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rev port estomatol med dent cir maxilofac . 2021;62(1):1-8 3

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cians. Although PTG SX replica -like instruments are already tion was performed with a dental operating microscope (Opmi
available in the market, there is currently no scientific support Pico, Carl Zeiss Surgical, Germany) under a 3.4x and 13.6x mag-
regarding their characteristics and safety. nification to analyze the following characteristics: (a) number
Considering the lack of knowledge on PTG SX replica -like of blades in the active area (measured in units); (b) helix angle
instruments, a multimethod research was conducted to assess average in the active area (measured in degrees). A photo was
their design, metallurgic features, torsional strength, and flex- taken perpendicular to the long axis of the instruments using
ibility. The null hypothesis to be tested was that there was no a Canon EOS 500D camera (Canon, Tokyo, Japan) and trans-
difference between the SX replica -likes and the original Pro- ferred in the jpeg format to the ImageJ software (Laboratory
Taper instruments regarding design, torsional strength, and for Optical and Computational Instrumentation [LOCI], Wis-
flexibility. consin, USA). In ImageJ, the six most coronal helix angles were
measured three times and averaged, and (c) major defects or
deformations such as distorted, missing, or twisted blades,
Material and Methods were identified. High -magnification analysis was conducted
on a conventional scanning electron microscope (SEM) Hitachi
Ninety -three SX NiTi instruments of two replica -like (Premi- S -2400 (Hitachi, Tokyo, Japan) to qualitatively assess the fol-
um Taper Gold and Go -Taper Flex) rotary systems that repli- lowing: (a) blade spiral design (symmetrical or asymmetrical,
cate the premium brand ProTaper Gold (Table 1, Figure 1) were with or without radial lands); (b) instrument’s tip (active or
assessed regarding their design, nickel -titanium (NiTi) com- non -active tip); (c) cross -sectional geometry; (d) surface marks
position, phase transformation temperatures, and torsional associated with a possible machined production process; (e)
and bending strengths. The replica -like systems for the pres- minor defects or deformations.
ent study were selected according to a previously reported Two laboratory tests were performed for metallurgical
definition. 8 characterization: energy -dispersive X -ray spectroscopy (EDS/
Six random new instruments were selected in each group SEM) and differential scanning calorimetry (DSC). In EDS/
for design assessment. The stereomicroscopic visual inspec- SEM, three new SX instruments per group were analyzed us-
ing a conventional SEM (Hitachi S -2400; Hitachi, Tokyo, Ja-
pan) equipped with an energy -dispersive X -ray spectrometer
with light elements detector (Bruker Quantax, Bruker Corpo-
ration, Billerica, MA, USA). Before this analysis, all instru-
ments had their surface cleaned by immersion on an acetone
bath for 2 minutes and were mounted on a sample holder
placed in the microscope chamber. The vacuum was created
for approximately 10 minutes. As for the operative setting
conditions, the acceleration voltage was 20 kilovolts, and the
filament current was 3.1 amp at a 25 -mm work distance on
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a surface area of 400 µm . Results were assessed using the
Sigma Scan software (Systat Software Inc., San Jose, CA) and
the proportions of nickel and titanium were obtained by a
typical spectrum.
The DSC test was carried out in two different instruments
of each system following the American Society for Testing and
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Materials’ guidelines. It was performed on 3 to 5 -mm frag-
Figure 1. Macroscopic images of two replica -likes and ments with a weight of 15–20 mg removed from the active
the original brand SX instruments (from left to right: portion of the tested files. Each fragment was submitted to a
ProTaper Gold, Premium Taper Gold, and Go -Taper Flex)
with the corresponding labelled packing box. chemical etching bath composed of a mixture of 25% hydro-
fluoric acid, 45% nitric acid, and 30% distilled water for ap-

Table 1. Characteristics of ProTaper Gold SX and two replica -like rotary NiTi instruments.
Corresponding Manufacturer Identification Acquisition from Reference
System Brand Type Lot a
NiTi metal alloy Specifications (Color Coding) (Country) Price Value
ProTaper Premium Dentsply SX Local market
Gold SX Thermo -treated brand (Ballaigues, Switzerland) (no color ring) (Portugal) 1546778 1.00
Premium Thermo -treated Replica -like Waldent SX Local market 201808 0.29
Taper Gold SX (City not stated, China) (no color ring) (India)

Go -Taper Thermo -treated Replica -like Access SX Local market 17110103 0.46
Flex SX (Shenzhen, China) (no color ring) (Portugal)
a Reference price values of replica -like instruments were rated at the time they were acquired based on the reference price of the premium
brand instrument categorized as 1.