title: A novel methodology to evaluate the use of an ultrasonic tip.
abstract: BACKGROUND
  The purpose of this in vitro investigation was to use a novel methodology to evaluate the use of an endodontic ultrasonic (US) tip.
  
  
  METHODS
  BUC 1 US tips (n = 10) were mounted to a testing apparatus that applied a linear movement of the US tip to dentin specimens with an axial force of 15 g. Instrumentation was activated for 20-second cycles up to a 2-minute baseline and continued for 10-minute intervals up to a defined inefficient/dropout point. Dentin cutting efficiency was measured by the change in weight of dentin specimens to the nearest 0.01 mg. A quantitative analysis was conducted on length and diameter of the US tips by using images taken at 15.625 magnification and 1000 pixels/cm (1 pixel = 0.01 mm) resolution. Weight of dentin specimens and images were captured at 2, 50, 100, 150, and 190 minutes of instrumentation.
  
  
  RESULTS
  There was no statistically significant difference in dentin removal between measurement times for any US tip specimen. There was a statistically significant difference in tip length over time (P = .002). Tukey post hoc analysis revealed that tip length decreased significantly at 2 minutes of instrumentation.
  
  
  CONCLUSIONS
  Within the limits of this investigation, the BUC 1 US tip did not significantly decrease in efficiency between 2 and 190 minutes of use. The decrease in tip length was found to be significant at 2 minutes of instrumentation. Adding a linear movement, in addition to an axial force, for testing US tips will make future investigations more clinically relevant.
authors.affiliation: Department of Endodontics, University of Missouri-Kansas City, School of Dentistry, Kansas City, Missouri, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Cloutier
authors.forename: James C
authors.initials: JC
authors.lastname: Kulild
authors.forename: Mary P
authors.initials: MP
authors.lastname: Walker
mesh_terms: D003762:Dental Instruments; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods; D003804:Dentin; D006801:Humans; D019563:Mechanics; D018915:Root Canal Preparation / Q000295:instrumentation*; D016369:Smear Layer; D014464:Ultrasonic Therapy / Q000295:instrumentation*