Comparisons of soft tissue chin thickness in adult patients with various mandibular divergence patterns

Introduction: Soft tissues define the limits of orthodontic treatment and are the main determinant of objectivity in treatment planning and diagnosis according to the soft tissue paradigm. Hence the objective of this study was to determine soft chin thickness in a sample of Peshawar population in different mandibular divergence patterns. Material and Methods: A total of 95 pre-treatment lateral cephalograms of adult patients (39 males and 56 females) were included in this study. The soft tissue chin thickness was measured at anatomical land marks including; bony pogonion (Pog) and its horizontal projection (Pog’) over the vertical passing through soft tissue pogonion (pog’), distance between bony gnathion (Gn) and soft tissue gnathion (Gn’) and distance between bony menton (Me) and its vertical projection (Me’) on the horizontal passing through soft tissue menton. Results: Age was not statistically significantly different between males or females across the four groups or between men and women within each of the four groups. All soft tissue chin (STC) thicknesses had the highest measurements in the hypodivergent group (L) and gradually decreased across the groups the lowest being in the hyperdivergent group (H). Statistically significant differences were found only for Gn-Gn’ across groups, i.e. in men between low and high angle (P =0.022) and medium-low and high (P =0.039); in women between low and high (P = 0.036). Conclusions: Soft tissue thickness measurements were lesser in patients with hyper-divergent vertical patterns when compared with patients with clinically normal and hypo-divergent vertical skeletal patterns. All STC measurements were greater in men than in women. STC thickness in hyperdivergent pattern should be considered differently at its most anterior point (Pog) relative to its inferior landmarks (Gn and Me).