title: Temperature rise on the surface of NiTi and stainless steel fractured instruments during ultrasonic removal.
abstract: OBJECTIVE
  To investigate the temperature rise induced by ultrasonic tips when activated against two types of fragments at two power-settings.
  
  
  METHODS
  Twenty-four F2-ProTaper Universal rotary files and 36 stainless steel K-files, size 50, were sectioned at a point 5.5 mm from their tips. At specific power-settings, ET40D ultrasonic tips were activated against the peripheral surface of the fragment coronal part (1 mm) for 30 s with/without Air-Active function according to each group; (i) without Air-Active function at power-setting 1.5 against NiTi fragments, (ii) without Air-Active function at power-setting 1.5 against SS fragments, (iii) without Air-Active function at power-setting 3 against SS fragments, (iv) with Air-Active function at power-setting 3 against SS fragments, and (v) with Air-Active at power-setting 3 against NiTi fragments. Temperature rises were inspected at 15 and 30 s using the thermocouples.
  
  
  RESULTS
  With no Air-Active function and power-setting 1.5, the temperature rises induced on NiTi fragments at 15 and 30 s (36.33 and 55.44 °C, respectively) were significantly greater than those induced on SS fragments at 15 and 30 s (26.08 and 35.27 °C, respectively) (P = 0.001 and <0.001, respectively). When ultrasonic tips were activated against SS fragments without Air-Active, the temperature rises induced by power-setting 3 at 15 and 30 s (35.25 and 45.32 °C, respectively) were significantly greater than those induced by power-setting 1.5 at the same intervals (26.08 and 35.27 °C, respectively) (P = 0.006 and 0.012, respectively). At 30 s, the overall temperature rise induced with Air-Active (25.56 °C) was significantly lower than that induced without Air-Active (45.34 °C) (P < 0.001).
  
  
  CONCLUSIONS
  Lower power-settings and shorter application times are recommended when using ultrasonics for removal of NiTi fragments compared with SS ones. Air-Active function, as a coolant, is recommended when dealing with both types of fragments.
authors.affiliation: Department of Restorative Dental Sciences, College of Dentistry, Taibah University, Al-Madina Al-Munawarah, Saudi Arabia.
authors.forename: A A
authors.initials: AA
authors.lastname: Madarati
mesh_terms: D003762:Dental Instruments; D004868:Equipment Failure; D005547:Foreign Bodies / Q000628:therapy; D006358:Hot Temperature; D009532:Nickel; D013193:Stainless Steel; D014025:Titanium; D014464:Ultrasonic Therapy / Q000009:adverse effects / Q000295:instrumentation*
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium
keywords: complications; fractured; removal; separated; temperature; ultrasonics