Efficacy of Controlled Memory and Shape Memory Nickel Titanium Instruments in Removing Filling Material from Severely Curved Root Canals: An Study.

Introduction: The aim of the present study was to compare the efficacy of four NiTi instruments with different properties (shape memory and control memory), in both rotary and reciprocating motions, during retreatment procedures.

Methods And Materials: Mesial canals of thirty-two mandibular molars were instrumented, obturated, and then scanned with" Cone-beam Computed Tomography" (CBCT). Teeth were randomly divided into 4 groups (=8) according to each system: "Shape Memory" (SM) instruments including Reciproc (R25 file) and ProTaper Next (X3 and X2 file), "Controlled Memory" (CM) instruments including WaveOne Gold (Primary file) and Hyflex (30.