AIM To determine how instrument design affects the fatigue life of two nickel-titanium (Ni-Ti) rotary systems (Mtwo and ProTaper) under cyclic fatigue stress in simulated root canals. METHODOLOGY Cyclic fatigue testing of instruments was performed in stainless steel artificial canals with radii of curvature of 2 or 5 mm and an angle of curvature of 60 degrees . A total of 260 instruments were...

AIM To investigate the morphological changes in the apical third of the root canal after preparation with three techniques. METHODOLOGY Forty molar teeth were scanned using micro-computed tomography before and after instrumentation with: Group 1 - stainless steel K-files using the balanced force technique; Group 2 - stainless steel K-files (balanced force) and then refining the apical prepara...

INTRODUCTION The aim of this study was to evaluate, using cone-beam computed tomography (CBCT), transportation and centralization of different nickel-titanium (NiTi) rotary instruments. METHODS One hundred and twenty eight mandibular premolars were selected and instrumented using the following brands of NiTi files: WaveOne, WaveOne Gold, Reciproc, ProTaper Next, ProTaper Gold, Mtwo, BioRaCe a...

This study investigated the incidence of hand and rotary instrument separation (IS) in the endodontics graduate program at the University of Pennsylvania between 2000 and 2004. In 4,865 endodontic resident cases the incidence of hand and rotary IS was 0.25% and 1.68%, respectively. The odds for rotary IS were seven times more than for hand IS. The probability of separating a file in apical thir...

AIM The aim of the study is to compare the maximum stress distribution on the rotary retreatment instruments within the root canal at cervical, middle, and the apical one-third during retreatment of gutta-percha. MATERIALS AND METHODS A human mandibular premolar was scanned, and three-dimensional geometry of the root was reconstructed using finite element analysis (FEA) software package (ANSY...

AIM To evaluate the bending fatigue lifetime of nickel-titanium alloy (NiTi) and stainless steel (SS) endodontic files using finite element analysis. METHODOLOGY The strain-life approach was adopted and two theoretical geometry profiles, the triangular (TR) and the square cross-sections, were considered. Both low-cycle fatigue (LCF) lifetime and high-cycle fatigue (HCF) lifetime were evaluate...