Abstract: Aim This was to evaluate changes in spheno-occipital synchondrosis one year after rapid maxillary expansion (RME), in order to assess the influence that any change might have on sagittal and vertical skeletal cephalometric variables.
Materials and methods Patients were selected consecutively and grouped into: Group 1 comprised 30 Caucasian patients (13 m; 17 f) undergoing RME therapy; after active expansion therapy, the Haas expander was worn as passive retainer for an average of 7 months. Group 2 as control included 14 untreated subjects (6 m, 8 f), matched by age, sex and vertebral skeletal maturity (CVM method, stages 1-3). Six cephalometric variables concerning spheno-occipital synchondrosis were studied: N-S-Ba°; SOS-Ba; SOS-S; S-Ba; Ba-N; S-N; nine skeletal variables for sagittal and vertical evaluation were also checked. T-test was used for comparing the 2 groups data.
Results A statistically-significant opening of the spheno-occipital synchondrosis and increase of the posterior cranial base length (Ba-SOS) were found between group 1 and 2. After 1 year, these modifications in spheno-occipital syncondrosis produced no change in the anteroposterior or vertical skeletal parameters examined.
Conclusion After RME there were statistically-significant effects on spheno-occipital synchondrosis length and cranial base angle; however, these changes in the mid-term did not affect the vertical or sagittal parameters of the skeletal maxillomandibular complex.