Relapse of anterior crowding 3 and 33 years postretention.

Introduction: The aim of this study was to evaluate the relapse of occlusal characteristics and maxillary and mandibular anterior crowding 3 and 33 years postretention.

Methods: The sample comprised 28 patients, 15 Class I and 13 Class II, treated with 4 premolar extractions, with a mean initial age of 12.72 years (SD, 0.99), a mean final age of 14.74 years (SD, 1.26), and a mean treatment time of 2.02 years (SD, 0.66). The mean short-term postretention age was 20.15 years (SD, 1.34), and the mean long-term postretention age was 49.40 years (SD, 4.54). The mean time of short-term postretention evaluation was 3.70 years (SD, 0.87) and the mean long-term postretention evaluation was 32.95 years (SD, 4.31). The maxillary and mandibular irregularity indexes were assessed on the initial, final, short-term, and long-term postretention stage dental casts. Peer Assessment Rating and the Little indexes were compared among the 4 stages by repeated measures analysis of variance and Tukey tests.

Results: Peer Assessment Rating index and maxillary anterior crowding were significantly improved with treatment, had significant relapses in the short term, and a slight and not statistically significant increase from short-term to long-term postretention evaluation. The mandibular irregularity index significantly decreased with treatment, and then significantly and progressively increased in the postretention stages.

Conclusions: The occlusal characteristics and maxillary anterior crowding had significant relapses in the short term and remained stable from the short-term to the long-term postretention stages. Mandibular anterior crowding significantly decreased with treatment, showed a significant relapse in the short term, and continued to significantly increase in the long-term postretention stage.