Correlation Between Volumetric Soft Tissue Asymmetry and Postero-Anterior Cephalometric Measurements in Patients with Skeletal Facial Asymmetry: A Cross-Sectional Pilot Study

TL;DR

This study finds that lower facial soft tissue asymmetry is strongly linked to mandibular skeletal deviations, while midface asymmetry has weaker skeletal correlations.

Contribution

This pilot study is the first to correlate 3D volumetric soft tissue asymmetry with PA cephalometric measurements in skeletal facial asymmetry.

Findings

Menton deviation from the midline shows the strongest correlation with whole facial asymmetry (R2 = 0.630).

Midfacial asymmetry has only moderate skeletal correlations (maximum R2 = 0.186).

Maxillary occlusal cant parameters do not significantly correlate with soft tissue asymmetry.

Abstract

Background/Objectives: While skeletal facial asymmetry is commonly assessed using posteroanterior (PA) cephalometric radiographs, the association between skeletal measurements and volumetric soft tissue asymmetry remains unclear. This study aimed to identify which skeletal parameters are most strongly correlated with soft tissue asymmetry measured using three-dimensional (3D) imaging. Methods: Thirty-three Japanese patients (8 males and 25 females; mean age: 26.85 ± 12.13 years) undergoing orthodontic–orthognathic treatment were included. Three-dimensional facial surface data were acquired using the VECTRA® H1 imaging system. Soft tissue asymmetry was quantified by calculating the volumetric difference between the original and mirrored 3D facial images, divided into three regions: whole face, midface, and lower face. PA cephalometric radiographs were traced, and 28 skeletal variables were measured. Pearson correlation coefficients were calculated between skeletal variables and asymmetry volumes and squared to obtain R2 values. Results: The strongest correlation with whole facial soft tissue asymmetry was found for menton deviation from the midline (R2 = 0.630). Similar trends were observed for the lower face. In contrast, only one skeletal variable showed a moderate correlation with midfacial asymmetry (maximum R2 = 0.186), and skeletal parameters related to maxillary occlusal cant did not show significant associations. Conclusions: Volumetric soft tissue asymmetry is strongly associated with mandibular skeletal deviation, particularly menton displacement, whereas midfacial skeletal morphology may have a limited impact. Further studies including more patients with pronounced midfacial soft tissue asymmetry are warranted.

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