Micro-computed tomography: a new tool for experimental endodontology

Aim Micro-computed tomography (MCT) using cone-beam geometry is a method of producing true 3D images of the structure of small samples. A prototype MC T unit was adapted for imaging teeth to examine whether it could be used to quantify the instrumentation of root canals. Methodology Ten mandibular first molar teeth that had intact crowns and ful ly formed roots were scanned using MCT at a resolution of 0.081 mm and 3D-r endered images created; root canals were segmented from this. Reproducibili ty of MCT was verified for root canal shape and size. Access cavities were prepared into the pulp space and root canals enlarged to a continuously tap ering preparation using a crowndown technique. Each tooth was scanned again to allow comparison of pre- and post-instrumentation images. The roots wer e then sectioned at five predetermined horizontal levels for video-digitize d measurement of dimensions of roots and root canals. The video images had a resolution of 0.025 mm. Video-digitized images of the physical cut surfac es were compared with equivalent MCT reconstructed images. The total area o f the root canals (internal) and root (external) at each level were calcula ted from both MCT reconstructions and video-digitized images, and compared. Results There was a highly significant correlation between MCT and video im ages for both external and internal areas (r = 0.94). Rendered 3D images we re constructed to show the root canal systems of teeth. The total volumes o f the apical 7.5 mm of root canals were calculated from rendered images of nine teeth before and after instrumentation. The mean amount of dentine rem oved by instrumentation was 3.725 mm(3), which was 28% of the original cana l volume. Conclusions Micro-computed tomography was shown to be accurate for experime ntal endodontology.