Introduction: Although rapid maxillary expansion is widely used for patients with transverse discrepancy with good predictability during growth, adverse reactions have been observed, such as excessive inclination and orientation of the teeth used for anchoring in this type of appliances, as well as possible gingival recessions. Objective: Comparing maxillary expansion at the skeletal and dental levels through the use of a TAD RPE and a Bonded RPE. Method: Two monozygotic twins, 13 years and 3 months old. Patient A presents a maxilla with a transverse skeletal discrepancy and a cross bite on the left side. Patient B presents a maxilla with a transverse skeletal discrepancy and a cross bite on the right side. However, both lateral crossbites have the same malocclusion (mirror image). The TAD RPE was used in patient A, while the Bonded RPE was installed in patient B. Conclusion: The use of a TAD RPE can prevent corono-vestibular inclination due to non-use of teeth for anchoring.
(Rev Esp Ortod. 2018;48(3):103-111)