CUTTING EFFICIENCY OF NICKEL-TITANIUM ENDODONTIC INSTRUMENTS AND THE EFFECT OF SODIUM-HYPOCHLORITE TREATMENT

The purpose of this study was to assess the cutting efficiency of nick el-titanium (NiTi) files in the presence and absence of sodium hypochl orite (NaOCl) treatment, and compare them to a conventional stainless- steel K-type file, NiTi files from four manufacturers were randomly se lected and exposed to NaOCl for 12 or 48 h, or not at all, Their cutti ng efficiencies were then assessed, using a new methodology: ''mass of Plexiglass cut per energy used over 50 linear cutting motions.'' In t he absence of NaOCl, Brasseler (318 mu g/J) and Maillefer (280 mu g/J) NiTi files were most efficient, followed by JS Dental (71.4 mu g/J) a nd McSpadden (40 mu g/J). These differences were significant (p < 0.00 01), except for those between the latter two brands. Moreover, NaOCl t reatment did not alter the cutting efficiency of any brand of instrume nts significantly, When compared with conventional stainless steel fil es, all NiTi files tested were less efficient.