External and internal macromorphology in 3D‐reconstructed maxillary molars using computerized X‐ray microtomography

TLDR

Fractal dimension analysis revealed a strong correlation between root canal shape and root morphology, suggesting that 3D volumes could serve as a platform for preclinical endodontic training. The study aimed to qualitatively analyze the relationship between external and internal macromorphology of the root complex and to use fractal dimension analysis to assess the correlation between the outer root surface and root canal shape. Using X‑ray micro‑tomography, five maxillary molars were scanned to produce 100–240 slices per tooth, assembled into 3D volumes with noise filtering, segmented into enamel, dentine, and pulp, and rendered with transparent hard tissues and opaque pulp for visualization. The analysis showed strong agreement between the number, position, and cross‑section of root canals and the corresponding root complex macrostructures, with fractal dimension analysis confirming a high correlation between root canal shape and root shape.

Abstract

The aim of this study was to perform a qualitative analysis of the relationship between the external and internal macromorphology of the root complex and to use fractal dimension analysis to determine the correlation between the shape of the outer surface of the root and the shape of the root canal.On the basis of X-ray computed transaxial microtomography, a qualitative and quantitative analysis of the external and internal macromorphology of the root complex in permanent maxillary molars was performed using well-defined macromorphological variables and fractal dimension analysis. Five maxillary molars were placed between a microfocus X-ray tube with a focal spot size of 0.07 mm, a Thomson-SCF image intensifier, and a CCD camera compromising a detector for the tomograph. Between 100 and 240 tomographic 2D slices were made of each tooth. Assembling slices for 3D volume was carried out with subsequent median noise filtering. Segmentation into enamel, dentine and pulp space was achieved through thresholding followed by morphological filtering. Surface representations were then constructed. A useful visualization of the tooth was created by making the dental hard tissues transparent and the pulp chamber and root-canal system opaque. On this basis it became possible to assess the relationship between the external and internal macromorphology of the crown and root complex.There was strong agreement between the number, position and cross-section of the root canals and the number, position and degree of manifestation of the root complex macrostructures. Data from a fractal dimension analysis also showed a high correlation between the shape of the root canals and the corresponding roots.It is suggested that these types of 3D volumes constitute a platform for preclinical training in fundamental endodontic procedures.