Imaging of root canal preparation

MicroCT was developed as a tool for assessing the quality of root canal preparation procedures in endodontics. Now debris can be measured in all areas of the canal with an automated calculation of the canal’s isthmus width. Investigations highlighted the biological variation present in the mandibular molar, with debris accumulating in isthmi, lateral canals and protrusions. Canals having an average isthmus width of 120-270μm resulted in 3.5x increase of debris compared to 271-630μm. Enlarging canals with a series of rotary files was shown to statistically significantly decrease debridement compared to a single reciprocating file. Regardless of irrigant or file motion, debris always remained in the canals which may become a source of reinfection, leading to treatment failure. Ultrasonic cleaning was investigated as a potential agent of a more thorough cleaning. A novel hydrogel with similar viscoelastic properties to some biofilms was created, and removal of this from canals was characterised by an initial rapid and unstable removal, followed by slower, constant viscous removal (isthmus) or the detaching of fragments of hydrogel (lateral canal). Ultrasonic cavitation effects were subsequently demonstrated to play a major role in removing biofilm in this model, although the creation of stable bubbles inhibited hydrogel removal