Root canal preparation with Endo-Eze AET: changes in root canal shape assessed by micro-computed tomography

To evaluate the relative performance of Endo-Eze Anatomic Endodontic Technology (AET) stainless steel instruments when shaping maxillary molar root canals in vitro. Methodology Extracted human maxillary molars were scanned, before and after root canal shaping with Endo-Eze AET, employing micro-computed tomography (muCT) at an isotropic resolution of 34 microm. Three-dimensional root canal models were reconstructed and evaluated for volume, surface area, 'thickness' (diameter), canal transportation and prepared surface. Preparation errors such as apical zips, perforations and fractured instruments were visually determined from those models. Means were contrasted using anova and Scheffé post-hoc tests.

Volume and surface area increased significantly and similarly in mesiobuccal (mb), distobuccal (db) and palatal (p) canals and gross preparation errors (n = 17) were found. Mean root canal diameters, 5 mm coronal to the apex, increased from 0.31 to 0.52, 0.35 to 0.50 and 0.50 to 0.70 mm for mb, db and p canals, respectively. Mean canal transportation ranged from 0.15 to 0.29, 0.15 to 0.27 and 0.21 to 0.33 mm for apical, middle and coronal root canal levels, respectively, with highest values found for mb canals (P < 0.003). Root canals were significantly straightened during preparation (P < 0.002).

In summary, Endo-Eze AET instruments shaped root canals in maxillary molars with substantial canal transportation, particularly in mesiobuccal root canals. Preparation with this instrument removed high volumes of dentine, even though apical preparation was size 30. Based on the current results, Endo-Eze AET cannot be recommended for the preparation of teeth with curved root canals.