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76 rev port estomatol med dent cir maxilofac. 2018;59(2):75-79

Resistência à fadiga cíclica do sistema ProTaper Gold
e comparação com o sistema ProTaper Universal

r e s u m o

Palavras-chave: Objetivos: O principal objetivo deste estudo foi caracterizar a resistência à fadiga cíclica do
Endodontia sistema ProTaper Gold e compará-la à resistência à fadiga do sistema ProTaper Universal.
Resistência à fadiga Métodos: Um sistema mecânico que simula um canal radicular com curvatura de 4,7 mm
Instrumentos níquel-titânio de raio e angulo de 45º foi usado para desempenhar os testes de resistência à fadiga cíclica.
ProTaper Gold Neste, limas ProTaper Gold e ProTaper Universal dos tamanhos F2 e F3 foram testadas a uma
ProTaper Universal velocidade rotacional de 300 rpm e torque de 4 N.cm, sendo divididas em 4 grupos experi-
mentais. O tempo até a fratura ocorrer foi registado e o número de ciclos até a fratura foi
calculado. A análise estatistica foi realizada utilizando os testes de Kolmogorov-Smirnov,
T-student e U Mann-Whitney (p<0,05).
Resultados: O grupo de limas ProTaper Gold F2 mostrou ter uma média de número de ciclos
até a fratura superior ao grupo de ProTaper Universal F2 (p<0,05). Em relação aos intrumen-
tos F3, a mesma tendência ocorreu: o número de ciclos até a fratura dos intrumentos Pro-
Taper Gold foi estatisticamente superior (p<0,05).
Conclusões: O sistema ProTaper Gold provou ter uma maior resistência à fadiga cíclica que o sis-
tema ProTaper Universal. Além disso, instrumentos de diâmetro maior mostraram ter um menor
número de ciclos até à fratura. (Rev Port Estomatol Med Dent Cir Maxilofac. 2018;59(2):75-79)
© 2018 Sociedade Portuguesa de Estomatologia e Medicina Dentária.
Publicado por SPEMD. Este é um artigo Open Access sob uma licença CC BY-NC-ND
(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Manufacturers proclaim that PTG system has improved
Introduction
fatigue resistance over PTU mainly due to this technology, so
Pulpal treatment may be challenging since a complex root ca- several amounts of independent research have been made
nal anatomy and limitations inherent to instruments used concerning this issue.
during root canal preparation are major concerns. Thus, the main aim of this in vitro study was to analyze
1
Over time several types of endodontic instruments have the fatigue life of the ProTaper Gold RM NiTi instruments and
been developed overcoming their predecessors with new to compare the fatigue life of PTG system with its predecessor,
technology. Niquel titanium (NiTi) instruments, for example, confirming recent findings.
had proven to be more resistant to fatigue than stainless steel
ones. Even though, instrument breakage may occur often. 2-6
Fracture occurs when an instrument shanks loosely in a canal Materials and methods
generating tension/compression cycles until fracture arise at
the maximum flexural point. 3,6,7 Apparently, this is one of the Forty-eight sterile and new rotary files from PTG and PTU sys-
major reasons for instrument breakage during treatment and tems were experimentally tested at room temperature (≈ 20º)
4,8
can be measured by the number of cycles to fracture (NCF). constituting 4 experimental groups (PTG F2= 12), (PTG F3= 12),
NCF may be affected by type of wire, surface finish, thermal (PTU F2= 12), (PTU F3= 12).
treatments, cross section and geometry of the instrument. 5,9-13 Those instruments were subjected to a cyclic fatigue test
®
ProTaper Universal (PTU; Dentsply/Maillefer, Ballaigues, using a static model for cyclic fatigue testing as seen in Figure 1.
CH) is a widely-described system of instruments, with progres- The instrument was able to rotate freely inside a 45º angle and
sive taper over the cutting blades, triangular cross section and 4.7 mm radius of curvature artificial canal.
center of rotation equal to center of mass. The basic sequence A single operator performed the entire protocol which in-
of instrumentation comprehends the use of 6 instruments: 3 cluded first to place the instrument to be tested in the con-
to pre-enlarge the coronal and medial third (SX, S1 e S2) and tra-angle and rotate the head of the contra-angle until the
other 3 to shape the apical third (F1, F2 e F3). 14 instrument was parallel to the part that simulated the apical
Recently introduced in the market ProTaper Gold RM instru- canal. Ensure that the instrument was perpendicular to the
ments (PTG; Dentsply Tulsa Dental Specialities, OK, USA), re- upper part of the block, well-adjusted between the two pieces
spect the same geometry principles of PTU, with the same that impose radius of curvature and angle, and the extremity
number of instruments and directions for use. However, a pat- of the file being well positioned at the established point. After
ented heat treatment called controlled memory wire (CM- that, the position of the parts was fixed by tightening the bolts.
®
Wire ) is used in this instruments’ manufacture. 13,15 The WaveOne TM motor equipment was in the ProTaper Uni-