Maxillary Response Induced by Rapid Palatal Expansion Vs. Clear Aligners: A Short-Term Retrospective Evaluation of the Dento-Alveolar Effects in Mixed Dentition

Background: to analyze the dento-alveolar effects induced by two treatment appliances (i.e., RME and Clear Aligners) in growing subjects presenting with early mixed dentition and mild maxillary deficiency. Methods: digital casts of 32 children treated with RME (RG: 17 subjects) or with Clear aligners (CAG: 15 subjects) were collected. Linear and angular values were measured in both groups on the upper arch for both pre- (T1) and post-treatment (T2) models. An unpaired t-test was used to test significant differences between groups (p < 0.05). Results: the comparison of T2-T1 changes for linear measurements between groups showed a greater increase in the inter-canine width (+1.5 mm ± 0.5 mm) and in the first inter-deciduous molar width (+1.4 ± 0.4 mm), also at the trans-palatal level in the CAG group. Conversely, in the posterior region of the upper arch, a greater increase in the first inter-molar distal width was found in the RG group (+1.2 ± 0.4 mm) when compared with the CAG group. A significant increase in the crown angulation in the CAG group was found for all the teeth except for the first molars. Conclusions: the rapid palatal expander widened the palate, tipping the first upper molars buccally to a greater extent, whereas the Clear aligners caused a greater increase in the canine width.