Dental, skeletal, and soft-tissue changes in adult orthodontic patients treated with premolar extraction and nonextraction: A cross-sectional study

Introduction: Various treatment modalities exist to improve and correct Class I malocclusion. This study evaluated the dental, skeletal, and soft-tissue changes in patients treated by premolar extraction (PME) and nonextraction. Methods: A cross-sectional study was conducted, including subjects ideally planned for PME. Pretreatment and posttreatment lateral cephalograms were compared among the 2 groups. The American Board of Orthodontics Objective Grading System (ABO-OGS) was used to score the posttreatment casts, and soft-tissue profile silhouettes were judged by a panel of orthodontists to evaluate the improvement among the 2 groups. Comparisons between the 2 groups were performed using the Mann-Whitney U test. Spearman correlation was used to study the correlation between the assessment methodologies. Results: Highly significant differences were observed between the 2 groups for ABO-OGS scores (P ≤0.001) and profile silhouette assessment (P ≤0.001). Compared with posttreatment cephalometric readings, highly significant differences were seen for the dental variables: SN-U1, IMPA, and interincisal angle (P ≤0.001). Statistically significant differences were seen for all soft-tissue cephalometric variables. Highly significant moderate to negative correlation (r = −0.410, P ≤0.001) was seen between profile silhouettes and ABO-OGS alignment scores. Highly significant strong negative correlation (r = −0.642, P ≤0.001) was seen between profile silhouettes and the lower lip. Conclusion: Dental and soft-tissue changes were highly significant and were found to be in the ideal range when treated with PME. However, PME and nonextraction treatment modalities did not significantly affect the skeletal parameters as seen on the lateral cephalogram.