The corrosive effect of root canal irrigants on endodontic instruments
Lin, C.P.; Lan, W.H.
Journal of the Formosan Medical Association 86(2): 144-151
1987
ISSN/ISBN: 0371-7682 PMID: 3106562 Document Number: 299603
The effect of currently available root canal irrigating solutions (5%, 2.5%, 1%, 0.5% NaOCl, 0.9% NaCl, 3% H2O2, 15% EDTA, and the blended solutions (1:1 v/v) of 5% NaOCl-15%EDTA, 5%NaOCl-3%H2O2, 5%NaOCl-0.9%NaCl) on the corrosion behavior of the endodontic carbon steel GGD and stainless steel K-file was studied by means of electrochemical techniques. Scanning electron microscopy was also used to characterize the corrosion patterns of instruments and to corroborate the results of electrochemical analysis. From the results of this investigation, the following conclusions can be drawn: (1) Lower NaOCl concentration decreases the corrosivity of the solution. (2) EDTA and H2O2 appear less corrosive as compared with NaOCl and NaCl solutions. (3) The combination of NaOCl (5%) with either H2O2 or EDTA becomes more destructive to the instruments than the single component solutions. (4) For carbon steel instruments, corrosion is readily detected after a duration of immersion as short as 10 minutes. Whereas for stainless steel, although more noble than carbon steel, pitting corrosion may develop within 1 week of immersion. Furthermore, the conclusions of this study suggest that the best final irrigating medium in the root canal is 3% H2O2 or 15% EDTA solution during instrumentation. Thereafter, the instrument has to be cleansed immediately in order to avoid destruction of its integrity.