Evaluation of the changes of orbital cavity volume and shape after tooth-borne and bone-borne rapid maxillary expansion (RME)

Objective To assess and compare volumetric and shape changes of the orbital cavity in patients treated with tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME). Study design Forty adolescents with bilateral maxillary cross-bite received tooth-borne (TB group = 20; mean age 14.27 +/- 1.36 years) or bone-borne (BB group = 20; mean age of 14.62 +/- 1.45 years) maxillary expander. Cone-beam computed tomography (CBCT) were taken before treatment (T1) and 6-month after the expander activation (T2). Volumetric and shape changes of orbital cavities were detected by referring to a specific 3D digital technology involving deviation analysis of T1/T2 CBCT-derived models of pulp chamber. Student's t tests were used to 1) compare T1 and T2 volumes of orbital cavities in TB and BB groups, 2) compare volumetric changes and the percentage of matching of 3D orbital models (T1-T2) between the two groups. Results Both TB and BB groups showed a slight increase of the orbital volume (0.64 cm(3)and 0.77 cm(3)) (p < 0.0001). This increment were significant between the two groups (p < 0.05) while no differences were found in the percentage of matching of T1/T2 orbital 3D models (p > 0.05). The areas of greater changes were detected in the proximity of the frontozygomatic and frontomaxillary sutures. Conclusion TB-RME and BB-RME would not seem to considerably affect the anatomy or the volume of the orbital cavity in adolescents.