Forensic Individual Identification Based on the New Coding Method of Oral Pano-ramic Tomography / 法医学杂志

Objective To discuss a new coding method for individual identification based on oral panoramic tomography, analyze the diversity of different coding modules in nonhomologous images and the consistency and the matching rate of the coding indexes of different coding modules in homologous images, and evaluate the application value of the different modules and the new coding method in individual identification. Methods The oral panoramic tomography images of 1 000 patients with permanent teeth were collected retrospectively. Each patient had two images taken at different times （called the Early database and the Late database according to the chronological order）. Each image was coded according to the designed coding method. A computer program was designed to compare the diversity of different modules, and calculate the diversity and consistency of different coding modules as well as the matching rate of the coding indexes. Results The diversity of the 4 modules that reflected teeth characteristics was much higher than that of other modules in the same database. The highest diversity was noticed in the module of right mandibular teeth in samples of both databases. The coding consistencies of the 4 modules were all above 50%. Besides, 90.2% of the matching rates of indexes of homologous images were over 80%. Conclusion The 4 modules have higher application value in individual identification, especially the right mandibular teeth. The coding method has a certain value in forensic individual identification.

Age Estimation in Han Adults by Thin-Layer CT Scan of Cranial Sutures / 法医学杂志

Objective To explore the value of degree of cranial suture closure in forensic adult age estimation by thin-layer CT scan and establish an adult age estimation model of the Han nationality. Methods Thin-layer CT scan samples of the heads of 220 healthy Sichuan Han adults （110 males, 110 females） aged 20 to 70 were collected, of which 20 samples （10 males, 10 females） were randomly selected as test samples. The sagittal suture, coronal suture （both left and right） and lambdoid suture （both left and right） were respectively and equally divided into 2 segments, and every segment was equally divided into 10 layers and the corresponding multiplanar reformation （MPR） images were selected. The closure of cranial sutures on MPR images was classified into the grades 1-7. The correlations between cranial sutures and age were analyzed to build regression equation for age estimation. Results The degree of closure of sagittal suture, coronal suture （both left and right） and lambdoid suture （both left and right） was positively correlated with age. The coefficient of determination （R2） of regression equation was 0.419 in males, 0.589 in females, and 0.522 in all samples. The results of the verification test showed that the mean absolute error （MAE） was 6.39 years in males, 6.16 years in females, and 6.29 years in all samples. Conclusion There was a higher accuracy in adult age estimation by thin-layer CT scan of cranial sutures. The age of Han nationality adults can be estimated by the degree of cranial sutures closure.