[Accuracy of 3D reconstruction of pulp cavity in mandibular premolars based on cone-beam CT]

To analyze the accuracy of 3D reconstruction of pulp cavity in mandibular premolars based on cone-beam CT (CBCT).

Thirty-two extracted single-rooted mandibular premolars were randomly collected and scanned by micro-CT and CBCT. After image segmentation and 3D reconstruction, the surface model and volume model of the pulp cavity were rendered. By using Amira 5.0 software, each pairs of pulp cavity surface models were registered. The surface models reconstructed from micro-CT scanning were set as the references and the surface models reconstructed from CBCT were tested. The morphological differences between each pairs of surface models were calculated by Amira 5.0 software and represented by color-coded maps. The total 3D morphological difference value of each sample was recorded and the volume reconstruction differences between the two image acquisition techniques were analyzed. Statistical analysis was performed with SPSS 13.0 software package.

The mean value of 3D morphological differences of 32 teeth was 0.27 mm. Distribution of the greatest morphological differences were mainly located in the apical portion of the pulp cavity and some small anatomical variation. The volume of the reconstructed models by micro-CT and CBCT were (34.89±4.36) mm³ and (27.32±4.83) mm³ respectively, and the difference was significant (P＜0.05).

When CBCT scanning is used to reconstruct pulp cavity of mandibular premolars, there is certain degree of information loss, which mainly distributes in the apical portion and small anatomical variation sites. Dentists should consider these characteristics during clinical application of CBCT.