Fracture resistance of dental nickel–titanium rotary instruments with novel surface treatment: Thin film metallic glass coating
Journal
Journal of the Formosan Medical Association
Journal Volume
116
Journal Issue
5
Pages
373-379
Date Issued
2017
Author(s)
Abstract
Background/Purpose Dental nickel–titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. Methods A 200- or 500-nm thick Ti–zirconium–boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius?=?5?mm, angulation?=?60°) under a rotating speed of 300?rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. Results The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. Conclusion The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure. ? 2016
SDGs
Other Subjects
boron; dental alloy; glass; nitinol; titanium; zirconium; alloy; boron; dental alloy; glass; nitinol; titanium; trace element; zirconium; Article; controlled study; disease resistance; electron diffraction; endodontic file; endodontic procedure; material coating; scanning electron microscopy; stress fracture; structure analysis; surface property; thickness; tooth fracture; tooth root canal; transmission electron microscopy; X ray diffraction; adverse device effect; dental device; device failure; devices; evaluation study; human; materials testing; procedures; root canal preparation; surface property; tooth fracture; Alloys; Boron; Dental Alloys; Dental Instruments; Equipment Failure; Glass; Humans; Materials Testing; Root Canal Preparation; Surface Properties; Titanium; Tooth Fractures; Trace Elements; Zirconium
Publisher
Elsevier B.V.
Type
journal article