Prevalence of extraction space reopening in different orthodontic treatment protocols

Introduction In this study, we aimed to compare the amount and frequency of extraction space reopening after 2- and 4-premolar extraction treatments in Class II and 4-premolar extractions in Class I malocclusion patients. Methods The sample comprised 105 subjects with full-cusp Class II and Class I malocclusions, divided into 3 groups. Group 1 consisted of 33 full-cusp Class II malocclusion patients treated with a 2-premolar extraction protocol. Group 2 had 34 full-cusp Class II malocclusion patients treated with 4-premolar extractions, and group 3 included 38 Class I malocclusion patients treated with 4-premolar extractions. The Peer Assessment Rating index was used to assess initial malocclusion severity and quality of the occlusal outcome, measured on dental casts. The amounts of extraction spaces were measured with a digital caliper on the final and long-term posttreatment dental casts, after an average of 9.79 years posttreatment. Intergroup comparisons were performed by analysis of variance, followed by Tukey tests and chi-square tests. Results There were no significant differences regarding the amount and frequency of extraction space reopening among the groups. Conclusions Two- and 4-premolar extractions in Class II and 4-premolar extraction treatment in Class I malocclusion patients show similar reopening of extraction spaces in the long term.