Use Of Micro Computed Tomography To Assess Root Canal Geometry O. A. Peters*, K. Schönenberger, T.N. Göhring, C. Peters, A. Laib (Department Of Preventive Dentistry, Periodontology And Cariology, Division Of Endodontics, University Of Zurich, Zurich, Switzerland) Objectives. Detailed knowledge of the micro-anatomy of root canal systems is essential for successful endodontics. The current study employed high resolution computed tomography (µCT) to quantitatively assess changes in the canals’ geometry after preparation using 4 different NiTi preparation systems.   Material and Methods. A commercially available µCT scanner (Scanco, Bassersdorf, Switzerland) was used to analyse 40 extracted maxillary molars. Teeth were scanned before & after 30 matched canals each were prepared using NiTi K-Files, Lightspeed, ProFile .04 & GT Files. A precise repositioning device allowed repeated scanning of specimens in the same orientation. Dentine volumes and surface areas for each canal before & after preparation were calculated using specially developed software. Differences between means were analysed ANOVA applied to a repeated measures model.   Results. Mean canal volumes (± SD) & surface areas were 2.30 mm³ (± 1.51) & 18.76 mm² (± 7.72) before canal preparation and 4.39 mm³ (± 1.60 ) & 24.45 mm² (± 6.63) after preparation. Changes in canal volumes and surface areas differed significantly (p<0.001) with respect to canal type. No significant differences were found with respect to instrument type.   Conclusion. Under the conditions of this study, preparation with hand or rotary NiTi instruments resulted in statistically similar changes in canal volumes and surface areas. Further analyses are required to reveal possible subtle changes in the canals’ paths during preparation. This may be done utilising the novel non-destructive approach presented.