Effects of four Ni-Ti preparation techniques on root canal geometry assessed by micro computed tomography

Aim The aim of this study was to compare the effects of four preparation te chniques on canal volume and surface area using three-dimensionally reconst ructed root canals in extracted human maxillary molars. In addition, mu CT data was used to describe morphometric parameters related to the four prepa ration techniques. Methodology A micro computed tomography scanner was used to analyse root ca nals in extracted maxillary molars. Specimens were scanned before and after canals were prepared using Ni-Ti - K-Files, Light speed instruments, Profi le .04 and GT rotary instruments. Differences in dentine volume removed, ca nal straightening, the proportion of unchanged area and canal transportatio n were calculated using specially developed software. Results Instrumentation of canals increased volume and surface area, Prepar ed canals were significantly more rounded, had greater diameters and were s traighter than unprepared canals. However, all instrumentation techniques l eft 35% or more of the canals' surface area unchanged. Whilst there were si gnificant differences between the three canal types investigated, very few differences were found with respect to instrument types. Conclusions Within the limitations of the mu CT system, there were few diff erences between the four canal instrumentation techniques used. By contrast , a strong impact of Variations of canal anatomy was demonstrated, Further studies with 3D-techniques are required to fully understand the biomechanic al aspects of root canal preparation.