Does lip change following premolar extraction differ in patients with high and normal vertical growth patterns?

Objective: To evaluate the relationship between incisor retraction and upper and lower lip repositioning in patients with high and normal vertical growth patterns (NVP), and to assess whether vertical growth pattern influences soft tissue changes following extraction treatments. Methods: Pre- and post-treatment lateral cephalograms of 79 patients who underwent extraction of two or four first premolars were analyzed. Patients were divided into a [high vertical pattern (HVP); Frankfort-mandibular plane angle (FMA) >30°, n=49] and a NVP; 22< FMA ≤30°, n=30) group. Horizontal and vertical changes in the lips, labiomental fold, and lip strain were measured, and correlations between these changes and incisor movements were assessed. Results: Upper lip retraction was greater in the HVP group (2.86 mm, p<0.05) than in the NVP group (1.97 mm, not significant). Upper lip height decreased significantly in both groups, with a slightly greater decrease in the NVP group (p<0.001). Upper lip strain decreased in both groups, especially in the HVP group (p<0.001). Incisor retraction was strongly correlated with upper-lip changes in both groups, and with lower-lip and labiomental-fold repositioning in the NVP group. Conclusion: Soft tissue response to incisor retraction varies with vertical growth pattern, with greater upper lip retraction in HVP patients. Vertical growth patterns should be considered for optimal soft tissue outcomes.