Authors: Hayder A. Hashim, Najat AL-Sayed, Noof AL-Obaidli, Mohamed Hayder A. Hashim, Feras Abed Al Jawad.
Aim: This study aimed to compare facial groups based on their vertical skeletal characteristics (hypodivergent, normodivergent, and hyperdivergent) and their associated soft tissue features, focusing on the lips and chin.
Materials and Methods: A total of 103 lateral cephalometric x-rays were obtained from patients sought orthodontic treatment. The samples were categorized into hypodivergent (Md/Mx <20°), normodivergent (Md/Mx between >20° and 28°), and hyperdivergent (Md/Mx >28°) facial types.
Results: In Class I group, normodivergent facial type was the most prevalent (55.2%), while hyperdivergent pattern dominated in Class II (54.5%) and Class III (40%) groups. The hypodivergent group exhibited the highest mean thickness for upper and lower lips (8.95 mm and 9.35 mm, respectively). Hyperdivergent individuals had the greatest mean upper lip height (11.3 mm), whereas hypodivergent individuals had the highest mean lower lip height (25.32 mm). Procumbency of upper (PUL) and lower lips (PLL) was most prominent in the hypodivergent group (2.08 mm and 0.87 mm, respectively). Hyperdivergent individuals showed the maximum mean chin thickness (7.84 mm). Statistically significant differences were observed only between Hypo vs Normo-divergent groups in upper lip thickness (ULT), and in PUL and PLL between Hypo vs Normodivergent and Hypo vs Hyperdivergent groups.
Conclusion: The study concluded that a correlation between the hard tissue (bones and teeth) and soft tissue (facial features) topography were found in Sudanese subjects. There was a significant correlation between the soft tissue variables including nasolabial angle, upper lip thickness, and length in the three different skeletal vertical dimensions, but this correlation was observed only in the lower jaw. Individuals with hypodivergent facial patterns tend to have greater thickness in the upper and lower lips, lower lip height, compared to normodivergent and hyperdivergent counterparts.