Skeletal and dentoalveolar effects of miniscrew-assisted rapid palatal expansion based on the length of the miniscrew: a randomized clinical trial.

Objectives: To compare skeletal and dentoalveolar changes of miniscrew-assisted rapid palatal expansion (MARPE) according to the length of the miniscrews.

Materials and methods: This two-arm parallel-randomized controlled trial included 32 adult patients aged 19-35 years who received orthodontic treatment with MARPE. Patients were allocated to two groups, group long (L) and short (S), through block randomization according to the length of the miniscrews installed in MARPE. Cone-beam computed tomography was performed before expansion and after removal of the MARPE; superimposition of the images was conducted. The primary outcome included the amount of bone expansion and the change in the inclination of the anchorage teeth. The secondary outcome included the success rate of midpalatal suture opening and stability of the miniscrews. Blinding was performed during outcome assessment.

Results: The final sample comprised 31 patients. There was no significant difference in patient characteristics between group L (n = 16) and group S (n = 15). The change in the width of the processus zygomaticus (P = .010) and ectocanine (P = .001) was significantly higher in group L. A significantly higher success rate of the posterior miniscrews was seen in group L (P = .024). There was no statistically significant difference in the success rate of suture separation or change in tooth inclination. Notable complications were not reported.

Conclusions: MARPE with longer miniscrews can increase the amount of expansion of the maxillary basal bone and canine alveolar bone. Although it also aided in miniscrew stability, it did not guarantee successful midpalatal suture separation.