Retrospective CBCT analysis of airway volume changes after bone-borne vs tooth-borne rapid maxillary expansion

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 (T-1) and a second after a 3-month retention period (T-2). 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.