ProFile Vortex Instruments after Clinical Use:
A Metallurgical Properties Study
Ya Shen, DDS, PhD,* Jeffrey M. Coil, DMD, MSD, PhD,* Hui-min Zhou, DDS, PhD,†
Esther Tam, DDS,* Yu-feng Zheng, PhD,‡ and Markus Haapasalo, DDS, PhD*
Abstract
Introduction:
The aim of the study was to analyze the
incidence and mode of ProFile Vortex instrument (Dentsply Tulsa Dental Specialties, Tulsa, OK) defects during
a predefined schedule of clinical use by the undergraduate students in a dental school setting and to examine
the metallurgical characteristics of unused and clinically
used Vortex instruments.
Methods:
A total of 2,203
ProFile Vortex instruments discarded after single use
from the undergraduate students program over 24
months were collected and examined for defects using
a stereomicrosocpe at 10 magnification. The incidence
and type of instrument defects or separation were
analyzed. The lateral surfaces of part of the defected
instruments and fracture surfaces of fractured files
were examined using scanning electron microscopy.
Unused and clinically used files were examined by differential scanning calorimetry and X-ray diffraction. Vickers
hardness of the files was measured with a 200-g load.
Results:
Only 1 of the 2,203 files fractured during clinical use. The cause of fracture was shear stress, and the
file also showed unwinding of the helix structure. None
of the remaining 2,202 files exhibited unwinding after
clinical use. Blunt apicals were detected in 86 used files
(3.9%). Austenite-finish temperatures were very similar
for asreceived, used files with defects and used files
without defects, all exceeding 50 oC. No difference in mi-
crohardness was detected among these 3 instrument
groups. X-ray diffraction results showed that NiTi files
had austenite structure at room temperature.
Conclusions:
The risk of ProFile Vortex fracture is very low
when files are used 1 time by undergraduate students.
Unwinding of the files was not detected except for the
fractured file. Clinical single use had no detectable effect
on austenite-martensite phase transformation of the
files. Unused and clinical single-use files contain a similar
phase structure at body temperature.
Key Words
Defect, differential scanning calorimetry, endodontic instrument, M-Wire, nickel-
titanium instrument, ProFile Vortex, x-ray diffraction
(J Endod
2012;38:1613–1617)
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