Age Estimation Based on Cone-Beam Computed Tomography of the Spheno-Occipital Synchondrosis and Demirjian Method in an Iranian Population

Spheno-occipital synchondrosis is a growth center that is involved in craniofacial development. Since osteogenesis of this synchondrosis occurs relatively later than other synchondroses, it has been taken into account for age estimation in forensics. This study aimed to evaluate spheno-occipital synchondrosis using Cone-Beam Computed Tomography (CBCT) in an Iranian population.  In this cross-sectional study, 148 CBCT images (76 women and 72 men) of patients aged 7-25 years, with a mean age of 19.92±6.3 years, were assessed by two radiologists to analyze the spheno-occipital synchondrosis fusion degree using a four-stage system. In addition, the third molar development degree (Demirjian index) was assessed in panoramic and cross-sectional views of CBCT images. The correlation between spheno-occipital synchondrosis fusion degree and age was obtained. Multiple regression analysis was used for age estimation using spheno-occipital synchondrosis fusion degree and third molar development degree (Demirjian index). Intra-observer and inter-observer coefficients of agreements were also measured. IBM SPSS Statistics 20.0 was used.  There was a positive correlation between spheno-occipital synchondrosis fusion degree and age (r=0.75, p<0.001). The multiple regression model provides a more robust model than when each age marker is utilized individually. The kappa coefficient was 0.53 for inter-observer agreement and 0.77-0.92 for intra-observer agreement.  Assessing the four-stage spheno-occipital synchondrosis fusion degree was not a robust method; however, combined with the third molar development (Demirjian index), it could be considered as an appropriate marker for age estimation in 7-25-year-old Iranian population.