Topographic and Chemical Analysis of Reciprocating and Rotary Instruments Surface after Continuous Use.

Mariana Mena Barreto Bastos,Emílio Carlos Sponchiado Júnior,Lucas Da Fonseca Roberti Garcia,Ana Mena Barreto Bastos,André Augusto Franco Marques,Aida Rene Assayag Hanan

doi:10.1590/0103-6440201701528

Mariana Mena Barreto Bastos, Emílio Carlos Sponchiado Júnior + Show 4 more

Open Access

https://doi.org/10.1590/0103-6440201701528

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Abstract

This study aimed at evaluating the changes in surface characteristics and NiTi content of reciprocating and rotary instruments after continuous use. Thirty brand-new instruments were assigned to 3 groups (n=10): PNX1 Group - ProTaper Next system - instrument X1; PNX2 Group - ProTaper Next system - instrument X2 and WO Group - WaveOne system - Primary instrument 25.08. The instruments were used to prepare 60 simulated root canals. Analysis of surface characteristics by scanning electron microscopy (SEM) and chemical analysis of Ni and Ti content by energy-dispersive spectroscopy (EDS) were performed before and after the first and third use of the instruments. Only WO Group had significant increase in the quantity of defects and deformations after the third use (p<0.05). PNX1 Group had significant decrease in Ni content after the third use, in comparison with the unused instruments (p<0.05). PNX1 Group had no decrease in Ti content throughout the time of use (p>0.05), however, in PNX2 Group, there was significant decrease in the different time interval of analysis (p<0.05). Continuous use promoted increase in defects and deformations only for WaveOne instruments. Chemical composition presented significant changes according to the time of instruments use.

Highlights

The development of new instruments, such as those made from nickel-titanium (NiTi) alloy, has been essential for the enhancement of root canal preparation techniques, making them faster and more efficient to perform [1]
The instruments were removed from their packaging materials, and randomly distributed into 3 groups (n=10), using the Random Sequence Generator program, as follows: PNX1 Group - ProTaper system
Discussion preparation of a maximum of 3 or 4 canals, according to their manufacturers. As they are manufactured of M-Wire alloy, the clinical reuse of these instruments must be

Summary

Introduction

The development of new instruments, such as those made from nickel-titanium (NiTi) alloy, has been essential for the enhancement of root canal preparation techniques, making them faster and more efficient to perform [1]. Among the characteristics of these instruments, flexibility, cyclic fatigue and torsional resistance are the most important, as they allow safer biomechanical preparation of canals with accentuated curvature [2,3]. Among the new manufacturing strategies, thermomechanical treatment of conventional NiTi alloy led to the M-Wire alloys [5]. Instruments manufactured using this new technology have superelasticity, and greater flexibility and cyclic fatigue resistance than conventional. The superelasticity is associated to transformation of the alloy martensitic phase into austenitic when submitted to stress, followed by spontaneous reversion to martensitic phase after stress release, making the instrument recover its original shape [4,5]

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