LAUSR

Abstract Objective The aim of this study was to compare the treatment times in cases treated with extractions with mild and severe crowding. Design and Setting Anterior crowding of 150 Class I malocclusion cases, treated with four first-premolar extractions, was measured with Little's Irregularity Index (LII). After excluding the cases with moderate maxillary LII (middle quartiles), the remaining 74 cases were divided into mild crowding (mean age 13.94 years, 14 male, 23 female) and severe crowding (mean age 14.69 years, 17 male, 20 female) groups, with 37 individuals each (LII smaller than 7.83 m and greater than 12.18 mm, respectively). Methods Anterior crowding was digitally measured in digitized dental casts. The groups were matched regarding sex, initial age, and Objective Grading System index. Results Treatment time was statistically similar between both groups. However, there was significantly shorter treatment time in patients with extreme maxillary incisor irregularity (18.34 mm) as compared with patients with insignificant maxillary incisor irregularity (5.50 mm). Conclusion Treatment times of Class I malocclusions with mild and severe crowding, treated with four first-premolar extractions are similar.