A comparative photoelastic stress analysis of internal root stresses between RC Prep and saline when applied to the Profile/GT rotary instrumentation system

The purpose of this study was to measure and compare the amount of stress produced by GT ProFile (GT) and ProFile (PF) rotary files lubricated with either RC Prep (RCP) or saline (S) on the walls of prepared simulated canals. Twenty-four 10-mm long canals with a 10 mm radius of curvature were prepared in PL-2 photoelastic acrylic blocks which were lubricated with either RCP or S. The files were inserted into a Nouvag handpiece mounted to an Instron 4502 universal testing machine and lowered into the canal at a rate of 60 mm/min and a rotational speed of 300 RPM. The following four GTs and four PFs were sequentially introduced into predetermined depths of each canal: 20/.10, 20/.08, 20/.06, 20/.04, 40/.04, 35/.04, 30/.04, and 25/.04. Total areas of stress created by each file were captured by digital video images and measured using Image J software. Statistical analysis of the data was performed using a two-way ANOVA (p < 0.05, n = 24). The GT/RCP group demonstrated a significant average of 64.22% less stress than GT/S group. The PF (25, 30, and 35)/ RCP groups demonstrated a significant average of 27.02% less stress than the same S groups. PF (40) produced a negligible amount of stress regardless of the lubricant type. The results reveal that using RCP as a lubricant when instrumenting curved canals with GT and PF results in less stress when compared to saline.