Orthodontic Forces Interrupt Root Formation in Immature Teeth: Myth or Fact? A Pilot Study

To assess the effects of rapid maxillary expansion (RME) and orthodontic treatment with fixed appliances on the developing roots of anchor teeth compared with completely formed roots.

Pre- and post-treatment cone-beam computed tomography (CBCT) scans of 19 patients (mean pre-treatment age 10.9±1.3, mean post-treatment age 13.66±1.29) with incompletely formed roots who had undergone RME and orthodontic treatment with fixed appliances were selected. In addition, 15 CBCT scans of age- and sex-matched untreated controls (mean age 13.69±1.08) with completely formed roots of the same teeth were obtained. Pre- and post-treatment CBCT records of the experimental group were segmented and reconstructed to obtain linear and volumetric measurements of the roots for comparison with the control group. Changes in the root dimensions were analyzed using the paired t-test; Independent Student's t-test was used for comparisons between the groups.

All premolars in the experimental group showed a statistically significant increase in root length and volume post-treatment (p<0.05), with the greatest increase seen in the second premolar. The distobuccal and palatal root lengths of the molars decreased significantly after treatment in the experimental group. The comparison of post-treatment root dimensions between the experimental and untreated control groups showed no significant difference.

The teeth with developing roots attain normal root length after RME and orthodontic treatment with fixed appliances, with no significant differences in root length and volume compared with teeth with completely formed roots.