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 withtooth-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 age14.27 ± 1.36 years) or bone-borne (BB group = 20; mean age of 14.62 ± 1.45 years) maxillary expander. Cone-beamcomputed 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 technologyinvolving 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 thepercentage 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 cm3 and 0.77 cm3) (p < 0.0001).This increment were significant between the two groups (p < 0.05) while no differences were found in thepercentage of matching of T1/T2 orbital 3D models (p > 0.05). The areas of greater changes were detected in theproximity of the frontozygomatic and frontomaxillary sutures.Conclusion: TB-RME and BB-RME would not seem to c onsiderably affect the anatomy or the volume of the orbitalcavity in adolescents.