Post-retention effects of rapid maxillary expansion on nasal cavity and on periodontal structures.

The aim of this study was to apply low-dose CT scans to evaluate the treatment and post-retention effects of RME on nasal cavity and periodontal effects. Materials and methods. CT scans of 17 subjects (7 males 10 females, mean age 11.2 years) were taken before RME (T0), at the end of the expansion phase (T1), and after a retention period of 6 months (T2). Measurements were performed on axial scans and on 3 different coronal scans. Statistical analysis was performed with ANOVA for repeated measures with post-hoc tests. Results. Transverse dimensions of nasal cavity showed statistically significant T0-T1 increments at all the 3 coronal scans. All T0-T1 increments at the nasal levels showed a decrease in magnitude from the anterior to the posterior measurements. In the evaluation of T0-T1 changes, periodontal measurements were significant on the buccal aspect of banded teeth with a reduction in alveolar bone thickness. In the evaluation of T0-T2 changes, the lingual bone plate thickness resulted significantly increased. Conclusions. RME therapy induces a significant increase in the transverse dimension of the nasal cavity without permanent injuries to the periodontal bony support discernible at CT imaging. After six months the expansion of the nasal cavity results stable.