Dental and soft tissue changes following extraction of second premolars in females with bimaxillary protrusion: A retrospective study

Background: Bimaxillary protrusion is a condition wherein esthetic concerns are the main reason behind seeking orthodontic treatment. Aim: The aim of this retrospective cephalometric study was to evaluate the soft tissue profile and dental changes among female Saudi bimaxillary protrusion patients treated with extraction of all second premolars followed by retraction of the anterior teeth. Subjects and Methods: Pre and posttreatment cephalometric radiographs of adult female patients (ages 18-30 years) who underwent orthodontic therapy for Class I bimaxillary protrusion were obtained. Data were analyzed with SPSS^®software. A paired t-Test and Pearson's correlation coefficients were conducted with the statistical significance set at 95% (P value < 0.05). Results: At posttreatment, there was an overall decrease in the mean values among the majority of the soft tissue and dental cephalometric angles and linear measurements. Among soft tissue variables, there was a marginal increase in the upper lip length by 1.49 mm (P < 0.001), and the nasolabial angle increased markedly by 7.64° (P < 0.001). Similarly, a marked increase in retroclination by 5.95° (P < 0.001) was observed among the dental variables. Conversely, no significant changes were noted in the lower incisors. Pearson's correlation analysis revealed a significant correlation between all the different dental variables. Within the soft tissue variables, there was a significant positive correlation between changes in the upper lip protrusion, lower lip protrusion, upper lip thickness, and the distance from the upper and lower lips to the S-line.