Maxillary and Mandibular Arch Response to RME: a Multicentric Randomized Controlled Trial

The effects of rapid maxillary expansion (RME) on the maxillary complex have been highly investigated,4 reporting a maximum maxillary intermolar and intercanine width increase of 6.7 mm and 5.3 mm,5 respectively, when RME is banded on upper first permanent molars. Literature also reported cases of periodontal and endodontic damage on RME anchoring teeth; therefore, some authors have suggested banding RME on primary teeth and reporting also different mean intermolar (3.6-4.1 mm) and intercanine width increases (5-5.9 mm). Few studies have investigated the changes in molar dental tipping and inclinations (on average from 3° up to 16.7°) following RME but comprised difficult (ie, barium sulfate solution) and more invasive examinations such as computed tomography and cone beam computed tomography (CBCT) Few articles concerning the indirect effects on mandibular arch following RME reported a low but statistically significant increase of lower intermolar (0.66-0.97 mm) and intercanine width (0.9 mm). Since no studies in the literature have analyzed the differences in permanent vs primary molars as anchoring teeth for RME, the decision to band the permanent deciduous molars did not follow a clinical protocol, but an individual decision was made for each patient based on clinician experience.