In vitro assessment of normal and pathological dental structures by nuclear magnetic resonance micro-imaging at high field

Aims: Aim of this work is to analyze the various field of application of Magnetic Resonance Imaging in endodontics and highlight its current advantages and limitations due to understand its future application in research and clinical practice. The effectiveness in revealing the presence or absence of a pathological condition affecting enamel, dentin, endodontic space and the quality of the apical seal of an endodontic sealing technique was investigated. Materials and methods: Three extracted monoradicular teeth were analyzed using a Bruker Avance-400 high-resolution spectrometer operating at 9.4 T with a microimaging probe (10 mm internal diameter), equipped with a gradient unit characterized by a maximum gradient strength of 1200 mT/m and a rise time of 100 μs. XWINNMR® and ParaVision® 3.0 software were employed for data acquisition and analysis. Images of teeth were weighted in T2 at different TE to measure T2 relaxation times and in Apparent Diffusion Coefficient (ADC) in different regions of interest (ROI). Results: T2 and ADC values were obtained at different ROI. Clear images of carious lesions, periodontal tissues, pulpar remnants and endodontic materials such as guttapercha cones were acquired. Presence of microcracks and a calcification of the pulp were also clearly differentiated. Conclusions: Micro MRI is a non-invasive, non-destructive tool for the assessment of pathological conditions affecting dental hard and soft tissues, and it may help in finding endodontic procedural mistreatments such as incomplete detersion or inadeguate tridimensional filling in vitro.