(PR38) The Effect of Alloy Design on the Relative Performance of NiTi Rotary Files in 3D-Printed Replicas with Apical and Mid-Root Curves

Abstract: A first maxillary molar 3D printed model was used to study the effect of alloy design on the relative performance of NiTi rotary files in canals with apical and mid-root curves, represented respectively by mesio-buccal (MB) and disto-buccal (DB) canals. Following glide path to a #15 K-file, MB and DB canals were instrumented in a crown-down approach with Vortex Blue (Dentsply, n=4) or ZenFlex (Kerr, n=4) files to a 35/0.04 size. Subsequently, the replicas were instrumented with respective systems to a 40/0.04 size. Replicas were imaged by microcomputed tomography (10um voxel resolution) after glide path and instrumentations. Results for root canal transportation (1-7mm from the apex) and percent dentinal wall surface modified were obtained on a slice-by-slice basis. While there were no significant differences between file systems in percent dentin wall surface modified within canal thirds, ZenFlex showed a clear trend towards reaching peak percent values at 2mm from the apex in DB canals, compared to 4mm for Vortex Blue-instrumented DB canals. Transportation values were not significantly different between file systems in MB canals, but significantly higher (42-65% average, p< 0.001) for Vortex Blue files in DB canals. Impressively, the mean transportation value of DB canals instrumented to 40/0.04 by ZenFlex was 66% that of DB canals instrumented to 35/0.04 by Vortex Blue (p=0.005). Location of the curve is an important factor in studying relative performance between different file systems with similar geometry in terms of size/taper. Use of 3D-printed replicas can help in acquiring statistically robust relevant data. S10OD021533.