Effects of Three Different Orthodontic Treatment Methods on the Stability of Mandibular Incisor Alignment

To compare the effects of extraction, non-extraction and air-rotor stripping treatments on mandibular dental arch dimensions, lower incisor positions and evaluate their effects on the stability of the treatment. Study design: The sample consisted of 44 patients with Class I malocclusion and moderate crowding including 15 patients treated with extraction, 13 with air-rotor stripping (ARS), and 16 with nonextraction treatment. The records were taken at pretreatment (T0), end of active orthodontic treatment (T1), minimum 3 years post-treatment (T2). The model and cephalometric measurements were evaluated. For statistical analyses ANOVA and Welch test was applied. Results: At post-retention period Little’s irregularity indices were increased to 1.96 mm, 2.38 mm and 3.59 mm for extraction, ARS and non-extraction groups respectively (p<0.05). At T1-T2, intercanine widths were decreased significantly at all groups (p<0.05). The arch length and arch depth decreased significantly at extraction group (p<0.05) from T0 to T1 and remained the same at T2 (p>0.05). The lower incisors were retroclined with treatment and slightly proclined at post-retention period in extraction group. In ARS and non-extraction group, lower incisors proclined with treatment and remained the same at post-retention. Conclusion: At all groups the irregularity indices relapsed but did not return to pretreatment values. Although significant increase at intercanine width was only observed in non-extraction treatment, at post-retention phase, intercanine widths were significantly decreased at all groups. The changes at lower incisor inclinations relapsed slightly in extraction group but remained the same in the other groups.

Relapse, Retention, Stability, Extraction vs. non-extraction

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