TY - JOUR
T1 - Chemical Analysis of Nickel-Titanium Rotary Instruments with and without Electropolishing after Cleaning Procedures with Sodium Hypochlorite
AU - Bonaccorso, Antonio
AU - Schäfer, Edgar
AU - Condorelli, Guglielmo Guido
AU - Cantatore, Giuseppe
AU - Tripi, Teresa Roberta
PY - 2008/11
Y1 - 2008/11
N2 - The aim of this study was to chemically analyze rotary nickel-titanium instruments with and without electropolishing after cleaning procedures with NaOCl. To evaluate the effect of 5.25% NaOCl on electropolished RaCe instruments, a total of 18 instruments were tested. A control group of 18 nonelectropolished RaCe instruments was used. The surface of each instrument was analyzed before and after cleaning in NaOCl by using energy dispersive x-ray analysis, Auger electron spectroscopy, and scanning electron microscopy. Surface defects were recorded, and a χ2 test was used for statistical analysis. After immersion in NaOCl, the nonelectropolished and electropolished files showed a significant increase of iron deposits as a result of galvanic corrosion of the shaft (P <.05). The nonelectropolished files showed marked presence of NaCl deposits in the machining marks and microcracks. As regards the chemical nature of the surface, the electropolished files had an oxide increase compared with the low oxide concentration (mainly TiO2) before cleaning. The nonelectropolished files already possessed higher oxides concentration (TiO2 and NiO) before NaOCl cleaning. NaOCl treatment affects the chemical composition of the surface and, in particular for nonelectropolished instruments, of the bulk exposed through machining marks and fabrication microcracks.
AB - The aim of this study was to chemically analyze rotary nickel-titanium instruments with and without electropolishing after cleaning procedures with NaOCl. To evaluate the effect of 5.25% NaOCl on electropolished RaCe instruments, a total of 18 instruments were tested. A control group of 18 nonelectropolished RaCe instruments was used. The surface of each instrument was analyzed before and after cleaning in NaOCl by using energy dispersive x-ray analysis, Auger electron spectroscopy, and scanning electron microscopy. Surface defects were recorded, and a χ2 test was used for statistical analysis. After immersion in NaOCl, the nonelectropolished and electropolished files showed a significant increase of iron deposits as a result of galvanic corrosion of the shaft (P <.05). The nonelectropolished files showed marked presence of NaCl deposits in the machining marks and microcracks. As regards the chemical nature of the surface, the electropolished files had an oxide increase compared with the low oxide concentration (mainly TiO2) before cleaning. The nonelectropolished files already possessed higher oxides concentration (TiO2 and NiO) before NaOCl cleaning. NaOCl treatment affects the chemical composition of the surface and, in particular for nonelectropolished instruments, of the bulk exposed through machining marks and fabrication microcracks.
KW - Corrosion
KW - micro-cracks
KW - RaCe
KW - sodium hypochlorite
KW - surface defects
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U2 - 10.1016/j.joen.2008.08.004
DO - 10.1016/j.joen.2008.08.004
M3 - Article
C2 - 18928855
AN - SCOPUS:53549124103
VL - 34
SP - 1391
EP - 1395
JO - Journal of Endodontics
JF - Journal of Endodontics
SN - 0099-2399
IS - 11
ER -