Influence of body mass index on facial soft tissue morphology in growing non-obese children.

BACKGROUND: Recognizing the relationship between body mass index (BMI) and facial morphology is essential for orthodontic treatment planning, as children with higher BMI often display accelerated growth and larger pre-pubertal facial dimensions. This study explores the relationship between BMI and facial soft tissue morphology in a sample of growing non-obese children. METHODS: Facial soft tissues of 113 elementary school students [55 boys; mean age = 11.8 years, standard deviation (SD) = 1.9] were captured using three-dimensional stereophotogrammetry. BMI was calculated from measured height and weight. Geometric morphometric analysis was performed using 14 fixed landmarks and 400 semilandmarks, which were slid to minimize bending energy between individual meshes and the sample average, ensuring homology. Generalized Procrustes analysis and principal component analysis were conducted to evaluate facial size and shape. Multivariate multiple regression models were employed to assess the relationship between BMI, age, and facial characteristics. RESULTS: The cohort had an average height of 155 cm (SD = 11.8), weight of 46.5 kg (SD = 13.3) and BMI of 18.9 (SD = 3.4). No significant sexual dimorphism in facial dimensions was identified (P = .07). Four principal components (PCs) contributed over 5% of variance: PC1 (27.3%), PC2 (19.9%), PC3 (9.1%), and PC4 (6.1%). Neither BMI nor age showed a significant correlation with centroid size (a proxy for facial size; P = .209). Regression models using PC1-PC4 as outcome variables and BMI and age as predictors demonstrated no significant effect of these variables on facial shape (P > .05 across all models). The study primarily included children prior to their growth spurt. CONCLUSIONS: In non-obese, developing children, BMI, age, and sex were not significantly associated with facial size or shape. It means that BMI alone may not be a sufficient predictor of facial dimensions in children within this age and maturational range.