Relapse of anterior crowding 3 and 33 years postretention

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

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.

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.

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.