Stability of extraction space closure

•Extraction space reopened in about 30% of the subjects by 5 years.•Most of the reopening occurred in the first year after treatment.•Space reopened in patients with less anterior crowding and more mandibular incisor retraction.

IntroductionThe objectives of this study were to evaluate the prevalence and long-term behavior of extraction space reopening in patients with Class I malocclusion and to identify some associated factors.MethodsA sample of 43 patients met the inclusion criteria. Dental casts at the onset of treatment, after treatment, and 1 and 5 years after debonding were used. Initial and final cephalometric radiographs were used to measure the amount of incisor retraction. Cochran tests were used to compare the numbers of open and closed extraction spaces after treatment and at 1 and 5 years after debonding (P <0.05). Initial incisor crowding, amounts of anterior retraction, and angulations between the canines and the second premolars were compared between patients with and without space reopening with t tests.ResultsOf the sample, 30.23% had extraction space reopening. The frequency of open spaces significantly increased between the final and the 1-year posttreatment dental casts and decreased between the casts at 1 and 5 years posttreatment. Patients with space reopening had less initial anterior crowding and greater amounts of mandibular incisor retraction during treatment.ConclusionsThere was a high prevalence of space reopening 1 year after treatment. However, these spaces tended to decrease by 5 years after treatment.