Transverse dentoalveolar response of mandibular arch after rapid maxillary expansion (RME) with tooth-borne and bone-borne appliances.

Objectives: To assess and compare spontaneous expansion of mandibular posterior teeth between tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME).
Materials and Methods: This study included 36 adolescents with bilateral maxillary crossbite receiving tooth-borne (average age: 14.4 ± 1.3 years) or bone-borne (average age: 14.7 ± 1.4 years) maxillary expansion. Cone beam computed tomography was acquired before expansion (T1) and after 6 months' retention (T2). Specific linear and angular measurements were performed in the coronal view to assess buccal inclinations and widths of mandibular posterior units. All data were statistically analyzed.
Results: In both groups there was a significant increase in buccal-lingual inclination of mandibular posterior teeth ranging from 1.67° to 2.30° in the TB group and from 1.46° to 2.11° in BB group. Mandibular posterior widths showed an increase ranging from 0.80 mm to 1.33 mm in TB group and from 0.64 mm to 0.96 mm in the BB group. No differences between groups were found for linear or angular measurements.
Conclusions: A clinically significant gain of space in the mandibular arch should not be expected after RME.
(© 2020 by The EH Angle Education and Research Foundation, Inc.)