Human dental age estimation by cone beam computed tomography - an in vitro study

The formation of secondary dentine leads to an age-related decrease of the pulp cavity volume. Hence, the volume of the pulp cavity relative to the volume of its tooth could be useful for dental age estimation based on three-dimensional cone-beam computed tomography (CBCT) x-ray images. A sample of 69 single-rooted teeth from 26 patients aged 19-89 years was collected for this pilot study. The teeth had no caries or signs of restaurative dental treatment and showed unimpaired root apices. All teeth were scanned by a CBCT (Accuitomo, J. Morita, Kyoto, Japan) using an clearly defined experimental set up ensuring a uniform exposure setting, determined by pretrials.Using threshold segmentation, three methods for segmentation and volume measurement of enamel, dentine and pulp cavity were tested. Tooth and pulp volumes and volume ratios were calculated for the whole tooth, the root region and at four levels. The relationship between the volume ratios and age was determined by Pearson's correlation coefficient (r), the accuracy of age estimation by the determination coefficient R². The Wilcoxon sign rank test was employed to measure the intraobserver error of manual segmentation. From the three segmentation methods, the manual non-reconstructable method showed the highest coefficient of determination (R² = 0,663). There were no statistically significant intraobserver differences. From the specific volume ratios, the highest correlation was observed for the coronal third of the root (R² = 0,621). The results provide support for the use of tooth-pulp volume measurements from clinically acquired CBCT images for age estimation. Keywords: dental age estimation, pulp-tooth-volume ratio, secondary dentine/formation, forensic dentistry, cone-beam computed tomography, VoXim