Shaping ability of Quantec Series 2000 rotary nickel-titanium instruments in simulated root canals: Part 2

The aim of this laboratory based study was to determine the shaping ability of Quantec Series 2000 nickel-titanium rotary instruments in simulated root canals. A total of 40 canals with four different shapes in terms of angle and position of curve were prepared with Quantec Series 2000 instruments using the technique recommended by the manufacturer. Part 2 of this report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall post-operative shape. Pre- and post-operative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and post-operative views were superimposed to highlight the amount and position of material removed during preparation. Twenty-one zips and elbows were created during preparation with a significant difference (P < 0.005) between canal shapes in terms of the incidence of aberrations. Four perforations were created, with significant differences (P < 0.005) between the canal shapes; three ledges were also created but no danger zones. Highly significant differences (P < 0.001) were apparent between the canal shapes in total canal width at specific points along the canal length and in the amount of resin removed from the inner and outer aspects of the curve. Canal transportation at the end-point of preparation was most frequently directed towards the outer aspect of the curve, and without exception in canals with 40 degrees curves. At the beginning of the curve, transportation became more evenly balanced between the inner and outer aspect of the curve, although predominated towards the outer. Transportation was generally directed towards the outer at the orifice, especially in canals with 40 degrees curves. Mean absolute transportation at the various measurement points was less than 0.11 mm; significant differences occurred between canal shapes at the end-point of preparation (P < 0.0001), at the zips (P < 0.005), at the apex (P < 0.0001) and beginning of the curve (P < 0.05) and at the orifice (P < 0.0001). Under the conditions of this study, Quantec Series 2000 rotary nickel-titanium instruments created a relatively large number of aberrations including four perforations. The aberrations were created by the larger instruments implying that these should be used with caution at the full working distance. Scanning electron micrographs of these instruments revealed sharp instrument tips which appeared likely to predispose to transportation and the creation of defects along the outer aspect of severely curved canals.