Computed tomography evaluation of rapid maxillary expansion: a case report

Daniela Gamba GARIB, José Fernando Castanha HENRIQUES, Guilherme JANSON, Régis Antonio COELHO

This paper presents a computed tomography (CT) evaluation of rapid maxillary expansion dentoskeletal and periodontal effects, in a 11.6 year-old girl presenting Class I malocclusion with posterior unilateral crossbite. The toothborne expander with Hyrax screw was activated 7-mm. The patient was submitted to helicoidal CT scan before expansion and after the three-month retention period when the expander was removed. Axial sections with 1-mm thickness were performed parallel to the palatal plane, comprising dentoalveolar and basal areas of maxilla, up to the inferior third of the nasal cavity. Multiplanar reconstruction was employed for achievement of the following measurements by means of the computerized method: maxillary transverse dimensions, posterior teeth inclination, buccal and lingual bone plates thickness, and buccal alveolar crest level. The rapid maxillary expansion yielded a significant transverse increase in all areas measured, of decreasing magnitude from dental arch to basal bone. Posterior teeth were moved in buccal direction, which was associated to both inclination and translation. This orthodontic effect produced a buccal bone plate thickness redution and a lingual bone plate thickness increase. After expansion, bone dehiscences were observed on supporting teeth buccal aspect.

Keywords: Rapid maxillary expansion. Tomography. X-ray computed.

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