Endodontic rotary nickel-titanium instrument systems.PDF

Since the end of the nineteenth century, automated root canal instrumentation has been available, but systems had many problems. The challenges of increased canal blockage, instrument breakage, and insufficient canal debridement were related to the use of stainless steel instruments and have been dramatically improved with the introduction of nickel-titanium (NiTi) files. The first useable NiTi alloy was developed by William Buehler in 1960 at the U. S. Navy Ordinance Lab in Silver Spring, Maryland. Walia et al. investigated the feasibility of using this alloy in the fabrication of endodontic files, and showed that NiTi files had two to three times the elastic flexibility in bending and torsion, as well as superior resistance to torsional fracture when compared with stainless steel files of the same size. These features led to better centering of the instruments within the canal (1), less straightening of the canal, fewer elbows and ledges, and less transportation (2).