MACHINING EFFICIENCY AND WEAR-RESISTANCE OF NICKEL-TITANIUM ENDODONTIC FLIES

Objective. Nickel-titanium endodontic files are more flexible than sta inless steel. Little information is reported concerning machining effi ciency and wear resistance of nickel titanium. This study assessed the dentin-machining ability and wear resistance of nickel titanium endod ontic files in vitro. Study Design, The method described earlier to as sess machining efficiency and wear resistance of stainless steel files was used. Eight different types and brands of nickel titanium files w ere studied: Ultra-Flex Hedstrom, Ultra-Flex K, Mity Hedstrom, Mity K, Mity Turbo, Hedstrom Naviflex NT, NiTiflex, and Hyflex X-file. Thirty files of each brand were evaluated. One-way ANOVA and t tests were pe rformed to analyze the data. Results, Considerable variation was found in machining efficiency and wear. The best initial machining ability of all nickel titanium instruments was recorded for the Hyflex-X file (0.60 +/- 0.16 mm(2)); the poorest performance was for the Mity Turbo file, which machined less than one third of the best performing instru ment (0.19 +/- 0.12 mm(2)). Conclusions. We compared our results with results of a previous study of stainless steel endodontic files and co ncluded that nickel titanium instruments are as aggressive as or bette r than stainless steel instruments in removing dentin. They are also m ore durable than their stainless steel counterparts.