AIM The purpose of this study was to establish a general mathematical model for describing the mechanical behaviour of root canal instruments by combining a theoretical analytical approach with a numerical finite-element method. METHOD Mathematical formulas representing the longitudinal (taper, helical angle and pitch) and cross-sectional configurations and area, the bending and torsional ine...

Cyclic fatigue of nickel-titanium, engine-driven instruments was studied by determining the effect of canal curvature and operating speed on the breakage of Lightspeed instruments. A new method of canal curvature evaluation that addressed both angle and abruptness of curvature was introduced. Canal curvature was simulated by constructing six curved stainless-steel guide tubes with angles of cur...

background: root canal cleaning is an important step in endodontic therapy. in order to develop better techniques, a new generation of endodontic instruments has been designed. the aim of this study was to compare the effectiveness of manual k-files (mani co, tokyo, japan) and two rotary systems–mtwo (dentsply-maillefer, ballaigues, switzerland) and protaper (vdw, munich, germany)–for root cana...

Nickel-titanium (Ni-Ti) instruments are widely used in adult endodontics as an efficient technique, but are rarely used for endodontic treatment for primary molars. To explore the feasibility of using Ni-Ti rotary instruments for root canal preparation in primary molars, 51 primary molars with intact root apex in 22 children, who ranged in age from 3.2 years to 7.7 years, were treated. A modifi...

The nickel-titanium alloy Nitinol has been used in the manufacture of endodontic instruments in recent years. Nitinol alloys have greater strength and a lower modulus of elasticity compared with stainless steel alloys. The super-elastic behaviour of Nitinol wires means that on unloading they return to their original shape following deformation. These properties are of interest in endodontology ...

This study investigated the retreatment effectiveness of .04 Taper nickel-titanium rotary ProFiles. Thirty extracted single-rooted anterior teeth were instrumented and obturated with gutta-percha/Roth's Sealer using lateral condensation. They were distributed into three groups of 10 each. Retreatment for group A was done using Profile alone, group B using Profile and chloroform, and group C usi...

BACKGROUND The cleaning of endodontic and all dental instruments prior to sterilization is a prerequisite for their processing for re-use. This study aimed to develop a clinically practical cleaning protocol for rotary nickel-titanium (NiTi) endodontic files prior to sterilization. METHODS Cleaning experiments were conducted on six different types of files that had been used on human teeth. T...

The introduction of nickel-titanium (NiTi) as material for endodontic instruments about 15 years ago opened many new perspectives. Many dentists and scientists see a benefit in using NiFi files. Initial problems such as frequent fractures and the uncertainty of the best way to use them have been solved. Other challenges such as enhancing the cutting ability or optimizing the speed, torque, and ...

Since the introduction of engine-driven nickel-titanium (NiTi) instruments, attempts have been made to minimize or eliminate their inherent defects, increase their surface hardness/flexibility and also improve their resistance to cyclic fatigue and cutting efficiency. The various strategies of enhancing instrument surface include ion implantation, thermal nitridation, cryogenic treatment and el...