Relapse of anterior crowding after retention phase is one of the major concerns in orthodontic treatments. The Goal of this study was to make a comparison between two groups of subjects to mandibular anterior crowding treatment in the amount of relapse after treatment; the one with premolar extraction and another without any extraction.
Methods:
In this historical cohort study design, mandibular study casts of 40 patients with ClassI and ClassII division1 Angle mal-occlusion treated using edgewise appliances (21 in ext group and 19 in non-ext group) were evaluated in three periods of time: pre-treatment (T1), immediately after active treatment (T2), and post-retention (T3). Statistical analysis was made by paired t test and student t test between T1 & T2 and T2 & T3 further to descriptive statistical measurements.
Results:
The mean initial irregularity index was 7.23mm in Ext group and 6.13mm in Non-ext group that decreased to 0mm with treatment and increased 2.63mm in Ext group and 1.65mm in Non-ext group at T3 which was not statistically significant (p< 0.001). In both groups inter-canine width increased in T2 and decreased at T3 which were statistically significant (p<0.001). Inter-molar width and Arch length decreased in T2 and at T3 in Ext group, and increased in T2 and decreased at T3 in Non-ext group which were statistically significant (p<0.001)
Conclusions:
Ext and Non-ext treatments have similar tendency to relapse and no correlation was found between any variables studied and prediction of mandibular incisor irregularity relapse in the long term.