The navy initially researched NiTi alloys in the 1950s-1960s as a non-magnetic, waterproof, and salt resistant material. Initial tests found NiTi to exhibit superelastic properties, making it useful for applications between 10-125°C including orthodontics, endodontics, and orthopedics/oral surgery. NiTi was first used in endodontic hand files in 1988 and shown to be more flexible and resistant to fractures than stainless steel. Rotary NiTi files were developed in the early 1990s and found to shape canals faster and with fewer errors than hand files.