Spheno-Occipital Synchondrosis Fusion Degree as an Age Estimation Tool: A Cone-Beam Computed Tomography Study

Considering the late ossification potential of spheno-occipital synchondrosis (SOS), it can be used as a tool to estimate age in adolescents. The time of SOS fusion is known to vary in different populations.

This study aimed to assess the degree of SOS fusion in Iranian individuals, using cone-beam computed tomography (CBCT) scan.

The CBCT images of 240 patients (126 females and 114 males), aged 6 - 25 years, were assessed regarding the degree of SOS fusion, based on a four-stage scoring system. Spearman’s correlation coefficient test and regression analysis were performed to assess the correlation between age and fusion stage. Mann-Whitney test was also applied to determine differences between males and females. Besides, Kruskal-Wallis test was used to assess differences in the median values.

The SOS was completely open at the mean age of 7.63 years in females and 8.85 years in males. The mean age of partially fused SOS (stage 1) was eight years in females and 10 years in males. Besides, the mean age of completely fused SOS (stage 3) was 12 years in females and 16 years in males. The results of Spearman’s correlation coefficient test showed a significant positive relationship between age and the degree of SOS fusion in males and females (rs = 0.783, P < 0.001 in females and rs = 0.911, P < 0.001 in males).

The SOS closure degree can be applied for age estimation in the Iranian population. This study presented a method which is highly accurate for age estimation.