Retrospective CBCT analysis of airway volume changes after bone-borne vs tooth-borne rapid maxillary expansion
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Objectives: To compare changes in upper airway volume after maxillary expansion with bone and tooth-borne appliances in adolescents and to evaluate the dentoskeletal effects of each expansion modality. Materials and Methods: This retrospective study included 36 adolescents who had bilateral maxillary crossbite and received bone-borne maxillary expansion (average age: 14.7 years) or tooth-borne maxillary expansion (average age: 14.4 years). Subjects had two cone beam computed tomography images acquired, one before expansion (T1) and a second after a 3-month retention period (T2). Images were oriented, and three-dimensional airway volume and dentoskeletal expansion were measured. Analysis of variance was used to test for differences between the two expansion methods for pretreatment, posttreatment, and prepost changes. Paired t-tests were used to test for significance of prepost changes within each method. Results: Both groups showed significant increase only in nasal cavity and nasopharynx volume (P,.05), but not oropharynx and maxillary sinus volumes. Intermolar and maxillary width increased significantly in both groups (P ,.05); however, the buccal inclination of maxillary molars increased significantly only in the tooth-borne group (P ,.05). There was no significant difference between tooth- and bone-borne expansion groups, except for the significantly larger increase in buccal inclination of the maxillary right first molar after tooth-borne expansion. Conclusions: In adolescents, both tooth- and bone-borne RME resulted in an increase in nasal cavity and nasopharynx volume, as well as expansion in maxillary intermolar and skeletal widths. However, only tooth-borne expanders caused significant buccal tipping of maxillary molars.