Effective of Nonextraction Orthodontic Treatment of Angle Class I Malocclusion: A Nonrandomized Pre–post Interventional Study

Introduction: We aimed to evaluate the effectiveness of nonextraction orthodontic treatment for Angle class I malocclusion. Methods: A nonrandomized pre–post interventional study was conducted on patients diagnosed with Angle class I malocclusion, crowding (≤9 mm), and instructed for nonextraction orthodontic treatment. The weighted PAR (Peer Assessment Rating) Index is employed to determine the outcome of orthodontic treatment. Also, soft tissue and bone indexes were assessed before and after intervention. Data were analyzed by linear regression and T -test statistical test using R software version 4.3.0 by a blinded statistician. Results: Thirty-three participants (mean age: 20.5 ± 0.5, 75.6% female) completed the intervention and were included in the analyses. Linear regression showed there was a significant difference between before and after intervention regarding the weighted PAR Index ( p < 0.001). Conclusion: It was possible to complete orthodontic treatment with nonextraction. For cases of minor malocclusion and generally symmetrical characteristics, nonextraction orthodontics was recommended.