Evaluation of facial soft tissue thickness in symmetric and asymmetric subjects with the use of cone-beam computed tomography

Introduction: The aims of this study were to evaluate facial bilateral soft tissue thickness in symmetric and asymmetric subjects and to investigate whether soft tissue compensates for skeletal asymmetry. Methods: Cone-beam computed tomography (CBCT) scans of 97 subjects were divided into a symmetry group (GSm) and an asymmetry group (GASm). Seven bilateral points were established. Each point involved 3 variables: hard tissue distance (Hard-D), soft tissue distance (Soft-D), and soft tissue thickness (Soft-Th). Measurements were taken from software-generated multiplanar reconstructions. A paired t test was used to assess intragroup differences and an independent t test for intergroup analysis. Pearson coefficient tested correlations between variables. Results: In GASm, significant differences were found in all Hard-D and Soft-D measurements, with higher values observed on the deviated side (P <0.01). As for Soft-Th evaluation, results of only 1 reference point presented statistical significance. Intergroup comparison detected significant differences in all Hard-D and Soft-D variables (P <0.01), but no significant differences in Soft-Th. Conclusions: Asymmetric subjects presented differences in hard and soft tissue distances between deviated and nondeviated sides, although without affecting soft tissue thickness. It can be concluded that soft tissue does not compensate or disguise an underlying skeletal asymmetry.