Human tooth and root canal morphology reconstruction using magnetic resonance imaging

Abstract

Background and aims: Visualization of the internal and external root canal morphology is very important for a successful endodontic treatment; however, it seems to be difficult considering the small size of the tooth and the complexity of the root canal system. Film-based or digital conventional radiographic techniques as well as cone beam computed tomography provide limited information on the dental pulp anatomy or have harmful effects. A new non-invasive diagnosis tool is magnetic resonance imaging, due to its ability of imaging both hard and soft tissues. The aim of this study was to demonstrate magnetic resonance imaging to be a useful tool for imaging the anatomic conditions of the external and internal root canal morphology for endodontic purposes.

Methods: The endodontic system of one freshly extracted wisdom tooth, chosen for its well-known anatomical variations, was mechanically shaped using a hybrid technique. After its preparation, the tooth was immersed into a recipient with saline solution and magnetic resonance imaged immediately. A Bruker Biospec magnetic resonance imaging scanner operated at 7.04 Tesla and based on Avance III radio frequency technology was used. InVesalius software was employed for the 3D reconstruction of the tooth scanned volume.

Results: The current ex-vivo experiment shows the accurate 3D volume rendered reconstruction of the internal and external morphology of a human extracted and endodontically treated tooth using a dataset of images acquired by magnetic resonance imaging. The external lingual and vestibular views of the tooth as well as the occlusal view of the pulp chamber, the access cavity, the distal canal opening on the pulp chamber floor, the coronal third of the root canals, the degree of root separation and the apical fusion of the two mesial roots, details of the apical region, root canal curvatures, furcal region and interradicular root grooves could be clearly bordered.

Conclusions: Magnetic resonance imaging offers 3D image datasets with more information than the conventional radiographic techniques. Due to its ability of imaging both hard and soft dental tissues, magnetic resonance imaging can be successfully used as a 3D diagnostic imaging technique in dentistry. When choosing the imaging method, dental clinicians should weight the benefit-risk ratio, taking into account the costs associated to magnetic resonance imaging and the harmful effects of ionizing radiations when cone beam computed tomography or conventional x-ray are used.

Keywords: magnetic resonance imaging; radiographic image enhancement; radiography; root canal; tooth morphology.

Figure 1

3D volume reconstruction of the internal and the external morphology of an endodontically treated third molar. A. Distal-vestibular view of the distal root and root canal shaped at a 6% taper. An edifying image of the prepared root canal provided by MRI. A clear view upon the irregular shape of the prepared distal root canal, meaning that a part of the complex anatomy of the distal root canal was left untouched, i.e., not cleaned by the mechanical shaping files. B. Vestibular view of the external morphology of mesio vestibular and distal roots and the correspondingly shaped root canals. Root canal curvatures, the furcal region, the interradicular root grooves can be clearly seen. C. Proximal (mesial) view. Note the degree of root separation and the apical fusion of the two mesial roots. D. Detail of the apical part of the three roots and root canals. The root canal openings (portal of exits), the apical finishing of the root canal treatment can be viewed with great accuracy.

Figure 2

3D volume rendered filled surface reconstruction. A. External Lingual view; B. External Vestibular view; C. Occlusal view of the pulp chamber; D. Access Cavity; E. View of the distal canal opening, on the pulp chamber floor; F. Distal Root canal opening (close-up); G. View inside the coronal third of the root canal.