0.10, and 1.71 ± 0.36 mm for levels I, II, III, and IV of severity, respectively. For all categories of raters, significant differences in the average symmetry–asymmetry scale values were observed, with level I < level II < level III = level IV (all p < 0.01, except for level III vs. IV comparisons with p > 0.05). For level I, pre-adolescent observers presented a significantly (p < 0.05) higher symmetry–asymmetry scale value than adult observers, with no significant (all p > 0.05) differences for other comparisons. For overall facial asymmetry and levels II, III, and IV, no significant (all p > 0.05) differences were observed. This study reveals that the normal pediatric face is asymmetric and the panel assessment of facial fluctuating asymmetry was influenced by the level of severity and the category of raters and contributes to the literature by revealing that pre-adolescent raters present a similar or higher perception of facial asymmetry than adult raters.

Outcome of facial contour asymmetry after conventional two-dimensional versus computer-assisted three-dimensional planning in cleft orthognathic surgery

“…Furthermore, we exhibited that even the included normal individuals presented with a certain degree of facial asymmetry as revealed by both the 2D and 3D photogrammetric methods. As this finding has widely been demonstrated for normal populations 34,46 , valid deductions could be made from normal-related comparisons. Different from mid-face or nasolabial measurement-based outcome investigations 35,36,47 , in this study we addressed particularly the lower face region.…”

“…For appraisal of facial contour asymmetry outcomes, two varieties of facial soft tissue images were employed in patients and normal individuals. Pre-and post-OGS standardized 3D facial images acquired using the 3dMD system (3dMD LLC, Atlanta, GA, USA) under standard conditions (a permanent installation with fixed ambient lighting and system and fixed individual positioning, including individuals with a natural head position, relaxed facial positioning, a closed mouth, and a thin elastic nylon cap to keep the hair away from the face) 34,35 were used for objective assessment of 3D-based facial contour asymmetry analysis with quantitative and qualitative appraisal of data.…”

“…It revealed that a higher number of 2D planning-guided OGS-treated patients had RMSD values above the threshold value that could be detected in clinical evaluation. A combination of patients' desires and professionals' judgements have been considered important in decision-making process for surgical correction of asymmetries considered "borderline" with values close to the discriminative threshold 7,34 . However, in severe asymmetries (most perceptible), the decision for treatment is usually simple with higher indication for surgical management [1][2][3]15,16,18,30 .…”

“…Historically, the facial asymmetry was mainly appraised using 2D radiograph or photography-guided landmark comparisons [21][22][23] . However, these tools may have underestimated the spatial 3D composition of the face, a complex structure with distinct anatomical components and contours [34][35][36] . Nowadays, 3D photogrammetry is considered an especially preferred tool for facial soft tissue analysis [34][35][36] .…”

“…However, these tools may have underestimated the spatial 3D composition of the face, a complex structure with distinct anatomical components and contours [34][35][36] . Nowadays, 3D photogrammetry is considered an especially preferred tool for facial soft tissue analysis [34][35][36] . We are not aware of any comparative study of 2D and 3D planning modalities focused on soft tissue-based facial contour asymmetry outcome analysis using 3D photogrammetric tool.…”