Comparison of measurement of the apical anatomy of maxillary central incisors using cone-beam computed tomography and conventional intraoral radiographs

The aim of this study was to investigate the dimension of the apical foramen in maxillary incisors in relation to age as observed in conventional intra-oral periapical radiographs and Cone-Beam CT (CBCT). We hypothesized a discrepancy in apical foramen size between 2D radiographs and 3D CBCT, and that the foramen narrows with age. Seventy patients with 87 anterior maxillary teeth were included. The shape, size and the area of the apical foramen were measured corresponding to the narrowest part of the canal system (the apical constrictor/minor foramen) on intraoral conventional X-rays and CBCT scans taken in close succession. A comparison between the two imaging methods was performed and related to the age of the patient, with statistical analyses including t-test, regression, and Bland-Altman plots. In addition, the area of the foramen was measured, and a shape index was calculated from the CBCT scans. The area of the apical foramen measured in 3D using CBCT, decreased at a rate of -0.019 mm2 per month. The diameter of the foramen decreased at a rate of -0.014 mm per month (2D, mesiodistal dimension), -0.013 mm per month (3D, mesiodistal) and − 0.016 mm pr month (3D, faciolingual). The correlation between the mesiodistal diameter in 2D and 3D was fair with R = 0.60, and the correlation between mesiodistal and faciolingual diameter in 3D was high (R = 0.77). The mean shape index was found to be 0.992 ± 0.244. The present study found that area and diameter (mesiodistal and faciolingual directions) of the foramen, measured to be equivalent to the apical constrictor, decreased with age. The most common shape of the apical constriction was round. There was a significant difference between the diameter of the foramen measured on conventional periapical radiographs compared to the CBCT scans.