Maxillary dentoskeletal outcomes of the expander with differential opening and the fan-type expander: a randomized controlled trial.

OBJECTIVES The aim of this study was to compare the maxillary dentoskeletal outcomes of the expander with differential opening (EDO) and the fan-type expander (FE). MATERIAL AND METHODS Forty-eight patients with maxillary arch constriction in the mixed dentition were randomly allocated into EDO and FE groups. Cone-beam computed tomography scans were acquired before and after expansion. Linear and angular three-dimensional changes were assessed after cranial base superimposition using the ITK-SNAP and the 3D Slicer software. T or Mann-Whitney U tests were used for intergroup comparisons (P<0.05). RESULTS The EDO group comprised 24 patients treated with the EDO (13 female, 11 male; 7.6 years). The FE group comprised 24 patients treated with the FE (14 female, 10 male; 7.8 years). Skeletal lateral displacements were greater in the EDO group with greater expansion in the orbital, nasal cavity, zygomatic bone, and palate regions (mean intergroup differences of 0.4, 0.8, 0.9, and 1.1 mm, respectively). Intercanine expansion and canine buccal inclination were greater in the FE group, while intermolar distance changes and molar buccal inclination were greater in the EDO group. Similar changes were observed for vertical and anteroposterior displacements and palatal plane rotation. CONCLUSIONS The EDO produced greater transverse skeletal expansion compared to the FE, with similar vertical and anteroposterior effects. Dental changes were greater in the molar region for patients treated with the EDO and in the canine region for patients treated with the FE. CLINICAL RELEVANCE The EDO and the FE are capable of producing skeletal changes in the mixed dentition. The decision between both expanders will depend on the amount of expansion required in the molar region and in the nasomaxillary complex. TRIAL REGISTRATION The trial was registered at ClinicalTrials.gov , under the identifier NCT03705871.