Resumen de Shaping ability of NiTi rotary versus stainless steel hand instruments in simulated curved canals
Objectives: The purpose of this in-vitro study was to compare shaping ability of NiTi rotary Mtwo and FlexMaster with stainless steel hand K-Flexofile in simulated curved root canals.
Study Design: Forty-five simulated canals in resin blocks were prepared with Mtwo, FlexMaster and stainless steel hand K-Flexofile (15 blocks in each group). Using pre- and post- instrumentation images, straightening of the canal curvature was determined with a computer image analysis program. Material removal was measured at 5 measuring points, beginning 1 mm from the apex. Changes of working length (WL) were also recorded. The data were analyzed statistically using paired T-test and one way ANOVA.
Results: The mean material removal from the inner canal wall was different from the outer canal wall at all measuring points for each system (p < 0.0001) except for FlexMaster at WL-9 (p = 0.123) and K-Flexofile at WL-5 (p = 0.093). The mean ratio of material removal (inner/outer) at all measuring points was different for all systems except for FlexMaster and Mtwo at 3, 5 mm (p = 0.984, p = 0.242), and K-Flexofile and rotary systems at 1, 3 mm from the apex (p = 0.565, p = 0.218) (p = 0.794, p = 0.693). A mean loss of working length of 0.02 mm for Mtwo and 0.01 mm for FlexMaster and K-Flexofile was measured although the difference was not significant.
Conclusions: In the apical points of the curvature (1, 3 mm), there was no significant difference between three systems. At point 5mm from the apex, K-Flexofile remained better centered, while in the coronal points (7, 9 mm) NiTi rotary systems achieved better canal geometry.
