Correction of maxillary transverse deficiency in growing patients with permanent dentitions

This article describes the correction of maxillary transverse deficiency using Memoria Leaf Spring Activated Expander following the standardized protocol proposed by Lanteri and colleagues. Digital models made before and after expansion were used to evaluate the effectiveness of the expander.Since the leaf springs come fully compressed from the lab, the preactivation should theoretically result in roughly 4mm of expansion as the springs decompress over time. The force expressed by the leaf springs diminishes after 2mm of decompression, however, so that in our experience, a clinician can assume that only half of this preactivation will be expressed. If 1mm of expansion can be obtained for every 10 activations of the expansion screw, as confirmed by the two cases shown here, another 2mm should be added to the total to account for preactivation of the appliance.