Abstract
Improvements in the thermomechanical processing procedures of NiTi wires have led to the development of new NiTi instruments that compose mainly of martensite crystals, making the wire stable at clinical condition. This study aimed at comparing the shaping ability of two rotary nickel-titanium systems manufactured from different NiTi wires. Twenty simulated root canals each with a curvature of 35° in resin blocks were divided into two groups of 10 canals each. Canals in the first group were prepared with superelastic F360 instruments (Gebr. Brasseler, Germany) while canals in the second group were prepared using controlled memory HyFlex®CM™ instruments (Coltène Whaledent, Switzerland). Images were taken before canal preparation and after the use of each instrument. The assessment of the canal shapes was accomplished with a computer image analysis program. Data were statistically analyzed using SPSS program. Within the limitation of this in vitro study, HyFlex®CM™ instruments remained better centered in the apical third of the canals. In most canal segments, no significant differences were observed between either system in the amount of material removed. Both systems were comparable to each other in regards to their ability to enlarge root canal in the same way without procedural errors.
Highlights
During the last decade, many dental companies have been directed for manufacturing of different NiTi rotary instruments with different designs including noncutting tips, radial lands, different cross sections, different helical angle, and varying tapers with the aim to improve their performance and to simplify the preparation procedure [1]
® TM HyFlex controlled memory (CM) NiTi files (Coltene Whaledent, Switzerland) are made from an innovative thermomechanical process of NiTi alloy with the property of “Controlled Memory” rather than “Superelastic property” of other conventional NiTi files [4]. ese instruments are in the martensite condition at body temperature [5]
E null hypothesis was that there would be no difference between superelastic, conventional NiTi instruments (F360)
Summary
Many dental companies have been directed for manufacturing of different NiTi rotary instruments with different designs including noncutting tips, radial lands, different cross sections, different helical angle, and varying tapers with the aim to improve their performance and to simplify the preparation procedure [1]. Thermal treatment of NiTi alloy is frequently used [2, 3] to further increase flexibility and fatigue resistance of rotary NiTi instruments rather than changes in instrument geometry [4]. Ey have a modified double S-shaped cross section and are made of conventional, superelastic NiTi alloy [7]. E null hypothesis was that there would be no difference between superelastic, conventional NiTi instruments (F360).
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