The aim of this study was to compare dental arch-width and perimeter changes in patients with borderline Class I occlusion, treated with extractions or without extractions with air-rotor stripping (ARS).
The study was conducted with 26 sets of pretreatment and posttreatment dental models of patients with borderline Class I occlusion. Thirteen patients (mean age, 18.1 +/- 3.7 years) were treated with 4 premolar extractions, and 13 (mean age, 17.8 +/- 2.4 years) were treated without extractions but with the ARS technique. Mean maxillary and mandibular crowding values were 5.7 +/- 1.5 and 5.9 +/- 1.4 mm in the extraction group, and 5.0 +/- 1.3 and 5.9 +/- 1.3 mm in the nonextraction group, respectively. A digital caliper was used to measure maxillary and mandibular intercanine and intermolar arch widths and arch perimeters. The Wilcoxon test was used to evaluate treatment changes in each group. The Mann-Whitney U test was used to compare the pretreatment and posttreatment values and the treatment changes between the 2 groups.
At the start of treatment, the maxillary and mandibular intercanine and intermolar widths and the arch perimeters of both groups did not differ statistically. The maxillary intercanine widths were maintained in both groups. The maxillary and mandibular intermolar widths and arch perimeters decreased in the extraction group. In the nonextraction group, intermolar widths decreased, but arch perimeters did not change significantly. After treatment, the maxillary and mandibular intercanine widths were not different between the groups.
In Class I borderline patients with moderate crowding, extraction therapy with minimum anchorage did not result in narrower dental arches, and nonextraction treatment with ARS preserved the intercanine arch widths and arch perimeters.