Canal wall thickness after preparation with NiTi rotary files

Root canal preparation is the most important phase of endodontic procedure and it consists of adequate canal space cleaning and shaping. In recent years, rotary instruments and techniques have gained importance because of the great efficacy, speed, and safety of the preparation procedure.

The aim of this research was to investigate measurement of maximal and minimal residual dentine thickness (RDT) and canal diameter after the canal preparation with different NiTi rotary files.

The research has been conducted on extracted human teeth in vitro conditions. The teeth have been divided in seven groups (20 teeth per group) depending on the kind of instruments used for root canal preparation: ProTaper, GT, ProFile, K-3, FlexMaster, hand ProTaper, and hand GT. The canals have been shaped in a crown-down manner and irrigated with 5.25% sodium hypochlorite. The roots of the teeth have been cut 1 and 3 mm from the apex. Apical preparation quality has been assessed under the polarized light microscope.

The maximal residual dentine thickness at distance 1 mm from apex, ranged from 1.16 to 1.45 mm, and at distance 3 mm from apex, from 1.44 to 1.84 mm. The minimal dentine thickness at distance 1 mm from apex ranged from 0.52 to 0.73 mm, and at distance 3 mm from apex, from 0.66 to 0.83 mm. The canal diameters after preparation at distance 1 mm from apex ranged from 0.42 to 0.49 mm, and at distance 3 mm from apex, from 0.53 to 0.63 mm.

There was no significant difference neither in maximal and minimal RDT, nor in canal diameters shaped with different NiTi instruments tested. All tested NiTi files have accomplished good quality preparation of apical root canal parts.