Comparative evaluation of perioral soft tissue of skeletal normal Class I and Class II Division 1 subjects: A lateral cephalometric study

Objective: This study aimed to evaluate and compare shape variability of soft-tissue outline of skeletal Class II Division 1 patients with various vertical patterns (low, moderate, and high SN-MP angles) and skeletal normal Class I occlusion patients and to evaluate correlative skeletal and dental variables affecting soft-tissue thickness using cephalometric analysis. Materials and Methods: Sixty patients were selected with Class I normal occlusion and Class II Division 1 and divided into four groups based on horizontal and vertical skeletal pattern (SN-MP angles) on lateral cephalograms as Group I (normal occlusion), Group II-L (low angle <27<degrees>), Group II-N (normal angle 27 degrees -36 degrees), and Group II-H (high angle >= 37 degrees). The correlation and multiple linear regression analysis were used to determine skeletal and dental variables influencing soft tissue characteristics. Results: The skeletal Class II patients with a high mandibular plane angle had significantly greater values than the skeletal Class II patients with a low mandibular plane angle for basic lower lip thickness and lower lip length. The measurements in perioral soft-tissue thickness were correlated with an inclination of the upper and lower incisors along with facial depth and facial length in skeletal Class II Division 1 patients. Conclusion: Lip strain, lip thickness, and dental inclination must be evaluated based on various skeletal patterns for balanced perioral muscle activity.