LAUSR

OBJECTIVE The aim of this study was to determine among young orthodontic patients the relation between the spheno-occipital synchondrosis (SOS) fusion and the cervical vertebral maturation (CVM) and to look for an eventual impact of gender, skeletal class and vertical pattern on their association. MATERIAL AND METHODS CBCT scans and lateral cephalometric radiographs of 117 patients, aged between 8 and 18 years, were selected. SOS fusion was assessed on a mid-sagittal cut of the CBCT scans. CVM was evaluated on the lateral cephalograms as well as ANB and GoGn-SN angles. Spearman correlation test was used to assess the relationship between SOS and CVM. Fisher's exact test was performed at every CVM stage to analyse the association between SOS and other variables (gender, skeletal class, and vertical pattern). Cohen's kappa analysis was used for reliability. RESULTS A strong correlation was found between SOS maturation and CVM (r=0.852, P<001). Fisher's exact test indicated significant association only between gender and SOS in CVM stage 2 group, and between vertical pattern and SOS in CVM stage 4. Cohen's kappa analysis showed moderate inter and intra-rater reliability for CVM index (k=0.50 and 0.53 respectively, P<.001), strong inter-rater reliability (k=0.80, P<.001) and almost perfect intra-rater reliability (k=0.85, P<.001) for SOS index. CONCLUSIONS SOS fusion correlates well with CVM and might be a reliable tool for skeletal maturation assessment. Girls seem to have an earlier fusion of SOS in relation to their respective CVM compared to boys, and the vertical pattern could influence the association between SOS and CVM stages.