Cephalometric Evaluation of Lip Strain and Nasolabial Angle Changes Following Orthodontic Treatment with First Premolar Extractions
A Retrospective Study
Abstract
Background: Orthodontics aims to correct malocclusions for improved aesthetics, function, and structural balance. Extraction of teeth, particularly first premolars, is often necessary to gain space for treating crowding, proclination, and sagittal discrepancies. This is especially relevant in cases like bimaxillary protrusion, where extraction enhances facial aesthetics by reducing lip procumbency. Lip strain and nasolabial angle, key considerations in treatment planning, are influenced by incisor retraction. However, the correlation between these factors remains debated across different ethnicities. Aim: To evaluate and compare changes in the nasolabial angle and lip thickness before and after orthodontic treatment in bimaxillary protrusion cases treated with first premolar extractions. Materials: A retrospective cephalometric study was conducted on 50 adult patients with bimaxillary protrusion treated with first premolar extractions. Pre- and post-treatment lateral cephalograms were evaluated. The sample included Angles Class I malocclusion and proclined incisors, treated with pre adjusted edgewise appliances. Lip strain and nasolabial angle were measured using standard cephalometric tracing techniques. Statistical analysis was conducted using a paired t-test. Results: The results showed significant changes in both lip strain and nasolabial angle following orthodontic treatment. Overall, both male and female participants exhibited reductions in lip strain and increases in nasolabial angle, with statistical significance (p<0.05). Lip strain changes were more pronounced in females (p<0.001) compared to males , while nasolabial angle changes were highly significant for both genders (p<0.005).Conclusion: Significant enhancements in nasolabial angle and lip strain were observed following orthodontic treatment, with more pronounced soft tissue changes in female participants.
Keywords : Cephalometrics, Lip strain, Nasolabial angle, orthodontics.
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