Cephalometric Evaluation of Soft Tissue Changes with Extraction of all First Premolars among the Patients having Bimaxillary Protrusion Attending in the Orthodontics Department of BSMMU

Abstract

Background: Bimaxillary protrusion is a common dentofacial deformity characterized by proclined incisors and prominent lips. While premolar extractions are frequently used for correction, comprehensive cephalometric evaluation of soft tissue changes remains essential for evidence-based treatment planning. Objective: This study aimed to evaluate soft tissue changes following the extraction of all first premolars in bimaxillary protrusion patients undergoing orthodontic treatment at BSMMU’s Orthodontics Department. Methods: A prospective analytical study was conducted on clinically diagnosed bimaxillary protrusion cases. Pre- and post-treatment cephalometric radiographs were analyzed using standardized tracings, assessing six parameters: upper incisor position (U1-APog), lower incisor position (L1-APog), lower anterior face height, upper lip position (UL-E), lower lip position (LL-E), and nasolabial angle (NLA). A single operator performed all measurements to minimize bias. Paired t-tests compared pre- and post-treatment changes (p<0.05 considered significant). Results: Significant retraction of the upper lip (mean 3.58 mm, p<0.001) and lower lip (mean 1.83 mm, p<0.001) was observed. The nasolabial angle increased by 8.59° (from 81.07° to 89.67°, p<0.001). Lower anterior face height showed minimal change (1.21 mm). All soft tissue improvements were statistically significant (p<0.001). Conclusion: Extraction of the first four premolars effectively reduces soft tissue procumbency in bimaxillary protrusion, with significant improvements in lip position and nasolabial angle. These findings support this treatment approach for enhancing facial profile aesthetics. Early cephalometric assessment should be incorporated into orthodontic planning for such cases.