Effect of lip thickness and competency on soft tissue changes in Class I and Class II div 1 malocclusion with 1st pre- molar extraction

Background: Alterations in incisor position during orthodontic treatment modify the soft tissue morphology, including length and thickness of the lip, thereby enhancing the facial profile and esthetics of the patient.Materials and Methods: The study included 60 non-growing individuals. Subjects were divided into 2 groups of 30 participants: Group 1 - Angle’s Class I bimaxillary dentoalveolar protrusion with average horizontal and vertical growth pattern. (n=10 in each growth pattern), Group 2 – Angle’s Class II div 1 malocclusion with average, horizontal, and vertical growth pattern. (n=10 in each growth pattern). Pre and post-treatment lateral cephalograms were used to compare skeletal, dental, and soft tissue profile changes in length and thickness of the upper and lower lips which were correlated with Pre and post-inclination of the upper and lower incisors following treatment of Class I Bimaxillary and Class II div 1 Malocclusion.Results: Regression analysis showed individuals with class I AGP showed a significant decrease in the LUL with retraction of L1 to NB; a significant increase was observed with retraction of L1 to NB in the LUL for VGP. For Class II individuals, a significant decrease in the thickness of the lower lip was observed with retraction of L1 to NB in the average horizontal and vertical growth pattern.Conclusion: Orthodontic treatment leads to significant dentoalveolar changes, especially in incisor positioning, with Class II patients showing more pronounced responses. Soft tissue adaptations vary by growth pattern, with vertical growers exhibiting the most notable changes