Objectives To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. Materials and Methods The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicula...

NiTi instruments have a high risk of separation due to torsional or flexural fatigue (cyclic fatigue). Chemomechanical preparation, cleaning procedures, chemical disinfection and sterilization cause the corrosion of endodontic instruments that may weaken the fracture resistance of the instruments. Objective To assess the effects of NaOCl immersion and autoclave sterilization on the cyclic fatig...

INTRODUCTION Cyclic fatigue is the common reason for breakage of rotary instruments. This study was conducted to evaluate the effect of cryogenic treatment (CT) in improving the resistance to cyclic fatigue of endodontic rotary instruments. METHODS AND MATERIALS In this in vitro study, 20 RaCe and 20 Mtwo files were randomly divided into two groups of negative control and CT. CT files were st...

Objectives This study evaluated the amount of remaining root canal filling materials after retreatment procedures performed by undergraduate students using manual, rotary, and reciprocating techniques through micro-computed tomographic analysis. The incidence of instrument fracture and the instrumentation time were also evaluated. Materials and Methods Thirty maxillary single rooted teeth wer...

INTRODUCTION This study compared the cleaning efficiency of Mtwo, Race and Medin Nickel-Titanium (NiTi) rotary instruments. MATERIALS AND METHODS Sixty mandibular molar mesial roots were selected with angle curvatures between 25-35 degrees and divided into three groups; each containing 20 teeth. Canals were prepared with the rotary files and irrigated with 2.5% NaOCl solution after each instr...

INTRODUCTION Disinfection and subsequent obturation of the root canal space require adequate mechanical enlargement of the canals. The purpose of this in vitro study was to compare the shaping ability of Mtwo, RaCe and Medin rotary instruments during the preparation of curved root canals. MATERIALS AND METHODS Sixty mesiobuccal root canals of mandibular molars with severe curvatures between 2...

INTRODUCTION The aim of the present study was to determine the disinfection of preparations carried out by using the Protaper or MTwo system in canals infected with Enterococcus faecalis. METHODS Twenty-eight distobuccal canals of upper molars were used, in which the canals were sterilized after being enlarged to #20 file and then contaminated with an inoculation of a culture of E. faecalis. ...

Objective To evaluate transportation (T) and centering ability (CA) of root canal preparations using continuous or reciprocating nickel-titanium endodontic files. Materials and Methods Ninety-six mesiobuccal root canals of mandibular first and second molars were randomly divided into 6 groups (n=16) according to the rotary file used: 1. ProTaper Next; 2. ProTaper Gold; 3. Mtwo; 4. BioRaCe; 5....

BACKGROUND The aim of the present study was to evaluate the cyclic fatigue resistance of Mtwo NiTi rotary instruments after clinical use by 1 experienced and 1 novice operator. MATERIAL/METHODS Cyclic fatigue testing of instruments was performed on tapered artificial canals with a 5 mm radius of curvature and 60° angle of curvature. Twenty Mtwo instruments for each size were selected and divid...

OBJECTIVE To determine variation in post-instrumentation working length and root area in the following rotary systems: ProTaper, RaCe, Mtwo and K3. STUDY DESIGN A sample of 40 resin blocks with double curvature (at 14 and 16 mm) and a 33 degrees angle was used. Working length was verified with a digital measure using a number 10 K file. The specific sequence for each rotary system was followe...