Rertospective comparison of long-term stability of first premolar extraction orthodontic treatment in skeletal cl I and skeletal cl II patients

Abstract

Regarding the basic differences between patient with skeletal class I and skeletal class II facial patterns including soft tissue pressure, mandibular size and position, and growth pattern it can be questioned whether the skeletal pattern influences the amount of relapse or not The purpose of this retrospective study was to compare long-term stability of first premolar extraction orthodontic treatment in skeletal Cl I and Skeletal Cl II patients. Materials and Methods: 28 skeletal Class I samples and 28 skeletal Class II samples were randomly selected. Independent t-test was applied to compare the mentioned variables between the two groups. Results: Class I cases showed greater amounts of Irregularity index at post-retention (2081+-1/08 mm) , more decrease in intercanine width (2/66+-0/081) and arch length (3.01+-1.13) from post-treatment to post-retention period. Positive and direct correlations were found between the amount of pre-treatment irregularity index and irregularity index post-retention. conclusion: Patients with Class I skeletal pattern and greater pretreatment irregularity index are at risk of increased post-treatment relapse of mandibular anterior crowding.