Oberflächenuntersuchung von Edelstahlfeilen nach chemisch-physikalischer Belastung

Problem: Stainless steel hedstromfiles have been used in endodontics for decades as reliable instruments for cleaning and shaping the root canal. Worldwide they are mostly used in combination with Sodiumhypochloride irrigant solution, but the relatively high electrochemical aggressiveness of this solution could cause corrosion on stainless steel files. Aim: The purpose of this study was to examine if stainless steel hedströmfiles from the companies Maillefer, FKG, Kerr and VDW all show the same corrosion stability. Methodology: Cyclic voltammmetry has been done one 72 files and 24 files have been surveyed by the Turnbulls-Blue test. In addition 12 files were pretested in a in a SEM experiment. In the main study 40 files went through one, 40 files through five and 40 files through no chemo-mechanical treatment cycles. Within one treatment cycle the file was mechanically stressed while being in contact with human tooth material and NaOCl solution. Then the file was desinfected, ultrasonically cleaned and sterilized. Afterwards all files were examined under the scanning electron microscope (SEM). Some representative files were additionally surveyed by energy dispersive spectrometry (EDS). Results: The cyclic voltammetry showed significantly (p ≤ 0,05) or even very significantly (p ≤ 0,01) worse results for the Maillefer files in comparison to the other files. Best results in this experiment were measured for the VDW files. In contrast to the cyclic voltammetry the Turrnbulls blue test showed the VDW files to be the least corrosion resistant. None of the files in the main study showed corrosion signs. Conclusions: The corrosion susceptability of stainless steel files seems to be very low under practical conditions.